Historical trend in river ice thickness and coherence in hydroclimatological trends in Maine

USGS Publications Warehouse

Huntington, T.G.; Hodgkins, G.A.; Dudley, R.W.

2003-01-01

We analyzed long-term records of ice thickness on the Piscataquis River in central Maine and air temperature in Maine to determine whether there were temporal trends that were associated with climate warming. The trend in ice thickness was compared and correlated with regional time series of winter air temperature, heating degree days (HDD), date of river ice-out, seasonal center-of-volume date (SCVD) (date on which half of the stream runoff volume during the period 1 Jan. to 31 May has occurred), water temperature, and lake ice-out date. All of these variables except lake ice-out date showed significant temporal trends during the 20th century. Average ice thickness around 28 February decreased by about 23 cm from 1912 to 2001. Over the period 1900 to 1999, winter air temperature increased by 1.7??C and HDD decreased by about 7.5%. Final ice-out date on the Piscataquis River occurred earlier (advanced), by 0.21 days yr-1 over the period 1931 to 2002, and the SCVD advanced by 0.11 days yr-1 over the period 1903 to 2001. Ice thickness was significantly correlated (P-value < 0.01) with winter air temperature, HDD, river ice-out, and SCVD. These systematic temporal trends in multiple hydrologic indicator variables indicate a coherent response to climate forcing.

Nelson River and Hudson Bay

NASA Technical Reports Server (NTRS)

2002-01-01

Rivers that empty into large bodies of water can have a significant impact on the thawing of nearshore winter ice. This true-color Moderate Resolution Imaging Spectroradiometer (MODIS) image from May 18, 2001, shows the Nelson River emptying spring runoff from the Manitoba province to the south into the southwestern corner of Canada's Hudson Bay. The warmer waters from more southern latitudes hasten melting of ice near the shore, though some still remained, perhaps because in shallow coastal waters, the ice could have been anchored to the bottom. High volumes of sediment in the runoff turned the inflow brown, and the rim of the retreating ice has taken on a dirty appearance even far to the east of the river's entrance into the Bay. The sediment would have further hastened the melting of the ice because its darker color would have absorbed more solar radiation than cleaner, whiter ice. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

Evaporation of ice in planetary atmospheres - Ice-covered rivers on Mars

NASA Technical Reports Server (NTRS)

Wallace, D.; Sagan, C.

1979-01-01

The existence of ice covered rivers on Mars is considered. It is noted that the evaporation rate of water ice on the surface of a planet with an atmosphere involves an equilibrium between solar heating and radiative and evaporative cooling of the ice layer. It is determined that even with a mean Martian insolation rate above the ice of approximately 10 to the -8th g per sq cm/sec, a flowing channel of liquid water will be covered by ice which evaporates sufficiently slowly that the water below can flow for hundreds of kilometers even with modest discharges. Evaporation rates are calculated for a range of frictional velocities, atmospheric pressures, and insolations and it is suggested that some subset of observed Martian channels may have formed as ice-choked rivers. Finally, the exobiological implications of ice covered channels or lakes on Mars are discussed.

Antarctic ice shelf potentially stabilized by export of meltwater in surface river

NASA Astrophysics Data System (ADS)

Bell, Robin E.; Chu, Winnie; Kingslake, Jonathan; Das, Indrani; Tedesco, Marco; Tinto, Kirsty J.; Zappa, Christopher J.; Frezzotti, Massimo; Boghosian, Alexandra; Lee, Won Sang

2017-04-01

Meltwater stored in ponds and crevasses can weaken and fracture ice shelves, triggering their rapid disintegration. This ice-shelf collapse results in an increased flux of ice from adjacent glaciers and ice streams, thereby raising sea level globally. However, surface rivers forming on ice shelves could potentially export stored meltwater and prevent its destructive effects. Here we present evidence for persistent active drainage networks—interconnected streams, ponds and rivers—on the Nansen Ice Shelf in Antarctica that export a large fraction of the ice shelf’s meltwater into the ocean. We find that active drainage has exported water off the ice surface through waterfalls and dolines for more than a century. The surface river terminates in a 130-metre-wide waterfall that can export the entire annual surface melt over the course of seven days. During warmer melt seasons, these drainage networks adapt to changing environmental conditions by remaining active for longer and exporting more water. Similar networks are present on the ice shelf in front of Petermann Glacier, Greenland, but other systems, such as on the Larsen C and Amery Ice Shelves, retain surface water at present. The underlying reasons for export versus retention remain unclear. Nonetheless our results suggest that, in a future warming climate, surface rivers could export melt off the large ice shelves surrounding Antarctica—contrary to present Antarctic ice-sheet models, which assume that meltwater is stored on the ice surface where it triggers ice-shelf disintegration.

River Ice Data Instrumentation

DTIC Science & Technology

1997-06-01

transmission and storage of data. Fi- nally, recommendations are made for further work in the field of ice data collection. North Atlantic \\N...Missouri River Division (MRD) Kansas City Omaha MRK MRO 7 32 20 11 North Atlantic Division (NAD) Baltimore New York Norfolk Philadelphia... Western 1 r~ T T Ice Thickness U Water Temperature < > Air Temperature i ► Discharge < | Water Stage < [ Ice Areal Coverage a Ice

Flow structure at an ice-covered river confluence

NASA Astrophysics Data System (ADS)

Martel, Nancy; Biron, Pascale; Buffin-Bélanger, Thomas

2017-04-01

River confluences are known to exhibit complex relationships between flow structure, sediment transport and bed-form development. Flow structure at these sites is influenced by the junction angle, the momentum flux ratio (Mr) and bed morphology. In cold regions where an ice cover is present for most of the winter period, the flow structure is also likely affected by the roughness effect of the ice. However, very few studies have examined the impact of an ice cover on the flow structure at a confluence. The aims of this study are (1) to describe the evolution of an ice cover at a river confluence and (2) to characterize and compare the flow structure at a river confluence with and without an ice cover. The field site is a medium-sized confluence (around 40 m wide) between the Mit is and Neigette Rivers in the Bas-Saint-Laurent region, Quebec (Canada). The confluence was selected because a thick ice cover is present for most of the winter allowing for safe field work. Two winter field campaigns were conducted in 2015 and 2016 to obtain ice cover measurements in addition to hydraulic and morphological measurements. Daily monitoring of the evolution of the ice cover was made with a Reconyx camera. Velocity profiles were collected with an acoustic Doppler current profiler (ADCP) to reconstruct the three-dimensional flow structure. Time series of photographs allow the evolution of the ice cover to be mapped, linking the processes leading to the formation of the primary ice cover for each year. The time series suggests that these processes are closely related with both confluence flow zones and hydro-climatic conditions. Results on the thickness of the ice cover from in situ measurements reveal that the ice thickness tends to be thinner at the center of the confluence where high turbulent exchanges take place. Velocity measurements reveal that the ice cover affects velocity profiles by moving the highest velocities towards the center of the profiles. A spatio-temporal conceptual model is presented to illustrate the main differences on the three-dimensional flow structure at the river confluence with and without the ice cover.

Monitoring ice break-up on the Mackenzie River using MODIS data

NASA Astrophysics Data System (ADS)

Muhammad, P.; Duguay, C.; Kang, K.-K.

2016-03-01

The aim of this study was to develop an approach for estimating ice break-up dates on the Mackenzie River (MR) using more than a decade of MODIS Level 3 500 m snow products (MOD/MYD10A1), complemented with 250 m Level 1B radiance products (MOD/MYD02QKM) from the Terra and Aqua satellite platforms. The analysis showed break-up began on average between days of year (DOYs) 115 and 125 and ended between DOYs 145 and 155 over 13 ice seasons (2001-2013), resulting in an average melt duration of ca. 30-40 days. Thermal processes were more important in driving ice break-up south of the MR confluence with the Liard River, while dynamically driven break-up was more important north of the Liard. A comparison of the timing of ice disappearance with snow disappearance from surrounding land areas of the MR with MODIS Level 3 snow products showed varying relationships along the river. Ice-off and snow-off timing were in sync north of the MR-Liard River confluence and over sections of the MR before it enters the Mackenzie Delta, but ice disappeared much later than snow on land in regions where thermal ice break-up processes dominated. MODIS observations revealed that channel morphology is a more important control of ice break-up patterns than previously believed with ice runs on the MR strongly influenced by channel morphology (islands and bars, confluences and channel constriction). Ice velocity estimates from feature tracking were able to be made in 2008 and 2010 and yielded 3-4-day average ice velocities of 1.21 and 1.84 m s-1 respectively, which is in agreement with estimates from previous studies. These preliminary results confirm the utility of daily MODIS data for monitoring ice break-up processes along the Mackenzie River. The addition of optical and synthetic aperture radar data from recent and upcoming satellite missions (e.g. Sentinel-1/2/3 and RADARSAT Constellation) would improve the monitoring of ice break-up in narrower sections of the MR.

Warm Rivers Play Role in Arctic Sea Ice Melt Animation

NASA Image and Video Library

2014-03-05

This frame from a NASA MODIS animation depicts warming sea surface temperatures in the Arctic Beaufort Sea after warm waters from Canada Mackenzie River broke through a shoreline sea ice barrier in summer 2012, enhancing the melting of sea ice.

Ice flood velocity calculating approach based on single view metrology

NASA Astrophysics Data System (ADS)

Wu, X.; Xu, L.

2017-02-01

Yellow River is the river in which the ice flood occurs most frequently in China, hence, the Ice flood forecasting has great significance for the river flood prevention work. In various ice flood forecast models, the flow velocity is one of the most important parameters. In spite of the great significance of the flow velocity, its acquisition heavily relies on manual observation or deriving from empirical formula. In recent years, with the high development of video surveillance technology and wireless transmission network, the Yellow River Conservancy Commission set up the ice situation monitoring system, in which live videos can be transmitted to the monitoring center through 3G mobile networks. In this paper, an approach to get the ice velocity based on single view metrology and motion tracking technique using monitoring videos as input data is proposed. First of all, River way can be approximated as a plane. On this condition, we analyze the geometry relevance between the object side and the image side. Besides, we present the principle to measure length in object side from image. Secondly, we use LK optical flow which support pyramid data to track the ice in motion. Combining the result of camera calibration and single view metrology, we propose a flow to calculate the real velocity of ice flood. At last we realize a prototype system by programming and use it to test the reliability and rationality of the whole solution.

Study on glacier changes from multi-source remote sensing data in the mountainous areas of the upper reaches of Shule River Basin

NASA Astrophysics Data System (ADS)

Zhang, S.; Li, H.

2017-12-01

The changes of glacier area, ice surface elevation and ice storage in the upper reaches of the Shule River Basin were investigated by the Landsat TM series SRTM and stereo image pairs of Third Resources Satellite (ZY-3)from 2000 to 2015. There are 510 glaciers with areas large than 0.01 km2 in 2015, and the glacier area is 435 km2 in the upper reach of Shule River basin. 96 glaciers were disappeared from 2000 to 2015, and the total glacier area decreased by 57.6±2.68km2 (11.7 %). After correcting the elevation difference between ZY-3 DEM and SRTM and aspect, we found that the average ice surface elevation of glaciers reduced by 2.58±0.6m from 2000 to 2015 , with average reduction 0.172 ±0.04m a-1, and the ice storage reduced by 1.277±0.311km3. Elevation variation of ice surface in different sub-regions reflects the complexity of glacier change. The ice storage change calculated from the sum of single glacier area-volume relationship is glacier 1.46 times higher than that estimated from ice surface elevation change, indicating that the global ice storage change estimated from glacier area-volume change probably overestimated. The shrinkage of glacier increased glacier runoff, and led the significant increase of river runoff. The accuracy of projecting the potential glacier change, glacier runoff and river runoff is the key issues of delicacy water resource management in Shule River Basin.

Substantial export of suspended sediment to the global oceans from glacial erosion in Greenland

NASA Astrophysics Data System (ADS)

Overeem, I.; Hudson, B. D.; Syvitski, J. P. M.; Mikkelsen, A. B.; Hasholt, B.; van den Broeke, M. R.; Noël, B. P. Y.; Morlighem, M.

2017-11-01

Limited measurements along Greenland's remote coastline hamper quantification of the sediment and associated nutrients draining the Greenland ice sheet, despite the potential influence of river-transported suspended sediment on phytoplankton blooms and carbon sequestration. Here we calibrate satellite imagery to estimate suspended sediment concentration for 160 proglacial rivers across Greenland. Combining these suspended sediment reconstructions with numerical calculations of meltwater runoff, we quantify the amount and spatial pattern of sediment export from the ice sheet. We find that, although runoff from Greenland represents only 1.1% of the Earth's freshwater flux, the Greenland ice sheet produces approximately 8% of the modern fluvial export of suspended sediment to the global ocean. Sediment loads are highly variable between rivers, consistent with observed differences in ice dynamics and thus with control by glacial erosion. Rivers that originate from deeply incised, fast-moving glacial tongues form distinct sediment-export hotspots: just 15% of Greenland's rivers transport 80% of the total sediment load of the ice sheet. We conclude that future acceleration of melt and ice sheet flow may increase sediment delivery from Greenland to its fjords and the nearby ocean.

Yellow River Icicle Hazard Dynamic Monitoring Using UAV Aerial Remote Sensing Technology

NASA Astrophysics Data System (ADS)

Wang, H. B.; Wang, G. H.; Tang, X. M.; Li, C. H.

2014-02-01

Monitoring the response of Yellow River icicle hazard change requires accurate and repeatable topographic surveys. A new method based on unmanned aerial vehicle (UAV) aerial remote sensing technology is proposed for real-time data processing in Yellow River icicle hazard dynamic monitoring. The monitoring area is located in the Yellow River ice intensive care area in southern BaoTou of Inner Mongolia autonomous region. Monitoring time is from the 20th February to 30th March in 2013. Using the proposed video data processing method, automatic extraction covering area of 7.8 km2 of video key frame image 1832 frames took 34.786 seconds. The stitching and correcting time was 122.34 seconds and the accuracy was better than 0.5 m. Through the comparison of precise processing of sequence video stitching image, the method determines the change of the Yellow River ice and locates accurate positioning of ice bar, improving the traditional visual method by more than 100 times. The results provide accurate aid decision information for the Yellow River ice prevention headquarters. Finally, the effect of dam break is repeatedly monitored and ice break five meter accuracy is calculated through accurate monitoring and evaluation analysis.

The reproductive success of lake herring in habitats near shipping channels and ice-breaking operations in the St. Marys River, Michigan, USA

USGS Publications Warehouse

Blouin, Marc A.; Kostich, M.M.; Todd, T.N.; Savino, J.F.

1998-01-01

A study of the reproductive success of lake herring (Coregonus artedi) in the St. Marys River was conducted in the winters and springs of 1994, 1995, and 1996. The St. Marys River connects Lake Superior to the lower Great Lakes making it an important route for ship traffic. Recent pressure by commercial carriers to extend the shipping season by breaking ice earlier in spring, has raised concerns over the possible adverse effects on lake herring reproduction in the river caused by increased turbidity associated with vessel passage. Lake herring spawn in fall and their eggs overwinter under ice cover on the bottom of the St. Marys River. Hatching occurs in the spring after ice-out when water temperatures rise. Specialized incubators were used to hold fertilized lake herring eggs at four experimental sites, chosen to represent the range of various bottom substrate types of the St. Marys River from boulder rock reefs to soft sediments. In winter, incubators were placed under the ice on the bottom of the river at three sites each year. After ice-out, sites were relocated, and the incubators were retrieved and opened to determine the number of live and dead lake herring eggs and larvae. Survival was consistent from year to year at each site with the lowest survival percentage found at the site with the softest sediments, directly adjacent to the St. Marys River channel and downstream of the mouth of the Charlotte River. River bottom type and geographic location were the most important factors in determining egg survival. Sampling for indigenous larval lake herring was done throughout the spring hatching season in the areas adjacent to the incubator sites using nets and a diver-operated suction sampler. Result indicate that a small population (3) of larval lake herring was present throughout the sampling areas during the springs of 1994, 1995, and 1996 in the St. Marys River.

Flooding on Russia's Lena River

NASA Technical Reports Server (NTRS)

2002-01-01

Nearly every year in the late spring, ice blocks the flow of water at the mouth of the Lena River in northeastern Russia and gives rise to floods across the Siberian plains. This year's floods can be seen in this image taken on June 2, 2002, by the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Terra satellite. The river runs down the left side of the image, and its delta is shrouded in ice (red) at the top of the image. Normally, the river would resemble a thin black line in MODIS imagery. The river, which is Russia's longest, flows 2,641 miles (4,250 kilometers) south to north through Siberia and into the Laptev Sea. In the winter, the river becomes nearly frozen. In the spring, however, water upstream thaws earlier than water at the mouth of the river. As the southern end of the river begins to melt, blocks of ice travel downstream to the still frozen delta, pile up, and often obstruct the flow of water. Flooding doesn't always occur on the same parts of the river. The floods hit further south last year. If the flooding grows severe enough, explosive charges are typically used to break up the ice jams. In these false-color images land areas are a dull, light green or tan, and water is black. Clouds appear pink, and ice comes across as bright red. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

Ice Jams the Ob River

NASA Technical Reports Server (NTRS)

2007-01-01

Russia's Ob River flows from south to north, and each summer, it thaws in the same direction. The result is that an ice jam sits downstream from thawed portions of the river, which is laden with heavy runoff from melted snow. On June 29, 2007, the Moderate Resolution Imaging Spectroradiometer (MODIS) flying on NASA's Terra satellite captured this image of the almost completely thawed Ob River. The scene is typical for early summer. South of the ice jam, the Gulf of Ob is swollen with pent-up run-off, and upstream from that, the river is widened as well. Unable to carve through frozen land, the river has little choice but to overflow its banks. For a comparison of early summer and autumn conditions, see Flooding on the Ob River in the Earth Observatory's Natural Hazards section. Besides the annual overflow, this image captures other circumstances of early summer. Sea ice is retreating from the Kara Sea. A lingering line of snow cover snakes its way along the Ob River, to the west. And while the land is lush and green in the south, it appears barren and brown in the north. Near the mouth of the river and the Kara Sea, the land is cold-adapted tundra, with diminutive plants and a short growing season. Just as the ice plugging the river had yet to thaw in the Far North's short summer, the tundra had not yet to greened up either. In this image it still appears lifeless beige. NASA image courtesy Jeff Schmaltz, MODIS Rapid Response Team, Goddard Space Flight Center

Earth Observations taken by the Expedition 15 Crew

NASA Image and Video Library

2007-04-29

ISS015-E-05624 (29 April 2007) --- The Niagara River, eastern end of Lake Erie and western end of Lake Ontario are featured in this image photographed by an Expedition 15 crewmember on the International Space Station. In contrast, an image photographed by an Expedition 14 crewmember just a month earlier on March 21, 2007 (ISS014-E-17999) shows Lake Erie clogged with ice that is pushed against the shore line by the prevailing weather systems from the west. These two images document the breakup of the Lake Erie ice pack, the unofficial signature of spring for residents of Buffalo and Niagara Falls. During the winter months, the ice collects in Lake Erie and is prevented from flowing down the Niagara River (the international boundary between Ontario, Canada and New York State) by the Lake Erie-Niagara River Ice Boom. The 2,680-meter (8,800-foot) boom, administered by the 1909 Boundary Water Treaty's International Niagara Board of Control, is deployed each December. Operational since 1964, the boom serves several functions: it protects the water intakes for the Niagara River power plants, and minimizes ice runs and ice blockages that can create damage and flooding along the river. At the height of winter, the thickness of the ice at the Buffalo harbor can reach 3.5 meters (12 feet). The removal of the ice boom, usually in early April, is now marked by local celebrations. This year the boom was removed in mid-April, a bit later than usual.

Semi-automated Digital Imaging and Processing System for Measuring Lake Ice Thickness

NASA Astrophysics Data System (ADS)

Singh, Preetpal

Canada is home to thousands of freshwater lakes and rivers. Apart from being sources of infinite natural beauty, rivers and lakes are an important source of water, food and transportation. The northern hemisphere of Canada experiences extreme cold temperatures in the winter resulting in a freeze up of regional lakes and rivers. Frozen lakes and rivers tend to offer unique opportunities in terms of wildlife harvesting and winter transportation. Ice roads built on frozen rivers and lakes are vital supply lines for industrial operations in the remote north. Monitoring the ice freeze-up and break-up dates annually can help predict regional climatic changes. Lake ice impacts a variety of physical, ecological and economic processes. The construction and maintenance of a winter road can cost millions of dollars annually. A good understanding of ice mechanics is required to build and deem an ice road safe. A crucial factor in calculating load bearing capacity of ice sheets is the thickness of ice. Construction costs are mainly attributed to producing and maintaining a specific thickness and density of ice that can support different loads. Climate change is leading to warmer temperatures causing the ice to thin faster. At a certain point, a winter road may not be thick enough to support travel and transportation. There is considerable interest in monitoring winter road conditions given the high construction and maintenance costs involved. Remote sensing technologies such as Synthetic Aperture Radar have been successfully utilized to study the extent of ice covers and record freeze-up and break-up dates of ice on lakes and rivers across the north. Ice road builders often used Ultrasound equipment to measure ice thickness. However, an automated monitoring system, based on machine vision and image processing technology, which can measure ice thickness on lakes has not been thought of. Machine vision and image processing techniques have successfully been used in manufacturing to detect equipment failure and identify defective products at the assembly line. The research work in this thesis combines machine vision and image processing technology to build a digital imaging and processing system for monitoring and measuring lake ice thickness in real time. An ultra-compact USB camera is programmed to acquire and transmit high resolution imagery for processing with MATLAB Image Processing toolbox. The image acquisition and transmission process is fully automated; image analysis is semi-automated and requires limited user input. Potential design changes to the prototype and ideas on fully automating the imaging and processing procedure are presented to conclude this research work.

Hydrological role of large icings within glacierized Sub-Arctic watershed: case study in Upper Duke River valley, Yukon, Canada.

NASA Astrophysics Data System (ADS)

Chesnokova, Anna; Baraer, Michel

2017-04-01

Sub-Arctic glacierized catchments are complex hydrological systems of paramount importance for water resources management as well as for various ecosystem services. Such systems host many climate-sensitive water sources. Among those, icing is an important component as they provide substantial amount of water during the melt season. Moreover, collecting water of different origins during their formation, icings can be seen as an indicator for different water sources and water pathways that remain active during the freezing period. The present study focuses on genesis and dynamics of large icings within both proglacial field and neighboring alpine meadow in Upper Duke River valley, Yukon, in order to i) provide new insights on water sources and pathways within Sub-Arctic glacierized watersheds, and ii) to quantify contribution of icings to the total runoff of those hydrological systems. A multi-approach technique was applied to cope with the high hydrological complexity met in Sub-Arctic mountainous environments. Time series of positions of large river icings within the study area were obtained using Landsat images for the period 1980-2016. Four time-lapse cameras (TLC) were installed in the watershed targeting two proglacial fields and two alpine meadows in order to monitor icing dynamics all year long. Meteorological data was measured by an Automatic Weather Station in the main valley. In addition air temperature and relative humidity were measured at the location of each TLC. Finally, four icings along the Duke River valley, as well as 2 icings in its main tributary were sampled for stable water isotopes, solutes concentrations and total organic carbon. In addition, samples of freezing exclusion precipitates from icing surfaces were taken. Remote sensing data shows the persistence of large icing complexes in the area during last 30 years: icing within proglacial field appear with almost constant position relative to main glacier tongue on the 30 years long period. Absolute position of icings limits is changing however, and is shifting upstream following glacier retreat. TLC show that appearance and growth of icing is correlated with occurrence of milder but still negative temperature episodes. Hydrochemical analysis suggests that main source of water for icing formation within alpine meadow is groundwater, whereas icing formed within proglacial field are fed by both glacier and possibly buried ice water. Thus the multi-technic approach reveals a tight connection of proglacial and river icing formation in Upper Duke River valley with current and past glacier systems: sub-glacial drainage water as well as water from buried ice are collected in a form of icing during mild winter episodes and then are being redistributed to total runoff during ablation season contributing substantially. Moreover, observed relation between icing formation and air temperature regime in the valley suggests that hydrological role of icings in Sub-Arctic glacierized watershed will be subject to changes under changing climate.

Early and abrupt retreat of the Laurentide Ice Sheet margin from the Mackenzie River valley, southern Northwest Territories

NASA Astrophysics Data System (ADS)

Margold, Martin; Froese, Duane G.; Gosse, John C.; Yang, Guang; McKenna, Jillian; Hidy, Alan J.

2017-04-01

The detachment of the Laurentide Ice Sheet margin from the Canadian Cordillera opened the present-day drainage route of the Mackenzie River to the Arctic Ocean and an ice-free corridor that allowed for migration of species between Beringia and the mid-latitudes of North America. The existing ice-margin chronology depicts the southern reach of the Mackenzie River between 61 and 63° N as glaciated until about 13 ka, representing the last portion of the Laurentide Ice Sheet margin abutting the eastern foot of the Cordillera. A substantial retreat of the ice sheet margin in this region has been suggested to have occurred during the subsequent Younger Dryas cold period, despite the fact that in many other regions ice masses stabilised or even re-grew at this time. However, until now, deglacial chronometry for this region and the western LIS margin is sparse and consists mostly of minimum-limiting macrofossil and bulk C-14 ages from organics materials overlying glacial sediment. With the aim to bring new data on the deglaciation history of the Mackenzie River valley, we collected samples for Be-10 exposure dating from glacial erratic boulders in the southern Franklin Mountains that bound the Mackenzie River valley from the east. The sampling elevations ranged between 1480 and 800 m a.s.l., however, the measured ages show only a weak correlation with elevation. Instead, 10 out of 12 measured samples cluster tightly around 15 ka, with the remaining two samples likely containing Be-10 inherited from previous periods of exposure. Our results thus indicate a pre-Younger Dryas rapid down-wasting of the ice sheet surface, which we infer was accompanied by an ice margin retreat to the southeast. The southern reach of the Mackenzie River valley at the eastern foot of the Cordillera was, according to our results, ice free shortly after 15 ka, with the prospect that the ice-free corridor might have opened significantly earlier than hitherto anticipated. Further research is required in the region south of our study area to establish a firm chronological control on the separation of the Cordilleran and Laurentide ice sheets and the opening of the ice free corridor.

Ancient Yedoma carbon loss: primed by ice wedge thaw?

NASA Astrophysics Data System (ADS)

Dowdy, K. L.; Vonk, J. E.; Mann, P. J.; Zimov, N.; Bulygina, E. B.; Davydova, A.; Spencer, R. G.; Holmes, R. M.

2012-12-01

Northeast Siberian permafrost is dominated by frozen Yedoma deposits containing ca. 500 Gt of carbon, nearly a quarter of northern permafrost organic carbon (OC). Yedoma deposits are Pleistocene-age alluvial and/or aeolian accumulations characterized by high ice wedge content (~50%), making them particularly vulnerable to a warming climate and to surface collapse upon thaw. Dissolved OC in streams originating primarily from Yedoma has been shown to be highly biolabile, relative to waters containing more modern OC. The cause of this biolability, however, remains speculative. Here we investigate the influence of ice wedge input upon the bioavailability of Yedoma within streams from as a potential cause of Yedoma carbon biolability upon release into the Kolyma River from the thaw-eroding river exposures of Duvannyi Yar, NE Siberia. We measured biolability on (1) ice wedge, Kolyma, and Yedoma leachate controls; (2) ice wedge and Kolyma plus Yedoma OC (8 g/L); and (3) varying ratios of ice wedge water to Kolyma river water. Biolability assays were conducted using both 5-day BOD (biological oxygen demand) and 11-day BDOC (biodegradable dissolved organic carbon) incubations. We found that ancient DOC in Yedoma soil leachate alone was highly biolabile with losses of 52±0.1% C over a 5-day BOD incubation. Similarly, DOC contained in pure ice wedge water was found to be biolabile, losing 21±0% C during a 5-day BOD incubation. Increased ice wedge contributions led to higher overall C losses in identical Yedoma soil leachates, with 8.9±0.6% losses of Yedoma C with 100% ice wedge water, 7.1±1% (50% ice wedge/ 50% Kolyma) and 5±0.3% with 100% Kolyma River water. We discuss potential mechanisms for the increased loss of ancient C using associated measurements of nutrient availability, carbon quality (CDOM/FDOM) and extracellular enzyme activity rates. Our initial results indicate that ice wedge meltwater forming Yedoma streams makes Yedoma OC more bioavailable than it would be if mixed with Kolyma River water alone, suggesting that leach water origin acts as a control on the turnover of old C. The higher reactivity of Yedoma OC in ice wedge meltwater compared to Kolyma River water suggests that further ice wedge and permafrost thaw in Yedoma deposits will likely result in increased CO2 flux into the atmosphere.

Diffusion model validation and interpretation of stable isotopes in river and lake ice

USGS Publications Warehouse

Ferrick, M.G.; Calkins, D.J.; Perron, N.M.; Cragin, J.H.; Kendall, C.

2002-01-01

The stable isotope stratigraphy of river- and lake-ice archives winter hydroclimatic conditions, and can potentially be used to identify changing water sources or to provide important insights into ice formation processes and growth rates. However, accurate interpretations rely on known isotopic fractionation during ice growth. A one-dimensional diffusion model of the liquid boundary layer adjacent to an advancing solid interface, originally developed to simulate solute rejection by growing crystals, has been used without verification to describe non-equilibrium fractionation during congelation ice growth. Results are not in agreement, suggesting the presence of important uncertainties. In this paper we seek validation of the diffusion model for this application using large-scale laboratory experiments with controlled freezing rates and frequent sampling. We obtained consistent, almost constant, isotopic boundary layer thicknesses over a representative range of ice growth rates on both quiescent and well-mixed water. With the 18O boundary layer thickness from the laboratory, the model successfully quantified reduced river-ice growth rates relative to those of a nearby lake. These results were more representative and easier to obtain than those of a conventional thermal ice-growth model. This diffusion model validation and boundary layer thickness determination provide a powerful tool for interpreting the stable isotope stratigraphy of floating ice. The laboratory experiment also replicated successive fractionation events in response to a freeze-thaw-refreeze cycle, providing a mechanism for apparent ice fractionation that exceeds equilibrium. Analysis of the composition of snow ice and frazil ice in river and lake cores indicated surprising similarities between these ice forms. Published in 2002 by John Wiley & Sons, Ltd.

Sikuliqiruq: Ice dynamics of the Meade river - Arctic Alaska, from freezeup to breakup from time-series ground imagery

USGS Publications Warehouse

Beck, R.A.; Rettig, A.J.; Ivenso, C.; Eisner, Wendy R.; Hinkel, Kenneth M.; Jones, Benjamin M.; Arp, C.D.; Grosse, G.; Whiteman, D.

2010-01-01

Ice formation and breakup on Arctic rivers strongly influence river flow, sedimentation, river ecology, winter travel, and subsistence fishing and hunting by Alaskan Natives. We use time-series ground imagery ofthe Meade River to examine the process at high temporal and spatial resolution. Freezeup from complete liquid cover to complete ice cover ofthe Meade River at Atqasuk, Alaska in the fall of 2008 occurred in less than three days between 28 September and 2 October 2008. Breakup in 2009 occurred in less than two hours between 23:47 UTC on 23 May 2009 and 01:27 UTC on 24 May 2009. All times in UTC. Breakup in 2009 and 2010 was ofthe thermal style in contrast to the mechanical style observed in 1966 and is consistent with a warming Arctic. ?? 2010 Taylor & Francis.

Reconstruction of North American drainage basins and river discharge since the Last Glacial Maximum

NASA Astrophysics Data System (ADS)

Wickert, Andrew D.

2016-11-01

Over the last glacial cycle, ice sheets and the resultant glacial isostatic adjustment (GIA) rearranged river systems. As these riverine threads that tied the ice sheets to the sea were stretched, severed, and restructured, they also shrank and swelled with the pulse of meltwater inputs and time-varying drainage basin areas, and sometimes delivered enough meltwater to the oceans in the right places to influence global climate. Here I present a general method to compute past river flow paths, drainage basin geometries, and river discharges, by combining models of past ice sheets, glacial isostatic adjustment, and climate. The result is a time series of synthetic paleohydrographs and drainage basin maps from the Last Glacial Maximum to present for nine major drainage basins - the Mississippi, Rio Grande, Colorado, Columbia, Mackenzie, Hudson Bay, Saint Lawrence, Hudson, and Susquehanna/Chesapeake Bay. These are based on five published reconstructions of the North American ice sheets. I compare these maps with drainage reconstructions and discharge histories based on a review of observational evidence, including river deposits and terraces, isotopic records, mineral provenance markers, glacial moraine histories, and evidence of ice stream and tunnel valley flow directions. The sharp boundaries of the reconstructed past drainage basins complement the flexurally smoothed GIA signal that is more often used to validate ice-sheet reconstructions, and provide a complementary framework to reduce nonuniqueness in model reconstructions of the North American ice-sheet complex.

Estimation of composite hydraulic resistance in ice-covered alluvial streams

NASA Astrophysics Data System (ADS)

Ghareh Aghaji Zare, Soheil; Moore, Stephanie A.; Rennie, Colin D.; Seidou, Ousmane; Ahmari, Habib; Malenchak, Jarrod

2016-02-01

Formation, propagation, and recession of ice cover introduce a dynamic boundary layer to the top of rivers during northern winters. Ice cover affects water velocity magnitude and distribution, water level and consequently conveyance capacity of the river. In this research, total resistance, i.e., "composite resistance," is studied for a 4 month period including stable ice cover, breakup, and open water stages in Lower Nelson River (LNR), northern Manitoba, Canada. Flow and ice characteristics such as water velocity and depth and ice thickness and condition were measured continuously using acoustic techniques. An Acoustic Doppler Current Profiler (ADCP) and Shallow Water Ice Profiling Sonar (SWIPS) were installed simultaneously on a bottom mount and deployed for this purpose. Total resistance to the flow and boundary roughness are estimated using measured bulk hydraulic parameters. A novel method is developed to calculate composite resistance directly from measured under ice velocity profiles. The results of this method are compared to the measured total resistance and to the calculated composite resistance using formulae available in literature. The new technique is demonstrated to compare favorably to measured total resistance and to outperform previously available methods.

Freshwater and polynya components of the shelf-derived Arctic Ocean halocline in summer 2007 identified by stable oxygen isotopes

NASA Astrophysics Data System (ADS)

Bauch, D.; Rutgers van der Loeff, M.; Andersen, N.; Torres-Valdes, S.; Bakker, K.; Abrahamsen, E.

2011-12-01

With the aim of determining the origin of freshwater in the halocline, fractions of river water and sea-ice meltwater (or brine influence from sea-ice formation) in the upper 150 m were quantified by a combination of salinity and δ18O and nutrients in the Eurasian basins and the Makarov Basin. Our study indicates which layers of the Arctic Ocean halocline are primarily influenced by sea-ice formation in coastal polynyas and which are primarily influenced by sea-ice formation over the open ocean. With the ongoing changes in sea-ice coverage in the Arctic Ocean it can be expected that these processes will change in the immediate future and that the relative contributions to the halocline will change accordingly. Within the Eurasian Basin a west to east oriented front between net melting and production of sea-ice is observed. Outside the Atlantic regime dominated by net sea-ice melting, a pronounced layer influenced by brines released during sea-ice formation is present at about 30 to 50 m water depth with a maximum over the Lomonosov Ridge. The geographically distinct definition of this maximum demonstrates the rapid release and transport of signals from the shelf regions in discrete pulses within the Transpolar Drift. We use the ratio of sea-ice derived brine influence and river water to link the maximum in brine influence within the Transpolar Drift with a pulse of shelf waters from the Laptev Sea likely released in summer 2005. For a distinction of Atlantic and Pacific-derived contributions the initial phosphate corrected for mineralization with oxygen (PO*) and alternatively the nitrate to phosphate ratio (N/P) in each sample were used. While PO*-based assessments systematically underestimate the contribution of Pacific-derived waters, N/P-based calculations overestimate Pacific-derived waters within the Transpolar Drift due to denitrification in bottom sediments of the Laptev Sea. The extent of Pacific-derived water in the Arctic Ocean was approximately limited by the position of the Lomonosov Ridge in 2007. The ratio of sea-ice derived brine influence and river water is roughly constant within each layer of the Arctic Ocean halocline. The correlation between brine influence and river water reveals two clusters that can be assigned to the two main mechanisms of sea-ice formation within the Arctic Ocean. Over the open ocean or in polynyas at the continental slope sea-ice formation results in a linear correlation between brine influence and river water at salinities of ~ 32 to 34. In coastal polynyas in the shallow regions of the Laptev Sea and southern Kara Sea, sea-ice formation transports river water into the shelf's bottom layer due to the close proximity to the river mouths. This process results in a second linear correlation between brine influence and river water at salinities of ~ 30 to 32.

Modelling and Analysis of Hydrodynamics and Water Quality for Rivers in the Northern Cold Region of China

PubMed Central

Tang, Gula; Zhu, Yunqiang; Wu, Guozheng; Li, Jing; Li, Zhao-Liang; Sun, Jiulin

2016-01-01

In this study, the Mudan River, which is the most typical river in the northern cold region of China was selected as the research object; Environmental Fluid Dynamics Code (EFDC) was adopted to construct a new two-dimensional water quality model for the urban sections of the Mudan River, and concentrations of CODCr and NH3N during ice-covered and open-water periods were simulated and analyzed. Results indicated that roughness coefficient and comprehensive pollutant decay rate were significantly different in those periods. To be specific, the roughness coefficient in the ice-covered period was larger than that of the open-water period, while the decay rate within the former period was smaller than that in the latter. In addition, according to the analysis of the simulated results, the main reasons for the decay rate reduction during the ice-covered period are temperature drop, upstream inflow decrease and ice layer cover; among them, ice sheet is the major contributor of roughness increase. These aspects were discussed in more detail in this work. The model could be generalized to hydrodynamic water quality process simulation researches on rivers in other cold regions as well. PMID:27070631

Long-term increases in young-of-the-year growth of Arctic cisco Coregonus autumnalis and environmental influences

USGS Publications Warehouse

von Biela, Vanessa R.; Zimmerman, Christian E.; Moulton, L. L.

2011-01-01

Arctic cisco Coregonus autumnalis young-of-year (YOY) growth was used as a proxy to examine the long-term response of a high-latitude fish population to changing climate from 1978 to 2004. YOY growth increased over time (r2 = 0·29) and was correlated with monthly averages of the Arctic oscillation index, air temperature, east wind speed, sea-ice concentration and river discharge with and without time lags. Overall, the most prevalent correlates to YOY growth were sea-ice concentration lagged 1 year (significant correlations in 7 months; r2 = 0·14-0·31) and Mackenzie River discharge lagged 2 years (significant correlations in 8 months; r2 = 0·13-0·50). The results suggest that decreased sea-ice concentrations and increased river discharge fuel primary production and that life cycles of prey species linking increased primary production to fish growth are responsible for the time lag. Oceanographic studies also suggest that sea ice concentration and fluvial inputs from the Mackenzie River are key factors influencing productivity in the Beaufort Sea. Future research should assess the possible mechanism relating sea ice concentration and river discharge to productivity at upper trophic levels.

A stacking ensemble learning framework for annual river ice breakup dates

NASA Astrophysics Data System (ADS)

Sun, Wei; Trevor, Bernard

2018-06-01

River ice breakup dates (BDs) are not merely a proxy indicator of climate variability and change, but a direct concern in the management of local ice-caused flooding. A framework of stacking ensemble learning for annual river ice BDs was developed, which included two-level components: member and combining models. The member models described the relations between BD and their affecting indicators; the combining models linked the predicted BD by each member models with the observed BD. Especially, Bayesian regularization back-propagation artificial neural network (BRANN), and adaptive neuro fuzzy inference systems (ANFIS) were employed as both member and combining models. The candidate combining models also included the simple average methods (SAM). The input variables for member models were selected by a hybrid filter and wrapper method. The performances of these models were examined using the leave-one-out cross validation. As the largest unregulated river in Alberta, Canada with ice jams frequently occurring in the vicinity of Fort McMurray, the Athabasca River at Fort McMurray was selected as the study area. The breakup dates and candidate affecting indicators in 1980-2015 were collected. The results showed that, the BRANN member models generally outperformed the ANFIS member models in terms of better performances and simpler structures. The difference between the R and MI rankings of inputs in the optimal member models may imply that the linear correlation based filter method would be feasible to generate a range of candidate inputs for further screening through other wrapper or embedded IVS methods. The SAM and BRANN combining models generally outperformed all member models. The optimal SAM combining model combined two BRANN member models and improved upon them in terms of average squared errors by 14.6% and 18.1% respectively. In this study, for the first time, the stacking ensemble learning was applied to forecasting of river ice breakup dates, which appeared promising for other river ice forecasting problems.

Effects of ice formation on hydrology and water quality in the lower Bradley River, Alaska; implications for salmon incubation habitat

USGS Publications Warehouse

Rickman, Ronald L.

1998-01-01

A minimum flow of 40 cubic feet per second is required in the lower Bradley River, near Homer, Alaska, from November 2 to April 30 to ensure adequate habitat for salmon incubation. The study that determined this minimum flow did not account for the effects of ice formation on habitat. The limiting factor for determining the minimal acceptable flow limit appears to be stream-water velocity. The minimum short-term flow needed to ensure adequate salmon incubation habitat when ice is present is about 30 cubic feet per second. For long-term flows, 40 cubic feet per second is adequate when ice is present. Long-term minimum discharge needed to ensure adequate incubation habitat--which is based on mean velocity alone--is as follows: 40 cubic feet per second when ice is forming; 35 cubic feet per second for stable and eroding ice conditions; and 30 cubic feet per second for ice-free conditions. The effects of long-term streamflow less than 40 cubic feet per second on fine-sediment deposition and dissolved-oxygen interchange could not be extrapolated from the data. Hydrologic properties and water-quality data were measured in winter only from March 1993 to April 1998 at six transects in the lower Bradley River under three phases of icing: forming, stable, and eroding. Discharge in the lower Bradley River ranged from 33.3 to 73.0 cubic feet per second during all phases of ice formation and ice conditions, which ranged from ice free to 100 percent ice cover. Hydrostatic head was adequate for habitat protection for all ice phases and discharges. Mean stream velocity was adequate for all but one ice-forming episode. Velocity distribution within each transect varied significantly from one sampling period to the next. No relation was found between ice phase, discharge, and wetted perimeter. Intragravel-water temperature was slightly warmer than surface-water temperature. Surface- and intragravel-water dissolved-oxygen levels were adequate for all ice phases and discharges. No apparent relation was found between dissolved-oxygen levels and streamflow or ice conditions. Fine-sediment deposition was greatest at the downstream end of the study reach because of low shear velocities and tide-induced deposition. Dissolved-oxygen interchange was adequate for all discharges and ice conditions. Stranding potential of salmon fry was found to be low throughout the study reach. Minimum flows from the fish-water bypass needed to maintain 40 cubic feet per second in the lower Bradley River are estimated.

Proglacial River Reveals Substantial Greenland Ice Sheet Climate Sensitivity and Meltwater Routing Delays

NASA Astrophysics Data System (ADS)

van As, D.; Mikkelsen, A. B.; Holtegaard Nielsen, M.; Claesson Liljedahl, L.; Lindback, K.; Pitcher, L. H.; Hasholt, B.

2016-12-01

A 12.000 km2 area of the Greenland ice sheet discharges meltwater via the proglacial Watson River in west Greenland. In a ten-year time span of continuous monitoring (2006-2015), the river discharged 3.8 km3 to 11.2 km3 yr-1. The large interannual variability is for an important part explained by hypsometric amplification: the flattening of the ice sheet with elevation adds 70% meltwater discharge sensitivity to atmospheric temperature. Comparing river discharge with ice sheet surface meltwater production from an observation-based surface mass balance model we quantify multiple-day routing delays for meltwater transit through the supra-, en-, sub- and proglacial system. This delay increases with ice sheet surface elevation: on average five days for surface water at the previous-known equilibrium line altitude (ELA) of ca. 1550 m, and seven days at the 2009-2015 ELA of ca. 1800 m above sea level. A flooding of the Kangerlussuaq bridge as in July 2012 thus requires a multi-day high-melt episode and can therefore be anticipated by in-situ monitoring of ice sheet melt. No evidence of significant en- or subglacial meltwater retention is found.

Endmembers of Ice Shelf Melt

NASA Astrophysics Data System (ADS)

Boghosian, A.; Child, S. F.; Kingslake, J.; Tedesco, M.; Bell, R. E.; Alexandrov, O.; McMichael, S.

2017-12-01

Studies of surface melt on ice shelves have defined a spectrum of meltwater behavior. On one end the storage of meltwater in persistent surface ponds can trigger ice shelf collapse as in the 2002 event leading to the disintegration of the Larsen B Ice Shelf. On the other, meltwater export by rivers can stabilize an ice shelf as was recently shown on the Nansen Ice Shelf. We explore this dichotomy by quantifying the partitioning between stored and transported water on two glaciers adjacent to floating ice shelves, Nimrod (Antarctica) and Peterman (Greenland). We analyze optical satellite imagery (LANDSAT, WorldView), airborne imagery (Operation IceBridge, Trimetrogon Aerial Phototography), satellite radar (Sentinel-1), and digital elevation models (DEMs) to categorize surface meltwater fate and map the evolution of ice shelf hydrology and topographic features through time. On the floating Peterman Glacier tongue a sizable river exports water to the ocean. The surface hydrology of Nimrod Glacier, geometrically similar to Peterman but with ten times shallower surface slope, is dominated by storage in surface lakes. In contrast, the Nansen has the same surface slope as Nimrod but transports water through surface rivers. Slope alone is not the sole control on ice shelf hydrology. It is essential to track the storage and transport volumes for each of these systems. To estimate water storage and transport we analyze high resolution (40 cm - 2 m) modern and historical DEMs. We produce historical (1957 onwards) DEMs with structure-from-motion photogrammetry. The DEMs are used to constrain water storage potential estimates of observed basins and water routing/transport potential. We quantify the total volume of water stored seasonally and interannually. We use the normalize difference water index to map meltwater extent, and estimate lake water depth from optical data. We also consider the role of stored water in subsurface aquifers in recharging surface water after observing a pond and river reemerge after apparently freezing during the 2016-17 melt season. Using the ponds/rivers endmember scheme helps us to constrain the role storage and transport play on stabilizing ice shelves. By extending this analysis to other ice tongues and shelves we can better understand their vulnerability to a warming world.

Dynamics of suspended sediment plumes in Lake Ontario

NASA Technical Reports Server (NTRS)

Pluhowski, E. J. (Principal Investigator)

1974-01-01

The author has identified the following significant results. Although turbidity plumes in Lake Ontario are usually not visible during the winter, meteorologic and hydrologic events may combine to ensure their detection. The clearly defined Niagara River plume of January 25, 1974, was the result of turbid water entering the river at its source near the eastern end of Lake Erie. A persistent southwest wind mild temperature resulted in a pile-up of ice free but turbid water at the source of the Niagara River where the highly colored water entered the river. Upon discharge into Lake Ontario, the Niagara River water appears several shades lighter in tone than the ambient lake water. On February 12, 1974, eastward moving ice floes along the Ontario shoreline were forced to move around the hydraulic barrier created by the Niagara River jet. As a result the Niagara River plume was clearly portrayed by a halo-like band of slush ice borne by wind-driven nearshore currents.

Interdisciplinary approach to hydrological hazard mitigation and disaster response and effects of climate change on the occurrence of flood severity in central Alaska

NASA Astrophysics Data System (ADS)

Kontar, Y. Y.; Bhatt, U. S.; Lindsey, S. D.; Plumb, E. W.; Thoman, R. L.

2015-06-01

In May 2013, a massive ice jam on the Yukon River caused flooding that destroyed much of the infrastructure in the Interior Alaska village of Galena and forced the long-term evacuation of nearly 70% of its residents. This case study compares the communication efforts of the out-of-state emergency response agents with those of the Alaska River Watch program, a state-operated flood preparedness and community outreach initiative. For over 50 years, the River Watch program has been fostering long-lasting, open, and reciprocal communication with flood prone communities, as well as local emergency management and tribal officials. By taking into account cultural, ethnic, and socioeconomic features of rural Alaskan communities, the River Watch program was able to establish and maintain a sense of partnership and reliable communication patterns with communities at risk. As a result, officials and residents in these communities are open to information and guidance from the River Watch during the time of a flood, and thus are poised to take prompt actions. By informing communities of existing ice conditions and flood threats on a regular basis, the River Watch provides effective mitigation efforts in terms of ice jam flood effects reduction. Although other ice jam mitigation attempts had been made throughout US and Alaskan history, the majority proved to be futile and/or cost-ineffective. Galena, along with other rural riverine Alaskan communities, has to rely primarily on disaster response and recovery strategies to withstand the shock of disasters. Significant government funds are spent on these challenging efforts and these expenses might be reduced through an improved understanding of both the physical and climatological principals behind river ice breakup and risk mitigation. This study finds that long term dialogue is critical for effective disaster response and recovery during extreme hydrological events connected to changing climate, timing of river ice breakup, and flood occurrence in rural communities of the Far North.

Reduced Duration of Ice Cover in Swedish Lakes and Rivers

NASA Astrophysics Data System (ADS)

AghaKouchak, A.; Hallerback, S. A. M.; Stensen, K.; David, G.; Persson, M.

2016-12-01

The worlds freshwater systems are one of the most altered ecosystems on earth. Climate change introduces additional stresses on such systems, and this study presents an example of such change in an investigation of ice cover duration in Swedish lakes and rivers. In situ observations from over 750 lakes and rivers in Sweden were analyzed, with some records dating back to the beginning of the 18th century. Results show that ice duration significantly decreased over the last century. Change in ice duration is affected by later freeze as well as (more dominantly) earlier breakup dates. Additionally, since the late 1980's there has been an increase of extreme events, meaning years with extremely short duration of ice cover. The affect of temperature on the system was also examined. Using 113 years of temperature data, we empirically show how temperature changes affect the ice duration in lakes at different latitudes as well as dependent on lake area, volume and depth.

Flooding of the Taz, Pur, and Yenisey Rivers, Russia

NASA Technical Reports Server (NTRS)

2002-01-01

Each spring and summer, rivers across Siberia experience flooding as the waters in the south begin to melt and run before the ice has retreated from the northern limits. The ice causes jams which are sometimes loosened up using explosives. This pair of MODIS images from June 18, 2002, shows flooding on the Pur (left), Taz (center), and Yenisey (right) Rivers in central Siberia. In the false-color image, ice and snow are red, clouds are white, water is black, and vegetation is green. Bare soil is brown. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

Long-term increases in young-of-the-year growth of Arctic cisco Coregonus autumnalis and environmental influences

USGS Publications Warehouse

Von Biela, V.R.; Zimmerman, C.E.; Moulton, L.L.

2011-01-01

Arctic cisco Coregonus autumnalis young-of-year (YOY) growth was used as a proxy to examine the long-term response of a high-latitude fish population to changing climate from 1978 to 2004. YOY growth increased over time (r2 = 0??29) and was correlated with monthly averages of the Arctic oscillation index, air temperature, east wind speed, sea-ice concentration and river discharge with and without time lags. Overall, the most prevalent correlates to YOY growth were sea-ice concentration lagged 1 year (significant correlations in 7 months; r2 = 0??14-0??31) and Mackenzie River discharge lagged 2 years (significant correlations in 8 months; r2 = 0??13-0??50). The results suggest that decreased sea-ice concentrations and increased river discharge fuel primary production and that life cycles of prey species linking increased primary production to fish growth are responsible for the time lag. Oceanographic studies also suggest that sea ice concentration and fluvial inputs from the Mackenzie River are key factors influencing productivity in the Beaufort Sea. Future research should assess the possible mechanism relating sea ice concentration and river discharge to productivity at upper trophic levels. Journal of Fish Biology ?? 2010 The Fisheries Society of the British Isles. No claim to original US government works.

Snow and ice volume on Mount Spurr Volcano, Alaska, 1981

USGS Publications Warehouse

March, Rod S.; Mayo, Lawrence R.; Trabant, Dennis C.

1997-01-01

Mount Spurr (3,374 meters altitude) is an active volcano 130 kilometers west of Anchorage, Alaska, with an extensive covering of seasonal and perennial snow, and glaciers. Knowledge of the volume and distribution of snow and ice on a volcano aids in assessing hydrologic hazards such as floods, mudflows, and debris flows. In July 1981, ice thickness was measured at 68 locations on the five main glaciers of Mount Spurr: 64 of these measurements were made using a portable 1.7 megahertz monopulse ice-radar system, and 4 measurements were made using the helicopter altimeter where the glacier bed was exposed by ice avalanching. The distribution of snow and ice derived from these measurements is depicted on contour maps and in tables compiled by altitude and by drainage basins. Basal shear stresses at 20 percent of the measured locations ranged from 200 to 350 kilopascals, which is significantly higher than the 50 to 150 kilopascals commonly referred to in the literature as the 'normal' range for glaciers. Basal shear stresses higher than 'normal' have also been found on steep glaciers on volcanoes in the Cascade Range in the western United States. The area of perennial snow and ice coverage on Mount Spurr was 360 square kilometers in 1981, with an average thickness of 190?50 meters. Seasonal snow increases the volume about 1 percent and increases the area about 30 percent with a maximum in May or June. Runoff from Mount Spurr feeds the Chakachatna River and the Chichantna River (a tributary of the Beluga River). The Chakachatna River drainage contains 14 cubic kilometers of snow and ice and the Chichantna River drainage contains 53 cubic kilometers. The snow and ice volume on the mountain was 67?17 cubic kilometers, approximately 350 times more snow and ice than was on Mount St. Helens before its May 18, 1980, eruption, and 15 times more snow and ice than on Mount Rainier, the most glacierized of the measured volcanoes in the Cascade Range. On the basis of these relative quantities, hazard-producing glaciovolcanic phenomena at Mount Spurr could be significantly greater than similar phenomena at Cascade Volcanoes.

Hydrologic conditions and hazards in the Kennicott River basin, Wrangell-St. Elias National Park Preserve, Alaska

USGS Publications Warehouse

Rickman, R.L.; Rosenkrans, D.S.

1997-01-01

McCarthy, Alaska, is on the Kennicott River, about 1 mile from the terminus of Kennicott Glacier in the Wrangell-St. Elias National Park and Preserve. Most visitors to McCarthy and the park cross the West Fork Kennicott River using a hand-pulled tram and cross the East Fork Kennicott River on a temporary footbridge. Outburst floods from glacier-dammed lakes result in channel erosion, aggradation, and migration of the Kennicott River, which disrupt transportation links, destroy property, and threaten life. Hidden Creek Lake, the largest of six glacier-dammed lakes in the Kennicott River Basin, has annual outbursts that cause the largest floods on the Kennicott River. Outbursts from Hidden Creek Lake occur from early fall to mid-summer, and lake levels at the onset of the outbursts have declined between 1909 and 1995. Criteria for impending outbursts for Hidden Creek Lake include lake stage near or above 3,000 to 3,020 feet, stationary or declining lake stage, evidence of recent calving of large ice blocks from the ice margin, slush ice and small icebergs stranded on the lakeshore, and fresh fractures in the ice-margin region. The lower Kennicott Glacier has thinned and retreated since about 1860. The East and West Fork Kennicott River channels migrated in response to changes in the lower Kennicott Glacier. The largest channel changes occur during outburst floods from Hidden Creek Lake, whereas channel changes from the other glacier-dammed lake outbursts are small. Each year, the West Fork Kennicott River conveys a larger percentage of the Kennicott Glacier drainage than it did the previous year. Outburst floods on the Kennicott River cause the river stage to rise over a period of several hours. Smaller spike peaks have a very rapid stage rise. Potential flood magnitude was estimated by combining known maximum discharges from Hidden Creek Lake and Lake Erie outburst floods with a theoretical large regional flood. Flood hazard areas at the transportation corridor were delineated, and possible future geomorphological changes were hypothesized. McCarthy, Alaska, is on the Kennicott River, about 1 mile from the terminus of Kennicott Glacier in the Wrangell-St. Elias National Park and Preserve. Most visitors to McCarthy and the park cross the West Fork Kennicott River using a hand-pulled tram and cross the East Fork Kennicott River on a temporary footbridge. Outburst floods from glacier-dammed lakes result in channel erosion, aggradation, and migration of the Kennicott River, which disrupt transportation links, destroy property, and threaten life. Hidden Creek Lake, the largest of six glacier-dammed lakes in the Kennicott River Basin, has annual outbursts that cause the largest floods on the Kennicott River. Outbursts from Hidden Creek Lake occur from early fall to mid-summer, and lake levels at the onset of the outbursts have declined between 1909 and 1995. Criteria for impending outbursts for Hidden Creek Lake include lake stage near or above 3,000 to 3,020 feet, stationary or declining lake stage, evidence of recent calving of large ice blocks from the ice margin, slush ice and small icebergs stranded on the lakeshore, and fresh fractures in the ice-margin region. The lower Kennicott Glacier has thinned and retreated since about 1860. The East and West Fork Kennicott River channels migrated in response to changes in the lower Kennicott Glacier. The largest channel changes occur during outburst floods from Hidden Creek Lake, whereas channel changes from the other glacier-dammed lake outbursts are small. Each year, the West Fork Kennicott River conveys a larger percentage of the Kennicott Glacier drainage than it did the previous year. Outburst floods on the Kennicott River cause the river stage to rise over a period of several hours. Smaller spike peaks have a very rapid stage rise. Potential flood magnitude was estimated by combining known maximum discharges from Hidden Creek Lake and Lake Erie outburst floods with

The Role of Basal Channels in Ice Shelf Calving.

NASA Astrophysics Data System (ADS)

Dow, C. F.; Lee, W. S.; Greenbaum, J. S.; Greene, C. A.; Blankenship, D. D.; Poinar, K.; Forrest, A.; Young, D. A.; Zappa, C. J.

2017-12-01

Increased rates of ice shelf break-up drives acceleration of grounded glacial ice into the ocean, resulting in sea-level rise. Ice shelves are vulnerable to thinning, which make them more susceptible to calving. Here, we examine basal channels under three ice shelves that locally thin the ice and drive formation of transverse ice shelf fractures. The basal channels also cause surface depressions due to hydrostatic buoyancy effects and can draw in surface water to form rivers. These rivers exacerbate thinning by surface melting and hydraulic loading, and can accelerate rifting when they flow into the transverse fractures. Our investigation focuses on Nansen Ice Shelf in the Ross Sea Embayment, East Antarctica. We use ice-sounding radar and single-beam laser altimeter data from two aerogeophysical campaigns conducted in 2011 and 2014, ice surface DEM reconstruction, and satellite imagery analysis, to examine the role of a substantial basal channel in the stability of this ice shelf. Nansen Ice Shelf calved two large icebergs totaling 214 km2 in area in April 2016. The transverse fracture that eventually rifted to form these icebergs initiated directly over the basal channel in 1987. In years when surface water formed on Nansen Ice Shelf, a river flowed into the transverse fracture. In November 2016, we identified a new fracture over the basal channel during in-situ data collection. We compare the Nansen Ice Shelf fractures with those at other vulnerable ice-shelf systems, including Petermann Glacier in Greenland and Totten Glacier in East Antarctica, to evaluate the role that basal channels may play in simultaneous basal and surface weakening and their consequent effect on ice-shelf rifting and stability.

Disruption of Drift glacier and origin of floods during the 1989-1990 eruptions of Redoubt Volcano, Alaska

USGS Publications Warehouse

Trabant, D.C.; Waitt, R.B.; Major, J.J.

1994-01-01

Melting of snow and glacier ice during the 1989-1990 eruption of Redoubt Volcano caused winter flooding of the Drift River. Drift glacier was beheaded when 113 to 121 ?? 106 m3 of perennial snow and ice were mechanically entrained in hot-rock avalanches and pyroclastic flows initiated by the four largest eruptions between 14 December 1989 and 14 March 1990. The disruption of Drift glacier was dominated by mechanical disaggregation and entrainment of snow and glacier ice. Hot-rock avalanches, debris flows, and pyroclastic flows incised deep canyons in the glacier ice thereby maintaining a large ice-surface area available for scour by subsequent flows. Downvalley flow rheologies were transformed by the melting of snow and ice entrained along the upper and middle reaches of the glacier and by seasonal snowpack incorporated from the surface of the lower glacier and from the river valley. The seasonal snowpack in the Drift River valley contributed to lahars and floods a cumulative volume equivalent to about 35 ?? 106 m3 of water, which amounts to nearly 30% of the cumulative flow volume 22 km downstream from the volcano. The absence of high-water marks in depressions and of ice-collapse features in the glacier indicated that no large quantities of meltwater that could potentially generate lahars were stored on or under the glacier; the water that generated the lahars that swept Drift River valley was produced from the proximal, eruption-induced volcaniclastic flows by melting of snow and ice. ?? 1994.

Simulation of flow and habitat conditions under ice, Cache la Poudre River - January 2006

USGS Publications Warehouse

Waddle, Terry

2007-01-01

The objectives of this study are (1) to describe the extent and thickness of ice cover, (2) simulate depth and velocity under ice at the study site for observed and reduced flows, and (3) to quantify fish habitat in this portion of the mainstem Cache la Poudre River for the current winter release schedule as well as for similar conditions without the 0.283 m3/s winter release.

Long-term increases in young-of-the-year growth of Arctic cisco Coregonus autumnalis and environmental influences.

PubMed

von Biela, V R; Zimmerman, C E; Moulton, L L

2011-01-01

Arctic cisco Coregonus autumnalis young-of-year (YOY) growth was used as a proxy to examine the long-term response of a high-latitude fish population to changing climate from 1978 to 2004. YOY growth increased over time (r² = 0·29) and was correlated with monthly averages of the Arctic oscillation index, air temperature, east wind speed, sea-ice concentration and river discharge with and without time lags. Overall, the most prevalent correlates to YOY growth were sea-ice concentration lagged 1 year (significant correlations in 7 months; r² = 0·14-0·31) and Mackenzie River discharge lagged 2 years (significant correlations in 8 months; r² = 0·13-0·50). The results suggest that decreased sea-ice concentrations and increased river discharge fuel primary production and that life cycles of prey species linking increased primary production to fish growth are responsible for the time lag. Oceanographic studies also suggest that sea ice concentration and fluvial inputs from the Mackenzie River are key factors influencing productivity in the Beaufort Sea. Future research should assess the possible mechanism relating sea ice concentration and river discharge to productivity at upper trophic levels. Journal of Fish Biology © 2010 The Fisheries Society of the British Isles. No claim to original US government works.

How Rapid Change Affects Deltas in the Arctic Region

NASA Astrophysics Data System (ADS)

Overeem, I.; Bendixen, M.

2017-12-01

Deltas form where the river drains into the ocean. Consequently, delta depositional processes are impacted by either changes in the respective river drainage basin or by changes in the regional marine environment. In a warming Arctic region rapid change has occurred over the last few decades in both the terrestrial domain as well as in the marine domain. Important terrestrial controls include 1) change in permafrost possibly destabilizing river banks, 2) strong seasonality of river discharge due to a short melting season, 3) high sediment supply if basins are extensively glaciated, 4) lake outbursts and ice jams favoring river flooding. Whereas in the Arctic marine domain sea ice loss promotes wave and storm surge impact, and increased longshore transport. We here ask which of these factors dominate any morphological change in Arctic deltas. First, we analyze hydrological data to assess change in Arctic-wide river discharge characteristics and timing, and sea ice concentration data to map changes in sea ice regime. Based on this observational analysis we set up a number of scenarios of change. We then model hypothetical small-scale delta formation considering change in these primary controls by setting up a numerical delta model, and combining it dynamically with a permafrost model. We find that for typical Greenlandic deltas changes in river forcing due to ice sheet melt dominate the morphological change, which is corroborated by mapping of delta progradation from aerial photos and satellite imagery. Whereas in other areas, along the North Slope and the Canadian Arctic small deltas are more stable or experienced retreat. Our preliminary coupled model allows us to further disentangle the impact of major forcing factors on delta evolution in high-latitude systems.

Late Quaternary Glaciation of the Naches River Drainage Basin, Washington Cascades

NASA Astrophysics Data System (ADS)

Sheffer, H. B.; Goss, L.; Shimer, G.; Carson, R. J.

2014-12-01

The Naches River drainage basin east of Mount Rainer includes tributary valleys of the Little Naches, American, Bumping, and Tieton rivers. An investigation of surface boulder frequency, weathering rind thicknesses, and soil development on moraines in these valleys identified two stages of Pleistocene glaciations in the American, Bumping, and Tieton drainages, followed by Neoglaciation. These stages include a more extensive early glaciation (Hayden Creek?), and the later Evans Creek Glaciation (25-15 ka). Thick forest cover, limited road cuts, and widespread post-glacial mass wasting hamper efforts to determine the maximum extent of glaciation. However, glacial striations at Chinook Pass, moraine complexes in the vicinity of Goose Egg Mountain, ice-transported boulders and striations on Pinegrass Ridge, and a boulder field possibly derived from an Evans Creek jökulhaup in the Tieton River valley, all point to extensive Pleistocene ice in the central tributaries of the Naches River. Lowest observed ice elevations in the Tieton (780 m), Bumping (850 m), and American (920 m) drainages increase towards the north, while glacial lengths decrease from 40 to 28 km. The Little Naches is the northernmost drainage in the study, but despite a maximum elevation (1810 m) that exceeds the floor of ice caps to the south, glacially-derived sediments are not evident and the surrounding peaks lack cirques. The absence of ice in the Little Naches drainage, along with the systematic northward change in glacial length and lowest observed ice elevations in the other drainages, are likely due to a precipitation shadow northeast of Mount Rainier. In contrast, the source of glacial ice in the Tieton drainage to the southeast was the Goat Rocks peaks. Ground-based study of neoglacial moraines and analysis of 112 years of topographic maps and satellite imagery point to rapid retreat of the remaining Goat Rocks glaciers following the Little Ice Age.

Flooding of the Ob and Irtysh Rivers, Russia

NASA Technical Reports Server (NTRS)

2002-01-01

These images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite shows the cause and effect of the large-scale seasonal flooding experienced on rivers throughout Siberia each year. Because many Siberian rivers flow from south to north, they flood regularly in the spring as meltwater from southern latitudes backs up against the still-frozen northern reaches of the rivers.These images show the Ob' River on the western edge of the Central Siberian Plateau. The images from June 20, 2002, show the mouth of the Ob' River (large river at left) where it empties into Kara Sea. In the false-color image, Vegetation appears in bright green, water appears dark blue or black, and ice appears bright blue. The ice is still choking the river's outlet to the sea.The effect of this ice block on the more southern stretches of the river can be seen in the images captured on June 17. In the false-color image, water is black, vegetation is in shades of gold and green, and clouds are pale orange. In the northernmost portion of the Ob' visible in this image (the Ob' runs southeast to northwest in the image), what is normally a fine mesh of braided streams and branches of the river channel has become almost a lake in places. The flood waters have engorged the river to 52 kilometers (32 miles) wide in places. Rivers can back up for hundreds of miles, and cause devastating flooding for towns and villages along the banks. Often, explosives are dropped into ice jams in an effort to free the river and give the flood waters a chance to escape. The spring and summer floods of 2002 have proven to be quite severe and perhaps as many as 100,000 people have been affected across the country. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

Mouth of the Ob River, Russia

NASA Technical Reports Server (NTRS)

2002-01-01

These images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite shows the cause and effect of the large-scale seasonal flooding experienced on rivers throughout Siberia each year. Because many Siberian rivers flow from south to north, they flood regularly in the spring as meltwater from southern latitudes backs up against the still-frozen northern reaches of the rivers.These images show the Ob' River on the western edge of the Central Siberian Plateau. The images from June 20, 2002, show the mouth of the Ob' River (large river at left) where it empties into Kara Sea. In the false-color image, Vegetation appears in bright green, water appears dark blue or black, and ice appears bright blue. The ice is still choking the river's outlet to the sea.The effect of this ice block on the more southern stretches of the river can be seen in the images captured on June 17. In the false-color image, water is black, vegetation is in shades of gold and green, and clouds are pale orange. In the northernmost portion of the Ob' visible in this image (the Ob' runs southeast to northwest in the image), what is normally a fine mesh of braided streams and branches of the river channel has become almost a lake in places. The flood waters have engorged the river to 52 kilometers (32 miles) wide in places. Rivers can back up for hundreds of miles, and cause devastating flooding for towns and villages along the banks. Often, explosives are dropped into ice jams in an effort to free the river and give the flood waters a chance to escape. The spring and summer floods of 2002 have proven to be quite severe and perhaps as many as 100,000 people have been affected across the country. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

Ice Jam Flooding and Mitigation: Lower Platte River Basin, Nebraska,

DTIC Science & Technology

1996-01-01

providing much valuable information about ice jam locations and dates. The contents of this report are not to be used for advertising or promotional...52 v Ice Jam Flooding and Mitigation Lower Platte River Basin, Nebraska KATHLEEN D. WHITE AND ROGER L. KAY INTRODUCTION with a...depth below 49 50 I ’ I I I Depth of Charge Below Bottom of Ice Sheet 40- N 0 ft 11 0.6 - 0 1.6 7: V 2.5 .0 -30t- A 3.3 •:Az 6.6 2l) - 3.0 0 20- 0 L

50 CFR 36.39 - Public use.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., and Swanson Lakes are only open for sport ice fishing. Andy Simons Unit Emerald Lake Green Lake Harvey... sport ice fishing. South of Sterling Highway Headquarters Lake is restricted to administrative use only..., Chickaloon (upstream of river mile 7.5), Killey, and Fox Rivers. (v) A “no-wake” restriction applies to...

50 CFR 36.39 - Public use.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., and Swanson Lakes are only open for sport ice fishing. Andy Simons Unit Emerald Lake Green Lake Harvey... sport ice fishing. South of Sterling Highway Headquarters Lake is restricted to administrative use only..., Chickaloon (upstream of river mile 7.5), Killey, and Fox Rivers. (v) A “no-wake” restriction applies to...

50 CFR 36.39 - Public use.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., and Swanson Lakes are only open for sport ice fishing. Andy Simons Unit Emerald Lake Green Lake Harvey... sport ice fishing. South of Sterling Highway Headquarters Lake is restricted to administrative use only..., Chickaloon (upstream of river mile 7.5), Killey, and Fox Rivers. (v) A “no-wake” restriction applies to...

Bearing Capacity Tests on Ice Reinforced With Geogrid

DTIC Science & Technology

1992-12-01

reinforce an ice bridge on rivers, lakes and oceans every winter in cold re- the Imjin River in Korea; Carnes (1964) reports that gions around the...increased the flexural aircraft in World War U. Although this "Pykrete," strength up to 31%. Creep tests on ice beams with as it was called, never was used...The Second World War , Clos- CONCLUSIONS ing the Ring, vol. 5. Boston: Houghton Mifflin, pp. 75-76. Thebearingcapacity testsconductedinCRREL’s

Evaporation of ice in planetary atmospheres: Ice-covered rivers on Mars

NASA Technical Reports Server (NTRS)

Wallace, D.; Sagan, C.

1978-01-01

The evaporation rate of water ice on the surface of a planet with an atmosphere involves an equilibrium between solar heating and radiative and evaporative cooling of the ice layer. The thickness of the ice is governed principally by the solar flux which penetrates the ice layer and then is conducted back to the surface. Evaporation from the surface is governed by wind and free convection. In the absence of wind, eddy diffusion is caused by the lower density of water vapor in comparison to the density of the Martian atmosphere. For mean martian insolations, the evaporation rate above the ice is approximately 10 to the minus 8th power gm/sq cm/s. Evaporation rates are calculated for a wide range of frictional velocities, atmospheric pressures, and insolations and it seems clear that at least some subset of observed Martian channels may have formed as ice-chocked rivers. Typical equilibrium thicknesses of such ice covers are approximately 10m to 30 m; typical surface temperatures are 210 to 235 K.

Mineral precipitation in north slope aufeis

NASA Technical Reports Server (NTRS)

Hall, D. K.

1978-01-01

The Canning and Shaviovik river aufeis fields were studied on the ground and with aircraft data. Powdered calcium carbonate (CaCO3) patches, a few cm in thickness, were found in discrete locations on both aufeis fields. This is indicative of chemical weathering of limestone bedrock which is known to underlie much of the eastern arctic coastal plain of Alaska. Spring or river water which remains unfrozen throughout much of the winter carries CaCO3 in solution; as the river ice freezes more deeply the CaCO3 in solution is forced upwards through cracks in the river ice. Upon exposure to the cold air CaCO3 is excluded as the water freezes, forming successive layers during aufeis growth. In the melt season CaCO3, slush/powder accumulates in patches on top of the ice as the aufeis melts downward.

The influence of the hydrologic cycle on the extent of sea ice with climatic implications

NASA Technical Reports Server (NTRS)

Dean, Ken; Gosink, Joan

1991-01-01

The role was analyzed of the hydrologic cycle on the distribution of sea ice, and its influence on forcings and fluxes between the marine environment and the atmosphere. River discharge plays a significant role in degrading the sea ice before any melting occurs elsewhere along the coast. The influence is considered of river discharge on the albedo, thermal balance, and distribution of sea ice. Quantitative atmospheric-hydrologic models are being developed to describe these processes in the coastal zone. Input for the models will come from satellite images, hydrologic data, and field observations. The resulting analysis provides a basis for the study of the significance of the hydrologic cycle throughout the Arctic Basin and its influence on the regional climate as a result of possible climatic scenarios. The area offshore from the Mackenzie River delta was selected as the study area.

Classification of freshwater ice conditions on the Alaskan Arctic Coastal Plain using ground penetrating radar and TerraSAR-X satellite data

USGS Publications Warehouse

Jones, Benjamin M.; Gusmeroli, Alessio; Arp, Christopher D.; Strozzi, Tazio; Grosse, Guido; Gaglioti, Benjamin V.; Whitman, Matthew S.

2013-01-01

Arctic freshwater ecosystems have responded rapidly to climatic changes over the last half century. Lakes and rivers are experiencing a thinning of the seasonal ice cover, which may increase potential over-wintering freshwater habitat, winter water supply for industrial withdrawal, and permafrost degradation. Here, we combined the use of ground penetrating radar (GPR) and high-resolution (HR) spotlight TerraSAR-X (TSX) satellite data (1.25 m resolution) to identify and characterize floating ice and grounded ice conditions in lakes, ponds, beaded stream pools, and an alluvial river channel. Classified ice conditions from the GPR and the TSX data showed excellent agreement: 90.6% for a predominantly floating ice lake, 99.7% for a grounded ice lake, 79.0% for a beaded stream course, and 92.1% for the alluvial river channel. A GIS-based analysis of 890 surface water features larger than 0.01 ha showed that 42% of the total surface water area potentially provided over-wintering habitat during the 2012/2013 winter. Lakes accounted for 89% of this area, whereas the alluvial river channel accounted for 10% and ponds and beaded stream pools each accounted for <1%. Identification of smaller landscape features such as beaded stream pools may be important because of their distribution and role in connecting other water bodies on the landscape. These findings advance techniques for detecting and knowledge associated with potential winter habitat distribution for fish and invertebrates at the local scale in a region of the Arctic with increasing stressors related to climate and land use change.

Circulation and water properties in the landfast ice zone of the Alaskan Beaufort Sea

NASA Astrophysics Data System (ADS)

Weingartner, Thomas J.; Danielson, Seth L.; Potter, Rachel A.; Trefry, John H.; Mahoney, Andy; Savoie, Mark; Irvine, Cayman; Sousa, Leandra

2017-09-01

Moorings, hydrography, satellite-tracked drifters, and high-frequency radar data describe the annual cycle in circulation and water properties in the landfast ice zone (LIZ) of the Alaskan Beaufort Sea. Three seasons, whose duration and characteristics are controlled by landfast ice formation and ablation, define the LIZ: ;winter;, ;break-up;, and ;open-water;. Winter begins in October with ice formation and ends in June when rivers commence discharging. Winter LIZ ice velocities are zero, under-ice currents are weak ( 5 cm s-1), and poorly correlated with winds and local sea level. The along-shore momentum balance is between along-shore pressure gradients and bottom and ice-ocean friction. Currents at the landfast ice-edge are swift ( 35 cm s-1), wind-driven, with large horizontal shears, and potentially unstable. Weak cross-shore velocities ( 1 cm s-1) imply limited exchanges between the LIZ and the outer shelf in winter. The month-long break-up season (June) begins with the spring freshet and concludes when landfast ice detaches from the bottom. Cross-shore currents increase, and the LIZ hosts shallow ( 2 m), strongly-stratified, buoyant and sediment-laden, under-ice river plumes that overlie a sharp, 1 m thick, pycnocline across which salinity increases by 30. The plume salt balance is between entrainment and cross-shore advection. Break-up is followed by the 3-month long open-water season when currents are swift (≥20 cm s-1) and predominantly wind-driven. Winter water properties are initialized by fall advection and evolve slowly due to salt rejection from ice. Fall waters and ice within the LIZ derive from local rivers, the Mackenzie and/or Chukchi shelves, and the Arctic basin.

Direct observations of ice seasonality reveal changes in climate over the past 320–570 years

USGS Publications Warehouse

Sharma, Sapna; Magnuson, John J.; Batt, Ryan D.; Winslow, Luke; Korhonen, Johanna; Yasuyuki Aono,

2016-01-01

Lake and river ice seasonality (dates of ice freeze and breakup) responds sensitively to climatic change and variability. We analyzed climate-related changes using direct human observations of ice freeze dates (1443–2014) for Lake Suwa, Japan, and of ice breakup dates (1693–2013) for Torne River, Finland. We found a rich array of changes in ice seasonality of two inland waters from geographically distant regions: namely a shift towards later ice formation for Suwa and earlier spring melt for Torne, increasing frequencies of years with warm extremes, changing inter-annual variability, waning of dominant inter-decadal quasi-periodic dynamics, and stronger correlations of ice seasonality with atmospheric CO2 concentration and air temperature after the start of the Industrial Revolution. Although local factors, including human population growth, land use change, and water management influence Suwa and Torne, the general patterns of ice seasonality are similar for both systems, suggesting that global processes including climate change and variability are driving the long-term changes in ice seasonality.

Direct observations of ice seasonality reveal changes in climate over the past 320–570 years

PubMed Central

Sharma, Sapna; Magnuson, John J.; Batt, Ryan D.; Winslow, Luke A.; Korhonen, Johanna; Aono, Yasuyuki

2016-01-01

Lake and river ice seasonality (dates of ice freeze and breakup) responds sensitively to climatic change and variability. We analyzed climate-related changes using direct human observations of ice freeze dates (1443–2014) for Lake Suwa, Japan, and of ice breakup dates (1693–2013) for Torne River, Finland. We found a rich array of changes in ice seasonality of two inland waters from geographically distant regions: namely a shift towards later ice formation for Suwa and earlier spring melt for Torne, increasing frequencies of years with warm extremes, changing inter-annual variability, waning of dominant inter-decadal quasi-periodic dynamics, and stronger correlations of ice seasonality with atmospheric CO2 concentration and air temperature after the start of the Industrial Revolution. Although local factors, including human population growth, land use change, and water management influence Suwa and Torne, the general patterns of ice seasonality are similar for both systems, suggesting that global processes including climate change and variability are driving the long-term changes in ice seasonality. PMID:27113125

Glacial Lake Musselshell: Late Wisconsin slackwater on the Laurentide ice margin in central Montana, USA

USGS Publications Warehouse

Davis, N.K.; Locke, W. W.; Pierce, K.L.; Finkel, R.C.

2006-01-01

Cosmogenic surface exposure ages of glacial boulders deposited in ice-marginal Lake Musselshell suggest that the lake existed between 20 and 11.5 ka during the Late Wisconsin glacial stage (MIS 2), rather than during the Late Illinoian stage (MIS 6) as traditionally thought. The altitude of the highest ice-rafted boulders and the lowest passes on the modern divide indicate that glacial lake water in the Musselshell River basin reached at least 920-930 m above sea level and generally remained below 940 m. Exposures of rhythmically bedded silt and fine sand indicate that Lake Musselshell is best described as a slackwater system, in which the ice-dammed Missouri and Musselshell Rivers rose and fell progressively throughout the existence of the lake rather than establishing a lake surface with a stable elevation. The absence of varves, deltas and shorelines also implies an unstable lake. The changing volume of the lake implies that the Laurentide ice sheet was not stable at its southernmost position in central Montana. A continuous sequence of alternating slackwater lake sediment and lacustrine sheetflood deposits indicates that at least three advances of the Laurentide ice sheet occurred in central Montana between 20 and 11.5 ka. Between each advance, it appears that Lake Musselshell drained to the north and formed two outlet channels that are now occupied by extremely underfit streams. A third outlet formed when the water in Lake Musselshell fully breached the Larb Hills, resulting in the final drainage of the lake. The channel through the Larb Hills is now occupied by the Missouri River, implying that the present Missouri River channel east of the Musselshell River confluence was not created until the Late Wisconsin, possibly as late as 11.5 ka. ?? 2005 Elsevier B.V. All rights reserved.

The Devdorak ice-rock avalanche and consequent debris flow from the slope of Mt. Kazbek (Caucasus, Georgia) in 2014

NASA Astrophysics Data System (ADS)

Chernomorets, Sergey; Savernyuk, Elena; Petrakov, Dmitry; Dokukin, Mikhail; Gotsiridze, George; Gavardashvili, Givi; Drobyshev, Valery; Tutubalina, Olga; Zaporozhchenko, Eduard; Kamenev, Nikolay; Kamenev, Vladimir; Kääb, Andreas; Kargel, Jeffrey; Huggel, Christian

2016-04-01

We have studied catastrophic glacial events of 2014 in the Kazbek-Dzhimaray massif, Caucasus Mts., Georgia. The first event is a so called "Kazbek blockage" of the Georgian Military Road, on 17 May 2014, which formed as a result of an ice-rock avalanche onto the Devdorak Glacier, and is similar to blockages which occurred in the same location in the 18th-19th century. The second event is a consequent debris flow on 20 August 2014. In May, June 2014 and September 2015 we conducted three field investigations of the disaster zone, which includes Devdorak Glacier, Amilishka and Kabakhi river valleys, the Terek River valley near the Kabakhi River mouth, and a temporary lake.We analyzed field research data, interpreted SPOT 6, Landsat-8 OLI, Terra ASTER, and Pleiades satellite imagery, as well as post-disaster helicopter imagery. To assess dynamic features of the ice-rock flow on 17 May 2014, we measured valley crossections with Bushnell laser ranger. In 2015 we have marked a 180-m baseline for ground stereosurvey and made a stereopair of the Devdorak glacier terminus from a distance of 700 m. The 17 May 2014 ice-rock avalanche initiated at 4500 m. a.s.l. It collapsed onto the tongue of the Devdorak Glacier which reaches down to 2300 m a.s.l. Downstream of the tongue, the avalanche transformed into an ice-rock "avalanche flow" which blocked the Terek River valley. The traffic on Military Georgian Road (part of E117 highway) which connects Russia with Georgia was stopped. 7 people were killed in their vehicles. The total length of the ice-rock avalanche and the subsequent flow was over 10 km. A temporary lake formed in the Terek river valley, reaching 300 m in length, and over 10 m in depth. For several hours, the lake was threatening another debris flow downstream the Terek river valley. According to field estimates at the Devdorak glacier tongue and in Amilishka, Kabakhi and Terek river valleys, the volume of the transported ice-rock avalanche mass, which deposited in the middle and lower course of the valley below 3000 m a.s.l. was about 2 million cubic metres, while the ice content in the deposits reached 25-30%. It is planned to assess the volume of the trigger mass in the initiation zone later. The flow went along the valley with characteristic superelevations and run-ups, as it moved from one valley side to the other. We identified six superelevaions in fresh deposits, with differences of up to 45 m in flow height on the left and right valley banks. Instrumental measurements of superelevations and subsequent calculations yield the flow velocities of over 200 km/hour. These results lead to a reassessment of similar events which occurred in this valley in 18-19th centuries. Previously the trigger of these events was supposed to be the ice accumulation during surges of Devdorak glacier with subsequent temporary damming of the Amilishka River valley. The analysis of the 2014 event demonstrates that a similar trigger was possible in the past: an ice-rock avalanche onto Devdorak glacier tongue from significantly higher locations. Following the field data analysis, we issued a warning through mass media on 12 August 2014, forecasting a high risk of a new glacial disaster in this site and a new blockage of the Terek River valley and of Military Georgian Road. This forecast came true on 20 August 2014: a glacial debris flow reached the Terek River valley, and partially buried the Dariali hydropower station (under construction), the customs and border control buildings. Three people have been killed. We studied the deposits of this debris flow and morphology of the gully. The deposits entrained by the flow were previously deposited by the ice-rock avalanche of 17 May 2014. The debris flow started after shower rains. The debris flow-gully has a box-like crossection. At the confluence of Amilishka and Chach rivers it reached 30-32 m in width, and eroded the deposits of 17 May 2014 by 7 m. The channel slope at this location was about 7 degrees. Remnant ice in the transit zone has nearly melted by September 2015; however, the ice remains in the deposits near the glacier tongue and in the ice-rock avalanche deposits on the tongue. We have registered the advance of one of the termini of Devdorak Glacier. It moved forward by about 200 m from summer 2014 to September 2015, and became significantly higher. This part of the glacier was overloaded by the ice-rock avalanche deposits which provoked its advance, and should be closely monitored as it can raise the debris flow activity further. The hazard of new ice-rock avalanches and debris flows in the Devdorak gorge remains high. We have developed recommendation on the installation of an early warning system, continuation of glacier hazard monitoring, and suggestions on the construction of a road tunnel to mitigate the risk and avoid casualties in the future.

The role of ice dynamics in shaping vegetation in flowing waters.

PubMed

Lind, Lovisa; Nilsson, Christer; Polvi, Lina E; Weber, Christine

2014-11-01

Ice dynamics is an important factor affecting vegetation in high-altitude and high-latitude streams and rivers. During the last few decades, knowledge about ice in streams and rivers has increased significantly and a respectable body of literature is now available. Here we review the literature on how ice dynamics influence riparian and aquatic vegetation. Traditionally, plant ecologists have focused their studies on the summer period, largely ignoring the fact that processes during winter also impact vegetation dynamics. For example, the freeze-up period in early winter may result in extensive formation of underwater ice that can restructure the channel, obstruct flow, and cause flooding and thus formation of more ice. In midwinter, slow-flowing reaches develop a surface-ice cover that accumulates snow, protecting habitats under the ice from formation of underwater ice but also reducing underwater light, thus suppressing photosynthesis. Towards the end of winter, ice breaks up and moves downstream. During this transport, ice floes can jam up and cause floods and major erosion. The magnitudes of the floods and their erosive power mainly depend on the size of the watercourse, also resulting in different degrees of disturbance to the vegetation. Vegetation responds both physically and physiologically to ice dynamics. Physical action involves the erosive force of moving ice and damage caused by ground frost, whereas physiological effects - mostly cell damage - happen as a result of plants freezing into the ice. On a community level, large magnitudes of ice dynamics seem to favour species richness, but can be detrimental for individual plants. Human impacts, such as flow regulation, channelisation, agriculturalisation and water pollution have modified ice dynamics; further changes are expected as a result of current and predicted future climate change. Human impacts and climate change can both favour and disfavour riverine vegetation dynamics. Restoration of streams and rivers may mitigate some effects of anticipated climate change on ice and vegetation dynamics by, for example, slowing down flows and increasing water depth, thus reducing the potential for massive formation of underwater ice. © 2014 The Authors. Biological Reviews © 2014 Cambridge Philosophical Society.

A High-Resolution Model of the Beaufort Sea Circulation

NASA Astrophysics Data System (ADS)

Hedstrom, K.; Danielson, S. L.; Curchitser, E. N.; Lemieux, J. F.; Kasper, J.

2016-02-01

Configuration of and results from a coupled sea-ice ocean model of the Beaufort Sea shelf at 900 m resolution will be shown. Challenging features of the domain include large fresh water flux from the MacKenzie River, seasonal land-fast ice, and ice-covered open boundary conditions. A pan-Arctic domain provides boundary fields for both the ocean and sea-ice models (Regional Ocean Modeling System - myroms.org). Both models are forced with river inputs from the ARDAT climatology (Whitefield et al., 2015), which includes heat content as well as flow rate. Coastal discharges are prescribed as lateral inflows distributed over the depth of the ocean-land interface. New in the Beaufort domain is the use of a landfast ice parameterization (Lemieux, 2015), which adds a large bottom stress to the ice when the estimated keel depth approaches that of the ocean.

Man in the Arctic, The Changing Nature of His Quest for Food and Water as Related to Snow, Ice, and Permafrost

DTIC Science & Technology

1962-01-01

Sub- marines have been used under the ice pack. The most systematic and concerted effort has bet that conducted in Greenland where data from nearly...ml -’ -•- ice individually, chronic thirst was a common complaint. In fact, one cause of dehydration ex- haustion was seen .15 The problem of...made by truck or sledge and bar- rel. For example, at Hay River water is supplied under franchise by a trucker. This water is drawn from the river and

Dissolved organic matter composition of Arctic rivers: Linking permafrost and parent material to riverine carbon

USGS Publications Warehouse

O’Donnell, Jonathan A.; Aiken, George R.; Swanson, David K.; Santosh, Panda; Butler, Kenna D.; Baltensperger, Andrew P.

2016-01-01

Recent climate change in the Arctic is driving permafrost thaw, which has important implications for regional hydrology and global carbon dynamics. Permafrost is an important control on groundwater dynamics and the amount and chemical composition of dissolved organic matter (DOM) transported by high-latitude rivers. The consequences of permafrost thaw for riverine DOM dynamics will likely vary across space and time, due in part to spatial variation in ecosystem properties in Arctic watersheds. Here we examined watershed controls on DOM composition in 69 streams and rivers draining heterogeneous landscapes across a broad region of Arctic Alaska. We characterized DOM using bulk dissolved organic carbon (DOC) concentration, optical properties, and chemical fractionation and classified watersheds based on permafrost characteristics (mapping of parent material and ground ice content, modeling of thermal state) and ecotypes. Parent material and ground ice content significantly affected the amount and composition of DOM. DOC concentrations were higher in watersheds underlain by fine-grained loess compared to watersheds underlain by coarse-grained sand or shallow bedrock. DOC concentration was also higher in rivers draining ice-rich landscapes compared to rivers draining ice-poor landscapes. Similarly, specific ultraviolet absorbance (SUVA254, an index of DOM aromaticity) values were highest in watersheds underlain by fine-grained deposits or ice-rich permafrost. We also observed differences in hydrophobic organic acids, hydrophilic compounds, and DOM fluorescence across watersheds. Both DOC concentration and SUVA254 were negatively correlated with watershed active layer thickness, as determined by high-resolution permafrost modeling. Together, these findings highlight how spatial variations in permafrost physical and thermal properties can influence riverine DOM.

Deglaciation of the northwestern White Mountains, New Hampshire

USGS Publications Warehouse

Thompson, W.B.; Fowler, B.K.; Dorion, C.C.

1999-01-01

The mode of deglaciation in the northwestern White Mountains of New Hampshire has been controversial since the mid 1800's. Early workers believed that active ice deposited the Bethlehem Moraine complex in the Ammonoosuc River basin during recession of the last ice sheet. In the 1930's this deglaciation model was replaced by the concept of widespread simultaneous stagnation and downwastage of Late Wisconsinan ice. The present authors reexamined the Bethlehem Moraine complex and support the original interpretation of a series of moraines deposited by active ice. We found other moraine clusters of similar age to the northeast in the Johns River and Israel River basins. Ice-marginal deposits that probably correlate with the Bethlehem Moraine also occur west of Littleton. The Bethlehem Moraine complex and equivalent deposits in adjacent areas were formed by readvance and oscillatory retreat of the Connecticut Valley lobe of the Laurentide Ice Sheet. This event is called the Littleton-Bethlehem Readvance. Throughout the study area, sequences of glaciolacustrine deposits and meltwater drainage channels indicate progressive northward recession of the glacier margin. Radiocarbon dates from nearby New England and Quebec suggest that the ice sheet withdrew from this part of the White Mountains between about 12,500 and 12,000 14C yr BP. We attribute the Littleton-Bethlehem Readvance to a brief climatic cooling during Older Dyas time, close to 12,000 BP.

Studies of the inner shelf and coastal sedimentation environment of the Beaufort Sea from ERTS-A

NASA Technical Reports Server (NTRS)

Reimnitz, E. (Principal Investigator); Barnes, P. W.; Toimil, L. J.; Harden, D.

1976-01-01

The author has identified the following significant results. Shearing periodically occurs between the westward moving pack ice (3 to 10 km/d) within the Pacific Gyre and the fast ice along the coast, forming major grounded shear and pressure ridges between the 10 to 40 m isobaths. Ridges occur in patterns conforming to known shoals. The zone of grounded ridges, called stamukhi zone, protects the inner shelf and coast from marine energy and pack ice forces. Relatively undeformed fast ice grows inshore of the stamukhi zone. The boundary is explained in terms of pack ice drift and major promontories and shoals. Intense ice gaging, highly disrupted sediments, and landward migration of shoals suggest that much of the available marine energy is expended on the sea floor within the stamukhi zone. Naleds (products of river icings) on the North Slope are more abundant east than west of the Colville River. Their location, growth, and decay were studied from LANDSAT imagery.

Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet.

PubMed

Smith, Laurence C; Chu, Vena W; Yang, Kang; Gleason, Colin J; Pitcher, Lincoln H; Rennermalm, Asa K; Legleiter, Carl J; Behar, Alberto E; Overstreet, Brandon T; Moustafa, Samiah E; Tedesco, Marco; Forster, Richard R; LeWinter, Adam L; Finnegan, David C; Sheng, Yongwei; Balog, James

2015-01-27

Thermally incised meltwater channels that flow each summer across melt-prone surfaces of the Greenland ice sheet have received little direct study. We use high-resolution WorldView-1/2 satellite mapping and in situ measurements to characterize supraglacial water storage, drainage pattern, and discharge across 6,812 km(2) of southwest Greenland in July 2012, after a record melt event. Efficient surface drainage was routed through 523 high-order stream/river channel networks, all of which terminated in moulins before reaching the ice edge. Low surface water storage (3.6 ± 0.9 cm), negligible impoundment by supraglacial lakes or topographic depressions, and high discharge to moulins (2.54-2.81 cm⋅d(-1)) indicate that the surface drainage system conveyed its own storage volume every <2 d to the bed. Moulin discharges mapped inside ∼52% of the source ice watershed for Isortoq, a major proglacial river, totaled ∼41-98% of observed proglacial discharge, highlighting the importance of supraglacial river drainage to true outflow from the ice edge. However, Isortoq discharges tended lower than runoff simulations from the Modèle Atmosphérique Régional (MAR) regional climate model (0.056-0.112 km(3)⋅d(-1) vs. ∼0.103 km(3)⋅d(-1)), and when integrated over the melt season, totaled just 37-75% of MAR, suggesting nontrivial subglacial water storage even in this melt-prone region of the ice sheet. We conclude that (i) the interior surface of the ice sheet can be efficiently drained under optimal conditions, (ii) that digital elevation models alone cannot fully describe supraglacial drainage and its connection to subglacial systems, and (iii) that predicting outflow from climate models alone, without recognition of subglacial processes, may overestimate true meltwater export from the ice sheet to the ocean.

Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet

PubMed Central

Smith, Laurence C.; Chu, Vena W.; Yang, Kang; Gleason, Colin J.; Pitcher, Lincoln H.; Rennermalm, Asa K.; Legleiter, Carl J.; Behar, Alberto E.; Overstreet, Brandon T.; Moustafa, Samiah E.; Tedesco, Marco; Forster, Richard R.; LeWinter, Adam L.; Finnegan, David C.; Sheng, Yongwei; Balog, James

2015-01-01

Thermally incised meltwater channels that flow each summer across melt-prone surfaces of the Greenland ice sheet have received little direct study. We use high-resolution WorldView-1/2 satellite mapping and in situ measurements to characterize supraglacial water storage, drainage pattern, and discharge across 6,812 km2 of southwest Greenland in July 2012, after a record melt event. Efficient surface drainage was routed through 523 high-order stream/river channel networks, all of which terminated in moulins before reaching the ice edge. Low surface water storage (3.6 ± 0.9 cm), negligible impoundment by supraglacial lakes or topographic depressions, and high discharge to moulins (2.54–2.81 cm⋅d−1) indicate that the surface drainage system conveyed its own storage volume every <2 d to the bed. Moulin discharges mapped inside ∼52% of the source ice watershed for Isortoq, a major proglacial river, totaled ∼41–98% of observed proglacial discharge, highlighting the importance of supraglacial river drainage to true outflow from the ice edge. However, Isortoq discharges tended lower than runoff simulations from the Modèle Atmosphérique Régional (MAR) regional climate model (0.056–0.112 km3⋅d−1 vs. ∼0.103 km3⋅d−1), and when integrated over the melt season, totaled just 37–75% of MAR, suggesting nontrivial subglacial water storage even in this melt-prone region of the ice sheet. We conclude that (i) the interior surface of the ice sheet can be efficiently drained under optimal conditions, (ii) that digital elevation models alone cannot fully describe supraglacial drainage and its connection to subglacial systems, and (iii) that predicting outflow from climate models alone, without recognition of subglacial processes, may overestimate true meltwater export from the ice sheet to the ocean. PMID:25583477

Impacts des conditions de glace de mer sur la reproduction des eiders a duvet (Somateria mollissima) nichant dans l'Arctique canadien

NASA Astrophysics Data System (ADS)

Jean-Gagnon, Frankie

Environmental and climatic conditions on the breeding site affect the reproduction and dynamics of avian populations. The arctic sea ice is an essential environmental component to many marine species, and the sea ice dynamic can affect seabird reproduction. Our objective was to study the role of sea ice conditions early in the season on breeding decisions of Common eiders nesting at East Bay in the Canadian Arctic. Since eider females forage intensively at river mouths at East Bay during the pre-breeding period, we made the assumption that the timing of ice-breakup at river mouths influences the breeding propensity and the timing of laying through an effect on resources accessibility. Using radar satellite images acquired for the summers 2002 to 2013, we determined the timing of ice-breakup at river mouths and the ice-free conditions in the bay for each year. The timing of ice-breakup in June varied greatly between years and was strongly correlated to the day of ice-free conditions in the bay in July. Our results also demonstrated that a late ice-breakup induces a decrease in breeding propensity and a delay in the laying date in common eiders. However, females in lower body condition were more strongly affected by a late ice-breakup than females in better condition. These results shed light on the critical importance of the timing of resources accessibility for reproductive decisions and success of avian species breeding in the Arctic. Furthermore, the timing of ice-breakup could be used as an environmental cue by eiders to adjust their timing of breeding. Globally, our study allows us to better understand the mechanisms underlying the effects of sea ice conditions on breeding decisions of marine birds. This work could be useful to anticipate the effect of climate change on population dynamics of birds breeding in the Arctic.

An integrated approach to the remote sensing of floating ice

NASA Technical Reports Server (NTRS)

Campbell, W. J.; Ramseier, R. O.; Weeks, W. F.; Gloersen, P.

1976-01-01

Review article on remote sensing applications to glaciology. Ice parameters sensed include: ice cover vs open water, ice thickness, distribution and morphology of ice formations, vertical resolution of ice thickness, ice salinity (percolation and drainage of brine; flushing of ice body with fresh water), first-year ice and multiyear ice, ice growth rate and surface heat flux, divergence of ice packs, snow cover masking ice, behavior of ice shelves, icebergs, lake ice and river ice; time changes. Sensing techniques discussed include: satellite photographic surveys, thermal IR, passive and active microwave studies, microwave radiometry, microwave scatterometry, side-looking radar, and synthetic aperture radar. Remote sensing of large aquatic mammals and operational ice forecasting are also discussed.

Effects of Ship-Induced Waves in an Ice Environment on the St. Marys River Ecosystem,

DTIC Science & Technology

1980-01-01

Oligochaeta (worms), and Gastropoda (snails) comprised about 67% of the total number of organisms collected. Pelecypoda (fingernail clams), Amphipoda...Identiflero/Open.Endad Terms St. Marys River, winter navigation, Chronomidae, Oligochaetes, Gastropoda , ice c. cosATI ieid/Group IS. Availaleity...Chronomidae (midge larvae), Oligochaeta (worms), and Gastropoda (snails); collectively they comprised about 67% of the total number of organisms

Quaternary geologic map of the Shelby 1° x 2° quadrangle, Montana

USGS Publications Warehouse

Fullerton, David S.; Colton, Roger B.; Bush, Charles A.

2013-01-01

The Shelby quadrangle encompasses approximately 16,084 km2 (6,210 mi2). The northern boundary is the Montana/Saskatchewan (U.S./Canada) boundary. The quadrangle is in the Northern Plains physiographic province and it includes the Sweet Grass Hills. The primary river is the Marias River. The ancestral Missouri River was diverted south of the Bearpaw Mountains by a Laurentide ice sheet. The fill in the buried ancestral valleys of the Missouri River and Marias River in the southeast quarter of the quadrangle contains a complex stratigraphy of fluvial, glaciofluvial, ice-contact, glacial, lacustrine, and eolian deposits. The map units are surficial deposits and materials, not landforms. Deposits that comprise some constructional landforms (for example, ground-moraine deposits, end-moraine deposits, stagnation-moraine deposits, all composed of till) are distinguished for purposes of reconstruction of glacial history. Surficial deposits and materials are assigned to 21 map units on the basis of genesis, age, lithology or composition, texture or particle size, and other physical, chemical, and engineering characteristics. It is not a map of soils that are recognized in pedology or agronomy. Rather, it is a generalized map of soils recognized in engineering geology, or of substrata or parent materials in which pedologic or agronomic soils are formed. Glaciotectonic (ice-thrust) structures and deposits are mapped separately, represented by a symbol. On the glaciated plains, the surficial deposits are glacial, ice-contact, glaciofluvial, alluvial, lacustrine, eolian, colluvial, and mass-movement deposits. In the Sweet Grass Hills, beyond the limit of Quaternary glaciation they are fluvial, colluvial, and mass-movement deposits. Till of late Wisconsin age is represented by three map units. Tills of Illinoian and pre-Illinoian glaciations are not mapped, but are widespread in the subsurface. Linear ice-molded landforms (primarily drumlins) indicate directions of ice flow during late Wisconsin glaciation.

Forecast Tools for Alaska River Ice Breakup Timing and Severity

NASA Astrophysics Data System (ADS)

Moran, E. H.; Lindsey, S.; van Breukelen, C. M.; Thoman, R.

2016-12-01

Spring Breakup on the large interior rivers in Alaska means a time of nervous anticipation for many of the residents in the villages alongside those rivers. On the Yukon and Kuskokwim Rivers the record flood for most villages occurred as a result of ice jams that backed up water and dump truck sized ice floes into the village. Those floods can occur suddenly and can literally wipe out a village. The challenge is that with a limited observation network (3 automated USGS gages along the 1200 miles of the Yukon River flowing through Alaska) and the inherently transient nature of ice jam formation, prediction of the timing and severity of these events has been a tremendous challenge. Staff at the Alaska Pacific River Forecast Center as well as the Alaska Region Climate Program Manager have been developing more quantitative tools to attempt to provide a longer lead time for villages to prepare for potentially devastating flooding. In the past, a very qualitative assessment of the primary drivers of Spring Breakup (snow pack, river ice thickness and forecast spring weather) have led to the successful identification of years when flood severity was likely to be elevated or significantly decreased. These qualitative assessments have also allowed the forecasting of the probability of either a thermal or a dynamic breakup. But there has continued to be a need for an objective tool that can handle weather patterns that border on the tails of the climatic distributions as well as the timing and flood potential from weather patterns that are closer to the median of the distribution. Over the past 8 years there have been a significant number of years with anomalous spring weather patterns including cold springs followed by rapid warmups leading to record flooding from ice jams during spring breakup (2009, 2013), record late breakup (2013), record early breakup (2016), record high snowfall (2012), record snowmelt and aufeis flooding (2015) and record low snowfall (2015). The need for improved tools that can handle these events over the full breadth of the distribution has never been greater. This talk will describe efforts to incorporate climate signals into the spring breakup outlook and show results of some temperature based indices as an indicator of breakup timing.

The mosaic accessory gene structures of the SXT/R391-like integrative and conjugative elements derived from Vibrio spp. isolated from aquatic products and environment in the Yangtze River estuary, China

PubMed Central

2013-01-01

Background The emergence, resurgence and spread of human food-borne pathogenic Vibrios are one of the major contributors to disease burden and mortality particularly in developing countries with disputable sanitary conditions. Previous research on pathogenic Vibrio cholerae and Vibrio parahaemolitycus derived from clinical samples has proposed links between acquisition of virulence and multiple drug resistance traits and intercellular transmissibility of mobile genetic elements in the environment. To date, very few information is available on environmental Vibrio isolates. In this study, we characterized eleven Vibrio strains bearing the SXT/R391-like integrative and conjugative elements (ICEs) derived from aquatic products and environment in the Yangtze River Estuary, China. Results The eleven Vibrio strains were isolated in 2010 to 2011, and taxonomically identified, which included six Vibrio cholerae, three Vibrio parahaemolyticus, one Vibrio alginolyticus and one Vibrio natriegens. Most of the strains displayed strong resistance phenotypes to ampicillin, mercury and chromium. The majority of their ICEs, which belong to S and R exclusion system groups, contain ICEs-chromosome junction sequences and highly conserved core-genes required for ICE transfer. However, comparative sequence analysis uncovered interesting diversity in their mosaic accessory gene structures, which carry many novel genes that have not been described in any known ICEs to date. In addition, antibiotic resistance was transmitted by ICEVchChn6 and ICEVpaChn1 from V. cholerae, V. parahaemolyticus to E. coli MG1655 via conjugation, respectively. Our data also revealed that the ICEs characterized in this study are phylogenetically distant from most of the SXT/R391 ICEs reported previously, which may represent a novel cluster likely shaped by the ecological environment in the Yangtze River Estuary, China. Conclusions This study constitutes the first investigation of ICEs-positive Vibrio spp. in the Yangze River Estuary, China. The newly identified ICEs were characterized with mosaic accessory gene structures and many novel genes. The results demonstrated self-transmissibility of antibiotic resistance mediated by two of the ICEs from V. cholerae, V. parahaemolyticus to E. coli via conjugation, respectively. Our results also revealed that the ICEs examined in this study may represent a novel cluster in the SXT/R391 family. PMID:24074349

Ice detection systems : experimental feature : final report.

DOT National Transportation Integrated Search

1986-01-01

In the fall of 1980, an experimental ice detection system was installed on the Fremont Bridge in Portland, Oregon. this bridge, which caries I-405 over the Willamette River, has a history of icing problem when the deck is wet and the temperature hove...

Geophysical investigation and monitoring of thermo-hydraulic conditions of closed talik and icing of the Kuuguluk River at Salluit, northern Quebec, Canada

NASA Astrophysics Data System (ADS)

Fortier, R.; Lemieux, J. M.; Molson, J. W. H.; Therrien, R.; Ouellet, M.

2016-12-01

The Inuit community of Salluit in northern Quebec, Canada, is located in the continuous permafrost zone characterized by a mean annual air temperature (MAAT) of -8.0 °C over the period from 1981 to 2010. In such cold environment, it is challenging to find a sustainable supply of water. A well drilled in fractured bedrock and located in a closed talik underneath the Kuuguluk River is used as a source of drinking water by the municipality of Salluit. To verify the lateral extent of the closed talik beneath the floodplain of Kuuguluk River, a geophysical investigation using ground penetrating radar (GPR) profiling and capacitively-coupled electrical resistivity tomography (ERT) was undertaken in spring 2011. Moreover, a mooring with water level and temperature dataloggers in the river was installed over the 2015-2016 period to assess the thermo-hydraulic conditions of the river bed. The icing which forms each year in the floodplain of Kuuguluk River was used in spring 2011 as a bridge to cross over the river and move along the geophysical equipment. Three thaw bulbs in the ice-rich permafrost of the floodplain were inferred from low resistivity anomalies in the model of electrical resistivity. The largest bulb is about 40 m wide and 14 m thick. According to the mooring results, the mean annual temperature of the river bed (MATRB) was 1.4 °C in 2015-2016 while the MAAT was -7.1 °C. This MATRB above 0 °C is due to the heat storage of running surface water in the river bed and the suprapermafrost water flow in the closed talik. River bed temperature below 0 °C and as low as -3 °C from October 10th 2015 to November 20th 2015 and from January 23rd to April 17th 2016 were recorded. The spring freshet occurred on June 24th2016. Outside these periods, the river bed temperature stayed remarkably stable at 0.05 °C in winter time. While the water level in the Kuuguluk River varies from 0.4 to 1.0 m in summer time following the precipitation events, the water pressure can be as high as 2.8 m in winter under the icing. Sharp water level decrease events of few decimeters due to water pressure release through icing fracturing were also recorded. As a positive impact of the anticipated climate warming over the next decades, the close talik beneath the Kuuguluk River should enlarge enhancing the groundwater availability as a source of drinking water.

Post-glacial variability of sea ice cover, river run-off and biological production in the western Laptev Sea (Arctic Ocean) - A high-resolution biomarker study

NASA Astrophysics Data System (ADS)

Hörner, T.; Stein, R.; Fahl, K.; Birgel, D.

2016-07-01

Multi-proxy biomarker measurements were applied on two sediment cores (PS51/154, PS51/159) to reconstruct sea ice cover (IP25), biological production (brassicasterol, dinosterol) and river run-off (campesterol, β-sitosterol) in the western Laptev Sea over the last ∼17 ka with unprecedented temporal resolution. The absence of IP25 from 17.2 to 15.5 ka, in combination with minimum concentration of phytoplankton biomarkers, suggests that the western Laptev Sea shelf was mostly covered with permanent sea ice. Very minor river run-off and restricted biological production occurred during this cold interval. From ∼16 ka until 7.5 ka, a long-term decrease of terrigenous (riverine) organic matter and a coeval increase of marine organic matter reflect the gradual establishment of fully marine conditions in the western Laptev Sea, caused by the onset of the post-glacial transgression. Intensified river run-off and reduced sea ice cover characterized the time interval between 15.2 and 12.9 ka, including the Bølling/Allerød warm period (14.7-12.9 ka). Prominent peaks of the DIP25 Index coinciding with maximum abundances of subpolar foraminifers, are interpreted as pulses of Atlantic water inflow on the western Laptev Sea shelf. After the warm period, a sudden return to severe sea ice conditions with strongest ice-coverage between 11.9 and 11 ka coincided with the Younger Dryas (12.9-11.6 ka). At the onset of the Younger Dryas, a distinct alteration of the ecosystem (reflected in a distinct drop in terrigenous and phytoplankton biomarkers) was detected. During the last 7 ka, the sea ice proxies reflect a cooling of the Laptev Sea spring/summer season. This cooling trend was superimposed by a short-term variability in sea ice coverage, probably representing Bond cycles (1500 ± 500 ka) that are related to solar activity changes. Hence, atmospheric circulation changes were apparently able to affect the sea ice conditions on the Laptev Sea shelf under modern sea level conditions.

A High-Resolution Model of the Beaufort Sea Circulation

NASA Astrophysics Data System (ADS)

Hedstrom, K.; Danielson, S. L.; Curchitser, E. N.; Lemieux, J. F.; Kasper, J.

2016-12-01

Configuration of and results from a coupled sea-ice ocean model of the Beaufort Sea shelf at 500 m resolution will be shown. Challenging features of the domain include large fresh water flux from the MacKenzie River, seasonal land-fast ice, and ice-covered open boundary conditions. A pan-Arctic domain provides boundary fields to an intermediate resolution (4 km) domain which in turn provides boundary fields to the Beaufort Shelf domain. These are all coupled ocean and sea-ice models (Regional Ocean Modeling System - myroms.org) and all are forced with river inputs from the ARDAT climatology (Whitefield et al., 2015), which includes heat content as well as flow rate. Coastal discharges are prescribed as lateral inflows distributed over the depth of the ocean-land interface. New in the Beaufort domain is the use of a landfast ice parameterization (Lemieux, 2015), which adds a large bottom stress to the ice when the estimated keel depth approaches that of the ocean.

Sea ice around Ostrov Sakhalin, eastern Russia

NASA Image and Video Library

2017-12-08

Located off the east coast of Russia, the Sea of Okhotsk stretches down to 45 degrees North latitude, and sea ice forms regularly in the basin. In fact, it is the lowest latitude for seasonal sea ice formation in the world. On January 4, 2015, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this true-color image of the ice-covered Sea of Okhotsk. Every winter, winds from East Siberia, frigid air temperatures, and a large amount of freshwater flowing out from rivers promote the formation of sea ice in the region. Much of the freshwater comes from the Amur River, one of the ten longest rivers in the world. From year to year, variations in temperature and wind speed can cause large fluctuations in sea ice extent. The sea spans more than 1,500,000 square kilometers (600,000 square miles), and ice cover can spread across 50 to 90 percent of it at its annual peak. On average, that ice persists for 180 days. According to research published in 2014, the region's sea ice has been decreasing over a 34-year period. Annual ice production in the Sea of Okhotsk dropped by more than 11 percent from 1974 to 2008. The researchers suggest that this decline has, at least in part, "led to weakening of the overturning in the North Pacific." Water with less sea ice is fresher, less dense, and unable to sink and circulate as well as salty, dense water. A weakened circulation in the North Pacific has implications for the supply of nutrients, such as iron, that affect biological productivity. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Annual glacier dammed lake drainage in Zackenberg, Northeast Greenland

NASA Astrophysics Data System (ADS)

Lane, Timothy; Adamson, Kathryn; Matthews, Tom

2016-04-01

A.P. Olsen is a 295 km2 ice cap in the Zackenberg region of Northeast Greenland (74.6° N, 21.5° W), 35 km from the ZERO Zackenberg Research Station. The ice cap lies on a gneissic plateau, covering an elevation of 200 to 1450 m a.s.l. A.P. Olsen mass balance has been monitored since 2008 and reconstructed for the period 1995-2007. Meltwater from this ice cap drains into the Zackenberg River, and into Young Sund via the Zackenberg Delta. One outlet dams a c. 0.8 km2 lake fed by the northern part of the ice cap. Observational data suggests this lake drains annually, flooding subglacially into the Zackenberg River. But the impacts of these flood events on the hydrology, sediment transfer, and geomorphology of the proglacial zone downstream have not been examined in detail. Understanding the impacts of glacial lake outburst flood events is important in the sensitive Arctic environment, where glacial change is rapid. We use Landsat scenes to reconstruct lake extent from 1999-2015. This is compared to Zackenberg River discharge measurements, available from the ZERO Zackenberg monitoring programme. These datasets are used to examine the nature and timing of flood events, and assess the impacts on the Zackenberg river downstream.

Moulin Migration and Development on the Greenland Ice Sheet

NASA Astrophysics Data System (ADS)

Chu, V. W.; Yang, L.

2017-12-01

Extensive river networks that terminate into moulins efficiently drain the surface of the Greenland ice sheet. These river moulins connect surface meltwater to englacial and subglacial drainage networks, where increased meltwater can enhance ice sliding dynamics. Previous moulin studies were limited to small geographic areas using field observations and/or high-resolution aerial/satellite imagery, or to medium-resolution satellite imagery for larger areas. In this study, high-resolution moulin maps created from WorldView-1/2/3 imagery near Russell Glacier in southwest Greenland show development of moulins and their migration between 2012 and 2015. Moulins are mapped and categorized as being located: in crevasse fields, along a single ice fracture, within drained lake basins, or having no visible formation mechanism. A majority of moulins mapped in 2015 (73%) are linked to moulins in 2012 and are analysed for their movement patterns and compared to ice velocity and strain rates. New moulins most commonly form in crevassed, thinner ice near the ice sheet edge, but significant quantities also develop at higher elevations (22% above 1300 m elevation).

Earth observations taken during the STS-59 mission

NASA Image and Video Library

1994-04-16

STS059-90-098 (9-20 April 1994) --- Ice-covered Lake Baikal, in Siberia, is about 400 miles long within a major rift valley. The water surface is 455 meters above sea level, but the bottom is 1,295 meters below sea level; the lake represents the largest body of fresh water in the world, except for the Antarctic and Greenland ice sheets. A tributary, the Senusi River, has built a delta on the east side. The Angara River exits the lake to the northwest; the city of Irkutsk is under the small, rippled cloud bank that crosses the river. Hasselblad camera.

Processes Leading to Beaded Channels Formation in Central Yakutia

NASA Astrophysics Data System (ADS)

Tarbeeva, A. M.; Lebedeva, L.; Efremov, V. S.; Krylenko, I. V.; Surkov, V. V.

2017-12-01

Beaded channels, consisting of deepened and widened pools and connecting narrow runs, are common fluvial forms in permafrost regions. Recent studies have shown that beaded channels are very important for connecting alluvial rivers with headwater lakes allowing fish passage and foraging habitats, as well as regulating river runoff. Beaded channels are known as typical thermokarst landforms; however, there is no evidence of their origin and formative processes. Geomorphological analyzes of beaded channels have been completed in several permafrost regions including field observations of Shestakovka River in Central Yakutia. The study aims to recognize the modern exogenic processes and formative mechanisms of beaded river channels. We show that beaded channel of Shestakovka River form in the perennially frozen sand with low ice content, leading us to hypothesize that thermokarst is not the main process of formation. Due to the significant volume of water, the pools don't freeze over entirely during winters, even under harsh climatic conditions. As a result, lenses of pressurized water remain under surface ice underlain by perennially thawed sediments. The presence of thawed sediments under the pools and frozen sediments under the runs leads to uneven thermoerosion of the riverbed during floods, providing the beaded form of the channel. In addition, freezing of pools during winter leads to pressure increasing under ice cover and formation of ice mounds, which crack several times during winter leading to disturbance of riverbanks. Many 1st to 3rd order streams have a specific transitional meandering-to-beaded form resembling the shape of unconfined meandering rivers, but consisting of pools and runs. However, such channels exhibit no evidences of present-day erosion of concave banks and sediment accumulation at the convex banks as typically being observed in normally meandering rivers. Such forms of channels indicates that their formation occurred by the greater channel-forming flow discharges in the past. Transition to the beaded channel planform took place only later, presumably as a result of climate changes. Reduction of water runoff and freezing over of taliks leaded to activation of cryogenic processes (thermokarst, uneven thermoerosion, disturbance of riverbanks during the cracking of ice mounds).

Remote sensing of snow and ice: A review of the research in the United States 1975 - 1978

NASA Technical Reports Server (NTRS)

Rango, A.

1979-01-01

Research work in the United States from 1975-1978 in the field of remote sensing of snow and ice is reviewed. Topics covered include snowcover mapping, snowmelt runoff forecasting, demonstration projects, snow water equivalent and free water content determination, glaciers, river and lake ice, and sea ice. A bibliography of 200 references is included.

Transport of contaminants by Arctic sea ice and surface ocean currents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pfirman, S.

1995-12-31

Sea ice and ocean currents transport contaminants in the Arctic from source areas on the shelves, to biologically active regions often more than a thousand kilometers away. Coastal regions along the Siberian margin are polluted by discharges of agricultural, industrial and military wastes in river runoff, from atmospheric deposition and ocean dumping. The Kara Sea is of particular concern because of deliberate dumping of radioactive waste, as well as the large input of polluted river water. Contaminants are incorporated in ice during suspension freezing on the shelves, and by atmospheric deposition during drift. Ice releases its contaminant load through brinemore » drainage, surface runoff of snow and meltwater, and when the floe disintegrates. The marginal ice zone, a region of intense biological activity, may also be the site of major contaminant release. Potentially contaminated ice from the Kara Sea is likely to influence the marginal ice zones of the Barents and Greenland seas. From studies conducted to date it appears that sea ice from the Kara Sea does not typically enter the Beaufort Gyre, and thus is unlikely to affect the northern Canadian and Alaskan margins.« less

An Automated Approach to Extracting River Bank Locations from Aerial Imagery Using Image Texture

DTIC Science & Technology

2013-01-01

Atchafalaya River, LA. Map Data: Google, United States Department of Agriculture Farm Ser- vice Agency, Europa Technologies AUTOMATED RIVER BANK...traverse morphologically smooth landscapes including rivers in sand or ice . Within these limitations, we hold that this technique rep- resents a valuable

STS-42 Earth observation of the Rhone River / Lake Geneva in Switzerland

NASA Technical Reports Server (NTRS)

1992-01-01

STS-42 Earth observation taken aboard Discovery, Orbiter Vehicle (OV) 103, shows the Rhone River flowing into Lake Geneva in western Switzerland (46.0N, 7.0E). The sharp change in the valley's orientation is a feature of this view. Several times during cold periods of the Earth's history (the geologically recent Ice Ages of the last 1.5 million years or so), this valley has been filled with ice flowing off the mountain ranges. Ice erosion has widened and lowered the valley. The surrounding mountain chains include the highest peak in Europe, Mont Blanc (15,781 feet) on the French-Italian border, and the well-known Matterhorn (14,130) feet on the Swiss-Italian border. Ice-sculpting has generated the characteristically sharp ridges and pointed peaks of the Alps.

Sea ice cover variability and river run-off in the western Laptev Sea (Arctic Ocean) since the last 18 ka

NASA Astrophysics Data System (ADS)

Hörner, T.; Stein, R.; Fahl, K.; Birgel, D.

2015-12-01

Multi-proxy biomarker measurements were performed on two sediment cores (PS51/154, PS51/159) with the objective reconstructing sea ice cover (IP25, brassicasterol, dinosterol) and river-runoff (campesterol, β-sitosterol) in the western Laptev Sea over the last 18 ka with unprecedented temporal resolution. The sea ice cover varies distinctly during the whole time period. The absence of IP25 during 18 and 16 ka indicate that the western Laptev Sea was mostly covered with permanent sea ice (pack ice). However, a period of temporary break-up of the permanent ice coverage occurred at c. 17.2 ka (presence of IP25). Very little river-runoff occurred during this interval. Decreasing terrigenous (riverine) input and synchronous increase of marine produced organic matter around 16 ka until 7.5 ka indicate the gradual establishment of a marine environment in the western Laptev Sea related to the onset of the post-glacial transgression of the shelf. Strong river run-off and reduced sea ice cover characterized the time interval between 15.2 and 12.9 ka, including the Bølling/Allerød warm period (14.7 - 12.9 ka). Moreover, the DIP25 Index (ratio of HBI-dienes and IP25) might document the presence of Atlantic derived water at the western Laptev Sea shelf area. A sudden return to severe sea ice conditions occurred during the Younger Dryas (12.9 - 11.6 ka). This abrupt climate change was observed in the whole circum-Arctic realm (Chukchi Sea, Bering Sea, Fram Strait and Laptev Sea). At the onset of the Younger Dryas, a distinct alteration of the ecosystem (deep drop in terrigenous and phytoplankton biomarkers) may document the entry of a giant freshwater plume, possibly relating to the Lake Agassiz outburst at 13 ka. IP25 concentrations increase and higher values of the PIP25 Index during the last 7 ka reflect a cooling of the Laptev Sea spring season. Moreover, a short-term variability of c. 1.5 thousand years occurred during the last 12 ka, most probably following Bond Cycles.

Climatic and morphological controls on post-glacial lake and river valley evolution in the Weichselian belt - an example from the Wda valley, Northern Poland

NASA Astrophysics Data System (ADS)

Kramkowski, M. A.; Błaszkiewicz, M.; Piotrowski, J. A.; Brauer, A.; Gierszewski, P.; Kordowski, J.; Lamparski, P.; Lorenz, S.; Noryśkiewicz, A. M.; Ott, F.; Slowinski, M. M.; Tyszkowski, S.

2014-12-01

The River Wda valley is a classical example of a polygenetic valley, consisting of former lake basins joined by erosive gap sections. In its middle section, which was the subject of our research, a fragment of an abandoned Lateglacial river valley is preserved, which is unique for the Weichselian moraine belt in the Central European Lowlands. The analysis of the relationship between the lacustrine and fluvial sediments and landforms enabled the authors to report many evolutionary connections between the initial period of the river system formation and the emergence of lakes during the Weichselian Lateglacial. The surface drainage essentially determined the progress of melting of dead ice blocks buried in the glacial depressions, which finally led to lake formation there. Most of the lake basins in the study area were formed during the Bølling-Allerød period. However, one section of the subglacial channel was not exposed to the thermokarst conditions and was therefore preserved with dead ice blocks throughout the entire Lateglacial. The dead ice decay at the beginning of the Holocene, as well as the emergence of another lake, created a lower base level of erosion in the close vicinity of the abandoned valley and induced a change of the river's course. Both fluvial and lacustrine deposits and landforms distributed in the central section of the River Wda valley indicate two processes, which proceeded simultaneously: (1) emergence of fluvially joined lake basins within a glacial channel, (2) degradation of the river bed in the gap sections interfering between the lakes. The processes described for the central section of the River Wda channel indicate a very dynamic river valley development during the Weichselian Lateglacial and the early Holocene. The valley formation was tightly interwoven with the morphogenesis of the primary basins within the valley, mainly with the melting of the buried blocks of dead ice and the development of lakes. This study is a contribution to the Virtual Institute of Integrated Climate and Landscape Evolution (ICLEA) of the Helmholtz Association and the research project no. 2011/01/B/ST10/07367 Polish Ministry of Science and Higher Education.

Isotopic investigation of rivers runoff in glaciated regions of the central Asian arid highlands (southeastern Altai)

NASA Astrophysics Data System (ADS)

Bantcev, Dmitrii; Ganushkin, Dmitriy; Ekaykin, Alexey; Chistyakov, Kirill

2017-04-01

Stable isotopes investigations were carried out during fieldwork in glacier basins of the Mongun-Taiga (southwestern Tuva) and Tsambagarav (northwestern Mongolia) mountain massifs in July, 2016. These Arid highlands are problematic in the context of provision of water resources, and glaciers here play a large part in nourishment of the rivers. Concentrations of the oxygen 18, deuterium and the mineralization were measured in the samples of meltwater, precipitation, water from streams, ice and snow. Sable isotope method was used for separation of the glacier runoff. Average isotopic characteristics for different water sources, such as glacier ice, snow patches and precipitation, were calculated and the contribution of these sources in total runoff was valued. Isotopic method was also used for estimation of contribution of buried ice meltwater from rock glaciers ice cores.

Uncertainty analysis of the simulations of effects of discharging treated wastewater to the Red River of the North at Fargo, North Dakota, and Moorhead, Minnesota

USGS Publications Warehouse

Wesolowski, Edwin A.

1996-01-01

Two separate studies to simulate the effects of discharging treated wastewater to the Red River of the North at Fargo, North Dakota, and Moorhead, Minnesota, have been completed. In the first study, the Red River at Fargo Water-Quality Model was calibrated and verified for icefree conditions. In the second study, the Red River at Fargo Ice-Cover Water-Quality Model was verified for ice-cover conditions.To better understand and apply the Red River at Fargo Water-Quality Model and the Red River at Fargo Ice-Cover Water-Quality Model, the uncertainty associated with simulated constituent concentrations and property values was analyzed and quantified using the Enhanced Stream Water Quality Model-Uncertainty Analysis. The Monte Carlo simulation and first-order error analysis methods were used to analyze the uncertainty in simulated values for six constituents and properties at sites 5, 10, and 14 (upstream to downstream order). The constituents and properties analyzed for uncertainty are specific conductance, total organic nitrogen (reported as nitrogen), total ammonia (reported as nitrogen), total nitrite plus nitrate (reported as nitrogen), 5-day carbonaceous biochemical oxygen demand for ice-cover conditions and ultimate carbonaceous biochemical oxygen demand for ice-free conditions, and dissolved oxygen. Results are given in detail for both the ice-cover and ice-free conditions for specific conductance, total ammonia, and dissolved oxygen.The sensitivity and uncertainty of the simulated constituent concentrations and property values to input variables differ substantially between ice-cover and ice-free conditions. During ice-cover conditions, simulated specific-conductance values are most sensitive to the headwatersource specific-conductance values upstream of site 10 and the point-source specific-conductance values downstream of site 10. These headwater-source and point-source specific-conductance values also are the key sources of uncertainty. Simulated total ammonia concentrations are most sensitive to the point-source total ammonia concentrations at all three sites. Other input variables that contribute substantially to the variability of simulated total ammonia concentrations are the headwater-source total ammonia and the instream reaction coefficient for biological decay of total ammonia to total nitrite. Simulated dissolved-oxygen concentrations at all three sites are most sensitive to headwater-source dissolved-oxygen concentration. This input variable is the key source of variability for simulated dissolved-oxygen concentrations at sites 5 and 10. Headwatersource and point-source dissolved-oxygen concentrations are the key sources of variability for simulated dissolved-oxygen concentrations at site 14.During ice-free conditions, simulated specific-conductance values at all three sites are most sensitive to the headwater-source specific-conductance values. Headwater-source specificconductance values also are the key source of uncertainty. The input variables to which total ammonia and dissolved oxygen are most sensitive vary from site to site and may or may not correspond to the input variables that contribute the most to the variability. The input variables that contribute the most to the variability of simulated total ammonia concentrations are pointsource total ammonia, instream reaction coefficient for biological decay of total ammonia to total nitrite, and Manning's roughness coefficient. The input variables that contribute the most to the variability of simulated dissolved-oxygen concentrations are reaeration rate, sediment oxygen demand rate, and headwater-source algae as chlorophyll a.

Studies of the inner shelf and coastal sedimentation environment of the Beaufort Sea from ERTS-1

NASA Technical Reports Server (NTRS)

Reimnitz, E. (Principal Investigator)

1972-01-01

The author has identified the following significant results. Field studies of the initiation of river flow onto the frozen Arctic Ocean were made by a group of scientists from May 15 to June 10, 1972. A time lapse camera mounted on a 40-ft. tower near the mouth of the Kaparuk River, west of Prudhoe Bay, provided a detailed 10-day record (24 hours a day) of flow direction and water level. It is believed that wind build-up, discharge variance of the river, and through-ice drainage rates are the prime factors influencing overflow onto the sea ice. Current meter, transmissometer, temperature, salinity, and thermoprobe data were collected from holes drilled in the shorefast ice from seal holes and from the river water overflow. Depth and a real distribution of the overflow water were monitored from the ice using snowmobiles, and from the air using helicopters and fixed-wing aircraft. Photographic records were made on 35mm KII, KX, Ektachrome IR, Plus X, and IR black and white film. A simple two camera frame permitted simultaneous exposures of two types of film. Preliminary comparisons of the IR and conventional films, both color and black and white, showed no advantage to using the infrared film. However, the low altitude photography taken during this study will be very helpful in the interpretation of ERTS-1 imagery.

Effect of Interactive River Routing on North Atlantic Overturning in a Simulation of the last Deglaciation

NASA Astrophysics Data System (ADS)

Mikolajewicz, Uwe; Ziemen, Florian; Kapsch, Marie; Meccia, Virna

2017-04-01

One of the major challenges in climate modeling is the simulation of glacial-interglacial transitions. A few models of intermediate complexity have been successful in simulating the last termination. Complex atmosphere-ocean general circulation models (AOGCMs) with prescribed ice sheets are able to yield realistic climate changes. Here we present results from our first attempt to simulate a substantial part of the last glacial cycle with an AOGCM coupled interactively with a state-of-the-art ice sheet model. The ECHAM5/MPIOM AOGCM is interactively coupled to the dynamical ice sheet model PISM and the dynamical vegetation model LPJ. The model is integrated from the late Glacial into the Holocene using insolation and greenhouse gas concentrations as transient forcing. To make the long simulations feasible, the atmosphere is accelerated by a factor of 10 relative to the other components using a periodical-synchronous coupling technique. The land sea mask remains fixed at the LGM state. River routing and surface elevation are calculated interactively. A mini-ensemble with different initial conditions is performed. Additionally, one fully synchronously simulation, without acceleration in the atmosphere, is run. In all simulations the northern hemisphere deglaciation starts between 18 and 17 kyr BP, consistent with the onset of global warming. The model produces Heinrich event like variability. These rapid ice discharge events have a strong impact on the North Atlantic meridional overturning circulation (NAMOC). The interactive river routing has a strong impact on the simulated NAMOC during the deglaciation. The retreat of the Laurentide Ice Sheet together with the depressed topography due to the former ice load leads to a redirection of the river routes.. In particular, the discharge route for runoff from the melting southwestern Laurentide shifts from the Gulf of Mexico to the Arctic. The consequence is a rapid reduction/suppression of the North Atlantic deep water (NADW) formation. When the Laurentide Ice Sheet retreats from the Hudson Strait, this becomes the new drainage route. Hence, fresh water is released into the Labrador Sea and is less effective in suppressing the deep water formation in the North Atlantic. As a consequence, the NADW formation recovers within a few decades. Our results show the potential importance of interactive river routing for rapid changes in NAMOC strength during the deglaciation.

New age constraints for the Saalian glaciation in northern central Europe: Implications for the extent of ice sheets and related proglacial lake systems

NASA Astrophysics Data System (ADS)

Lang, Jörg; Lauer, Tobias; Winsemann, Jutta

2018-01-01

A comprehensive palaeogeographic reconstruction of ice sheets and related proglacial lake systems for the older Saalian glaciation in northern central Europe is presented, which is based on the integration of palaeo-ice flow data, till provenance, facies analysis, geomorphology and new luminescence ages of ice-marginal deposits. Three major ice advances with different ice-advance directions and source areas are indicated by palaeo-ice flow directions and till provenance. The first ice advance was characterised by a southwards directed ice flow and a dominance of clasts derived from southern Sweden. The second ice advance was initially characterised by an ice flow towards the southwest. Clasts are mainly derived from southern and central Sweden. The latest stage in the study area (third ice advance) was characterised by ice streaming (Hondsrug ice stream) in the west and a re-advance in the east. Clasts of this stage are mainly derived from eastern Fennoscandia. Numerical ages for the first ice advance are sparse, but may indicate a correlation with MIS 8 or early MIS 6. New pIRIR290 luminescence ages of ice-marginal deposits attributed to the second ice advance range from 175 ± 10 to 156 ± 24 ka and correlate with MIS 6. The ice sheets repeatedly blocked the main river-drainage pathways and led to the formation of extensive ice-dammed lakes. The formation of proglacial lakes was mainly controlled by ice-damming of river valleys and major bedrock spillways; therefore the lake levels and extends were very similar throughout the repeated ice advances. During deglaciation the lakes commonly increased in size and eventually drained successively towards the west and northwest into the Lower Rhine Embayment and the North Sea. Catastrophic lake-drainage events occurred when large overspill channels were suddenly opened. Ice-streaming at the end of the older Saalian glaciation was probably triggered by major lake-drainage events.

Effects of elevated temperatures and rising sea level on Arctic Coast

USGS Publications Warehouse

Barnes, Peter W.

1990-01-01

Ice is a major agent on the inner shelf, gouging the bottom, increasing hydraulic scour, transporting sediment, and influencing river flood patterns. Rapid coastal retreat is common and low barrier islands and beaches are constantly changing due to the influence of permafrost, ice-push, waves, and currents. Coastal processes are presently a balance between the influence of ice and the action of waves and currents. Quantitative values for processes are poorly known, however our qualitative understanding is nearly complete. Climatic warming and rising sea levels would decrease the temporal and aerial extent of coastal ice thereby expanding the role of waves and currents. As a result, shoreline retreat rates would increase, producing a transgressive erosional surface on the low coastal plain. With increased wave activity, beaches and barrier islands presently nourished by ice push processes would decay and disappear. Increased sediment supply from a deeply thawed, active layer would release more sediments to rivers and coasts. Additional research should be focused on permafrost and sea ice processes active during freeze up and breakup; the two seasons of most vigorous activity and change.

Optical and size characterization of dissolved organic matter from the lower Yukon River

NASA Astrophysics Data System (ADS)

Guo, L.; Lin, H.

2017-12-01

The Arctic rivers have experienced significant climate and environmental changes over the last several decades and their export fluxes and environmental fate of dissolved organic matter (DOM) have received considerable attention. Monthly or bimonthly water samples were collected from the Yukon River, one of the Arctic rivers, between July 2004 and September 2005 for size fractionation to isolate low-molecular-weight (LMW, <1 kDa) and high-molecular-weight (HMW, >1 kDa) DOM. The freeze-dried HMW-DOM was then characterized for their optical properties using fluorescence spectroscopy and colloidal size spectra using asymmetrical flow field-flow fractionation techniques. Ratios of biological index (BIX) to humification index (HIX) show a seasonal change, with lower values in river open seasons and higher values under the ice, and the influence of rive discharge. Three major fluorescence DOM components were identified, including two humic-like components (Ex/Em at 260/480 nm and 250/420 nm, respectively) and one protein-like component (Ex/Em=250/330). The ratio of protein-like to humic-like components was broadly correlated with discharge, with low values during spring freshet and high values under the ice. The relatively high protein-like/humic-like ratio during the ice-covered season suggested sources from macro-organisms and/or ice-algae. Both protein-like and humic-like colloidal fluorophores were partitioned mostly in the 1-5 kDa size fraction although the protein-like fluorophores in some samples also contained larger colloidal size. The relationship between chemical/biological reactivity and size/optical characteristics of DOM needs to be further investigated.

Post-glacial variations of sea ice cover and river discharge in the western Laptev Sea (Arctic Ocean) - a high-resolution study over the last 18 ka

NASA Astrophysics Data System (ADS)

Hörner, Tanja; Stein, Ruediger; Fahl, Kirsten

2015-04-01

Here, we provide a high-resolution reconstruction of sea-ice cover variations in the western Laptev Sea, a crucial area in terms of sea-ice production in the Arctic Ocean and a region characterized by huge river discharge. Furthermore, the shallow Laptev Sea was strongly influenced by the post-glacial sea-level rise that should also be reflected in the sedimentary records. The sea Ice Proxy IP25 (Highly-branched mono-isoprenoid produced by sea-ice algae; Belt et al., 2007) was measured in two sediment cores from the western Laptev Sea (PS51/154, PS51/159) that offer a high-resolution composite record over the last 18 ka. In addition, sterols are applied as indicator for marine productivity (brassicasterol, dinosterol) and input of terrigenous organic matter by river discharge into the ocean (campesterol, ß-sitosterol). The sea-ice cover varies distinctly during the whole time period and shows a general increase in the Late Holocene. A maximum in IP25 concentration can be found during the Younger Dryas. This sharp increase can be observed in the whole circumarctic realm (Chukchi Sea, Bering Sea, Fram Strait and Laptev Sea). Interestingly, there is no correlation between elevated numbers of ice-rafted debris (IRD) interpreted as local ice-cap expansions (Taldenkova et al. 2010), and sea ice cover distribution. The transgression and flooding of the shelf sea that occurred over the last 16 ka in this region, is reflected by decreasing terrigenous (riverine) input, reflected in the strong decrease in sterol (ß-sitosterol and campesterol) concentrations. References Belt, S.T., Massé, G., Rowland, S.J., Poulin, M., Michel, C., LeBlanc, B., 2007. A novel chemical fossil of palaeo sea ice: IP25. Organic Geochemistry 38 (1), 16e27. Taldenkova, E., Bauch, H.A., Gottschalk, J., Nikolaev, S., Rostovtseva, Yu., Pogodina, I., Ya, Ovsepyan, Kandiano, E., 2010. History of ice-rafting and water mass evolution at the northern Siberian continental margin (Laptev Sea) during Late Glacial and Holocene times. Quaternary Science Reviews 29 (27-28), 3919-3935.

High-resolution record of last post-glacial variations of sea-ice cover and river discharge in the western Laptev Sea (Arctic Ocean)

NASA Astrophysics Data System (ADS)

Stein, R. H.; Hörner, T.; Fahl, K.

2014-12-01

Here, we provide a high-resolution reconstruction of sea-ice cover variations in the western Laptev Sea, a crucial area in terms of sea-ice production in the Arctic Ocean and a region characterized by huge river discharge. Furthermore, the shallow Laptev Sea was strongly influenced by the post-glacial sea-level rise that should also be reflected in the sedimentary records. The sea Ice Proxy IP25 (Highly-branched mono-isoprenoid produced by sea-ice algae; Belt et al., 2007) was measured in two sediment cores from the western Laptev Sea (PS51/154, PS51/159) that offer a high-resolution composite record over the last 18 ka. In addition, sterols are applied as indicator for marine productivity (brassicasterol, dinosterol) and input of terrigenous organic matter by river discharge into the ocean (campesterol, ß-sitosterol). The sea-ice cover varies distinctly during the whole time period and shows a general increase in the Late Holocene. A maximum in IP25 concentration can be found during the Younger Dryas. This sharp increase can be observed in the whole circumarctic realm (Chukchi Sea, Bering Sea, Fram Strait and Laptev Sea). Interestingly, there is no correlation between elevated numbers of ice-rafted debris (IRD) interpreted as local ice-cap expansions (Taldenkova et al. 2010), and sea ice cover distribution. The transgression and flooding of the shelf sea that occurred over the last 16 ka in this region, is reflected by decreasing terrigenous (riverine) input, reflected in the strong decrease in sterol (ß-sitosterol and campesterol) concentrations. ReferencesBelt, S.T., Massé, G., Rowland, S.J., Poulin, M., Michel, C., LeBlanc, B., 2007. A novel chemical fossil of palaeo sea ice: IP25. Organic Geochemistry 38 (1), 16e27. Taldenkova, E., Bauch, H.A., Gottschalk, J., Nikolaev, S., Rostovtseva, Yu., Pogodina, I., Ya, Ovsepyan, Kandiano, E., 2010. History of ice-rafting and water mass evolution at the northern Siberian continental margin (Laptev Sea) during Late Glacial and Holocene times. Quaternary Science Reviews 29 (27-28), 3919-3935.

Thermal processes of thermokarst lakes in the continuous permafrost zone of northern Siberia - observations and modeling (Lena River Delta, Siberia)

NASA Astrophysics Data System (ADS)

Boike, J.; Georgi, C.; Kirilin, G.; Muster, S.; Abramova, K.; Fedorova, I.; Chetverova, A.; Grigoriev, M.; Bornemann, N.; Langer, M.

2015-10-01

Thermokarst lakes are typical features of the northern permafrost ecosystems, and play an important role in the thermal exchange between atmosphere and subsurface. The objective of this study is to describe the main thermal processes of the lakes and to quantify the heat exchange with the underlying sediments. The thermal regimes of five lakes located within the continuous permafrost zone of northern Siberia (Lena River Delta) were investigated using hourly water temperature and water level records covering a 3-year period (2009-2012), together with bathymetric survey data. The lakes included thermokarst lakes located on Holocene river terraces that may be connected to Lena River water during spring flooding, and a thermokarst lake located on deposits of the Pleistocene Ice Complex. Lakes were covered by ice up to 2 m thick that persisted for more than 7 months of the year, from October until about mid-June. Lake-bottom temperatures increased at the start of the ice-covered period due to upward-directed heat flux from the underlying thawed sediment. Prior to ice break-up, solar radiation effectively warmed the water beneath the ice cover and induced convective mixing. Ice break-up started at the beginning of June and lasted until the middle or end of June. Mixing occurred within the entire water column from the start of ice break-up and continued during the ice-free periods, as confirmed by the Wedderburn numbers, a quantitative measure of the balance between wind mixing and stratification that is important for describing the biogeochemical cycles of lakes. The lake thermal regime was modeled numerically using the FLake model. The model demonstrated good agreement with observations with regard to the mean lake temperature, with a good reproduction of the summer stratification during the ice-free period, but poor agreement during the ice-covered period. Modeled sensitivity to lake depth demonstrated that lakes in this climatic zone with mean depths > 5 m develop continuous stratification in summer for at least 1 month. The modeled vertical heat flux across the bottom sediment tends towards an annual mean of zero, with maximum downward fluxes of about 5 W m-2 in summer and with heat released back into the water column at a rate of less than 1 W m-2 during the ice-covered period. The lakes are shown to be efficient heat absorbers and effectively distribute the heat through mixing. Monthly bottom water temperatures during the ice-free period range up to 15 °C and are therefore higher than the associated monthly air or ground temperatures in the surrounding frozen permafrost landscape. The investigated lakes remain unfrozen at depth, with mean annual lake-bottom temperatures of between 2.7 and 4 °C.

Ice Streams as the Critical Link Between the Interior Ice Reservoir of the Antarctic Ice Sheet and the Global Climate System - a WISSARD Perspective (Invited)

NASA Astrophysics Data System (ADS)

Tulaczyk, S. M.; Beem, L.; Walter, J. I.; Hossainzadeh, S.; Mankoff, K. D.

2010-12-01

Fast flowing ice streams represent crucial features of the Antarctic ice sheet because they provide discharge ‘valves’ for the interior ice reservoir and because their grounding lines are exposed to ocean thermal forcing. Even with no/little topographic control ice flow near the perimeter of a polar ice sheet self-organizes into discrete, fast-flowing ice streams. Within these features basal melting (i.e. lubrication for ice sliding) is sustained through elevated basal shear heating in a region of thin ice that would otherwise be characterized by basal freezing and slow ice motion. Because faster basal ice motion is typically associated with faster subglacial erosion, ice streams tend to localize themselves over time by carving troughs into underlying rocks and sediments. Debris generated by this erosional activity is carried to the continental shelf and/or continental slope where it may be deposited at very high rates, rivaling these associated with deposition by some of the largest rivers on Earth. In terms of their hydrologic and geological functions, Antarctic ice streams play pretty much the same role as rivers do on non-glaciated continents. However, understanding of their dynamics is still quite rudimentary, largely because of the relative inaccessibility of the key basal and marine boundaries of ice streams where pertinent measurements need to be made. The present elevated interest in predicting future contribution of Antarctica to global sea level changes is driving ambitious research programs aimed at scientific exploration of these poorly investigated environments that will play a key role in defining the response of the ice sheet to near future climate changes. We will review one of these programs, the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) with particular focus on its planned contributions to understanding of ice stream dynamics.

Projected Impact of Climate Change on the Water and Salt Budgets of the Arctic Ocean by a Global Climate Model

NASA Technical Reports Server (NTRS)

Miller, James R.; Russell, Gary L.

1996-01-01

The annual flux of freshwater into the Arctic Ocean by the atmosphere and rivers is balanced by the export of sea ice and oceanic freshwater. Two 150-year simulations of a global climate model are used to examine how this balance might change if atmospheric greenhouse gases (GHGs) increase. Relative to the control, the last 50-year period of the GHG experiment indicates that the total inflow of water from the atmosphere and rivers increases by 10% primarily due to an increase in river discharge, the annual sea-ice export decreases by about half, the oceanic liquid water export increases, salinity decreases, sea-ice cover decreases, and the total mass and sea-surface height of the Arctic Ocean increase. The closed, compact, and multi-phased nature of the hydrologic cycle in the Arctic Ocean makes it an ideal test of water budgets that could be included in model intercomparisons.

75 FR 8486 - Regulated Navigation Area; Hudson River south of the Troy Locks, New York

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-25

...-AA11 Regulated Navigation Area; Hudson River south of the Troy Locks, New York AGENCY: Coast Guard, DHS... area on the navigable waters of the Hudson River south of the Troy Locks. This regulated navigation... Hudson River south of the Troy locks when ice conditions are 8 inches or greater unless authorized by the...

75 FR 76943 - Regulated Navigation Area; Hudson River South of the Troy Locks, NY

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-10

...-AA11 Regulated Navigation Area; Hudson River South of the Troy Locks, NY AGENCY: Coast Guard, DHS... Navigation Area (RNA) on the navigable waters of the Hudson River in New York, south of the Troy Locks. This... within the waters of the Hudson River south of the Troy Locks when ice is a threat to navigation. DATES...

76 FR 8654 - Regulated Navigation Area; Hudson River South of the Troy Locks, NY

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-15

...-AA11 Regulated Navigation Area; Hudson River South of the Troy Locks, NY AGENCY: Coast Guard, DHS... navigable waters of the Hudson River in New York, south of the Troy Locks. This action is necessary to... Hudson River south of the Troy Locks when ice is a threat to navigation. DATES: This rule is effective in...

Infill of tunnel valleys associated with landward-flowing ice sheets: The missing Middle Pleistocene record of the NW European rivers?

NASA Astrophysics Data System (ADS)

Moreau, Julien; Huuse, Mads

2014-01-01

The southern termination of the Middle and Late Pleistocene Scandinavian ice sheets was repeatedly located in the southern North Sea (sNS) and adjacent, north-sloping land areas. Giant meltwater-excavated valleys (tunnel valleys) formed at the southern termination of the ice sheets and contain a hitherto enigmatic succession of northward prograding clinoforms, comprising 1000s km3 of sediment. This study analyses 3D seismic data, covering the entire sNS, and demonstrates for the first time that the formation of these tunnel valleys was separate from their infill. The infill constitutes the postglacial record of the NW European river deltas, which had so far been considered missing.

Transport and Degradation of Dissolved Organic Matter and Associated Freshwater Pathways in the Laptev Sea (Siberian Arctic)

NASA Astrophysics Data System (ADS)

Hoelemann, J. A.; Janout, M. A.; Koch, B.; Bauch, D.; Novikhin, A.; Heim, B.; Eulenburg, A.; Kassens, H.; Timokhov, L.

2016-02-01

The Siberian shelves are seasonally ice-covered and characterized by large freshwater runoff rates from some of the largest rivers on earth. These rivers also provide a considerable amount of dissolved organic carbon (DOC) to the Arctic Ocean. With an annual load of about 6 Tg DOC a-1 the Lena River contributes nearly 20 percent of the annual DOC discharge to the Arctic Ocean. We present a comprehensive dataset collected during multiple Laptev Sea expeditions carried out in spring, summer and fall (2010-15) in order to explore the processes controlling the dispersal and degradation of DOM during the river water's passage across the shelf. Our investigations are focused on CDOM (Colored Dissolved Organic Matter), which resembles the DOC concentration, interacts with solar radiation and forms a major fraction of the organic matter pool. Our results show an inverse correlation between salinity and CDOM, which emphasizes its terrigenous source. Further, the spectral slope of CDOM absorption indicates that photochemical bleaching is the main process that reduces the CDOM absorption ( 20%) in freshwater along its transport across the shelf. The distribution of the Lena river water is primarily controlled by winds in summer. During summers with easterly or southerly winds, the plume remains on the central and northern Laptev shelf, and is available for export into the Arctic Basin. The CDOM-rich river water increases the absorption of solar radiation and enhances warming of a shallow surface layer. This emphasizes the importance of CDOM for sea surface temperatures and lateral ice melt on the shelf and adjacent basin. DOC concentrations in freshwater vary seasonally and become larger with increasing discharge. Our data indicate that the CDOM concentrations are highest during the freshet when landfast ice is still present. Subsequent mixing with local sea ice meltwater lowers CDOM to values that are characteristic for the Lena freshwater during the rest of the year.

Transport and degradation of dissolved organic matter and associated freshwater pathways in the Laptev Sea (Siberian Arctic)

NASA Astrophysics Data System (ADS)

Hoelemann, Jens; Janout, Markus; Koch, Boris; Bauch, Dorothea; Hellmann, Sebastian; Eulenburg, Antje; Heim, Birgit; Kassens, Heidemarie; Timokhov, leonid

2016-04-01

The Siberian shelves are seasonally ice-covered and characterized by large freshwater runoff rates from some of the largest rivers on earth. These rivers also provide a considerable amount of dissolved organic carbon (DOC) to the Arctic Ocean. With an annual load of about 6 Tg DOC a-1 the Lena River contributes nearly 20 percent of the annual DOC discharge to the Arctic Ocean. We present a comprehensive dataset collected during multiple Laptev Sea expeditions carried out in spring, summer and fall (2010-15) in order to explore the processes controlling the dispersal and degradation of DOM during the river water's passage across the shelf. Our investigations are focused on CDOM (Colored Dissolved Organic Matter), which resembles the DOC concentration, interacts with solar radiation and forms a major fraction of the organic matter pool. Our results show an inverse correlation between salinity and CDOM, which emphasizes its terrigenous source. Further, the spectral slope of CDOM absorption indicates that photochemical bleaching is the main process that reduces the CDOM absorption (~ 20%) in freshwater along its transport across the shelf. The distribution of the Lena river water is primarily controlled by winds in summer. During summers with easterly or southerly winds, the plume remains on the central and northern Laptev shelf, and is available for export into the Arctic Basin. The CDOM-rich river water increases the absorption of solar radiation and enhances warming of a shallow surface layer. This emphasizes the importance of CDOM for sea surface temperatures and lateral ice melt on the shelf and adjacent basin. DOC concentrations in freshwater vary seasonally and become larger with increasing discharge. Our data indicate that the CDOM concentrations are highest during the freshet when landfast ice is still present. Subsequent mixing with local sea ice meltwater lowers CDOM to values that are characteristic for the Lena freshwater during the rest of the year.

Long-term ice phenology records from eastern-central Europe

NASA Astrophysics Data System (ADS)

Takács, Katalin; Kern, Zoltán; Pásztor, László

2018-03-01

A dataset of annual freshwater ice phenology was compiled for the largest river (Danube) and the largest lake (Lake Balaton) in eastern-central Europe, extending regular river and lake ice monitoring data through the use of historical observations and documentary records dating back to AD 1774 and AD 1885, respectively. What becomes clear is that the dates of the first appearance of ice and freeze-up have shifted, arriving 12-30 and 4-13 days later, respectively, per 100 years. Break-up and ice-off have shifted to earlier dates by 7-13 and 9-27 days/100 years, except on Lake Balaton, where the date of break-up has not changed significantly. The datasets represent a resource for (paleo)climatological research thanks to the strong, physically determined link between water and air temperature and the occurrence of freshwater ice phenomena. The derived centennial records of freshwater cryophenology for the Danube and Balaton are readily available for detailed analysis of the temporal trends, large-scale spatial comparison, or other climatological purposes. The derived dataset is publicly available via PANGAEA at https://doi.org/10.1594/PANGAEA.881056.

The Unprecedented 2016-2017 Arctic Sea Ice Growth Season: The Crucial Role of Atmospheric Rivers and Longwave Fluxes

NASA Astrophysics Data System (ADS)

Hegyi, Bradley M.; Taylor, Patrick C.

2018-05-01

The 2016-2017 Arctic sea ice growth season (October-March) exhibited one of the lowest values for end-of-season sea ice volume and extent of any year since 1979. An analysis of Modern-Era Retrospective Analysis for Research and Applications, Version 2 atmospheric reanalysis data and Clouds and the Earth's Radiant Energy System radiative flux data reveals that a record warm and moist Arctic atmosphere supported the reduced sea ice growth. Numerous regional episodes of increased atmospheric temperature and moisture, transported from lower latitudes, increased the cumulative energy input from downwelling longwave surface fluxes. In those same episodes, the efficiency of the atmosphere cooling radiatively to space was reduced, increasing the amount of energy retained in the Arctic atmosphere and reradiated back toward the surface. Overall, the Arctic radiative cooling efficiency shows a decreasing trend since 2000. The results presented highlight the increasing importance of atmospheric forcing on sea ice variability demonstrating that episodic Arctic atmospheric rivers, regions of elevated poleward water vapor transport, and the subsequent surface energy budget response is a critical mechanism actively contributing to the evolution of Arctic sea ice.

Poleward upgliding Siberian atmospheric rivers over sea ice heat up Arctic upper air.

PubMed

Komatsu, Kensuke K; Alexeev, Vladimir A; Repina, Irina A; Tachibana, Yoshihiro

2018-02-13

We carried out upper air measurements with radiosondes during the summer over the Arctic Ocean from an icebreaker moving poleward from an ice-free region, through the ice edge, and into a region of thick ice. Rapid warming of the Arctic is a significant environmental issue that occurs not only at the surface but also throughout the troposphere. In addition to the widely accepted mechanisms responsible for the increase of tropospheric warming during the summer over the Arctic, we showed a new potential contributing process to the increase, based on our direct observations and supporting numerical simulations and statistical analyses using a long-term reanalysis dataset. We refer to this new process as "Siberian Atmospheric Rivers (SARs)". Poleward upglides of SARs over cold air domes overlying sea ice provide the upper atmosphere with extra heat via condensation of water vapour. This heating drives increased buoyancy and further strengthens the ascent and heating of the mid-troposphere. This process requires the combination of SARs and sea ice as a land-ocean-atmosphere system, the implication being that large-scale heat and moisture transport from the lower latitudes can remotely amplify the warming of the Arctic troposphere in the summer.

Chronology of the last glacial maximum in the upper Bear River Basin, Utah

USGS Publications Warehouse

Laabs, B.J.C.; Munroe, Jeffrey S.; Rosenbaum, J.G.; Refsnider, K.A.; Mickelson, D.M.; Singer, B.S.; Caffee, M.W.

2007-01-01

The headwaters of the Bear River drainage were occupied during the Last Glacial Maximum (LGM) by outlet glaciers of the Western Uinta Ice Field, an extensive ice mass (???685 km2) that covered the western slope of the Uinta Mountains. A well-preserved sequence of latero-frontal moraines in the drainage indicates that outlet glaciers advanced beyond the mountain front and coalesced on the piedmont. Glacial deposits in the Bear River drainage provide a unique setting where both 10Be cosmogenic surface-exposure dating of moraine boulders and 14C dating of sediment in Bear Lake downstream of the glaciated area set age limits on the timing of glaciation. Limiting 14C ages of glacial flour in Bear Lake (corrected to calendar years using CALIB 5.0) indicate that ice advance began at 32 ka and culminated at about 24 ka. Based on a Bayesian statistical analysis of cosmogenic surface-exposure ages from two areas on the terminal moraine complex, the Bear River glacier began its final retreat at about 18.7 to 18.1 ka, approximately coincident with the start of deglaciation elsewhere in the central Rocky Mountains and many other alpine glacial localities worldwide. Unlike valleys of the southwestern Uinta Mountains, deglaciation of the Bear River drainage began prior to the hydrologie fall of Lake Bonneville from the Provo shoreline at about 16 ka. ?? 2007 Regents of the University of Colorado.

Preliminary observations of voluminous ice-rich and water-rich lahars generated during the 2009 eruption of Redoubt, Alaska

USGS Publications Warehouse

Waythomas, Christopher F.; Pierson, Thomas C.; Major, Jon J.; Scott, William E.

2012-01-01

Redoubt Volcano in south-central Alaska began erupting on March 15, 2009, and by April 4, 2009, had produced at least 20 explosive events that generated plumes of ash and lahars. The 3,108-m high, snow- and -ice-clad stratovolcano has an ice-filled summit crater that is breached to the north. The volcano supports about 4 km3 of ice and snow and about 1 km3 of this makes up the Drift glacier on the northern side of the volcano. Explosive eruptions between March 22 and April 4, which included the destruction of at least two lava domes, triggered significant lahars in the Drift River valley on March 23 and April 4 and several smaller lahars between March 24 and March 31. High-flow marks, character of deposits, areas of inundation, and estimates of flow velocity revealed that the lahars on March 23 and April 4 were the largest of the eruption. In the 2-km-wide upper Drift River valley, average flow depths were about 3–5 m. Average peak-flow velocities were likely between 10 and 15 ms-1, and peak discharges were on the order of 104–105 m3s-1. The area inundated by lahars on March 23 was at least 100 km2 and on April 4 about 125 km2. The lahars emplaced on March 23 and April 4 had volumes on the order of 107–108 m3 and were similar in size to the largest lahar of the 1989–90 eruption. The March 23 lahars were primarily flowing slurries of snow and ice entrained from the Drift glacier and seasonal snow and tabular blocks of river ice from the Drift River valley. Only a single, undifferentiated deposit up to 5 m thick was found and contained about 80–95 percent of poorly sorted, massive to imbricate assemblages of snow and ice. The deposit was frozen soon after it was emplaced and later eroded and buried by the April 4 lahar. The lahar of April 4, in contrast, was primarily a hyperconcentrated flow, as interpreted from 1- to 6-m thick deposits of massive to horizontally stratified sand-to-fine-gravel. Rock material in the April 4 lahar deposit is predominantly juvenile andesite. We infer that the lahars generated on March 23 were initiated by a rapid succession of vent-clearing explosions that blasted through about 50–100 m of crater-filling glacier ice and snow, producing a voluminous release of meltwater from the Drift glacier. The resulting flood eroded and entrained snow, fragments of glacier and river ice, and liquid water along its flow path. Small-volume pyroclastic flows, possibly associated with destruction of a small dome or minor eruption-column collapses, may have contributed additional meltwater to the lahar. Meltwater generated by subglacial hydrothermal activity and stored beneath the Drift glacier may have been ejected or released rapidly as well. The April 4 lahar was initiated when hot dome-collapse pyroclastic flows entrained and swiftly melted snow and ice, and incorporated additional rock debris from the Drift glacier. The peak discharge of the April 4 lahar was in the range of 60,000–160,000 m3s-1. For comparison, the largest lahar of the 1989–90 eruption had a peak discharge of about 80,000 m3s-1. Lahars generated by the 2009 eruption led to significant channel aggradation in the lower Drift River valley and caused extensive inundation at an oil storage and transfer facility located there. The April 4, 2009, lahar was 6–30 times larger than the largest meteorological floods known or estimated in the Drift River drainage.

Remedial Investigation Report: White Phosphorus Contamination of Salt Marsh Sediments at Eagle River Flats, Alaska

DTIC Science & Technology

1992-03-31

ponds (Bread Truck Pond) were significantly higher than those from the other ponds. Area C and the Bread Truck ponds, covering an area of about 15 ha (37...Figure 1-12. Aerial view of Eagle River Flats in January 1991 viewed to the north showing Knik Arm and ice- covered ERF. Figure 11-13. Ice core...levees of some distributaries are tall stands of beach rye (Elymus arenarius). Inside or landward of this sparsely vegetated mudflat zone is a low sedge

Quantifying changes in the contribution of upstream snow and glacier melt to downstream low flows in the River Rhine

NASA Astrophysics Data System (ADS)

Stahl, K.; Kohn, I.; Boehm, M.; Seibert, J.; Freudiger, D.; Gerlinger, K.; Weiler, M.

2016-12-01

Low flows impact river ecosystems and impair water use. In the mid- and downstream reaches of one of the largest rivers in Europe, the River Rhine, low flows can threaten a variety of ecosystem services and direct uses. Low flows in summer and fall are sustained by the snow and ice melt contribution from the glacierized mountain headwaters upstream. This study explores changes in the discharge components of rain, snowmelt and ice melt during extreme low flow events from a downstream perspective. Quantification of the discharge components is based on a novel method of runoff component tracking that was implemented into a model chain, consisting of the HBV model, which includes a glacier mass balance model allowing for areal glacier changes, for the headwaters and the distributed hydrological model LARSIM for the remaining Rhine basin. A transient model run at daily resolution was calibrated to glacier volume change, basin-wide snow cover and snow water equivalent and discharge variability at many gauging stations over the period 1901-2006. The analysis of the resulting discharge components revealed that over the course of the 20th Century, the loss of glacier volume and glacier area in the headwaters appears to have compensated an increasingly negative glacier mass balance, resulting in little long-term change to the ice melt component in summer streamflow - thus showing no clear `peak-water' trend. While the glacier ice melt component was less than two percent of the average annual discharge of the mid and lower reaches of the River Rhine, models suggest its fraction was much higher during extreme low flow events. The low flows of the summers of 1921, 1947, and 2003 were comprised of record daily ice melt fractions of more than one fifth of the daily discharge along the mid and lower reaches from Basel to the mouth. A scenario model run with suppressed glacier area change suggests that the ice melt discharge component would have doubled if the same meteorological event as in 2003 had occurred in the early 1900s when glacier areas were still much larger. Impacts on ecology and water use most likely would have also been less severe. The modeled changes in discharge components thus allow a quantification of the low flow hazard that may loom ahead as the glaciers continue to decline.

Stable oxygen isotope variability in two contrasting glacier river catchments in Greenland

NASA Astrophysics Data System (ADS)

Yde, Jacob C.; Knudsen, Niels T.; Steffensen, Jørgen P.; Carrivick, Jonathan L.; Hasholt, Bent; Ingeman-Nielsen, Thomas; Kronborg, Christian; Larsen, Nicolaj K.; Mernild, Sebastian H.; Oerter, Hans; Roberts, David H.; Russell, Andrew J.

2016-03-01

Analysis of stable oxygen isotope (δ18O) characteristics is a useful tool to investigate water provenance in glacier river systems. In order to attain knowledge on the diversity of δ18O variations in Greenlandic rivers, we examined two contrasting glacierised catchments disconnected from the Greenland Ice Sheet (GrIS). At the Mittivakkat Gletscher river, a small river draining a local temperate glacier in southeast Greenland, diurnal oscillations in δ18O occurred with a 3 h time lag to the diurnal oscillations in run-off. The mean annual δ18O was -14.68 ± 0.18 ‰ during the peak flow period. A hydrograph separation analysis revealed that the ice melt component constituted 82 ± 5 % of the total run-off and dominated the observed variations during peak flow in August 2004. The snowmelt component peaked between 10:00 and 13:00 local time, reflecting the long travel time and an inefficient distributed subglacial drainage network in the upper part of the glacier. At the Kuannersuit Glacier river on the island Qeqertarsuaq in west Greenland, the δ18O characteristics were examined after the major 1995-1998 glacier surge event. The mean annual δ18O was -19.47 ± 0.55 ‰. Despite large spatial variations in the δ18O values of glacier ice on the newly formed glacier tongue, there were no diurnal oscillations in the bulk meltwater emanating from the glacier in the post-surge years. This is likely a consequence of a tortuous subglacial drainage system consisting of linked cavities, which formed during the surge event. Overall, a comparison of the δ18O compositions from glacial river water in Greenland shows distinct differences between water draining local glaciers and ice caps (between -23.0 and -13.7 ‰) and the GrIS (between -29.9 and -23.2 ‰). This study demonstrates that water isotope analyses can be used to obtain important information on water sources and the subglacial drainage system structure that is highly desired for understanding glacier hydrology.

Understanding of changes in river flow using recently collected field and observational data from Russian Arctic

NASA Astrophysics Data System (ADS)

Shiklomanov, A. I.; Tokarev, I. V.; Davydov, S. P.; Davydova, A.; Streletskiy, D. A.

2017-12-01

There is substantial evidence supporting increasing river runoff in the Eurasian pan-Arctic, but the causes of these changes are not well understood. To determine the contributions of various water sources to river runoff generation in small streams and large rivers located in the continuous permafrost zone, an extensive field campaign was carried out near the town of Cherskii, Russia. Measurements of hydrometeorological characteristics, as well as stable isotope composition and hydrochemistry of precipitation, river flow and ground ice, were obtained during the 2013-2016 period. When combined with older data (2005-2009), the isotopic composition of atmospheric precipitation showed a general trend towards heavier winter precipitation, attributed mainly to observed increases in winter air temperature. Samples of water and ground ice from several boreholes showed that isotopic compositions of water from the active layer, transient layer and permafrost are significantly different. Thus, stable isotopes can be used to assess contributions of different soil layers to stream flow generation. Increases in streamflow of small test watersheds were observed during dry periods in August-September. These increases were associated with considerable stable isotope depletion in streamflow samples, which is likely caused by thawing of the transient- and possibly upper permafrost layers. The absence of correlation between water and air temperature during these periods (R2 = 0.22 in August-September and R2 = 0.8 in June-July) also suggests an increasing contribution of thawing ground ice to the streamflow. To quantitatively assess the contribution of various water sources to the river runoff of Kolyma River, we used stable isotope data along with a physically based hydrological model developed at the University of New Hampshire. Preliminary results suggest that thawing permafrost increased August-September discharge in Kolyma near Cherskii by 8% in 2013, 11% in 2014 and 4% in 2015, even though none of these years was extremely warm or wet. We estimate that 5cm of permafrost thaw (with 30% ice content) over the entire Kolyma basin can contribute about 10 km3/year (or 10%) to annual discharge and significantly change the water regime during low-flow periods (fall-winter).

Effects of Hydroelectric Dam Operations on the Restoration Potential of Snake River Fall Chinook Salmon (Oncorhynchus tshawytscha) Spawning Habitat Final Report, October 2005 - September 2007.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanrahan, Timothy P.; Richmond, Marshall C.; Arntzen, Evan V.

2007-11-13

This report describes research conducted by the Pacific Northwest National Laboratory for the Bonneville Power Administration (BPA) as part of the Fish and Wildlife Program directed by the Northwest Power and Conservation Council. The study evaluated the restoration potential of Snake River fall Chinook salmon spawning habitat within the impounded lower Snake River. The objective of the research was to determine if hydroelectric dam operations could be modified, within existing system constraints (e.g., minimum to normal pool levels; without partial removal of a dam structure), to increase the amount of available fall Chinook salmon spawning habitat in the lower Snakemore » River. Empirical and modeled physical habitat data were used to compare potential fall Chinook salmon spawning habitat in the Snake River, under current and modified dam operations, with the analogous physical characteristics of an existing fall Chinook salmon spawning area in the Columbia River. The two Snake River study areas included the Ice Harbor Dam tailrace downstream to the Highway 12 bridge and the Lower Granite Dam tailrace downstream approximately 12 river kilometers. These areas represent tailwater habitat (i.e., riverine segments extending from a dam downstream to the backwater influence from the next dam downstream). We used a reference site, indicative of current fall Chinook salmon spawning areas in tailwater habitat, against which to compare the physical characteristics of each study site. The reference site for tailwater habitats was the section extending downstream from the Wanapum Dam tailrace on the Columbia River. Fall Chinook salmon spawning habitat use data, including water depth, velocity, substrate size and channelbed slope, from the Wanapum reference area were used to define spawning habitat suitability based on these variables. Fall Chinook salmon spawning habitat suitability of the Snake River study areas was estimated by applying the Wanapum reference reach habitat suitability criteria to measured and modeled habitat data from the Snake River study areas. Channel morphology data from the Wanapum reference reach and the Snake River study areas were evaluated to identify geomorphically suitable fall Chinook salmon spawning habitat. The results of this study indicate that a majority of the Ice Harbor and Lower Granite study areas contain suitable fall Chinook salmon spawning habitat under existing hydrosystem operations. However, a large majority of the currently available fall Chinook salmon spawning habitat in the Ice Harbor and Lower Granite study areas is of low quality. The potential for increasing, through modifications to hydrosystem operations (i.e., minimum pool elevation of the next downstream dam), the quantity or quality of fall Chinook salmon spawning habitat appears to be limited. Estimates of the amount of potential fall Chinook salmon spawning habitat in the Ice Harbor study area decreased as the McNary Dam forebay elevation was lowered from normal to minimum pool elevation. Estimates of the amount of potential fall Chinook salmon spawning habitat in the Lower Granite study area increased as the Little Goose Dam forebay elevation was lowered from normal to minimum pool elevation; however, 97% of the available habitat was categorized within the range of lowest quality. In both the Ice Harbor and Lower Granite study areas, water velocity appears to be more of a limiting factor than water depth for fall Chinook salmon spawning habitat, with both study areas dominated by low-magnitude water velocity. The geomorphic suitability of both study areas appears to be compromised for fall Chinook salmon spawning habitat, with the Ice Harbor study area lacking significant bedforms along the longitudinal thalweg profile and the Lower Granite study area lacking cross-sectional topographic diversity. To increase the quantity of available fall Chinook salmon spawning habitat in the Ice Harbor and Lower Granite study area, modifications to hydroelectric dam operations beyond those evaluated in this study likely would be necessary. Modifications may include operational and structural changes, such as lowering downstream dam forebay elevations to less than minimum pool. There is a large amount of uncertainty as to whether or not such modifications could increase the quantity of available fall Chinook salmon spawning habitat in the Ice Harbor and Lower Granite study area. The results from this study provide some certainty that the quantity and quality of fall Chinook salmon spawning habitat within the lower Snake River are not likely to be increased within the existing hydroelectric dam operations.« less

A remote-sensing, GIS-based approach to identify, characterize, and model spawning habitat for fall-run chum salmon in a sub-arctic, glacially fed river

USGS Publications Warehouse

Wirth, Lisa; Rosenberger, Amanda; Prakash, Anupma; Gens, Rudiger; Margraf, F. Joseph; Hamazaki, Toshihide

2012-01-01

At northern limits of a species’ distribution, fish habitat requirements are often linked to thermal preferences, and the presence of overwintering habitat. However, logistical challenges and hydrologic processes typical of glacial systems could compromize the identification of these habitats, particularly in large river environments. Our goal was to identify and characterize spawning habitat for fall-run chum salmon Oncorhynchus keta and model habitat selection from spatial distributions of tagged individuals in the Tanana River, Alaska using an approach that combined ground surveys with remote sensing. Models included braiding, sinuosity, ice-free water surface area (indicating groundwater influence), and persistent ice-free water (i.e., consistent presence of ice-free water for a 12-year period according to satellite imagery). Candidate models containing persistent ice-free water were selected as most likely, highlighting the utility of remote sensing for monitoring and identifying salmon habitat in remote areas. A combination of ground and remote surveys revealed spatial and temporal thermal characteristics of these habitats that could have strong biological implications. Persistent ice-free sites identified using synthetic aperture radar appear to serve as core areas for spawning fall chum salmon, and the importance of stability through time suggests a legacy of successful reproductive effort for this homing species. These features would not be captured with a one-visit traditional survey but rather required remote-sensing monitoring of the sites through time.

ROV dives under Great Lakes ice

USGS Publications Warehouse

Bolsenga, S.J.; Gannon, John E.; Kennedy, Gregory; Norton, D.C.; Herdendorf, Charles E.

1989-01-01

Observations of the underside of ice have a wide variety of applications. Severe under-ice roughness can affect ice movements, rough under-ice surfaces can scour the bottom disturbing biota and man-made structures such as pipelines, and the flow rate of rivers is often affected by under-ice roughness. A few reported observations of the underside of an ice cover have been made, usually by cutting a large block of ice and overturning it, by extensive boring, or by remote sensing. Such operations are extremely labor-intensive and, in some cases, prone to inaccuracies. Remotely operated vehicles (ROV) can partially solve these problems. In this note, we describe the use, performance in a hostile environment, and results of a study in which a ROV was deployed under the ice in Lake Erie (North American Great Lakes).

Atmospheric rivers causing high accumulation storms in East Antarctica: regional climate model evaluation

NASA Astrophysics Data System (ADS)

Lazzara, M. A.; Tsukernik, M.; Gorodetskaya, I.

2016-12-01

Recent studies confirmed that atmospheric rivers (ARs) reach the continent of Antarctica and thus influence the Antarctic accumulation patterns and the ice sheet mass balance (Gorodetskaya et al. 2014, GRL). Similar to mid-latitude ARs, Antarctic ARs are associated with a blocking pattern downstream of a cyclone, which allows channeling of moisture toward the continent. However, due to the extremely cold atmosphere, Antarctic ARs possess some unique features. First, the existence of an AR in high latitudes is always associated with warm advection. Second, in order for an AR to penetrate the continent, it needs to overcome strong low-level outflow winds - katabatic winds - coming from the interior of the continent. Thirdly, sea ice surrounding the Antarctic ice sheet introduces an additional "cold barrier" decreasing the tropospheric moisture holding capacity and promoting precipitation before reaching the ice sheet. We believe these factors contribute to the scarcity of AR events influencing the ice sheet surface mass balance. Nevertheless, their presence is clearly seen in the long-term record. In particular, anomalous accumulation in 2009 and 2011 in Dronning Maud Land in East Antarctica has been linked to atmospheric rivers. We performed a detailed investigation of several AR storm events from 2009 and 2011 using the Weather Research and Forecasting (WRF) model simulations. These simulations depicted the synoptic scale development of storms that led to an anomalous precipitation pattern in the East Antarctic. We investigated the role of the upper level vs. lower level forcing in the formation of the contributing storms. The moisture and temperature anomalies of each case are evaluated in the context of synoptic and large-scale atmospheric forcing. We also performed sensitivity studies to determine the role of sea ice in the development of these systems.

Nitrogen cycling processes and microbial community composition in bed sediments in the Yukon River at Pilot Station

USGS Publications Warehouse

Repert, Deborah A.; Underwood, Jennifer C.; Smith, Richard L.; Song, Bongkeun

2014-01-01

Information on the contribution of nitrogen (N)-cycling processes in bed sediments to river nutrient fluxes in large northern latitude river systems is limited. This study examined the relationship between N-cycling processes in bed sediments and N speciation and loading in the Yukon River near its mouth at the Bering Sea. We conducted laboratory bioassays to measure N-cycling processes in sediment samples collected over distinct water cycle seasons. In conjunction, the microbial community composition in the bed sediments using genes involved in N-cycling (narG, napA, nosZ, and amoA) and 16S rRNA gene pyrosequences was examined. Temporal variation was observed in net N mineralization, nitrate uptake, and denitrification rate potentials and correlated strongly with sediment carbon (C) and extractable N content and microbial community composition rather than with river water nutrient concentrations. The C content of the bed sediment was notably impacted by the spring flood, ranging from 1.1% in the midst of an ice-jam to 0.1% immediately after ice-out, suggesting a buildup of organic material (OM) prior to scouring of the bed sediments during ice break up. The dominant members of the microbial community that explained differences in N-processing rates belonged to the genera Crenothrix,Flavobacterium, and the family of Comamonadaceae. Our results suggest that biogeochemical processing rates in the bed sediments appear to be more coupled to hydrology, nutrient availability in the sediments, and microbial community composition rather than river nutrient concentrations at Pilot Station.

Interannual kinetics (2010-2013) of large wood in a river corridor exposed to a 50-year flood event and fluvial ice dynamics

NASA Astrophysics Data System (ADS)

Boivin, Maxime; Buffin-Bélanger, Thomas; Piégay, Hervé

2017-02-01

Semi-alluvial rivers of the Gaspé Peninsula, Québec, are prone to produce and transport vast quantities of large wood (LW). The high rate of lateral erosion owing to high energy flows and noncohesive banks is the main process leading to the recruitment of large wood, which in turn initiates complex patterns of wood accumulation and reentrainment within the active channel. The delta of the Saint-Jean River (SJR) has accumulated large annual wood fluxes since 1960 that culminated in a wood raft of > 3-km in length in 2014. To document the kinetics of large wood on the main channel of SJR, four annual surveys were carried out from 2010 to 2013 to locate and describe > 1000 large wood jams (LWJ) and 2000 large wood individuals (LWI) along a 60-km river section. Airborne and ground photo/video images were used to estimate the wood volume introduced by lateral erosion and to identify local geomorphic conditions that control wood mobility and deposits. Video camera analysis allowed the examination of transport rates from three hydrometeorological events for specific river sections. Results indicate that the volume of LW recruited between 2010 and 2013 represents 57% of the total LW production over the 2004-2013 period. Volumes of wood deposited along the 60-km section were four times higher in 2013 than in 2010. Increases in wood amount occurred mainly in upper alluvial sections of the river, whereas decreases were observed in the semi-alluvial middle sections. Observations suggest that the 50-year flood event of 2010 produced large amounts of LW that were only partly exported out of the basin so that a significant amount was still available for subsequent floods. Large wood storage continued after this flood until a similar flood or an ice-breakup event could remobilise these LW accumulations into the river corridor. Ice-jam floods transport large amounts of wood during events with fairly low flow but do not contribute significantly to recruitment rates (ca. 10 to 30% early). It is fairly probable that the wood export peak observed in 2012 at the river mouth, where no flood occurred and which is similar to the 1-in 10-year flood of 2010, is mainly linked to such ice-break events that occurred in March 2012.

Monitoring of Streambank Stabilization and River Restoration Structures on Ice-Affected Rivers in Northern Vermont

DTIC Science & Technology

2009-08-01

Site Characteristics River Site Drainage Area ( mi2 ) Valley Bottom Slope Bank- full Width (ft) Bank- full Depth (ft) Bankfull...relatively unaltered by human activities. Drainage areas range from 990 ERDC/CRREL TR-09-14 17 mi2 on the lower Winooski to 44 mi2 on the upper Trout

Estimating ice-affected streamflow by extended Kalman filtering

USGS Publications Warehouse

Holtschlag, D.J.; Grewal, M.S.

1998-01-01

An extended Kalman filter was developed to automate the real-time estimation of ice-affected streamflow on the basis of routine measurements of stream stage and air temperature and on the relation between stage and streamflow during open-water (ice-free) conditions. The filter accommodates three dynamic modes of ice effects: sudden formation/ablation, stable ice conditions, and eventual elimination. The utility of the filter was evaluated by applying it to historical data from two long-term streamflow-gauging stations, St. John River at Dickey, Maine and Platte River at North Bend, Nebr. Results indicate that the filter was stable and that parameters converged for both stations, producing streamflow estimates that are highly correlated with published values. For the Maine station, logarithms of estimated streamflows are within 8% of the logarithms of published values 87.2% of the time during periods of ice effects and within 15% 96.6% of the time. Similarly, for the Nebraska station, logarithms of estimated streamflows are within 8% of the logarithms of published values 90.7% of the time and within 15% 97.7% of the time. In addition, the correlation between temporal updates and published streamflows on days of direct measurements at the Maine station was 0.777 and 0.998 for ice-affected and open-water periods, respectively; for the Nebraska station, corresponding correlations were 0.864 and 0.997.

Himalayan Lake- and River-Impacting Landslides and Ice Avalanches: Some So Deadly, Some No Problem

NASA Astrophysics Data System (ADS)

Kargel, J. S.; Karki, A.; Haritashya, U. K.; Shugar, D. H.; Harrison, S.

2017-12-01

Scientific attention to landslides and ice avalanches in Nepal was heightened by the 2015 Gorkha earthquake. However, landslides and ice avalanches— some deadly— are frequent in this mountainous, glacierized country and across High Mountain Asia. River blocking landslides (RBLs) often create dangerous situations due to upstream impoundments and downstream landslide dammed outburst floods (LDOFs). Factors affecting RBL hazards include: Volumes and masses of ice, rock, and water; shape factors of the valley and landslide; grain size-frequency distribution; river hydrograph; and seasonal and weather factors. These factors affect processes such as slumping and erosion of the RBL by overflow or piping, buoyant lifting of dam material, melting of a landslide ice core, liquefaction, overfill overtopping or tsunami overtopping by subsequent landslides into the impoundment, and the volume and peak discharge of an LDOF. Not all processes aggravate hazards; a high ice:rock ratio, for example, can result in immediate tunneling by the river with no subsequent impoundment. A dam composed of mainly boulders with few fines likewise can prevent effective damming; however, a wide spectrum of the particle-size-distribution can make a long-lasting, benign dam. The most hazardous RBLs include those creating large dams and rapidly-filled impoundments, but which can rapidly and catastrophically break up, especially at sites of repeated terrain collapses. The particle size-frequency of a landslide dam depends substantially on bedrock lithology and structure. Vulnerabilities and warning times also affect whether an upstream impoundment flood or LDOF will exert a large toll. For landslide susceptibility assessments, usual treatments involving mountain slopes, valley shape, and seismic activity should be complemented by quantitative measures of bedrock lithology and weathering state, the potential energy and distribution of unstable masses, and recorded historic or prehistoric RBLs in the same area. Factors for landslide triggering of glacial lake outburst floods (GLOFs) include some of the same factors, but the mass/energy input rate into the lake, the lake's shape and length, and moraine dam properties are also important in GLOF triggering. Himalayan examples will illustrate some hazard factors.

Assessment of the Relationship between Andean Ice Core Precipitation Indicators and Amazon River Discharge

NASA Astrophysics Data System (ADS)

Johnson, N.; Alsdorf, D.; Thompson, L.; Mosley-Thompson, E.; Melack, J.

2006-12-01

Prior to the last 100 years, there is a significant lack of hydrologic knowledge for the Amazon Basin. A 100- year record of discharge from the city of Manaus, located at the confluence of the Solimoes and Negro rivers, is the most complete record for the basin. Inundated wetlands play a key role in carbon out-gassing to the atmosphere whereas discharge from the Amazon River contributes about 20% of the total freshwater flux delivered to the world's oceans. As discharge (Q) and inundation are directly related to precipitation, we are developing a method to extend our understanding of Q and inundation into the 19^{th} century. Using proxy data preserved in Andean glaciers and ice caps and recovered from ice cores, annually resolved histories of δ^{18)O and mass accumulation are available. The latter is a proxy for local precipitation amount whereas δ18O is influenced by continental scale processes (i.e., evaporation, convection) as well as by temperature and hence, by varying climate regimes. We have correlated the accumulation and δ18O records from Core 1 drilled on the Quelccaya ice-cap in the southern Andes of Peru with the Manaus discharge data. As ice core annual layers correspond to the thermal year (in Peru, July to June of the following year) and the discharge records are kept daily (January to December), we averaged 365 days of Q data seeking the optimal correlation for each start and end date. The best statistical relationship between δ18O and Q (r = -0.41, p = < 0.001) is attained when Q is averaged from March 16 to March 15 of the following year. We also correlated 23 years of ENSO events, which are linked to both Amazon River discharge and ice core δ18O (r = -0.60, p = < 0.001). These linear relationships are used to create Amazon discharge for the 20^{th} century and to extrapolate Q into the 19^{th} century. Previously developed relationships between Q and mainstem inundated area are then used to estimate inundated area along the main Amazon channel for the past 200 years. The ice core-derived estimate of inundated area for the past 100 years compares well with the previous and more straightforward estimates based on discharge and remote sensing data.

Floods of April 1952 in the Missouri River basin

USGS Publications Warehouse

Wells, J.V.B.

1955-01-01

The floods of April 1952 in the Milk River basin, along the Missouri River from the mouth of the Little Missouri River to the mouth of the Kansas River, and for scattered tributaries of the Missouri River in North and South Dakota were the greatest ever observed. The damage amounted to an estimated $179 million. The outstanding featur6 of the floods was the extraordinary peak discharge generated in the Missouri River at and downstream from Bismarck, N. Dak., on April 6 when a large ice jam upstream from the city was suddenly released. Inflow from flooding tributaries maintained the peak discharge at approximately the same magnitude in the transit of the flood across South Dakota; downstream from Yankton, S. Dak., attenuation of the peak discharge was continuous because of natural storage in the wide flood plains. The outstanding characteristic of floods in the Milk River basin was their duration--the flood crested at Havre, Mont., on April 3 and at Nashua, Mont.. on April 18. The floods were caused by an abnormally heavy accumulation of snow that was converted into runoff in a few days of very warm weather at the end of March. The heaviest water content of the snow pack at breakup was in a narrow arc extending through Aberdeen, S. Dak., Pierre, S. Dak.. and northwestward toward the southwest corner of North Dakota. The water content in part of this concentrated cover exceeded 6 inches. The winter of 1951-52, which followed a wet cold fall that made the ground impervious, was one of the most severe ever experienced in South Dakota and northern Montana. Depths of snow and low temperatures combined to produce, at the end of March, one of the heaviest snow covers in the history of the Great Plains. The Missouri River ice was intact upstream from Chamberlain, S. Dak., at the end of March, and the breakup of the ice with inflow of local runoff was one of the spectacular features of the flood. Runoff from the Yellowstone River combining with the flood pouring from the Little Missouri River caused the Missouri River to crest at an all-time high at Elbowoods, N. Dak., on April 4. As this crest moved downstream to Bismarck, its intensity was increased by the alternate storing and release of ice jams plus the inflow from the Knife River. The crest discharge of 500,000 cfs came at Bismarck at 6 p. m. on April 6. following a very sharp rise from 80,000 cfs at 11 a.m. Overflow occurred along the Missouri River from Elbowoods to the mouth with high damage to cities. farmland, and installations located in the flood plain. Cleanup and repair operations following the flood continued for many weeks. Few of the flooded farms produced a crop during 1952. This report presents detailed records of stage and discharge for the flood period on the Missouri River and tributaries from Fort Peck. Mont., to the mouth. Information on damages and river stages collected by other agencies is also presented.

Coastal environment of the Beaufort Sea from field data and ERTS-1 imagery, summer 1972

NASA Technical Reports Server (NTRS)

Reimnitz, E. (Principal Investigator); Barnes, P. W.

1972-01-01

The author has identified the following significant results. An extensive field program during the spring and summer in the coastal Beaufort Sea test site has been completed using a wide variety of sensing techniques. Reduction of field data and ERTS-1 image analysis have shown the coastal environment to be complexly influenced by unique processes, most of which involve or are related to sea ice. Active sedimentologic processes along the Arctic coast are set in motion by the melting, flooding, and eventual overflow of rivers onto the sea ice. It is now apparent that only minor amounts of sediment are transported offshore at this stage; however, scouring of the bottom is significant beneath the strudels (drain holes) which develop in the fast ice canopy in the region of overflow. Areal salinity and turbidity patterns together with ERTS-1 imagery confirm a consistent influx of colder, clearer, saltier water towards the coast just east of the Colville River. Strong (up to 3 knots) bidirectional but intermittent currents often manifest themselves in imagery and aerial photographs as wakes behind grounded ice. Ice movement vectors generated from repetitive images indicate that ice drift is closely associated with wind direction, especially in shallow bays, and displacements of 4-22 kilometers were noted in 24 hours.

Flooding of the Ob River, Russia

NASA Technical Reports Server (NTRS)

2002-01-01

A mixture of heavy rainfall, snowmelt, and ice jams in late May and early June of this year caused the Ob River and surrounding tributaries in Western Siberia to overflow their banks. The flooding can be seen in thess image taken on June 16, 2002, by the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Terra satellite. Last year, the river flooded farther north. Normally, the river resembles a thin black line, but floods have swollen the river considerably. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

Integrated Optical and SAR Imagery with DEM to Quantify Glacier Water Storage Change in Upper Mekong River Basin

NASA Astrophysics Data System (ADS)

Liu, G. T.; Chen, J. B.; Le, T. S.; Chang, C. P.; Shum, C. K.; Tseng, K. H.

2015-12-01

In the past few decades, regional increase in air temperature has accelerated the ice melting in polar, sub-polar, and major land glacial areas. The glaciers in Tibetan Plateau, the largest glaciers outside Polar Regions and the sources of several trans-boundary major rivers, are now showing aggravated terminus retreat and thinning. The variation of freshwater availability is crucial for the economic development in Mainland Southeast Asia, especially in hydroelectric generation and agriculture irrigation. These rives, including the Mekong River, is also subject to upstream-downstream conflict and transboundary issues. In this study, we propose to estimate the remaining glacier water storage in Mekong River basin, and further analyze the impact of glacier retreat on these dams/reservoirs for the next decade. By calculating the Modified Normalized Difference Water Index (MNDWI), the water surface area (WSA) can thus be extracted from optical satellite images. On the other hand, the ice surface area (ISA) can be derived from the Polarimetric Synthetic Aperture Radar (POLSAR) images. With different polarization states of electromagnetic wave reflected by earth surface, POLSAR image can effectively identify glacier/ice from snow. Combined WSA and ISA information with digital elevation model (DEM), the change of freshwater storage in glaciers can be estimated. In the end, the influence on dams/reservoirs in the Mekong River caused by glacier retreat can be forecasted. The result can also be applied to hydrology, water allocation, and economy/agriculture policy determination.

Extreme rates of riverbank erosion of the high bluff formed by the ice-rich syngenetic permafrost (yedoma), Itkillik River, Northern Alaska

NASA Astrophysics Data System (ADS)

Kanevskiy, M. Z.; Shur, Y.; Fortier, D.; Jorgenson, T.; Stephani, E.; Strauss, J.

2013-12-01

Riverbank erosion in areas underlain by ice-rich permafrost is strongly affected by the processes of thawing of ground ice, which include (1) thermal erosion, and (2) thermal denudation. Thermal erosion is a process of combined thermal and mechanical action of moving water, which results in simultaneous thawing of frozen soil and its removal by water. Thermal erosion can cause block collapse of eroded banks. Thermal denudation is a process of thawing of frozen soils exposed in the bluff due to solar energy and consequent removal of thawed soils by gravity. Studies of riverbank and coastal erosion revealed that the highest rates of erosion are typical of bluffs composed by yedoma (ice- and organic-rich syngenetically frozen silty deposits). Yedoma deposits can be up to 50 m thick, and they contain huge ice wedges up to 10 m wide. Since 2006, we have studied the process of riverbank erosion of the 35 m high exposure of yedoma along the Itkillik River in northern Alaska. Based on five measurements of the areas occupied by wedge ice in panoramic photographs taken in 2006, 2007, 2011, and 2012, the average wedge-ice volume makes 61% of the entire exposed bluff. The total volumetric ground ice content of the Itkillik yedoma, including wedge, segregated and pore ice, is 85%. We detect three main stages of the riverbank erosion for the study site and other similar sites in the areas of ice-rich permafrost: (1) thermal erosion combined with thermal denudation, (2) thermal denudation, and (3) slope stabilization. The first stage includes formation of thermoerosional niches; development of sub-vertical cracks and block-fall collapse of cornices; and thawing and disintegration of blocks of ground ice and frozen soil in the water. All these processes are accompanied by thermal denudation of the exposed bluff. On August 16, 2007, a big portion of the bluff fell down along the crack sub-parallel to the bluff. As a result, the vertical wall more than 65 m long entirely formed by the wedge ice was exposed. This block-fall affected the area of approximately 800 m2, and the volume of frozen soil and ice involved in the block-fall was about 15,000 m3. The riverbank retreat due to thermal erosion and/or thermal denudation, measured from August 2007 to August 2011, varied from less than 10 to almost 100 m. An estimated retreat rate average for the whole 680 m long bluff was 11.4 m/year, but for the most actively eroded central part of the bluff (150 m long) it was 20.3 m/year, ranging from 16 to 24 m/year. During these 4 years, about 650,000 m3 of ice and organic-rich frozen soil were transported to the river from the retreating bank (more than 160,000 m3/year). Analysis of aerial photographs (1948-1979) and satellite images (1974-2013) showed that the riverbank was relatively stable till July 1995, when the Itkillik River changed its course and triggered extremely active thermal erosion. The total retreat of the riverbank in 1995-2010 varied from 180 to 280 m, which means that the average retreat rate for the most actively eroded part of the riverbank reached almost 19 m/year. Such a high rate of riverbank erosion over a long time period has not been reported before for any permafrost regions of Eurasia and North America.

Sediment entrainment into sea ice and transport in the Transpolar Drift: A case study from the Laptev Sea in winter 2011/2012

NASA Astrophysics Data System (ADS)

Wegner, C.; Wittbrodt, K.; Hölemann, J. A.; Janout, M. A.; Krumpen, T.; Selyuzhenok, V.; Novikhin, A.; Polyakova, Ye.; Krykova, I.; Kassens, H.; Timokhov, L.

2017-06-01

Sea ice is an important vehicle for sediment transport in the Arctic Ocean. On the Laptev Sea shelf (Siberian Arctic) large volumes of sediment-laden sea ice are formed during freeze-up in autumn, then exported and transported across the Arctic Ocean into Fram Strait where it partly melts. The incorporated sediments are released, settle on the sea floor, and serve as a proxy for ice-transport in the Arctic Ocean on geological time scales. However, the formation process of sediment-laden ice in the source area has been scarcely observed. Sediment-laden ice was sampled during a helicopter-based expedition to the Laptev Sea in March/April 2012. Sedimentological, biogeochemical and biological studies on the ice core as well as in the water column give insights into the formation process and, in combination with oceanographic process studies, on matter fluxes beneath the sea ice. Based on satellite images and ice drift back-trajectories the sediments were likely incorporated into the sea ice during a mid-winter coastal polynya near one of the main outlets of the Lena River, which is supported by the presence of abundant freshwater diatoms typical for the Lena River phytoplankton, and subsequently transported about 80 km northwards onto the shelf. Assuming ice growth of 12-19 cm during this period and mean suspended matter content in the newly formed ice of 91.9 mg l-1 suggests that a minimum sediment load of 8.4×104 t might have been incorporated into sea ice. Extrapolating these sediment loads for the entire Lena Delta region suggests that at least 65% of the estimated sediment loads which are incorporated during freeze-up, and up to 10% of the annually exported sediment load may be incorporated during an event such as described in this paper.

Assessing conditions influencing the longitudinal distribution of exotic brown trout (Salmo trutta) in a mountain stream: a spatially-explicit modeling approach

USGS Publications Warehouse

Meredith, Christy S.; Budy, Phaedra; Hooten, Mevin B.; Oliveira Prates, Marcos

2017-01-01

Trout species often segregate along elevational gradients, yet the mechanisms driving this pattern are not fully understood. On the Logan River, Utah, USA, exotic brown trout (Salmo trutta) dominate at low elevations but are near-absent from high elevations with native Bonneville cutthroat trout (Onchorhynchus clarkii utah). We used a spatially-explicit Bayesian modeling approach to evaluate how abiotic conditions (describing mechanisms related to temperature and physical habitat) as well as propagule pressure explained the distribution of brown trout in this system. Many covariates strongly explained redd abundance based on model performance and coefficient strength, including average annual temperature, average summer temperature, gravel availability, distance from a concentrated stocking area, and anchor ice-impeded distance from a concentrated stocking area. In contrast, covariates that exhibited low performance in models and/or a weak relationship to redd abundance included reach-average water depth, stocking intensity to the reach, average winter temperature, and number of days with anchor ice. Even if climate change creates more suitable summer temperature conditions for brown trout at high elevations, our findings suggest their success may be limited by other conditions. The potential role of anchor ice in limiting movement upstream is compelling considering evidence suggesting anchor ice prevalence on the Logan River has decreased significantly over the last several decades, likely in response to climatic changes. Further experimental and field research is needed to explore the role of anchor ice, spawning gravel availability, and locations of historical stocking in structuring brown trout distributions on the Logan River and elsewhere.

The Environmental Evaluation Work Group Fiscal Year 1979 Studies of the Winter Navigation Demonstration Program. Effects of Ship-Induced Waves in an Ice Environment on the St. Marys River Ecosystem

DTIC Science & Technology

1979-07-27

April 17-21, immediately after the solid ice cover had been broken up by heavy vessel traffic. 4. 1acroinvertebrates of 56 taxa were identified in 75...clams), Amphipoda (scuds), Polychaeta, Ephemeroptera (mayflies), and Trichoptera (caddisflies) were common in all samples and collectively made up about...period of solid ice cover. Comparison of drift net catches in March when there was solid ice cover and moderate vessel traffic with catches in April

75 FR 78928 - Limited Service Domestic Voyage Load Lines for River Barges on Lake Michigan, Delay of Effective...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-17

... Advisories may also be issued when lake ice exists that could be hazardous to small boats. Although river...-AA17 Limited Service Domestic Voyage Load Lines for River Barges on Lake Michigan, Delay of Effective... Lake Michigan. This rule finalized interim regulations that have been in effect since 2002, with some...

Influence of the Yukon River on the Bering Sea

NASA Technical Reports Server (NTRS)

Dean, K.; Mcroy, C. P.

1986-01-01

The relationships between the discharge of the Yukon River to the currents and biological productivity in the northern Bering Sea were studied. Specific objectives were: to develop thermal, sediment, and chlorophyll surface maps using Thematic Mapper (TM) data of the discharge of the Yukon River and the Alaskan Coastal Current during the ice free season; to develop a historical model of the distribution of the Yukon River discharge and the Alaskan Coastal Current using LANDSAT Multispectral band scanner (MSS) and NOAA satellite imagery; and to use high resolution TM data to define the surface dynamics of the front between the Alaskan Coastal Current and the Bering Shelf/Anadyr Current. LANDSAT MSS, TM, and Advanced Very High Resolution Radiometer (AVHRR) data were recorded during the 1985 ice free period. The data coincided with shipboard measurements acquired by Inner Shelf Transfer and Recycling (ISTAR) project scientists. An integrated model of the distribution of turbid water discharged from the Yukon River was compiled. A similar model is also being compiled for the Alaskan Coastal and Bering Shelf/Anadyr water masses based on their thermal expressions seen on AVHRR imagery.

Ice Atlas 1985 - 1986. Monongahela River, Allegheny River, Ohio River, Illinois River and Kankakee River.

DTIC Science & Technology

1987-11-01

Des P/o,,nes River Grant Cut -off V 1Kankrokee Cut- off Drsdn slndCountyI Line Bordwell Isi. V _ KankakeKRiver 2 */0 7r Prairle Cr 6 0 1 M1 Survey date...2 x 10 6t 81 279 River 279 13 February 1986 275 Kankak Des P/amnes RIver Gran7 Cree Cut-off DrsenIladCount y Line Bordwell Isr. 0 1 M1 ’kornkokee A...Gat Cut - off KankakeeFiver ’e Drsdn slndCounty Line Bordwell s 1 mi 2urve date FerarM1,i Kankakee River :2.4 oCr. 󈧢 X9Kankakcee River :14 ML 0- 5𔃿

Boundary Waves on the Ice Surface Created by Currents

NASA Astrophysics Data System (ADS)

Naito, K.; Izumi, N.; Yokokawa, M.; Yamada, T.; de Lima, A. C.

2013-12-01

The formation of periodic boundary waves, e.g. antidunes and cyclic steps (Parker & Izumi 2000) has been known to be caused by instabilities between flow and bed (e.g. Engelund 1970), and are observed not only on river beds or ocean floors but also on ice surfaces, such as the surface of glaciers and underside of river ice (Carey 1966). In addition, owing to recent advancements of remote sensing technology, it has been found that the surfaces of the polar ice caps on Mars as well as on the Earth have step-like formations (Smith & Holt 2010) which are assumed to be boundary waves, because they are generated perpendicularly to the direction of the currents. These currents acting on the polar ice caps are density airflow, i.e. katabatic wind (Howard et al 2000). The comprehension of the formation process of the Martian polar ice caps may reveal climate changes which have occurred on Mars. Although the formation of boundary waves on river beds or ocean floors has been studied by a number of researchers, there are few works on their formation on ice surfaces. Yokokawa et al (2013) suggested that the temperature distribution of the ambient air, fluid and ice is a factor which determines the direction of migration of boundary waves formed on ice surfaces through their experiments. In this study, we propose a mathematical model in order to describe the formation process of the boundary waves and the direction of their migration. We consider that a liquid is flowing through a flume filled with a flat ice layer on the bottom. The flow is assumed to be turbulent and its temperature is assumed to merge with the ambient temperature at the flow surface and with the melting point of ice at the bottom (ice surface). The ice surface evolution is dependent on the unbalance between the interfacial heat flux of the liquid and ice, and we employ the Reynolds-averaged Navier-Stokes equation, the continuity equation, heat transfer equations for the liquid and ice, and a heat balance equation at the flow-ice interface. It is assumed that the interfacial heat fluxes of the liquid and ice are determined by the temperature profile, and the Reynolds stress and the turbulent heat flux are expressed by the eddy diffusivity of momentum and the eddy diffusivity of heat, respectively. In addition, the liquid can be divided into two layers; viscous sublayer and turbulent layer. In order to determine the velocity and temperature profile in the liquid, we employ the Prandtl-Taylor analogy which assumes that the velocity profile follows a linear law in the viscous sublayer and a logarithmic law in the turbulent layer, and the eddy diffusivity of heat is described by the eddy diffusivity of momentum and Prandtl number of the liquid. Finally, we obtain the temperature profiles (because the heat transfer equation for the ice reduces to the Laplace equation, the temperature profile in the ice can be easily estimated) and interfacial heat fluxes.

Transient Fluvial Response to Alpine Deglaciation, Mount Rainier, WA: Geomorphic Process Domains and Proglacial Flux Controls on Channel Evolution.

NASA Astrophysics Data System (ADS)

Beyeler, J. D.; Montgomery, D.; Kennard, P. M.

2016-12-01

Downwasting of all glaciers on the flanks of Mount Rainier, WA, in recent decades has debuttressed Little Ice Age glaciogenic sediments driving proglacial responses to regionally warming climate. Rivers draining the deglaciating edifice are responding to paraglacial sedimentation processes through transient storage of retreat-liberated sediments in aggrading (e.g., >5m) fluvial networks with widening channel corridors (i.e., 50-150%) post-LIA (ca., 1880-1910 locally). We hypothesize that the downstream transmission of proglacial fluxes (i.e., sediment and water) through deglaciating alpine terrain is a two-step geomorphic process. The ice-proximal portion of the proglacial system is dominated by the delivery of high sediment-to-water ratio flows (i.e., hyperconcentrated and debris slurries) and sediment retention by in-channel accumulation (e.g., confined debris fans within channel margins of valley segments) exacerbated by recruitment and accumulation of large wood (e.g., late seral stage conifers), whereas ice-distal fluvial reworking of transient sediment accumulations generates downstream aggradation. Historical Carbon River observations show restricted ice-proximal proglacial aggradation until a mainstem avulsion in 2009 initiated incision into sediment accumulations formed in recent decades, which is translating into aggradation farther down the network. Surficial morphology mapped with GPS, exposed subsurface sedimentology, and preliminary dating of buried trees suggest a transitional geomorphic process zone has persisted along the proglacial Carbon River through recent centuries and prior to the ultimate LIA glaciation. Structure-from-motion DEM differencing through the 2016 water year shows discrete zones of proglacial evolution through channel-spanning bed aggradation forced by interactions between large wood and sediment-rich flows that transition to fluvial process dominance as sediment is transported downstream. Long-term DEM differencing suggests these are persistent geomorphic processes as rivers respond to alpine deglaciation. This process-based study implies downstream river flooding in deglaciating alpine terrain globally is driven by glaciogenic sediment release and downstream channel aggradation irrespective of changes in discharge.

Meltwater palaeohydrology of the Baker River basin (Chile/Argentina) during Late Pleistocene deglaciation of the Northern Patagonia Icefield

NASA Astrophysics Data System (ADS)

Thorndycraft, Varyl; Bendle, Jacob; Benito, Gerardo; Sancho, Carlos; Palmer, Adrian; Rodríguez, Xavier

2016-04-01

The Late Pleistocene deglaciation of the Northern Patagonia Icefield (NPI) was characterised by rapid ice sheet thinning and retreat, and the development of large proglacial lake systems characterised by continental scale drainage reversals. In this region, research has focused primarily on the identification of former ice-limits (e.g. moraine ridges) for geochronological analyses, with little attention given to the meltwater palaeohydrology of major river valleys. The Baker River catchment drains the majority of the eastern ice shed of the NPI, with a basin area of 29,000 km2 that includes the large transboundary lakes of General Carrera/Buenos Aires and Cochrane/Puerreydón. The Baker River valley is aligned north to south, crossing the east-west valleys of the main NPI outflow glaciers, and thus represents an important aspect of regional Late Pleistocene palaeogeography. The Baker River valley therefore has the potential to refine regional models of deglaciation through better understanding of relationships between glacier dynamics, ice dammed lakes and meltwater pathways. Here we present geomorphological mapping from the Atlantic-Pacific drainage divide (over 150 km east of the Cordillera) to the lower Baker valley, in order to reconstruct Late Pleistocene palaeohydrology. We provide new mapping of palaeolake shoreline elevations and evidence for glacial lake outburst flood (GLOF) pathways that require a re-evaluation of the currently accepted palaeogeographic models. For example, the palaeohydrological evidence does not support existing models of a unified Buenos Aires/Puerreydón mega-lake at ca. 400m elevation. We propose a relative chronology of palaeohydrological events that help refine the published moraine chronology derived from cosmogenic nuclide exposure dating. Controls on Late Pleistocene meltwater palaeohydrology of the Baker catchment are discussed, including the interplay of glacial processes and regional tectonics, in particular, dynamic topography.

Fine scale monitoring of ice ablation following convective heat transfer: case study based on ice-wedge thermo-erosion on Bylot Island (Canadian High Arctic) and laboratory observations

NASA Astrophysics Data System (ADS)

Godin, E.; Fortier, D.

2011-12-01

Thermo-erosion gullies often develop in ice-wedge polygons terrace and contribute to the dynamic evolution of the periglacial landscape. When snowmelt surface run-off concentrated into streams and water tracks infiltrate frost cracks, advective heat flow and convective thermal transfer from water to the ice-wedge ice enable the rapid development of tunnels and gullies in the permafrost (Fortier et al. 2007). Fine scale monitoring of the physical interaction between flowing water and ice rich permafrost had already been studied in a context of thermal erosion of a large river banks in Russia (Costard et al. 2003). Ice wedge polygons thermo-erosion process leading to gullying remains to be physically modelled and quantified. The present paper focus on the fine scale monitoring of thermo-erosion physical parameters both in the field and in laboratory. The physical model in laboratory was elaborated using a fixed block of ice monitored by a linear voltage differential transducer (LVDT) and temperature sensors connected to a logger. A water container with controlled discharge and temperature provided the fluid which flowed over the ice through a hose. Water discharge (Q), water temperature (Tw), ice melting temperature (Ti) and ice ablation rate (Ar) were measured. In laboratory, water at 281 Kelvin (K) flowing on the ice (Ti 273 K) made the ice melt at a rate Ar of 0.002 m min-1, under a continuous discharge of ≈ 8 x 10-7 m3 s-1. In the field, a small channel was dug between a stream and an exposed ice-wedge in a pre-existing active gully, where in 2010 large quantities of near zero snowmelt run-off water contributed to several meters of ice wedge ablation and gully development. Screws were fastened into the ice and a ruler was used to measure the ablation rate every minute. The surface temperature of the ice wedge was monitored with thermocouples connected to a logger to obtain the condition of the ice boundary layer. Discharge and water temperature were measured in the excavated channel just before the water got in contact with the ice surface. The field experiment where flowing water at Tw = 277 K, Ti = 273 K with a water discharge of 0.01 m3 s-1 resulted in a measured Ar of 0.01 to 0.02 m min-1. Water discharge and temperature difference between water and the melting ice were fundamental to ice ablation rate. The recent climate warming in the Canadian High Arctic will likely strongly contribute to the interaction and importance of the thermo-erosion and gullying processes in the High Arctic. Combined factors such as earlier or faster snowmelt, precipitation changes during the summer and positive feedback effects will probably increase the hydrological input to gullies and therefore enhance their development by thermo-erosion. Costard F. et al. 2003. Fluvial thermal erosion investigations along a rapidly eroding river bank: Application to the Lena River (central Siberia). Earth Surface Processes and Landforms 28: 1349-1359. Fortier D. et al. 2007. Observation of rapid drainage system development by thermal erosion of ice wedges on Bylot island, Canadian Arctic Archipelago. Permafrost and Periglacial Processes 18: 229-243.

Permafrost Organic Carbon Mobilization From the Watershed to the Colville River Delta: Evidence From 14C Ramped Pyrolysis and Lignin Biomarkers

NASA Astrophysics Data System (ADS)

Zhang, Xiaowen; Bianchi, Thomas S.; Cui, Xingqian; Rosenheim, Brad E.; Ping, Chien-Lu; Hanna, Andrea J. M.; Kanevskiy, Mikhail; Schreiner, Kathryn M.; Allison, Mead A.

2017-11-01

The deposition of terrestrial-derived permafrost particulate organic carbon (POC) has been recorded in major Arctic river deltas. However, associated transport pathways of permafrost POC from the watershed to the coast have not been well constrained. Here we utilized a combination of ramped pyrolysis-oxidation radiocarbon analysis (RPO 14C) along with lignin biomarkers, to track the linkages between soils and river and delta sediments. Surface and deep soils showed distinct RPO thermographs which may be related to degradation and organo-mineral interaction. Soil material in the bed load of the river channel was mostly derived from deep old permafrost. Both surface and deep soils were transported and deposited to the coast. Hydrodynamic sorting and barrier island protection played important roles in terrestrial-derived permafrost POC deposition near the coast. On a large scale, ice processes (e.g., ice gauging and strudel scour) and ocean currents controlled the transport and distribution of permafrost POC on the Beaufort Shelf.

Surface water mass composition changes captured by cores of Arctic land-fast sea ice

NASA Astrophysics Data System (ADS)

Smith, I. J.; Eicken, H.; Mahoney, A. R.; Van Hale, R.; Gough, A. J.; Fukamachi, Y.; Jones, J.

2016-04-01

In the Arctic, land-fast sea ice growth can be influenced by fresher water from rivers and residual summer melt. This paper examines a method to reconstruct changes in water masses using oxygen isotope measurements of sea ice cores. To determine changes in sea water isotope composition over the course of the ice growth period, the output of a sea ice thermodynamic model (driven with reanalysis data, observations of snow depth, and freeze-up dates) is used along with sea ice oxygen isotope measurements and an isotopic fractionation model. Direct measurements of sea ice growth rates are used to validate the output of the sea ice growth model. It is shown that for sea ice formed during the 2011/2012 ice growth season at Barrow, Alaska, large changes in isotopic composition of the ocean waters were captured by the sea ice isotopic composition. Salinity anomalies in the ocean were also tracked by moored instruments. These data indicate episodic advection of meteoric water, having both lower salinity and lower oxygen isotopic composition, during the winter sea ice growth season. Such advection of meteoric water during winter is surprising, as no surface meltwater and no local river discharge should be occurring at this time of year in that area. How accurately changes in water masses as indicated by oxygen isotope composition can be reconstructed using oxygen isotope analysis of sea ice cores is addressed, along with methods/strategies that could be used to further optimize the results. The method described will be useful for winter detection of meteoric water presence in Arctic fast ice regions, which is important for climate studies in a rapidly changing Arctic. Land-fast sea ice effective fractionation coefficients were derived, with a range of +1.82‰ to +2.52‰. Those derived effective fractionation coefficients will be useful for future water mass component proportion calculations. In particular, the equations given can be used to inform choices made when engaging in end member determination for working out the component proportions of water masses.

Earth observations taken during STS-81 mission

NASA Image and Video Library

1997-01-13

STS081-715-004 (12-22 Jan. 1997) --- As photographed with a 70mm camera aboard the Space Shuttle Atlantis, this scene features the Volga River and Volgograd under snow. Contrast in brightness shows up many features in this near-vertical view of the great bend of the Volga River's dark, open strip of water, center. The Volga flows south into the view from top right, then southeast from the center to the bottom. Volgograd appears as the gray zone along the left (west) side of the open water. Presumably the ice-free part of the river opposite Volgograd relates to the slightly warmer water which is spilled from prominent, ice-covered Lake Volgograd (top right). The wide patterns of swirls, center to lower right, are numerous meander bends on the Volga's floodplain (up to 20 miles wide), highlighted by snow. The main course of the Volga is once again ice covered in this floodplain belt. The Volga-Don Canal can be seen leaving the river just south of the bend, exiting the view center left. This canal, with others in the Moscow region, allows barge traffic to move through the Russian heartland, from the Black Sea to the Baltic at Leningrad. The long parallel lines in threes and fours are lines of trees used as wind breaks. They stretch across Russia for hundreds of miles.

Climatic effects on ice-jam flooding of the Peace-Athabasca Delta

NASA Astrophysics Data System (ADS)

Beltaos, S.; Prowse, T.; Bonsal, B.; Mackay, R.; Romolo, L.; Pietroniro, A.; Toth, B.

2006-12-01

The Peace-Athabasca Delta (PAD) in northern Alberta is one of the world's largest inland freshwater deltas, home to large populations of waterfowl, muskrat, beaver, and free-ranging wood bison. In recent decades, a paucity of ice-jam flooding in the lower Peace River has resulted in prolonged dry periods and considerable reduction in the area covered by lakes and ponds that provide habitat for aquatic life in the PAD region. Building on previous work that has identified the salient hydro-climatic factors, the frequency of ice-jam floods is considered under present (1961-1990) and future (2070-2099) climatic conditions. The latter are determined using temperature and precipitation output from the Canadian Climate Centre's second-generation Global Climate Model (CGCM2) for two different greenhouse-gas/sulphate emission scenarios. The analysis indicates that the ice season is likely to be reduced by 2-4 weeks, while future ice covers would be slightly thinner than they are at present. More importantly, a large part of the Peace River basin is expected to experience frequent and sustained mid-winter thaws, leading to significant melt and depleted snowpacks in the spring. Using an empirical relationship between ice-jam flood occurrence and size of the spring snowpack, a severe reduction in the frequency of ice-jam flooding is predicted under both future-climate scenarios that were considered. In turn, this trend is likely to accelerate the loss of aquatic habitat in the PAD region. Implications for potential mitigation and adaptation strategies are discussed. Copyright

Understanding Nearshore Processes Of a Large Arctic Delta Using Combined Seabed Mapping, In Situ Observations, Remote Sensing and Modeling

NASA Astrophysics Data System (ADS)

Solomon, S. M.; Couture, N. J.; Forbes, D. L.; Hoque, A.; Jenner, K. A.; Lintern, G.; Mulligan, R. P.; Perrie, W. A.; Stevens, C. W.; Toulany, B.; Whalen, D.

2009-12-01

The Mackenzie River Delta and the adjacent continental shelf in the southeastern Beaufort Sea are known to host significant quantities of hydrocarbons. Recent environmental reviews of proposed hydrocarbon development have highlighted the need for a better understanding of the processes that control sediment transport and coastal stability. Over the past several years field surveys have been undertaken in winter, spring and summer to acquire data on seabed morphology, sediment properties, sea ice, river-ocean interaction and nearshore oceanography. These data are being used to improve conceptual models of nearshore processes and to develop and validate numerical models of waves, circulation and sediment transport. The timing and location of sediment erosion, transport and deposition is complex, driven by a combination of open water season storms and spring floods. Unlike temperate counterparts, the interaction between the Mackenzie River and the Beaufort Sea during spring freshet is mediated by the presence of ice cover. Increasing discharge exceeds the under-ice flow capacity leading to flooding of the ice surface, followed by vortex drainage through the ice and scour of the seabed below (“strudel” drainage and scour). During winter months, nearshore circulation slows beneath a thickening ice canopy. Recent surveys have shown that the low gradient inner shelf is composed of extensive shoals where ice freezes to the seabed and intervening zones which are slightly deeper than the ice is thick. The duration of ice contact with the bed determines the thermal characteristics of the seabed. Analysis of cores shows that the silts comprising the shoals are up to 6 m thick. The predominantly well sorted and cross-laminated nature of the silts at the top of the cores suggests an active delta front environment. Measurements of waves, currents, conductivity, temperature and sediment concentration during spring and late summer have been acquired. During moderate August storm events, waves attenuate rapidly inshore of the 3 m isobath. Entrainment of fine material and rapid flocculation due to the presence of brackish water may induce the transient formation of high density suspensions near the seabed which contributes to this rapid attenuation. The relatively poor performance of shallow water wave models (e.g. SWAN) in very shallow depths during storm simulations appears to be related to inaccurate formulations for wave attenuation in this environment.

Delta Evolution at Røde Elv, Disko Island, Greenland

NASA Astrophysics Data System (ADS)

Kroon, A.; Arngrimson, J.; Bendixen, M.; Sigsgaard, C.

2017-12-01

Ice, snow and freezing temperatures have a large impact on coastal morphodynamics in Arctic polar environments. A recent warming of the Arctic climate induces many changes along the arctic shorelines. Sea-levels are rising due to thermal expansion and due to an increased fresh water flux from the glaciers and land ice masses. At the same time, the ice coverage of the coastal waters reduces and the open water periods in summer extend. There is a strong seasonal variation with open waters and active rivers in summer and ice-covered coastal waters and inactive rivers in winter. Coastal processes by waves and tides are thus limited to the summer and early fall. Besides, there is also a strong daily variation in fluvial discharges due to the daily variations in glacier melt with maximum melt in the afternoon and minimum values at night. At the same time, the actual flux of the river to the coastal bay is influenced by the tidal phase. Low tides will enhance the transport to the delta front, while high tides will create stagnant waters over the delta plain. The delta of the Røde Elv is located in southwestern Disko Island in west Greenland. It has a relatively small (ca. 101 km2) and partly glaciated drainage basin (ca. 20%) and its sediments consist of a mixture of basaltic sands and gravels. The Røde Elv delta is located at the end of a pro-glacial and fluvial valley at about 20 km from the glacier. The shores of the delta are reworked by waves, predominantly from southwestern, southern (largest fetch, over 50 km), and southeastern directions. The environment has a micro- to meso- tidal range with a spring tidal range of 2.7 m. The morphologic changes on the delta over the last decades clearly showed a seaward extension of the delta and a periodic shift in the location of the main delta channel. In this presentation, we focus on quantification of water discharges and suspended sediment fluxes to the Røde Elv delta in western Greenland, and on the morphological evolution of the delta over the last decades. We highlight the variation of fluxes over different seasons under changing river discharges and tidal phases. We use field observations of river discharges and sediment fluxes at the lower part of the river close to the delta apex and estimate the wave activity on the delta front using wind and sea ice data and a numerical model computing wave-driven transport rates.

Spatial-temporal variations of seismic noise and their relation to wind, rivers, and basins in central Alaska

NASA Astrophysics Data System (ADS)

Smith, K.; Tape, C.; Bruton, C. P.; West, M. E.

2016-12-01

Continuous seismic recordings-or ambient noise-provide means for time-dependent monitoring of site conditions. Frequency-domain amplitude spectra of seismic recordings can be used to characterize time-dependent variations as a function of period (or frequency). Spatial variations can be characterized by using a set of stations across a large region. We analyze time-dependent ambient noise spectra from stations across central Alaska with three purposes. First, we are interested in monitoring the station performance and quality of a new array (FLATS) of 13 posthole seismometers near the Tanana River in Minto Flats. Second, we want to understand time-dependent threshold levels for earthquake detection: when noise is high, earthquake detections are low. Third, we are interested in identifying the effects of nature and Earth structure on seismic stations at different spatial-temporal scales. Our results show that seismic stations are sensitive to variations in wind speed and river flow. Correlations between wind speed and long-period (>10 seconds) seismic noise variations are probably due to tilt effects that have been previously documented. We identify a seismic signal at 10 Hz that is present only on stations close (<100 m) to the main channel of the Tanana river. The 10-Hz signal is strongly correlated with river gage height during summer and weakly correlated during the winter, when the river surface is covered in 1 m of ice. Spatial correlations among stations reveal large variations at shorter time scales (days); these could be due to weather anomalies. The amplitude of seismic noise at periods 2-10 s is strongly influenced by the thickness of sediment, which ranges from 0 m at bedrock sites to 6000 m at sites in the deepest part of Nenana basin. Our analysis allows us to better monitor the performance of temporary and permanent seismic stations, and to understand the physical causes of time-dependent noise variations in Alaska. Our findings show that seismic stations near rivers can potentially be used to monitor the flow of the river during summer and during ice-covered winter, raising the possibility for monitoring river ice break-up during April.

Geochemistry and mineralogy of late Quaternary loess in the upper Mississippi River valley, USA: Provenance and correlation with Laurentide Ice Sheet history

USGS Publications Warehouse

Muhs, Daniel; Bettis, E. Arthur; Skipp, Gary L.

2018-01-01

The midcontinent of North America contains some of the thickest and most extensive last-glacial loess deposits in the world, known as Peoria Loess. Peoria Loess of the upper Mississippi River valley region is thought to have had temporally varying glaciogenic sources resulting from inputs of sediment to the Mississippi River from different lobes of the Laurentide Ice Sheet. Here, we explore a new method of determining loess provenance using K/Rb and K/Ba values (in K-feldspars and micas) in loess from a number of different regions in North America. Results indicate that K/Rb and K/Ba values can distinguish loess originating from diverse geologic terrains in North America. Further, different loess bodies that are known to have had the same source sediments (using other criteria) have similar K/Rb and K/Ba values. We also studied three thick loess sections in the upper Mississippi River valley region. At each site, the primary composition of the loess changed over the course of the last glacial period, and K/Rb and K/Ba values parallel changes in carbonate mineral content and clay mineralogy. We thus confirm conclusions of earlier investigators that loess composition changed as a result of the shifting dominance of different lobes of the Laurentide Ice Sheet and the changing course of the Mississippi River. We conclude that K/Rb and K/Ba values are effective, robust, and rapid indicators of loess provenance that can be applied to many regions of the world.

Arctic Oases? - River Aufeis Maintain Perennial Groundwater Habitat in the Arctic

NASA Astrophysics Data System (ADS)

Huryn, A. D.; Gooseff, M. N.; Briggs, M. A.; Terry, N.; Kendrick, M.; Hendrickson, P. J.; Grunewald, E. D.

2017-12-01

Aufeis are massive accumulations of ice found along many arctic rivers, with aufeis on some Alaskan rivers covering 20+ km2 and attaining thicknesses of 5+ m. Although aufeis are prominent landscape features, understanding of their ecology is poor. We propose that aufeis function as summer oases by providing meltwater and nutrients to downstream habitats and winter oases due to insulating layers of ice that maintain below-ground freshwater habitat that would otherwise be frozen in regions of continuous permafrost. To gain information about the ecological roles of aufeis, we installed 50 1-m deep wells in a 1.5 km2aufeis field along the Kuparuk River, an arctic tundra river in Alaska. We assessed the predictions that aufeis provide perennially-unfrozen, below-ground habitat for a specialized invertebrate community while functioning as hot spots for nutrient regeneration. Surface geophysical measurements made during the time of maximum ice thickness in 2017 indicated most of the Kuparuk feature was underlain by several meters of shallow frozen cobbles that were further underlain by a 10 m thick+ zone of thawed material. Ground penetrating radar and surface nuclear magnetic resonance data indicated several spatially-discrete thawed preferential flow zones through the shallow frozen sediment layer that may result from groundwater upwelling observed flowing through fractures in the icepack. Freshwater invertebrates sampled from the wells represent a rich community consisting of flatworms, annelids, copepods, ostracods, chironomids (Krenosmittia, Trichotanypus) and stoneflies. Although the potential for below-ground NH4+ and NO3-regeneration was indicated, analyses were complicated bya surprisingly strong and dynamic coupling of surface and below-ground water.

Geochemistry and mineralogy of late Quaternary loess in the upper Mississippi River valley, USA: Provenance and correlation with Laurentide Ice Sheet history

NASA Astrophysics Data System (ADS)

Muhs, Daniel R.; Bettis, E. Arthur; Skipp, Gary L.

2018-05-01

The midcontinent of North America contains some of the thickest and most extensive last-glacial loess deposits in the world, known as Peoria Loess. Peoria Loess of the upper Mississippi River valley region is thought to have had temporally varying glaciogenic sources resulting from inputs of sediment to the Mississippi River from different lobes of the Laurentide Ice Sheet. Here, we explore a new method of determining loess provenance using K/Rb and K/Ba values (in K-feldspars and micas) in loess from a number of different regions in North America. Results indicate that K/Rb and K/Ba values can distinguish loess originating from diverse geologic terrains in North America. Further, different loess bodies that are known to have had the same source sediments (using other criteria) have similar K/Rb and K/Ba values. We also studied three thick loess sections in the upper Mississippi River valley region. At each site, the primary composition of the loess changed over the course of the last glacial period, and K/Rb and K/Ba values parallel changes in carbonate mineral content and clay mineralogy. We thus confirm conclusions of earlier investigators that loess composition changed as a result of the shifting dominance of different lobes of the Laurentide Ice Sheet and the changing course of the Mississippi River. We conclude that K/Rb and K/Ba values are effective, robust, and rapid indicators of loess provenance that can be applied to many regions of the world.

Dynamic Hydrological Discharge Modelling for Fully Coupled Paleoclimate Runs of the Last Glacial Cycle

NASA Astrophysics Data System (ADS)

Riddick, Thomas; Brovkin, Victor; Hagemann, Stefan; Mikolajewicz, Uwe

2017-04-01

The continually evolving large ice sheets present in the Northern Hemisphere during the last glacial cycle caused significant changes to river pathways both through directly blocking rivers and through glacial isostatic adjustment. These river pathway changes are believed to of had a significant impact on the evolution of ocean circulation through changing the pattern of fresh water discharge into the oceans. A fully coupled ESM simulation of the last glacial cycle thus requires a hydrological discharge model that uses a set of river pathways that evolve with the earth's changing orography while being able to reproduce the known present-day river network given the present-day orography. Here we present a method for dynamically modelling hydrological discharge that meets such requirements by applying relative manual corrections to an evolving fine scale orography (accounting for the changing ice sheets and isostatic rebound) each time the river directions are recalculated. The corrected orography thus produced is then used to create a set of fine scale river pathways and these are then upscaled to a course scale. An existing present-day hydrological discharge model within the JSBACH3 land surface model is run using the course scale river pathways generated. This method will be used in fully coupled paleoclimate runs made using MPI-ESM1 as part of the PalMod project. Tests show this procedure reproduces the known present-day river network to a sufficient degree of accuracy.

South Greenland, North Atlantic Ocean

NASA Technical Reports Server (NTRS)

1992-01-01

This spectacular north looking view of south Greenland (62.0N, 46.0W) shows numerous indentations along the coastline, many of which contain small settlements. These indentations are fiords carved by glaciers of the last ice age. Even today, ice in the center of Greenland is as much as 10,000 ft. thick and great rivers of ice continuously flow toward the sea, where they melt or break off as icebergs - some of which may be seen floating offshore.

South Greenland, North Atlantic Ocean

NASA Image and Video Library

1992-04-02

This spectacular north looking view of south Greenland (62.0N, 46.0W) shows numerous indentations along the coastline, many of which contain small settlements. These indentations are fiords carved by glaciers of the last ice age. Even today, ice in the center of Greenland is as much as 10,000 ft. thick and great rivers of ice continuously flow toward the sea, where they melt or break off as icebergs - some of which may be seen floating offshore.

Arctic and subarctic environmental analyses utilizing ERTS-1 imagery

NASA Technical Reports Server (NTRS)

Anderson, D. M. (Principal Investigator); Mckim, H. L.; Gatto, L. W.; Haugen, R. K.; Crowder, W. K.; Slaughter, C. W.; Marlar, T. L.

1974-01-01

The author has identified the following significant results. ERTS-1 imagery provides a means of distinguishing and monitoring estuarine surface water circulation patterns and changes in the relative sediment load of discharging rivers on a regional basis. Physical boundaries mapped from ERTS-1 imagery in combination with ground truth obtained from existing small scale maps and other sources resulted in improved and more detailed maps of permafrost terrain and vegetation for the same area. Snowpack cover within a research watershed has been analyzed and compared to ground data. Large river icings along the proposed Alaska pipeline route from Prudhoe Bay to the Brooks Range have been monitored. Sea ice deformation and drift northeast of Point Barrow, Alaska have been measured during a four day period in March and shore-fast ice accumulation and ablation along the west coast of Alaska have been mapped for the spring and early summer seasons.

Tijuana River Flood Control Project, San Diego County, California.

DTIC Science & Technology

1976-05-20

vulgare Fragrant everlasting Gnaphalium beneolens White hoarhound Marrubium vulgere Hottentot-f ig Mesembryanthemum edule ANNUALS Tumbleweed Amaranthus a...scoparium California box-thorn Lycium californicum See fig Mesembryanthemum chilense Ice plant Mesembryanthemum crystallinum Hottentot fig... Mesembryanthemum edule Little ice plant Mesembryanthemum nodiflorum Coastal prickly pear Opuntia occidentalis San Diego cholla Opuntia serpentia Salt marsh

Open-water and under-ice seasonal variations in trace element content and physicochemical associations in fluvial bed sediment.

PubMed

Doig, Lorne E; Carr, Meghan K; Meissner, Anna G N; Jardine, Tim D; Jones, Paul D; Bharadwaj, Lalita; Lindenschmidt, Karl-Erich

2017-11-01

Across the circumpolar world, intensive anthropogenic activities in the southern reaches of many large, northward-flowing rivers can cause sediment contamination in the downstream depositional environment. The influence of ice cover on concentrations of inorganic contaminants in bed sediment (i.e., sediment quality) is unknown in these rivers, where winter is the dominant season. A geomorphic response unit approach was used to select hydraulically diverse sampling sites across a northern test-case system, the Slave River and delta (Northwest Territories, Canada). Surface sediment samples (top 1 cm) were collected from 6 predefined geomorphic response units (12 sites) to assess the relationships between bed sediment physicochemistry (particle size distribution and total organic carbon content) and trace element content (mercury and 18 other trace elements) during open-water conditions. A subset of sites was resampled under-ice to assess the influence of season on these relationships and on total trace element content. Concentrations of the majority of trace elements were strongly correlated with percent fines and proxies for grain size (aluminum and iron), with similar trace element grain size/grain size proxy relationships between seasons. However, finer materials were deposited under ice with associated increases in sediment total organic carbon content and the concentrations of most trace elements investigated. The geomorphic response unit approach was effective at identifying diverse hydrological environments for sampling prior to field operations. Our data demonstrate the need for under-ice sampling to confirm year-round consistency in trace element-geochemical relationships in fluvial systems and to define the upper extremes of these relationships. Whether contaminated or not, under-ice bed sediment can represent a "worst-case" scenario in terms of trace element concentrations and exposure for sediment-associated organisms in northern fluvial systems. Environ Toxicol Chem 2017;36:2916-2924. © 2017 SETAC. © 2017 SETAC.

Unraveling of permafrost hydrological variabilities on Central Qinghai-Tibet Plateau using stable isotopic technique.

PubMed

Yang, Yuzhong; Wu, Qingbai; Hou, Yandong; Zhang, Zhongqiong; Zhan, Jing; Gao, Siru; Jin, Huijun

2017-12-15

Permafrost degradation on the Qinghai-Tibet Plateau (QTP) will substantially alter the surface runoff discharge and generation, which changes the recharge processes and influences the hydrological cycle on the QTP. Hydrological connections between different water bodies and the influence of thawing permafrost (ground ice) are not well understood on the QTP. This study applied water stable isotopic method to investigate the permafrost hydrological variabilities in Beiluhe Basin (BLB) on Central QTP. Isotopic variations of precipitation, river flow, thermokarst lake, and near-surface ground ice were identified to figure out the moisture source of them, and to elaborate the hydrological connections in permafrost region. Results suggested that isotopic seasonalities in precipitation is evident, it is showing more positive values in summer seasons, and negative values in winter seasons. Stable isotopes of river flow are mainly distributed in the range of precipitation which is indicative of important replenishment from precipitation. δ 18 O, δD of thermokarst lakes are more positive than precipitation, indicating of basin-scale evaporation of lake water. Comparison of δ I values in different water bodies shows that hydrology of thermokarst lakes was related to thawing of permafrost (ground ice) and precipitation. Near-surface ground ice in BLB exhibits different isotopic characteristics, and generates a special δD-δ 18 O relationship (freezing line): δD=5.81δ 18 O-23.02, which reflects typical freezing of liquid water. From isotopic analysis, it is inferred that near-surface ground ice was mainly recharged by precipitation and active layer water. Stable isotopic and conceptual model is suggestive of striking hydrological connections between precipitation, river flow, thermokarst lake, and ground ice under degrading permafrost. This research provides fundamental comprehensions into the hydrological processes in permafrost regions on QTP, which should be considered in investigating the influence of thawing permafrost on the hydrological cycle on QTP. Copyright © 2017 Elsevier B.V. All rights reserved.

δ18O and δD variations in Holocene massive ice in the Sabettayakha river mouth, northern Yamal Peninsula

NASA Astrophysics Data System (ADS)

Vasil'chuk, Yu. K.; Podborny, Ye. Ye.; Budantseva, N. A.; Vasil'chuk, A. C.; Sullina, A. N.; Chizhova, Ju. N.

2016-10-01

The conditions of formation of massive ice near the South Tambey gas-condensate field in northern Yamal Peninsula are studied. It is shown that massive ice bodies up to 4.5 m thick occur in the Holocene deposits of the high laida and the first terrace. Therefore, they cannot be the remains of glaciers; they are ground ice formations. All three types of massive ice have quite various isotopic compositions: the values of δD range from-107 to-199.7, and δ18O from-15.7 to-26.48‰. Such a significant differentiation in isotopic composition is a result of cryogenic fractionation in a freezing water-saturated sediment. The most negative isotope values are even lower in this Holocene massive ice than in the Late Pleistocene ice-wedge ice of Yamal Peninsula.

Fluvial responses to the Weichselian ice sheet advances and retreats: implications for understanding river paleohydrology and pattern changes in Central Poland

NASA Astrophysics Data System (ADS)

Weckwerth, Piotr

2018-06-01

The evolution of the fluvial systems during the Weichselian Pleniglacial in the Toruń Basin (Central Poland) was investigated through sedimentological investigation and paleohydraulic analysis. Within the basin, three fluvial cycles deposited after successive phases of the ice advance which took place 50, 28 and 20 ka ago. Successions of four fluvial lithotypes characterize each fluvial formation, that are related to the paleoenvironmental changes (e.g., climate instability and changes in the river regime) which affected the channel hydraulics and morphology. The successions comprise river-style metamorphosis between high-energy sand-bed meandering rivers (lithotype M1), high-energy sand-bed braided rivers (lithotype B1), and medium-energy sand-bed braided rivers with either unit bars (lithotype B2) or compound bars (lithotype B3) reflects the maturity stage of sand-bed-braided river evolution in the basin. The assessment of the fluvial sedimentary environments enabled the construction of a quantitative model of the changes in the river channel pattern in relation to the climate oscillation. Both the paleohydrological controls and their sedimentary consequences are discussed in the article. Lithotypes M1 and B1 represent riverbed modeled under supercritical flow condition. Deposition of lithotype B2 corresponded to the river channel pattern transformation and was manifested by decreasing flow velocity (energy losses associated with bedform roughness and with the transportation of coarser particles). The flow velocity was generally greater in rivers of lithotype B3 and energy of sedimentary environment was more stable than during the deposition of lithotype B2.

Permafrost Mobilization from the Watershed to the Colville River Delta: Evidence from Biomarkers and 14C Ramped Pyrolysis

NASA Astrophysics Data System (ADS)

Zhang, X.; Bianchi, T. S.; Cui, X.; Rosenheim, B. E.; Ping, C. L.; Kanevskiy, M. Z.; Hanna, A. M.; Allison, M. A.

2016-12-01

As temperatures in the Arctic rise abnormally fast, permafrost in the region is vulnerable to extensive thawing. This could release previously frozen organic carbon (OC) into the contemporary carbon cycle, giving a positive feedback on global warming. Recent research has found the presence of particulate permafrost in rivers, deltas, and continental shelves in the Arctic, but little direct evidence exists on the mechanism of transportation of previously frozen soils from watershed to the coast. The Colville River in northern Alaska is the largest North American Arctic River with a continuous permafrost within its watershed. Previous work has found evidence for the deposition of previously frozen soils in the Colville River delta (Schreiner et al., 2014). Here, we compared the bulk organic carbon thermal properties, ages of soils and river and delta sediments from the Colville River drainage system using 14C Ramped Pyrolysis and chemical biomarkers. Our data show that deep permafrost soils as well as river and delta sediments had similar pyrograms and biomarker signatures, reflecting transport of soils from watershed to the delta. Surface soil had pyrograms indicative of less stable (more biodegradable) OC than deeper soil horizons. Similarity in pyrograms of deep soils and river sediment indicated the limited contribution of surface soils to riverine particulate OC inputs. Sediments in the delta showed inputs of yedoma (ice-rich syngenetic permafrost with large ice wedges) from the watershed sources (e.g., river bank erosion) in addition to peat inputs, that were largely from coastal erosion.

Quaternary geologic map of the Havre 1° x 2° quadrangle

USGS Publications Warehouse

Compilations by Fullerton, David S.; Colton, Roger B.; Bush, Charles A.

2012-01-01

The Havre quadrangle encompasses approximately 16,084 km2 (6,210 mi2). The northern boundary is the Montana/Saskatchewan (U.S./Canada) boundary. The quadrangle is in the Northern Plains physiographic province and it includes parts of the Bearpaw Mountains, the Little Rocky Mountains, and the Boundary Plateau. The primary river is the Milk River. The ancestral Missouri River was diverted south of the Bearpaw Mountains by a Laurentide ice sheet. The fill in the buried ancestral valley at and southwest of Havre contains a complex stratigraphy of fluvial, glaciofluvial, ice-contact, glacial, lacustrine, and eolian deposits. The old valley east of Havre now is occupied by the Milk River. The map units are surficial deposits and materials, not landforms. Deposits that comprise some constructional landforms (e.g., ground-moraine deposits, end-moraine deposits, stagnation-moraine deposits, all composed of till) are distinguished for purposes of reconstruction of glacial history. Surficial deposits and materials are assigned to 24 map units on the basis of genesis, age, lithology or composition, texture or particle size, and other physical, chemical, and engineering characteristics. It is not a map of soils that are recognized in engineering geology, or of substrata or parent materials in which pedologic or agronomic soils are formed. Glaciotectonic (ice-thrust) structures and deposits are mapped separately, represented by a symbol. On the glaciated plains and on the Boundary Plateau the surficial deposits are glacial, ice-contact, glaciofluvial, catastrophic flood, alluvial, lacustrine, eolian, and colluvial deposits. In the Bearpaw Mountains and Little Rocky Mountains beyond the limit of Quaternary glaciation they are fluvial, colluvial, and mass-wasting deposits and residual materials. Tills of late Wisconsin and Illinoian ages are represented by map units. Tills of two pre-Illinoian glaciations are not mapped but are widespread in the subsurface and are identified in stratigraphic sections. Thirteen stratigraphic sections document a complex glacial and interglacial history in the quadrangle. Pliocene continental glaciation possibly is represented by erratic blocks of garnet gneiss and pegmatite from the Canadian Shield, perched high on drainage divides in the western Bearpaw Mountains. Glacial striations on bedrock, two boulder trains, and linear ice-molded landforms (primarily drumlins) indicate the possible presence of an east-southeast flowing ice stream in the Havre glacial lobe during late Wisconsin glaciation.

Quantifying landscape change in an arctic coastal lowland using repeat airborne LiDAR

USGS Publications Warehouse

Jones, Benjamin M.; Stoker, Jason M.; Gibbs, Ann E.; Grosse, Guido; Romanovsky, Vladimir E.; Douglas, Thomas A.; Kinsman, Nichole E.M.; Richmond, Bruce M.

2013-01-01

Increases in air, permafrost, and sea surface temperature, loss of sea ice, the potential for increased wave energy, and higher river discharge may all be interacting to escalate erosion of arctic coastal lowland landscapes. Here we use airborne light detection and ranging (LiDAR) data acquired in 2006 and 2010 to detect landscape change in a 100 km2 study area on the Beaufort Sea coastal plain of northern Alaska. We detected statistically significant change (99% confidence interval), defined as contiguous areas (>10 m2) that had changed in height by at least 0.55 m, in 0.3% of the study region. Erosional features indicative of ice-rich permafrost degradation were associated with ice-bonded coastal, river, and lake bluffs, frost mounds, ice wedges, and thermo-erosional gullies. These features accounted for about half of the area where vertical change was detected. Inferred thermo-denudation and thermo-abrasion of coastal and river bluffs likely accounted for the dominant permafrost-related degradational processes with respect to area (42%) and volume (51%). More than 300 thermokarst pits significantly subsided during the study period, likely as a result of storm surge flooding of low-lying tundra (<1.4 m asl) as well as the lasting impact of warm summers in the late-1980s and mid-1990s. Our results indicate that repeat airborne LiDAR can be used to detect landscape change in arctic coastal lowland regions at large spatial scales over sub-decadal time periods.

Investigating hydrologic controls on glacier velocity using 222Rn as a proxy for variable subglacial pressure

NASA Astrophysics Data System (ADS)

Linhoff, B.; Charette, M. A.; Tedstone, A. J.; Ingle, A.; Bartholomew, I.; Cowton, T.; Butler, C. E.; Sole, A. J.; Nienow, P. W.; Wadham, J. L.; Chandler, D.

2013-12-01

Each summer, meltwater forms on the surface of the Greenland Ice Sheet and travels through cracks and moulins to the ice-bed. There, hydraulic pressure in cavities and channels controls glacial sliding; coincident with the highest hydraulic pressures are the fastest annual glacial speeds. Meltwater pathways at the ice-bed undergo a seasonal evolution from high-pressure, inefficient linked-cavity systems at the onset of spring melt to low-pressure, high-capacity channelized systems by midsummer. Radon-222 (t1/2 = 3.8 days) is a promising new tool for glaciology (Bhatia et al., 2011) as it is injected into meltwater during interaction with sediment and rock through the radioactive decay of naturally occurring 226Ra. Therefore in proglacial rivers, 222Rn can be assumed to trace fluxes of subglacial groundwater or meltwater transiently stored at the ice-bed. Radon-222 was quantified in the proglacial river of Leverett Glacier, a large outlet glacier of the Greenland Ice Sheet, during the summers of 2011 (May 8th - August 10th) and 2012 (May 12th - August 1st). Continuous (hourly) measurements were made using a RAD-7 (Durridge Inc.) with gas-permeable tubing in place of the air-water equilibrator. We estimated englacial meltwater storage as the difference between proglacial river discharge and meltwater inputs, calculated from a positive degree-day melt model based on temperature sensors on the ice surface and MODIS satellite imagery to determine the timing and size of supraglacial lake drainage events. Periods of high glacial velocity displayed strong subdiurnal covariations with 222Rn. We hypothesize that this is the result of increasing englacial meltwater storage, channel pressurization and 222Rn tracing groundwater fluxes. When pressure is rising in channels, meltwater is driven distally into adjacent linked cavity networks where it is temporarily stored while channel pressures are centrifugal. During these periods, meltwater traveling though channels likely has minimal interaction with the bed and therefore accumulates negligible amounts of 222Rn. Instead, during periods of channel pressurization 222Rn likely traces the flux of groundwater. As groundwater discharge to the ice margin is controlled by pressure at the ice-bed, periods of increasing channel pressurization and englacial storage will result in groundwater fluxes proportional to hydraulic pressure and, consequently, ice velocity. In support of this hypothesis, we observed the largest fluxes of 222Rn in the proglacial river during multi-day periods of low glacial velocity. These observations are consistent with channel depressurization and drainage of meltwater stored in linked cavity systems. Bhatia, M.P., Das, S.B., Kujawinski, E.B., Henderson, P., Burke, A., Charette, M.A., 2011. Seasonal evolution of water contributions to discharge from a Greenland outlet glacier: insight from a new isotope-mixing model. J Glaciol 57, 929-941.

A Model for the Formation and Melting of Ice on Surface Waters.

NASA Astrophysics Data System (ADS)

de Bruin, H. A. R.; Wessels, H. R. A.

1988-02-01

Ice covers have an important influence on the hydrology of surface waters. The growth of ice layer on stationary waters, such as lakes or canals, depends primarily on meteorological parameters like temperature and humidity of the air, windspeed and radiation balance. The more complicated ice formation in rapidly flowing rivers is not considered in this study. A model is described that simulates ice growth and melting utilizing observed or forecast weather data. The model includes situations with a snow cover. Special attention is given to the optimal estimation of the net radiation and to the role of the stability of the near-surface air. Since a major practical application in the Netherlands is the use of frozen waters for recreation skating, the model is extended to include artificial ice tracks.

Evaluation of Dam Decommissioning in an Ice-Affected River: Case Study

DTIC Science & Technology

2007-09-01

Abdul-Mohsen 2005 and Kuby et al. 2005). Conyngham et al. (2006) provide an overview of the ecological and engi- neering aspects of dam decommissioning...2007) CRREL Ice Jam Database (http://www.crrel.usace.army.mil/ierd/ijdb/), accessed March 2007. Kuby , M.J., W.F. Fagan, C.S. ReVelle, W.L. Graf (2005

Impacts of Colville River dynamics on river navigability near Nuiqsut, Alaska: 1955-present

NASA Astrophysics Data System (ADS)

Whitley, M. A.; Panda, S. K.; Prakash, A.; Brinkman, T. J.

2016-12-01

Climate-driven changes in river systems are challenging access to ecosystem services such as access to traditional hunting grounds and other subsistence food sources on the North Slope of Alaska. This work studies the dynamics of the Colville River and assesses the impacts on traditional harvest practices and subsistence travel of the Native community of Nuiqsut. Recent reports from Nuiqsut residents indicate accelerated changes in the environment, limiting river travel and their ability to harvest subsistence food. This study explores how channel migration, gravel bars, and bank erosion have evolved since the 1950s, and their impact on water depth and navigability. In an area of ice-rich permafrost, warmer summer temperatures exacerbate lateral bank erosion, resulting in river siltation. The study focuses on selected key areas south of Nuiqsut that have shown significant change in river geomorphology. Since 1955, some areas proximate to ice wedge exposures show channel migration in excess of 1 km. Panchromatic aerial photography acquired by US Geological Surveys in the mid 1950s, color infrared aerial photography from 1979 and 1982 acquired by the Alaska High Altitude Photography (AHAP) mission, and high resolution satellite images from Digital Globe, Inc. were used in this study. We mapped water, vegetation, and gravel/non-vegetated classes to identify risk areas for river navigability. River bathymetry was also mapped using a multispectral ratio-based water depth retrieval algorithm to identify problem sites for boat travel. Remote sensing products and analyses were validated with field data for mapping risk areas along the river. This study has the potential to be implemented on a larger scale for predictive mapping to aid river navigation. Findings from this study will provide insight whether recent changes are anomalies, or if they are part of a directional trend that will require local adaptation.

Late Pleistocene eolian features in southeastern Maryland and Chesapeake Bay region indicate strong WNW-NW winds accompanied growth of the Laurentide Ice Sheet

USGS Publications Warehouse

Markewich, H.W.; Litwin, R.J.; Pavich, M.J.; Brook, G.A.

2009-01-01

Inactive parabolic dunes are present in southeastern Maryland, USA, along the east bank of the Potomac River. More elongate and finer-grained eolian deposits and paha-like ridges characterize the Potomac River-Patuxent River upland and the west side of Chesapeake Bay. These ridges are streamlined erosional features, veneered with eolian sediment and interspersed with dunes in the low-relief headwaters of Potomac- and Patuxent-river tributaries. Axis data for the dunes and ridges indicate formation by WNW-NW winds. Optically stimulated luminescence and radiocarbon age data suggest dune formation from ??? 33-15??ka, agreeing with the 30-13??ka ages Denny, C.S., Owens, J.P., Sirkin, L., Rubin, M., 1979. The Parsonburg Sand in the central Delmarva Peninsula, Maryland and Delaware. U.S. Geol. Surv. Prof. Pap. 1067-B, 16??pp. suggested for eolian deposits east of Chesapeake Bay. Age range and paleowind direction(s) for eolian features in the Bay region approximate those for late Wisconsin loess in the North American midcontinent. Formation of midcontinent loess and Bay-region eolian features was coeval with rapid growth of the Laurentide Ice Sheet and strong cooling episodes (??18O minima) evident in Greenland ice cores. Age and paleowind-direction coincidence, for eolian features in the midcontinent and Bay region, indicates strong mid-latitude WNW-NW winds for several hundred kilometers south of the Laurentide glacial terminus that were oblique to previously simulated anticyclonic winds for the last glacial maximum.

Influence of the Yukon River on the Bering Sea

NASA Technical Reports Server (NTRS)

Dean, K.; Mcroy, C. P.

1986-01-01

The purpose is to use satellite data to study relationships between discharge of the Yukon River to currents and biologic productivity in the northern Bering Sea. Amended specific objectives are: to develop thermal, sediment and chlorophyll surface maps using thematic mapping (TM) data of the discharge of the Yukon River and the Alaska Coastal Current during the ice free season; to develop a historical model of the distribution of the Yukon River discharge and the Alaska Coastal Current using LANDSAT multispectral scanner (MMS) and NOAA satellite imagery; and to use high resolution TM data to define the surface dynamics of the front between the Alaska Coastal Current and the Bering Shelf/Anadyr Current. LANDSAT MSS and TM, and Advanced Very High Resolution Radiometer (AVHRR) data were recorded during the 1985 ice-free period. The satellite data coincided with shipboard measurements acquired by Inner Self Transfer and Recycling scientists. Circumstances were such, that on July 5 and July 22, all three sensors recorded data that has been registered to a common map projection and map base, then contrast stretched, color composited, and density sliced.

Quantifying present and future glacier melt-water contribution to runoff in a Central Himalayan river basin

NASA Astrophysics Data System (ADS)

Prasch, M.; Mauser, W.; Weber, M.

2012-10-01

Water supply of most lowland cultures heavily depends on rain and melt-water from the upstream mountains. Especially melt-water release of alpine mountain ranges is usually attributed a pivotal role for the water supply of large downstream regions. Water scarcity is assumed as consequence of glacier shrinkage and possible disappearance due to Global Climate Change, particular for large parts of Central and South East Asia. In this paper, the application and validation of a coupled modeling approach with Regional Climate Model outputs and a process-oriented glacier and hydrological model is presented for a Central Himalayan river basin despite scarce data availability. Current and possible future contributions of ice-melt to runoff along the river network are spatially explicitly shown. Its role among the other water balance components is presented. Although glaciers have retreated and will continue to retreat according to the chosen climate scenarios, water availability is and will be primarily determined by monsoon precipitation and snow-melt. Ice-melt from glaciers is and will be a minor runoff component in summer monsoon-dominated Himalayan river basins.

Remote sensing of snow and ice

NASA Technical Reports Server (NTRS)

Rango, A.

1979-01-01

This paper reviews remote sensing of snow and ice, techniques for improved monitoring, and incorporation of the new data into forecasting and management systems. The snowcover interpretation of visible and infrared data from satellites, automated digital methods, radiative transfer modeling to calculate the solar reflectance of snow, and models using snowcover input data and elevation zones for calculating snowmelt are discussed. The use of visible and near infrared techniques for inferring snow properties, microwave monitoring of snowpack characteristics, use of Landsat images for collecting glacier data, monitoring of river ice with visible imagery from NOAA satellites, use of sequential imagery for tracking ice flow movement, and microwave studies of sea ice are described. Applications of snow and ice research to commercial use are examined, and it is concluded that a major problem to be solved is characterization of snow and ice in nature, since assigning of the correct properties to a real system to be modeled has been difficult.

Laurentide ice sheet meltwater routing along the Iro-Mohawk River, eastern New York, USA

NASA Astrophysics Data System (ADS)

Porreca, Charles; Briner, Jason P.; Kozlowski, Andrew

2018-02-01

The rerouting of meltwater as the configuration of ice sheets evolved during the last deglaciation is thought to have led to some of the most significant perturbations to the climate system in the late Quaternary. However, the complex pattern of ice sheet meltwater drainage off the continents, and the timing of rerouting events, remains to be fully resolved. As the Laurentide Ice Sheet (LIS) retreated north of the Adirondack Uplands of northeastern New York State during the last deglaciation, a large proglacial lake, Lake Iroquois, found a lower outlet that resulted in a significant flood event. This meltwater rerouting event, from outflow via the Iro-Mohawk River valley (southern Adirondack Mountains) to the spillway at Covey Hill (northeastern Adirondack Mountains), is hypothesized to have taken place 13.2 ka and disturbed meridional circulation in the North Atlantic Ocean. However, the timing of the rerouting event is not certain because the event has not been directly dated. With improving the history of Lake Iroquois drainage in mind, we obtained cosmogenic 10Be exposure ages on a strath terrace on Moss Island, along the Iro-Mohawk River spillway. We hypothesize that Moss Island's strath terrace became abandoned during the rerouting event. Six 10Be ages from the strath surface average 14.8 ± 1.3 ka, which predates the previously published bracketing radiocarbon ages of 13.2 ka. Several possibilities for the discrepancy exist: (1) the 10Be age accurately represents the timing of a decrease in discharge through the Iro-Mohawk River spillway; (2) the age is influenced by inheritance. The 10Be ages from glacially sculpted surfaces on Moss Island above the strath terrace predate the deglaciation of the site by 5 to 35 ky; and (3) the abandonment of the Moss Island strath terrace relates to knickpoint migration and not the final abandonment of the Iro-Mohawk River as the Lake Iroquois spillway. Further study and application of cosmogenic 10Be exposure dating in the region may lead to tighter chronologic constraints of meltwater history of the LIS.

Field observations of slush ice generated during freeze-up in arctic coastal waters

USGS Publications Warehouse

Reimnitz, E.; Kempema, E.W.

1987-01-01

In some years, large volumes of slush ice charged with sediment are generated from frazil crystals in the shallow Beaufort Sea during strong storms at the time of freeze-up. Such events terminate the navigation season, and because of accompanying hostile conditions, little is known about the processes acting. The water-saturated slush ice, which may reach a thickness of 4 m, exists for only a few days before freezing from the surface downward arrests further wave motion or pancake ice forms. Movements of small vessels and divers in the slush ice occurs only in phase with passing waves, producing compression and rarefaction, and internal pressure pulses. Where in contact with the seafloor, the agitated slush ice moves cobble-size material, generates large sediment ripples, and may possibly produce a flat rampart observed on the arctic shoreface in some years. Processes charging the slush ice with as much as 1000 m3 km-2 of sediment remain uncertain, but our field observations rule out previously proposed filtration from turbid waters as a likely mechanism. Sedimentary particles apparently are only trapped in the interstices of the slush ice rather than being held by adhesion, since wave-related internal pressure oscillations result in downward particle movement and cleansing of the slush ice. This loss of sediment explains the typical downward increase in sediment concentration in that part of the fast-ice canopy composed largely of frazil ice. The congealing slush ice in coastal water does not become fast ice until grounded ridges are formed in the stamukhi zone, one to two months after freeze-up begins. During this period of new-ice mobility, long-range sediment transport occurs. The sediment load held by the fast-ice canopy in the area between the Colville and Sagavanirktok River deltas in the winter of 1978-1979 was 16 times larger than the yearly river input to the same area. This sediment most likely was rafted from Canada, more than 400 km to the east, during a brief time period in the previous fall. Ocean turbulence is greatly reduced while the congealing slush ice drifts about. Therefore, new ice then forming in intervening open-water areas is clean. These events explain the patchy appearance of the fast ice after the summer snowmelt. More work on the important phenomena reported here is needed to close a major gap in the knowledge of the arctic marine environment. ?? 1987.

Effects of the earthquake of March 27, 1964 in the Copper River Basin area, Alaska: Chapter E in The Alaska earthquake, March 27, 1964: regional effects

USGS Publications Warehouse

Ferrians, Oscar J.

1966-01-01

The Copper River Basin area is in south-central Alaska and covers 17,800 square miles. It includes most of the Copper River Basin and parts of the surrounding Alaska Range and the Talkeetna, Chugach, and Wrangell Mountains. On March 27, 1964, shortly after 5:36 p.m. Alaska standard time, a great earthquake having a Richter magnitude of about 8.5 struck south-central Alaska. Computations by the U.S. Coast and Geodetic Survey place the epicenter of the main shock at lat 61.1° N. and long 147.7° W., and the hypocenter, or actual point of origin, from 20 to 50 kilometers below the surface. The epicenter is near the western shore of Unakwik Inlet in northern Prince William Sound; it is 30 miles from the closest point within the area of study and 180 miles from the farthest point. Releveling data obtained in 1964 after the earthquake indicates that broad areas of south-central Alaska were warped by uplift and subsidence. The configuration of these areas generally parallels the trend of the major tectonic elements of the region. Presumably a large part of this change took place during and immediately after the 1964 earthquake. The water level in several wells in the area lowered appreciably, and the water in many became turbid; generally, however, within a few days after the earthquake the water level returned to normal and the suspended sediment settled out. Newspaper reports that the Copper River was completely dammed and Tazlina Lake drained proved erroneous. The ice on most lakes was cracked, especially around the margins of the lakes where floating ice broke free from the ice frozen to the shore. Ice on Tazlina, Klutina, and Tonsina Lakes was intensely fractured by waves generated by sublacustrine landslides off the fronts of deltas. These waves stranded large blocks of ice above water level along the shores. River ice was generally cracked in the southern half of the area and was locally cracked in the northern half. In the area of study, the majority of the ground cracks occurred within a radius of 100 miles from the epicenter of the earthquake. Ground cracks formed in flood plains of rivers, in deltas, and along the toes of alluvial fans. They also occurred locally in low terraces adjacent to flood plains, in highway and other fill material, along the margins of lakes, along the faces of steep slopes of river bluffs and hillsides, and in areas cleared of vegetation for several years. The ground cracks were restricted to areas underlain by unconsolidated deposits where one or more of the following conditions existed: (1) permafrost was absent or deep lying, (2) the ground-water table was near the surface, (3) bedrock was relatively deep lying, and (4) slopes were steep. Because the earthquake occurred in March, seasonal frost was present throughout the area. Despite the diversity of local conditions, the origin of most of the ground cracks can be explained by the following mechanisms: (1) lateral extension, caused by materials moving toward an unconfined face such as a lakeshore, river bluff, hillside, or terrace escarpment; (2) horizontal compaction, caused by repeated alternate compression and dilation (in the horizontal direction) of materials in flat-lying areas where there are no unconfined faces; (3) differential vertical compaction, caused by the shaking of materials that vary laterally in thickness or character; and (4) combinations of the above. Snowslides, avalanches, and rockslides were restricted to the mountainous areas surrounding the Copper River Basin. They were especially numerous in the Chugach Mountains which are closest to the epicenter of the earthquake. The large amount of snow and rock debris that has cascaded onto the icefield and glaciers of these mountains, and, probably even more important, the overall disturbance to the ice field will affect the regimen of the glaciers. Most of the damage to manmade structures occurred in the southern half of the area, and, primarily because of the sparsity of population and manmade structures, property damage was not great and no lives were lost.

Map of Western Copper River Basin, Alaska, Showing Lake Sediments and Shorelines, Glacial Moraines, and Location of Stratigraphic Sections and Radiocarbon-Dated Samples

USGS Publications Warehouse

Williams, John R.; Galloway, John P.

1986-01-01

The purpose of this report is to make available basic data on radiocarbon dating of 61 organic samples from 40 locations in the western Copper River Basin and adjacent uplands and in the uppermost Matanuska River Valley. The former distribution of late Quaternary glacial lakes and of glaciers as mapped from field work and photo interpretation is provided as background for interpretation of the radiocarbon dates and are the basic data needed for construction of the late Quaternary chronology. The glacial boundaries, formed and expressed by moraines, ice-contact margins, marginal channels, deltas, and other features, are obscured by a drape of glaciolacustrine deposits in a series of glacial lakes. The highest lake, represented by bottom sediments as high as 914 m to 975 m above sea level, extends from Fog Lakes lowland on Susitna River upstream into the northwestern part of the Copper River Basin (the part now draining to Susitna River) where it apparently was held in by an ice border. It was apparently dammed by ice from the Mt. McKinley area, by Talkeetna G1acier, and may have had a temporary drainage threshold at the headwaters of Chunilna Creek. No shorelines have been noted within the map area, although Nichols and Yehle (1961) reported shorelines within the 914-975 m range in the Denali area to the north of that mapped. Recent work by geologic consultants for the Susitna Hydroelectric Project has confirmed the early inferences (Karlstrom, 1964) about the existence of a lake in the Susitna canyon, based originally on drilling by the Bureau of Reclamation about 35 years ago. According to dating of deposits at Tyone Bluff (map locations 0, P), Thorson and others (1981) concluded that a late Wisconsin advance of the glaciers between 11,535 and 21,730 years ago was followed by a brief interval of lacustrine sedimentation, and was preceded by a long period of lake deposition broken by a lowering of the lake between 32,000 and about 25,000 years ago. An alternate interpretation of the late Wisconsin till at Tyone Bluff is that it is a glaciolacustrine diamicton of the 914-975 m lake into which the ice advanced to the Hatchet Lake and to the Old Man moraines. The level of this regional lake in the Susitna drainage and on Heartland Ridge then dropped from over 914 m to about 777 m, to uncover the Tyone Spillway. An intermediate lake level in the Susitna-Tyone-Louise lake region was lowered rapidly by erosion of the spillway to 747 m. The drainage of the 747 m lake was concentrated in the spillway leading west from the West Fork Gulkana River. This spillway or a rock threshold downstream apparently was stable enough to permit formation of basin-wide, apparently undeformed, shoreline systems at 747 m, and, on recession, local shorelines at 717 m and 700 m and lower levels. The level of the 747 m lake that was confined to about 9000 km2 of the present Copper River Basin fluctuated for one or more reasons such as: the volume of ice added to or withdrawn from the system, because of changes in water budget (assuming no outflow), and/or because of temporary releases through the only outlets, perhaps Mentasta Pass, but importantly, the Copper River canyon. The 747 m lake persisted until glaciers had withdrawn to well within the Chugach Mountains, perhaps 10 to 20 km from the present glaciers.

Cartographic evidence of the disastrous ice flood of 1809 and its aftermath (Danube River, Slovakia).

NASA Astrophysics Data System (ADS)

Pišút, P.

2009-04-01

The 18th and early 19th century river maps are important data sources for studying past landscapes. This is not only as a result of improved surveying techniques, but also because they depict landscape during probably the most important climatic and land-use changes since the Middle Ages. In this phase of the increased river activity during the last onset of the so-called Little Ice Age period, several major flood events occured. Local manuscript maps, which often depict the channel in major detail, help us to obtain a better understanding of their geomorphic and other impacts. The catastrophic ice flood, which occured on the Middle Danube river at the end of January 1809 was undoubtedly the most disastrous event of its kind in Slovakia, although it also hit a number of settlements in Lower Austria and Hungary. Several people drowned and the flood also resulted in great damage to settlements and livestock. Devastating effects of this flood particularly as to the towns of Bratislava and Komárno/Komárom were comparable with effects of disastrous floods of February 1830 in Vienna (Austria), March 1838 in Buda/Pest (Hungary) or 1845 flood in Prague (Czech Republic), respectively. In case of the present Slovakian capital Bratislava, on January 29, 1809, two ice barriers suddenly rose the water up to 10 m above the zero level and the river quickly overflowed its banks inundating the low-lying parts of the town. The flood blacked out communications with neighbouring regions. Record-breaking height of water led to breaches of the important right-bank embankment (constructed in 1770s). Through several openings water flooded the right bank, almost completely destroying the adjacent village of Petržalka/Engerau. The damage to Vienna highway levee was so massive that it only could be repaired 16 years later, in 1825-6 (although this was also due to Napoleonic wars). The flood also reactivated the Chorvátske rameno anabranch, 33 years after its abandonment. A number of local manuscript maps depict the river before and after this event. Combined with written literary reports, the maps allow us to describe the course, the devastating effects and the aftermath consequences of the 1809 flood precisely, particularly as to the territory of the city of Bratislava itself. Moreover, many of these maps comprise a wealth of information about flood in their detailed explanatory legends and remarks. The most important maps and plans are those currently deposited in the National Archives of Hungary (= maps from the collection of former Governing Council, the central supervisory authority of the Habsburgs for the Hungarian Kingdom), in the Municipial Archives of Bratislava and the Slovak National Archives, respectively. Effects of the 1809 ice flood, as evidenced by historical maps and plans, can be generally summarised as follows: a) direct destruction (by ice floes) or collapse of houses, bridges, buildings, boat mills, groynes and bank revetments b) heavy lateral erosion of the river channel during this single event (then referred to as „damage to banks") c) breaches of protective dikes d) formation of new water bodies - temporary lakes - created by spilled water on the landside of levees e) reactivation of upstream entrances of some side channels f) pronounced changes of flooplain configuration g) damage to floodplain forest. This research was supported by the Slovak Scientific Grant agency VEGA (Project N. 1/0362/09).

Studies of the inner shelf and coastal sedimentation environment of the Beaufort Sea from ERTS-1

NASA Technical Reports Server (NTRS)

Reimnitz, E. (Principal Investigator); Barnes, P. W.

1973-01-01

The author has identified the following significant results. The particulate transport processes involved in the movement of surficial waters were examined using secchi disc readings, light attenuation coefficients, and particulate weights from filtration. Observations gathered during the summers of 1971 and 1972 indicate a remarkable difference in particulate matter and turbidity between the two years. ERTS-1 imagery during August 1972 showed turbid water along the northern Alaska coast. The uniformity of distribution of the turbid water and the fact that the river discharge is low at this period suggest that the turbidity is related to causes other than river effluent. Studies indicate that wave action is a more significant factor influencing particulate transport than believed heretofore. The boundary between the essentially immobile shorefast ice and the moving pack ice has been plotted from several ERTS-1 images and found to occur fairly consistently along the 20 meter contour. Considering the vast difference in the amount of ice movement shoreward and seaward of this boundary, ice-bottom action should also be different on either side of this boundary and for that matter at the shear zone that develops along the boundary.

Using isotope, hydrochemical methods and energy-balance modelling to estimate contribution of different components to flow forming process in a high-altitude catchment (Dzhancuat river basin case study)

NASA Astrophysics Data System (ADS)

Rets, Ekaterina; Loshakova, Nadezhda; Chizhova, Julia; Kireeva, Maria; Frolova, Natalia; Tokarev, Igor; Budantseva, Nadine; Vasilchuk, Yurij

2016-04-01

A multicomponent structure of sources of river runoff formation is characteristic of high-altitude territories: ice and firn melting; seasonal snow melting on glacier covered and non-glacier area of a watershed; liquid precipitation; underground waters. In addition, each of these components can run off the watershed surface in different ways. Use of isotopic, hydrochemical methods and energy balance modelling provides possibility to estimate contribution of different components to river runoff that is an essential to understand the mechanism of flow formation in mountainious areas. A study was carried out for Dzhancuat river basin that was chosen as representative for North Caucasus in course of the International Hydrological Decade. Complex glaciological, hydrological and meteorological observation have been carried in the basin since 1965. In years 2013-2015 the program also included daily collecting of water samples on natural stable isotopes on the Dzhancuat river gauging station, and sampling water nourishment sources (ice, snow, firn, liquid precipitation) within the study area. More then 800 water samples were collected. Application of an energy balance model of snow and ice melt with distributed parameters provided an opportunity to identify Dzhancuat river runoff respond to glaciers melt regime and seasonal redistribution of melt water. The diurnal amplitude of oscillation of the Dzhakuat river runoff in the days without precipitation is formed by melting at almost snow-free areas of the Dzhancuat glacier tongues. Snowmelt water from the non-glacierized part contributes to the formation of the next day runoff. A wave of snow and firn melt in upper zones of glacier flattens considerably during filtration through snow and run-off over the surface and in the body of the glacier. This determines a general significant inertia of the Dzhacuat river runoff. Some part of melt water is stored into natural regulating reservoirs of the watershed that supply the Dzhancuat river flow during the winter period. Due to complexity of water flow nourishment structure in alpine conditions a solution of ion and d18O balance equation was carried out for seasons, when it is possible to neglect some of the components in order to reach a needed amount of variables. A substantial excess of d18O content in spring snow and liquid precipitation over winter snow, ice and firn allowed to distinguish these components in the Dzhancuat river runoff in June and August. Unlike d18O mineralization is a nonconservative characteristic, it can show how the water ran down the watershed: over a glacier surface and then through stream channels or over a non-glacier surface, filtrating through comminuted surficial deposits. A solution of conductivity balance equation provide possibility to identify a base flow component in the Dzhancuat river runoff in August and to separate an on-glacier snow melt component from snow melt on non-glacier part of the watershed. The study was supported by the Russian Foundation for Basic Research (Project № 16-35-60042), Russian Scientific fund (Project № 14-17-00766, 14-27-00083)

Floods of 1950 in the upper Mississippi River and Lake Superior basins in Minnesota

USGS Publications Warehouse

Paulsen, C.G.

1953-01-01

In areal coverage and magnitude of peak discharge the floods of April-May 1950 in the Missouri River Basin in North and South Dakota were unprecedented in the area. These floods were characterized by an extremely late spring breakup of ice, by great flood peaks resulting from snow melt, and by two separate floods in the James River Valley in less than a month. The primary cause of the floods was the rapid melting of the season's great accumulation of snow, one of the deepest on record. In the period between the normal spring breakup time and the actual breakup of river ice, considerably more snow accumulated. Some of this was melted by a few .warm days and the melt was stored as water behind snow barriers in upland watercourses. A sudden increase in temperature beginning April 13 and lasting until most of the snow had been converted into runoff resulted in rapid rise of flood waters. Tributary flood waters made the Missouri River from Mobridge to Yankton, S. Oak., rise to near the maximum recorded discharge. At Sioux City, Iowa, the 1950 flood peak-discharge exceeded any previously recorded by the Geological Survey. The center of the flooded area west of the Missouri River lay m the Cannonball River Basin which had the greatest water content of snow on the ground just before the ice broke up Floods north and south of this area were relatively less intense. Scattered records of the Cannonball River and a study of newspaper accounts and other information show that the flood of 1950 was greatest since the area was settled. Flooding of the James River at Jamestown was the greatest since 1897, and the floods of April and May 1950 were of nearly the same stage. Itemized flood damages were made by Federal and State agencies, and relief was sent to the area by the Department of the Army and the American National Red Cross. Data include records of stage and discharge at 54 gaging stations for the period of flood, a summary of peak discharges and comparative data for past and present maxima, a table of crest stages, and weather associated with the 1950 flood.

The impact of dissolved organic carbon and bacterial respiration on pCO2 in experimental sea ice

NASA Astrophysics Data System (ADS)

Zhou, J.; Kotovitch, M.; Kaartokallio, H.; Moreau, S.; Tison, J.-L.; Kattner, G.; Dieckmann, G.; Thomas, D. N.; Delille, B.

2016-02-01

Previous observations have shown that the partial pressure of carbon dioxide (pCO2) in sea ice brines is generally higher in Arctic sea ice compared to those from the Antarctic sea ice, especially in winter and early spring. We hypothesized that these differences result from the higher dissolved organic carbon (DOC) content in Arctic seawater: Higher concentrations of DOC in seawater would be reflected in a greater DOC incorporation into sea ice, enhancing bacterial respiration, which in turn would increase the pCO2 in the ice. To verify this hypothesis, we performed an experiment using two series of mesocosms: one was filled with seawater (SW) and the other one with seawater with an addition of filtered humic-rich river water (SWR). The addition of river water increased the DOC concentration of the water from a median of 142 μmol Lwater-1 in SW to 249 μmol Lwater-1 in SWR. Sea ice was grown in these mesocosms under the same physical conditions over 19 days. Microalgae and protists were absent, and only bacterial activity has been detected. We measured the DOC concentration, bacterial respiration, total alkalinity and pCO2 in sea ice and the underlying seawater, and we calculated the changes in dissolved inorganic carbon (DIC) in both media. We found that bacterial respiration in ice was higher in SWR: median bacterial respiration was 25 nmol C Lice-1 h-1 compared to 10 nmol C Lice-1 h-1 in SW. pCO2 in ice was also higher in SWR with a median of 430 ppm compared to 356 ppm in SW. However, the differences in pCO2 were larger within the ice interiors than at the surfaces or the bottom layers of the ice, where exchanges at the air-ice and ice-water interfaces might have reduced the differences. In addition, we used a model to simulate the differences of pCO2 and DIC based on bacterial respiration. The model simulations support the experimental findings and further suggest that bacterial growth efficiency in the ice might approach 0.15 and 0.2. It is thus credible that the higher pCO2 in Arctic sea ice brines compared with those from the Antarctic sea ice were due to an elevated bacterial respiration, sustained by higher riverine DOC loads. These conclusions should hold for locations and time frames when bacterial activity is relatively dominant compared to algal activity, considering our experimental conditions.

Design of river height and speed monitoring system by using Arduino

NASA Astrophysics Data System (ADS)

Nasution, T. H.; Siagian, E. C.; Tanjung, K.; Soeharwinto

2018-02-01

River is one part of the hydrologic cycle. Water in rivers is generally collected from precipitation, such as rain, dew, springs, underground runoff, and in certain countries also comes from melt ice/snow. The height and speed of water in a river is always changing. Changes in altitude and speed of water can affect the surrounding environment. In this paper, we will design a system to measure the altitude and speed of the river. In this work we use Arduino Uno, ultrasonic sensors and flow rate sensors. Ultrasonic sensor HC-SR04 is used as a river height meter. Based on the test results, this sensor has an accuracy of 96.6%.

Similkameen River Multipurpose Project Feasibility Study, Cultural Resource Reconnaissance

DTIC Science & Technology

1987-04-01

fill below the vicinity of Nighthawk. Soil survey data and well drilling logs suggest that a large block of ice occupied the western half of Palmer Lake...granodiorite on the south side of the river opposite the staging gauge at R.M. 15.3 (Rinehart and Fox 1972); the north side of the river does not...Utilized 7 Penetration Drilling Drill 1 Projectile Impact Projectile Point 10 Percussion Chopping Chopper 2 Flaking Complete Flake 84 Broken Flake 40

Ice patterns and hydrothermal plumes, Lake Baikal, Russia - Insights from Space Shuttle hand-held photography

NASA Technical Reports Server (NTRS)

Evans, Cynthia A.; Helfert, Michael R.; Helms, David R.

1992-01-01

Earth photography from the Space Shuttle is used to examine the ice cover on Lake Baikal and correlate the patterns of weakened and melting ice with known hydrothermal areas in the Siberian lake. Particular zones of melted and broken ice may be surface expressions of elevated heat flow in Lake Baikal. The possibility is explored that hydrothermal vents can introduce local convective upwelling and disrupt a stable water column to the extent that the melt zones which are observed in the lake's ice cover are produced. A heat flow map and photographs of the lake are overlaid to compare specific areas of thinned or broken ice with the hot spots. The regions of known hydrothermal activity and high heat flow correlate extremely well with circular regions of thinned ice, and zones of broken and recrystallized ice. Local and regional climate data and other sources of warm water, such as river inlets, are considered.

Sediment fluxes and delta evolution at Tuapaat, Disko Island, Greenland

NASA Astrophysics Data System (ADS)

Kroon, A.; Andersen, T. J.; Bendixen, M.

2013-12-01

Ice and snow and freezing temperatures have an important influence on the coastal morphodynamics in arctic polar coastal environments. Global climate changes induce many changes along the arctic coasts. Sea-levels are rising due to thermal expansion and due to an increased fresh water flux from the glaciers and land ice masses while ice coverage of the coastal waters decreases and the open water periods in summer extend. On a yearly basis, there is a strong variation over the seasons with open waters and active rivers in summer and ice-covered coastal waters and inactive rivers in winter. The coastal processes by waves and tides are thus often limited to the summer and early fall. On a daily basis, there is also a strong variation in fluvial discharges due to the daily variations in glacier melt with maximum melt in the afternoon and minimum values at night. At the same time, the actual flux of the river to the coastal bay is also influenced by the tidal phase: low tides in the afternoon will probably give the maximum plumes in the coastal waters and high tides in the early morning will reduce the input of sediments to the coastal waters to zero. The southern shore of Disko Island in western Greenland has four deltas: Igpik, Signiffik, Tuappat and Skansen. The sediments of these deltas are a mixture of sand and gravel and they are fed by melting glaciers. The Tuapaat delta is located at the end of a pro-glacial and fluvial valley at about 16 km from the glacier. The shores of the delta are reworked by waves, predominantly from southwestern (largest fetch, over 50 km), southern, and southeastern directions. The environment has a micro- to meso- tidal range with a spring tidal range of 2.7m. The morphologic changes on the delta over the last decades clearly showed an eastward migration of the main delta channel, probably due to wave-driven alongshore processes in the ice-free periods. In this presentation, we focus on quantification of sediment fluxes on the Tuapaat delta in western Greenland. We highlight the variation of the fluxes over days with changing river discharges and tidal phases. We use field observations of discharges and sediment fluxes at the lower part of the river close to the delta apex and at the delta mouth (ADV-frame and CTD-observations) during an 8 days period from neap-tide to spring-tide in July 2013. Besides, we estimate the wave impact during the period, using climatic variables and a numerical model.

Deterioration and Repair of Concrete in the Lower Monumental Navigation Lock Wall.

DTIC Science & Technology

1981-06-01

Lewiston , ID, along the Columbia and Snake Rivers. Because there are no alternate waterways or lock, the transportation system stops if the lock is...tem 3 Page 1 of 1 LOWER SNAKE RIVER PROJECT LOWERGRANITE 7.0 Lewiston LFliLE GOOSE C LOWER ~ MONUMENTAL ~rDN LCOWER SNAKE Tri-cites ICE HAROBO R ASH

Direct measurements of meltwater runoff on the Greenland ice sheet surface

NASA Astrophysics Data System (ADS)

Smith, Laurence C.; Yang, Kang; Pitcher, Lincoln H.; Overstreet, Brandon T.; Chu, Vena W.; Rennermalm, Åsa K.; Ryan, Jonathan C.; Cooper, Matthew G.; Gleason, Colin J.; Tedesco, Marco; Jeyaratnam, Jeyavinoth; van As, Dirk; van den Broeke, Michiel R.; van de Berg, Willem Jan; Noël, Brice; Langen, Peter L.; Cullather, Richard I.; Zhao, Bin; Willis, Michael J.; Hubbard, Alun; Box, Jason E.; Jenner, Brittany A.; Behar, Alberto E.

2017-12-01

Meltwater runoff from the Greenland ice sheet surface influences surface mass balance (SMB), ice dynamics, and global sea level rise, but is estimated with climate models and thus difficult to validate. We present a way to measure ice surface runoff directly, from hourly in situ supraglacial river discharge measurements and simultaneous high-resolution satellite/drone remote sensing of upstream fluvial catchment area. A first 72-h trial for a 63.1-km2 moulin-terminating internally drained catchment (IDC) on Greenland's midelevation (1,207–1,381 m above sea level) ablation zone is compared with melt and runoff simulations from HIRHAM5, MAR3.6, RACMO2.3, MERRA-2, and SEB climate/SMB models. Current models cannot reproduce peak discharges or timing of runoff entering moulins but are improved using synthetic unit hydrograph (SUH) theory. Retroactive SUH applications to two older field studies reproduce their findings, signifying that remotely sensed IDC area, shape, and supraglacial river length are useful for predicting delays in peak runoff delivery to moulins. Applying SUH to HIRHAM5, MAR3.6, and RACMO2.3 gridded melt products for 799 surrounding IDCs suggests their terminal moulins receive lower peak discharges, less diurnal variability, and asynchronous runoff timing relative to climate/SMB model output alone. Conversely, large IDCs produce high moulin discharges, even at high elevations where melt rates are low. During this particular field experiment, models overestimated runoff by +21 to +58%, linked to overestimated surface ablation and possible meltwater retention in bare, porous, low-density ice. Direct measurements of ice surface runoff will improve climate/SMB models, and incorporating remotely sensed IDCs will aid coupling of SMB with ice dynamics and subglacial systems.

Direct measurements of meltwater runoff on the Greenland ice sheet surface.

PubMed

Smith, Laurence C; Yang, Kang; Pitcher, Lincoln H; Overstreet, Brandon T; Chu, Vena W; Rennermalm, Åsa K; Ryan, Jonathan C; Cooper, Matthew G; Gleason, Colin J; Tedesco, Marco; Jeyaratnam, Jeyavinoth; van As, Dirk; van den Broeke, Michiel R; van de Berg, Willem Jan; Noël, Brice; Langen, Peter L; Cullather, Richard I; Zhao, Bin; Willis, Michael J; Hubbard, Alun; Box, Jason E; Jenner, Brittany A; Behar, Alberto E

2017-12-12

Meltwater runoff from the Greenland ice sheet surface influences surface mass balance (SMB), ice dynamics, and global sea level rise, but is estimated with climate models and thus difficult to validate. We present a way to measure ice surface runoff directly, from hourly in situ supraglacial river discharge measurements and simultaneous high-resolution satellite/drone remote sensing of upstream fluvial catchment area. A first 72-h trial for a 63.1-km 2 moulin-terminating internally drained catchment (IDC) on Greenland's midelevation (1,207-1,381 m above sea level) ablation zone is compared with melt and runoff simulations from HIRHAM5, MAR3.6, RACMO2.3, MERRA-2, and SEB climate/SMB models. Current models cannot reproduce peak discharges or timing of runoff entering moulins but are improved using synthetic unit hydrograph (SUH) theory. Retroactive SUH applications to two older field studies reproduce their findings, signifying that remotely sensed IDC area, shape, and supraglacial river length are useful for predicting delays in peak runoff delivery to moulins. Applying SUH to HIRHAM5, MAR3.6, and RACMO2.3 gridded melt products for 799 surrounding IDCs suggests their terminal moulins receive lower peak discharges, less diurnal variability, and asynchronous runoff timing relative to climate/SMB model output alone. Conversely, large IDCs produce high moulin discharges, even at high elevations where melt rates are low. During this particular field experiment, models overestimated runoff by +21 to +58%, linked to overestimated surface ablation and possible meltwater retention in bare, porous, low-density ice. Direct measurements of ice surface runoff will improve climate/SMB models, and incorporating remotely sensed IDCs will aid coupling of SMB with ice dynamics and subglacial systems. Copyright © 2017 the Author(s). Published by PNAS.

Direct measurements of meltwater runoff on the Greenland ice sheet surface

PubMed Central

Smith, Laurence C.; Yang, Kang; Pitcher, Lincoln H; Overstreet, Brandon T.; Chu, Vena W.; Rennermalm, Åsa K.; Ryan, Jonathan C.; Cooper, Matthew G.; Gleason, Colin J.; Tedesco, Marco; Jeyaratnam, Jeyavinoth; van As, Dirk; van den Broeke, Michiel R.; van de Berg, Willem Jan; Noël, Brice; Langen, Peter L.; Cullather, Richard I.; Zhao, Bin; Hubbard, Alun; Box, Jason E.; Jenner, Brittany A.; Behar, Alberto E.

2017-01-01

Meltwater runoff from the Greenland ice sheet surface influences surface mass balance (SMB), ice dynamics, and global sea level rise, but is estimated with climate models and thus difficult to validate. We present a way to measure ice surface runoff directly, from hourly in situ supraglacial river discharge measurements and simultaneous high-resolution satellite/drone remote sensing of upstream fluvial catchment area. A first 72-h trial for a 63.1-km2 moulin-terminating internally drained catchment (IDC) on Greenland’s midelevation (1,207–1,381 m above sea level) ablation zone is compared with melt and runoff simulations from HIRHAM5, MAR3.6, RACMO2.3, MERRA-2, and SEB climate/SMB models. Current models cannot reproduce peak discharges or timing of runoff entering moulins but are improved using synthetic unit hydrograph (SUH) theory. Retroactive SUH applications to two older field studies reproduce their findings, signifying that remotely sensed IDC area, shape, and supraglacial river length are useful for predicting delays in peak runoff delivery to moulins. Applying SUH to HIRHAM5, MAR3.6, and RACMO2.3 gridded melt products for 799 surrounding IDCs suggests their terminal moulins receive lower peak discharges, less diurnal variability, and asynchronous runoff timing relative to climate/SMB model output alone. Conversely, large IDCs produce high moulin discharges, even at high elevations where melt rates are low. During this particular field experiment, models overestimated runoff by +21 to +58%, linked to overestimated surface ablation and possible meltwater retention in bare, porous, low-density ice. Direct measurements of ice surface runoff will improve climate/SMB models, and incorporating remotely sensed IDCs will aid coupling of SMB with ice dynamics and subglacial systems. PMID:29208716

Trends in annual minimum exposed snow and ice cover in High Mountain Asia from MODIS

NASA Astrophysics Data System (ADS)

Rittger, Karl; Brodzik, Mary J.; Painter, Thomas H.; Racoviteanu, Adina; Armstrong, Richard; Dozier, Jeff

2016-04-01

Though a relatively short record on climatological scales, data from the Moderate Resolution Imaging Spectroradiometer (MODIS) from 2000-2014 can be used to evaluate changes in the cryosphere and provide a robust baseline for future observations from space. We use the MODIS Snow Covered Area and Grain size (MODSCAG) algorithm, based on spectral mixture analysis, to estimate daily fractional snow and ice cover and the MODICE Persistent Ice (MODICE) algorithm to estimate the annual minimum snow and ice fraction (fSCA) for each year from 2000 to 2014 in High Mountain Asia. We have found that MODSCAG performs better than other algorithms, such as the Normalized Difference Index (NDSI), at detecting snow. We use MODICE because it minimizes false positives (compared to maximum extents), for example, when bright soils or clouds are incorrectly classified as snow, a common problem with optical satellite snow mapping. We analyze changes in area using the annual MODICE maps of minimum snow and ice cover for over 15,000 individual glaciers as defined by the Randolph Glacier Inventory (RGI) Version 5, focusing on the Amu Darya, Syr Darya, Upper Indus, Ganges, and Brahmaputra River basins. For each glacier with an area of at least 1 km2 as defined by RGI, we sum the total minimum snow and ice covered area for each year from 2000 to 2014 and estimate the trends in area loss or gain. We find the largest loss in annual minimum snow and ice extent for 2000-2014 in the Brahmaputra and Ganges with 57% and 40%, respectively, of analyzed glaciers with significant losses (p-value<0.05). In the Upper Indus River basin, we see both gains and losses in minimum snow and ice extent, but more glaciers with losses than gains. Our analysis shows that a smaller proportion of glaciers in the Amu Darya and Syr Darya are experiencing significant changes in minimum snow and ice extent (3.5% and 12.2%), possibly because more of the glaciers in this region are smaller than 1 km2 than in the Indus, Ganges, and Brahmaputra making analysis from MODIS (pixel area ~0.25 km2) difficult. Overall, we see 23% of the glaciers in the 5 river basins with significant trends (in either direction). We relate these changes in area to topography and climate to understand the driving processes related to these changes. In addition to annual minimum snow and ice cover, the MODICE algorithm also provides the date of minimum fSCA for each pixel. To determine whether the surface was snow or ice we use the date of minimum fSCA from MODICE to index daily maps of snow on ice (SOI), or exposed glacier ice (EGI) and systematically derive an equilibrium line altitude (ELA) for each year from 2000-2014. We test this new algorithm in the Upper Indus basin and produce annual estimates of ELA. For the Upper Indus basin we are deriving annual ELAs that range from 5350 m to 5450 m which is slightly higher than published values of 5200 m for this region.

Marine biological controls on atmospheric CO2 and climate

NASA Technical Reports Server (NTRS)

Mcelroy, M. B.

1983-01-01

It is argued that the ocean is losing N gas faster than N is being returned to the ocean, and that replenishment of the N supply in the ocean usually occurs during ice ages. Available N from river and estruarine transport and from rainfall after formation by lightning are shown to be at a rate too low to compensate for the 10,000 yr oceanic lifetime of N. Ice sheets advance and transfer moraine N to the ocean, lower the sea levels, erode the ocean beds, promote greater biological productivity, and reduce CO2. Ice core samples have indicated a variability in the atmospheric N content that could be attributed to the ice age scenario.

Susceptibility of central hardwood trees to stem breakage due to ice glazing

Treesearch

KaDonna C. Randolph

2014-01-01

During January 26-28, 2009, a winter storm dropped a mix of rain, ice, and snow from Texas across the Ohio River Valley and into New England. The storm caused multiple fatalities and millions of dollars of property damage and was called "the biggest natural disaster in modern Kentucky history" (Brammer and Funk 2009: 13). The storm disturbed an estimated 2.4...

Role of stream ice on fall and winter movements and habitat use by bull trout and cutthroat trout in Montana headwater streams

Treesearch

Michael J. Jakober; Thomas E. McMahon; Russell F. Thurow; Christopher G. Clancy

1998-01-01

We used radiotelemetry and underwater observation to assess fall and winter movements and habitat use by bull trout Salvelinus confluentus and westslope cutthroat trout Oncorhynchus clarki lewisi in two headwater streams in the Bitterroot River drainage, Montana, that varied markedly in habitat availability and stream ice conditions. Bull trout and cutthroat trout made...

Lena River, Russia

NASA Technical Reports Server (NTRS)

2002-01-01

This pair of true- and false-color images from the Moderate Resolution Imaging Spectroradiometer (MODIS) from June 28, 2002, shows numerous burn scars dotting the northern Siberian landscape along the Lena River. In the true-color image, the burn scars appear dark grayish-brown, while in the false-color image they appear red, as does the bare exposed soil of the Verkhoyansk Mountain Range to the east of the north-flowing Lena. A tinge of blue along the mountains in the false-color image means there is some lingering snow or ice, and that the bare soil is due to spring's late arrival there, and not to burn scars. At the top, sea ice still fills the Laptev Sea. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

Late Pleistocene eolian features in southeastern Maryland and Chesapeake Bay region indicate strong WNW-NW winds accompanied growth of the Laurentide Ice Sheet

NASA Astrophysics Data System (ADS)

Markewich, Helaine W.; Litwin, Ronald J.; Pavich, Milan J.; Brook, George A.

2009-05-01

Inactive parabolic dunes are present in southeastern Maryland, USA, along the east bank of the Potomac River. More elongate and finer-grained eolian deposits and paha-like ridges characterize the Potomac River-Patuxent River upland and the west side of Chesapeake Bay. These ridges are streamlined erosional features, veneered with eolian sediment and interspersed with dunes in the low-relief headwaters of Potomac- and Patuxent-river tributaries. Axis data for the dunes and ridges indicate formation by WNW-NW winds. Optically stimulated luminescence and radiocarbon age data suggest dune formation from ˜ 33-15 ka, agreeing with the 30-13 ka ages Denny, C.S., Owens, J.P., Sirkin, L., Rubin, M., 1979. The Parsonburg Sand in the central Delmarva Peninsula, Maryland and Delaware. U.S. Geol. Surv. Prof. Pap. 1067-B, 16 pp. suggested for eolian deposits east of Chesapeake Bay. Age range and paleowind direction(s) for eolian features in the Bay region approximate those for late Wisconsin loess in the North American midcontinent. Formation of midcontinent loess and Bay-region eolian features was coeval with rapid growth of the Laurentide Ice Sheet and strong cooling episodes (δ 18O minima) evident in Greenland ice cores. Age and paleowind-direction coincidence, for eolian features in the midcontinent and Bay region, indicates strong mid-latitude WNW-NW winds for several hundred kilometers south of the Laurentide glacial terminus that were oblique to previously simulated anticyclonic winds for the last glacial maximum.

Interactions between surface waters in King George Island, Antarctica - a stable isotope perspective

NASA Astrophysics Data System (ADS)

Perşoiu, Aurel; Bădăluşă, Carmen

2017-04-01

In this paper we present a first study of the isotopic composition of surface waters in the southern peninsulas (Barton, Fildes, Weaver and Potter) of King George Island, Antarctica. We have collected > 200 samples of snow and snowmelt, water (lake, river and spring), ice (glacier ice and permafrost) from the four peninsulas in February 2016 and analyzed them for their oxygen and hydrogen stable isotopic composition. Samples from lake water (50+) indicate a clear west-east depletion trend, suggesting a rain-out process as air masses are moving westward (and are progressively depleted in heavy isotopes) from their origin in the Drake Passage. In both Fildes and Barton Peninsulas, permafrost samples have the heaviest isotopic composition, most probably due to preferential incorporation of heavy isotopes in the ice during freezing (and no fractionation during melting). As permafrost melts, the resulting water mixes with isotopically lighter infiltrated snowmelt, and thus the groundwater has a lower isotopic composition. Further, lake and river (the later fed by lakes) water has the lightest isotopic composition, being derived mostly from the melting of light snow and glacier ice. It seems feasible to separate isotopically water in lakes/rivers (largely fed by melting multi-year glaciers and snow) and water from melting of snow/ground ice This preliminary study suggests that it is possible to separate various water sources in the southern peninsulas of King George Island, and this separation could be used to study permafrost degradation, as well as feeding and migration patterns in the bird fauna, with implications for protection purposes. Acknowledgments. The National Institute of Research and Development for Biological Sciences (Bucharest, Romania) and the Korean polar institute financially supported fieldwork in King George Island. We thank the personal at King Sejong (South Korea), Belingshaussen (Russia) and Carlini (Argentina) stations in King George Island for logistic supports.

Review of behaviour of oil in freezing environments.

PubMed

Fingas, M F; Hollebone, B P

2003-01-01

The current knowledge of the physical fate and behaviour of crude oil and petroleum products spilled in Arctic situations is reviewed. The fate and final deposition of oil in marine conditions is presented as based on the extant literature. Spreading models were evaluated for oil on ice, under ice, in snow, in brash ice, and between blocks of ice. Models of oil transport under sheet and broken ice were considered, both for sea and river conditions. The ability of ice sheets to trap oil is discussed in relation to oil storage capacity. The effects of oil on a growing ice sheet were examined, both in terms of ice formation and the thermal effects of oil inclusions in ice. The migration of oil through ice was reviewed, focussing primarily on the movement through brine channels. The effects of oil on the surface of ice were considered, with emphasis on the effects of surface pools on ice melt. Similar consideration was given to the effects of oil on snow on the surface of ice. The few quantitative studies of oil in open and dynamic ice conditions are reviewed. Observations of intentional small-scale spills in leads and ice fields are reviewed and compared with observations from real spills. The conditions under which "oil pumping" from leads occurs were quantified. The most common ultimate fate of oil in an ice field is to be released onto the water surface.

33 CFR 207.718 - Navigation locks and approach channels, Columbia and Snake Rivers, Oreg. and Wash.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Ice Harbor, WUJ 43 Lower Monumental, WUJ 44 Little Goose, or WUJ 45 Lower Granite, at least one-half... is 19 feet. When the river flow at Lower Granite exceeds 330,000 cubic feet per second the normal... Lower Granite Lock and Dam. The waters restricted to all vessels, except Government vessels, are...

33 CFR 207.718 - Navigation locks and approach channels, Columbia and Snake Rivers, Oreg. and Wash.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Ice Harbor, WUJ 43 Lower Monumental, WUJ 44 Little Goose, or WUJ 45 Lower Granite, at least one-half... is 19 feet. When the river flow at Lower Granite exceeds 330,000 cubic feet per second the normal... Lower Granite Lock and Dam. The waters restricted to all vessels, except Government vessels, are...

33 CFR 207.718 - Navigation locks and approach channels, Columbia and Snake Rivers, Oreg. and Wash.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Ice Harbor, WUJ 43 Lower Monumental, WUJ 44 Little Goose, or WUJ 45 Lower Granite, at least one-half... is 19 feet. When the river flow at Lower Granite exceeds 330,000 cubic feet per second the normal... Lower Granite Lock and Dam. The waters restricted to all vessels, except Government vessels, are...

33 CFR 207.718 - Navigation locks and approach channels, Columbia and Snake Rivers, Oreg. and Wash.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Ice Harbor, WUJ 43 Lower Monumental, WUJ 44 Little Goose, or WUJ 45 Lower Granite, at least one-half... is 19 feet. When the river flow at Lower Granite exceeds 330,000 cubic feet per second the normal... Lower Granite Lock and Dam. The waters restricted to all vessels, except Government vessels, are...

33 CFR 207.718 - Navigation locks and approach channels, Columbia and Snake Rivers, Oreg. and Wash.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Ice Harbor, WUJ 43 Lower Monumental, WUJ 44 Little Goose, or WUJ 45 Lower Granite, at least one-half... is 19 feet. When the river flow at Lower Granite exceeds 330,000 cubic feet per second the normal... Lower Granite Lock and Dam. The waters restricted to all vessels, except Government vessels, are...

Implications for carbon processing beneath the Greenland Ice Sheet from dissolved CO2 and CH4 concentrations of subglacial discharge

NASA Astrophysics Data System (ADS)

Pain, A.; Martin, J.; Martin, E. E.

2017-12-01

Subglacial carbon processes are of increasing interest as warming induces ice melting and increases fluxes of glacial meltwater into proglacial rivers and the coastal ocean. Meltwater may serve as an atmospheric source or sink of carbon dioxide (CO2) or methane (CH4), depending on the magnitudes of subglacial organic carbon (OC) remineralization, which produces CO2 and CH4, and mineral weathering reactions, which consume CO2 but not CH4. We report wide variability in dissolved CO2 and CH4 concentrations at the beginning of the melt season (May-June 2017) between three sites draining land-terminating glaciers of the Greenland Ice Sheet. Two sites, located along the Watson River in western Greenland, drain the Isunnguata and Russell Glaciers and contained 1060 and 400 ppm CO2, respectively. In-situ CO2 flux measurements indicated that the Isunnguata was a source of atmospheric CO2, while the Russell was a sink. Both sites had elevated CH4 concentrations, at 325 and 25 ppm CH4, respectively, suggesting active anaerobic OC remineralization beneath the ice sheet. Dissolved CO2 and CH4 reached atmospheric equilibrium within 2.6 and 8.6 km downstream of Isunnguata and Russell discharge sites, respectively. These changes reflect rapid gas exchange with the atmosphere and/or CO2 consumption via instream mineral weathering. The third site, draining the Kiagtut Sermiat in southern Greenland, had about half atmospheric CO2 concentrations (250 ppm), but approximately atmospheric CH4 concentrations (2.1 ppm). Downstream CO2 flux measurements indicated ingassing of CO2 over the entire 10-km length of the proglacial river. CO2 undersaturation may be due to more readily weathered lithologies underlying the Kiagtut Sermiat compared to Watson River sites, but low CH4 concentrations also suggest limited contributions of CO2 and CH4 from OC remineralization. These results suggest that carbon processing beneath the Greenland Ice Sheet may be more variable than previously recognized. Variations control whether discharge is a source or sink of atmospheric CO2 or CH4, but gas concentrations could be further modified by instream reactions. Increased meltwater fluxes should enhance the importance of greenhouse gas fluxes from subglacial discharge, and heighten the need to constrain variability in subglacial carbon processing.

Evaluation of an operational water cycle prediction system for the Laurentian Great Lakes and St. Lawrence River

NASA Astrophysics Data System (ADS)

Fortin, Vincent; Durnford, Dorothy; Smith, Gregory; Dyck, Sarah; Martinez, Yosvany; Mackay, Murray; Winter, Barbara

2017-04-01

Environment and Climate Change Canada (ECCC) is implementing new numerical guidance products based on fully coupled numerical models to better inform the public as well as specialized users on the current and future state of various components of the water cycle, including stream flow and water levels. Outputs from this new system, named the Water Cycle Prediction System (WCPS), have been available for the Great Lakes and St. Lawrence River watershed since June 2016. WCPS links together ECCC's weather forecasting model, GEM, the 2-D ice model C-ICE, the 3-D lake and ocean model NEMO, and a 2-D hydrological model, WATROUTE. Information concerning the water cycle is passed between the models at intervals varying from a few minutes to one hour. It currently produces two forecasts per day for the next three days of the complete water cycle in the Great Lakes region, the largest freshwater lake system in the world. Products include spatially-varying precipitation, evaporation, river discharge, water level anomalies, surface water temperatures, ice coverage, and surface currents. These new products are of interest to water resources and management authority, flood forecasters, hydroelectricity producers, navigation, environmental disaster managers, search and rescue teams, agriculture, and the general public. This presentation focuses on the evaluation of various elements forecasted by the system, and weighs the advantages and disadvantages of running the system fully coupled.

Spatial and temporal variability of seawater pCO2 within the Canadian Arctic Archipelago and Baffin Bay during the summer and autumn 2011

NASA Astrophysics Data System (ADS)

Geilfus, N.-X.; Pind, M. L.; Else, B. G. T.; Galley, R. J.; Miller, L. A.; Thomas, H.; Gosselin, M.; Rysgaard, S.; Wang, F.; Papakyriakou, T. N.

2018-03-01

The partial pressure of CO2 in surface water (pCO2sw) measured within the Canadian Arctic Archipelago (CAA) and Baffin Bay was highly variable with values ranging from strongly undersaturated (118 μatm) to slightly supersaturated (419 μatm) with respect to the atmospheric levels ( 386 μatm) during summer and autumn 2011. During summer, melting sea ice contributed to cold and fresh surface water and enhanced the ice-edge bloom, resulting in strong pCO2sw undersaturation. Coronation Gulf was the only area with supersaturated pCO2sw, likely due to warm CO2-enriched freshwater input from the Coppermine River. During autumn, the entire CAA (including Coronation Gulf) was undersaturated, despite generally increasing pCO2sw. Coronation Gulf was the one place where pCO2sw decreased, likely due to seasonal reduction in discharge from the Coppermine River and the decreasing sea surface temperature. The seasonal summer-to-autumn increase in pCO2sw across the archipelago is attributed in part to the continuous uptake of atmospheric CO2 through both summer and autumn and to the seasonal deepening of the surface mixed layer, bringing CO2-rich waters to the surface. These observations demonstrate how freshwater from sea ice melt and rivers affect pCO2sw differently. The general pCO2sw undersaturation during summer-autumn 2011 throughout the CAA and Baffin Bay give an estimated net oceanic sink for atmospheric CO2 over the study period of 11.4 mmol CO2 m-2 d-1, assuming no sea-air CO2 flux exchange across the sea-ice covered areas.

Physical Model Study of Cross Vanes and Ice

DTIC Science & Technology

2009-08-01

spacing since, in the pre-scour state, experiments and the HEC - RAS hydraulic model (USACE 2002b) found that water surface ele- vation merged with the...docs/eng-manuals/em1110- 2-1612/toc.htm. USACE (2002b) HEC - RAS , Hydraulic Reference Manual. US Army Corps of Engineers Hydrologic Engineering Center...Currently little design guidance is available for constructing these structures on ice-affected rivers . This study used physical and numerical

Initial mortality rates and extent of damage to loblolly and longleaf pine plantations affected by an ice storm in South Carolina

Treesearch

Don C. Bragg

2016-01-01

A major ice storm struck Georgia and the Carolinas in February of 2014, damaging or destroying hundreds of thousands of hectares of timber worth hundreds of millions of dollars. Losses were particularly severe in pine plantations in west-central South Carolina, including many on the Savannah River Site (SRS). An array of paired, mid-rotation loblolly (Pinus...

Geomorphological aspects of road construction in a cold environment, Finland

NASA Astrophysics Data System (ADS)

Seppälä, Matti

1999-12-01

Traditionally, road alignments followed easy landscapes and suitable landforms. When traffic and the size and weight of vehicles increased and higher speeds were used, straighter roads were required; the easygoing relief could not always be used, and problems arose. Road contractors could save money in building and maintenance costs by considering the geomorphic facts. The examples from Finland document why road construction is very expensive in the conditions generated by severe winters. In Finland, more paved roads cross the Arctic Circle than in the whole of North America. This paper gives examples of geomorphic elements affecting road construction in a cold environment: eskers, drumlins, plains of late and postglacial glaciolacustrine and marine sediments, mires, steep rock cliffs, river channels and ice-dams, fluvial erosion, and palsas. Solutions to these problems include removal of frost sensible materials and replacement by more favorable sediments. Road surfaces, kept snow-free in the wintertime, are subjected to deep freezing. The maintenance of roads can be supported with some solutions that affect snowdrift and icing problems, avoidance of geomorphic factors that cause problems, and by using natural processes to help people. Some examples of how road construction affects geomorphic processes and vice versa are provided. For example, bridges block moving river ice, and on special occasions, road banks cause icing.

Numerical simulation of the paleohydrology of glacial Lake Oshkosh, eastern Wisconsin, USA

USGS Publications Warehouse

Clark, J.A.; Befus, K.M.; Hooyer, T.S.; Stewart, P.W.; Shipman, T.D.; Gregory, C.T.; Zylstra, D.J.

2008-01-01

Proglacial lakes, formed during retreat of the Laurentide ice sheet, evolved quickly as outlets became ice-free and the earth deformed through glacial isostatic adjustment. With high-resolution digital elevation models (DEMs) and GIS methods, it is possible to reconstruct the evolution of surface hydrology. When a DEM deforms through time as predicted by our model of viscoelastic earth relaxation, the entire surface hydrologic system with its lakes, outlets, shorelines and rivers also evolves without requiring assumptions of outlet position. The method is applied to proglacial Lake Oshkosh in Wisconsin (13,600 to 12,900??cal yr BP). Comparison of predicted to observed shoreline tilt indicates the ice sheet was about 400??m thick over the Great Lakes region. During ice sheet recession, each of the five outlets are predicted to uplift more than 100??m and then subside approximately 30??m. At its maximum extent, Lake Oshkosh covered 6600??km2 with a volume of 111??km3. Using the Hydrologic Engineering Center-River Analysis System model, flow velocities during glacial outburst floods up to 9??m/s and peak discharge of 140,000??m3/s are predicted, which could drain 33.5??km3 of lake water in 10??days and transport boulders up to 3??m in diameter. ?? 2007 University of Washington.

Decrease in glacier coverage contributes to increased winter baseflow of Arctic rivers

NASA Astrophysics Data System (ADS)

Liljedahl, A. K.; Gaedeke, A.; Baraer, M.; Chesnokova, A.; Lebedeva, L.; Makarieva, O.; O'Neel, S.

2016-12-01

Rising minimum daily flows in northern Eurasian and North American rivers suggest a growing influence of groundwater in the Arctic hydrological cycle, while the impact of a warmer high-latitude climate system is evident in decreased glacier coverage and increasing permafrost temperatures. Multiple mechanisms have been proposed to explain the increased discharge, which is well documented but relatively poorly understood. Here we assess the long-term (up to 88 yrs) linkages between climate, glaciers and hydrology in Alaska, Canadian and Russian glacierized (from 0.3 to 60% glacier cover) and non-glacierized watersheds (31 to 186 000 km2). We are specifically interested in analyzing trends in late winter discharge from larger watersheds to refine our understanding of the regional aquifer status and annual discharge from smaller headwater basins. Field measurements of differential runoff in Interior Alaska show that glaciated headwater streams can lose significant amounts of water in summer to the underlying aquifer. The aquifer is in turn feeding the larger lowland river system throughout the year. Groundwater storage status in Arctic regions is especially prominent through winter river discharge as it is typically the only source of water to the river system for at least 6 months of the year. Our analyses aim to explore the hypothesis that the documented increase in later winter river discharge of larger watersheds can be explained at least partly, by increased glacier melt in summer as observed by long-term decreases in glacier coverage. If true, a decrease in winter freshwater exports to the Arctic Ocean could potentially follow as glaciers retreat to higher (cooler) elevations. Increased Arctic river baseflow can favor sea ice growth and fish habitats, while negatively impacting local communities in their river ice travel.

Seasonality of primary and secondary production in an Arctic river

NASA Astrophysics Data System (ADS)

Kendrick, M.; Huryn, A.; Deegan, L.

2011-12-01

Rivers and streams that freeze solid for 8-9 months each year provide excellent examples of the extreme seasonality of arctic habitats. The communities of organisms inhabiting these rivers must complete growth and development during summer, resulting in a rapid ramp-up and down of production over the short ice-free period. The effects of recent shifts in the timing of the spring thaw and autumn freeze-up on the duration and pattern of the period of active production are poorly understood. We are currently investigating: 1) the response of the biotic community of the Kuparuk River (Arctic Alaska) to shifts in the seasonality of the ice-free period, and 2) the community response to increases in phosphorous (P) supply anticipated as the volume of the permafrost active-layer increases in response to climate warming. Here algal production supports a 2-tier web of consumers. We tracked primary and secondary production from the spring thaw through mid-August in a reference reach and one receiving low-level P fertilization. Gross primary production/community respiration (GPP/R) ratios for both reaches were increasing through mid-July, with higher GPP/R in response to the P addition. Understanding the degree of synchrony between primary and secondary production in this Arctic river system will enhance further understanding of how shifts in seasonality affect trophic dynamics.

Applications of ERTS-1 imagery to terrestrial and marine environmental analyses in Alaska

NASA Technical Reports Server (NTRS)

Anderson, D. M.; Mckim, H. L.; Crowder, W. K.; Haugen, R. K.; Gatto, L. W.; Marlar, T. L.

1974-01-01

ERTS-1 imagery provides a means of distinguishing and monitoring estuarine surface water circulation patterns and changes in the relative sediment load of discharging rivers on a regional basis. It also will aid local fishing industries by augmenting currently available hydrologic and navigation charts. The interpretation of geologic and vegetation features resulted in preparation of improved surficial geology, vegetation and permafrost terrain maps at a scale of 1:1 million utilizing ERTS-1 band 7 imagery. This information will be further utilized in a route and site selection study for the Nome to Kobuk Road in central Alaska. Large river icings along the proposed Alaska pipeline route have been monitored. Sea ice deformation and drift northeast of Point Barrow, Alaska has been measured and shorefast ice accumulation and ablation along the west coast of Alaska is being mapped for the spring and early summer seasons. These data will be used for route and site selection, regional environmental analysis, identification and inventory of natural resources, land use planning, and in land use regulation and management.

Irish Ice Sheet dynamics during deglaciation of the central Irish Midlands: Evidence of ice streaming and surging from airborne LiDAR

NASA Astrophysics Data System (ADS)

Delaney, Catherine A.; McCarron, Stephen; Davis, Stephen

2018-04-01

High resolution digital terrain models (DTMs) generated from airborne LiDAR data and supplemented by field evidence are used to map glacial landform assemblages dating from the last glaciation (Midlandian glaciation; OI stages 2-3) in the central Irish Midlands. The DTMs reveal previously unrecognised low-amplitude landforms, including crevasse-squeeze ridges and mega-scale glacial lineations overprinted by conduit fills leading to ice-marginal subaqueous deposits. We interpret this landform assemblage as evidence for surging behaviour during ice recession. The data indicate that two separate phases of accelerated ice flow were followed by ice sheet stagnation during overall deglaciation. The second surge event was followed by a subglacial outburst flood, forming an intricate esker and crevasse-fill network. The data provide the first clear evidence that ice flow direction was eastward along the eastern watershed of the Shannon River basin, at odds with previous models, and raise the possibility that an ice stream existed in this area. Our work demonstrates the potential for airborne LiDAR surveys to produce detailed paleoglaciological reconstructions and to enhance our understanding of complex palaeo-ice sheet dynamics.

Enhanced ice sheet growth in Eurasia owing to adjacent ice-dammed lakes.

PubMed

Krinner, G; Mangerud, J; Jakobsson, M; Crucifix, M; Ritz, C; Svendsen, J I

2004-01-29

Large proglacial lakes cool regional summer climate because of their large heat capacity, and have been shown to modify precipitation through mesoscale atmospheric feedbacks, as in the case of Lake Agassiz. Several large ice-dammed lakes, with a combined area twice that of the Caspian Sea, were formed in northern Eurasia about 90,000 years ago, during the last glacial period when an ice sheet centred over the Barents and Kara seas blocked the large northbound Russian rivers. Here we present high-resolution simulations with an atmospheric general circulation model that explicitly simulates the surface mass balance of the ice sheet. We show that the main influence of the Eurasian proglacial lakes was a significant reduction of ice sheet melting at the southern margin of the Barents-Kara ice sheet through strong regional summer cooling over large parts of Russia. In our simulations, the summer melt reduction clearly outweighs lake-induced decreases in moisture and hence snowfall, such as has been reported earlier for Lake Agassiz. We conclude that the summer cooling mechanism from proglacial lakes accelerated ice sheet growth and delayed ice sheet decay in Eurasia and probably also in North America.

Hydrogeology of the Susquehanna River valley-fill aquifer system and adjacent areas in eastern Broome and southeastern Chenango Counties, New York

USGS Publications Warehouse

Heisig, Paul M.

2012-01-01

The hydrogeology of the valley-fill aquifer system along a 32-mile reach of the Susquehanna River valley and adjacent areas was evaluated in eastern Broome and southeastern Chenango Counties, New York. The surficial geology, inferred ice-marginal positions, and distribution of stratified-drift aquifers were mapped from existing data. Ice-marginal positions, which represent pauses in the retreat of glacial ice from the region, favored the accumulation of coarse-grained deposits whereas more steady or rapid ice retreat between these positions favored deposition of fine-grained lacustrine deposits with limited coarse-grained deposits at depth. Unconfined aquifers with thick saturated coarse-grained deposits are the most favorable settings for water-resource development, and three several-mile-long sections of valley were identified (mostly in Broome County) as potentially favorable: (1) the southernmost valley section, which extends from the New York–Pennsylvania border to about 1 mile north of South Windsor, (2) the valley section that rounds the west side of the umlaufberg (an isolated bedrock hill within a valley) north of Windsor, and (3) the east–west valley section at the Broome County–Chenango County border from Nineveh to East of Bettsburg (including the lower reach of the Cornell Brook valley). Fine-grained lacustrine deposits form extensive confining units between the unconfined areas, and the water-resource potential of confined aquifers is largely untested. Recharge, or replenishment, of these aquifers is dependent not only on infiltration of precipitation directly on unconfined aquifers, but perhaps more so from precipitation that falls in adjacent upland areas. Surface runoff and shallow groundwater from the valley walls flow downslope and recharge valley aquifers. Tributary streams that drain upland areas lose flow as they enter main valleys on permeable alluvial fans. This infiltrating water also recharges valley aquifers. Current (2012) use of water resources in the area is primarily through domestic wells, most of which are completed in fractured bedrock in upland areas. A few villages in the Susquehanna River valley have supply wells that draw water from beneath alluvial fans and near the Susquehanna River, which is a large potential source of water from induced infiltration.

Anticipating Central Asian Water Stress: Variation in River Flow Dependency on Melt Waters from Alpine to Plains in the Remote Tien Shan Range, Kyrgyzstan Using a Rapid Hydro Assessment Methodology

NASA Astrophysics Data System (ADS)

Hill, A. F.; Wilson, A. M.; Williams, M. W.

2016-12-01

The future of mountain water resources in High Asia is of high interest to water managers, development organizations and policy makers given large populations downstream reliant on snow and ice sourced river flow. Together with historical and cultural divides among ex-Soviet republics, a lack of central water management following the Soviet break-up has led to water stress as trans-boundary waters weave through and along borders. New upstream hydropower development, a thirsty downstream agricultural sector and a shrinking Aral Sea has led to increasing tension in the region. Despite these pressures and in contrast to eastern High Asia's Himalayan basins (Ganges, Brahmaputra), little attention has been given to western High Asia draining the Pamir and Tien Shan ranges (Syr Darya and Amu Darya basins) to better understand the hydrology of this vast and remote area. Difficult access and challenging terrain exacerbate challenges to working in this remote mountain region. As part of the Contributions to High Asia Runoff from Ice and Snow (CHARIS) project, we asked how does river flow source water composition change over an alpine-to-plains domain of Kyrgyzstan's Naryn River in the Syr Darya basin? In addition, what may the future hold for river flow in Central Asia given the differing responses of snow and ice to climate changes? Utilizing a Rapid Hydrologic Assessment methodology including a suite of pre-field mapping techniques we collected in situ water chemistry data at targeted, remote mountain sites over 450km of the Naryn River over an elevation gradient from glacial headwaters to the lower lying areas - places where people, hydropower and agriculture utilize water. Chemical and isotope tracers were used to separate stream flow to understand relative dependency on melt waters as the river moves downstream from glaciers and snow covered areas. This case study demonstrates a technique to acquire field data over large scales in remote regions that facilitates regional basin wide hydrologic characterization. The arid hydro-climatology of the Naryn basin also serves as an important comparison to the monsoon-dominated eastern Himalaya studies, thereby providing bookends to anticipating possible hydrologic futures across the High Asian mountain arc.

Discharge and water chemistry of High Arctic rivers in NW Greenland (76° N, 68° W)

NASA Astrophysics Data System (ADS)

Hagedorn, B.; Sletten, R. S.; Vigna, A. C.; Hallet, B.

2004-12-01

The volume, temperature, and quality of freshwater runoff from high latitude areas ultimately affect sensitive components of polar oceans, including water stratification, nutrient cycling, and formation of deepwater currents. Freshwater is conveyed from Greenland to the ocean from a multitude of medium-sized rivers for which little is known about discharge and water characteristics. River runoff together with microclimate and soil processes were recorded in a typical high Arctic area in NW Greenland where complete climate records from pre-1978 to the present indicate increases in mean annual air temperature from -12.0° C to -10.7° C and precipitation from 65 mm to 120 mm water equivalent between 1993 and 2002. The study will improve understanding of the interaction between climate, landscape processes, and river runoff. The study site extends from the western edge of the Greenland Ice Sheet to Baffin Bay; it covers an area ranging between 10-20 km E-W and 10-15 km N-S, and the elevations reach 700 m. It is a typical high Arctic environment with sparse vegetation and pervasive active patterned ground. Most of the area is covered by glacial drift that resembles the underlying sedimentary and igneous Archean and Proterozoic bedrock. To address how seasonal weather patterns and landscape processes affect runoff and water quality, as well as to examine weathering and carbon budgets in the drainage, we monitor water discharge and suspended load, water temperature, water chemistry (pH, dissolved ions, dissolved organic and inorganic carbon) of three rivers. Two of these rivers originate as melt water runoff from the Greenland Ice Sheet. The third stream is fed by local snowmelt and summer rain events. In addition, climate data along with soil moisture and temperature are recorded with automated stations at two locations. The potential sources of river water are thawing permafrost, local snowmelt, rain, and melting of glacial ice that all have distinct isotopic signatures (δ D and δ 18O). Stable isotopes therefore, are used to separate the hydrograph into these sources to help us relate discharge pattern and water quality to climate (precipitation, temperature) and landscape processes (thawing of permafrost, weathering, decomposition of organic matter). This presentation focuses on first data set collected from June to September 2004.

Ice sculpture in the Martian outflow channels

NASA Technical Reports Server (NTRS)

Lucchitta, B. K.

1982-01-01

Viking Orbiter and terrestrial satellite images are examined at similar resolution to compare features of the Martian outflow channels with features produced by the movement of ice on earth, and many resemblances are found. These include the anastomoses, sinuosities, and U-shaped cross profiles of valleys; hanging valleys; linear scour marks on valley walls; grooves and ridges on valley floors; and the streamlining of bedrock highs. Attention is given to the question whether ice could have moved in the Martian environment. It is envisaged that springs or small catastrophic outbursts discharged fluids from structural outlets or chaotic terrains. These fluids built icings that may have grown into substantial masses and eventually flowed like glaciers down preexisting valleys. An alternative is that the fluids formed rivers or floods that in turn formed ice jams and consolidated into icy masses in places where obstacles blocked their flow.

18. View southeast, west end of spillway, shows cribbing and ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

18. View southeast, west end of spillway, shows cribbing and metal ice shield - Sewall's Falls Hydroelectric Facility, East end of Second Street spanning Merrimack River, Concord, Merrimack County, NH

Microwave signatures of snow and fresh water ice

NASA Technical Reports Server (NTRS)

Schmugge, T.; Wilheit, T. T.; Gloersen, P.; Meier, M. F.; Frank, D.; Dirmhirn, I.

1973-01-01

During March of 1971, the NASA Convair 990 Airborne Observatory carrying microwave radiometers in the wavelength range 0.8 to 21 cm was flown over dry snow with different substrata: Lake ice at Bear Lake in Utah; wet soil in the Yampa River Valley near Steamboat Springs, Colorado; and glacier ice, firm and wet snow on the South Cascade Glacier in Washington. The data presented indicate that the transparency of the snow cover is a function of wavelength. False-color images of microwave brightness temperatures obtained from a scanning radiometer operating at a wavelength of 1.55 cm demonstrate the capability of scanning radiometers for mapping snowfields.

Radar and infrared remote sensing of terrain, water resources, arctic sea ice, and agriculture

NASA Technical Reports Server (NTRS)

Biggs, A. W.

1983-01-01

Radar range measurements, basic waveforms of radar systems, and radar displays are initially described. These are followed by backscatter from several types of terrain and vegetation as a function of frequency and grazing angle. Analytical models for this backscatter include the facet models of radar return, with range-angle, velocity-range, velocity-angle, range, velocity, and angular only discriminations. Several side-looking airborne radar geometries are presented. Radar images of Arctic sea ice, fresh water lake ice, cloud-covered terrain, and related areas are presented to identify applications of radar imagery. Volume scatter models are applied to radar imagery from alpine snowfields. Short pulse ice thickness radar for subsurface probes is discussed in fresh-water ice and sea ice detection. Infrared scanners, including multispectral, are described. Diffusion of cold water into a river, Arctic sea ice, power plant discharges, volcanic heat, and related areas are presented in thermal imagery. Multispectral radar and infrared imagery are discussed, with comparisons of photographic, infrared, and radar imagery of the same terrain or subjects.

Subglacial drainage patterns of Devon Island, Canada: detailed comparison of rivers and subglacial meltwater channels

NASA Astrophysics Data System (ADS)

Grau Galofre, Anna; Jellinek, A. Mark; Osinski, Gordon R.; Zanetti, Michael; Kukko, Antero

2018-04-01

Subglacial meltwater channels (N-channels) are attributed to erosion by meltwater in subglacial conduits. They exert a major control on meltwater accumulation at the base of ice sheets, serving as drainage pathways and modifying ice flow rates. The study of exposed relict subglacial channels offers a unique opportunity to characterize the geomorphologic fingerprint of subglacial erosion as well as study the structure and characteristics of ice sheet drainage systems. In this study we present detailed field and remote sensing observations of exposed subglacial meltwater channels in excellent preservation state on Devon Island (Canadian Arctic Archipelago). We characterize channel cross section, longitudinal profiles, and network morphologies and establish the spatial extent and distinctive characteristics of subglacial drainage systems. We use field-based GPS measurements of subglacial channel longitudinal profiles, along with stereo imagery-derived digital surface models (DSMs), and novel kinematic portable lidar data to establish a detailed characterization of subglacial channels in our field study area, including their distinction from rivers and other meltwater drainage systems. Subglacial channels typically cluster in groups of ˜ 10 channels and are oriented perpendicular to active or former ice margins. Although their overall direction generally follows topographic gradients, channels can be oblique to topographic gradients and have undulating longitudinal profiles. We also observe that the width of first-order tributaries is 1 to 2 orders of magnitude larger than in Devon Island river systems and approximately constant. Furthermore, our findings are consistent with theoretical expectations drawn from analyses of flow driven by gradients in effective water pressure related to variations in ice thickness. Our field and remote sensing observations represent the first high-resolution study of the subglacial geomorphology of the high Arctic, and provide quantitative and qualitative descriptions of subglacial channels that revisit well-established field identification guidelines. Distinguishing subglacial channels in topographic data is critical for understanding the emergence, geometry, and extent of channelized meltwater systems and their role in ice sheet drainage. The final aim of this study is to facilitate the identification of subglacial channel networks throughout the globe by using remote sensing techniques, which will improve the detection of these systems and help to build understanding of the underlying mechanics of subglacial channelized drainage.

Geological setting control of flood dynamics in lowland rivers (Poland).

PubMed

Wierzbicki, Grzegorz; Ostrowski, Piotr; Falkowski, Tomasz; Mazgajski, Michał

2018-04-27

We aim to answer a question: how does the geological setting affect flood dynamics in lowland alluvial rivers? The study area covers three river reaches: not trained, relatively large on the European scale, flowing in broad valleys cut in the landscape of old glacial plains. We focus on the locations where levees [both: a) natural or b) artificial] were breached during flood. In these locations we identify (1) the erosional traces of flood (crevasse channels) on the floodplain displayed on DEM derived from ALS LIDAR. In the main river channel, we perform drillings in order to measure the depth of the suballuvial surface and to locate (2) the protrusions of bedrock resistant to erosion. We juxtapose on one map: (1) the floodplain geomorphology with (2) the geological data from the river channel. The results from each of the three study reaches are presented on maps prepared in the same manner in order to enable a comparison of the regularities of fluvial processes written in (1) the landscape and driven by (2) the geological setting. These processes act in different river reaches: (a) not embanked and dominated by ice jam floods, (b) embanked and dominated by rainfall and ice jam floods. We also analyse hydrological data to present hydrodynamic descriptions of the flood. Our principal results indicate similarity of (1) distinctive erosional patterns and (2) specific geological features in all three study reaches. We draw the conclusion: protrusions of suballuvial bedrock control the flood dynamics in alluvial rivers. It happens in both types of rivers. In areas where the floodplain remains natural, the river inundates freely during every flood. In other areas the floodplain has been reclaimed by humans who constructed an artificial levee system, which protects the flood-prone area from inundation, until levee breach occurs. Copyright © 2018 Elsevier B.V. All rights reserved.

Suspension freezing of bottom sediment and biota in the Northwest Passage and implications for Arctic Ocean sedimentation

USGS Publications Warehouse

Reimnitz, E.; Marincovich, L.; McCormick, M.; Briggs, W.M.

1992-01-01

No evidence was seen for entrainment by bottom adfreezing, bluff slumping, river flooding, dragging ice keels, or significant eolian transport from land to sea. Muddy sediment with pebbles and cobbles, algae with holdfasts, ostracodes with appendages, and well-preserved mollusks and sea urchins were collected from two sites in a 50 km long stretch of turbid ice. These materials indicate that suspension freezing reaching to a water depth of 25-30 m during the previous fall was responsible for entrainment. This mechanism requires rapid ice formation in open, shallow water during a freezing storm, when the ocean becomes supercooled, and frazil and anchor ice attach to and ultimately lift sediment and living organisms to the sea surface. -from Authors

Airborne profiling of ice thickness using a short pulse radar

NASA Technical Reports Server (NTRS)

Vickers, R. S.; Heighway, J. E.; Gedney, R. T.

1973-01-01

This paper describes helicopter-borne measurements of ice thickness in Lake Superior, Lake St. Clair, and the St. Clair river as part of NASA's program to develop an ice information system. The profiler described is a high resolution, nonimaging, short pulse radar, operating at a carrier frequency of 2.7 GHz. The system can resolve reflective surfaces separated by as little as 10 cm and permits measurement of the distance between resolvable surfaces with an accuracy of about 1 cm. Data samples are given for measurements both in a static (helicopter hovering), and a traverse mode. Ground truth measurements taken by an ice auger team traveling with the helicopter are compared with the remotely sensed data and the accuracy of the profiler is discussed based on these measurements.

Glacier retreat and projected river regime changes in the hydrologically highly-coupled Virkisjökull catchment, Iceland

NASA Astrophysics Data System (ADS)

Flett, Verity; Kirkbride, Martin; Black, Andrew; Everest, Jez; MacDonald, Alan

2016-04-01

Virkisjökull, an outlet glacier of the Oræfajökull icecap in SE Iceland, currently has 60% glacier cover, though this is reducing due to glacier retreat. Intensive monitoring over the last 4 years includes measurement of measuring ice ablation, proglacial discharge, dye-tracing of flow pathways, and deployment of three automatic weather stations at altitudes up to 880 m. These data calibrate a distributed hydrological model (WaSIM) to project potential river regime during stages of glacier retreat. Results show: (1) glacier hypsometry sensitises the catchment to a disproportionately rapid increase in runoff as the snowline rises onto a gentle ice cap resulting in in a potential annual increase in river discharge of up to 37% (2) a dominantly channelized glacial drainage system in all seasons with a rapid runoff response to melt: englacial flow of 0.58 m s-1 is comparable to the proglacial river velocity; and (3) longer-term, reduced glacier cover and snow storage will lead to a discharge regime dominated by short-term precipitation events in all seasons, and a reduced influence of the seasonal meltwater discharge peak. The study demonstrates the importance of glacier hypsometry above the present ELA as an influence on catchment hydrological response to potential climate warming.

Comparative Application of Dimensionless Bankfull Hydraulic Relations for Earth and Titan

NASA Astrophysics Data System (ADS)

Parker, G.

2005-12-01

Recent evidence from the Huygens Probe of the Cassini Mission suggests that Titan, a satellite of Saturn, has rivers of flowing liquid methane which transport disaggregated crustal sediment in the form of ice. Surface images from the Huygens Probe show gravel-sized ice clasts that appear to be well-rounded by fluvial processes. If river morphodynamics on Earth is truly understood at a physical level, then relations that provide reasonable results on Earth ought to provide similarly reasonable results on Titan. These basic relations should be expressed in terms of dimensionless variabes. At least three dimensioned parameters that would be used to form the relevant dimensionless variables can be expected to vary notably between Earth and Titan. These are a) the acceleration of gravity, the kinematic viscosity of the flowing fluid and the submerged specific gravity of the sediment. Dimensionless relations for the threshold of motion, the threshold of significant suspension and bankfull hydraulic geometry that are known to work on Earth are used to predict features of rivers on Titan. Wildcards that make the predictions tentative include the formation of hydrocarbons on Titan that might add a kind of cohesivity not encountered on Earth and a freeze-thaw process of methane that might not be analogous to freeze-thaw processes in high-latitude rivers on Earth.

Lena River Delta and East Siberian Sea

NASA Technical Reports Server (NTRS)

2002-01-01

The winter sea ice in the east Siberian Sea is looking a bit like a cracked windshield in these true-color Moderate Resolution Imaging Spectroradiometer (MODIS) images from June 16 and 23, 2002. North of the thawing tundra, the sea ice takes on its cracked, bright blue appearance as it thins, which allows the reflection of the water to show through. Numerous still-frozen lakes dot the tundra. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

Studies of the inner shelf and coastal sedimentation environment of the Beaufort Sea from ERTS-1

NASA Technical Reports Server (NTRS)

Reimnitz, E. (Principal Investigator); Barnes, P. W.

1973-01-01

The author has identified the following significant results. Northward flowing rivers of Alaska inundate extensive areas of sea ice during spring breakup. This process has been studied under the ERTS-1 program. Drainage of large volumes of fresh water through the ice at holes and cracks (strudel) causes scour depressions, over 4 m deep, and up to 20 m across in the sea floor below. Strudel scours occur within 30 km of river mouths, generally in areas where ERTS-1 imagery shows less potential for drifting ice to scour the bottom than elsewhere. The shapes and distribution patterns of strudel scours correspond with those of strudel seen in the ice canopy. Densities of scours are highest in the inner areas of overlfow. But strudel scours also occur outside of overflow areas mapped during the last several years. These must be very old. One strudel scour investigated by diving is surrounded by a rim, has vertical walls exposing a tundra horizon, and terminates at a gravel layer 4 m below the lagoon floor. Another terminates at a semi-consolidated layer of silty clay. The gravel and silty clay are pre-Holocene deposits. Mixing of Holocene marine with older sediments by vertical strudel flow causes great variability in sediment types over small areas. These observations complicate interpretation of shallow water deposits of cold climates.

Transport and transformation of riverine neodymium isotope and rare earth element signatures in high latitude estuaries: A case study from the Laptev Sea

NASA Astrophysics Data System (ADS)

Laukert, Georgi; Frank, Martin; Bauch, Dorothea; Hathorne, Ed C.; Gutjahr, Marcus; Janout, Markus; Hölemann, Jens

2017-11-01

Marine neodymium (Nd) isotope and rare earth element (REE) compositions are valuable tracers for present and past ocean circulation and continental inputs. Yet their supply via high latitude estuaries is largely unknown. Here we present a comprehensive dissolved Nd isotope (expressed as εNd values) and REE data set together with seawater stable oxygen isotope (δ18O) compositions of samples from the Laptev Sea recovered in two Arctic summers and one winter. The Laptev Sea is a shallow Siberian Shelf sea characterized by extensive river-runoff, sea-ice production and ice transport into the Arctic Ocean. The large variability in εNd (-6 to -17), REE concentrations (16 to 600 pmol/kg for Nd) and REE patterns is controlled by freshwater supply from distinct riverine sources and open ocean Arctic Atlantic Water. Strikingly and contrary to expectations, except for cerium no evidence for significant release of REEs from particulate phases is found, which is attributed to low amounts of suspended particulate matter and high dissolved organic carbon concentrations present in the contributing rivers. Essentially all shelf waters are depleted in light (L)REEs, while the distribution of the heavy REEs shows a deficiency at the surface and a pronounced excess in the bottom layer. This distribution is consistent with REE removal through coagulation of riverine nanoparticles and colloids starting at salinities near 10 and resulting in a drop of all REE concentrations by ∼30%. With increasing salinity preferential LREE removal is observable reaching ∼75% for Nd at a salinity of 34. Although the delayed onset of dissolved REE removal contrasts with most previous observations from other estuarine environments, it agrees remarkably well with results from recent experiments simulating estuarine mixing of seawater with organic-rich river waters. In addition, melting and formation of sea ice leads to further REE depletion at the surface and strong REE enrichment near the shelf bottom as a function of ice melting and brine transfer, respectively. The ice-related processes significantly affect the distribution of dissolved REEs in high-latitude estuaries and likely also similarly contribute to the redistribution of other dissolved seawater constituents.

Development of Conceptual Designs for the Prevention of Ice Formation in the Proposed Maple River Aqueduct

DTIC Science & Technology

2014-09-18

USA 1907 Reinforced concrete 50 × 6 × up to 350 ft various heights 35 ft 1675 2244 7 creeks and the Green River/ Hennepin Canal Solid...2 1 1 2 2e xs f U Uh L S C g g α α = + − (4) where Lxs = the distance between cross sections, g = the acceleration of gravity, α1 and α2 = the

Transnational Sea-Ice Transport in a Warmer, More Mobile Arctic

NASA Astrophysics Data System (ADS)

Newton, R.; Tremblay, B.; Pfirman, S. L.; DeRepentigny, P.

2015-12-01

As the Arctic sea ice thins, summer ice continues to shrink in its area, and multi-year ice becomes rarer, winter ice is not disappearing from the Arctic Basin. Rather, it is ever more dominated by first year ice. And each summer, as the total coverage withdraws, the first year ice is able travel faster and farther, carrying any ice-rafted material with it. Micro-organisms, sediments, pollutants and river runoff all move across the Arctic each summer and are deposited hundreds of kilometers from their origins. Analyzing Arctic sea ice drift patterns in the context of the exclusive economic zones (EEZs) of the Arctic nations raises concerns about the changing fate of "alien" ice which forms within one country's EEZ, then drifts and melts in another country's EEZ. We have developed a new data set from satellite-based ice-drift data that allows us to track groups of ice "pixels" forward from their origin to their destination, or backwards from their melting location to their point of formation. The software has been integrated with model output to extend the tracking of sea ice to include climate projections. Results indicate, for example, that Russian sea ice dominates "imports" to the EEZ of Norway, as expected, but with increasing ice mobility it is also is exported into the EEZs of other countries, including Canada and the United States. Regions of potential conflict are identified, including several national borders with extensive and/or changing transboundary sea ice transport. These data are a starting point for discussion of transborder questions raised by "alien" ice and the material it may import from one nation's EEZ to another's.

Numerical model of frazil ice and suspended sediment concentrations and formation of sediment laden ice in the Kara Sea

USGS Publications Warehouse

Sherwood, C.R.

2000-01-01

A one-dimensional (vertical) numerical model of currents, mixing, frazil ice concentration, and suspended sediment concentration has been developed and applied in the shallow southeastern Kara Sea. The objective of the calculations is to determine whether conditions suitable for turbid ice formation can occur during times of rapid cooling and wind- and wave-induced sediment resuspension. Although the model uses a simplistic approach to ice particles and neglects ice-sediment interactions, the results for low-stratification, shallow (∼20-m) freeze-up conditions indicate that the coconcentrations of frazil ice and suspended sediment in the water column are similar to observed concentrations of sediment in turbid ice. This suggests that wave-induced sediment resuspension is a viable mechanism for turbid ice formation, and enrichment mechanisms proposed to explain the high concentrations of sediment in turbid ice relative to sediment concentrations in underlying water may not be necessary in energetic conditions. However, salinity stratification found near the Ob' and Yenisey Rivers damps mixing between ice-laden surface water and sediment-laden bottom water and probably limits incorporation of resuspended sediment into turbid ice until prolonged or repeated wind events mix away the stratification. Sensitivity analyses indicate that shallow (≤20 m), unstratified waters with fine bottom sediment (settling speeds of ∼1 mm s−1 or less) and long open water fetches (>25 km) are ideal conditions for resuspension.

Sea ice and surface water circulation, Alaskan continental shelf

NASA Technical Reports Server (NTRS)

Wright, F. F. (Principal Investigator); Sharma, G. D.; Burns, J. J.

1973-01-01

The author has identified the following significant results. Sediments contributed by the Copper River in the Gulf of Alaska are carried westward along the shore as a distinct plume. Oceanic water relatively poor in suspended material appears to intrude near Montague Island, and turbid water between Middleton Island and Kayak Island is the result of Ekman between transport. An anticlockwise surface water circulation is observed in this region. Ground truth data indicate striking similarity with ERTS-1 imagery obtained on October 12, 1972. Observations of ERTS-1 imagery reveal that various characteristics and distribution of sea ice in the Arctic Ocean can be easily studied. Formation of different types of sea ice and their movement is quite discrenible. Sea ice moves parallel to the cost in near shore areas and to the northerly direction away from the coast.

Recurrence of July Joklhlaup Flooding in the Mendenhall Glacier Watershed is Driven by Record Breaking Precipitation, Regional Warming, and the Collapse of a Tributary Glacier near Juneau, AK USA

NASA Astrophysics Data System (ADS)

Connor, C. L.; Hood, E. W.; Hekkers, M.; Kugler, N.

2012-12-01

During the summer of 2012, the U.S. Weather Service Station in Juneau, AK (located at 24 m asl and near the 1769 Little Ice Age terminal moraine of the Mendenhall Glacier), recorded the lowest daily average maximum May to July temperature of 12.2oC (54.9o F), [2.4oC (-4.4o F) below normal] over 69 years of record. This year's summer temperature anomalies contrast with an overall Juneau trend of warming 1.6oC, (2.88oF) since 1943. The rising temperature parallels glacier ice reduction by thinning at a rate of >2m/yr and ice terminus retreat of 3.86 km between 1909 and 2011. Mendenhall Lake which began forming after 1930 has increased from 3.9 to 4.2 km2 in area and 0.05-0.09 km3 in volume between 2000 and 2011 as the glacier retreated. Since 2000, maximum lake depth has increased from 70 to 90m at the lakefront terminus. Northeast and 3.6 km above the glacier terminus, the Suicide Basin Ice Fall no longer flows into Mendenhall glacier, which has created a large ice-marginal basin that can hold a substantial volume of water. Once rare, mid-summer flooding has recently been caused by abrupt subglacial releases of rain water stored in this tributary cirque basin. Large water volumes are lifting and flowing under the surviving main trunk of the Mendenhall Glacier. These glacial outburst floods have raised Mendenhall Lake levels and increased discharge into the outlet Mendenhall River. On July 19-22, 2011 an estimated subglacial discharge of 37,000,000 m3 (1,306,642,650 ft3) raised proglacial Mendenhall Lake level by 1.67m (5.5 ft) and increased discharge on the Mendenhall River from 79 to 453 m3/s (2,800-16,000 f3/s). Temperature sensor strings on buoys in the lake have captured lake bottom (-49m) temperature drops of ~ 1oC as cold waves of subglacially released water move at depth from the glacier base into the river. Lake temperature data from summer 2012 sensors will be presented at this meeting. During summer 2012, a repeat joklhlaup event occurred July 3-6, rising lake level from 1.37m to 2.54m (4.5-8.35 feet), just below flood stage at 2.74m (9 ft) and increased river discharge from 58 to 259 m3/sec (1,900 to 9,150 ft3/s). Over the 46 years of record of Mendenhall River hydrologic monitoring by the USGS Water Resources Division, only 5 events of mid-summer elevated water stages have been recorded with two of them in 2011 and 2012.

Observations of geese foraging for clam shells during spring on the Yukon-Kuskokwim Delta, Alaska

USGS Publications Warehouse

Flint, Paul L.; Fowler, Ada C.; Bottitta, Grace E.; Schamber, Jason L.

1998-01-01

We studied the behavior of geese on exposed river ice during spring on the Yukon-Kuskokwim Delta. The predominant behavior while on the ice for both sexes was foraging; however, females foraged more than males. Visual inspection of the ice revealed no potential plant or animal food items. However, numerous small (<20 mm) clam shells (Macoma balthica) and pieces of shell were noted. It appeared that geese were foraging on empty clam shells. This potential source of calcium was available to breeding geese just prior to egg formation and geese likely stored this calcium in the form of medullary bone for use during egg formation.

Glacier-derived permafrost ground ice, Bylot Island, Nunavut

NASA Astrophysics Data System (ADS)

Coulombe, S.; Fortier, D.; Lacelle, D.; Godin, E.; Veillette, A.

2014-12-01

Massive icy bodies are important components of permafrost geosystems. In situ freezing of water in the ground by ice-segregation processes forms most of these icy bodies. Other hypotheses for the origin of massive ice include the burial of ice (e.g. glacier, snow, lake, river, sea). The analysis of ground-ice characteristics can give numerous clues about the geomorphologic processes and the thermal conditions at the time when permafrost developed. Massive underground ice therefore shows a great potential as a natural archive of the earth's past climate. Identifying the origin of massive ice is a challenge for permafrost science since the different types of massive ice remain difficult to distinguish on the sole basis of field observations. There is actually no clear method to accurately assess the origin of massive ice and identification criteria need to be defined. The present study uses physico-chemical techniques to characterize buried glacier ice observed on Bylot Island, Nunavut. Combined to the analysis of cryostratigraphy, massive-ice cores crystallography and high-resolution imagery of the internal structure of the ice cores were obtained using micro-computed tomography techniques. These techniques are well suited for detailed descriptions (shape, size, orientation) of crystals, gas inclusions and sediment inclusions. Oxygen and hydrogen isotopes ratios of massive-ice cores were also obtained using common equilibrium technique. Preliminary results suggest the occurrence of two types of buried massive-ice of glacial origin similar to those found on contemporary glaciers: 1) Englacial ice: clear to whitish ice, with large crystals (cm) and abundant gas bubbles at crystal intersections; 2) Basal glacier ice: ice-rich, banded, micro-suspended to suspended cryostructures and ice-rich lenticular to layered cryostructures, with small ice crystals (mm) and a few disseminated gas bubbles. Glacier-derived permafrost contains antegenetic ice, which is ice that predates the aggradation of the permafrost. Remnants of glacier ice represent unique environmental archives and offer the possibility to reconstruct climate anterior to the formation of permafrost.

12. VIEW SHOWING CCC CREWS FREEING FLOOD GATES AT DAM ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. VIEW SHOWING CCC CREWS FREEING FLOOD GATES AT DAM 326 OF ICE TO PREVENT DAMAGE TO STRUCTURE - J. Clark Salyer National Wildlife Refuge, Dam 326, Along Lower Souris River, Kramer, Bottineau County, ND

A New Unusual Ice-induced Sedimentary Structure: the Silt Mushroom

PubMed Central

Jianhua, Zhong; Liangtian, Ni; Ningliang, Sun; Chuang, Liu; Bing, Hao; Mengchun, Cao; xin, Chen; Ke, Luo; Shengxin, Liu; Leitong, Huang; Guanqun, Yang; Shaojie, Wang; Feifei, Su; Xuejing, He; Yanqiu, Xue

2016-01-01

Upon channel bars or point bars within the lows of the Yellow River, a new sedimentary structure, named ‘silt mushroom’, has been observed. The process of their formation is interpreted to be via the ice process. The name, the silt mushroom comes from their figurative form. This is because they look somewhat similar to mushroom’s in size and shape; being in the range of 1 to 10 cm in diameter, with the medium 3–5 cm, and on average 10 cm in height, occuring generally in groups, and occasionally in isolation in relatively soft silt. They develop in the transition from winter to spring, and are convincingly related to ice processes. Ice-induced silt mushrooms are best examined in association with the many other newly discovered ice-induced sedimentary structures (over 20 kinds). Clearly, up to now, ice processes have been significantly underestimated. With the substantial discovery of the ice-induced silt mushroom, it opens up new questions. This is because its structure mirrors the same sedimentary structures found in rocks, questioning their genesis, and sedimentary environment analysis. This achievement is significant not only in sedimentology, but also in palaeogeography, palaeoclimate, geological engineering, hydraulics and fluviology. PMID:27833155

Remote sensing of ocean color in the Arctic

NASA Technical Reports Server (NTRS)

Maynard, N. G.

1988-01-01

The main objectives of the research are: to increase the understanding of biological production (and carbon fluxes) along the ice edge, in frontal regions, and in open water areas of the Arctic and the physical factors controlling that production through the use of satellite and aircraft remote sensing techniques; and to develop relationships between measured radiances from the Multichannel Aircraft Radiometer System (MARS) and the bio-optical properties of the water in the Arctic and adjacent seas. Several recent Coastal Zone Color Scanner (CZCS) studies in the Arctic have shown that, despite constraints imposed by cloud cover, satellite ocean color is a useful means of studying mesoscale physical and biological oceanographic phenomena at high latitudes. The imagery has provided detailed information on ice edge and frontal processes such as spring breakup and retreat of the ice edge, influence of ice on ice effects of stratification on phytoplankton production, river sediment transport, effects of spring runoff, water mass boundaries, circulation patterns, and eddy formation in Icelandic waters and in the Greenland, Barents, Norwegian, and Bering Seas.

Water survey of Canada: Application for use of ERTS-A for retransmission of water resources data

NASA Technical Reports Server (NTRS)

Halliday, R. A. (Principal Investigator); Reid, I. A.

1974-01-01

The author has identified the following significant results. The fact that water resources data can be retransmitted from remote areas of Canada by polar orbiting spacecraft to users in population centers on a near real time basis reliably, accurately, and at relative low cost continues to be demonstrated. Over 60,000 transmissions from the nine data collection platforms installed at Water Survey of Canada gauging stations have been received. The stage and ice-out data retransmitted via ERTS-1 have been plotted on a chart record produced by a water stage servo-manometer installed on the Albany River. The stage increased smoothly until shortly after noon on May 19, 1974. During this time the indicator showed that the ice surface was intact. The stage then dropped sharply and the indicator read that the ice was out. The erratic chart trace after that was consistent with the assumption that the ice surface had broken up and that some short duration jams of broken ice were occurring.

Annual Report Fiscal Year 2003 of the Secretary of the Army on Civil Works Activities (1 October 2004 - 30 September 2005)

DTIC Science & Technology

2006-08-25

the glaciers that covered the Great Lakes region during the last ice age. IMPROVEMENTS Navigation Page 1. Alpena Harbor, MI...21-85 NAVIGATION 1. ALPENA HARBOR, MI Location. At mouth of Thunder Bay River which empties into Thunder Bay, Lake Huron...Harbor is 100 miles southeast of Cheboygan Harbor, MI. River has its source in Montmorency and Alpena Counties, MI. (See NOAA Nautical Chart

Examining Differences in Arctic and Antarctic Sea Ice Change

NASA Astrophysics Data System (ADS)

Nghiem, S. V.; Rigor, I. G.; Clemente-Colon, P.; Neumann, G.; Li, P.

2015-12-01

The paradox of the rapid reduction of Arctic sea ice versus the stability (or slight increase) of Antarctic sea ice remains a challenge in the cryospheric science research community. Here we start by reviewing a number of explanations that have been suggested by different researchers and authors. One suggestion is that stratospheric ozone depletion may affect atmospheric circulation and wind patterns such as the Southern Annular Mode, and thereby sustaining the Antarctic sea ice cover. The reduction of salinity and density in the near-surface layer may weaken the convective mixing of cold and warmer waters, and thus maintaining regions of no warming around the Antarctic. A decrease in sea ice growth may reduce salt rejection and upper-ocean density to enhance thermohalocline stratification, and thus supporting Antarctic sea ice production. Melt water from Antarctic ice shelves collects in a cool and fresh surface layer to shield the surface ocean from the warmer deeper waters, and thus leading to an expansion of Antarctic sea ice. Also, wind effects may positively contribute to Antarctic sea ice growth. Moreover, Antarctica lacks of additional heat sources such as warm river discharge to melt sea ice as opposed to the case in the Arctic. Despite of these suggested explanations, factors that can consistently and persistently maintains the stability of sea ice still need to be identified for the Antarctic, which are opposed to factors that help accelerate sea ice loss in the Arctic. In this respect, using decadal observations from multiple satellite datasets, we examine differences in sea ice properties and distributions, together with dynamic and thermodynamic processes and interactions with land, ocean, and atmosphere, causing differences in Arctic and Antarctic sea ice change to contribute to resolving the Arctic-Antarctic sea ice paradox.

[Diurnal variations of grassland evapotranspiration over different periods in the Pailugou basin in the upper reach of the Heihe River, Northwest China.

PubMed

Wang, Zhong Fu; Zhang, Lan Hui; Wang, Yi Bo; He, Chan Sheng

2016-11-18

Evapotranspiration (ET) is an important component of water cycle, but its measurement in high altitude mountainous region is quite difficult, resulting in the poor understanding of the temporal and spatial variations of actual ET in high altitude mountainous region. In this paper, a weighing lysimeter was used to measure the hourly ET in a grassland in the Pailugou basin in the upper reach of the Heihe River, Northwest China. Based on the measured data, diurnal variations of grassland ET over different periods were analyzed. Results indicated that snow and ice sublimation appeared during the freezing period, with a very different diurnal variation pattern compared with other three periods. During the period without sunshine, the amount of snow and ice sublimation was nearly constant. When the highest global radiation and lowest relative humidity appeared in the same period, the amount of snow and ice sublimation increased a little. The early growth period was a period when snow and ice started to melt, during which snowmelt evaporation and soil evaporation occurred at the same time. The growth period had the highest ET rate. Due to continuous rainfall events, maximum and minimum ET values appeared at the same hour. ET in the late growth period mainly came from soil evaporation, producing 3 peaks in diurnal variation, which was different from only one peak in both the early growth period and the growth period.

Deglacial-Holocene short-term variability in sea-ice distribution on the Eurasian shelf (Arctic Ocean) - An IP25 biomarker reconstruction.

NASA Astrophysics Data System (ADS)

Hörner, Tanja; Stein, Ruediger; Fahl, Kirsten

2016-04-01

Four well-dated sediment cores from the Eurasian continental shelf, i.e., the Kara Sea (Cores BP99/07 and BP00/07) and Laptev Sea (Cores PS51/154 and PS51/159), were selected for high-resolution reconstruction of past Arctic environmental conditions during the deglacial-Holocene time interval. These marginal seas are strongly affected by the post-glacial sea-level rise of about 120m. The major focus of our study was the reconstruction of the paleo-sea-ice distribution as sea-ice plays a key role within the modern and past climate system. For reconstruction of paleo-sea ice, the sea-ice proxy IP25 in combination with open-water phytoplankton biomarkers was used (for approach see Belt et al., 2007; Müller et al., 2009, 2011). In addition, specific sterols were determined to reconstruct changes in river run-off and biological production. The post-glacial sea-level rise is especially reflected in prominent decrease in terrigenous biomarkers. Deglacial variations in sea-ice cover sustained for thousand of years, mostly following climatic changes like the Bølling/Allerød (14.7-12.9 ka), Younger Dryas (12.9-11.6 ka) and Holocene warm phase (10-8 ka). Superimposed on a (Late) Holocene cooling trend, short-term fluctuations in sea-ice cover (on centennial scale) are distinctly documented in the distal/off-shore Core BP00/07 from the Kara Sea, less pronounced in the proximal/near-shore Core PS99/07 and in the Laptev Sea cores. Interestingly, this short-term variability in sea-ice cover correlates quite well to changes in Siberian river run-off (e.g., Stein et al. 2004), pointing to a direct linkage between precipitation (atmospheric circulation) and sea-ice formation. References Belt, S.T., Massé, G., Rowland, S.J., Poulin, M., Michel, C., LeBlanc, B., 2007. A novel chemical fossil of palaeo sea ice: IP25. Organic Geochemistry 38, 16-27. Müller, J., Masse, G., Stein, R., Belt, S.T., 2009. Variability of sea-ice conditions in the Fram Strait over the past 30,000 years. Nature Geoscience 2, 772-776. Müller, J., Wagner, A., Fahl, K., Stein, R., Prange, M., Lohmann, G., 2011. Towards quantitative sea ice reconstructions in the northern North Atlantic: A combined biomarker and numerical modelling approach. Earth and Planetary Science Letters 306, 137-148. Stein, R., Steinke, T., Dittmers, K., Fahl, K., Kraus, M., Matthiessen, J., Niessen, F., Pirrung, M., Polyakova, Ye., Achoster, F., Fqtterer, D.K., 2004. Terrigenous sediment supply and paleoenvironment of the Holocene Kara Sea. Quaternary Science Reviews, 23, 485-1511.

Satellite imagery of the onset of streaming flow of ice streams C and D, West Antarctica

USGS Publications Warehouse

Hodge, S.M.; Doppelhammer, S.K.

1996-01-01

Five overlapping Landsat multispectral scanner satellite images of the interior of the West Antarctic ice sheet were enhanced with principal component analysis, high-pass filtering, and linear contrast stretching and merged into a mosaic by aligning surface features in the overlap areas. The mosaic was registered to geodetic coordinates, to an accuracy of about 1 km, using the five scene centers as control points. The onset of streaming flow of two tributaries of ice stream C and one tributary of ice stream D is visible in the mosaic. The onset appears to occur within a relatively short distance, less than the width of the ice stream, typically at a subglacial topographic feature such as a step or ridge. The ice streams extend farther up into the interior than previously mapped. Ice stream D starts about 150 km from the ice divide, at an altitude of about 1500 m, approximately halfway up the convex-upward dome shape of the interior ice sheet. Ice stream D is relatively much longer than ice stream C, possibly because ice stream D is currently active whereas ice stream C is currently inactive. The grounded portion of the West Antarctic ice sheet is perhaps best conceptualized as an ice sheet in which ice streams are embedded over most of its area, with slow moving ice converging into fast moving ice streams in a widely distributed pattern, much like that of streams and rivers in a hydrologic basin. A relic margin appears to parallel most of the south margin of the tributary of ice stream D, separated from the active shear margin by about 10 km or less for a distance of over 200 km. This means there is now evidence for recent changes having occurred in three of the five major ice streams which drain most of West Antarctica (B, C, and D), two of which (B and D) are currently active.

Observations in Nonurban Heat Islands.

NASA Astrophysics Data System (ADS)

Hogan, A. W.; Ferrick, M. G.

1998-02-01

The urban heat island is a well-known and well-described temperature anomaly, but other types of heat islands are also infrequently reported. A 10 km × 30 km data field containing more than 100 individual winter morning air temperature measurement points was examined for areas characteristically warmer than surrounding areas. The very small `downtown' of Hanover, New Hampshire, was found to be 1°-2°C warmer than nearby open areas at the same elevation. The same technique was applied to examine the morning air temperature within a nearby hamlet consisting of about 60 wooden buildings within an area less than 0.3 km2. The bulk of observations and observations stratified by snow and sky cover showed no systematic difference between hamlet air temperatures and those obtained in surrounding terrain. Morning air temperatures along a freezing river were measured and found to be systematically warmer than nearby air temperatures for several days, until a significant snowfall diminished the ice growth rate. A thorough examination of temperature profiles near the river showed that the increase in air temperature beneath the overnight inversion during this freezing period was proportional to the heat release resulting from river ice growth.

Alaska Glaciers and Rivers

NASA Technical Reports Server (NTRS)

2007-01-01

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image on October 7, 2007, showing the Alaska Mountains of south-central Alaska already coated with snow. Purple shadows hang in the lee of the peaks, giving the snow-clad land a crumpled appearance. White gives way to brown on the right side of the image where the mountains yield to the lower-elevation Susitna River Valley. The river itself cuts a silver, winding path through deep green forests and brown wetlands and tundra. Extending from the river valley, are smaller rivers that originated in the Alaska Mountains. The source of these rivers is evident in the image. Smooth white tongues of ice extend into the river valleys, the remnants of the glaciers that carved the valleys into the land. Most of the water flowing into the Gulf of Alaska from the Susitna River comes from these mountain glaciers. Glacier melt also feeds glacier lakes, only one of which is large enough to be visible in this image. Immediately left of the Kahiltna River, the aquamarine waters of Chelatna Lake stand out starkly against the brown and white landscape.

The Gamburtsev mountains and the origin and early evolution of the Antarctic Ice Sheet.

PubMed

Bo, Sun; Siegert, Martin J; Mudd, Simon M; Sugden, David; Fujita, Shuji; Xiangbin, Cui; Yunyun, Jiang; Xueyuan, Tang; Yuansheng, Li

2009-06-04

Ice-sheet development in Antarctica was a result of significant and rapid global climate change about 34 million years ago. Ice-sheet and climate modelling suggest reductions in atmospheric carbon dioxide (less than three times the pre-industrial level of 280 parts per million by volume) that, in conjunction with the development of the Antarctic Circumpolar Current, led to cooling and glaciation paced by changes in Earth's orbit. Based on the present subglacial topography, numerical models point to ice-sheet genesis on mountain massifs of Antarctica, including the Gamburtsev mountains at Dome A, the centre of the present ice sheet. Our lack of knowledge of the present-day topography of the Gamburtsev mountains means, however, that the nature of early glaciation and subsequent development of a continental-sized ice sheet are uncertain. Here we present radar information about the base of the ice at Dome A, revealing classic Alpine topography with pre-existing river valleys overdeepened by valley glaciers formed when the mean summer surface temperature was around 3 degrees C. This landscape is likely to have developed during the initial phases of Antarctic glaciation. According to Antarctic climate history (estimated from offshore sediment records) the Gamburtsev mountains are probably older than 34 million years and were the main centre for ice-sheet growth. Moreover, the landscape has most probably been preserved beneath the present ice sheet for around 14 million years.

Phylogeography of the Patagonian otter Lontra provocax: adaptive divergence to marine habitat or signature of southern glacial refugia?

PubMed Central

2011-01-01

Background A number of studies have described the extension of ice cover in western Patagonia during the Last Glacial Maximum, providing evidence of a complete cover of terrestrial habitat from 41°S to 56°S and two main refugia, one in south-eastern Tierra del Fuego and the other north of the Chiloé Island. However, recent evidence of high genetic diversity in Patagonian river species suggests the existence of aquatic refugia in this region. Here, we further test this hypothesis based on phylogeographic inferences from a semi-aquatic species that is a top predator of river and marine fauna, the huillín or Southern river otter (Lontra provocax). Results We examined mtDNA sequences of the control region, ND5 and Cytochrome-b (2151 bp in total) in 75 samples of L. provocax from 21 locations in river and marine habitats. Phylogenetic analysis illustrates two main divergent clades for L. provocax in continental freshwater habitat. A highly diverse clade was represented by haplotypes from the marine habitat of the Southern Fjords and Channels (SFC) region (43°38' to 53°08'S), whereas only one of these haplotypes was paraphyletic and associated with northern river haplotypes. Conclusions Our data support the hypothesis of the persistence of L. provocax in western Patagonia, south of the ice sheet limit, during last glacial maximum (41°S latitude). This limit also corresponds to a strong environmental change, which might have spurred L. provocax differentiation between the two environments. PMID:21356052

Active cycling of organic carbon in the central Arctic Ocean

NASA Astrophysics Data System (ADS)

Wheeler, Patricia A.; Gosselin, Michel; Sherr, Evelyn; Thibaultc, Delphine; Kirchman, David L.; Benner, Ronald; Whitledge, Terry E.

1996-04-01

THE notion of a barren central Arctic Ocean has been accepted since English's pioneering work1 on drifting ice-islands. The year-round presence of ice, a short photosynthetic season and low temperatures were thought to severely limit biological production1,2, although the paucity of data was often noted. Because primary production appeared to be low1,2, subsequent studies assumed that most organic carbon was either derived from river inputs or imported from adjacent continental-shelf regions3,4. Here we present shipboard measurements of biological produc-tion, biomass and organic carbon standing-stocks made during a cruise through the ice covering the central Arctic Ocean. Our results indicate that the central Arctic region is not a biological desert. Although it is less productive than oligotrophic ocean regions not covered by ice, it supports an active biological community which contributes to the cycling of organic carbon through dissolved and particulate pools.

Recent lake ice-out phenology within and among lake districts of Alaska, U.S.A.

USGS Publications Warehouse

Arp, Christopher D.; Jones, Benjamin M.; Grosse, Guido

2013-01-01

The timing of ice-out in high latitudes is a fundamental threshold for lake ecosystems and an indicator of climate change. In lake-rich regions, the loss of ice cover also plays a key role in landscape and climatic processes. Thus, there is a need to understand lake ice phenology at multiple scales. In this study, we observed ice-out timing on 55 large lakes in 11 lake districts across Alaska from 2007 to 2012 using satellite imagery. Sensor networks in two lake districts validated satellite observations and provided comparison with smaller lakes. Over this 6 yr period, the mean lake ice-out for all lakes was 27 May and ranged from 07 May in Kenai to 06 July in Arctic Coastal Plain lake districts with relatively low inter-annual variability. Approximately 80% of the variation in ice-out timing was explained by the date of 0°C air temperature isotherm and lake area. Shoreline irregularity, watershed area, and river connectivity explained additional variation in some districts. Coherence in ice-out timing within the lakes of each district was consistently strong over this 6 yr period, ranging from r-values of 0.5 to 0.9. Inter-district analysis of coherence also showed synchronous ice-out patterns with the exception of the two arctic coastal districts where ice-out occurs later (June–July) and climatology is sea-ice influenced. These patterns of lake ice phenology provide a spatially extensive baseline describing short-term temporal variability, which will help decipher longer term trends in ice phenology and aid in representing the role of lake ice in land and climate models in northern landscapes.

GRRATS: A New Approach to Inland Altimetry Processing for Major World Rivers

NASA Astrophysics Data System (ADS)

Coss, S. P.

2016-12-01

Here we present work-in-progress results aimed at generating a new radar altimetry dataset GRRATS (Global River Radar Altimetry Time Series) extracted over global ocean-draining rivers wider than 900 m. GRATTS was developed as a component of the NASA MEaSUREs project (PI: Dennis Lettenmaier, UCLA) to generate pre-SWOT data products for decadal or longer global river elevation changes from multi-mission satellite radar altimetry data. The dataset at present includes 909 time series from 39 rivers. A new method of filtering VS (virtual station) height time series is presented where, DEM based heights were used to establish limits for the ice1 retracked Jason2 and Envisat heights at present. While GRRATS is following in the footsteps of several predecessors, it contributes to one of the critical climate data records in generating a validated and comprehensive hydrologic observations in river height. The current data product includes VSs in north and south Americas, Africa and Eurasia, with the most comprehensive set of Jason-2 and Envisat RA time series available for North America and Eurasia. We present a semi-automated procedure to process returns from river locations, identified with Landsat images and updated water mask extent. Consistent methodologies for flagging ice cover are presented. DEM heights used in height filtering were retained and can be used as river height profiles. All non-validated VS have been assigned a letter grade A-D to aid end users in selection of data. Validated VS are accompanied with a suite of fit statistics. Due to the inclusiveness of the dataset, not all VS were able to undergo validation (415 of 909), but those that were demonstrate that confidence in the data product is warranted. Validation was accomplished using records from 45 in situ gauges from 12 rivers. Meta-analysis was performed to compare each gauge with each VS by relative height. Preliminary validation results are as follows. 89.3% of the data have positive Nash Sutcliff Efficiency (NES) values, and the median NSE value is 0.73. The median standard deviation of error (STDE) is .92 m. GRRATS will soon be publicly available in NetCDF format with CF compliant metadata.

2009 Spring floods in North Dakota, western Minnesota, and northeastern South Dakota

USGS Publications Warehouse

Macek-Rowland, Kathleen M.; Gross, Tara A.

2011-01-01

In 2009, record-breaking snowfalls and additional spring moisture caused severe flooding in parts of the Missouri River and Red River of the North (Red River) Basins in North Dakota, Minnesota, and South Dakota. There were 48 peak of record stages and 36 discharges recorded at U.S. Geological Survey streamgages located in both basins between March 20 and May 15, 2009. High water continued to affect many communities up and down the rivers' main stems and tributaries for nearly 2 months. Record snowfall for single-day totals, as well as monthly totals, occurred throughout the Missouri River and Red River of the North Basins. Additional moisture in the spring as well as the timing of warmer temperatures caused record flooding in many places in both basins with many locations reporting two flood crests. Ice jams on the Missouri River, located north and south of Bismarck, N. Dak., caused flooding. Southwest Bismarck was evacuated as rising waters first began inundating homes in low-lying areas along the river and then continued flowing into the city's lower south side. On March 24, 2009, the peak stage of the Missouri River at Bismarck, N. Dak. streamgage was 16.11 feet, which was the highest recorded stage since the completion of Garrison Dam in 1954. South of Bismarck, the Missouri River near Schmidt, N. Dak. streamgage recorded a peak stage of 24.24 feet on March 25, 2009, which surpassed the peak of record of 23.56 feet that occurred on December 9, 1976. While peak stage reached record levels at these streamgages, the discharge through the river at these locations did not reach record levels. The record high stages resulted from ice jams occurring on the Missouri River north and south of the cities of Bismarck and Mandan. At the Red River of the North at Fargo, N. Dak. streamgage, the Red River reached a record stage of 40.84 feet surpassing the previous peak of record stage of 39.72 feet set in 1997. The associated peak streamflow of 29,500 cubic feet per second exceeded the previous peak of record set in 1997 by 1,500 cubic feet per second. For the cities of Fargo, and Moorhead, Minn., and the surrounding area, the stage of the Red River remained above flood stage for nearly 2 months. In addition to high stage and flow on the main-stem Missouri and Red Rivers, peak of record stage and discharge were recorded at many U.S. Geological Survey streamgages in the Missouri River and Red River Basins. Several reservoirs and lakes in the region also experienced record stage elevations from the high flows during the 2009 spring snowmelt floods.

Comparison of modelled runoff with observed proglacial discharge across the western margin of the Greenland ice sheet

NASA Astrophysics Data System (ADS)

Moustafa, S.; Rennermalm, A.; van As, D.; Overeem, I.; Tedesco, M.; Mote, T. L.; Koenig, L.; Smith, L. C.; Hagedorn, B.; Sletten, R. S.; Mikkelsen, A. B.; Hasholt, B.; Hall, D. K.; Fettweis, X.; Pitcher, L. H.; Hubbard, A.

2017-12-01

Greenland ice sheet surface ablation now dominates its total mass loss contributions to sea-level rise. Despite the increasing importance of Greenland's sea-level contribution, a quantitative inter-comparison between modeled and measured melt, runoff and discharge across multiple drainage basins is conspicuously lacking. Here we investigate the accuracy of model discharge estimates from the Modèle Atmosphérique Régionale (MAR v3.5.2) regional climate model by comparison with in situ proglacial river discharge measurements at three West Greenland drainage basins - North River (Thule), Watson River (Kangerlussuaq), and Naujat Kuat River (Nuuk). At each target catchment, we: 1) determine optimal drainage basin delineations; 2) assess primary drivers of melt; 3) evaluate MAR at daily, 5-, 10- and 20-day time scales; and 4) identify potential sources for model-observation discrepancies. Our results reveal that MAR resolves daily discharge variability poorly in the Nuuk and Thule basins (r2 = 0.4-0.5), but does capture variability over 5-, 10-, and 20-day means (r2 > 0.7). Model agreement with river flow data, though, is reduced during periods of peak discharge, particularly for the exceptional melt and discharge events of July 2012. Daily discharge is best captured by MAR across the Watson River basin, whilst there is lower correspondence between modeled and observed discharge at the Thule and Naujat Kuat River basins. We link the main source of model error to an underestimation of cloud cover, overestimation of surface albedo, and apparent warm bias in near-surface air temperatures. For future inter-comparison, we recommend using observations from catchments that have a self-contained and well-defined drainage area and an accurate discharge record over variable years coincident with a reliable automatic weather station record. Our study highlights the importance of improving MAR modeled surface albedo, cloud cover representation, and delay functions to reduce model error and to improve prediction of Greenland's future runoff contribution to global sea level rise.

2. STONE ARCH BRIDGE. TIMBERS ON THE UPSTREAM FACE OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. STONE ARCH BRIDGE. TIMBERS ON THE UPSTREAM FACE OF THE PIER PROTECTED THE STONEWORK FROM DAMAGE FROM ICE FLOWS, BARGES, ETC. - Lockport Historic District, Stone Arch Bridge, Spanning Des Plaines River at Ninth Street, Lockport, Will County, IL

Glacial Meltwater Contirbutions to the Bow River, Alberta, Canada

NASA Astrophysics Data System (ADS)

Bash, E. A.; Marshall, S. J.; White, E. C.

2009-12-01

Assessment of glacial melt is critical for water resource management in areas which rely on glacier-fed rivers for agricultural and municipal uses. Changes in precipitation patterns coupled with current glacial retreat are altering the glacial contribution to river flow in areas such as the Andes of South America and the high ranges of Asia, as well as the Rockies of Western Canada. Alberta’s Bow River has its headwaters in the eastern slopes of the Canadian Rockies and contributes to the Nelson drainage system feeding into Hudson Bay. The Bow River basin contains several population centers, including the City of Calgary, and is heavily taxed for agricultural use. The combined effects of rapid glacial retreat in the Canadian Rockies, higher drought frequency, and increased demand are likely to heighten water stress in Southern Alberta. However, there has been little focus to date on the extent and importance of glacial meltwater in the Bow River. The Bow River contains 74.5 km2 of glacier ice, which amounts to only 0.29% of the basin. While this number is not high compared to some glacierized areas, Hopkinson and Young (1998) report that in dry years, glacier melt can provide up to 50% of late summer flows at a station in the upper reaches of the river system. We extend this work with an assessment of monthly and annual glacial contributions to the Bow River farther downstream in Calgary. Our analysis is based on mass balance, meteorological, and hydrological data that has been collected at the Haig Glacier since 2001. This data is used in conjunction with glacier coverage and hypsometric data for the remainder of the basin to estimate seasonal snow and glacial meltwater contributions to the Bow River from the glacierized fraction of the catchment. The results of this study show the percentage of total flow attributed to glacial melt to be highly variable. Glacier runoff contributes up to an order of magnitude more water to the Bow River per unit area of landscape, relative to the average areal contributions in the basin, accounting for 2-4% of the total flow in an average year, with glacier ice representing about 50% of this total. Future research is examining the impact of ongoing glacier retreat on these contributions and the seasonality of runoff.

Assessing water resources under climate change in high-altitude catchments: a methodology and an application in the Italian Alps

NASA Astrophysics Data System (ADS)

Aili, T.; Soncini, A.; Bianchi, A.; Diolaiuti, G.; D'Agata, C.; Bocchiola, D.

2018-01-01

Assessment of the future water resources in the Italian Alps under climate change is required, but the hydrological cycle of the high-altitude catchments therein is poorly studied and little understood. Hydrological monitoring and modeling in the Alps is difficult, given the lack of first hand, site specific data. Here, we present a method to model the hydrological cycle of poorly monitored high-altitude catchments in the Alps, and to project forward water resources availability under climate change. Our method builds on extensive experience recently and includes (i) gathering data of climate, of cryospheric variables, and of hydrological fluxes sparsely available; (ii) robust physically based glacio-hydrological modeling; and (iii) using glacio-hydrological projections from GCM models. We apply the method in the Mallero River, in the central (Retiche) Alps of Italy. The Mallero river covers 321 km2, with altitude between 310 and 4015 m a.s.l., and it has 27 km2 of ice cover. The glaciers included in the catchment underwent large mass loss recently, thus Mallero is largely paradigmatic of the present situation of Alpine rivers. We set up a spatially explicit glacio-hydrological model, describing the cryospheric evolution and the hydrology of the area during a control run CR, from 1981 to 2007. We then gather climate projections until 2100 from three Global Climate Models of the IPCC AR5 under RCP2.6, RCP4.5, and RCP8.5. We project forward flow statistics, flow components (rainfall, snow melt, ice melt), ice cover, and volume for two reference decades, namely 2045-2054 and 2090-2099. We foresee reduction of the ice bodies from - 62 to - 98% in volume (year 2100 vs year 1981), and subsequent large reduction of ice melt contribution to stream flows (from - 61 to - 88%, 2100 vs CR). Snow melt, now covering 47% of the stream flows yearly, would also be largely reduced (from - 19 to - 56%, 2100 vs CR). The stream flows will decrease on average at 2100 (from + 1 to - 25%, with - 7%), with potential for increased flows during fall, and winter, and large decrease in summer. Our results provide a tool for consistent modeling of the cryospheric, and hydrologic behavior, and can be used for further investigation of the high-altitude catchments in the Alps.

Sea-level responses to sediment transport over the last ice age cycle

NASA Astrophysics Data System (ADS)

Ferrier, K.; Mitrovica, J. X.

2013-12-01

Sea-level changes over the last ice age cycle were instrumental in steering Earth's topographic evolution. These sea-level variations were driven by changes in surface mass loads, including not only ice and ocean mass variations but also the transfer of rock from eroding mountains to sedimentary deposits. Here we use an extended numerical model of ice age sea level (Dalca et al., 2013) to explore how sediment erosion and deposition affected global sea-level variations over the last ice age cycle. The model takes histories of ice and sediment loads as inputs, and it computes gravitationally self-consistent sea level responses by accounting for the deformational, gravitational, and rotational perturbations in the Earth's viscoelastic form. In these model simulations, we use published estimates of erosion rates, sedimentation rates, and ice sheet variations to constrain sediment and ice loading since the Last Interglacial. We explore sea-level responses to several erosional and depositional scenarios, and in each we quantify the relative contributions of crustal deformation and gravitational perturbation to the computed sea-level change. We also present a case study to illustrate the effects that sediment transfer can have on sea level at the regional scale. In particular, we focus on the region surrounding the Indus River, where fluvial sediment fluxes are among the highest on Earth. Preliminary model results suggest that sediment fluxes from Asia to the ocean are large enough to produce a significant response in sea level along the northeastern coast of the Arabian Sea. Moreover, they suggest that modeled sea-level histories are sensitive to the timing and spatial distribution of sediment erosion and deposition. For instance, sediment deposition along the continental shelf - which may have been the primary site of Indus River sediment deposition during the Holocene - produces a different sea-level response than sediment deposition on the deep-sea Indus Fan, where most of the Indus sediment may have been deposited during the glacial period preceding the Holocene. These simulations highlight the role that massive continent-to-ocean sediment fluxes can play in driving sea-level patterns over thousands of years. References: Dalca A.V., Ferrier K.L., Mitrovica J.X., Perron J.T., Milne G.A., Creveling J.R., 2013. On postglacial sea level - III: Incorporating sediment redistribution. Geophys. J. Int., doi: 10.1093/gji/ggt089.

The demographic response of bank-dwelling beavers to flow regulation: A comparison on the Green and Yampa rivers

USGS Publications Warehouse

Breck, S.W.; Wilson, K.R.; Andersen, D.C.

2001-01-01

We assessed the effects of flow regulation on the demography of beavers (Castor canadensis) by comparing the density, home-range size, and body size of bank-dwelling beavers on two sixth-order alluvial river systems, the flow-regulated Green River and the free-flowing Yampa River, from 1997 to 2000. Flow regulation on the Green River has altered fluvial geomorphic processes, influencing the availability of willow and cottonwood, which, in turn, has influenced the demography of beavers. Beaver density was higher on the Green River (0.5–0.6 colonies per kilometre of river) than on the Yampa River (0.35 colonies per kilometre of river). Adult and subadult beavers on the Green River were in better condition, as indicated by larger body mass and tail size. There was no detectable difference in home-range size, though there were areas on the Yampa River that no beavers used. We attribute the improved habitat quality on the Green River to a greater availability of willow. We suggest that the sandy flats and sandbars that form during base flows and the ice cover that forms over winter on the Yampa River increase the energy expended by the beavers to obtain food and increase predation risk and thus lowers the availability of woody forage.

Monitoring Supraglacial Streams over Three Months in Southwest Greenland

NASA Astrophysics Data System (ADS)

Muthyala, R.; Rennermalm, A.; Leidman, S. Z.; Cooper, M. G.; Cooley, S. W.; Smith, L. C.; van As, D.

2017-12-01

Supraglacial river networks are the most efficient conduits for evacuation of meltwater runoff produced on Greenland ice sheet. These rivers are prominent features on the ablation zone of southwest Greenland. However, little is known about the transport of meltwater through supraglacial stream network and most of the in-situ observations only capture a few days of streamflow. Here we report three months of observations of water level and discharge collected during summer of 2016, in two small supraglacial streams near the ice sheet margin in southwest Greenland. We also compare streamflow observations with meteorological data from a nearby automatic weather station. The two sites are very different, with the lower basin relatively steep, smooth and dark while the upper basin has rugged terrain and deeply incised stream channels. These catchment characteristics propagate to different relationships with meteorological parameters. For example, upper basin stream water levels show a strong covariance with surface temperature while the lower basin water levels do not. We also find differences in temporal variation of supraglacial stream water level, with the upper basin having two distinct peaks, in mid-June and mid-July, while the lower basin shows gradual decrease from June to August. Long-term supraglacial stream observations such as these will ultimately help assess how well surface mass balance models can simulate ice sheet runoff.

Impact of the German Harz Mountain Weichselian ice-shield and valley glacier development onto Palaeolithic and megafauna disappearances

NASA Astrophysics Data System (ADS)

Diedrich, C.

2013-12-01

Three Pleistocene stages are recorded by 3D Google-Earth geomorphology, cave sediments, river terraces, megafauna, archaeological sites of the Harz Mountain Range and its forelands of northern Germany (central Europe, peak 1141 a.s.l.). Late Pleistocene glaciation stages are modeled preliminary in valley elevations between 407 and 760 a.s.l., starting all southeast below the Brocken Ice Field (above 750 a.s.l.). The 14-11 km long Oder and Bode Valley glaciers left typical moraines, kames, or dead ice depressions, such as fluvial cave relic sediments. The Bode River glacier passed during the LGM the Rübeland Caves, where it deposited reworked kames/lateral moraines in the Baumann's Cave, which floods mixed a Neanderthal camp, leopard lair and cave bear den area. 60 km downstream, fluvial to aeolian deposits were trapped in the gypsum karst doline Westeregeln (Neanderthal camp/hyena den). Late Aurignacians replaced in the region Neanderthals, but a gap of Late Palaeolithic (Gravettian-Magdalenian - 26,000-16,000 BP) settlement, and latest starting speleothem genesis (around 24,260 ± 568 BP) correlate to the LGM, when an "arctic reindeer fauna" with alpine elements (ibex, chamois) accumulated in bone assemblages of a wolverine, polar fox, mustelid, such as European eagle owl dens, which allow landscape reconstructions.

Meltwater export of prokaryotic cells from the Greenland ice sheet.

PubMed

Cameron, Karen A; Stibal, Marek; Hawkings, Jon R; Mikkelsen, Andreas B; Telling, Jon; Kohler, Tyler J; Gözdereliler, Erkin; Zarsky, Jakub D; Wadham, Jemma L; Jacobsen, Carsten S

2017-02-01

Microorganisms are flushed from the Greenland Ice Sheet (GrIS) where they may contribute towards the nutrient cycling and community compositions of downstream ecosystems. We investigate meltwater microbial assemblages as they exit the GrIS from a large outlet glacier, and as they enter a downstream river delta during the record melt year of 2012. Prokaryotic abundance, flux and community composition was studied, and factors affecting community structures were statistically considered. The mean concentration of cells exiting the ice sheet was 8.30 × 10 4 cells mL -1 and we estimate that ∼1.02 × 10 21 cells were transported to the downstream fjord in 2012, equivalent to 30.95 Mg of carbon. Prokaryotic microbial assemblages were dominated by Proteobacteria, Bacteroidetes, and Actinobacteria. Cell concentrations and community compositions were stable throughout the sample period, and were statistically similar at both sample sites. Based on our observations, we argue that the subglacial environment is the primary source of the river-transported microbiota, and that cell export from the GrIS is dependent on discharge. We hypothesise that the release of subglacial microbiota to downstream ecosystems will increase as freshwater flux from the GrIS rises in a warming world. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

The Multitrophic Effects of Climate Change and Glacier Retreat in Mountain Rivers

PubMed Central

2017-01-01

Abstract Climate change is driving the thinning and retreat of many glaciers globally. Reductions of ice-melt inputs to mountain rivers are changing their physicochemical characteristics and, in turn, aquatic communities. Glacier-fed rivers can serve as model systems for investigations of climate-change effects on ecosystems because of their strong atmospheric–cryospheric links, high biodiversity of multiple taxonomic groups, and significant conservation interest concerning endemic species. From a synthesis of existing knowledge, we develop a new conceptual understanding of how reducing glacier cover affects organisms spanning multiple trophic groups. Although the response of macroinvertebrates to glacier retreat has been well described, we show that there remains a relative paucity of information for biofilm, microinvertebrate, and vertebrate taxa. Enhanced understanding of whole river food webs will improve the prediction of river-ecosystem responses to deglaciation while offering the potential to identify and protect a wider range of sensitive and threatened species. PMID:29599537

The Multitrophic Effects of Climate Change and Glacier Retreat in Mountain Rivers.

PubMed

Fell, Sarah C; Carrivick, Jonathan L; Brown, Lee E

2017-10-01

Climate change is driving the thinning and retreat of many glaciers globally. Reductions of ice-melt inputs to mountain rivers are changing their physicochemical characteristics and, in turn, aquatic communities. Glacier-fed rivers can serve as model systems for investigations of climate-change effects on ecosystems because of their strong atmospheric-cryospheric links, high biodiversity of multiple taxonomic groups, and significant conservation interest concerning endemic species. From a synthesis of existing knowledge, we develop a new conceptual understanding of how reducing glacier cover affects organisms spanning multiple trophic groups. Although the response of macroinvertebrates to glacier retreat has been well described, we show that there remains a relative paucity of information for biofilm, microinvertebrate, and vertebrate taxa. Enhanced understanding of whole river food webs will improve the prediction of river-ecosystem responses to deglaciation while offering the potential to identify and protect a wider range of sensitive and threatened species.

Possible precipitation of ice at low latitudes of Mars during periods of high obliquity

USGS Publications Warehouse

Jakosky, B.M.; Carr, M.H.

1985-01-01

Most of the old cratered highlands of Mars are dissected by branching river valleys that appear to have been cut by running water1,2 yet liquid water is unstable everywhere on the martian surface. In the equatorial region, where most of the valleys are observed, even ice is unstable3,4. It has been suggested, therefore, that Mars had an early denser atmosphere with sufficient greenhouse warming to allow the existence of liquid water 5. Here, we suggest instead that during periods of very high obliquities, ice could accumulate at low latitudes as a result of sustained sublimation of ice from the poles and transport of the water vapour equatorwards. At low latitudes, the water vapour would saturate the atmosphere and condense onto the surface where it would accumulate until lower obliquities prevailed. The mechanism is efficient only at the very high obliquities that occurred before formation of Tharsis very early in the planet's history, but limited equatorial ice accumulation could also have occurred at the highest obliquities during the rest of the planet's history. Partial melting of the ice could have provided runoff to form the channels or replenish the groundwater system. ?? 1985 Nature Publishing Group.

Possible precipitation of ice at low latitudes of Mars during periods of high obliquity

NASA Technical Reports Server (NTRS)

Jakosky, B. M.; Carr, M. H.

1985-01-01

Most of the old cratered highlands of Mars are dissected by branching river valleys that appear to have been cut by running water, yet liquid water is unstable everywhere on the Martian surface. In the equatorial region, where most of the valleys are observed, even ice is unstable. It has been suggested, therefore, that Mars had an early denser atmosphere with sufficient greenhouse warming to allow the existence of liquid water. Here, it is suggested instead that during periods of very high obliquities, ice could accumulate at low latitudes as a result of sustained sublimation of ice from the poles and transport of the water vapor equatorwards. At low latitudes, the water vapor would saturate the atmosphere and condense onto the surface, where it would accumulate until lower obliquities prevailed. The mechanism is efficient only at the very high obliquities that occurred before formation of Tharsis very early in the planet's history, but limited equatorial ice accumulation could also have occurred at the highest obliquities during the rest of the planet's history. Partial melting of the ice could have provided runoff to form the channels or replenish the groundwater system.

Continental-scale transport of sediments by the Baltic Ice Stream elucidated by coupled grain size and Nd provenance analyses

NASA Astrophysics Data System (ADS)

Boswell, Steven M.; Toucanne, Samuel; Creyts, Timothy T.; Hemming, Sidney R.

2018-05-01

We introduce a methodology for determining the transport distance of subglacially comminuted and entrained sediments. We pilot this method on sediments from the terminal margin of the Baltic Ice Stream, the largest ice stream of the Fennoscandian Ice Sheet during the Last Glacial Maximum. A strong correlation (R2 = 0.83) between the εNd and latitudes of circum-Baltic river sediments enables us to use εNd as a calibrated measure of distance. The proportion of subglacially transported sediments in a sample is estimated from grain size ratios in the silt fraction (<63 μm). Coupled εNd and grain size analyses reveal a common erosion source for the Baltic Ice Stream sediments located near the Åland sill, more than 850 km upstream from the terminal moraines. This result is in agreement with both numerical modeling and geomorphological investigations of Fennoscandinavian erosion, and is consistent with rapid ice flow into the Baltic basins prior to the Last Glacial Maximum. The methodology introduced here could be used to infer the distances of glacigenic sediment transport from Late Pleistocene and earlier glaciations.

Implications for an Enhanced Biological Pump in the Sea-Ice Reduction Region of the Western Arctic Ocean

NASA Astrophysics Data System (ADS)

Nishino, S.; Shimada, K.; Itoh, M.; Yamamoto-Kawai, M.; Chiba, S.

2009-12-01

Since the late 1990s, catastrophic sea-ice reduction during summer has been observed in the western Arctic Ocean. Regions of decreasing sea ice might be associated with increased biological production compared to ice-covered ocean areas due to light intensification in the water column. The R/V Mirai field experiments in summer 2004 revealed that the algal biomass (chlorophyll a) in the open water region of the western Canada Basin increased from that observed in summer 1994, when the sea ice covered that area. Under the euphotic zone of the increased algal biomass area, evidence of diatom detritus decomposition was found, while such evidence was not observed in 1994, suggesting an enhancement of biological pump (see figure). The increase of algal biomass was not found throughout the sea-ice reduction region; rather, it was observed western Canada Basin where nutrients are effectively supplied from shelf regions. Further west from the Canada Basin, Russian river water with relatively high nutrients may play an important role in the biogeochemical cycles. Monthly sea-ice concentrations (white = 100%, black = 0%) in September of (a) 1994 and (b) 2004 (National Ice Center), and (c) vertical profiles of silicate obtained from the field experiments of Arctic Ocean Section 94 in 1994 (○) and Mirai04 in 2004 (■). The positions where the profiles were obtained are depicted by dots in (a) and (b), respectively.

McNary Dam, Ice Harbor Dam, and Lower Monumental Dam Smolt Monitoring Program; 1996 Annual Report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hillson, Todd; Lind, Sharon; Price, William

1997-07-01

The Washington Department of Fish & Wildlife (WDFW) assumed responsibility for the Smolt Monitoring Program at McNary Dam on the Columbia River in 1990 and at the new juvenile collection facility at Lower Monumental Dam on the Snake River in 1993. In 1996, Smolt Monitoring Program activities also began at the new juvenile collection facility located at Ice Harbor Dam. This report summarizes the 1996 Smolt Monitoring work at all three sites. The work at Ice Harbor consisted of Gas Bubble Trauma (GBT) monitoring only. In general, the 1996 passage season at both the McNary and Lower Monumental sites canmore » be characterized by reduced passage of juveniles through the collection systems due to elevated river flows and spill, and low (<1%) overall facility mortality rates most likely resulting from cooler water temperatures. In accordance with the National Marine Fisheries Service recommendations (NMFS, 1995) all spring migrants were bypassed at McNary Dam in 1996. Mechanical problems within the McNary collection system resulted in collection and sampling activities being delayed until April 18 at this site, while sampling and collection began on the scheduled starting date of April 1 at Lower Monumental Dam. Monitoring operations were conducted through December 14 at McNary Dam and through October 28 at Lower Monumental Dam. An ongoing transportation evaluation summer migrant marking program was conducted at McNary Dam in 1996 by the NMFS. This necessitated the sampling of 394,211 additional fish beyond the recommended sampling guidelines. All total, 509,237 and 31,219 juvenile salmonids were anesthetized and individually counted, examined for scale loss, injuries, and brands by WDFW Smolt Monitoring personnel in 1996 at McNary Dam and Lower Monumental Dam, respectively.« less

Deciphering the impact of change on the driftwood cycle: contribution to the study of human use of wood in the Arctic

NASA Astrophysics Data System (ADS)

Alix, Claire

2005-07-01

Driftwood that originates in the Siberian and North American boreal forest is the major source of wood to people in the treeless Arctic. It archives various kinds of data about climate, river flow, ocean and ice circulation, and other critical environmental and cultural characteristics in the north. Unlike wood in most other regions, it is often well preserved in arctic archaeological sites. The existence and renewal of driftwood are closely linked to specific climatic and ecological conditions that have changed through time (e.g., floods, river banks, storms, prevailing currents and winds, sea-ice circulation, etc.). These conditions differently affect the fall, circulation and delivery of driftwood to the coast, resulting in changes in abundance, distribution and intrinsic properties of the wood. Based on a review of existing literature supplemented by new data from Alaska, this paper details factors underlying the "dynamic of driftwood production" in terms of driftwood abundance and quality, and indigenous people's use of the resource. Oral history interviews in coastal and river communities of Alaska recorded knowledge on driftwood use and ecology. Driftwood samples were collected from accumulations along the northwest coast of Alaska and the south of the Chukotka Peninsula. Results show that the timing of treefall and river transport are crucial to the subsequent ocean circulation and may determine the size and quality of the wood. Ultimately, it conditions what coastal people could build or manufacture.

Interactions of frazil and anchor ice with sedimentary particles in a flume

USGS Publications Warehouse

Kempema, E.W.; Reimnitz, E.; Clayton, J.R.; Payne, J.R.

1993-01-01

Frazil and anchor ice forming in turbulent, supercooled water have been studied extensively because of problems posed to man-made hydraulic structures. In spite of many incidental observations of interactions of these ice forms with sediment, their geologic effects remain unknown. The present flume study was designed to learn about the effects of salinity, current speed, and sediment type on sediment dynamics in supercooled water. In fresh-water, frazil ice formed flocs as large as 8 cm in diameter that tended to roll along a sandy bottom and collect material from the bed. The heavy flocs often came to rest in the shelter of ripples, forming anchor ice that subsequently was buried by migrating ripples. Burial compressed porous anchor ice into ice-bonded, sediment-rich masses. This process disrupts normal ripple cross-bedding and may produce unique sedimentary structures. Salt-water flocs were smaller, incorporated less bed load, and formed less anchor ice than their fresh-water counterparts. In four experiments, frazil carried a high sediment load only for a short period in supercooled salt water, but released it with slight warming. This suggests that salt-water frazil is either sticky or traps particles only while surrounded by supercooled water (0.05 to 0.1 ??C supercooling), a short-lived phase in simple, small tanks. Salt water anchor ice formed readily on blocks of ice-bonded sediment, which may be common in nature. The theoretical maximum sediment load in neutrally-buoyant ice/sediment mixture is 122 g/l, never reported in nature so far. The maximum sediment load measured in this laboratory study was 88 g/l. Such high theoretical and measured sediment concentrations suggest that frazil and anchor ice are important sediment transport agents in rivers and oceans. ?? 1993.

Deglacial climate modulated by the storage and release of Arctic sea ice

NASA Astrophysics Data System (ADS)

Condron, A.; Coletti, A. J.; Bradley, R. S.

2017-12-01

Periods of abrupt climate cooling during the last deglaciation (20 - 8 kyr ago) are often attributed to glacial outburst floods slowing the Atlantic meridional overturning circulation (AMOC). Here, we present results from a series of climate model simulations showing that the episodic break-up and mobilization of thick, perennial, Arctic sea ice during this time would have released considerable volumes of freshwater directly to the Nordic Seas, where processes regulating large-scale climate occur. Massive sea ice export events to the North Atlantic are generated whenever the transport of sea ice is enhanced, either by changes in atmospheric circulation, rising sea level submerging the Bering land bridge, or glacial outburst floods draining into the Arctic Ocean from the Mackenzie River. We find that the volumes of freshwater released to the Nordic Seas are similar to, or larger than, those estimated to have come from terrestrial outburst floods, including the discharge at the onset of the Younger Dryas. Our results provide the first evidence that the storage and release of Arctic sea ice helped drive deglacial climate change by modulating the strength of the AMOC.

Arctic Sea Ice Structure and Texture over Four Decades Using Landsat Archive Data

NASA Astrophysics Data System (ADS)

Doulgeris, A. P.; Scambos, T.; Tiampo, K. F.

2017-12-01

Arctic sea ice cover is a sensitive indicator of Arctic climate change, and has shown dramatic changes in recent decades, having thinned by 70% ( 3.5 m to 1.2 m between 1980 and 2015). Age distribution of the ice has changed in a similar fashion, with over 90% of the ice older than 5 winters now lost relative to 1985. To date, most of the data have been based on the continuous passive microwave record that began in 1978, which has 25 km grid resolution, or on SAR imagery with somewhat less frequent, less continuous observations. Landsat image data exist for the Arctic sea ice region north of Alaska and the MacKenzie River Delta area in Canada, the Canadian Archipelago, and Baffin Bay, extending back over 40 years. Resolution of the earliest Landsat MSS data is 56-70 m per pixel, and after 1984 many additional images at 30 m resolution are available. This 40+ year time period is used to investigate long-term changes in sea ice properties, such as comparing image-based snapshots with the trend in seasonal extents today, as well as more novel properties like sea ice roughness, lead structure and texture. The proposed study will initially investigate Landsat image analysis techniques to extract quantitative measures of ice roughness, lead fraction and perhaps morphological measures like lead linearity (which potentially indicate strength and compression history within the ice), and to explore these measures over the 40+ year time frame.

77 FR 12835 - Environmental Impacts Statements; Notice of Availability

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-02

... EIS, BR, WA, PROGRAMMATIC--Yakima River Basin Integrated Water Resource Management Plan, To Meet the..., Buck Island Reef National Monument General Management Plan, Implementation, St. Croix, Virgin Islands... Management Plan, Implementation, Ice Age National Scenic Trail, Dane County, WI, Comment Period Ends: 04/30...

Impacts of climate change on the food-energy-water nexus in the upper Yellow River Basin: An integrated hydro-economic modeling approach

NASA Astrophysics Data System (ADS)

Si, Y.; Cai, X.

2017-12-01

The large-scale reservoir system built on the upper Yellow River serves multiple purposes. The generated hydropower supplies over 60% of the entire electricity for the regional power grid while the irrigated crop production feeds almost one-third of the total population throughout the whole river basin. Moreover, the reservoir system also bears the responsibility for controlling ice flood, which occurs during the non-flood season due to winter ice freezing followed by spring thawing process, and could be even more disastrous than the summer flood. The contradiction of water allocation to satisfy multi-sector demands while mitigating ice flood risk has been longstanding. However, few researchers endeavor to employ the nexus thinking to addressing the complexities involved in all the interlinked purposes. In this study, we develop an integrated hydro-economic model that can be used to explore both the tradeoffs and synergies between the multiple purposes, based on which the water infrastructures (e.g., reservoir, diversion canal, pumping well) can be coordinated for maximizing the co-benefits of multiple sectors. The model is based on a node-link schematic of multiple operations including hydropower generation, irrigation scheduling, and the conjunctive use of surface and ground water resources. In particular, the model depicts some details regarding reservoir operation rules during the ice season using two indicators, i.e., flow control period and flow control level. The rules are obtained from historical records using data mining techniques under different climate conditions, and they are added to the model as part of the system constraints. Future reservoir inflow series are generated by a hydrological model with future climate scenarios projected by General Circulation Model (GCM). By analyzing the model results under the various climate scenarios, the future possible shifting trajectory of the food-energy-water system characteristics will be derived compared to the baseline scenario (i.e., the status-quo condition). Thus the model and the results are expected to be useful for enlightening economically efficient water allocation policy coping with climate change.

Progress on observation of cryospheric components and climate-related studies in China

NASA Astrophysics Data System (ADS)

Xiao, Cunde; Qin, Dahe; Yao, Tandong; Ding, Yongjian; Liu, Shiyin; Zhao, Lin; Liu, Yujie

2008-03-01

Systematic studies on the cryosphere in China started in the late 1950s. Significant achievements have been made by continuous investigation of glacier inventories, frozen ground observations, paleo-climate analyses of ice cores, process studies and the modeling of cryopsheric/atmospheric interactions. The general facts and understanding of these changes include: (1) Solid precipitation, including the number of days with frost and hail storms, shows a decreasing tendency over the past half century. (2) In most areas glaciers are retreating or have completely vanished (>80%), some glaciers are still advancing (5%-20% depending upon time period). The annual glacial melt water has been increasing since the 1980s. This increased supply of melt water to river runoff in Northwest China is about a 10%-13%. (3) The long-term variability of snow cover in western China is characterized by a large inter-annual variation superimposed on a small increasing trend. Snow cover variability in the Qinghai-Xizang Plateau (QXP) is influenced by the Indian monsoon, and conversely impacts monsoon onset and strength and eventually the drought and flood events in middle-low reaches of Yangtze River. (4) Frozen ground, including permafrost, is decaying both in QXP and in Northeast China. The most significant changes occurred in the regions with thickest seasonal frozen ground (SFG), i.e., inland QXP, then northeastern and northwestern QXP. The cold season air temperature is the main factor controlling SFG change. The increase of ground surface temperatures is more significant than air temperature. (5) The sea ice coverage over the Bohai Sea and Yellow Sea has deceased since the 1980s. (6) River ice duration and ice thickness is also decreasing in northern China. In 2001, the Chinese National Committee of World Climate Research Program/Climate and Cyosphere (WCRP/CliC) (CNC-CliC) was organized to strengthen research on climate and cryosphere in China. Future monitoring of the cryosphere in China will be enhanced both in spatial coverage and through the use of new techniques. Interactions between atmosphere/cryosphere/ hydrosphere/land-surface will be assessed to improve our understanding of the mechanisms of cryospheric change.

Do Atmospheric Circulation Patterns Explain Variability and Trends in The Seasonality of Oulu-Hailuoto Ice Road in Northern Finland?

NASA Astrophysics Data System (ADS)

Ahmadi, B.; Kiani, S.; Irannezhad, M.; Ronkanen, A. K.; Kløve, B.; Moradkhani, H.

2016-12-01

In cold climate regions, ice roads are engineered as temporary winter transportation routes on the frozen seas, lakes and rivers. The ice road season parameters (start, end and length) are principally dependent on the thickness of ice, which is naturally controlled by temperature in terms of freezing (FDDs) and thawing (TDDs) degree-days. It has been shown that the variations in FDDs and TDDs are influenced by large-scale atmospheric circulation patterns (ACPs). Therefore, this study aims at understanding the role of ACPs in variability and trends in the seasonality of Oulu-Hailuoto ice road in northern Finland during 1974-2009. The Mann-Kendall nonparametric trend test determined significant shortening in the length of ice road season over the study period of 1974-2009, which can be attributed to later start and earlier end days. In the study area, the maximum ice thickness of the Baltic Sea also showed significant declines over time. Such sea ice thinning can be associated with the wintertime temperature warming manifested by the decreasing trend found in the cumulative FDD during October-January in the water year (September-August). The increased cumulative TDD during February-April also reflects warmer climate in spring, which has resulted in the earlier end day of the ice road season. Measuring the Spearman's rank correlation identified the Arctic Oscillation as the most significant ACP influencing variations in the cumulative FDD, and accordingly in the ice thickness and the start day. However, the cumulative TDD during February-April shows significant positive correlation with the East Atlantic (EA) pattern, which appears to control the end day of the Oulu-Hailuoto ice road season.

Marine Corps Amphibious Combat Vehicle (ACV) and Marine Personnel Carrier (MPC): Background and Issues for Congress

DTIC Science & Technology

2017-03-08

amphibious like an AAV, EFV, or the ACV but instead would be required to have a swim capability for inland waterways such as rivers, lakes , and other...operations. On June 14, 2013, Marine leadership put the MPC program “on ice ” due to budgetary pressures but suggested the program might be resurrected some...EFV, or the ACV but instead would be required to have a swim 1 capability for inland waterways such as rivers, lakes , and other water obstacles

Detroit, MI, Toledo, OH and Lake Erie

NASA Image and Video Library

1973-06-22

SL2-05-390 (22 June 1973) --- Greater Detroit (42.0N, 82.5W) is located at the southeastern border of Michigan on the Detroit River across from Windsor, Ontario, Canada and Lake Huron to the north. The river connecting Lake Erie is a channel left over from the Ice Age Glaciers. The land use pattern in this scene is typical of this part of the upper Midwest. The once extensive forests have been cleared for farmland and pasture, but narrow rows of trees still line farm boundaries. Photo credit: NASA

A short circuit in thermohaline circulation: A cause for northern hemisphere glaciation?

PubMed

Driscoll; Haug

1998-10-16

The cause of Northern Hemisphere glaciation about 3 million years ago remains uncertain. Closing the Panamanian Isthmus increased thermohaline circulation and enhanced moisture supply to high latitudes, but the accompanying heat would have inhibited ice growth. One possible solution is that enhanced moisture transported to Eurasia also enhanced freshwater delivery to the Arctic via Siberian rivers. Freshwater input to the Arctic would facilitate sea ice formation, increase the albedo, and isolate the high heat capacity of the ocean from the atmosphere. It would also act as a negative feedback on the efficiency of the "conveyor belt" heat pump.

greenland_summer_campaign

NASA Image and Video Library

2015-08-28

Laurence Smith, chair of geography at University of California, Los Angeles, deploys an autonomous drift boat equipped with several sensors in a meltwater river on the surface of the Greenland ice sheet on July 19, 2015. “Surface melting in Greenland has increased recently, and we lacked a rigorous estimate of the water volumes being produced and their transport,” said Tom Wagner, the cryosphere program scientist at NASA Headquarters in Washington. “NASA funds fieldwork like Smith’s because it helps us to interpret satellite data, and to extrapolate measurements from the local field sites to the larger ice sheet." Credit: NASA/Goddard/Jefferson Beck

Final report for Verglimit at hole-in-the-wall slide section : experimental feature evaluation.

DOT National Transportation Integrated Search

1989-06-01

In 1983, experimental Verglimit overlays were placed on two Oregon bridges known to have icing problems. The performance of the test overlays, constructed on the Salmon River Bridge in Clackamas County and the Quartz Creek Bridge in Clatsop County, w...

Enzymatic Regulation of Organic Matter Metabolism in Siberia's Kolyma River Watershed

NASA Astrophysics Data System (ADS)

Mann, P. J.; Sobczak, W. V.; Vonk, J. E.; Davydova, A.; Schade, J. D.; Bulygina, E. B.; Davydov, S.; Zimov, N.; Holmes, R. M.

2011-12-01

Arctic soils contain vast amounts of ancient organic carbon locked up in permafrost. This organic matter can be unlocked via permafrost thaw and bacterial processing. Microbial communities release enzymes into the environment (ectoenzymes) as a means of degrading organic matter and to acquire carbon, nitrogen and phosphorus for assimilation. Limited ectoenzyme production, or unfavourable in-situ conditions (e.g. temperature, oxygen) can limit degradation of permafrost on land. Environmental conditions may become more favourable for bacterial degradation as carbon compounds are released from permafrost into Arctic streams and rivers. We measured the potential activities of a suite of ectoenzymes within surface waters collected from a range of streams and rivers throughout the Kolyma River basin, Siberia. Ectoenzyme activities were additionally measured in Kolyma river waters collected at three distinct periods of the hydrograph (under-ice, freshet and summer conditions). In total, seven enzymes were studied allowing bacterial requirements for a wide range of compounds including lignin, carbohydrates, proteins and cellulose to be assessed. To investigate the lability of the carbon pool within these waters, we measured the biological oxygen demand over 5 days (BOD). Significant correlations were observed between phenol oxidase activity and BOD across all of the study sites, suggesting the rate of phenolic degradation may be a controlling factor in organic carbon metabolism. The activity rate in ectoenzymes that catalyze phosphate, lignin and carbon substrates varied significantly within the Kolyma river over the hydrograph, indicating that seasonal changes in organic matter composition may also shift the limiting resource for bacterial degradation. High activity rates in ectoenzymes that catalyze lignin, chitin, cellulose and proteins were measured in waters draining permafrost ice complexes. These results suggest that organic carbon is continually processed throughout the stream network, and that its ultimate fate is linked to organic matter composition. We demonstrate that organic carbon derived from ancient permafrost thaw may be highly labile to bacterial communities within Arctic aquatic ecosystems.

Geology and quaternary environments of the first preglacial palaeolithic sites found in Alberta, Canada

NASA Astrophysics Data System (ADS)

Chlachula, Jiří

A pebble-tool industry, including two chronologically different stone artifact assemblages reminiscent of the Eurasian Palaeolithic, has been recorded in Late Pleistocene sections at two locations in the Bow River valley, southwestern Alberta. Authenticity and provenance of the deeply buried archaeological record is evidenced by culture-diagnostic percussion-flaked artifacts incorporated in preglacial fluvial gravels and overlying glacial diamictons and by identical textural patterns on stone tools found in and eroded from the exposures. Geological context suggests a fluctuating braided river setting during the earlier occupation. Discarded ( lower series) quartzite and hard carbonate rock artifacts, subglacially entrained into the Cordilleran Bow Valley till, document distortion of the earlier site (Silver Springs) by a valley glacier emerging from the Rocky Mountain ice-lobe. Following the valley deglaciation, a later occupation episode is manifested by a formally analogous flaked lithic assemblage excavated in situ on top of the till at a nearby site (Varsity Estates). This more recent occupation surface was subsequently buried under 24 m of glaciolacustrine sediments after submergence of the river valley by a proglacial lake (Glacial Lake Calgary) dammed by the Laurentide ice advance into the eastern Calgary area, implying a minimum early Late Wisconsinan age (ca. >21,000 BP) for the lithic industry. The presence of the later ( upper series) artifact assemblage and the associated palynological data do not support the view that envisages an extremely cold, inhospitable glacial environment on the eastern slopes of the Canadian Rocky Mountains throughout the Late Wisconsinan. Their stratigraphic position also indicates temporal asynchroneity between Cordilleran and Laurentide ice during the last glacial maximum in the Bow River valley, the area of presumed coalescence of the two ice-masses. Although a more rapid response of the western mountain glacier to climatic change is evident, the apparent absence of pedogenic alteration of the till surface and the fresh appearance of the excavated stone artifacts suggest that a short time span separated the two glacial events. The archaeological record provides evidence of an earlier Palaeo-American peopling of western interior Canada long before the emergence of the Final Pleistocene Palaeoindian cultures, characterized by elaborate bifacial stone projectile-point flaking technologies traditionally regarded as the earliest cultural manifestations in North America. Silver Springs is the first early site on the continent found below glacial deposits. Realization that other American Palaeolithic sites, potentially of considerable antiquity, should be recognized in similar geological settings, and introduction of adequate geoarchaeological site-survey techniques, have crucial relevance for elucidation of the earliest New World prehistory.

Recent Changes in Arctic Glaciers, Ice Caps, and the Greenland Ice Sheet: Cold Facts About Warm Ice

NASA Astrophysics Data System (ADS)

Abdalati, W.

2005-12-01

One of the major manifestations of Arctic change can be observed in the state of balance of Arctic glaciers and ice caps and the Greenland ice sheet. These ice masses are estimated to contain nearly 3 million cubic kilometers of ice, which is more than six times greater than all the water stored in the Earth's lakes, rivers, and snow combined and is the equivalent of over 7 meters of sea level. Most of these ice masses have been shrinking in recent in years, but their mass balance is highly variable on a wide range of spatial and temporal scales. On the Greenland ice sheet most of the coastal regions have thinned substantially as melt has increased and some of its outlet glaciers have accelerated. Near the equilibrium line in West Greenland, we have seen evidence of summer acceleration that is linked to surface meltwater production, suggesting a relatively rapid response mechanism of the ice sheet change to a warming climate. At the same time, however, the vast interior regions of the Greenland ice sheet have shown little change or slight growth, as accumulation in these areas may have increased. Throughout much of the rest of the Arctic, many glaciers and ice caps have been shrinking in the past few decades, and in Canada and Alaska, the rate of ice loss seems to have accelerated during the late 1990s. These recent observations offer only a snapshot in time of the long-term behavior, but they are providing crucial information about the current state of ice mass balance and the mechanisms that control it in one of the most climatically sensitive regions on Earth. As we continue to learn more through a combination of remote sensing observations, in situ measurements and improved modeling capabilities, it is important that we coordinate and integrate these approaches effectively in order to predict future changes and their impact on sea level, freshwater discharge, and ocean circulation.

Time-series measurements of methane (CH4) distribution during open water and ice-cover in lakes throughout the Mackenzie River Delta (Canada)

NASA Astrophysics Data System (ADS)

McIntosh, H.; Lapham, L.; Orcutt, B.; Wheat, C. G.; Lesack, L.; Bergstresser, M.; Dallimore, S. R.; MacLeod, R.; Cote, M.

2016-12-01

Arctic lakes are known to emit large amounts of methane to the atmosphere and their importance to the global methane (CH4) cycle has been recognized. It is well known CH4 builds up in Arctic lakes during ice-cover, but the amount of and when the CH4 is released to the atmosphere is not well known. Our preliminary results suggest the largest flux of CH4 from lakes to the atmosphere occurs slightly before complete ice-out; while others have shown the largest flux occurs when lakes overturn in the spring. During ice-out, CH4 can also be oxidized by methane oxidizing bacteria before it can efflux to the atmosphere from the surface water. In order to elucidate the processes contributing to Arctic lake CH4 emissions, continuous, long-term and large scale spatial sampling is required; however it is difficult to achieve in these remote locations. We address this problem using two sampling techniques. 1) We deployed osmotically powered pumps (OsmoSamplers), which were able to autonomously and continuously collect lake bottom water over the course of a year from multiple lakes in the Mackenzie River Delta. OsmoSamplers were placed in four lakes in the mid Delta near Inuvik, Northwest Territories, Canada, two lakes in the outer Delta, and two coastal lakes on Richard's Island in 2015. The dissolved CH4 concentration, stable isotope content of CH4 (δ13C-CH4), and dissolved sulfate concentrations in bottom water from these lakes will be presented to better understand methane dynamics under the ice and over time. 2) Along with the time-series data, we will also present data from discrete samples collected from 40 lakes in the mid Delta during key time periods, before and immediately after the spring ice-out. By determining the CH4 dynamics throughout the year we hope to improve predictions of how CH4 emissions may change in a warming Arctic environment.

Meltwater and precipitation runoff to the North Atlantic, Arctic, and Gulf of Mexico from the Laurentide Ice Sheet and adjacent regions during the Younger Dryas

NASA Astrophysics Data System (ADS)

Teller, James T.

1990-12-01

Runoff from North America may have played a significant role in ocean circulation and climate change during the last deglaciation. Because the driving force behind such changes may have been related to salinity of the north flowing Atlantic Ocean conveyor circulation, it is critical to know the volume, timing, and location of fresh water entering the North Atlantic from the melting Laurentide Ice Sheet. During the Younger Dryas cold episode, 11,000-10,000 years B.P., there was a two-fold increase in the volume of meltwater plus precipitation runoff, to more than 1700 km³ yr-1, flowing through the St. Lawrence valley to the North Atlantic, mainly because retreating ice allowed the glacial Lake Agassiz basin to drain eastward into the Great Lakes at this time. There was a corresponding decline in discharge from Lake Agassiz through the Mississippi River to the Gulf of Mexico. Runoff to the Arctic Ocean also increased at about the beginning of the Younger Dryas, from 740 to 900 km³ yr-1, because of the capture of what is now the headwater region of the Mackenzie River watershed. This, in combination with rising sea level and warming climate, may have increased the amount of pack ice reaching the North Atlantic through the Norwegian Sea from the Arctic Ocean. At 10,000 years B.P., eastward overflow from the western interior of North America was blocked by advancing ice, again forcing overflow to the Gulf of Mexico and, possibly, to the northwest into the Arctic Ocean. Although total runoff to the oceans from all regions draining from the Laurentide Ice Sheet did not vary substantially between 12,000 and 9000 years B.P., if discharge to the Gulf of Mexico is excluded, fresh water reaching the North Atlantic averaged 4000 km³ yr-1 during the Younger Dryas, in contrast to 2870 km³ yr-1 just before this cold episode and 3440 km³ yr-1 just after it.

The 2012 Seti River flood disaster and alpine cryospheric hazards facing Pokhara, Nepal

NASA Astrophysics Data System (ADS)

Kargel, Jeffrey; Leonard, Gregory; Paudel, Lalu; Regmi, Dhananjay; Bajracharya, Samjwal; Fort, Monique; Joshi, Sharad; Poudel, Khagendra; Thapa, Bhabana; Watanabe, Teiji

2014-05-01

We have identified the likeliest cause of the Seti River disaster of May 5, 2012, in which a flash flood killed or left missing 72 people. A cascade of deadly physical Earth processes combined with imprudent habitation on the lowest flood terraces and floodplain. The process cascade started with rockfalls into the Seti River gorge (observed via repeat ASTER imaging). The last rockfall-one to several weeks prior to the disaster-affected a knickpoint in the Seti River gorge and impounded glacial meltwater and spring snowmelt. The trigger was a large rock/ice avalanche originating from cornice ice on Annapurna IV, where part of the mass was channeled into the impoundment reservoir. That violent ground-surge event, plus possibly an air blast caused by a violent gravity flow of airborne debris-then burst the rockfall dam. This was not a glacier lake outburst flood. Glaciers were involved in the disaster by supplying meltwater, which was impounded by the rockfall dam, by triggering the disaster with collapse of cornice ice, and by contributing ice to the landslide and outburst flood. Debuttressing of moraine debris and ancient glacial lake sediment by retreat and thinning of glaciers also may have played a role-this is the only possible indirect link of the disaster to climate change. The rockfall and avalanche mass movements occurred independently of climate change. The narrow and easily blocked Seti River gorge was a key factor in the 2012 disaster, and it remains a unique component of this physiographic setting. A similar flood in this area may happen by a different cascade of Earth surface processes. An enormous mass of ancient unconsolidated glaciolacustrine and moraine sediment-many cubic kilometers-was discovered and is vulnerable to production of debris flows and hyperconcentrated slurry flows. Some aggravating processes occurring in the Sabche Cirque are related to climate change. Glaciers in that area are melting, and small lakes are forming. Although the lakes were not implicated in the 2012 disaster, the possibility exists for a small glacial lake outburst flood to trigger a larger mass movement. Such a debris flow could reach Pokhara directly. More likely, a debris flow in the Sabche Cirque could form another temporary and potentially dangerous impoundment dam in the gorge. Furthermore, the type of rockfall blockage that produced 2012's natural impoundment reservoir is likely to happen repeatedly. Hence, there is a high capacity of the Earth system in this area to produce comparable or even bigger flash floods or mass flows. The likelihood of a further disaster is magnified by imprudent habitation of the river channel and lower floodplain. Of all the changes to the Pokhara Valley, human encroachment on the flood plain is the factor most related to increasing vulnerability, but it is also the one factor that could be remedied by a complete ban on construction on lower terraces, if that is politically feasible. Warning systems could help, but fairly relocating people in jeopardy would be more effective. Supported by NASA/USAID SERVIR Applied Sciences and USAID Climbers' Science.

Glacial geology of the Shingobee River headwaters area, north-central Minnesota

USGS Publications Warehouse

Melchior, Robert C.

2014-01-01

During middle and late Wisconsin time in the Shingobee River headwaters area, the Laurentide Wadena lobe, Hewitt and Itasca phases, produced terminal and ground moraine along with a variety of associated glacial features. The stratigraphic record is accessible and provides details of depositional mode as well as principal glacial events during the advance and retreat of middle and late Wisconsin ice tongues. Geomorphic features such as tunnel valleys, stream terraces, and postglacial stream cuts formed by erosional events persist to the present day. Middle Wisconsin Hewitt phase deposits are the oldest and include drumlins, ground moraine, boulder pavements, and outwash. Together, these deposits suggest a wet-based, periodically surging glacier in a subpolar thermal state. Regional permafrost and deposition from retreating ice are inferred between the end of the Hewitt phase and the advance of late Wisconsin Itasca phase ice. Itasca phase glaciation occurred as a contemporaneous pair of adjacent ice tongues whose contrasting moraine styles suggest independent flow modes. The western (Shingobee) portion of the Itasca moraine contains composite ridges, permafrost phenomena, hill-hole pairs, and debris flows. By contrast, eastern (Onigum) moraine deposits generally lack glaciotectonic features and consist almost exclusively of mud and debris flows. Near the end of the Itasca phase, large-scale hill-hole pairs developed in the Shingobee division, and debris flows from the Onigum division blocked the preexisting Shingobee tunnel valley to form glacial lake Willobee. Postglacial streams formed deep valleys as glacial lake Willobee catastrophically drained. Dates based on temperature trends in Greenland ice cores are proposed for prominent glacial events in the Shingobee area. This report proposes that Hewitt phase glaciation occurred between 27.2 and 23.6 kiloannum and Itasca phase glaciation between 22.8 and 14.7 kiloannum. Des Moines lobe (Younger Dryas) glaciation, which had only secondary effects on the Shingobee headwaters area, occurred between 13.5 and 11.6 kiloannum.

Variability and Change in the Canadian Cryosphere: A Canadian Science Contribution to International Polar Year

NASA Astrophysics Data System (ADS)

Walker, A. E.; Derksen, C.

2008-12-01

The cryosphere (snow, permafrost and seasonally frozen ground, ice caps and glaciers, sea-, river-, and lake ice) represents a significant feature of the Canadian landscape that impacts climate, hydrology, the economy and the daily lives of all Canadians, especially those living in northern communities. Over the past few decades significant changes have been observed in cryospheric elements (e.g. decreases in snow cover, glacier extent, sea ice cover) that have been attributed to a warming climate. This poster presentation will highlight initial scientific results from the approved Canadian International Polar Year project "Variability and Change in the Canadian Cryosphere" that is being led by Environment Canada and involves 33 co- investigators from government, academia and the private sector and links with international collaborators. This project builds on Canadian strengths in remote sensing, climate analysis and modeling with the overall objective to observe and understand the current state of the cryosphere in Canada and determine how fast it is changing and why. Research activities are focused on: (1) developing new satellite-based capabilities to provide information on the current state of the Canadian cryosphere during the IPY period; (2) placing current cryospheric conditions in the context of the historical record to document the magnitude of changes over the 50 years since the last International Polar Year (IGY 1957-1958); (3) characterizing and explaining the observed variability and changes in the context of the coupled climate cryosphere system; and (4) improving the representation of the cryosphere in Canadian land surface and climate models to provide current and future climate simulations of the cryosphere for climate impact studies. The project also includes several outreach activities to engage northern communities in cryospheric monitoring and incorporate traditional knowledge with remotely-sensed information to generate new maps on local river ice and sea ice conditions to assist residents in planning safe navigation routes.

Calculating mercury loading to the tidal Hudson River, New York, using rating curve and surrogate methodologies

USGS Publications Warehouse

Wall, G.R.; Ingleston, H.H.; Litten, S.

2005-01-01

Total mercury (THg) load in rivers is often calculated from a site-specific "rating-curve" based on the relation between THg concentration and river discharge along with a continuous record of river discharge. However, there is no physical explanation as to why river discharge should consistently predict THg or any other suspended analyte. THg loads calculated by the rating-curve method were compared with those calculated by a "continuous surrogate concentration" (CSC) method in which a relation between THg concentration and suspended-sediment concentration (SSC) is constructed; THg loads then can be calculated from the continuous record of SSC and river discharge. The rating-curve and CSC methods, respectively, indicated annual THg loads of 46.4 and 75.1 kg for the Mohawk River, and 52.9 and 33.1 kg for the upper Hudson River. Differences between the results of the two methods are attributed to the inability of the rating-curve method to adequately characterize atypical high flows such as an ice-dam release, or to account for hysteresis, which typically degrades the strength of the relation between stream discharge and concentration of material in suspension. ?? Springer 2005.

Investigating passage of ESA-listed juvenile fall Chinook salmon at Lower Granite Dam during winter when the fish bypass system is not operated. 2006 Annual Report

USGS Publications Warehouse

Tiffan, Kenneth F.; Kock, Tobias J.; Connor, William P.

2007-01-01

During the winter of 2005-06, we radio and PIT tagged and released 48 juvenile fall Chinook salmon to evaluate over-wintering behavior and dam passage in the lower Snake River, Washington. Fish were released at the upstream end of the Lower Granite Dam forebay in November and December 2005. Fixed radio telemetry detection sites located in forebay and tailrace areas of Lower Granite, Little Goose, Lower Monumental and Ice Harbor dams were used to monitor fish movements and dam passage through early-May 2006. Of the 48 fish released during our study, 39 (81 %) passed Lower Granite Dam and were detected at downstream detection sites, 29 (60%) passed Little Goose Dam, 25 (52%) passed Lower Monumental Dam, and 15 (31%) passed Ice Harbor Dam. Thirty-seven (95%), 23 (79%), 16 (64%), and 9 (60%) of the fish that passed Lower Granite, Little Goose, Lower Monumental, and Ice Harbor dams respectively, did so when the fish bypass system was not operated. Passage of tagged fish past lower Snake River dams generally declined during the winter, but increased again after bypass began in April. Fish residence times in reservoirs and forebays was lengthy during the winter (up to 118 d), and varied by reservoir and time of year. We observed no diel passage trends. Only 15 of the 48 fish were subsequently detected at a PIT-tag interrogation site the following spring. We believe that passage of overwintering juvenile fall Chinook salmon during winter is due more to chance than directed downstream movement. Since the primary route of passage during the winter is through powerhouse turbines, the potential exists for increased mortality for over-wintering juvenile fall Chinook salmon in the Snake River. Our findings also have implications for transportation studies of subyearling fall Chinook salmon in the Snake River. Specifically, the finding that some fish can pass undetected during the winter may bias smolt-to-adult return rate calculations that are typically used to measure the success of the aforementioned management actions.

Quaternary geology and geomorphology of the Dinosaur Provincial Park area and surrounding plains, Alberta, Canada: the identification of former glacial lobes, drainage diversions and meltwater flood tracks

NASA Astrophysics Data System (ADS)

Evans, David J. A.

2000-06-01

The Quaternary geology and geomorphology of the lower Red Deer River drainage basin, centred on the Dinosaur Provincial Park badlands, provides information on pre-Late Wisconsinan drainage patterns and the dynamics of former lobes of the Laurentide Ice Sheet in western Canada. Patterns of deglaciation, proglacial lake evolution and spillway incision are also reconstructed based upon the distribution of surface materials and glacial/glaciofluvial landforms. The Empress Group fluvial and glaciolacustrine sediments, which could be as young as 27 ka BP, infill the precursor Red Deer River and its tributaries and document the initial advance of glacier ice into southern Alberta. Glaciotectonic disturbance of older sediments and bedrock, the production of deformation tills and the construction of a megafluting complex and cupola hills record the advances of a glacier lobe centred over the study area. Stratified inter- and intra-till beds record pulses of subglacial meltwater between phases of subsole deformation. The thickening of tills towards the margin of the lobe represents a till wedge, an expected product of sediment advection by glaciers moving over deformable beds. The eastern margin of the glacier lobe is demarcated by the interlobate Suffield hummocky moraine belt which contains overprinted thrust ridges, which record diachronous oscillations of neighbouring lobes within the ice sheet. Proglacial and glaciofluvial sediments were deposited in the area in association with proglacial Lake Bassano/Patricia, which drained eastwards when the Suffield moraine was dissected by spillways. Changes in the size of glacial lake Bassano/Patricia are clearly documented by a sequence of spillway incisions which culminated in the erosion of scabland topography and the initiation of a new course for the Red Deer River, a 15 km southward diversion of the main channel. In distinct contrast to the documented incision histories of other small rivers in Alberta, One Tree Creek and Little Sandhill Creek did not start major incisions of the Quaternary sediments over buried valley positions until the late-Holocene when environmental conditions were characterized by higher precipitation.

An inventory and estimate of water stored in firn fields, glaciers, debris-covered glaciers, and rock glaciers in the Aconcagua River Basin, Chile

NASA Astrophysics Data System (ADS)

Janke, Jason R.; Ng, Sam; Bellisario, Antonio

2017-11-01

An inventory of firn fields, glaciers, debris-covered glaciers, and rock glaciers was conducted in the Aconcagua River Basin of the semiarid Andes of central Chile. A total of 916 landforms were identified, of which rock glaciers were the most abundant (669) and occupied the most total area. Glaciers and debris-covered glaciers were less numerous, but were about five times larger in comparison. The total area occupied by glaciers and debris-covered glaciers was roughly equivalent to the total area of rock glaciers. Debris-covered glaciers and rock glaciers were subcategorized into six ice-content classes based on interpretation of surface morphology with high-resolution satellite imagery. Over 50% of rock glaciers fell within a transitional stage; 85% of debris-covered glaciers were either fully covered or buried. Most landforms occupied elevations between 3500 and 4500 m. Glaciers and firn occurred at higher elevations compared to rock glaciers and debris-covered glaciers. Rock glaciers had a greater frequency in the northern part of the study area where arid climate conditions exist. Firn and glaciers were oriented south, debris-covered glaciers west, and rock glaciers southwest. An analysis of water contribution of each landform in the upper Andes of the Aconcagua River Basin was conducted using formulas that associate the size of the landforms to estimates of water stored. Minimum and maximum water storage was calculated based on a range of debris to ice content ratios for debris-covered glaciers and rock glaciers. In the Aconcagua River Basin, rock glaciers accounted for 48 to 64% of the water stored within the landforms analyzed; glaciers accounted for 15 to 25%; debris-covered glaciers were estimated at 15 to 19%; firn fields contained only about 5 to 8% of the water stored. Expansion of agriculture, prolonged drought, and removal of ice-rich landforms for mining have put additional pressure on already scarce water resources. To develop long-term, sustainable solutions, the importance of the water stored in rock glaciers or other alpine permafrost landforms, such as talus slopes, must be weighed against the economic value of mineral resources.

Landsat time series analysis documents beaver migration into permafrost landscapes of arctic Alaska

NASA Astrophysics Data System (ADS)

Jones, B. M.; Tape, K. D.; Nitze, I.; Arp, C. D.; Grosse, G.; Zimmerman, C. E.

2017-12-01

Landscape-scale impacts of climate change in the Arctic include increases in growing season length, shrubby vegetation, winter river discharge, snowfall, summer and winter water temperatures, and decreases in river and lake ice thickness. Combined, these changes may have created conditions that are suitable for beaver colonization of low Arctic tundra regions. We developed a semi-automated workflow that analyzes Landsat imagery time series to determine the extent to which beavers may have colonized permafrost landscapes in arctic Alaska since 1999. We tested this approach on the Lower Noatak, Wulik, and Kivalina river watersheds in northwest Alaska and identified 83 locations representing potential beaver activity. Seventy locations indicated wetting trends and 13 indicated drying trends. Verification of each site using high-resolution satellite imagery showed that 80 % of the wetting locations represented beaver activity (damming and pond formation), 11 % were unrelated to beavers, and 9 % could not readily be distinguished as being beaver related or not. For the drying locations, 31 % represented beaver activity (pond drying due to dam abandonment), 62 % were unrelated to beavers, and 7 % were undetermined. Comparison of the beaver activity database with historic aerial photography from ca. 1950 and ca. 1980 indicates that beavers have recently colonized or recolonized riparian corridors in northwest Alaska. Remote sensing time series observations associated with the migration of beavers in permafrost landscapes in arctic Alaska include thermokarst lake expansion and drainage, thaw slump initiation, ice wedge degradation, thermokarst shore fen development, and possibly development of lake and river taliks. Additionally, beaver colonization in the Arctic may alter channel courses, thermal regimes, hyporheic flow, riparian vegetation, and winter ice regimes that could impact ecosystem structure and function in this region. In particular, the combination of beaver activity and permafrost dynamics may play an important role in the formation of habitats conducive to colonization by Pacific salmon. Beaver activity in arctic tundra regions may amplify the effects of climate change on permafrost landscapes and lead to landscape-scale responses not currently being considered in ecosystem models.

Evaluate Status of Pacific Lamprey in the Clearwater River and Salmon River Drainages, Idaho, 2009 Technical Report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cochnauer, Tim; Claire, Christopher

2009-05-07

Pacific lamprey Lampetra tridentata have received little attention in fishery science until recently, even though abundance has declined significantly along with other anadromous fish species in Idaho. Pacific lamprey in Idaho have to navigate over eight lower Snake River and Columbia River hydroelectric facilities for migration downstream as juveniles to the Pacific Ocean and again as adults migrating upstream to their freshwater spawning grounds in Idaho. The number of adult Pacific lamprey annually entering the Snake River basin at Ice Harbor Dam has declined from an average of over 18,000 during 1962-1969 to fewer than 600 during 1998-2006. Based onmore » potential accessible streams and adult escapement over Lower Granite Dam on the lower Snake River, we estimate that no more than 200 Pacific lamprey adult spawners annually utilize the Clearwater River drainage in Idaho for spawning. We utilized electrofishing in 2000-2006 to capture, enumerate, and obtain biological information regarding rearing Pacific lamprey ammocoetes and macropthalmia to determine the distribution and status of the species in the Clearwater River drainage, Idaho. Present distribution in the Clearwater River drainage is limited to the lower sections of the Lochsa and Selway rivers, the Middle Fork Clearwater River, the mainstem Clearwater River, the South Fork Clearwater River, and the lower 7.5 km of the Red River. In 2006, younger age classes were absent from the Red River.« less

Uranium isotopes (U-234/U-238) in rivers of the Yukon Basin (Alaska and Canada) as an aid in identifying water sources, with implications for monitoring hydrologic change in arctic regions

USGS Publications Warehouse

Kraemer, Thomas F.; Brabets, Timothy P.

2012-01-01

The ability to detect hydrologic variation in large arctic river systems is of major importance in understanding and predicting effects of climate change in high-latitude environments. Monitoring uranium isotopes (234U and 238U) in river water of the Yukon River Basin of Alaska and northwestern Canada (2001–2005) has enhanced the ability to identify water sources to rivers, as well as detect flow changes that have occurred over the 5-year study. Uranium isotopic data for the Yukon River and major tributaries (the Porcupine and Tanana rivers) identify several sources that contribute to river flow, including: deep groundwater, seasonally frozen river-valley alluvium groundwater, and high-elevation glacial melt water. The main-stem Yukon River exhibits patterns of uranium isotopic variation at several locations that reflect input from ice melt and shallow groundwater in the spring, as well as a multi-year pattern of increased variability in timing and relative amount of water supplied from higher elevations within the basin. Results of this study demonstrate both the utility of uranium isotopes in revealing sources of water in large river systems and of incorporating uranium isotope analysis in long-term monitoring of arctic river systems that attempt to assess the effects of climate change.

Land Ice Freshwater Budget of the Arctic and North Atlantic Oceans: 1. Data, Methods, and Results

NASA Astrophysics Data System (ADS)

Bamber, J. L.; Tedstone, A. J.; King, M. D.; Howat, I. M.; Enderlin, E. M.; van den Broeke, M. R.; Noel, B.

2018-03-01

The freshwater budget of the Arctic and sub-polar North Atlantic Oceans has been changing due, primarily, to increased river runoff, declining sea ice and enhanced melting of Arctic land ice. Since the mid-1990s this latter component has experienced a pronounced increase. We use a combination of satellite observations of glacier flow speed and regional climate modeling to reconstruct the land ice freshwater flux from the Greenland ice sheet and Arctic glaciers and ice caps for the period 1958-2016. The cumulative freshwater flux anomaly exceeded 6,300 ± 316 km3 by 2016. This is roughly twice the estimate of a previous analysis that did not include glaciers and ice caps outside of Greenland and which extended only to 2010. From 2010 onward, the total freshwater flux is about 1,300 km3/yr, equivalent to 0.04 Sv, which is roughly 40% of the estimated total runoff to the Arctic for the same time period. Not all of this flux will reach areas of deep convection or Arctic and Sub-Arctic seas. We note, however, that the largest freshwater flux anomalies, grouped by ocean basin, are located in Baffin Bay and Davis Strait. The land ice freshwater flux displays a strong seasonal cycle with summer time values typically around five times larger than the annual mean. This will be important for understanding the impact of these fluxes on fjord circulation, stratification, and the biogeochemistry of, and nutrient delivery to, coastal waters.

46 CFR 45.187 - Weather limitations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Weather limitations. 45.187 Section 45.187 Shipping... River Barges on Lake Michigan Routes § 45.187 Weather limitations. (a) Tows on the Burns Harbor route must operate during fair weather conditions only. (b) The weather limits (ice conditions, wave height...

46 CFR 45.187 - Weather limitations.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Weather limitations. 45.187 Section 45.187 Shipping... River Barges on Lake Michigan Routes § 45.187 Weather limitations. (a) Tows on the Burns Harbor route must operate during fair weather conditions only. (b) The weather limits (ice conditions, wave height...

46 CFR 45.187 - Weather limitations.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Weather limitations. 45.187 Section 45.187 Shipping... River Barges on Lake Michigan Routes § 45.187 Weather limitations. (a) Tows on the Burns Harbor route must operate during fair weather conditions only. (b) The weather limits (ice conditions, wave height...

46 CFR 45.187 - Weather limitations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Weather limitations. 45.187 Section 45.187 Shipping... River Barges on Lake Michigan Routes § 45.187 Weather limitations. (a) Tows on the Burns Harbor route must operate during fair weather conditions only. (b) The weather limits (ice conditions, wave height...

46 CFR 45.187 - Weather limitations.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Weather limitations. 45.187 Section 45.187 Shipping... River Barges on Lake Michigan Routes § 45.187 Weather limitations. (a) Tows on the Burns Harbor route must operate during fair weather conditions only. (b) The weather limits (ice conditions, wave height...

Radar backscatter measurements from Arctic sea ice during the fall freeze-up

NASA Technical Reports Server (NTRS)

Beaven, S.; Gogineni, S. P.; Shanableh, M.; Gow, A.; Tucker, W.; Jezek, K.

1993-01-01

Radar backscatter measurements from sea ice during the fall freeze-up were performed by the United States Coast Guard Icebreaker Polar Star as a part of the International Arctic Ocean Expedition (IAOE'91) from Aug. to Sep. 1991. The U.S. portion of the experiment took place on board the Polar Star and was referred to as TRAPOLEX '91 (Transpolar expedition) by some investigators. Before prematurely aborting its mission because of mechanical failure of her port shaft, the Polar Star reached 84 deg 57 min N latitude at 35 deg E longitude. The ship was in the ice (greater than 50 percent coverage) from 14 Aug. until 3 Sep. and was operational for all but 6 days due to two instances of mechanical problems with the port shaft. The second was fatal to the ship's participation in the expedition. During the expedition, radar backscatter was measured at C-band under a variety of conditions. These included measurements from young ice types as well as from multiyear and first-/second-year sea ice during the fall freeze-up. The sea ice types were determined by measurement of the ice properties at several of the stations and by visual inspection on others. Radar backscatter measurements were performed over a large portion of the ship's transit into the Arctic ice pack. These were accompanied by in situ sea ice property characterization by the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) at several stations and, when snow was present, its properties were documented by The Microwave Group, Ottawa River (MWG).

Simulation of multistatic and backscattering cross sections for airborne radar

NASA Astrophysics Data System (ADS)

Biggs, Albert W.

1986-07-01

In order to determine susceptibilities of airborne radar to electronic countermeasures and electronic counter-countermeasures simulations of multistatic and backscattering cross sections were developed as digital modules in the form of algorithms. Cross section algorithms are described for prolate (cigar shape) and oblate (disk shape) spheroids. Backscattering cross section algorithms are also described for different categories of terrain. Backscattering cross section computer programs were written for terrain categorized as vegetation, sea ice, glacial ice, geological (rocks, sand, hills, etc.), oceans, man-made structures, and water bodies. PROGRAM SIGTERRA is a file for backscattering cross section modules of terrain (TERRA) such as vegetation (AGCROP), oceans (OCEAN), Arctic sea ice (SEAICE), glacial snow (GLASNO), geological structures (GEOL), man-made structures (MAMMAD), or water bodies (WATER). AGCROP describes agricultural crops, trees or forests, prairies or grassland, and shrubs or bush cover. OCEAN has the SLAR or SAR looking downwind, upwind, and crosswind at the ocean surface. SEAICE looks at winter ice and old or polar ice. GLASNO is divided into a glacial ice and snow or snowfields. MANMAD includes buildings, houses, roads, railroad tracks, airfields and hangars, telephone and power lines, barges, trucks, trains, and automobiles. WATER has lakes, rivers, canals, and swamps. PROGRAM SIGAIR is a similar file for airborne targets such as prolate and oblate spheroids.

White sturgeon spawning areas in the lower Snake River

USGS Publications Warehouse

Parsley, M.J.; Kappenman, K.M.

2000-01-01

We documented 17 white sturgeon Acipenser transmontanus spawning locations in the Snake River from the mouth to Lower Granite Dam (river km 0 to 173). Spawning locations were determined by the collection of fertilized eggs on artificial substrates or in plankton nets. We collected 245 eggs at seven locations in McNary Reservoir, 22 eggs at three locations in Ice Harbor Reservoir, 30 eggs from two locations in Lower Monumental Reservoir, and 464 eggs at five locations in Little Goose Reservoir. All 17 locations were in high water velocity areas and between 1.0 and 7.0 km downstream from a hydroelectric dam. The documentation of spawning areas is important because this habitat is necessary to maintain natural and viable populations.

Probability based hydrologic catchments of the Greenland Ice Sheet

NASA Astrophysics Data System (ADS)

Hudson, B. D.

2015-12-01

Greenland Ice Sheet melt water impacts ice sheet flow dynamics, fjord and coastal circulation, and sediment and biogeochemical fluxes. Melt water exiting the ice sheet also is a key term in its mass balance. Because of this, knowledge of the area of the ice sheet that contributes melt water to a given outlet (its hydrologic catchment) is important to many ice sheet studies and is especially critical to methods using river runoff to assess ice sheet mass balance. Yet uncertainty in delineating ice sheet hydrologic catchments is a problem that is rarely acknowledged. Ice sheet catchments are delineated as a function of both basal and surface topography. While surface topography is well known, basal topography is less certain because it is dependent on radar surveys. Here, I a present a Monte Carlo based approach to delineating ice sheet catchments that quantifies the impact of uncertain basal topography. In this scheme, over many iterations I randomly vary the ice sheet bed elevation within published error bounds (using Morlighem et al., 2014 bed and bed error datasets). For each iteration of ice sheet bed elevation, I calculate the hydraulic potentiometric surface and route water over its path of 'steepest' descent to delineate the catchment. I then use all realizations of the catchment to arrive at a probability map of all major melt water outlets in Greenland. I often find that catchment size is uncertain, with small, random perturbations in basal topography leading to large variations in catchments size. While some catchments are well defined, others can double or halve in size within published basal topography error bars. While some uncertainty will likely always remain, this work points to locations where studies of ice sheet hydrology would be the most successful, allows reinterpretation of past results, and points to where future radar surveys would be most advantageous.

Soil Organic Carbon Storage in Five Different Arctic Permafrost Environments

NASA Astrophysics Data System (ADS)

Fuchs, M.; Grosse, G.; Jones, B. M.; Maximov, G.; Strauss, J.

2016-12-01

Arctic river deltas and ice-rich permafrost regions are highly dynamic environments which will be strongly affected by future climate change. Rapid thaw of permafrost (thermokarst and thermo-erosion) may cause significant mobilization of organic carbon, which is assumed to be stored in large amounts in Arctic river deltas and ice-rich permafrost. This study presents and compares new data on organic carbon storage in thermokarst landforms and Arctic river delta deposits for the first two meters of soils for five different study areas in Alaska and Siberia. The sites include the Ikpikpuk river delta (North Alaska), Fish Creek river delta (North Alaska), Teshekpuk Lake Special Area (North Alaska), Sobo-Sise Island (Lena river delta, Northeast Siberia), and Bykovsky Peninsula (Northeast Siberia). Samples were taken with a SIPRE auger along transects covering the main geomorphological landscape units in the study regions. Our results show a high variability in soil organic carbon storage among the different study sites. The studied profiles in the Teshekpuk Lake Special Area - dominated by drained thermokarst lake basins - contained significantly more carbon than the other areas. The Teshekpuk Lake Special Area contains 44 ± 9 kg C m-2 (0-100 cm, mean value of profiles ± Std dev) compared to 20 ± 7 kg C m-2 kg for Sobo-Sise Island - a Yedoma dominated island intersected by thaw lake basins and 24 ± 6 kg C m-2 for the deltaic dominated areas (Fish Creek and Ikpikpuk). However, especially for the Ikpikpuk river delta, a significant amount of carbon (25 ± 9 kg C m-2) is stored in the second meter of soil (100-200cm). This study shows the importance of including deltaic and thermokarst-affected landscapes as considerable carbon pools, but indicates that these areas are heterogeneous in terms of organic carbon storage and cannot be generalized. As a next step, the site-level carbon stocks will be upscaled to the landscape level using remote sensing-based land cover classifications to calculate the carbon storage potential for Arctic deltas and larger thermokarst regions, to estimate mobilization potentials from thermokarst and thermo-erosion, and to provide input data for future permafrost carbon feedback models.

Whole-stream metabolism of a perennial spring-fed aufeis field in Alaska, with coincident surface and subsurface flow

NASA Astrophysics Data System (ADS)

Hendrickson, P. J.; Gooseff, M. N.; Huryn, A. D.

2017-12-01

Aufeis (icings or naleds) are seasonal arctic and sub-arctic features that accumulate through repeated overflow and freeze events of river or spring discharge. Aufeis fields, defined as the substrate on which aufeis form and the overlaying ice, have been studied to mitigate impacts on engineering structures; however, ecological characteristics and functions of aufeis fields are poorly understood. The perennial springs that supply warm water to aufeis fields create unique fluvial habitats, and are thought to act as winter and summer oases for biota. To investigate ecosystem function, we measured whole-stream metabolism at the Kuparuk River Aufeis (North Slope, AK), a large ( 5 km2) field composed of cobble substrate and predominately subsurface flow dynamics. The single-station open channel diel oxygen method was utilized at several dissolved oxygen (DO) stations located within and downstream of the aufeis field. DO loggers were installed in August 2016, and data downloaded summer 2017. Daily ecosystem respiration (ER), gross primary production (GPP) and reaeration rates were modeled using BASE, a package freely available in the open-source software R. Preliminary results support net heterotrophy during a two-week period of DO measurements in the fall season when minimum ice extent is observed. GPP, ER, and net metabolism are greater at the upstream reach near the spring source (P/R = 0.53), and decrease as flow moves downstream. As flow exits the aufeis field, surface and subsurface flow are incorporated into the metabolism model, and indicate the stream system becomes dependent on autochthonous production (P/R = 0.91). Current work is directed towards spring and summer discharge and metabolic parameter estimation, which is associated with maximum ice extent and rapid melting of the aufeis feature.

Environmental impact of melting buried ice blocks (North Poland)

NASA Astrophysics Data System (ADS)

Ott, F.; Slowinski, M. M.; Blaszkiewicz, M.; Brauer, A.; Noryskiewicz, B.; Tyszkowski, S.

2013-12-01

The aim of the research was to decipher the impacts of the role of dead ice melting on landscape evolution in the Lateglacial and early Holocene Central Europe. Here, we present the paleoecological results from the middle section of the Wda river which is located in northern Poland (Central Europe), on the outwash plain formed during the Pomeranian phase of the last (Vistulian) glacial period ca 16,000 14C yrs BP. The Wda river has a typical polygenetic valley in young glacial areas of the northern central European lowlands. We reconstructed environmental changes using biotic proxies (plant macrofossil and pollen analyses) and geomorphological investigations. In this study we focused on a short terrestrial sediment core (48 cm) representing four phases of landscape evolution: telmatic, lacustrine, lacustrine-fluvial and alluvial. Abrupt changes in lithology and sediment structures show rapid changes and threshold processes in environmental conditions. The AMS 14C dating of terrestrial plant remains reveals an age for the basal sediments of 11 223 × 23 cal yr BP and thus falls within the Preboreal biozone. Our results showed that existence of buried ice blocks in northern Poland even at the beginning of the Holocene is clear evidence that locally discontinuous permafrost still was present at that time. The results of our study prove a strong influence of melting buried ice blocks on the geomorphological development, hydrological changes in the catchment, and the biotic environment even in the early Holocene. The research was supported by the National Science Centre Poland (grants No. NN 306085037 and NCN 2011/01/B/ST10/07367). This study is a contribution to the Virtual Institute of Integrated Climate and Landscape Evolution (ICLEA) of the Helmholtz Association. Financial support by the COST Action ES0907 INTIMATE is gratefully acknowledged.

Upper Ocean Circulation in the Glacial Northeast Atlantic during Heinrich Stadials Ice-Sheet Retreat

NASA Astrophysics Data System (ADS)

Toucanne, S.; Soulet, G.; Bosq, M.; Marjolaine, S.; Zaragosi, S.; Bourillet, J. F.; Bayon, G.

2016-12-01

Intermediate ocean water variability is involved in climate changes over geological timescales. As a prominent example, changes in North Atlantic subsurface water properties (including warming) during Heinrich Stadials may have triggered the so-called Heinrich events through ice-shelf loss and attendant ice-stream acceleration. While the origin of Heinrich Stadials and subsequent iceberg calving remains controversial, paleoceanographic research efforts mainly focus on the deep Atlantic overturning, leaving the upper ocean largely unexplored. To further evaluate variability in upper ocean circulation and its possible relationship with ice-sheet instabilities, a depth-transect of eight cores (BOBGEO and GITAN-TANDEM cruises) from the Northeast Atlantic (down to 2 km water depth) have been used to investigate kinematic and chemical changes in the upper ocean during the last glacial period. Our results reveal that near-bottom flow speeds (reconstructed by using sortable silt mean grain-size and X-ray fluorescence core-scanner Zr/Rb ratio) and water-masses chemistry (carbon and neodymium isotopes performed on foraminifera) substantially changed in phase with the millennial-scale climate changes recognized in the ice-core records. Our results are compared with paleoceanographic reconstructions of the 'Western Boundary Undercurrent' in order to discuss regional hydrographic differences at both sides of the North Atlantic, as well as with the fluctuations of both the marine- (through ice-rafted debris) and terrestrial-terminating ice-streams (through meltwater discharges) of the circum-Atlantic ice-sheets. Particular attention will be given to the Heinrich Stadials and concomitant Channel River meltwater discharges into the Northeast Atlantic in response to the melting of the European Ice-Sheet. This comparison helps to disentangle the cryosphere-ocean interactions throughout the last ice age, and the sequence of events occurring in the course of the Heinrich Stadials.

Asynchronous ice lobe retreat and glacial Lake Bascom: Deglaciation of the Hoosic and Vermont valleys, southwestern Vermont

DOE Office of Scientific and Technical Information (OSTI.GOV)

Small, E.; Desimone, D.

Deglaciation of the Hoosic River drainage basin in southwestern Vermont was more complex than previously described. Detailed surficial mapping, stratigraphic relationships, and terrace levels/delta elevations reveal new details in the chronology of glacial Lake Bascom: (1) a pre-Wisconsinan proglacial lake was present in a similar position to Lake Bascom as ice advanced: (2) the northern margin of 275m (900 ft) glacial Lake Bascom extended 10 km up the Vermont Valley; (3) the 215m (705 ft) Bascom level was stable and long lived; (4) intermediate water planes existed between 215m and 190m (625 ft) levels; and (5) a separate ice tonguemore » existed in Shaftsbury Hollow damming a small glacial lake, here named glacial Lake Emmons. This information is used to correlate ice margins to different lake levels. Distance of ice margin retreat during a lake level can be measured. Lake levels are then used as control points on a Lake Bascom relative time line to compare rate of retreat of different ice tongues. Correlation of ice margins to Bascom levels indicates ice retreat was asynchronous between nearby tongues in southwestern Vermont. The Vermont Valley ice tongue retreated between two and four times faster than the Hoosic Valley tongue during the Bascom 275m level. Rate of retreat of the Vermont Valley tongue slowed to one-half of the Hoosic tongue during the 215m--190m lake levels. Factors responsible for varying rates of retreat are subglacial bedrock gradient, proximity to the Hudson-Champlain lobe, and the presence of absence of a calving margins. Asynchronous retreat produced splayed ice margins in southwestern Vermont. Findings from this study do not support the model of parallel, synchronous retreat proposed by many workers for this region.« less

Effects of ice and floods on vegetation in streams in cold regions: implications for climate change

PubMed Central

Lind, Lovisa; Nilsson, Christer; Weber, Christine

2014-01-01

Riparian zones support some of the most dynamic and species-rich plant communities in cold regions. A common conception among plant ecologists is that flooding during the season when plants are dormant generally has little effect on the survival and production of riparian vegetation. We show that winter floods may also be of fundamental importance for the composition of riverine vegetation. We investigated the effects of ice formation on riparian and in-stream vegetation in northern Sweden using a combination of experiments and observations in 25 reaches, spanning a gradient from ice-free to ice-rich reaches. The ice-rich reaches were characterized by high production of frazil and anchor ice. In a couple of experiments, we exposed riparian vegetation to experimentally induced winter flooding, which reduced the dominant dwarf-shrub cover and led to colonization of a species-rich forb-dominated vegetation. In another experiment, natural winter floods caused by anchor-ice formation removed plant mimics both in the in-stream and in the riparian zone, further supporting the result that anchor ice maintains dynamic plant communities. With a warmer winter climate, ice-induced winter floods may first increase in frequency because of more frequent shifts between freezing and thawing during winter, but further warming and shortening of the winter might make them less common than today. If ice-induced winter floods become reduced in number because of a warming climate, an important disturbance agent for riparian and in-stream vegetation will be removed, leading to reduced species richness in streams and rivers in cold regions. Given that such regions are expected to have more plant species in the future because of immigration from the south, the distribution of species richness among habitats can be expected to show novel patterns. PMID:25505542

Effects of ice and floods on vegetation in streams in cold regions: implications for climate change.

PubMed

Lind, Lovisa; Nilsson, Christer; Weber, Christine

2014-11-01

Riparian zones support some of the most dynamic and species-rich plant communities in cold regions. A common conception among plant ecologists is that flooding during the season when plants are dormant generally has little effect on the survival and production of riparian vegetation. We show that winter floods may also be of fundamental importance for the composition of riverine vegetation. We investigated the effects of ice formation on riparian and in-stream vegetation in northern Sweden using a combination of experiments and observations in 25 reaches, spanning a gradient from ice-free to ice-rich reaches. The ice-rich reaches were characterized by high production of frazil and anchor ice. In a couple of experiments, we exposed riparian vegetation to experimentally induced winter flooding, which reduced the dominant dwarf-shrub cover and led to colonization of a species-rich forb-dominated vegetation. In another experiment, natural winter floods caused by anchor-ice formation removed plant mimics both in the in-stream and in the riparian zone, further supporting the result that anchor ice maintains dynamic plant communities. With a warmer winter climate, ice-induced winter floods may first increase in frequency because of more frequent shifts between freezing and thawing during winter, but further warming and shortening of the winter might make them less common than today. If ice-induced winter floods become reduced in number because of a warming climate, an important disturbance agent for riparian and in-stream vegetation will be removed, leading to reduced species richness in streams and rivers in cold regions. Given that such regions are expected to have more plant species in the future because of immigration from the south, the distribution of species richness among habitats can be expected to show novel patterns.

Surface water hydrology and the Greenland Ice Sheet

NASA Astrophysics Data System (ADS)

Smith, L. C.; Yang, K.; Pitcher, L. H.; Overstreet, B. T.; Chu, V. W.; Rennermalm, A. K.; Cooper, M. G.; Gleason, C. J.; Ryan, J.; Hubbard, A.; Tedesco, M.; Behar, A.

2016-12-01

Mass loss from the Greenland Ice Sheet now exceeds 260 Gt/year, raising global sea level by >0.7 mm annually. Approximately two-thirds of this total mass loss is now driven by negative ice sheet surface mass balance (SMB), attributed mainly to production and runoff of meltwater from the ice sheet surface. This new dominance of runoff as a driver of GrIS total mass loss will likely persist owing to anticipated further increases in surface melting, reduced meltwater storage in firn, and the waning importance of dynamical mass losses (ice calving) as the ice sheets retreat from their marine-terminating margins. It also creates the need and opportunity for integrative research pairing traditional surface water hydrology approaches with glaciology. As one example, we present a way to measure supraglacial "runoff" (i.e. specific discharge) at the supraglacial catchment scale ( 101-102 km2), using in situ measurements of supraglacial river discharge and high-resolution satellite/drone mapping of upstream catchment area. This approach, which is standard in terrestrial hydrology but novel for ice sheet science, enables independent verification and improvement of modeled SMB runoff estimates used to project sea level rise. Furthermore, because current SMB models do not consider the role of fluvial watershed processes operating on the ice surface, inclusion of even a simple surface routing model materially improves simulations of runoff delivered to moulins, the critical pathways for meltwater entry into the ice sheet. Incorporating principles of surface water hydrology and fluvial geomorphology and into glaciological models will thus aid estimates of Greenland meltwater runoff to the global ocean as well as connections to subglacial hydrology and ice sheet dynamics.

Predicting the Future Contribution of Himalayan Debris-covered Glaciers to River Discharge: Advances and Challenges

NASA Astrophysics Data System (ADS)

Quincey, D. J.; Hubbard, B. P.; Klaar, M. J.; Miles, E.; Miles, K.; Rowan, A. V.; King, O.; Watson, C. S.

2017-12-01

The glaciers and snowfields of the Himalaya are the ultimate source for the many rivers that flow across the Asian subcontinent, but they are diminishing rapidly in the face of sustained climatic change. Predictions of how future river discharge may vary through space and time are hampered by two major knowledge gaps. First, simulations of glacier mass loss in high Asia are severely limited by data availability and assumptions made in the parameterisation of glacier models. Consequently, projections of glacier change vary widely; in Nepal for example, recent estimates of volumetric ice loss by AD2100 have ranged between 8% and 99%. A second major gap in knowledge lies in the coupling between glaciers and downstream areas, and specifically in quantifying the relative contributions of different sources to river flow. Although it is clear that ice and snow melt dominates flow for considerable distances downstream, how this contribution interacts with groundwater supplies with increasing distance from its source remains poorly understood. This presentation will review recent work that closes some of the knowledge gaps in understanding debris-covered glacier behaviour including new results from drilling work on the Khumbu Glacier in Nepal. Additionally, it will report on the outputs from an interdisciplinary study in the Annapurna region of Nepal, which is focussing specifically on disaggregating the relative contributions to flow using isotope-based hydrograph separations. It will finish by exploring the most likely drivers of future changes to water supply, including an evaluation of the impact of glacial lake development, and by identifying the main challenges for future related research.

Transformation of Upland Water and Carbon Dynamics by Thawing Permafrost in the Alaskan Interior

NASA Astrophysics Data System (ADS)

Ewing, S. A.; Paces, J. B.; O'Donnell, J. A.; Kanevskiy, M. Z.; Shur, Y.; Jorgenson, M. T.; Harden, J.; Aiken, G. R.; Striegl, R.

2009-05-01

Large arctic rivers can provide an integrated signal of regional permafrost thaw and associated carbon dynamics. A long-term (30-y) decrease in dissolved organic carbon (DOC) and increase in dissolved inorganic carbon in the Yukon River Basin (YRB) suggest increased flow through mineral soils as a result of permafrost thaw. We used U series isotopes to test for the influence of thaw on soil and surface waters in small upland catchments at two sites within the YRB. In natural waters, 234U/238U activity ratios exceed 1.00 (secular equilibrium) as a function of water-rock contact time. Previous work has shown that in major YRB rivers, seasonally and spatially variable 234U/238U ratios could indicate both groundwater inputs and permafrost thaw, with ratios ranging from 1.1 to 2.6. We show that 234U/238U ratios in soil and surface water from these small catchments span the range of values observed in the major rivers, and indicate greater influence of older water where the mineral soil and underlying sediment facilitate drainage and permafrost degradation. Analysis of deep, ice-rich loess permafrost cores (2-10 m) reveals that thaw of Pleistocene ice can release high concentrations of DOC (>1000 ppm) and ammonium in thaw waters. The age and chemical composition of these waters allows for improved prediction of downstream carbon dynamics upon thaw. Field observation of hillslope soil sequences indicates that both topography and mineral substrate influence the effects of thaw on water and carbon dynamics in small catchments.

Palaeolake isolation and biogeographical process of freshwater fishes in the Yellow River.

PubMed

Kang, Bin; Huang, Xiaoxia; Wu, Yunfei

2017-01-01

The Yellow River, one of the very few in the Earth, originated from many dispersive palaeolakes. Taking this unique advantage, we examined the roles of palaeolake isolation vs. geological processes vs. climate in determining current fish biogeographic pattern. We reviewed available data on fish species and their geographical distribution in the river, as well as palaeolake development, geological and climatic parameters. The 138 fish species recorded in the river could be divided into 8 biogeographic regions, corresponding to the distribution of palaeolakes and respective endemic species. Through variation partitioning analysis, palaeolake isolation was the most influential factor explaining 43.6% of the total variance on the current fish distribution. The Quaternary Ice Age produced a transitional distribution for fishes from the glacier to warm water, especially for the subfamily Schizothoracinae, which showed various degrees of specialisation along altitudes. We suggested that fish biogeography in the Yellow river was basically shaped by palaeolake isolation, and further carved under serials of geologic events and contemporary climate change.

Palaeolake isolation and biogeographical process of freshwater fishes in the Yellow River

PubMed Central

Wu, Yunfei

2017-01-01

The Yellow River, one of the very few in the Earth, originated from many dispersive palaeolakes. Taking this unique advantage, we examined the roles of palaeolake isolation vs. geological processes vs. climate in determining current fish biogeographic pattern. We reviewed available data on fish species and their geographical distribution in the river, as well as palaeolake development, geological and climatic parameters. The 138 fish species recorded in the river could be divided into 8 biogeographic regions, corresponding to the distribution of palaeolakes and respective endemic species. Through variation partitioning analysis, palaeolake isolation was the most influential factor explaining 43.6% of the total variance on the current fish distribution. The Quaternary Ice Age produced a transitional distribution for fishes from the glacier to warm water, especially for the subfamily Schizothoracinae, which showed various degrees of specialisation along altitudes. We suggested that fish biogeography in the Yellow river was basically shaped by palaeolake isolation, and further carved under serials of geologic events and contemporary climate change. PMID:28406965

Computing under-ice discharge: A proof-of-concept using hydroacoustics and the Probability Concept

NASA Astrophysics Data System (ADS)

Fulton, John W.; Henneberg, Mark F.; Mills, Taylor J.; Kohn, Michael S.; Epstein, Brian; Hittle, Elizabeth A.; Damschen, William C.; Laveau, Christopher D.; Lambrecht, Jason M.; Farmer, William H.

2018-07-01

Under-ice discharge is estimated using open-water reference hydrographs; however, the ratings for ice-affected sites are generally qualified as poor. The U.S. Geological Survey (USGS), in collaboration with the Colorado Water Conservation Board, conducted a proof-of-concept to develop an alternative method for computing under-ice discharge using hydroacoustics and the Probability Concept. The study site was located south of Minturn, Colorado (CO), USA, and was selected because of (1) its proximity to the existing USGS streamgage 09064600 Eagle River near Minturn, CO, and (2) its ease-of-access to verify discharge using a variety of conventional methods. From late September 2014 to early March 2015, hydraulic conditions varied from open water to under ice. These temporal changes led to variations in water depth and velocity. Hydroacoustics (tethered and uplooking acoustic Doppler current profilers and acoustic Doppler velocimeters) were deployed to measure the vertical-velocity profile at a singularly important vertical of the channel-cross section. Because the velocity profile was non-standard and cannot be characterized using a Power Law or Log Law, velocity data were analyzed using the Probability Concept, which is a probabilistic formulation of the velocity distribution. The Probability Concept-derived discharge was compared to conventional methods including stage-discharge and index-velocity ratings and concurrent field measurements; each is complicated by the dynamics of ice formation, pressure influences on stage measurements, and variations in cross-sectional area due to ice formation. No particular discharge method was assigned as truth. Rather one statistical metric (Kolmogorov-Smirnov; KS), agreement plots, and concurrent measurements provided a measure of comparability between various methods. Regardless of the method employed, comparisons between each method revealed encouraging results depending on the flow conditions and the absence or presence of ice cover. For example, during lower discharges dominated by under-ice and transition (intermittent open-water and under-ice) conditions, the KS metric suggests there is not sufficient information to reject the null hypothesis and implies that the Probability Concept and index-velocity rating represent similar distributions. During high-flow, open-water conditions, the comparisons are less definitive; therefore, it is important that the appropriate analytical method and instrumentation be selected. Six conventional discharge measurements were collected concurrently with Probability Concept-derived discharges with percent differences (%) of -9.0%, -21%, -8.6%, 17.8%, 3.6%, and -2.3%. This proof-of-concept demonstrates that riverine discharges can be computed using the Probability Concept for a range of hydraulic extremes (variations in discharge, open-water and under-ice conditions) immediately after the siting phase is complete, which typically requires one day. Computing real-time discharges is particularly important at sites, where (1) new streamgages are planned, (2) river hydraulics are complex, and (3) shifts in the stage-discharge rating are needed to correct the streamflow record. Use of the Probability Concept does not preclude the need to maintain a stage-area relation. Both the Probability Concept and index-velocity rating offer water-resource managers and decision makers alternatives for computing real-time discharge for open-water and under-ice conditions.

Computing under-ice discharge: A proof-of-concept using hydroacoustics and the Probability Concept

USGS Publications Warehouse

Fulton, John W.; Henneberg, Mark F.; Mills, Taylor J.; Kohn, Michael S.; Epstein, Brian; Hittle, Elizabeth A.; Damschen, William C.; Laveau, Christopher D.; Lambrecht, Jason M.; Farmer, William H.

2018-01-01

Under-ice discharge is estimated using open-water reference hydrographs; however, the ratings for ice-affected sites are generally qualified as poor. The U.S. Geological Survey (USGS), in collaboration with the Colorado Water Conservation Board, conducted a proof-of-concept to develop an alternative method for computing under-ice discharge using hydroacoustics and the Probability Concept.The study site was located south of Minturn, Colorado (CO), USA, and was selected because of (1) its proximity to the existing USGS streamgage 09064600 Eagle River near Minturn, CO, and (2) its ease-of-access to verify discharge using a variety of conventional methods. From late September 2014 to early March 2015, hydraulic conditions varied from open water to under ice. These temporal changes led to variations in water depth and velocity. Hydroacoustics (tethered and uplooking acoustic Doppler current profilers and acoustic Doppler velocimeters) were deployed to measure the vertical-velocity profile at a singularly important vertical of the channel-cross section. Because the velocity profile was non-standard and cannot be characterized using a Power Law or Log Law, velocity data were analyzed using the Probability Concept, which is a probabilistic formulation of the velocity distribution. The Probability Concept-derived discharge was compared to conventional methods including stage-discharge and index-velocity ratings and concurrent field measurements; each is complicated by the dynamics of ice formation, pressure influences on stage measurements, and variations in cross-sectional area due to ice formation.No particular discharge method was assigned as truth. Rather one statistical metric (Kolmogorov-Smirnov; KS), agreement plots, and concurrent measurements provided a measure of comparability between various methods. Regardless of the method employed, comparisons between each method revealed encouraging results depending on the flow conditions and the absence or presence of ice cover.For example, during lower discharges dominated by under-ice and transition (intermittent open-water and under-ice) conditions, the KS metric suggests there is not sufficient information to reject the null hypothesis and implies that the Probability Concept and index-velocity rating represent similar distributions. During high-flow, open-water conditions, the comparisons are less definitive; therefore, it is important that the appropriate analytical method and instrumentation be selected. Six conventional discharge measurements were collected concurrently with Probability Concept-derived discharges with percent differences (%) of −9.0%, −21%, −8.6%, 17.8%, 3.6%, and −2.3%.This proof-of-concept demonstrates that riverine discharges can be computed using the Probability Concept for a range of hydraulic extremes (variations in discharge, open-water and under-ice conditions) immediately after the siting phase is complete, which typically requires one day. Computing real-time discharges is particularly important at sites, where (1) new streamgages are planned, (2) river hydraulics are complex, and (3) shifts in the stage-discharge rating are needed to correct the streamflow record. Use of the Probability Concept does not preclude the need to maintain a stage-area relation. Both the Probability Concept and index-velocity rating offer water-resource managers and decision makers alternatives for computing real-time discharge for open-water and under-ice conditions.

Salinisation of rivers: an urgent ecological issue.

PubMed

Cañedo-Argüelles, Miguel; Kefford, Ben J; Piscart, Christophe; Prat, Narcís; Schäfer, Ralf B; Schulz, Claus-Jürgen

2013-02-01

Secondary salinisation of rivers and streams is a global and growing threat that might be amplified by climate change. It can have many different causes, like irrigation, mining activity or the use of salts as de-icing agents for roads. Freshwater organisms only tolerate certain ranges of water salinity. Therefore secondary salinisation has an impact at the individual, population, community and ecosystem levels, which ultimately leads to a reduction in aquatic biodiversity and compromises the goods and services that rivers and streams provide. Management of secondary salinization should be directed towards integrated catchment strategies (e.g. benefiting from the dilution capacity of the rivers) and identifying threshold salt concentrations to preserve the ecosystem integrity. Future research on the interaction of salinity with other stressors and the impact of salinization on trophic interactions and ecosystem properties is needed and the implications of this issue for human society need to be seriously considered. Copyright © 2012 Elsevier Ltd. All rights reserved.

Monitoring Snow and Land Ice Using Satellite data in the GMES Project CryoLand

NASA Astrophysics Data System (ADS)

Bippus, Gabriele; Nagler, Thomas

2013-04-01

The main objectives of the project "CryoLand - GMES Service Snow and Land Ice" are to develop, implement and validate services for snow, glaciers and lake and river ice products as a Downstream Service within the Global Monitoring for Environment and Security (GMES) program of the European Commission. CryoLand exploits Earth Observation data from current optical and microwave sensors and of the upcoming GMES Sentinel satellite family. The project prepares also the basis for the cryospheric component of the GMES Land Monitoring services. The CryoLand project team consists of 10 partner organisations from Austria, Finland, Norway, Sweden, Switzerland and Romania and is funded by the 7th Framework Program of the European Commission. The CryoLand baseline products for snow include fractional snow extent from optical satellite data, the extent of melting snow from SAR data, and coarse resolution snow water equivalent maps from passive microwave data. Experimental products include maps of snow surface wetness and temperature. The products range from large scale coverage at medium resolution to regional products with high resolution, in order to address a wide user community. Medium resolution optical data (e.g. MODIS, in the near future Sentinel-3) and SAR (ENVISAT ASAR, in the near future Sentinel-1) are the main sources of EO data for generating large scale products in near real time. For generation of regional products high resolution satellite data are used. Glacier products are based on high resolution optical (e.g. SPOT-5, in the near future Sentinel-2) and SAR (TerraSAR-X, in the near future Sentinel-1) data and include glacier outlines, mapping of glacier facies, glacier lakes and ice velocity. The glacier products are generated on users demand. Current test areas are located in the Alps, Norway, Greenland and the Himalayan Mountains. The lake and river ice products include ice extent and its temporal changes and snow extent on ice. The algorithms for these products are in development. One major task of CryoLand is the performance assessment of the products, which is carried out in different environments, climate zones and land cover types, selected jointly with users. Accuracy assessment is done for test areas using in-situ data and very high resolution satellite data. This presentation gives an overview on the processing lines and demonstration products for snow, glacier and lake ice parameters including examples of the product accuracy assessment. An important point of the CryoLand project is the use of advanced information technology, which is applied to process and distribute snow and land ice products in near real time.

Field testing and adaptation of a methodology to measure "in-stream" values in the Tongue River, northern Great Plains (NGP) region

USGS Publications Warehouse

Bovee, Ken D.; Gore, James A.; Silverman, Arnold J.

1978-01-01

A comprehensive, multi-component in-stream flow methodology was developed and field tested in the Tongue River in southeastern Montana. The methodology incorporates a sensitivity for the flow requirements of a wide variety of in-stream uses, and the flexibility to adjust flows to accommodate seasonal and sub-seasonal changes in the flow requirements for different areas. In addition, the methodology provides the means to accurately determine the magnitude of the water requirement for each in-stream use. The methodology can be a powerful water management tool in that it provides the flexibility and accuracy necessary in water use negotiations and evaluation of trade-offs. In contrast to most traditional methodologies, in-stream flow requirements were determined by additive independent methodologies developed for: 1) fisheries, including spawning, rearing, and food production; 2) sediment transport; 3) the mitigation of adverse impacts of ice; and 4) evapotranspiration losses. Since each flow requirement varied in important throughout the year, the consideration of a single in-stream use as a basis for a flow recommendation is inadequate. The study shows that the base flow requirement for spawning shovelnose sturgeon was 13.0 m3/sec. During the same period of the year, the flow required to initiate the scour of sediment from pools is 18.0 m3/sec, with increased scour efficiency occurring at flows between 20.0 and 25.0 m3/sec. An over-winter flow of 2.83 m3/sec. would result in the loss of approximately 80% of the riffle areas to encroachment by surface ice. At the base flow for insect production, approximately 60% of the riffle area is lost to ice. Serious damage to the channel could be incurred from ice jams during the spring break-up period. A flow of 12.0 m3/sec. is recommended to alleviate this problem. Extensive ice jams would be expected at the base rearing and food production levels. The base rearing flow may be profoundly influenced by the loss of streamflow to transpiration. Transpiration losses to riparian vegetation ranged from 0.78 m3/sec. in April, to 1.54 m3/sec. in July, under drought conditions. Requirement for irrigation were estimated to range from 5.56 m3/sec. in May to 7.97 m3/sec. in July, under drought conditions. It was concluded that flow requirements to satisfy monthly water losses to transpiration must be added to the base fishery flows to provide adequate protection to the resources in the lower reaches of the river. Integration of the in-stream requirements for various use components shows that a base flow of at least 23.6 m3/sec. must be reserved during the month of June to initiate scour of sediment from pools, provide spawning habitat to shovelnose sturgeon, and to accommodate water losses from the system. In comparison, a base flow of 3.85 m3/sec. would be required during early February to provide fish rearing habitat and insect productivity, and to prevent excessive loss of food production areas to surface ice formation. During mid to late February, a flow of 12 m3/sec. would be needed to facilitate ice break-up and prevent ice jams from forming. Following break-up, the base flow would again be 3.85 m3/sec. until the start of spawning season.

The hydrochemistry of glacial Ebba River (Petunia Bay, Central Spitsbergen): Groundwater influence on surface water chemistry

NASA Astrophysics Data System (ADS)

Dragon, Krzysztof; Marciniak, Marek; Szpikowski, Józef; Szpikowska, Grażyna; Wawrzyniak, Tomasz

2015-10-01

The article presents the investigation of surface water chemistry changes of the glacial Ebba River (Central Spitsbergen) during three melting seasons of 2008, 2009 and 2010. The twice daily water chemistry analyses allow recognition of the surface water chemistry differentiation. The surface water chemistry changes are related to the river discharge and changes in the influence of different water balance components during each melting season. One of the most important process that influence river water component concentration increase is groundwater inflow from active layer occurring on the valley area. The significance of this process is the most important at the end of the melting season when temperatures below 0 °C occur on glaciers (resulting in a slowdown of melting of ice and snow and a smaller recharge of the river by the water from the glaciers) while the flow of groundwater is still active, causing a relatively higher contribution of groundwater to the total river discharge. The findings presented in this paper show that groundwater contribution to the total polar river water balance is more important than previously thought and its recognition allow a better understanding of the hydrological processes occurring in a polar environment.

Food and water security in a changing arctic climate

NASA Astrophysics Data System (ADS)

White, Daniel M.; Gerlach, S. Craig; Loring, Philip; Tidwell, Amy C.; Chambers, Molly C.

2007-10-01

In the Arctic, permafrost extends up to 500 m below the ground surface, and it is generally just the top metre that thaws in summer. Lakes, rivers, and wetlands on the arctic landscape are normally not connected with groundwater in the same way that they are in temperate regions. When the surface is frozen in winter, only lakes deeper than 2 m and rivers with significant flow retain liquid water. Surface water is largely abundant in summer, when it serves as a breeding ground for fish, birds, and mammals. In winter, many mammals and birds are forced to migrate out of the Arctic. Fish must seek out lakes or rivers deep enough to provide good overwintering habitat. Humans in the Arctic rely on surface water in many ways. Surface water meets domestic needs such as drinking, cooking, and cleaning as well as subsistence and industrial demands. Indigenous communities depend on sea ice and waterways for transportation across the landscape and access to traditional country foods. The minerals, mining, and oil and gas industries also use large quantities of surface water during winter to build ice roads and maintain infrastructure. As demand for this limited, but heavily-relied-upon resource continues to increase, it is now more critical than ever to understand the impacts of climate change on food and water security in the Arctic.

Distribution of Some Rare and Trace Elements in Ice-Rafted Sediments in the Yermak Plateau Area, the Arctic Ocean

NASA Astrophysics Data System (ADS)

Shevchenko, V. P.; Maslov, A. V.; Stein, R.

2017-11-01

The distribution of V, Co, Ni, Sr, Nb and rare earth elements (REE) in ice-rafted sediments (IRS) collected in the Yermak Plateau area (the Arctic Ocean) during cruise ARK-XX/3 of the R/V Polarstern in September 2004 has been analyzed. It was determined that the Nb/V ratio in these IRS has an intermediate value between the average ratio values in suspended particulate matter of the Yenisei and Khatanga rivers and Mesozoic-Cenozoic basalts, on the one hand, and suspended matter of the Ob and Lena rivers and post-Archean Australian Shale (PAAS), on the other hand. The REE distribution demonstrates the same pattern. The IRS data points in Nb-Sr, Ni-Co, and Co-Sr and some other diagrams are close mainly to the average chemical composition of suspended particulate matter of the Ob and Lena rivers, i.e., waterways draining watersheds composed predominantly of sedimentary rocks. The Nb, Sr, Ni, and Co contents in the studied IRS samples are close to those in the PAAS. In accordance with this, we were able to conclude that the main provenance areas of the studied IRS samples are situated in the eastern part of the Laptev Sea and the East Siberian Sea, on shelf of which the erosion products of sedimentary and metamorphic rocks of the Verkhoyansk Fold Belt dominate.

Cryostratigraphy, sedimentology, and the late Quaternary evolution of the Zackenberg River delta, northeast Greenland

NASA Astrophysics Data System (ADS)

Gilbert, Graham L.; Cable, Stefanie; Thiel, Christine; Christiansen, Hanne H.; Elberling, Bo

2017-05-01

The Zackenberg River delta is located in northeast Greenland (74°30' N, 20°30' E) at the outlet of the Zackenberg fjord valley. The fjord-valley fill consists of a series of terraced deltaic deposits (ca. 2 km2) formed during relative sea-level (RSL) fall. We investigated the deposits using sedimentological and cryostratigraphic techniques together with optically stimulated luminescence (OSL) dating. We identify four facies associations in sections (4 to 22 m in height) exposed along the modern Zackenberg River and coast. Facies associations relate to (I) overriding glaciers, (II) retreating glaciers and quiescent glaciomarine conditions, (III) delta progradation in a fjord valley, and (IV) fluvial activity and niveo-aeolian processes. Pore, layered, and suspended cryofacies are identified in two 20 m deep ice-bonded sediment cores. The cryofacies distribution, together with low overall ground-ice content, indicates that permafrost is predominately epigenetic in these deposits. Fourteen OSL ages constrain the deposition of the cored deposits to between approximately 13 and 11 ka, immediately following deglaciation. The timing of permafrost aggradation was closely related to delta progradation and began following the subaerial exposure of the delta plain (ca. 11 ka). Our results reveal information concerning the interplay between deglaciation, RSL change, sedimentation, permafrost aggradation, and the timing of these events. These findings have implications for the timing and mode of permafrost aggradation in other fjord valleys in northeast Greenland.

Analysis of the origin of Aufeis feed-water on the arctic slope of Alaska

NASA Technical Reports Server (NTRS)

Hall, D. K.; Roswell, C. (Principal Investigator)

1980-01-01

The origin of water feeding large aufeis fields (overflow river ice) on the Arctic Slope of Alaska is analyzed. Field measurements of two large aufeis fields on the eastern Arctic Slope were taken during July of 1978 and 1979. Measurements of aufeis extent and distribution were made using LANDSAT Multispectral Scanner Subsystem (MSS) satellite data from 1973 through 1979. In addition, ice cores were analyzed in the laboratory. Results of the field and laboratory studies indicate that the water derived from aufeis melt water has a chemical composition different from the adjacent upstream river water. Large aufeis fields are found in association with springs and faults thus indicating a subterranean origin of the feed water. In addition, the maximum extent of large aufeis fields was not found to follow meteorological patterns which would only be expected if the origin of the feed water were local. It is concluded that extent of large aufeis in a given river channel on the Arctic Slope is controlled by discharge from reservoirs of groundwater. It seems probable that precipitation passes into limestone aquifers in the Brooks Range, through an interconnecting system of subterranean fractures in calcareous rocks and ultimately discharges into alluvial sediments on the coastal plain to form aufeis. It is speculated that only small aufeis patches are affected by local meteorological parameters in the months just prior to aufeis formation.

Glaciers and Sea Level Rise

NASA Image and Video Library

2017-12-08

Aerial view of the Sverdrup Glacier, a river of ice that flows from the interior of the Devon Island Ice Cap (Canada) into the ocean. To learn about the contributions of glaciers to sea level rise, visit: www.nasa.gov/topics/earth/features/glacier-sea-rise.html Credit: Alex Gardner, Clark University NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Hydrology signal from GRACE gravity data in the Nelson River basin, Canada: a comparison of two approaches

NASA Astrophysics Data System (ADS)

Li, Tanghua; Wu, Patrick; Wang, Hansheng; Jia, Lulu; Steffen, Holger

2018-03-01

The Gravity Recovery and Climate Experiment (GRACE) satellite mission measures the combined gravity signal of several overlapping processes. A common approach to separate the hydrological signal in previous ice-covered regions is to apply numerical models to simulate the glacial isostatic adjustment (GIA) signals related to the vanished ice load and then remove them from the observed GRACE data. However, the results of this method are strongly affected by the uncertainties of the ice and viscosity models of GIA. To avoid this, Wang et al. (Nat Geosci 6(1):38-42, 2013. https://doi.org/10.1038/NGEO1652; Geodesy Geodyn 6(4):267-273, 2015) followed the theory of Wahr et al. (Geophys Res Lett 22(8):977-980, 1995) and isolated water storage changes from GRACE in North America and Scandinavia with the help of Global Positioning System (GPS) data. Lambert et al. (Postglacial rebound and total water storage variations in the Nelson River drainage basin: a gravity GPS Study, Geological Survey of Canada Open File, 7317, 2013a, Geophys Res Lett 40(23):6118-6122, https://doi.org/10.1002/2013GL057973, 2013b) did a similar study for the Nelson River basin in North America but applying GPS and absolute gravity measurements. However, the results of the two studies in the Nelson River basin differ largely, especially for the magnitude of the hydrology signal which differs about 35%. Through detailed comparison and analysis of the input data, data post-processing techniques, methods and results of these two works, we find that the different GRACE data post-processing techniques may lead to this difference. Also the GRACE input has a larger effect on the hydrology signal amplitude than the GPS input in the Nelson River basin due to the relatively small uplift signal in this region. Meanwhile, the influence of the value of α , which represents the ratio between GIA-induced uplift rate and GIA-induced gravity-rate-of-change (before the correction for surface uplift), is more obvious in areas with high vertical uplift, but is smaller in the Nelson River basin. From Gaussian filtering of simulated data, we found that the magnitude of the peak gravity signal value can decrease significantly after Gaussian filtering with large average radius filter, but the effect in the Nelson River basin is rather small. More work is needed to understand the effect of amplitude restoration in the post-processing of GRACE g-dot signal. However, it is encouraging to find that both the methodologies of Wang et al. (2013, 2015) and Lambert et al. (2013a, b) can produce very similar results if their inputs are the same. This means that their methodologies can be applied to study the hydrology in other areas that are also affected by GIA provided that the effects of post-processing of their inputs are under control.

Upper Mississippi River System Environmental Management Program, Definite Project Report (R-6F) with Integrated Environmental Assessment (R-6F), Peoria Lake Enhancement, Peoria Pool, Illinois Waterway, River Miles 178.5 to 181, State of Illinois. Technical Appendices

DTIC Science & Technology

1990-06-01

pioneer bioengineering work has been conducted by Hollis H. Allen at WES in Corps reservoirs and on Corps projects on coastal shorelines, and by...several test locations to determine stability, growth of plants, effectiveness as a temporary breakwater, longevity , and ability to withstand ice and...Sampling to Characterize Size Demography and Density of Freshwater Mussel Communities." Bulletin of the American Malacological Union, Inc, 6: 49-54. J-40

Transient modeling of the ground thermal conditions using satellite data in the Lena River delta, Siberia

NASA Astrophysics Data System (ADS)

Westermann, Sebastian; Peter, Maria; Langer, Moritz; Schwamborn, Georg; Schirrmeister, Lutz; Etzelmüller, Bernd; Boike, Julia

2017-06-01

Permafrost is a sensitive element of the cryosphere, but operational monitoring of the ground thermal conditions on large spatial scales is still lacking. Here, we demonstrate a remote-sensing-based scheme that is capable of estimating the transient evolution of ground temperatures and active layer thickness by means of the ground thermal model CryoGrid 2. The scheme is applied to an area of approximately 16 000 km2 in the Lena River delta (LRD) in NE Siberia for a period of 14 years. The forcing data sets at 1 km spatial and weekly temporal resolution are synthesized from satellite products and fields of meteorological variables from the ERA-Interim reanalysis. To assign spatially distributed ground thermal properties, a stratigraphic classification based on geomorphological observations and mapping is constructed, which accounts for the large-scale patterns of sediment types, ground ice and surface properties in the Lena River delta. A comparison of the model forcing to in situ measurements on Samoylov Island in the southern part of the study area yields an acceptable agreement for the purpose of ground thermal modeling, for surface temperature, snow depth, and timing of the onset and termination of the winter snow cover. The model results are compared to observations of ground temperatures and thaw depths at nine sites in the Lena River delta, suggesting that thaw depths are in most cases reproduced to within 0.1 m or less and multi-year averages of ground temperatures within 1-2 °C. Comparison of monthly average temperatures at depths of 2-3 m in five boreholes yielded an RMSE of 1.1 °C and a bias of -0.9 °C for the model results. The highest ground temperatures are calculated for grid cells close to the main river channels in the south as well as areas with sandy sediments and low organic and ice contents in the central delta, where also the largest thaw depths occur. On the other hand, the lowest temperatures are modeled for the eastern part, which is an area with low surface temperatures and snow depths. The lowest thaw depths are modeled for Yedoma permafrost featuring very high ground ice and soil organic contents in the southern parts of the delta. The comparison to in situ observations indicates that transient ground temperature modeling forced by remote-sensing data is generally capable of estimating the thermal state of permafrost (TSP) and its time evolution in the Lena River delta. The approach could hence be a first step towards remote detection of ground thermal conditions and active layer thickness in permafrost areas.

75 FR 12735 - Draft Environmental Impact Statement (DEIS) for Resumption of Year-Round Firing Opportunities at...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-17

... until the discovery in 1990 that white phosphorus (a substance contained in certain Army munitions... when the ice is sufficiently thick to eliminate the risk of disturbing any underlying white phosphorus... white phosphorus from the local ecosystem. Active CERCLA cleanup at Eagle River Flats is scheduled for...

24. Photographic copy of photograph, 1930 (print located at Lockmaster's ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

24. Photographic copy of photograph, 1930 (print located at Lockmaster's House, Starved Rock Lock and Dam, near Utica, Illinois). DETAIL OF COMPLETED DAM SHOWING (LEFT TO RIGHT) TAINTER GATE, ICE, CHUTE, AND VERTICAL LIFT GATE WITH ALL GATES RAISED. - Starved Rock Locks & Dam, Illinois Waterway River mile 231, Peru, La Salle County, IL

Alaska's forest resource.

Treesearch

O. Keith Hutchison

1968-01-01

Alaska's romantic past includes the magnetic lure of gold; the mad stampede to strike it rich; success and heartbreak; men and animals battling snow, ice, spring breakup, insects, and loneliness; dog teams at work and on desperate missions; river steamers battling the Yukon; bush pilots performing miraculous flights; and hordes of salmon taken by traps and seine...

Chlorine-36 and cesium-137 in ice-core samples from mid-latitude glacial sites in the Northern Hemisphere

USGS Publications Warehouse

Green, J.R.; Cecil, L.D.; Synal, H.-A.; Kreutz, K.J.; Wake, C.P.; Naftz, D.L.; Frape, S.K.

2000-01-01

Chlorine-36 (36Cl) concentrations, 36Cl/Cl ratios, and 36Cl fluxes in ice-core samples collected from the Upper Fremont Glacier (UFG) in the Wind River Mountain Range, Wyoming, United States and the Nangpai Gosum Glacier (NGG) in the Himalayan Mountains, Nepal, were determined and compared with published results from the Dye-3 ice-core drilling site on the Greenland Ice Sheet. Cesium-137 (137Cs) concentrations in the NGG also were determined. The background fluxes for 36Cl for each glacial site were similar: (1.6??0.3)??10-2 atoms/cm2 s for the UFG samples, (0.7??0.1)??10-2 atoms/cm2 s for the NGG samples, and (0.4??0.1)??10-2 atoms/cm2 s for the Dye-3 samples. The 36Cl fluxes in ice that was deposited as snow during peak atmospheric nuclear weapon test (1957-1958) were (33??1)??10-2 atoms/cm2 s for the UFG site, (291??3)??10-2 atoms/cm2 s for the NGG site, and (124??5)??10-2 atoms/ cm2 s for the Dye-3 site. A weapon test period 137Cs concentration of 0.79??0.05 Bq/kg in the NGG ice core also was detected in the same section of ice that contained the largest 36Cl concentration. ?? 2000 Elsevier Science B.V. All rights reserved.

Extracting Hydrologic Understanding from the Unique Space-time Sampling of the Surface Water and Ocean Topography (SWOT) Mission

NASA Astrophysics Data System (ADS)

Nickles, C.; Zhao, Y.; Beighley, E.; Durand, M. T.; David, C. H.; Lee, H.

2017-12-01

The Surface Water and Ocean Topography (SWOT) satellite mission is jointly developed by NASA, the French space agency (CNES), with participation from the Canadian and UK space agencies to serve both the hydrology and oceanography communities. The SWOT mission will sample global surface water extents and elevations (lakes/reservoirs, rivers, estuaries, oceans, sea and land ice) at a finer spatial resolution than is currently possible enabling hydrologic discovery, model advancements and new applications that are not currently possible or likely even conceivable. Although the mission will provide global cover, analysis and interpolation of the data generated from the irregular space/time sampling represents a significant challenge. In this study, we explore the applicability of the unique space/time sampling for understanding river discharge dynamics throughout the Ohio River Basin. River network topology, SWOT sampling (i.e., orbit and identified SWOT river reaches) and spatial interpolation concepts are used to quantify the fraction of effective sampling of river reaches each day of the three-year mission. Streamflow statistics for SWOT generated river discharge time series are compared to continuous daily river discharge series. Relationships are presented to transform SWOT generated streamflow statistics to equivalent continuous daily discharge time series statistics intended to support hydrologic applications using low-flow and annual flow duration statistics.

Mammoths inside the Alps during the last glacial period: Radiocarbon constraints from Austria and palaeoenvironmental implications

NASA Astrophysics Data System (ADS)

Spötl, Christoph; Reimer, Paula J.; Göhlich, Ursula B.

2018-06-01

This study examines remains of the woolly mammoth (Mammuthus primigenius) found inside the Austrian Alps, an area occupied by an extensive ice-stream network during the Last Glacial Maximum. The data demonstrate that these cold steppe-adapted animals locally migrated several tens of kilometers into alpine valleys. Radiocarbon analyses constrain the age of these fossils to the first half of Marine Isotope Stage 3, documenting ice-free conditions in major valleys at that time. We also provide a list of all traceable Austrian sites of Mammuthus primigenius, totaling about 230 localities, compiled through 15 museums and collections in Austria. The vast majority of these findings are from the corridors of the Danube and Mur rivers and their tributaries and the adjacent loess-covered foreland of the Alps, areas that were never ice-covered during Pleistocene glaciations.

The Coolest Landscape on Mars or Earth

NASA Image and Video Library

2016-12-07

Many Martian landscapes contain features that are familiar to ones we find on Earth, like river valleys, cliffs, glaciers and volcanos. However, Mars has an exotic side too, with landscapes that are alien to Earthlings. This image shows one of these exotic locales at the South Pole. The polar cap is made from carbon dioxide (dry ice), which does not occur naturally on the Earth. The circular pits are holes in this dry ice layer that expand by a few meters each Martian year. New dry ice is constantly being added to this landscape by freezing directly out of the carbon dioxide atmosphere or falling as snow. Freezing out the atmosphere like this limits how cold the surface can get to the frost point at -130 degrees Celsius (-200 F). Nowhere on Mars can ever get any colder this, making this this coolest landscape on Earth and Mars combined. http://photojournal.jpl.nasa.gov/catalog/PIA21216

Correlation of climate cycles in middle Mississippi Valley loess and Greenland ice

USGS Publications Warehouse

Wang, Hongfang; Hughes, R.E.; Steele, J.D.; Lepley, S.W.; Tian, J.

2003-01-01

Two complete late Wisconsin loess successions in the middle Mississippi River Valley reveal 39 and 41 alternating paleosol A- and C-horizons. Striking changes in soil color, iron content, and carbonate content define four major and two minor paleosol A-horizon complexes, which were interpreted to represent Wisconsin interstadials 1, 2, 3, 4, and semiinterstadials 1.5 and 2.5, respectively. The timing of Wisconsin interstadials matches that of corresponding Greenland interstadials. Midcontinent loess and Greenland ice records as well as rates of atmospheric 14C production have periodicities in common, suggesting a solar influence. Only a persistent heat and moisture supply could produce prominent paleosol complexes near the continental ice margin. This record suggests that El Nin??o-Southern Oscillation variability has amplified solar forcing, and resultant tropical heat and moisture transport played a significant role in millennial- and centennial-scale climate cycles during the late Wisconsin glaciation over the Northern Hemisphere.

Trends in the Timing and Magnitude of Ice-Jam Floods in Canada.

PubMed

Rokaya, Prabin; Budhathoki, Sujata; Lindenschmidt, Karl-Erich

2018-04-11

Ice-jam floods (IJFs) are important hydrological and hydraulic events in the northern hemisphere that are of major concern for citizens, authorities, insurance companies and government agencies. In recent years, there have been advances in assessing and quantifying climate change impacts on river ice processes, however, an understanding of climate change and regulation impacts on the timing and magnitude of IJFs remains limited. This study presents a global overview of IJF case studies and discusses IJF risks in North America, one of the most IJF prone regions according to literature. Then an assessment of shifts in the timing and magnitude of IJFs in Canada is presented analyzing flow data from 1107 hydrometric stations across Canada for the period from 1903 to 2015. The analyses show clear signals of climate change and regulation impacts in the timing and magnitude of IJFs, particularly in small basins.

Mass loss on Himalayan glacier endangers water resources

NASA Astrophysics Data System (ADS)

Kehrwald, Natalie M.; Thompson, Lonnie G.; Tandong, Yao; Mosley-Thompson, Ellen; Schotterer, Ulrich; Alfimov, Vasily; Beer, Jürg; Eikenberg, Jost; Davis, Mary E.

2008-11-01

Ice cores drilled from glaciers around the world generally contain horizons with elevated levels of beta radioactivity including 36Cl and 3H associated with atmospheric thermonuclear bomb testing in the 1950s and 1960s. Ice cores collected in 2006 from Naimona'nyi Glacier in the Himalaya (Tibet) lack these distinctive marker horizons suggesting no net accumulation of mass (ice) since at least 1950. Naimona'nyi is the highest glacier (6050 masl) documented to be losing mass annually suggesting the possibility of similar mass loss on other high-elevation glaciers in low and mid-latitudes under a warmer Earth scenario. If climatic conditions dominating the mass balance of Naimona'nyi extend to other glaciers in the region, the implications for water resources could be serious as these glaciers feed the headwaters of the Indus, Ganges, and Brahmaputra Rivers that sustain one of the world's most populous regions.

JPSS Support to the Arctic Testbed

NASA Astrophysics Data System (ADS)

Layns, A. L.

2017-12-01

The Joint Polar Satellite System (JPSS) Proving Ground and Risk Reduction (PGRR) program facilitates initiatives to increase or improve the use and value of JPSS data products in user products, services, and application or service areas. Building on the success of the Fire and Smoke, River Ice and Flooding, and Sounding initiatives, the JPSS Arctic Initiative is the latest endeavor of the JPSS PGRR program to increase of the use of JPSS atmospheric and cryosphere products to improve NOAA's products and services in the Arctic. The major participants in the Arctic Initiative to date are the JPSS program office, National Ice Center (NIC), National Weather Service (NWS) Alaska Sea Ice Program (ASIP), and the National Environmental Satellite, Data, and Information Service (NESDIS) Center for Satellite Applications and Research (STAR). This paper will outline the initiative, the potential benefits of the JPSS data products in the Arctic, and the plans for a product demonstration in 2018 within the NOAA Arctic Testbed.

Greenland as seen by the STS-66 shuttle Atlantis

NASA Technical Reports Server (NTRS)

1994-01-01

This north-looking view of southwestern Greenland was taken in November, 1994, and shows numerous indentations, many of which contain small settlements. These fjords were carved by the glaciers of the last ice age 10,000 years ago. Even today, the ice in the center of Greenland is nearly 3,500 meters (11,000 feet) thick and great rivers of ice continuously flow down toward the sea, where they melt or break off as icebergs. Some Icebergs exceed the size of small islands, weigh several million tons, and rise several hundred feet above the sea surface. Cape Farewell is visible toward the bottom right of the view. Julianehab Bay and the Bredev fjord can be seen toward the center of the photograph. Godthab, the main settlement on Greenland, is barely visible to the north of the Frederikeshabs Icefield near the left center of the view.

Greenland as seen by the STS-66 shuttle Atlantis

NASA Image and Video Library

1994-11-14

This north-looking view of southwestern Greenland was taken in November, 1994, and shows numerous indentations, many of which contain small settlements. These fjords were carved by the glaciers of the last ice age 10,000 years ago. Even today, the ice in the center of Greenland is nearly 3,500 meters (11,000 feet) thick and great rivers of ice continuously flow down toward the sea, where they melt or break off as icebergs. Some Icebergs exceed the size of small islands, weigh several million tons, and rise several hundred feet above the sea surface. Cape Farewell is visible toward the bottom right of the view. Julianehab Bay and the Bredev fjord can be seen toward the center of the photograph. Godthab, the main settlement on Greenland, is barely visible to the north of the Frederikeshabs Icefield near the left center of the view.

Workshop on Radar Investigations of Planetary and Terrestrial Environments

NASA Technical Reports Server (NTRS)

2005-01-01

Contents include the following: Salt Kinematics and InSAR. SAR Interferometry as a Tool for Monitoring Coastal Changes in the Nile River Delta of Egypt. Modem Radar Techniques for Geophysical Applications: Two Examples. WISDOM Experiment on the EXOMARS ESA Mission. An Ice Thickness Study Utilizing Ground Penetrating Radar on the Lower Jamapa. Probing the Martian Subsurface with Synthetic Aperture Radar. Planetary Surface Properties from Radar Polarimetric Observations. Imaging the Sub-surface Reflectors : Results From the RANETA/NETLANDER Field Test on the Antarctic Ice Shelf. Strategy for Selection of Mars Geophysical Analogue Sites. Observations of Low Frequency Low Altitude Plasma Oscillations at Mars and Implications for Electromagnetic Sounding of the Subsurface. Ionospheric Transmission Losses Associated with Mars-orbiting Radar. A Polarimetric Scattering Model for the 2-Layer Problem. Radars for Imaging and Sounding of Polar Ice Sheets. Strata: Ground Penetrating Radar for Mars Rovers. Scattering Limits to Depth of Radar Investigation: Lessons from the Bishop Tuff.

Distribution and character of naleds in northeastern Alaska

USGS Publications Warehouse

Harden, Deborah; Barnes, Peter W.; Reimnitz, Erk

1977-01-01

An examination of the distribution of river naleds seen in Landsat satellite imagery and high- and low-altitude aerial photography of Alaska's North Slope indicates that these features are widespread east of the Colville River and less abundant to the west. Where naleds occur, stream channels are wide and often form braided channels. Their distribution can be related to changes in stream gradient and to the occurrence of springs. Large naleds, such as on the Kongakut River, often remain through the summer melt season to form the nucleus of icing in the succeeding winter. Major naleds also are likely to significantly influence the nature of permafrost in their immediate vicinity. The map of naleds may serve as a guide to the occurrence of year-round flowing water, a sparse commodity in northern Alaska.

Evolution of Early Pleistocene fluvial systems in central Poland prior to the first ice sheet advance - a case study from the Bełchatów lignite mine

NASA Astrophysics Data System (ADS)

Goździk, Jan; Zieliński, Tomasz

2017-06-01

Deposits formed between the Neogene/Pleistocene transition and into the Early Pleistocene have been studied, mainly on the basis of drillings and at rare, small outcrops in the lowland part of Polish territory. At the Bełchatów lignite mine (Kleszczów Graben, central Poland), one of the largest opencast pits in Europe, strata of this age have long been exposed in extensive outcrops. The present paper is based on our field studies and laboratory analyses, as well as on research data presented by other authors. For that reason, it can be seen as an overview of current knowledge of lowermost Pleistocene deposits at Bełchatów, where exploitation of the Quaternary overburden has just been completed. The results of cartographic work, sedimentological, mineralogical and palynological analyses as well as assessment of sand grain morphology have been considered. All of these studies have allowed the distinction of three Lower Pleistocene series, i.e., the Łękińsko, Faustynów and Krzaki series. These were laid down in fluvial environments between the end of the Pliocene up to the advance of the first Scandinavian ice sheet on central Poland. The following environmental features have been interpreted: phases of river incision and aggradation, changes of river channel patterns, source sediments for alluvia, rates of aeolian supply to rivers and roles of fluvial systems in morphological and geological development of the area. The two older series studied, i.e., Łękińsko and Faustynów, share common characteristics. They were formed by sinuous rivers in boreal forest and open forest environments. The Neogene substratum was the source of the alluvium. The younger series (Krzaki) formed mainly in a braided river setting, under conditions of progressive climatic cooling. Over time, a gradual increase of aeolian supply to the fluvial system can be noted; initially, silt and sand were laid down, followed by sand only during cold desert conditions. These fluvio-periglacial conditions are identified in the foreground of the advance of the oldest ice sheet into this part of central Poland. The series studied have been compared with other fluvial successions which accumulated in the Kleszczów Graben during subsequent glaciations so as to document general changes in fluvial systems as reactions to climatic evolution. Thus, a palaeoenvironmental scenario has emerged which could be considered to be characteristic of central Poland during the Early Pleistocene.

Climate and Cryosphere (CliC) Project and its Interest in Arctic Hydrology Research

NASA Astrophysics Data System (ADS)

Yang, D.; Prowse, T. D.; Steffen, K.; Ryabinin, V.

2009-12-01

The cryosphere is an important and dynamic component of the global climate system. The global cryosphere is changing rapidly, with changes in the Polar Regions receiving particular attention during the International Polar Year 2007-2008. The Climate and Cryosphere (CliC) Project is a core project of the World Climate Research Programme (WCRP) and is co-sponsored by WCRP, SCAR (Scientific Committee for Antarctic Research) and IASC (International Committee for Antarctic Research). The principal goal of CliC is to assess and quantify the impacts that climatic variability and change have on components of the cryosphere and the consequences of these impacts for the climate system. To achieve its objectives, CliC coordinates international and regional projects, partners with other organizations in joint initiatives, and organizes panels and working groups to lead and coordinate advanced research aimed at closing identified gaps in scientific knowledge about climate and cryosphere. The terrestrial cryosphere includes land areas where snow cover, lake- and river-ice, glaciers and ice caps, permafrost and seasonally frozen ground and solid precipitation occur. The main task of this theme is to improve estimates and quantify the uncertainty of water balance and related energy flux components in cold climate regions. This includes precipitation (both solid and liquid) distribution, properties of snow, snow melt, evapotranspiration, sublimation, water movement through frozen and unfrozen ground, water storage in watersheds, river- and lake-ice properties and processes, and river runoff. The focus of this theme includes two specific issues: the role of permafrost and frozen ground in the carbon balance, and precipitation in cold climates. Hydrological studies of cold regions will provide a key contribution to the new theme crosscut, which focuses on the cryospheric input to the freshwater balance of the Arctic. This presentation will provide an overview and update of recent developments of cold region hydrometeorology research activities and future challenges in arctic hydrology and climate change investigations.

Late Cenozoic surficial deposits and valley evolution of unglaciated northern New Jersey

USGS Publications Warehouse

Stanford, S.D.

1993-01-01

Multiple alluvial, colluvial, and eolian deposits in unglaciated northern New Jersey, and the eroded bedrock surfaces on which they rest, provide evidence of both long-term valley evolution driven by sustained eustatic baselevel lowering and short-term filling and excavation of valleys during glacial and interglacial climate cycles. The long-term changes occur over durations of 106 years, the short-term features evolve over durations of 104 to 105 years. Direct glacial effects, including blockage of valleys by glacial ice and sediment, and valley gradient reversals induced by crustal depression, are relatively sudden changes that account for several major Pleistocene drainage shifts. After deposition of the Beacon Hill fluvial gravel in the Late Miocene, lowering of sea level, perhaps in response to growth of the Antarctic ice sheet, led to almost complete dissection of the gravel. A suite of alluvial, colluvial, and eolian sediments was deposited in the dissected landscape. The fluvial Bridgeton Formation was deposited in the Raritan lowland, in the Amboy-Trenton lowland, and in the Delaware valley. Following southeastward diversion of the main Bridgeton river, perhaps during Late Pliocene or Early Pleistocene glaciation, northeastward drainage was established on the inactive Bridgeton fluvial plain. About 30 to 45 m of entrenchment followed, forming narrow, incised valleys within which Late Pleistocene deposits rest. This entrenchment may have occurred in response to lowered sea level caused by growth of ice sheets in the northern hemisphere. Under periglacial conditions in the Middle and Late Pleistocene, valleys were partially filled with alluvium and colluvium. During interglacials slopes were stabilized by vegetation and the alluvial and colluvial valley-fill was excavated by gullying, bank erosion, and spring sapping. During Illinoian and late Wisconsinan glaciation, the lower Raritan River was diverted when glacial deposits blocked its valley, and the Delaware River was partially diverted down the isostatically-steepened lower Millstone valley. ?? 1993.

Fluvial disturbance patches and cottonwood recruitment along the Upper Missouri River, Montana

USGS Publications Warehouse

Auble, G.T.; Scott, M.L.

1998-01-01

The disturbance patches most suitable for seedling establishment of pioneer riparian trees are also subject to future disturbances that produce high seedling mortality. We are monitoring plains cottonwood seedling establishment and mortality along the Wild and Scenic reach of the Missouri River upstream of Fort Peck Reservoir, Montana at four sites subject to livestock grazing and four paired, ungrazed exclosures. New seedlings at these sites were largely restricted to surfaces inundated by spring and summer flows. Winter ice drives and livestock grazing are important mortality factors along the study reach. Livestock grazing reduced seedling densities, although the position of these seedlings in normal flow years means it is unlikely that they will survive future disturbance. Average values of the maximum density parameter of a Gaussian curve of seedling distribution along a hydraulic gradient of inundating discharge were 30 and 114 seedlings/m2 on ungrazed sites in 1996 and 1997, compared to 19 and 18 seedlings/m2 for grazed sites. Water-surface elevations produced by ice drives and damming in the severe winter of 1995-1996 corresponded to inundating discharges of 1,670 to 4,580 m3/s. No existing trees at the study sites occurred at inundating discharges below 1,625 m3/s. Seedlings established as a result of maximum summer flows of 827 and 1,201 m3/s in 1996 and 1997 were all below the elevation of the 10-year return flow of 1,495 m3/s. Recruitment of plains cottonwood trees along this reach of the Missouri River is strongly dependent on infrequent high flows that position moist, bare disturbed patches high enough for seedlings to establish and survive subsequent flooding and ice scour, in contrast to other reaches and streams where hydrogeomophic processes of channel meandering and narrowing produce different patterns of disturbance patches.

Abrupt drainage cycles of the Fennoscandian Ice Sheet

PubMed Central

Soulet, Guillaume; Ménot, Guillemette; Bayon, Germain; Rostek, Frauke; Ponzevera, Emmanuel; Toucanne, Samuel; Lericolais, Gilles; Bard, Edouard

2013-01-01

Continental ice sheets are a key component of the Earth’s climate system, but their internal dynamics need to be further studied. Since the last deglaciation, the northern Eurasian Fennoscandian Ice Sheet (FIS) has been connected to the Black Sea (BS) watershed, making this basin a suitable location to investigate former ice-sheet dynamics. Here, from a core retrieved in the BS, we combine the use of neodymium isotopes, high-resolution elemental analysis, and biomarkers to trace changes in sediment provenance and river runoff. We reveal cyclic releases of meltwater originating from Lake Disna, a proglacial lake linked to the FIS during Heinrich Stadial 1. Regional interactions within the climate–lake–FIS system, linked to changes in the availability of subglacial water, led to abrupt drainage cycles of the FIS into the BS watershed. This phenomenon raised the BS water level by ∼100 m until the sill of the Bosphorus Strait was reached, flooding the vast northwestern BS shelf and deeply affecting the hydrology and circulation of the BS and, probably, of the Marmara and Aegean Seas. PMID:23569264

Abrupt drainage cycles of the Fennoscandian Ice Sheet.

PubMed

Soulet, Guillaume; Ménot, Guillemette; Bayon, Germain; Rostek, Frauke; Ponzevera, Emmanuel; Toucanne, Samuel; Lericolais, Gilles; Bard, Edouard

2013-04-23

Continental ice sheets are a key component of the Earth's climate system, but their internal dynamics need to be further studied. Since the last deglaciation, the northern Eurasian Fennoscandian Ice Sheet (FIS) has been connected to the Black Sea (BS) watershed, making this basin a suitable location to investigate former ice-sheet dynamics. Here, from a core retrieved in the BS, we combine the use of neodymium isotopes, high-resolution elemental analysis, and biomarkers to trace changes in sediment provenance and river runoff. We reveal cyclic releases of meltwater originating from Lake Disna, a proglacial lake linked to the FIS during Heinrich Stadial 1. Regional interactions within the climate-lake-FIS system, linked to changes in the availability of subglacial water, led to abrupt drainage cycles of the FIS into the BS watershed. This phenomenon raised the BS water level by ∼100 m until the sill of the Bosphorus Strait was reached, flooding the vast northwestern BS shelf and deeply affecting the hydrology and circulation of the BS and, probably, of the Marmara and Aegean Seas.

Glaciers along proposed routes extending the Copper River Highway, Alaska

USGS Publications Warehouse

Glass, R.L.

1996-01-01

Three inland highway routes are being considered by the Alaska Department of Transportation and Public Facilities to connect the community of Cordova in southcentral Alaska to a statewide road system. The routes use part of a Copper River and Northwest Railway alignment along the Copper River through mountainous terrain having numerous glaciers. An advance of any of several glaciers could block and destroy the roadway, whereas retreating glaciers expose large quantities of unconsolidated, unvegetated, and commonly ice-rich sediments. The purpose of this study was to map historical locations of glacier termini near these routes and to describe hazards associated with glaciers and seasonal snow. Historical and recent locations of glacier termini along the proposed Copper River Highway routes were determined by reviewing reports and maps and by interpreting aerial photographs. The termini of Childs, Grinnell, Tasnuna, and Woodworth Glaciers were 1 mile or less from a proposed route in the most recently available aerial photography (1978-91); the termini of Allen, Heney, and Schwan Glaciers were 1.5 miles or less from a proposed route. In general, since 1911, most glaciers have slowly retreated, but many glaciers have had occasional advances. Deserted Glacier and one of its tributary glaciers have surge-type medial moraines, indicating potential rapid advances. The terminus of Deserted Glacier was about 2.1 miles from a proposed route in 1978, but showed no evidence of surging. Snow and rock avalanches and snowdrifts are common along the proposed routes and will periodically obstruct the roadway. Floods from ice-dammed lakes also pose a threat. For example, Van Cleve Lake, adjacent to Miles Glacier, is as large as 4.4 square miles and empties about every 6 years. Floods from drainages of Van Cleve Lake have caused the Copper River to rise on the order of 20 feet at Million Dollar Bridge.

The Significance of Shifts in Precipitation Patterns: Modelling the Impacts of Climate Change and Glacier Retreat on Extreme Flood Events in Denali National Park, Alaska

PubMed Central

Crossman, Jill; Futter, Martyn N.; Whitehead, Paul G.

2013-01-01

In glacier-fed systems climate change may have various effects over a range of time scales, including increasing river discharge, flood frequency and magnitude. This study uses a combination of empirical monitoring and modelling to project the impacts of climate change on the glacial-fed Middle Fork Toklat River, Denali National Park, Alaska. We use a regional calibration of the model HBV to account for a paucity of long term observed flow data, validating a local application using glacial mass balance data and summer flow records. Two Global Climate Models (HADCM3 and CGCM2) and two IPCC scenarios (A2 and B2) are used to ascertain potential changes in meteorological conditions, river discharge, flood frequency and flood magnitude. Using remote sensing methods this study refines existing estimates of glacial recession rates, finding that since 2000, rates have increased from 24m per year to 68.5m per year, with associated increases in ablation zone ice loss. GCM projections indicate that over the 21st century these rates will increase still further, most extensively under the CGCM2 model, and A2 scenarios. Due to greater winter precipitation and ice and snow accumulation, glaciers release increasing meltwater quantities throughout the 21st century. Despite increases in glacial melt, results indicate that it is predominantly precipitation that affects river discharge. Three of the four IPCC scenarios project increases in flood frequency and magnitude, events which were primarily associated with changing precipitation patterns, rather than extreme temperature increases or meltwater release. Results suggest that although increasing temperatures will significantly increase glacial melt and winter baseflow, meltwater alone does not pose a significant flood hazard to the Toklat River catchment. Projected changes in precipitation are the primary concern, both through changing snow volumes available for melt, and more directly through increasing catchment runoff. PMID:24023925

Migration depths of juvenile Chinook salmon and steelhead relative to total dissolved gas supersaturation in a Columbia River reservoir

USGS Publications Warehouse

Beeman, J.W.; Maule, A.G.

2006-01-01

The in situ depths of juvenile salmonids Oncorhynchus spp. were studied to determine whether hydrostatic compensation was sufficient to protect them from gas bubble disease (GBD) during exposure to total dissolved gas (TDG) supersaturation from a regional program of spill at dams meant to improve salmonid passage survival. Yearling Chinook salmon O. tshawytscha and juvenile steelhead O. mykiss implanted with pressure-sensing radio transmitters were monitored from boats while they were migrating between the tailrace of Ice Harbor Dam on the Snake River and the forebay of McNary Dam on the Columbia River during 1997-1999. The TDG generally decreased with distance from the tailrace of the dam and was within levels known to cause GBD signs and mortality in laboratory bioassays. Results of repeated-measures analysis of variance indicated that the mean depths of juvenile steelhead were similar throughout the study area, ranging from 2.0 m in the Snake River to 2.3 m near the McNary Dam forebay. The mean depths of yearling Chinook salmon generally increased with distance from Ice Harbor Dam, ranging from 1.5 m in the Snake River to 3.2 m near the forebay. Juvenile steelhead were deeper at night than during the day, and yearling Chinook salmon were deeper during the day than at night. The TDG level was a significant covariate in models of the migration depth and rates of each species, but no effect of fish size was detected. Hydrostatic compensation, along with short exposure times in the area of greatest TDG, reduced the effects of TDG exposure below those generally shown to elicit GBD signs or mortality. Based on these factors, our results indicate that the TDG limits of the regional spill program were safe for these juvenile salmonids.

The significance of shifts in precipitation patterns: modelling the impacts of climate change and glacier retreat on extreme flood events in Denali National Park, Alaska.

PubMed

Crossman, Jill; Futter, Martyn N; Whitehead, Paul G

2013-01-01

In glacier-fed systems climate change may have various effects over a range of time scales, including increasing river discharge, flood frequency and magnitude. This study uses a combination of empirical monitoring and modelling to project the impacts of climate change on the glacial-fed Middle Fork Toklat River, Denali National Park, Alaska. We use a regional calibration of the model HBV to account for a paucity of long term observed flow data, validating a local application using glacial mass balance data and summer flow records. Two Global Climate Models (HADCM3 and CGCM2) and two IPCC scenarios (A2 and B2) are used to ascertain potential changes in meteorological conditions, river discharge, flood frequency and flood magnitude. Using remote sensing methods this study refines existing estimates of glacial recession rates, finding that since 2000, rates have increased from 24 m per year to 68.5m per year, with associated increases in ablation zone ice loss. GCM projections indicate that over the 21(st) century these rates will increase still further, most extensively under the CGCM2 model, and A2 scenarios. Due to greater winter precipitation and ice and snow accumulation, glaciers release increasing meltwater quantities throughout the 21(st) century. Despite increases in glacial melt, results indicate that it is predominantly precipitation that affects river discharge. Three of the four IPCC scenarios project increases in flood frequency and magnitude, events which were primarily associated with changing precipitation patterns, rather than extreme temperature increases or meltwater release. Results suggest that although increasing temperatures will significantly increase glacial melt and winter baseflow, meltwater alone does not pose a significant flood hazard to the Toklat River catchment. Projected changes in precipitation are the primary concern, both through changing snow volumes available for melt, and more directly through increasing catchment runoff.

Enzymatic regulation of organic matter metabolism in Siberia's Kolyma River Watershed

NASA Astrophysics Data System (ADS)

Mann, P. J.; Sobczak, W.; Vonk, J. E.; Davydova, A.; Schade, J.; Bulygina, E.; Davydov, S.; Zimov, N.; Holmes, R. M.

2012-04-01

Arctic soils contain vast amounts of ancient organic carbon stored in permafrost that can be unlocked and remobilised via permafrost thaw and bacterial degradation. The mechanisms regulating the release and fate of this carbon are important to understand if we wish to predict future changes in the global carbon cycle. Microbial communities release enzymes into the environment (ectoenzymes) as a means of degrading organic matter and to acquire carbon, nitrogen and phosphorus for assimilation. We measured potential activities of a suite of ectoenzymes within surface waters collected from a range of streams and rivers throughout the Kolyma River basin, Siberia. Ectoenzyme activities were additionally measured in Kolyma river waters collected at three distinct periods of the hydrograph (under-ice, freshet and summer conditions). Seven enzymes were studied allowing bacterial requirements for a wide range of compounds including lignin, carbohydrates, proteins and cellulose to be assessed. Concurrent measurements of DOC lability were conducted using biological oxygen demand assays conducted over 5 days (BOD). Phenol oxidase activity was found to strongly correlate to BOD (r2=0.68) and stream CO2 concentration (r2=0.76) across all of the study sites, suggesting the rate of phenolic degradation may be a controlling factor in organic carbon metabolism. The activity rate in ectoenzymes that catalyze phosphate, lignin and carbon substrates varied significantly within the Kolyma river over the hydrograph, suggesting that seasonal changes in organic matter composition may also shift the limiting resource for bacterial degradation. Extremely high activity rates in ectoenzymes that catalyze lignin, chitin, cellulose and proteins were measured in waters draining permafrost ice complexes. It is apparent that organic carbon is continually processed throughout the stream network, and that its ultimate fate is linked to organic matter composition. We demonstrate that organic carbon derived from ancient permafrost thaw may be highly biolabile within Arctic aquatic ecosystems.

Hydrogeology of the West Branch Delaware River basin, Delaware County, New York

USGS Publications Warehouse

Reynolds, Richard J.

2013-01-01

In 2009, the U.S. Geological Survey, in cooperation with the New York State Department of Environmental Conservation, began a study of the hydrogeology of the West Branch Delaware River (Cannonsville Reservoir) watershed. There has been recent interest by energy companies in developing the natural gas reserves that are trapped within the Marcellus Shale, which is part of the Hamilton Group of Devonian age that underlies all the West Branch Delaware River Basin. Knowing the extent and thickness of stratified-drift (sand and gravel) aquifers within this basin can help State and Federal regulatory agencies evaluate any effects on these aquifers that gas-well drilling might produce. This report describes the hydrogeology of the 455-square-mile basin in the southwestern Catskill Mountain region of southeastern New York and includes a detailed surficial geologic map of the basin. Analysis of surficial geologic data indicates that the most widespread surficial geologic unit within the basin is till, which is present as deposits of ablation till in major stream valleys and as thick deposits of lodgment till that fill upland basins. Till and colluvium (remobilized till) cover about 89 percent of the West Branch Delaware River Basin, whereas stratified drift (outwash and ice-contact deposits) and alluvium account for 8.9 percent. The Cannonsville Reservoir occupies about 1.9 percent of the basin area. Large areas of outwash and ice-contact deposits occupy the West Branch Delaware River valley along its entire length. These deposits form a stratified-drift aquifer that ranges in thickness from 40 to 50 feet (ft) in the upper West Branch Delaware River valley, from 70 to 140 ft in the middle West Branch Delaware River valley, and from 60 to 70 ft in the lower West Branch Delaware River valley. The gas-bearing Marcellus Shale underlies the entire West Branch Delaware River Basin and ranges in thickness from 600 to 650 ft along the northern divide of the basin to 750 ft thick along the southern divide. The depth to the top of the Marcellus Shale ranges from 3,240 ft along the northern basin divide to 4,150 ft along the southern basin divide. Yields of wells completed in the aquifer are as high as 500 gallons per minute (gal/min). Springs from fractured sandstone bedrock are an important source of domestic and small municipal water supplies in the West Branch Delaware River Basin and elsewhere in Delaware County. The average yield of 178 springs in Delaware County is 8.5 gal/min with a median yield of 3 gal/min. An analysis of two low-flow statistics indicates that groundwater contributions from fractured bedrock compose a significant part of the base flow of the West Branch Delaware River and its tributaries.

Evolving hydrologic connectivity in discontinuous permafrost lowlands: what it means for lake systems

NASA Astrophysics Data System (ADS)

Walvoord, M. A.; Jepsen, S. M.; Rover, J.; Voss, C. I.; Briggs, M. A.

2015-12-01

Permafrost influence on the hydrologic connectivity of surface water bodies in high-latitude lowlands is complicated by subsurface heterogeneity and the propensity of the system to change over time. In general, permafrost limits the subsurface exchange of water, solute, and nutrients between lakes and rivers. It follows that permafrost thaw could enhance subsurface hydrologic connectivity among surface water bodies, but the impact of this process on lake distribution is not well known. Changes in the extent of lakes in interior Alaska have important ecological and societal impacts since lakes provide (1) critical habitat for migratory arctic shorebirds and waterfowl, fish, and wildlife, and (2) provisional, recreational, and cultural resources for local communities. We utilize electromagnetic imaging of the shallow subsurface and remote sensing of lake level dynamics in the Yukon Flats of interior Alaska, USA, together with water balance modeling, to gain insight into the influence of discontinuous permafrost on lowland lake systems. In the study region with relatively low precipitation, observations suggest that lakes that are hydrologically isolated during normal conditions are sustained by periodic river flooding events, including ice-jam floods that occur during river ice break-up. Climatically-influenced alterations in flooding frequency and intensity, as well as depth to permafrost, are quantitatively assessed in the context of lake maintenance. Scenario modeling is used to evaluate lake level evolution under plausible changing conditions. Model results demonstrate how permafrost degradation can reduce the dependence of typical lowland lakes on flooding events. Study results also suggest that river flooding may recharge a more spatially widespread zone of lakes and wetlands under future scenarios of permafrost table deepening and enhanced subsurface hydrologic connectivity.

Atmospheric Circulation Patterns over East Asia and Their Connection with Summer Precipitation and Surface Air Temperature in Eastern China during 1961-2013

NASA Astrophysics Data System (ADS)

Li, Shuping; Hou, Wei; Feng, Guolin

2018-04-01

Based on the NCEP/NCAR reanalysis data and Chinese observational data during 1961-2013, atmospheric circulation patterns over East Asia in summer and their connection with precipitation and surface air temperature in eastern China as well as associated external forcing are investigated. Three patterns of the atmospheric circulation are identified, all with quasi-barotropic structures: (1) the East Asia/Pacific (EAP) pattern, (2) the Baikal Lake/Okhotsk Sea (BLOS) pattern, and (3) the eastern China/northern Okhotsk Sea (ECNOS) pattern. The positive EAP pattern significantly increases precipitation over the Yangtze River valley and favors cooling north of the Yangtze River and warming south of the Yangtze River in summer. The warm sea surface temperature anomalies over the tropical Indian Ocean suppress convection over the northwestern subtropical Pacific through the Ekman divergence induced by a Kelvin wave and excite the EAP pattern. The positive BLOS pattern is associated with below-average precipitation south of the Yangtze River and robust cooling over northeastern China. This pattern is triggered by anomalous spring sea ice concentration in the northern Barents Sea. The anomalous sea ice concentration contributes to a Rossby wave activity flux originating from the Greenland Sea, which propagates eastward to North Pacific. The positive ECNOS pattern leads to below-average precipitation and significant warming over northeastern China in summer. The reduced soil moisture associated with the earlier spring snowmelt enhances surface warming over Mongolia and northeastern China and the later spring snowmelt leads to surface cooling over Far East in summer, both of which are responsible for the formation of the ECNOS pattern.

Susitna Glacier, Alaska

NASA Image and Video Library

2017-12-08

NASA image acquired August 27, 2009 Like rivers of liquid water, glaciers flow downhill, with tributaries joining to form larger rivers. But where water rushes, ice crawls. As a result, glaciers gather dust and dirt, and bear long-lasting evidence of past movements. Alaska’s Susitna Glacier revealed some of its long, grinding journey when the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite passed overhead on August 27, 2009. This satellite image combines infrared, red, and green wavelengths to form a false-color image. Vegetation is red and the glacier’s surface is marbled with dirt-free blue ice and dirt-coated brown ice. Infusions of relatively clean ice push in from tributaries in the north. The glacier surface appears especially complex near the center of the image, where a tributary has pushed the ice in the main glacier slightly southward. A photograph taken by researchers from the U.S. Geological Survey (archived by the National Snow and Ice Data Center) shows an equally complicated Susitna Glacier in 1970, with dirt-free and dirt-encrusted surfaces forming stripes, curves, and U-turns. Susitna flows over a seismically active area. In fact, a 7.9-magnitude quake struck the region in November 2002, along a previously unknown fault. Geologists surmised that earthquakes had created the steep cliffs and slopes in the glacier surface, but in fact most of the jumble is the result of surges in tributary glaciers. Glacier surges—typically short-lived events where a glacier moves many times its normal rate—can occur when melt water accumulates at the base and lubricates the flow. This water may be supplied by meltwater lakes that accumulate on top of the glacier; some are visible in the lower left corner of this image. The underlying bedrock can also contribute to glacier surges, with soft, easily deformed rock leading to more frequent surges. NASA Earth Observatory image created by Jesse Allen and Robert Simmon, using data provided courtesy of NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. Caption by Michon Scott. Instrument: Terra - ASTER Credit: NASA Earth Observatory NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook

A Hot Knife Through Ice-Cream: Earthflow Response to Channel Incision (Or Channel Response to Earthflows?), Eel River Canyon, California

NASA Astrophysics Data System (ADS)

Mackey, B. H.; Roering, J. J.; McKean, J. A.

2007-12-01

Abundant glacier-like earthflow features are recognized as a primary erosional process in the highly erodable Franciscan Melange of the Eel River Basin, CA. Despite their prominence in this "melting ice-cream" topography, many questions regarding their effects on the long term sediment flux from this rapidly eroding basin remain unresolved. For example, does an earthflow's basal shear zone propagate vertically downwards with vertical river incision? What controls the upslope and lateral extent of individual earthflows? How does the erosive power of a river influence the rate of earthflow movement, or conversely do earthflow toe deposits regulate the rate of river incision? Here we present preliminary findings derived from study of 200km2 of lidar data (1m resolution) covering hillslopes adjacent to 30km of the Eel River. Lidar allows detailed analysis of the interaction between earthflows and the drainage network, and we document how inferred changes in local base level are propagated throughout adjacent hillslopes via earthflow movement. The most active earthflows (determined by field surveying and analysis of aerial photos rectified using lidar- generated digital topography) coincide with locally steep sections of channel, while downstream of the most active flows we frequently observe less-active or dormant earthflows. This observation supports the idea that the locations of the most active earthflows coincide with headward propagating knickpoints in the channel. The rate of earthflow movement appears to slow when an earthflow exhausts the upslope area of easily mobilized sediment. Earthflow toes can protrude directly into the channel, causing the channel to narrow and steepen, and even undercut the opposite bank. Large resistant boulders (>2m diameter) transported by the earthflow accumulate in the streambed and appear to both act as a check on further channel incision and earthflow movement. In contrast, areas adjacent to active earthflows exhibit smooth hillslopes, which show little or no evidence for recent instability. Such unfailed hillslopes preferentially occur near ridges or adjacent to strath terraces, and appear to be largely isolated from the effects of channel incision.

Ice core evidence of rapid air temperature increases since 1960 in alpine areas of the Wind River Range, Wyoming, United States

USGS Publications Warehouse

Naftz, D.L.; Susong, D.D.; Schuster, P.F.; Cecil, L.D.; Dettinger, M.D.; Michel, R.L.; Kendall, C.

2002-01-01

Site-specific transfer functions relating delta oxygen 18 (δ18O) values in snow to the average air temperature (TA) during storms on Upper Fremont Glacier (UFG) were used in conjunction with δ18O records from UFG ice cores to reconstruct long-term trends in air temperature from alpine areas in the Wind River Range, Wyoming. Transfer functions were determined by using data collected from four seasonal snowpacks (1989-1990, 1997-1998, 1998-1999, and 1999-2000). The timing and amount of each storm was determined from an automated snowpack telemetry (SNOTEL) site, 22 km northeast of UFG, and ~1060 m in elevation below UFG. Statistically significant and positive correlations between δ18O values in the snow and TA were consistently found in three of the four seasonal snowpacks. The snowpack with the poor correlation was deposited in 1997-1998 during the 1997-1998 El Nino Southern Oscillation (ENSO). An ultrasonic snow-depth sensor installed on UFG provided valuable insights into site-specific storms and postdepositional processes that occur on UFG. The timing of storms recorded at the UFG and Cold Springs SNOTEL sites were similar; however, selected storms did not correlate. Snow from storms occurring after mid-October and followed by high winds was most susceptible to redeposition of snow. This removal of lower temperature snowfall could potentially bias the δ18O values preserved in ice core records to environmental conditions reflecting higher air temperatures and lower wind speeds. Transfer functions derived from seasonal snow cover on UFG were used to reconstruct TA values from δ18O values determined from two ice cores collected from UFG. Reconstructed air temperatures from the ice core data indicate an increase in TA of ~3.5oC from the mid-1960s to the early 1990s in the alpine areas of northwestern Wyoming. Reconstructed TA from the ice core records between the end of the Little Ice Age (LIA), mid-1800s, and the early 1990s indicate a TA increase of ~55oC. The historically reconstructed TA values from the UFG were significantly higher than the global average observed during the 20th Century but were in agreement with TA increases observed at selected, high-altitude and high-latitude sites in other parts of the world. Additional research is required to determine if part of the observed trend toward heavier δ18O values in ice from the UFG since the LIA (and increased TA) is due to an increased proportion of snowfall from southerly storm tracks and moisture sources, as seems to have been the situation in 1997-1998. Copyright 2002 by the American Geophysical Union.

Identification of bomb-produced chlorine-36 in mid-latitude glacial ice of North America

USGS Publications Warehouse

DeWayne, Cecil L.; Vogt, S.

1997-01-01

In 1991, the U.S. Geological Survey collected a 160-meter (m) ice core from the Upper Fremont Glacier (43??07???N, 109??36???W) in the Wind River Mountain Range of Wyoming in the western United States [1]. In 1994-95, ice from this core was processed at the National Ice Core Laboratory in Denver, Colorado, and analyzed for chlorine-36 (36Cl) by accelerator mass spectrometry at PRIME Laboratory, Purdue University. A tritium bomb peak identified in the work by [1] was used as a marker to estimate the depth of bomb-produced 36Cl. Tritium concentrations ranged from 0 tritium units (TU) for older ice to more than 300 TU at 29 m below the surface of the glacier, a depth that includes ice that was deposited as snow during nuclear-weapons tests through the early 1960's. Maximum 36Cl production during nuclear-weapons tests was in the late 1950's; therefore, the analyses were performed on ice from a depth of 29.8 to 32 m. Calculated flux for 36Cl in ice deposited in the late 1950's ranged from 1.2 ?? 0.1 ?? 10-1 atoms/cm2 s for ice from 29.8 to 30.4 m, to 2.9 ?? 0.1 ?? 10-1 atoms/cm2 s for ice from 31.5 to 32.0 m. Ice samples from a depth of 104.7 to 106.3 m were selected to represent pre-weapons tests 36Cl flux. Calculated flux for 36Cl in this deeper ice was 4.6 ?? 0.8 ?? 10-3 atoms/cm2 s for ice from 104.7 to 105.5 m and 2.0 ?? 0.2 ?? 10-2 atoms/cm2 s for ice from 105.5 to 106.3 m. These flux calculations from the Upper Fremont Glacier analyses are the first for bomb-produced 36Cl in ice from a mid-latitude glacier in North America. It may now be possible to fully quantify the flux of 36Cl from nuclear-weapons tests archived in mid-latitude glacial ice and to gain a better understanding of the distribution of 36Cl and other cosmogenic nuclides.

Fossil organic matter characteristics in permafrost deposits of the northeast Siberian Arctic

Treesearch

Lutz Schirrmeister; Guido Grosse; Sebastian Wetterich; Pier Paul Overduin; Jens Straub; Edward A.G. Schuur; Hans-Wolfgang Hubberton

2011-01-01

Permafrost deposits constitute a large organic carbon pool highly vulnerable to degradation and potential carbon release due to global warming. Permafrost sections along coastal and river bank exposures in NE Siberia were studied for organic matter (OM) characteristics and ice content. OM stored in Quaternary permafrost grew, accumulated, froze, partly decomposed, and...

3. View of the northern twothirds of the dam showing ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. View of the northern two-thirds of the dam showing the Finch, Pruyn & Company intake structure and forebay canal on the right and the ice-covered log chute along the dam. Facing south-southwest. - Glens Falls Dam, 100' to 450' West of U.S. Route 9 Bridge Spanning Hudson River, Glens Falls, Warren County, NY

Mount Baker lahars and debris flows, ancient, modern, and future

USGS Publications Warehouse

Tucker, David S; Scott, Kevin M.; Grossman, Eric E.; Linneman, Scott

2014-01-01

Holocene lahars and large debris flows (>106 m3) have left recognizable deposits in the Middle Fork Nooksack valley. A debris flow in 2013 resulting from a landslide in a Little Ice Age moraine had an estimated volume of 100,000 m3, yet affected turbidity for the entire length of the river, and produced a slug of sediment that is currently being reworked and remobilized in the river system. Deposits of smaller-volume debris flows, deposited as terraces in the upper valley, may be entirely eroded within a few years. Consequently, the geologic record of small debris flows such as those that occurred in 2013 is probably very fragmentary. Small debris flows may still have significant impacts on hydrology, biology, and human uses of rivers downstream. Impacts include the addition of waves of fine sediment to stream loads, scouring or burying salmon-spawning gravels, forcing unplanned and sudden closure of municipal water intakes, damaging or destroying trail crossings, extending river deltas into estuaries, and adding to silting of harbors near river mouths.

Flood-plain areas of the Mississippi River, mile 866.8 to mile 888.0, Minnesota

USGS Publications Warehouse

Carlson, George H.; Gue, Lowell C.

1980-01-01

Profiles of the regional flood, 500-year flood, and flood-protection elevation have been developed for a 21-mile reach of the Mississippi River. Areas flooded by the regional flood and by the 500-year flood were delineated by photogrammetric mapping techniques and are shown on seven large-scale map sheets. Over 1,300 acres of flood plain are included in the cities of Anoka, Champlin, Coon Rapids, Dayton, Ramsey and Elk River, and in unincorporated areas of Wright County. The flood-outline maps and flood profiles comprise data needed by local units of government to adopt, enforce, and administer flood-plain management regulations along the Mississippi River throughout the study reach. Streamflow data from two gaging stations provided the basis for definition of the regional and 500-year floods. Cross-section data obtained at 83 locations were used to develop a digital computer model of the river. Flood elevation and discharge data from the 1965 flood provided a basis for adjusting the computer model. Information relating the history of floods, formation of ice jams, and duration of flood elevations at Anoka and at Elk River are included.

Water quality of selected rivers in the New England Coastal Basins in Maine, Massachusetts, New Hampshire, and Rhode Island, 1998-2000

USGS Publications Warehouse

Campo, Kimberly W.; Flanagan, Sarah M.; Robinson, Keith W.

2003-01-01

Nine rivers were monitored routinely for a variety of field conditions, dissolved ions, and nutrients during 1998-2000 as part of the New England Coastal Basins (NECB) study of the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program. The nine rivers, located primarily in the Boston metropolitan area, represented a gradient of increasing urbanization from 1 to 68 percent urban land use. Additional water samples were collected and analyzed for pesticides and volatile organic compounds at two of the nine rivers. Specific conductance data from all rivers were correlated with urban land use; specific conductance values increased during winter at some sites indicating the effect of road de-icing applications. In the more intensely urbanized basins, concentrations of sodium and chloride were high during winter and likely are attributed to road de-icing applications. Concentrations of total nitrogen and the various inorganic and organic nitrogen species were correlated with the percentage of urban land in the drainage basin. Total phosphorus concentrations also were correlated with urbanization in the drainage basin, but only for rivers draining less than 50 square miles. Preliminary U.S. Environmental Protection Agency total nitrogen and total phosphorus criteria for the rivers in the area were frequently exceeded at many of the rivers sampled. At the two sites monitored for pesticides and volatile organic compounds, the Aberjona and Charles Rivers near Boston, greater detection frequencies of pesticides were in samples from the spring and summer when pesticide usage was greatest. At both sites, herbicides were detected more commonly than insecticides. The herbicides prometon and atrazine and the insecticide diazinon were detected in over 50 percent of all samples collected from both rivers. No water samples contained pesticide concentrations exceeding any U.S. Environmental Protection Agency drinking-water standard or criteria for protecting freshwater aquatic life. The volatile organic compounds trichloroethylene, tetrachloroethylene, and cis-1,2- dichloroethylene--all solvents and de-greasers--were detected in all water samples from both rivers. The gasoline oxygenate methyl tert-butyl ether (MTBE) and the disinfection by-product chloroform were detected in all but one water sample from the two rivers. Two water samples from the Charles River had trichloroethylene concentrations that exceeded the U.S. Environmental Protection Agency Maximum Contaminant Level of 5 micrograms per liter for drinking water. Selected water-quality data from two NCEB rivers in the Boston metropolitan area were compared to two similarly sized intensely urban rivers in another NAWQA study area in the New York City metropolitan area and to other urban rivers sampled as part of the NAWQA Program nationally. Nutrient total nitrogen and total phosphorus concentrations and yields were less in the NECB study area than in the other study areas. In addition, the pesticides atrazine, carbaryl, diazinon, and prometon were detected less frequently and at lower concentrations in the two NECB rivers than in the New York City area streams or in the other urban NAWQA streams. Concentrations of the insecticides diazinon and carbaryl were detected more frequently and at higher concentrations in the NECB study area than in the other urban rivers sampled by NAWQA nationally. Detection frequency and concentrations of volatile organic compounds generally were higher in the two NECB streams than in the New York City area streams or in other urban NAWQA streams.

Modelling The Energy And Mass Balance Of A Black Glacier

NASA Astrophysics Data System (ADS)

Grossi, G.; Taschner, S.; Ranzi, R.

A distributed energy balance hydrologic model has been implemented to simulate the melting season of the Belvedere glacier, situated in the Anza river basin (North- Western Italy) for a few years. The Belvedere Glacier is an example of SblackS glacier, ´ since the ablation zone is covered by a significant debris layer. The glacierSs termi- nus has an altitude of 1785 m asl which is very unusual for the Southern side of the European Alps. The model accounts for the energy exchange processes at the inter- face between the atmospheric boundary layer and the snow/ice/debris layer. To run the model hydrometeorological and physiographic data were collected, including the depth of the debris cover and the tritium (3H) concentration in the glacial river. Mea- surements of the soil thermal conductivity were carried out during a field campaign organised within the glaciers monitoring GLIMS project, at the time of the passage of the Landsat and the Terra satellites last 15 August 2001. A comparison of the different energy terms simulated by the model assigns a dominant role to the shortwave radia- tion, which provides the highest positive contribution to the energy available for snow- and ice-melt, while the sensible heat turns out to be the second major source of heat. Longwave radiation balance and latent heat seem to be less relevant and often nega- tive. The role of the debris cover is not negligible, since its thermal insulation causes, on average, a decrease in the ice melt volume. One of the model variables is the tem- perature of the debris cover, which can be a useful information when a black glacier is to be monitored through remote sensing techniques. The visible and near infrared radi- ation data do not always provide sufficient information to detect the glaciers' margins beneath the debris layer. For this reason the information of the different thermal sur- face characteristics (pure ice, debris covered ice, rock), proved by the energy balance model results was applied for the glacierSs classification with a Landsat-TM image. Taking into account also the thermal infrared band leads to an improved classification result.

Diazotroph Diversity in the Sea Ice, Melt Ponds, and Surface Waters of the Eurasian Basin of the Central Arctic Ocean.

PubMed

Fernández-Méndez, Mar; Turk-Kubo, Kendra A; Buttigieg, Pier L; Rapp, Josephine Z; Krumpen, Thomas; Zehr, Jonathan P; Boetius, Antje

2016-01-01

The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing toward a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77°N. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed.

Diazotroph Diversity in the Sea Ice, Melt Ponds, and Surface Waters of the Eurasian Basin of the Central Arctic Ocean

PubMed Central

Fernández-Méndez, Mar; Turk-Kubo, Kendra A.; Buttigieg, Pier L.; Rapp, Josephine Z.; Krumpen, Thomas; Zehr, Jonathan P.; Boetius, Antje

2016-01-01

The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing toward a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77°N. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed. PMID:27933047

Organic Carbon Deposits of Soils Overlying the Ice Complex in the Lena River Delta

NASA Astrophysics Data System (ADS)

Zubrzycki, Sebastian; Pfeiffer, Eva-Maria; Kutzbach, Lars; Desiatkin, Aleksei

2017-04-01

The Lena River Delta (LRD) is located in northeast Siberia and extends over a soil covered area of around 21,500 km2. LRD likely stores more than half of the entire soil organic carbon (SOC) mass stored in deltas affected by permafrost. LRD consists of several geomorphic units. Recent studies showed that the spatially dominating Holocene units of the LRD (61 % of the area) store around 240 Tg of SOC and 12 Tg of nitrogen (N) within the first meter of ground. These units are a river terrace dominated by wet sedge polygons and the active floodplains. About 50 % of these reported storages are located in the perennially frozen ground below 50 cm depth and are excluded from intense biogeochemical exchange with the atmosphere today. However, these storages are likely to be mineralized in near future due to the projected temperature increases in this region. A substantial part of the LRD (1,712 km2) belongs to the so-called Ice Complex (Yedoma) Region, which formed during the Late Pleistocene. This oldest unit of the LRD is characterized by extensive plains incised by thermo-erosional valleys and large thermokarst depressions. Such depressions are called Alases and cover around 20 % of the area. Ice Complex deposits in the LDR are known to store high amounts of SOC. However, within the LRD no detailed spatial studies on SOC and N in the soils overlying Ice Complex and thermokarst depressions were carried out so far. We present here our "investigation in progress" on soils in these landscape units of the LRD. Our first estimates, based on 69 pedons sampled in 2008, show that the mean SOC stocks for the upper 30 cm of soils on both units were estimated at 13.0 kg m2 ± 4.8 kg m2 on the Ice Complex surfaces and at 13.1 kg m2 ± 3.8 kg m2 in the Alases. The stocks of N were estimated at 0.69 kg m2 ± 0.25 kg m2 and at 0.70 kg m2 ± 0.18 kg m2 on the Ice Complex surfaces and in the Alases, respectively. The estimated SOC and N pools for the depth of 30 cm within the investigated part of the LRD add to 20.9 Tg and 1.1 Tg, respectively. The Ice Complex surfaces (1,313 km2) store 17.1 ± 6.3 Tg SOC and 0.9 ± 0.3 Tg N, whereas the Alases (287 km2) store 3.8 ± 1.1 Tg SOC and 0.2 ± 0.05 Tg N within the investigated depth of 30 cm. Further analyses of the soil core material collected in 2015 will provide SOC and N pool estimates for a depth of 100 cm including both, the seasonally active layer and the perennially frozen ground. With continuing advanced analyses of an available digital elevation model, slopes will be designated with their extents and inclinations since the planar extents of slopes derived from satellite imagery do not correspond to the actual slope soil surface area, which is vital for spatial SOC and N storage calculations as well as trace gas release estimates. The actual soil surface area of slopes will be calculated prior to result extrapolations.

Ice Wedges as Winter Climate Archives - New Results from the Northeast Siberian Arctic and Discussion of the Paleoclimatic Value of Ice Wedges

NASA Astrophysics Data System (ADS)

Opel, T.; Meyer, H.; Laepple, T.; Rehfeld, K.; Mollenhauer, G.; Alexander, D.; Murton, J.

2017-12-01

Arctic climate has experienced major changes over the past millennia that are yet not fully understood in terms of external and internal controls, spatial, temporal, and seasonal patterns. The interpretation of stable isotope data in permafrost ice wedges provides unique information on past winter climate, not or not sufficiently captured by other Arctic climate archives. Ice wedges grow in polygonal patterns owing to frost cracking of the frozen ground in winter and frost-crack filling mostly by snowmelt in spring. Their oxygen isotope values are indicative of temperatures in the cold period of the year (meteorological winter and spring). Recently, an ice-wedge record from the Lena River Delta suggested for the first time, that Siberian winter temperatures were warming throughout the Holocene, contradicting most other Arctic paleoclimate reconstructions. As this was based on a single record, the representativity and spatial extent of the reconstructed winter warming signal remained unclear. In this two-part contribution, we first present a new ice-wedge δ18O record from the Oyogos Yar mainland coast (Northeast Siberian Arctic) and then discuss more generally the paleoclimatic value of ice wedges. The new Oyogos Yar ice-wedge record is based on paired stable-isotope and radiocarbon-age data and spans the last two millennia. It confirms the long-term winter warming signal as well as the unprecedented temperature rise in the last decades. This demonstrates that winter warming over the last millennia is a coherent feature in the Northeastern Siberian Arctic, supporting the hypothesis of an insolation-driven seasonal Holocene temperature evolution followed by a strong warming most likely related to anthropogenic forcing. Considering additional ice-wedge data from the Siberian Laptev Sea region we discuss the paleoclimatic value of ice wedges as high-quality winter climate archive. We assess potentials and challenges of this so far rather understudied source of paleoclimate information that remains to be evaluated systematically. In addition, we outline priorities for future ice-wedge research in order to fully exploit the potential of ice wedges for paleoclimate reconstruction, including e.g. better process understanding, dating, and data-model comparison.

Water-quality trends in New England rivers during the 20th century

USGS Publications Warehouse

Robinson, Keith W.; Campbell, Jean P.; Jaworski, Norbert A.

2003-01-01

Water-quality data from the Merrimack, Blackstone, and Connecticut Rivers in New England during parts of the 20th century were examined for trends in concentrations of sulfate, chloride, residue upon evaporation, nitrate, and total phosphorus. The concentrations of all five of these constituents show statistically significant trends during the century. Annual concentrations of sulfate and total phosphorus decreased during the second half of the century, whereas annual concentrations of nitrate, chloride, and residues increased throughout the century. In the Merrimack River, annual chloride concentrations increased by an order of magnitude. Annual nitrate concentrations also increased by an order of magnitude in the Merrimack and Connecticut Rivers. These changes in the water quality probably are related to changing human activities. Most notable is the relation between increasing use of road de-icing salts and chloride concentrations in rivers. In addition, changes in concentrations of nitrate and phosphorus probably are related to agricultural use of nitrogen and phosphorus fertilizers. For all the water-quality constituents assessed, concentrations were greatest in the Blackstone River. The Blackstone River Basin is smaller and more highly urbanized than the other basins studied. Data-collection programs that span multiple decades can provide valuable insight on the effects of changing human population and societal activities on the water quality of rivers. This study was done as part of the U.S. Geological Survey's National Water-Quality Assessment Program.

Supporting inland waterway transport on German waterways by operational forecasting services - water-levels, discharges, river ice

NASA Astrophysics Data System (ADS)

Meißner, Dennis; Klein, Bastian; Ionita, Monica; Hemri, Stephan; Rademacher, Silke

2017-04-01

Inland waterway transport (IWT) is an important commercial sector significantly vulnerable to hydrological impacts. River ice and floods limit the availability of the waterway network and may cause considerable damages to waterway infrastructure. Low flows significantly affect IWT's operation efficiency usually several months a year due to the close correlation of (low) water levels / water depths and (high) transport costs. Therefore "navigation-related" hydrological forecasts focussing on the specific requirements of water-bound transport (relevant forecast locations, target parameters, skill characteristics etc.) play a major role in order to mitigate IWT's vulnerability to hydro-meteorological impacts. In light of continuing transport growth within the European Union, hydrological forecasts for the waterways are essential to stimulate the use of the free capacity IWT still offers more consequently. An overview of the current operational and pre-operational forecasting systems for the German waterways predicting water levels, discharges and river ice thickness on various time-scales will be presented. While short-term (deterministic) forecasts have a long tradition in navigation-related forecasting, (probabilistic) forecasting services offering extended lead-times are not yet well-established and are still subject to current research and development activities (e.g. within the EU-projects EUPORIAS and IMPREX). The focus is on improving technical aspects as well as on exploring adequate ways of disseminating and communicating probabilistic forecast information. For the German stretch of the River Rhine, one of the most frequented inland waterways worldwide, the existing deterministic forecast scheme has been extended by ensemble forecasts combined with statistical post-processing modules applying EMOS (Ensemble Model Output Statistics) and ECC (Ensemble Copula Coupling) in order to generate water level predictions up to 10 days and to estimate its predictive uncertainty properly. Additionally for the key locations at the international waterways Rhine, Elbe and Danube three competing forecast approaches are currently tested in a pre-operational set-up in order to generate monthly to seasonal (up to 3 months) forecasts: (1) the well-known Ensemble Streamflow Prediction approach (ensemble based on historical meteorology), (2) coupling hydrological models with post-processed outputs from ECMWF's general circulation model (System 4), and (3) a purely statistical approach based on the stable relationship (teleconnection) of global or regional oceanic, climate and hydrological data with river flows. The current results, still pre-operational, reveal the existence of a valuable predictability of water levels and streamflow also at monthly up to seasonal time-scales along the larger rivers used as waterways in Germany. Last but not least insight into the technical set-up of the aforementioned forecasting systems operated at the Federal Institute of Hydrology, which are based on a Delft-FEWS application, will be given focussing on the step-wise extension of the former system by integrating new components in order to meet the growing needs of the customers and to improve and extend the forecast portfolio for waterway users.

Erosion patterns produced by the paleo Haizishan ice cap, SE Tibetan Plateau

NASA Astrophysics Data System (ADS)

Fu, P.; Stroeven, A. P.; Harbor, J.; Hättestrand, C.; Heyman, J.; Caffee, M. W.

2017-12-01

Erosion is a primary driver of landscape evolution, topographic relief production, geochemical cycles, and climate change. Combining in situ 10Be and 26Al exposure age dating, geomorphological mapping, and field investigations, we examine glacial erosion patterns of the almost 4,000 km2 paleo Haizishan ice cap on the southeastern Tibetan Plateau. Our results show that ice caps on the low relief Haizishan Plateau produced a zonal pattern of landscape modification. In locations where apparent exposure ages on bedrock are consistent with the last deglaciation, complete resetting of the cosmogenic exposure age clock indicates glacial erosion of at least a few meters. However, older apparent exposure ages on bedrock in areas known to have been covered by the paleo ice cap during the Last Glacial Maximum indicate inheritance and thus limited glacial erosion. Inferred surface exposure ages from cosmogenic depth profiles through two saprolites vary from resetting and thus saprolite profile truncation to nuclide inheritance indicating limited erosion. Finally, significant nuclide inheritance in river sand samples from basins on the scoured plateau surface also indicate limited glacial erosion during the last glaciation. Hence, for the first time, our study shows clear evidence of preservation under non-erosive ice on the Tibetan Plateau. As patterns of glacial erosion intensity are largely driven by the basal thermal regime, our results confirm earlier inferences from geomorphology for a concentric basal thermal pattern for the paleo Haizishan ice cap during the LGM.

The dynamic response of Kennicott Glacier, Alaska, USA, to the Hidden Creek Lake outburst flood

USGS Publications Warehouse

Anderson, R. Scott; Walder, J.S.; Anderson, S.P.; Trabant, D.C.; Fountain, A.G.

2005-01-01

Glacier sliding is commonly linked with elevated water pressure at the glacier bed. Ice surface motion during a 3 week period encompassing an outburst of ice-dammed Hidden Creek Lake (HCL) at Kennicott Glacier, Alaska, USA, showed enhanced sliding during the flood. Two stakes, 1.2 km from HCL, revealed increased speed in two episodes, both associated with uplift of the ice surface relative to the trajectory of bed-parallel motion. Uplift of the surface began 12 days before the flood, initially stabilizing at a value of 0.25 m. Two days after lake drainage began, further uplift (reaching 0.4 m) occurred while surface speed peaked at 1.2 m d-1. Maximum surface uplift coincided with peak discharge from HCL, high water level in a down-glacier ice-marginal basin, and low solute concentrations in the Kennicott River. Each of these records is consistent with high subglacial water pressure. We interpret the ice surface motion as arising from sliding up backs of bumps on the bed, which enlarges cavities and produces bed separation. The outburst increased water pressure over a broad region, promoting sliding, inhibiting cavity closure, and blocking drainage of solute-rich water from the distributed system. Pressure drop upon termination of the outburst drained water from and depressurized the distributed system, reducing sliding speeds. Expanded cavities then collapsed with a 1 day time-scale set by the local ice thickness.

Spatial-altitudinal and temporal variation of Degree Day Factors (DDFs) in the Upper Indus Basin

NASA Astrophysics Data System (ADS)

Khan, Asif; Attaullah, Haleema; Masud, Tabinda; Khan, Mujahid

2017-04-01

Melt contribution from snow and ice in the Hindukush-Karakoram-Himalayan (HKH) region could account for more than 80% of annual river flows in the Upper Indus Basin (UIB). Increase or decrease in precipitation, energy input and glacier reserves can significantly affect water resources of this region. Therefore improved hydrological modelling and accurate future water resources prediction are vital for food production and hydro-power generation for millions of people living downstream, and are intensively needed. In mountain regions Degree Day Factors (DDFs) significantly vary on spatial and altitudinal basis, and are primary inputs of temperature-based hydrological modelling. However previous studies have used different DDFs as calibration parameters without due attention to the physical meaning of the values employed, and these estimates possess significant variability and uncertainty. This study provides estimates of DDFs for various altitudinal zones in the UIB at sub-basin level. Snow, clean ice and ice with debris cover bear different melt rates (or DDFs), therefore areally-averaged DDFs based on snow, clean and debris-covered ice classes in various altitudinal zones have been estimated for all sub-basins of the UIB. Zonal estimates of DDFs in the current study are significantly different from earlier adopted DDFs, hence suggest a revisit of previous hydrological modelling studies. DDFs presented in current study have been validated by using Snowmelt Runoff Model (SRM) in various sub-basins with good Nash Sutcliffe coefficients (R2 > 0.85) and low volumetric errors (Dv<10%). DDFs and methods provided in the current study can be used in future improved hydrological modelling and to provide accurate predictions of future river flows changes. The methodology used for estimation of DDFs is robust, and can be adopted to produce such estimates in other regions of the, particularly in the nearby other HKH basins.

Erosion by Ice and Water in the Southern Andes

NASA Technical Reports Server (NTRS)

2002-01-01

This scene on the remote, rugged Argentine/Chilean border in the far southern Andes Mountains offers numerous, dramatic examples of both erosional processes and features of ice and water. The sharp, glaciated crest of the Cerro San Lorenzo (center) exceeds 12,000 feet and casts a long shadow southeastward. Glaciers on its western flank flow into the valley. This Electronic Still Camera photo was taken from the International Space Station, in December 2000 (late spring) when most of the previous winter's snow had melted below an altitude of 6,000 feet. Lago Pueyrredon, and the other lakes visible here, have been excavated by geologically recent episodes of glacier erosion, when glaciers extended all the way onto the lowland plains (top right). Since the last melting of the glaciers (15,000 years ago) three distinct fan deltas (semicircular features, marked with arrows) have formed where rivers flow into the lake. Counterclockwise currents in the lake-driven by strong winds from the west-have generated thin sand spits from each fan-delta. The largest spit (attached to the largest fan-delta, see right arrow) has isolated an approximately 10-kilometer long segment of the south end of the lake. The river that constructed the largest fan presently discharges turbid water to this isolated basin, giving it a lighter color than the rest of the lake. Glacial data collected over the past 50 years indicate that small ice bodies are disappearing at accelerated rates. (EOS, vol 81, no. 24, June 13, 2000) Predictions are that large fluctuations in land ice, with significant implications to society, are possible in the coming decades and centuries due to natural and anthropogenic climate change. Before glacial data can be used to address critical problems pertaining to the world's economic and environmental health, more detailed information about such glaciers is needed. Image ISS001-ESC-5113 provided by the Earth Sciences and Image Analysis Laboratory, Johnson Space Center.

Early density management of longleaf pine reduces susceptibility to ice storm damage

Treesearch

Timothy B. Harrington; Thaddeus A. Harrington

2016-01-01

The Pax winter storm of February 2014 caused widespread damage to forest stands throughout the southeastern U.S. In a long-term study of savanna plant community restoration at the Savannah River Site, Aiken, SC, precommercial thinning (PCT) of 8- to 11-year-old plantations of longleaf pine (Pinus palustris) in 1994 reduced...

The Rivers Run Down to the Sea: Safety for Small Boats.

ERIC Educational Resources Information Center

Keller, Rosanne

Part of a series of home literacy readers with conversational text and sketches, this booklet addresses water safety in the Alaskan summer environment. Alaskan villages are generally located near slough, creek, lake or ocean. At the end of winter, the ice floes go out, and where there was snow there is water. Summer activities include use of…

HIMALA: climate impacts on glaciers, snow, and hydrology in the Himalayan region

USGS Publications Warehouse

Brown, Molly Elizabeth; Ouyang, Hua; Habib, Shahid; Shrestha, Basanta; Shrestha, Mandira; Panday, Prajjwal; Tzortziou, Maria; Policelli, Frederick; Artan, Guleid; Giriraj, Amarnath; Bajracharya, Sagar R.; Racoviteanu, Adina

2010-01-01

Glaciers are the largest reservoir of freshwater on Earth, supporting one third of the world's population. The Himalaya possess one of the largest resources of snow and ice, which act as a freshwater reservoir for more than 1.3 billion people. This article describes a new project called HIMALA, which focuses on utilizing satellite-based products for better understanding of hydrological processes of the river basins of the region. With support from the US Agency for International Development (USAID), the International Centre for Integrated Mountain Development (ICIMOD), together with its partners and member countries, has been working on the application of satellite-based rainfall estimates for flood prediction. The US National Aeronautics and Space Administration (NASA) partners are working with ICIMOD to incorporate snowmelt and glacier melt into a widely used hydrological model. Thus, through improved modeling of the contribution of snow and ice meltwater to river flow in the region, the HIMALA project will improve the ability of ICIMOD and its partners to understand the impact of weather and climate on floods, droughts, and other water- and climate-induced natural hazards in the Himalayan region in Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal, and Pakistan.

Multispectral remote observations of hydrologic features on the North Slope of Alaska

NASA Technical Reports Server (NTRS)

Hall, D. K.; Bryan, M. L.

1977-01-01

Visible and near-infrared satellite data and active and passive microwave aircraft data are used to analyze some hydrologic features in Arctic Alaska. The following features have been studied: the small thaw lakes on the Arctic Coastal Plain (oriented lakes), Chandalar Lake in the Brooks Range, several North Slope rivers, surface water on the tundra, and snowcover on the North Slope and in the Brooks Range. Passive microwave brightness temperatures (T sub b) as seen on Electrically Scanned Microwave Radiometer (ESMR) imagery are shown to increase with increasing ice thickness on all of the lakes studied. Aufeis, an important hydrologic parameter in the Arctic, is observable in the Sagavanirktok River channel on April ESMR imagery. LANDSAT imagery with better (80 m) resolution is useful for measuring aufeis extent using band 5 imagery obtained just after snowmelt in June. It is shown that the extent of aufeis (as measured on LANDSAT imagery) varies with meteorological conditions and, therefore, may be a useful indicator of annual climate fluctuations on the North Slope. Snow and ice breakup has been traced from the Brooks Range Mountains to the Arctic Ocean Coast using LANDSAT band 7 imagery in May when melting begins in the mountains.

Geohydrology of the valley-fill aquifer in the Bath area, Lower Cohocton River, Steuben County, New York

USGS Publications Warehouse

Pagano, Timothy S.; Terry, D.B.; Shaw, M.L.; Ingram, A.W.

1984-01-01

The Bath valley-fill aquifer, southern New York, composed of outwash, ice-contact, and ice-disintegration sand and gravel, is highly productive and is in many areas in hydraulic contact with the Cohocton River. Potential well yields range 50 to more than 1,000 gallons per minute. Most of the aquifer is under shallow water-table conditions and vulnerable to surface contamination. Thickness ranges from 20 to 40 feet. Buried aquifers are present locally. The aquifer system underlies an area containing only a few small communities and therefore is not heavily pumped. Geohydrologic data are compiled on six maps at 1:24,000 scale and on a sheet of geologic sections. The maps depict surficial geology, soil-infiltration capacity, potentiometric surface, aquifer thickness, well yields, and land use. This map report set is one in a series of four that depict selected aquifers in Wester New York. It supplements a series that is being done by the U.S. Geological Survey in cooperation with State agencies. The maps are based largely on published reports, data filled in several State agencies, and some additional field data collection. (USGS)

HIMALA: Climate Impacts on Glaciers, Snow, and Hydrology in the Himalayan Region

NASA Technical Reports Server (NTRS)

Brown, Molly Elizabeth; Ouyang, Hua; Habib, Shahid; Shrestha, Basanta; Shrestha, Mandira; Panday, Prajjwal; Tzortziou, Maria; Policelli, Frederick; Artan, Guleid; Giriraj, Amarnath;

High-Resolution in Situ Measurement of Nitrate in Runoff from the Greenland Ice Sheet.

PubMed

Beaton, Alexander D; Wadham, Jemma L; Hawkings, Jon; Bagshaw, Elizabeth A; Lamarche-Gagnon, Guillaume; Mowlem, Matthew C; Tranter, Martyn

2017-11-07

We report the first in situ high-resolution nitrate time series from two proglacial meltwater rivers draining the Greenland Ice Sheet, using a recently developed submersible analyzer based on lab-on-chip (LOC) technology. The low sample volume (320 μL) required by the LOC analyzer meant that low concentration (few micromolar to submicromolar), highly turbid subglacial meltwater could be filtered and colorimetrically analyzed in situ. Nitrate concentrations in rivers draining Leverett Glacier in southwest Greenland and Kiattuut Sermiat in southern Greenland exhibited a clear diurnal signal and a gradual decline at the commencement of the melt season, displaying trends that would not be discernible using traditional daily manual sampling. Nitrate concentrations varied by 4.4 μM (±0.2 μM) over a 10 day period at Kiattuut Sermiat and 3.0 μM (±0.2 μM) over a 14 day period at Leverett Glacier. Marked changes in nitrate concentrations were observed when discharge began to increase. High-resolution in situ measurements such as these have the potential to significantly advance the understanding of nutrient cycling in remote systems, where the dynamics of nutrient release are complex but are important for downstream biogeochemical cycles.

Valley-fill alluviation during the Little Ice Age (ca. A.D. 1400-1880), Paria River basin and southern Colorado Plateau, United States

USGS Publications Warehouse

Hereford, R.

2002-01-01

Valley-fill alluvium deposited from ca. A.D. 1400 to 1880 is widespread in tributaries of the Paria River and is largely coincident with the Little Ice Age epoch of global climate variability. Previous work showed that alluvium of this age is a mappable stratigraphic unit in many of the larger alluvial valleys of the southern Colorado Plateau. The alluvium is bounded by two disconformities resulting from prehistoric and historic arroyo cutting at ca. A.D. 1200-1400 and 1860-1910, respectively. The fill forms a terrace in the axial valleys of major through-flowing streams. This terrace and underlying deposits are continuous and interfinger with sediment in numerous small tributary valleys that head at the base of hillslopes of sparsely vegetated, weakly consolidated bedrock, suggesting that eroded bedrock was an important source of alluvium along with in-channel and other sources. Paleoclimatic and high-resolution paleoflood studies indicate that valley-fill alluviation occured during a long-term decrease in the frequency of large, destructive floods. Aggradation of the valleys ended about A.D. 1880, if not two decades earlier, with the beginning of historic arroyo cutting. This shift from deposition to valley entrenchment near the close of the Little Ice Age generally coincided with the beginning of an episode of the largest floods in the preceding 400-500 yr, which was probably caused by an increased recurrence and intensity of flood-producing El Nin??o events beginning at ca. A.D. 1870.

[Aquatic Ecological Index based on freshwater (ICE(RN-MAE)) for the Rio Negro watershed, Colombia].

PubMed

Forero, Laura Cristina; Longo, Magnolia; John Jairo, Ramirez; Guillermo, Chalar

2014-04-01

Aquatic Ecological Index based on freshwater (ICE(RN-MAE)) for the Rio Negro watershed, Colombia. Available indices to assess the ecological status of rivers in Colombia are mostly based on subjective hypotheses about macroinvertebrate tolerance to pollution, which have important limitations. Here we present the application of a method to establish an index of ecological quality for lotic systems in Colombia. The index, based on macroinvertebrate abundance and physicochemical variables, was developed as an alternative to the BMWP-Col index. The method consists on determining an environmental gradient from correlations between physicochemical variables and abundance. The scores obtained in each sampling point are used in a standardized correlation for a model of weighted averages (WA). In the WA model abundances are also weighted to estimate the optimum and tolerance values of each taxon; using this information we estimated the index of ecological quality based also on macroinvertebrate (ICE(RN-MAE)) abundance in each sampling site. Subsequently, we classified all sites using the index and concentrations of total phosphorus (TP) in a cluster analysis. Using TP and ICE(RN-MAE), mean, maximum, minimum and standard deviation, we defined threshold values corresponding to three categories of ecological status: good, fair and critical.

Hypsometric Amplification of Greenland Ice Sheet Meltwater Release

NASA Astrophysics Data System (ADS)

van As, D.; Hasholt, B.; Mikkelsen, A. B.; Holtegaard Nielsen, M.; Box, J.; Claesson Liljedahl, L.; Lindback, K.; Pitcher, L. H.

2017-12-01

Proglacial discharge monitoring provides valuable insights in Greenland ice sheet meltwater release. We use a 2006-2016 discharge time series from the Watson River draining 12000 km2 of the ice sheet in southwest Greenland to investigate the large variability in catchment-total meltwater production. An observationally-constrained reconstruction of past discharge shows that meltwater release has on average increased by a factor of 1.5 since 2003 compared to the 1949-2002 period, and that interannual variability has disproportionally increased by a factor of 2.1, suggesting that melt amplifiers are at play. We derive a hypsometric amplification factor of 1.6, which is the result of the exponential melt area increase with rising temperature. Peak meltwater discharge events such as during the July 2012 flooding are due to this and other melt amplifiers, but also require intense melting over a period exceeding the multi-day transit time for high-elevation meltwater to pass through the glacial drainage system.

Diatom evidence on Wisconsin and Holocene events in the Bering Sea

USGS Publications Warehouse

Sancetta, C.; Robinson, S.W.

1983-01-01

Previous work on surface (modern) sediments has defined diatom species which appear to be good indicators of various oceanographic/ecologic conditions in the North Pacific Ocean and marginal seas. Three long cores from the eastern and northern sides of the Aleutian Basin show changes in species assemblage which can be interpreted in terms of changes in the ocean environment during the last glaciation (Wisconsin) and the Holocene. The early and late Wisconsin maxima were times of prolonged annual sea-ice cover and a short cool period of phytoplankton productivity during the ice-free season. The middle Wisconsin interstade, at least in the southern Bering Sea, had greater seasonal contrast than today, with some winter sea-ice cover, an intensified temperature minimum, and high spring productivity. Variations in clastic and reworked fossil material imply varying degrees of transport to the basin by Alaskan rivers. The results of Jouse?? from the central Bering Sea generally correspond with those presented here, although there are problems with direct comparison. ?? 1983.

Comparing a thermo-mechanical Weichselian ice sheet reconstruction to GIA driven reconstructions: aspects of earth response and ice configuration

NASA Astrophysics Data System (ADS)

Schmidt, P.; Lund, B.; Näslund, J.-O.

2013-12-01

In this study we compare a recent reconstruction of the Weichselian ice-sheet as simulated by the University of Main ice-sheet model (UMISM) to two reconstructions commonly used in glacial isostatic adjustment (GIA) modeling: ICE-5G and ANU (also known as RSES). The UMISM reconstruction is carried out on a regional scale based on thermo-mechanical modelling whereas ANU and ICE-5G are global models based on the sea-level equation. The Weichselian ice-sheet in the three models are compared directly in terms of ice volume, extent and thickness, as well as in terms of predicted glacial isostatic adjustment in Fennoscandia. The three reconstructions display significant differences. UMISM and ANU includes phases of pronounced advance and retreat prior to the last glacial maximum (LGM), whereas the thickness and areal extent of the ICE-5G ice-sheet is more or less constant up until LGM. The final retreat of the ice-sheet initiates at earliest time in ICE-5G and latest in UMISM, while ice free conditions are reached earliest in UMISM and latest in ICE-5G. The post-LGM deglaciation style also differs notably between the ice models. While the UMISM simulation includes two temporary halts in the deglaciation, the later during the Younger Dryas, ANU only includes a decreased deglaciation rate during Younger Dryas and ICE-5G retreats at a relatively constant pace after an initial slow phase. Moreover, ANU and ICE-5G melt relatively uniformly over the entire ice-sheet in contrast to UMISM which melts preferentially from the edges. We find that all three reconstructions fit the present day uplift rates over Fennoscandia and the observed relative sea-level curve along the Ångerman river equally well, albeit with different optimal earth model parameters. Given identical earth models, ICE-5G predicts the fastest present day uplift rates and ANU the slowest, ANU also prefers the thinnest lithosphere. Moreover, only for ANU can a unique best fit model be determined. For UMISM and ICE-5G there is a range of earth models that can reproduce the present day uplift rates equally well. This is understood from the higher present day uplift rates predicted by ICE-5G and UMISM, which results in a bifurcation in the best fit mantle viscosity. Comparison of the uplift histories predicted by the ice-sheets indicate that inclusion of relative sea-level data in the data fit can reduce the observed ambiguity. We study the areal distributions of present day residual surface velocities in Fennoscandia and show that all three reconstructions generally over-predict velocities in southwestern Fennoscandia and that there are large differences in the fit to the observational data in Finland and northernmost Sweden and Norway. These difference may provide input to further enhancements of the ice-sheet reconstructions.

Remote identification of polar bear maternal den habitat in northern Alaska

USGS Publications Warehouse

Durner, George M.; Amstrup, Steven C.; Ambrosius, Ken J.

2001-01-01

Polar bears (Ursus maritimus) give birth in dens of ice and snow to protect their altricial young. During the snow-free season, we visited 25 den sites located previously by radiotelemetry and characterized the den site physiognomy. Seven dens occurred in habitats with minimal relief. Eighteen dens (72%) were in coastal and river banks. These "banks" were identifiable on aerial photographs. We then searched high-resolution aerial photographs (n = 3000) for habitats similar to those of the 18 dens. On aerial photos, we mapped 1782 km of bank habitats suitable for denning. Bank habitats comprised 0.18% of our study area between the Colville River and the Tamayariak River in northern Alaska. The final map, which correctly identified 88% of bank denning habitat in this region, will help minimize the potential for disruptions of maternal dens by winter petroleum exploration activities.

Occurrence of benzotriazoles in the rivers Main, Hengstbach, and Hegbach (Germany).

PubMed

Kiss, Aliz; Fries, Elke

2009-09-01

Benzotriazoles (BT) as 1H-benzotriazole (1H-BT), 5-methyl-1H-benzotriazole (5Me-BT), and 4-methyl-1H-benzotriazole (4Me-BT) are frequently used as corrosion inhibitors in dish washer detergents, aircraft de-icing/anti-icing fluids (ADAF), automotive antifreeze formulations, brake fluids, fluids for industrial cooling systems, metal-cutting fluids, and in solid cooling lubricants. Discharge of treated municipal waste water and controlled over-runs of combined waste water sewers are potential point sources for BT in rivers. The aim of this monitoring study was to yield an overview on exposure concentrations and loads of BT in the German rivers Main, Hengstbach, and Hegbach. Concentrations of 1H-BT, 5Me-BT, and 4Me-BT were determined in grab samples collected from different sampling points in the rivers Main, Hengstbach, and Hegbach at four different sampling times. Main and Hengstbach rivers were sampled close to Frankfurt International Airport. Both rivers receive domestic waste water effluents. BT were extracted from 2.5 L of river water by solid phase extraction using Bond Elut ppl cartridges (200 mg/3 mL). The extracts were analyzed by gas chromatography/mass spectrometry in full scan mode. Mass flows of BT were calculated by concentrations multiplied by mean daily river flow rates. Median concentrations and mass flows were compared for different rivers. Mass flows were also compared for selected sampling points at different sampling times. 1H-BT, 5Me-BT, and 4Me-BT were detected in Main and Hengstbach rivers. 1H-BT and 5Me-BT were also detected in Hegbach River. Concentrations ranged from 38 to 1,474 ng/L for 1H-BT, from 25 to 281 ng/L for 5Me-BT, and from 25 to 952 ng/L for 4Me-BT. Median concentrations of 1H-BT, 5Me-BT, and 4Me-BT were lower in Main than in Hengstbach River. Much higher median mass flows of all BT were calculated for Main than for Hengstbach River. At sampling points P9 (Main) and P5 (Hengstbach) concentrations of 4Me-BT and 5Me-BT increased from March 29, 2008 to May 1, 2008 to June 22, 2008 whereas daily mean river flow rate decreased simultaneously. However, concentration of 1H-BT in Main and Hengstbach River increased from March 29, 2008 to May 1, 2008 and decreased again on June 22, 2008. In the Main River, lowest and highest mass flows for all BT were calculated on June 22, 2008 and May 1, 2008, respectively. In the Hengstbach River lowest and highest mass flows for 1H-BT and 4Me-BT were also calculated on June 22, 2008 and May 1, 2008, respectively. However, mass flows of 5Me-BT in Hengstbach River were rather similar at all three sampling times. In all grab samples, 1H-BT was more abundant than 5Me-BT and 4Me-BT in Main and Hengstbach River, except on June 22, 2008. Ratios of 1H-BT/(5Me-BT + 4Me-BT) determined on March 15, 2008, March 29, 2008, and May 1, 2008 varied between 1.6 and 9.0 with a median value of 1.9 (n = 9) whereas on June 22, 2008 the ratios varied between 0.4 and 0.7 with a median value of 0.6 (n = 5). Due to the absence of waste water effluents in the Hegbach River, other input sources as controlled over-runs of combined waste water sewers and/or atmospheric deposition of BT must be regarded as possible input sources. Exfiltration of ground water containing BT to Hegbach River must be also regarded, especially when considering the high polarity of BT. Median concentrations of BT in Main River were much lower than in Hengstbach River due to dilution. However, median mass flows were higher in the Main River than in the Hengstbach River. Higher mass flows could be attributed to higher source strengths and/or numerous emissions sources in the Main River. Mass flows determined on June 22, 2008 in Main and Hengstbach rivers probably reflect emissions of BT only from dishwasher detergents since de-icing operations were unlikely at that time. Emissions of BT from dish washer detergents are rather constant without any seasonal variations. Assuming the absence of additional input sources and constant in-stream removal processes, mass flows calculated for all other sampling times must be nearly similar to mass flows for June 22, 2009 as it was only observed for 5Me-BT in Hengstbach River. The higher mass flows for 1H-BT and 4Me-BT in March and May in both rivers could be an indication for temporal variations of emission pattern and/or of in-stream removal processes. 1H-BT/(4Me-BT + 5Me-BT) ratios above one in March and May and below one in June could be also an indication for temporal variations of input and/or removal processes. 1H-BT, 5Me-BT, and 4Me-BT used as corrosion inhibitors in many applications were detected in the rivers Main, Hengstbach, and Hegbach with relative high temporal and spatial concentration variations. Dilution is a dominant factor that influences exposure concentrations of BT in the studied rivers. We conclude that, especially in smaller rivers (as Hengstbach River), the hydrological situation has to be regarded when predicting exposure concentrations of BT. Characteristic emission strength and in-stream removal processes must be known to relate loads of BT in river water to different sources. The ratio of 1H-BT/(4Me-BT + 5Me-BT) could be possibly used for source apportionment. Time series analyses of BT in composite river water samples collected at two river sites of the Hengstbach/Schwarzbach catchment area, without any waste water effluents in between, are recommended to study in-stream removal of BT. In addition, exposure modeling is recommended of BT, regarding all input sources and in-stream removal processes to predict exposure concentrations of BT in rivers. In order to calibrate and validate the model, additional monitoring data are required.

Volcano hazards in the Mount Hood region, Oregon

USGS Publications Warehouse

Scott, W.E.; Pierson, T.C.; Schilling, S.P.; Costa, J.E.; Gardner, C.A.; Vallance, J.W.; Major, J.J.

1997-01-01

Mount Hood is a potentially active volcano close to rapidly growing communities and recreation areas. The most likely widespread and hazardous consequence of a future eruption will be for lahars (rapidly moving mudflows) to sweep down the entire length of the Sandy (including the Zigzag) and White River valleys. Lahars can be generated by hot volcanic flows that melt snow and ice or by landslides from the steep upper flanks of the volcano. Structures close to river channels are at greatest risk of being destroyed. The degree of hazard decreases as height above a channel increases, but large lahars can affect areas more than 30 vertical meters (100 vertical feet) above river beds. The probability of eruption-generated lahars affecting the Sandy and White River valleys is 1-in-15 to l-in-30 during the next 30 years, whereas the probability of extensive areas in the Hood River Valley being affected by lahars is about ten times less. The accompanying volcano-hazard-zonation map outlines areas potentially at risk and shows that some areas may be too close for a reasonable chance of escape or survival during an eruption. Future eruptions of Mount Hood could seriously disrupt transportation (air, river, and highway), some municipal water supplies, and hydroelectric power generation and transmission in northwest Oregon and southwest Washington.

Rangewide glaciation in the Sierra Nevada, California

USGS Publications Warehouse

Moore, James G.; Moring, Barry C.

2013-01-01

The 600-km-long Sierra Nevada underwent extensive Pleistocene glaciation except for its southernmost 100 km. Presently, ∼1700 small glaciers and ice masses near the crest of the range occur above 3250 m in elevation; these covered an area of ∼50 km2 in 1972. Fourteen of the largest glaciers decreased by about one half in area during the period from 1900 to 2004.Rock glaciers, generally glacial ice covered by 1–10 m of rockfall debris, occur in about the same span of the range as ice and permanent snowfields. They are, on average, lower by 200–300 m, apparently because of the insulating layer of rocky rubble that protects their internal ice from the sun’s heat and from wind.The principal Pleistocene glacial stages are the Sherwin (ca. 820 ka), Tahoe (170–130 and ca. 70 ka), Tioga (14–28 ka), and Recess Peak (13 ka). Some 7040 glacial lakes, produced primarily by quarrying from bedrock, were mostly exposed after recession of the Tioga glacial stage. The lakes largely mark the area of primary snow accumulation. Below the lower limit of the lakes, ice flowed downward into river-cut canyons, forming major trunk glaciers within the zone of ablation.The range is in general a westward-tilted block upfaulted on its east side. Therefore, the main late Pleistocene trunk glaciers (Tahoe/Tioga) west of the crest extend 25–60 km, whereas those east of the crest extend only 5–20 km. Because of higher precipitation northward, glacial features such as the toes of existing glaciers and rock glaciers, as well as the late season present-day snowline, all decrease in elevation northward. Likewise, the elevation of the lower limit of glacial lakes, an indication of the zone of snow accumulation during the late Pleistocene, decreases about the same degree. This similarity suggests that the overall climate patterns of the late Pleistocene, though cooler, were similar to those of today. The east slope glaciers show a similar northward depression, but they are ∼500–1000 m higher.The upper part of the glacial system was erosive over a broad highland area as the evenly distributed ice in the accumulation zone moved to lower elevation. The abundant lake basins record this erosive action. The lower part of the glacier system was largely confined to major preexisting river canyons in which melting dominated. The average of rangewide estimates of the equilibrium line altitude (ELA)—the boundary between the upper snow and ice accumulation zone and the lower ablation zone—of many late Pleistocene glaciers parallels, and is only 200–300 m above, the altitude of the lower limit of the lakes. Hence, the lake zone provides a means of estimating the ELA.

Late winter under ice pelagic microbial communities in the high Arctic Ocean and the impact of short-term exposure to elevated CO2 levels

PubMed Central

Monier, Adam; Findlay, Helen S.; Charvet, Sophie; Lovejoy, Connie

2014-01-01

Polar Oceans are natural CO2 sinks because of the enhanced solubility of CO2 in cold water. The Arctic Ocean is at additional risk of accelerated ocean acidification (OA) because of freshwater inputs from sea ice and rivers, which influence the carbonate system. Winter conditions in the Arctic are of interest because of both cold temperatures and limited CO2 venting to the atmosphere when sea ice is present. Earlier OA experiments on Arctic microbial communities conducted in the absence of ice cover, hinted at shifts in taxa dominance and diversity under lowered pH. The Catlin Arctic Survey provided an opportunity to conduct in situ, under-ice, OA experiments during late Arctic winter. Seawater was collected from under the sea ice off Ellef Ringnes Island, and communities were exposed to three CO2 levels for 6 days. Phylogenetic diversity was greater in the attached fraction compared to the free-living fraction in situ, in the controls and in the treatments. The dominant taxa in all cases were Gammaproteobacteria but acidification had little effect compared to the effects of containment. Phylogenetic net relatedness indices suggested that acidification may have decreased the diversity within some bacterial orders, but overall there was no clear trend. Within the experimental communities, alkalinity best explained the variance among samples and replicates, suggesting subtle changes in the carbonate system need to be considered in such experiments. We conclude that under ice communities have the capacity to respond either by selection or phenotypic plasticity to heightened CO2 levels over the short term. PMID:25324832

Influences of glacial melt and permafrost thaw on the age of dissolved organic carbon in the Yukon River basin

USGS Publications Warehouse

Aiken, George R.; Spencer, Robert G.M.; Striegl, Robert G.; Schuster, Paul F.; Raymond, Peter A.

2014-01-01

Responses of near-surface permafrost and glacial ice to climate change are of particular significance for understanding long-term effects on global carbon cycling and carbon export by high-latitude northern rivers. Here we report Δ14C-dissolved organic carbon (DOC) values and dissolved organic matter optical data for the Yukon River, 15 tributaries of the Yukon River, glacial meltwater, and groundwater and soil water end-member sources draining to the Yukon River, with the goal of assessing mobilization of aged DOC within the watershed. Ancient DOC was associated with glacial meltwater and groundwater sources. In contrast, DOC from watersheds dominated by peat soils and underlain by permafrost was typically enriched in Δ14C indicating that degradation of ancient carbon stores is currently not occurring at large enough scales to quantitatively influence bulk DOC exports from those landscapes. On an annual basis, DOC exported was predominantly modern during the spring period throughout the Yukon River basin and became older through summer-fall and winter periods, suggesting that contributions of older DOC from soils, glacial meltwaters, and groundwater are significant during these months. Our data indicate that rapidly receding glaciers and increasing groundwater inputs will likely result in greater contributions of older DOC in the Yukon River and its tributaries in coming decades.

Hydro power plants on the Middle Sava River section

NASA Astrophysics Data System (ADS)

Kryžanowski, A.; Horvat, A.; Brilly, M.

2008-11-01

Construction of a chain of hydro power plants is planned on the Sava River from Medvode to the Slovenian-Croatian border which will, apart from the chain of HPPs on the Drava River, represent the linchpin of renewable energy production within the Slovenian power system. The mentioned chain of HPPs will also be one of the country's main renewable energy sources that can still be developed for power generation. Three hydro power plants, Moste, Mavčciče and Medvode, are already operating on the Upper Sava River section. Construction of the chain is underway in the lower part of the stream where Vrhovo and Bošstanj HPPs are already in operation; HPP Blanca is under construction and the site planning procedures are taking place for Krško, Brežice and Mokrice HPPs. The planned HPPs on the Middle Sava River section between Medvode and Zidani most will connect the HPPs on the Upper and Lower Sava River into a closed chain which will operate on the principle of run-of-river type power plants with daily storage. Completion of all stages will enable optimal development of available hydro potential. Apart from the energy effects, also other beneficial effects of hydro power plant construction in the region can be expected: flood protection; better water supply; waste water treatment; development of transport and energy networks as well as positive economic and social effects.

Morphodynamics of the Kulsi River Basin in the northern front of Shillong Plateau: Exhibiting episodic inundation and channel migration

NASA Astrophysics Data System (ADS)

Imsong, Watinaro; Choudhury, Swapnamita; Phukan, Sarat; Duarah, Bhagawat Pran

2018-02-01

The present study is undertaken in the Kulsi River valley, a tributary of the Brahmaputra River that drains through the tectonically active Shillong Plateau in northeast India. Based on the fluvial geomorphic parameters and Landsat satellite images, it has been observed that the Kulsi River migrated 0.7-2 km westward in its middle course in the past 30 years. Geomorphic parameters such as longitudinal profile analysis, stream length gradient index ( SL), ratio of valley floor width to valley height ( Vf), steepness index (ks) indicate that the upstream segment of the Kulsi River is tectonically more active than the downstream segment which is ascribed to the tectonic activities along the Guwahati Fault. ^{14}C ages obtained from the submerged tree trunks of the Chandubi Lake, which is located in the central part of the Kulsi River catchment suggests inundation (high lake levels) during 160 ± 50 AD, 970 ± 50 AD, 1190 ± 80 AD and 1520 ± 30 AD, respectively. These periods broadly coincide with the late Holocene strengthened Indian Summer Monsoon (ISM), Medieval Warm Period (MWP) and the early part of the Little Ice Age (LIA). The debris which clogged the course of the river in the vicinity of the Chandubi Lake is attributed to tectonically induced increase in sediment supply during high magnitude flooding events.

Radar Altimetry for Inland Water: Current and Potential Applications

NASA Astrophysics Data System (ADS)

Tarpanelli, Angelica; Brocca, Luca; Barbetta, Silvia; Moramarco, Tommaso; da Silva, Joecila Santos; Calmant, Stephane

2015-12-01

Apart from oceans and ice-sheets, radar altimeters are shown by a plethora of works to be of considerable interest in monitoring inland water bodies such as rivers, lakes, wetlands and floodplains. More than a decade of research on the application in the field of continental hydrology has demonstrated the advantages of providing global coverage, regular temporal sampling and short delivery delays, especially via the acquisition of numerous useful measurements over ungauged areas. With the aim to investigate the benefits that can be achieved by Sentinel-3 mission, two applications are here shown for selected pilot rivers and the results on discharge estimation are analyzed and discussed in terms of performance measures.

A review of water resources of the Umiat area, northern Alaska

USGS Publications Warehouse

Williams, John R.

1970-01-01

Surface-water supplies from the Colville River, small tributary creeks, and lakes are abundant in summer but limited in winter by low or zero flow in streams and thick ice cover on lakes. Fresh ground water occurs in unfrozen zones in alluvium and in the upper part of bedrock beneath the Colville River and beneath lakes that do not freeze to the bottom in winter. These unfrozen zones, forming depressions in the upper surface of permafrost, are maintained by flow of heat from bodies of surface water into subjacent alluvium and bedrock. Brackish or saline ground water occurs in bedrock beneath as much as 1,055 feet of permafrost in the Arctic foothills and beneath 750 to 800 feet of permafrost beneath low terraces of the Colville River valley. The foothill area is unfavorable for developing supplies of potable ground water because of the great depth to water, predominance of brackish or saline water, and low potential yield of the bedrock. In the Colville River valley, shallow unfrozen alluvium beneath the river and deep lakes will yield abundant year-round supplies of ground water, but the bedrock below permafrost yields less than 10 gpm (gallons per minute) of saline or brackish water.

A stream temperature model for the Peace-Athabasca River basin

NASA Astrophysics Data System (ADS)

Morales-Marin, L. A.; Rokaya, P.; Wheater, H. S.; Lindenschmidt, K. E.

2017-12-01

Water temperature plays a fundamental role in water ecosystem functioning. Because it regulates flow energy and metabolic rates in organism productivity over a broad spectrum of space and time scales, water temperature constitutes an important indicator of aquatic ecosystems health. In cold region basins, stream water temperature modelling is also fundamental to predict ice freeze-up and break-up events in order to improve flood management. Multiple model approaches such as linear and multivariable regression methods, neural network and thermal energy budged models have been developed and implemented to simulate stream water temperature. Most of these models have been applied to specific stream reaches and trained using observed data, but very little has been done to simulate water temperature in large catchment river networks. We present the coupling of RBM model, a semi-Lagrangian water temperature model for advection-dominated river system, and MESH, a semi-distributed hydrological model, to simulate stream water temperature in river catchments. The coupled models are implemented in the Peace-Athabasca River basin in order to analyze the variation in stream temperature regimes under changing hydrological and meteorological conditions. Uncertainty of stream temperature simulations is also assessed in order to determine the degree of reliability of the estimates.

Interior River Lowland Ecoregion Summary Report

USGS Publications Warehouse

Karstensen, Krista A.

2008-01-01

ECOREGION DESCRIPTION The Interior River Lowlands ecoregion encompasses 93,200 square kilometers (km2) across southern and western Illinois, southwest Indiana, east-central Missouri, and fractions of northwest Kentucky and southeast Iowa. The ecoregion includes the confluence areas of the Mississippi, Missouri, Ohio, Illinois, and Wabash Rivers, and their tributaries. This ecoregion was formed in non-resident, non-calcareous sedimentary rock (U.S. Environmental Protection Agency, 2006). The unstratified soil deposits present north of the White River in Indiana are evidence that pre-Wisconsinan ice once covered much of the Interior River Lowlands. The geomorphic characteristics of this area also include terraced valleys filled with alluvium as well as outwash, acolian, and lacustrine deposits. Historically, agricultural land use has been a vital economic resource for this region. The drained alluvial soils are farmed for feed grains and soybeans, whereas the valley uplands also are used for forage crops, pasture, woodlots, mixed farming, and livestock (USEPA, 2006). This ecoregion provides a key component of national energy resources as it contains the second largest coal reserve in the United States, and the largest reserve of bituminous coal (Varanka and Shaver, 2007). One of the primary reasons for change in the ecoregion is urbanization.

Ice Harbor Spillway Dissolved Gas Field Studies: Before and After Spillway Deflectors

DTIC Science & Technology

2016-07-01

Executive Summary The operation of spillways on the Columbia and Snake Rivers causes the absorption of atmospheric gases (chiefly nitrogen and oxygen) to...chiefly nitrogen and oxygen) to super- saturated levels. For many operations, the total dissolved gas (TDG) levels exceed state and National...powerhouse releases. However, these mass- balance calculations conclusively show that a substantial portion of the powerhouse discharge becomes entrained

Detroit and the Lower Peninsula of Michigan

NASA Technical Reports Server (NTRS)

1973-01-01

This scene displays the southeastern part of Michigan's Lower Peninsula and adjacent Ontario, Canada (43.0N, 84.0W). Detroit can be recognized by its radial pattern of development and sediment plumes in the rivers from the massive industrial activity. The area pockmarked by lakes northwest of Detroit essentially outlines the limits of the Defiance Moraine caused by the stagnation and melting of Ice Age glaciers.

The Response of Tundra to Biophysical Changes Ten Years Following the Anaktuvuk River Fire, Arctic Foothills, Alaska.

NASA Astrophysics Data System (ADS)

Jones, B. M.; Miller, E. A.; Jandt, R.; Baughman, C. A.

2017-12-01

Ten years following a large and severe wildfire in the arctic foothills of the Brooks Range, Alaska, tundra is experiencing rapid biophysical changes. Plant communities are responding to primary disturbance by fire but also to ground-ice melt, terrain subsidence, and apparent increase in soil drainage or evapotranspiration.The Anaktuvuk River Fire burned about 104,000 ha in 2007, spreading over broad ranges in soils, topography, hydrography, and permafrost features. Fourteen marked transects were measured between 2008-2011 and again in 2017 for cover of ground-layer vegetation, tall shrub abundance, thaw depth, and soil properties. A complementary set of 11 reference transects surrounding the burn was also sampled.We observed much higher rates of thermokarst inside the burn than out. Even low severity burn areas experienced noticeable thaw subsidence. Mean annual ground temperature at 1 m depth has warmed 1.5°C relative to unburned tundra. In cases ice wedge troughs have deepened by more than 1 m in areas underlain by yedoma soils. Troughs were characterized by cracking soil and slumping tussocks, often into ponded water. Troughs and degraded ice features appear to be draining adjacent polygon centers leading to a general drying of the tundra. Tussockgrasses inside the burn continue to grow and flower vigorously, suggesting a continued flush of soil nutrients. Post-fire accumulation of organic material is generally <5 cm of mostly moss and plant litter. Species of tall willow are responding by increases in stature and colonization of thermokarst areas.Other studies suggest that tundra north of the Brooks Range is responding to climate change with widespread expansion of and dominance by tall shrubs. Our observations from the Anaktuvuk River Burn, as well as at several other older burns, suggest that fire greatly accelerates this succession. Records and observations suggest that lightning and ignitions are becoming more frequent north of the Brooks Range.Our monitoring of this burn over the last ten years reveals a story much more complicated than our team can tell, inviting involvement of other disciplines, particularly hydrology, soil and landform science, remote sensing, and wildlife and subsistence resource management.

Glacier meltwater flow paths and storage in a geomorphologically complex glacial foreland: The case of the Tapado glacier, dry Andes of Chile (30°S)

NASA Astrophysics Data System (ADS)

Pourrier, J.; Jourde, H.; Kinnard, C.; Gascoin, S.; Monnier, S.

2014-11-01

The Tapado catchment is located in the upper Elqui river basin (4000-5550 m) in northern Chile. It comprises the Tapado glacial complex, which is an assemblage of the Tapado glacier and the glacial foreland (debris-covered glacier, rock glacier, and moraines). Although the hydrological functioning of this catchment is poorly known, it is assumed to actively supply water to the lower semi-arid areas of the Elqui river basin. To improve our knowledge of the interactions and water transfers between the cryospheric compartment (glacier, debris-covered glacier, and rock glacier) and the hydrological compartment (aquifers, streams), the results of monitoring of meteorological conditions, as well as discharge, conductivity and temperature of streams and springs located in the Tapado catchment were analyzed. The hydrological results are compared to results inferred from a ground penetrating radar (GPR) survey of the underground structure of the glacial foreland. Water production from the Tapado glacier was shown to be highly correlated with daily and monthly weather conditions, particularly solar radiation and temperature. The resulting daily and monthly streamflow cycles were buffered by the glacial foreland, where underground transfers took place through complex flow paths. However, the development of a thermokarst drainage network in a portion of the glacial foreland enabled rapid concentrated water transfers that reduced the buffer effect. The glacial foreland was shown to act as a reservoir, storing water during high melt periods and supplying water to downstream compartments during low melt periods. GPR observations revealed the heterogeneity of the internal structure of the glacial foreland, which is composed of a mixture of ice and rock debris mixture, with variable spatial ice content, including massive ice lenses. This heterogeneity may explain the abovementioned hydrological behaviors. Finally, calculation of a partial hydrological budget confirmed the importance of the Tapado catchment in supplying water to lower areas of the Elqui river basin. Water production from, and transfer through, cryospheric compartments, and its subsequent interactions with hydrological compartments are key processes driving the summer water supply from the Tapado catchment.

Fecal indicator bacteria persistence under natural conditions in an ice-covered river.

PubMed Central

Davenport, C V; Sparrow, E B; Gordon, R C

1976-01-01

Total coliform (TC), fecal coliform (FC), and fecal streptococcus (FS) survival characteristics, under natural conditions at 0 degrees C in an ice-covered river, were examined during February and March 1975. The membrane filter (MF) technique was used throughout the study, and the multiple-tube (MPN) method was used in parallel on three preselected days for comparative recovery of these bacteria. Survival was studied at seven sample stations downstream from all domestic pollution sources in a 317-km reach of the river having 7.1 days mean flow time (range of 6.0 to 9.1 days). The mean indicator bacteria densities decreased continuously at successive stations in this reach and, after adjustment for dilution, the most rapid die-off was found to occur during the first 1.9 days, followed by a slower decrease. After 7.1 days, the relative survival was TC less than FC less than FS, with 8.4%, 15.7%, and 32.8% of the initial populations remaining viable, respectively. These rates are higher than previously reported and suggest that the highest survival rates for these bacteria in receiving streams can be expected at 0 degree C under ice cover. Additionally, the FC-FS ratio was greater than 5 at all stations, indicating that this ratio may be useable for determining the source of fecal pollution in receiving streams for greater than 7 days flow time at low water temperatures. The MPN and MF methods gave comparable results for the TC and FS at all seven sample stations, with both the direct and verified MF counts within the 95% confidence limits of the respective MPNs in most samples, but generally lower than the MPN index. Although FC recovery on membrane filters was comparable results at stations near the pollution source. However, the results became more comparable with increasing flow time. The results of this study indicate that heat shock is a major factor in suppression of the FC counts on the membrane filters at 44.5 degree C. Heat shock may be minimized by extended incubation at 35 degrees C before exposure to the higher temperature. PMID:825042

20 years of mass balances on the Piloto glacier, Las Cuevas river basin, Mendoza, Argentina

NASA Astrophysics Data System (ADS)

Leiva, J. C.; Cabrera, G. A.; Lenzano, L. E.

2007-10-01

Climatic changes of the 20th century have altered the water cycle in the Andean basins of central Argentina. The most visible change is seen in the mountain glaciers, with loss of part of their mass due to decreasing thickness and a substantial recession in the last 100 years. This paper briefly describes the results of glacier mass balance research since 1979 in the Piloto Glacier at the Cajón del Rubio, in the headwaters of Las Cuevas River, presenting new results for the period 1997-2003. Very large interannual variability of net annual specific balance is evident, due largely to variations in winter snow accumulation, with a maximum net annual value of + 151 cm w.e. and a minimum value of - 230 cm w.e. Wet El Niño years are normally associated with positive net annual balances, while dry La Niña years generally result in negative balances. Within the 24-year period, 67% of the years show negative net annual specific balances, with a cumulative mass balance loss of - 10.50 m water equivalent (w.e.). Except for exceptions normally related to El Niño events, a general decreasing trend of winter snow accumulation is evident in the record, particularly after 1992, which has a strong effect in the overall negative mass balance values. The glacier contribution to Las Cuevas River runoff is analysed based on the Punta de Vacas River gauge station for a hypothetical year without snow precipitation (YWSP), when the snowmelt component is zero. Extremely dry years similar to a YWSP have occurred in 1968-1969, 1969-1970 and 1996-1997. The Punta de Vacas gauge station is located 62 km downstream from Piloto Glacier, and the basin contains 3.0% of uncovered glacier ice and 3.7% of debris-covered ice. The total glacier contribution to Las Cuevas River discharge is calculated as 82 ± 8% during extremely dry years. If glacier wastage continues at the present trend as observed during the last 2 decades, it will severely affect the water resources in the arid central Andes of Argentina.

Recognition and characterization of networks of water bodies in the Arctic ice-wedge polygonal tundra using high-resolution satellite imagery

NASA Astrophysics Data System (ADS)

Skurikhin, A. N.; Gangodagamage, C.; Rowland, J. C.; Wilson, C. J.

2013-12-01

Arctic lowland landscapes underlain by permafrost are often characterized by polygon-like patterns such as ice-wedge polygons outlined by networks of ice wedges and complemented with polygon rims, troughs, shallow ponds and thermokarst lakes. Polygonal patterns and corresponding features are relatively easy to recognize in high spatial resolution satellite imagery by a human, but their automated recognition is challenging due to the variability in their spectral appearance, the irregularity of individual trough spacing and orientation within the patterns, and a lack of unique spectral response attributable to troughs with widths commonly between 1 m and 2 m. Accurate identification of fine scale elements of ice-wedge polygonal tundra is important as their imprecise recognition may bias estimates of water, heat and carbon fluxes in large-scale climate models. Our focus is on the problem of identification of Arctic polygonal tundra fine-scale landscape elements (as small as 1 m - 2 m width). The challenge of the considered problem is that while large water bodies (e.g. lakes and rivers) can be recognized based on spectral response, reliable recognition of troughs is more difficult. Troughs do not have unique spectral signature, their appearance is noisy (edges are not strong), their width is small, and they often form connected networks with ponds and lakes, and thus they have overlapping spectral response with other water bodies and surrounding non-water bodies. We present a semi-automated approach to identify and classify Arctic polygonal tundra landscape components across the range of spatial scales, such as troughs, ponds, river- and lake-like objects, using high spatial resolution satellite imagery. The novelty of the approach lies in: (1) the combined use of segmentation and shape-based classification to identify a broad range of water bodies, including troughs, and (2) the use of high-resolution WorldView-2 satellite imagery (with resolution of 0.6 m) for this identification. The approach starts by segmenting water bodies from an image, which are then categorized using shape-based classification. Segmentation uses combination of pan sharpened multispectral bands and is based on the active contours without edges technique. The segmentation is robust to noise and can detect objects with weak boundaries that is important for extraction of troughs. We then categorize the segmented regions via shape based classification. Because segmentation accuracy is the main factor impacting the quality of the shape-based classification, for segmentation accuracy assessment we created reference image using WorldView-2 satellite image of ice-wedge polygonal tundra. Reference image contained manually labelled image regions which cover components of drainage networks, such as troughs, ponds, rivers and lakes. The evaluation has shown that the approach provides a good accuracy of segmentation and reasonable classification results. The overall accuracy of the segmentation is approximately 95%, the segmentation user's and producer's accuracies are approximately 92% and 97% respectively.

Preliminary Results of the Permafrost Carbon Study in the Lower Kolyma Lowland (Eastern Siberia) Based on Drilling Record

NASA Astrophysics Data System (ADS)

Spektor, V. V.; Kholodov, A. L.; Bulygina, E. B.; Andreeva, V.; Broderick, D.; Spawn, S.; Natali, S.; Davydova, A.

2012-12-01

In 2012, the Polaris Project (thepolarisproject.org, Director R.M. Holmes) has conducted the permafrost drilling on the Kolyma Lowland for a complex study of permafrost carbon as a potential source for microbial decomposition. In July 2012, the first two boreholes, 15.1 and 13.4 m in depth, were drilled. The first borehole (BH 12/1) was drilled in the stratum of ice complex (yedoma) on the local watershed near the Schuch'e lake in the vicinity of the town Chersky (N68°44.7' E161°23'). The depth of active layer is 45 cm. The permafrost to the depth of 15.1 m represents grey and brown silts with predominant homogeneous structure. Silts contain numerous thread-like roots, scarce plant macrofossils, and in places are colored with unclear spots of ferrugination. Cryostructure is mainly pore ice or thin lense-like ice layers. Wedge ice is observed in the interval 12.5-12.9 m. The moisture volumetric percentage of silts varies along the stratum, mainly, between 40-50%. The organic content, defined in every 20 cm of the core as a loss on ignition, varies between 2-4%. The second borehole (BH 12/2), located in the Pleistocene Park (N68°30.8' E161°30') was drilled through modern floodplain sediments (0-0.6 m) of the Kolyma River with polygonal network at the surface, underlain by peat (0.6-1.3 m), silt deposits of thermokarst lake (1.3-12.0 m), and river grey sands (12.0-13.4 m). The active layer thickness is 65 cm. The cryostructure is predominantly lattice-like. Silts contain modern wedge ice at the depth of 2.5-2.7 m. Mollusk shells and large amount of plant macrofossils are observed in the interval 5.7-8.0 m. The organic content in the thermokarst deposits varies in average within 2-3 %, but is about 1% in the underlying river sands. To investigate permafrost carbon, samples for microbial and enzyme activities, as well as samples of trapped gases were collected from different horizons of frozen cores. Samples for palynological, diatom, and lithological analyses, as well as for absolute age AMS 14C and isotopes O16/O18, and D were collected for reconstructing paleoclimate and paleogeographic conditions of organic matter accumulation and preservation. As a part of the TSP Program (Thermal State Permafrost), both boreholes were equipped with loggers for temperature measurements at 3,5,10, and 15 m and 3,4,10, and 13 m for the BH 12/1 and 12/2 correspondingly. To evaluate the role of landscape conditions on the thermal regime of permafrost and active layer dynamics terrestrial survey near the boreholes was conducted.

Features caused by ground ice growth and decay in Late Pleistocene fluvial deposits, Paris Basin, France

NASA Astrophysics Data System (ADS)

Bertran, Pascal; Andrieux, Eric; Bateman, Mark; Font, Marianne; Manchuel, Kevin; Sicilia, Deborah

2018-06-01

Last Glacial fluvial sequences in the Paris Basin show laminated lacustrine deposits OSL and radiocarbon dated to between 24.6 and 16.6 ka in one site and overlying alluvial sandy gravel. A thermokarst origin of the lakes is supported by abundant traces of ground ice, particularly ice wedge pseudomorphs beneath the lacustrine layers and synsedimentary deformation caused by thaw settlement. The features include brittle deformation (normal and reverse faults) resulting from ground subsidence owing to ice melting and ductile deformations caused by slumping of the sediments heaved by the growth of ice-cored mounds. These correspond to lithalsas (or lithalsa plateaus) and/or to open system pingos. At least two generations of thermokarst are recorded and may reflect the millennial climate variability typical of the Last Glacial. The structures studied in quarries are associated with an undulating topography visible in 5-m DEMs and a spotted pattern in aerial photographs. The search for similar patterns in the Paris Basin indicates that many other potential thermokarst sites exist in the Last Glacial terrace (Fy) of rivers located north of 48°N when they cross the lower Cretaceous sands and marls. In some sites, the presence of organic-poor, fine-grained deposits presumably of lacustrine origin was confirmed by borehole data. The site distribution coincides broadly with that already known for ice wedge pseudomorphs. This study provides new evidence of permafrost-induced ground deformations in France and strongly suggests that thermokarst played a significant and probably largely underestimated role in the genesis of Late Pleistocene landscapes.

Ice in Caspian Sea and Aral Sea, Kazakhstan

NASA Technical Reports Server (NTRS)

2002-01-01

In this MODIS image from December 3, 2001, winter sea ice can be seen forming in the shallow waters of the northern Caspian (left) and Aral (upper right) Seas. Despite the inflow of the Volga River (upper left), the northern portion of the Caspian Sea averages only 17 ft in depth, and responds to the region's continental climate, which is cold in winter and hot and dry in the summer. The southern part of the Sea is deeper and remains ice-free throughout the winter. The dirty appearance of the ice may be due to sediment in the water, but may also be due to wind-driven dust. The wind in the region can blow at hurricane-force strength and can cause the ice to pile up in hummocks that are anchored to the sea bottom. The eastern portion of the Aral Sea is also beginning to freeze. At least two characteristics of the Aral Sea 'compete' in determining whether its waters will freeze. The Sea is shallow, which increases the likelihood of freezing, but it is also very salty, which means that lower temperatures are required to freeze it than would be required for fresh water. With average December temperatures of 18o F, it's clearly cold enough to allow ice to form. As the waters that feed the Aral Sea continue to be diverted for agriculture, the Sea becomes shallower and the regional climate becomes even more continental. This is because large bodies of water absorb and retain heat, moderating seasonal changes in temperature. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

Transport of particle-associated elements in two agriculture-dominated boreal river systems.

PubMed

Marttila, Hannu; Saarinen, Tuomas; Celebi, Ahmet; Kløve, Bjørn

2013-09-01

Transport of particulate pollutants in fluvial systems can contribute greatly to total loads. Understanding transport mechanics under different hydrological conditions is key in successful load estimation. This study analysed trace elements and physico-chemical parameters in time-integrated suspended sediment samples, together with dissolved and total concentrations of pollutants, along two agriculture- and peatland-dominated boreal river systems. The samples were taken in a spatially and temporally comprehensive sampling programme during the ice-free seasons of 2010 and 2011. The hydrochemistry and transport of particle-bound elements in the rivers were strongly linked to intense land use and acid sulphate soils in the catchment area, with arable, pasture and peat areas in particular being main diffuse sources. There were significant seasonal and temporal variations in dissolved and particulate fluxes, but spatial variations were small. Continuous measurements of EC, turbidity and discharge proved to be an accurate indicator of dissolved and particulate fluxes. Overall, the results show that transport of particle-bound elements makes a major contribution to total transport fluxes in agriculture-dominated boreal rivers. Copyright © 2013 Elsevier B.V. All rights reserved.

Chronologic evidence for multiple periods of loess deposition during the Late Pleistocene in the Missouri and Mississippi River Valley, United States: Implications for the activity of the Laurentide ice sheet

USGS Publications Warehouse

Forman, S.L.; Bettis, E. Arthur; Kemmis, T.J.; Miller, B.B.

1992-01-01

The loess stratigraphy of the mid-continental U.S. is an important proxy record for the activity of the Laurentide Ice Sheet in North America. One of the most outstanding problems is deciphering the age of loess deposits in this area during the late Pleistocene. Radiocarbon dating of snails and thermoluminescence dating of the fine-silt fraction (4-11 ??m) from loess at the Loveland Loess type section, Loveland, Iowa and a recent excavation at the Pleasant Grove School section. Madison County, Illinois provide new chronologic control on loess deposition in the Mississippi/Missouri River Valley chronology indicates that the Loveland Loess is Illinoian in age (135??20 ka) but is not correlative with the Teneriffe Silt which is dated to 77 ?? 8 ka. Concordant radiocarbon and thermoluminescence age estimates demonstrate that the Roxana Silt and a correlative loess in Iowa, the Pisgah Formation, is probably 40-30 ka old. These age estimates in conjunction with previous results indicate that there were four periods of loess deposition during the last 150 ka at 25-12 ka, 45-30 ka, 85-70 ka and at ca. 135 ?? 20 ka. This chronology of loess deposition supports the presence of both a late Illinoian and early Wisconsinan loess and associated soils. Thus, there may be more than one soil in the loess stratigraphy of the mid-continental U.S. with morphologies similar to the Sangamon Soil. The last three periods of loess deposition may be correlative with periods of elevated dust concentrations recorded in the Dye 3 ice core from southern Greenland. This is particularly significant because both areas possibly had the same source for eolian particles. Reconstructions of atmospheric circulation for glacial periods show a southerly deflected jet stream that could have transported dust from the mid-continental USA to southern Greenland. Lastly, the inferred record of loess deposition is parallel to a chronology for deglaciation of the Laurentide Ice Sheet deciphered from chronologic and stratigraphic studies of raised glacial and marine sediments in the Hudson Bay Lowlands, Canada. These chronologies indicate that the Laurentide Ice Sheet was quite dynamic during the late Pleistocene, advancing and retreating across North America at least four times during the last 150 ka. ?? 1992.

Characterising and improving the performance of the Sentinel-3 SRAL altimeter: A Report from SCOOP, SHAPE & SPICE Projects

NASA Astrophysics Data System (ADS)

Restano, Marco; Ambrózio, Américo; Cotton, David; Scoop Team; Fabry, Pierre; Shape Team; McMillan, Malcolm; Spice Team; Benveniste, Jérôme

2017-04-01

Under the ESA Scientific Exploitation of Operational Missions (SEOM) Programme, 3 Projects are currently underway to accurately characterise and improve the performance of the Sentinel-3 SRAL SAR mode altimeter. They are: 1) SCOOP (SAR Altimetry Coastal & Open Ocean Performance Exploitation and Roadmap Study) for Coastal and Open Ocean; 2) SHAPE (Sentinel-3 Hydrologic Altimetry PrototypE) for Inland Water; 3) SPICE (Sentinel-3 Performance improvement for ICE sheets) for Ice Sheets. As projects started before the launch of Sentinel-3 (a full SAR mission), calibrated Cryosat-2 data have been used as input to a processor replicating the Sentinel-3 baseline processing. For the SCOOP project, a first test dataset has been released to end users including data from 10 regions of interest. The successful SAMOSA retracker, adopted in the previous CP4O Project (CryoSat Plus for Oceans), has been readapted to re-track Sentinel-3 waveforms. An improved version of SAMOSA will be released at the end of the project. The SHAPE project is working towards the design and assessment of alternative/innovative techniques not implemented in the Sentinel-3 ground segment (performing no Inland Water dedicated processing). Both rivers and lakes will be studied. Amazon, Brahmaputra and Danube have been selected as rivers, whereas Titicaca and Vanern have been chosen as lakes. The study will include the assimilation of output products into hydrological models for all regions of interest. A final dataset will be provided to end users. The SPICE project is addressing four high level objectives: 1) Assess and improve the Delay-Doppler altimeter processing for ice sheets. 2) Assess and develop SAR waveform retrackers for ice sheets. 3) Evaluate the performance of SAR altimetry relative to conventional pulse limited altimetry. 4) Assess the impact on SAR altimeter measurements of radar wave interaction with the snowpack. Dataset used for validation include ICESat and IceBridge products. Vostok, Dome C and the Spirit Sector (all located in Antarctica) have been selected, along with the Russell Glacier in Greenland, as regions of interest. In the frame of both SCOOP and SHAPE projects, improved wet troposphere corrections will be estimated for all regions of interest.

A physically based model of global freshwater surface temperature

NASA Astrophysics Data System (ADS)

Beek, Ludovicus P. H.; Eikelboom, Tessa; Vliet, Michelle T. H.; Bierkens, Marc F. P.

2012-09-01

Temperature determines a range of physical properties of water and exerts a strong control on surface water biogeochemistry. Thus, in freshwater ecosystems the thermal regime directly affects the geographical distribution of aquatic species through their growth and metabolism and indirectly through their tolerance to parasites and diseases. Models used to predict surface water temperature range between physically based deterministic models and statistical approaches. Here we present the initial results of a physically based deterministic model of global freshwater surface temperature. The model adds a surface water energy balance to river discharge modeled by the global hydrological model PCR-GLOBWB. In addition to advection of energy from direct precipitation, runoff, and lateral exchange along the drainage network, energy is exchanged between the water body and the atmosphere by shortwave and longwave radiation and sensible and latent heat fluxes. Also included are ice formation and its effect on heat storage and river hydraulics. We use the coupled surface water and energy balance model to simulate global freshwater surface temperature at daily time steps with a spatial resolution of 0.5° on a regular grid for the period 1976-2000. We opt to parameterize the model with globally available data and apply it without calibration in order to preserve its physical basis with the outlook of evaluating the effects of atmospheric warming on freshwater surface temperature. We validate our simulation results with daily temperature data from rivers and lakes (U.S. Geological Survey (USGS), limited to the USA) and compare mean monthly temperatures with those recorded in the Global Environment Monitoring System (GEMS) data set. Results show that the model is able to capture the mean monthly surface temperature for the majority of the GEMS stations, while the interannual variability as derived from the USGS and NOAA data was captured reasonably well. Results are poorest for the Arctic rivers because the timing of ice breakup is predicted too late in the year due to the lack of including a mechanical breakup mechanism. Moreover, surface water temperatures for tropical rivers were overestimated, most likely due to an overestimation of rainfall temperature and incoming shortwave radiation. The spatiotemporal variation of water temperature reveals large temperature differences between water and atmosphere for the higher latitudes, while considerable lateral transport of heat can be observed for rivers crossing hydroclimatic zones, such as the Nile, the Mississippi, and the large rivers flowing to the Arctic. Overall, our model results show promise for future projection of global surface freshwater temperature under global change.

The role of glaciers for Swiss hydropower production

NASA Astrophysics Data System (ADS)

Schaefli, Bettina; Manso, Pedro; Fischer, Mauro; Huss, Matthias

2016-04-01

In Switzerland, hydropower represents over 50% of the total annual electricity production. Given the Alpine setting of the country, this hydropower production (HPP) strongly relies on the natural storage of discharge in form of ice and snow over months to decades. The sensitivity of glacier-fed HPP systems with respect to climate change depends on how the today's production and the infrastructure design relies on the seasonal streamflow delay expected from the natural storage effect of snow and ice. For low-head run-of-river HPP plants built on large lowland rivers, the ongoing glacier retreat (resulting in strong summer melt) currently sustains higher flows during summer months, an effect that will certainly be reduced once the glaciers will have reached a critical size. This effect will also modify the inflow to the large storage HPP plants that have been designed to shift large amounts of meltwater inflows from summer to winter. The management of these reservoirs will certainly have to be adapted to future inflow patterns. An interesting case are high-head run-of-river plants (with heads from 100 to 1100 m) that short-circuit a given river reach. Future regime shifts with less sustained summer flow and more concentrated spring melt flows might critically reduce the annual production due to intake overflow during spring and reduced flow during summer. In this work, we discuss the role of glaciers for these different HPP types in detail, including an overview of how glacier retreat might influence their production. This comprehensive study synthesizes up-to-date estimations of glacier mass change since the 1980s and its influence on high Alpine discharge regimes and state-of-the art simulations of potential future glacier discharge regimes. We also attempt an extrapolation to the country level based on a hydropower GIS database that has been developed for economic purposes. Ongoing Swiss research on sediment production and management might complete this picture with the role of glacier sediment delivery for hydropower operation.

Continuous water-quality monitoring and regression analysis to estimate constituent concentrations and loads in the Sheyenne River, North Dakota, 1980-2006

USGS Publications Warehouse

Ryberg, Karen R.

2007-01-01

This report presents the results of a study by the U.S. Geological Survey, done in cooperation with the North Dakota State Water Commission, to estimate water-quality constituent concentrations at seven sites on the Sheyenne River, N. Dak. Regression analysis of water-quality data collected in 1980-2006 was used to estimate concentrations for hardness, dissolved solids, calcium, magnesium, sodium, and sulfate. The explanatory variables examined for the regression relations were continuously monitored streamflow, specific conductance, and water temperature. For the conditions observed in 1980-2006, streamflow was a significant explanatory variable for some constituents. Specific conductance was a significant explanatory variable for all of the constituents, and water temperature was not a statistically significant explanatory variable for any of the constituents in this study. The regression relations were evaluated using common measures of variability, including R2, the proportion of variability in the estimated constituent concentration explained by the explanatory variables and regression equation. R2 values ranged from 0.784 for calcium to 0.997 for dissolved solids. The regression relations also were evaluated by calculating the median relative percentage difference (RPD) between measured constituent concentration and the constituent concentration estimated by the regression equations. Median RPDs ranged from 1.7 for dissolved solids to 11.5 for sulfate. The regression relations also may be used to estimate daily constituent loads. The relations should be monitored for change over time, especially at sites 2 and 3 which have a short period of record. In addition, caution should be used when the Sheyenne River is affected by ice or when upstream sites are affected by isolated storm runoff. Almost all of the outliers and highly influential samples removed from the analysis were made during periods when the Sheyenne River might be affected by ice.

Synoptical situations and meteorological conditions associated to floods in the mouth of rivers in the European part of Russia

NASA Astrophysics Data System (ADS)

Matveeva, Tatiana; Gushchina, Daria

2013-04-01

The synoptical situations associated to the various type of floods in the mouth of rivers in European part of Russia are described. The storm surges, water flows and ice-jams are considered for Baltic, Barents sea, White sea, Azov sea, Black sea and Caspian sea regions. It is shown that the specific types of flood may be associated to various synoptical situations. Therefore it is unlikely to introduce the classification of synoptical regimes resulting in specific type of floods. However for each zone under consideration and for each specific flood type it is possible to determine the potential predictors of inundation: i.e. meteorological parameters which are characteristics of all cases of specific flood. There are: • for storm surges - long term wind forcing resulting in seiches in the sea, strong wind speed (the threshold varies in dependence on region), the wind direction orthogonal to the flow of river and strong baric gradient; • for water flows - the abundant precipitation, usually associate with the intensive frontal zone, the sudden change of air temperature resulting in snow melting in spring time; • for ice-jams - the strong temperature gradient extended in north-south direction resulting in negative temperature in the river mouth and positive temperature in the other basin. The probability of occurrence of predictors mentioned above was estimated for modern climate and global warming conditions using the outputs of ECHAM5/MPI-OM model. It is shown that the occurrence of intensive frontal zone and rainfall in the South of Russia will increase (decrease) in summer (winter) under warmer climate conditions which may contribute to the increase of water flows in this region. Maximum of floods occurs during the warm period, we can conclude that global warming increases the risk of floods in Black Sea coast.

Hydro-glaciological modeling in the Upper Maipo River basin, extratropical Andes Cordillera, with explicit representation of debris-covered glaciers.

NASA Astrophysics Data System (ADS)

McPhee, J. P.; Castillo, Y.; Escobar, M.; Pellicciotti, F.

2014-12-01

In this work we improve and calibrate a hydro-glaciological model based on a simplified energy balance approach using the WEAP modeling platform for two catchments in the headwaters of the Maipo River Basin, in the Andes Mountains of Central Chile. The Morales Creek catchment includes the San Francisco glacier, a clean glacier occupying 7% of the catchment area. The Pirámide catchment holds the debris-covered Pirámide Glacier, which covers 20% of the catchment area. Detailed field measurements have been carried out on both glaciers to characterize their melt and meteorological regimes. We calibrate an Enhanced Temperature Index melt model against ablation stakes and runoff measurements, and obtain clear differences between the optimal parameters for the clean and debris-covered glaciers. Calibrate melt threshold temperatures are 0,25 and 0,5ºC for the clean and debris-covered glaciers, respectively, while the fraction of net shortwave radiation employed for melting is 90 and 83% for clean and debris-covered glaciers, respectively. These results are coherent with an insulating effect of the debris cover at the Pirámide glacier. The hydrologic contribution of ice melt for the clean, San Francisco glacier is equivalent to 32% of total runoff measured at the Morales Creek outlet during the simulation period; on the other hand, ice melt accounts for 83% of total runoff estimated at the outlet of the Pirámide catchment over the same period. These results are part on an ongoing effort aimed at quantifying cryospheric contribution to the hydrology of the Maipo River basin, one of the key river basins in Chile, on the face of accelerated climate change, and is the first documented work to explicitly include debris-covered glaciers in a context of basin-wide hydrological modeling.

Organic carbon in glacial fjords of Chilean Patagonia

NASA Astrophysics Data System (ADS)

Pantoja, Silvio; Gutiérrez, Marcelo; Tapia, Fabián; Abarzúa, Leslie; Daneri, Giovanni; Reid, Brian; Díez, Beatriz

2016-04-01

The Southern Ice Field in Chilean Patagonia is the largest (13,000 km2) temperate ice mass in the Southern hemisphere, yearly transporting ca. 40 km3 of freshwater to fjords. This volume of fresh and cold water likely affects adjacent marine ecosystems by changing circulation, productivity, food web dynamics, and the abundance and distribution of planktonic and benthic organisms. We hypothesize that freshwater-driven availability of inorganic nutrient and transport of organic and inorganic suspended matter, as well as microbes, become a controlling factor for productivity in the fjord associated with the Baker river and Jorge Montt glacier. Both appear to be sources of silicic acid, but not of nitrate and particulate organic carbon, especially during summer, when surface PAR and glacier thawing are maximal. In contrast to Baker River, the Jorge Montt glacier is also a source of dissolved organic carbon towards a proglacial fjord and the Baker Channel, indicating that a thorough chemical description of sources (tidewater glacier and glacial river) is needed. Nitrate in fiord waters reaches ca. 15 μM at 25 m depth with no evidence of mixing up during summer. Stable isotope composition of particulate organic nitrogen reaches values as low as 3 per mil in low-salinity waters near both glacier and river. Nitrogen fixation could be depleting δ15N in organic matter, as suggested by the detection at surface waters of nif H genes belonging to diazotrophs near the Montt glacier. As diazotrophs have also been detected in other cold marine waters (e.g. Baltic Sea, Arctic Ocean) as well as glaciers and polar terrestrial waters, there is certainly a potential for both marine and freshwater microbes to contribute and have a significant impact on the Patagonian N and C budgets. Assessing the impact of freshwater on C and N fluxes and the microbial community structure in Patagonian waters will allow understanding future scenarios of rapid glacier melting. This research was funded by COPAS Sur-Austral (PFB-31).

Synoptic evaluation of carbon cycling in Beaufort Sea during summer: contrasting river inputs, ecosystem metabolism and air-sea CO2 fluxes

NASA Astrophysics Data System (ADS)

Forest, A.; Coupel, P.; Else, B.; Nahavandian, S.; Lansard, B.; Raimbault, P.; Papakyriakou, T.; Gratton, Y.; Fortier, L.; Tremblay, J.-É.; Babin, M.

2013-10-01

The accelerated decline in Arctic sea ice combined with an ongoing trend toward a more dynamic atmosphere is modifying carbon cycling in the Arctic Ocean. A critical issue is to understand how net community production (NCP; the balance between gross primary production and community respiration) responds to changes and modulates air-sea CO2 fluxes. Using data collected as part of the ArcticNet-Malina 2009 expedition in southeastern Beaufort Sea (Arctic Ocean), we synthesize information on sea ice, wind, river, water column properties, metabolism of the planktonic food web, organic carbon fluxes and pools, as well as air-sea CO2 exchange, with the aim of identifying indices of ecosystem response to environmental changes. Data were analyzed to develop a non-steady-state carbon budget and an assessment of NCP against air-sea CO2 fluxes. The mean atmospheric forcing was a mild upwelling-favorable wind (~5 km h-1) blowing from the N-E and a decaying ice cover (<80% concentration) was observed beyond the shelf, the latter being fully exposed to the atmosphere. We detected some areas where the surface mixed layer was net autotrophic owing to high rates of primary production (PP), but the ecosystem was overall net heterotrophic. The region acted nonetheless as a sink for atmospheric CO2 with a mean uptake rate of -2.0 ± 3.3 mmol C m-2d-1. We attribute this discrepancy to: (1) elevated PP rates (>600 mg C m-2d-1) over the shelf prior to our survey, (2) freshwater dilution by river runoff and ice melt, and (3) the presence of cold surface waters offshore. Only the Mackenzie River delta and localized shelf areas directly affected by upwelling were identified as substantial sources of CO2 to the atmosphere (>10mmol C m-2d-1). Although generally <100 mg C m-2d-1, daily PP rates cumulated to a total PP of ~437.6 × 103 t C, which was roughly twice higher than the organic carbon delivery by river inputs (~241.2 × 103 t C). Subsurface PP represented 37.4% of total PP for the whole area and as much as ~72.0% seaward of the shelf break. In the upper 100 m, bacteria dominated (54%) total community respiration (~250 mg C m-2d-1), whereas protozoans, metazoans, and benthos, contributed to 24%, 10%, and 12%, respectively. The range of production-to-biomass ratios of bacteria was wide (1-27% d-1), while we estimated a narrower range for protozoans (6-11% d-1) and metazoans (1-3 % d-1). Over the shelf, benthic biomass was twice higher (~5.9 g C m-2) than the biomass of pelagic heterotrophs (~2.4 g C m-2), in accord with high vertical carbon fluxes on the shelf (956 ± 129 mg C m-2d-1). Threshold PP (PP at which NCP becomes positive) in the surface layer oscillated from 20-152 mg C m-2d-1, with a pattern from low-to-high values as the distance from the Mackenzie River decreased. We conclude that: (1) climate change is exacerbating the already extreme biological gradient across the Arctic shelf-basin system; (2) the Mackenzie Shelf acts as a weak sink for atmospheric CO2, implying that PP exceeds the respiration of terrigenous and marine organic matter in the surface layer; and (3) shelf break upwelling can transfer CO2 to the atmosphere, but massive outgassing can be attenuated if nutrients brought also by upwelling support diatom production. Our study underscores that cross-shelf exchange of waters, nutrients and particles is a key mechanism that needs to be properly monitored as the Arctic transits to a new state.

Synoptic evaluation of carbon cycling in the Beaufort Sea during summer: contrasting river inputs, ecosystem metabolism and air-sea CO2 fluxes

NASA Astrophysics Data System (ADS)

Forest, A.; Coupel, P.; Else, B.; Nahavandian, S.; Lansard, B.; Raimbault, P.; Papakyriakou, T.; Gratton, Y.; Fortier, L.; Tremblay, J.-É.; Babin, M.

2014-05-01

The accelerated decline in Arctic sea ice and an ongoing trend toward more energetic atmospheric and oceanic forcings are modifying carbon cycling in the Arctic Ocean. A critical issue is to understand how net community production (NCP; the balance between gross primary production and community respiration) responds to changes and modulates air-sea CO2 fluxes. Using data collected as part of the ArcticNet-Malina 2009 expedition in the southeastern Beaufort Sea (Arctic Ocean), we synthesize information on sea ice, wind, river, water column properties, metabolism of the planktonic food web, organic carbon fluxes and pools, as well as air-sea CO2 exchange, with the aim of documenting the ecosystem response to environmental changes. Data were analyzed to develop a non-steady-state carbon budget and an assessment of NCP against air-sea CO2 fluxes. During the field campaign, the mean wind field was a mild upwelling-favorable wind (~ 5 km h-1) from the NE. A decaying ice cover (< 80% concentration) was observed beyond the shelf, the latter being fully exposed to the atmosphere. We detected some areas where the surface mixed layer was net autotrophic owing to high rates of primary production (PP), but the ecosystem was overall net heterotrophic. The region acted nonetheless as a sink for atmospheric CO2, with an uptake rate of -2.0 ± 3.3 mmol C m-2 d-1 (mean ± standard deviation associated with spatial variability). We attribute this discrepancy to (1) elevated PP rates (> 600 mg C m-2 d-1) over the shelf prior to our survey, (2) freshwater dilution by river runoff and ice melt, and (3) the presence of cold surface waters offshore. Only the Mackenzie River delta and localized shelf areas directly affected by upwelling were identified as substantial sources of CO2 to the atmosphere (> 10 mmol C m-2 d-1). Daily PP rates were generally < 100 mg C m-2 d-1 and cumulated to a total PP of ~ 437.6 × 103 t C for the region over a 35-day period. This amount was about twice the organic carbon delivery by river inputs (~ 241.2 × 103 t C). Subsurface PP represented 37.4% of total PP for the whole area and as much as ~ 72.0% seaward of the shelf break. In the upper 100 m, bacteria dominated (54%) total community respiration (~ 250 mg C m-2 d-1), whereas protozoans, metazoans, and benthos, contributed to 24, 10, and 12%, respectively. The range of production-to-biomass ratios of bacteria was wide (1-27% d-1), while we estimated a narrower range for protozoans (6-11% d-1) and metazoans (1-3% d-1). Over the shelf, benthic biomass was twofold (~ 5.9 g C m-2) the biomass of pelagic heterotrophs (~ 2.4 g C m-2), in accord with high vertical carbon fluxes on the shelf (956 ± 129 mg C m-2 d-1). Threshold PP (PP at which NCP becomes positive) in the surface layer oscillated from 20 to 152 mg C m-2 d-1, with a pattern from low-to-high values as the distance from the Mackenzie River decreased. We conclude that (1) climate change is exacerbating the already extreme biological gradient across the Beaufort shelf-basin system; (2) the Mackenzie Shelf acts as a weak sink for atmospheric CO2, suggesting that PP might exceed the respiration of terrigenous and marine organic matter in the surface layer; and (3) shelf break upwelling can transfer CO2 to the atmosphere, but CO2 outgassing can be attenuated if nutrients brought also by upwelling support diatom production. Our study underscores that cross-shelf exchange of waters, nutrients and particles is a key mechanism that needs to be properly monitored as the Arctic transits to a new state.

1500 Years of Annual Climate and Environmental Variability as Recorded in Bona-Churchill (Alaska) Ice Cores

NASA Astrophysics Data System (ADS)

Thompson, L. G.; Mosley-Thompson, E. S.; Zagorodnov, V.; Davis, M. E.; Mashiotta, T. A.; Lin, P.

2004-12-01

In 2003, six ice cores measuring 10.5, 11.5, 11.8, 12.4, 114 and 460 meters were recovered from the col between Mount Bona and Mount Churchill (61° 24'N; 141° 42'W; 4420 m asl). These cores have been analyzed for stable isotopic ratios, insoluble dust content and concentrations of major chemical species. Total Beta radioactivity was measured in the upper sections. The 460-meter core, extending to bedrock, captured the entire depositional record at this site where ice temperatures ranged from -24° C at 10 meters to -19.8° C at the ice/bedrock contact. The shallow cores allow assessment of surface processes under modern meteorological conditions while the deep core offers a ˜1500-year climate and environmental perspective. The average annual net balance is ˜~1000 mm of water equivalent and distinct annual signals in dust and calcium concentrations along with δ 18O allow annual resolution over most of the core. The excess sulfate record reflects many known large volcanic eruptions such as Katmai, Krakatau, Tambora, and Laki which allow validation of the time scale in the upper part of the core. The lower part of the core yields a history of earlier volcanic events. The 460-m Bona-Churchill ice core provides a detailed history of the `Little Ice Age' and medieval warm periods for southeastern Alaska. The source of the White River Ash will be discussed in light of the evidence from this core. The 460-m core also provides a long-term history of the dust fall that originates in north-central China. The annual ice core-derived climate records from southeastern Alaska will facilitate an investigation of the likelihood that the high resolution 1500-year record from the tropical Quelccaya Ice Cap (Peru) preserves a history of the variability of both the PDO and the Aleutian Low.

An ice core record of net snow accumulation and seasonal snow chemistry at Mt. Waddington, southwest British Columbia, Canada

NASA Astrophysics Data System (ADS)

Neff, P. D.; Steig, E. J.; Clark, D. H.; McConnell, J. R.; Pettit, E. C.; Menounos, B.

2011-12-01

We recovered a 141 m ice core from Combatant Col (51.39°N, 125.22°W, 3000 m asl) on the flank of Mt. Waddington, southern Coast Mountains, British Columbia, Canada. Aerosols and other impurities in the ice show unambiguous seasonal variations, allowing for annual dating of the core. Clustered melt layers, originating from summer surface heating, also aid in the dating of the core. Seasonality in water stable isotopes is preserved throughout the record, showing little evidence of diffusion at depth, and serves as an independent verification of the timescale. The annual signal of deuterium excess is especially well preserved. The record of lead deposition in the core agrees with those of ice cores from Mt. Logan and from Greenland, with a sharp drop-off in concentration in the 1970s and early 1980s, further validating the timescales. Despite significant summertime melt at this mid-latitude site, these data collectively reveal a continuous and annually resolved 36-year record of snow accumulation. We derived an accumulation time series from the Mt. Waddington ice core, after correcting for ice flow. Years of anomalously high or low snow accumulation in the core correspond with extremes in precipitation data and geopotential height anomalies from reanalysis data that make physical sense. Specifically, anomalously high accumulation years at Mt. Waddington correlate with years where "Pineapple Express" atmospheric river events bring large amounts of moisture from the tropical Pacific to western North America. The Mt. Waddington accumulation record thus reflects regional-scale climate. These results demonstrate the potential of ice core records from temperate glaciers to provide meaningful paleoclimate information. A longer core to bedrock (250-300 m) at the Mt. Waddington site could yield ice with an age of several hundred to 1000 years.

The ICESat-2 Mission: Concept, Pre-Launch Activities, and Opportunities

NASA Technical Reports Server (NTRS)

Markus, Thorsten; Neumann, Tom; Csatho, Beata M.

2011-01-01

Ice sheet and sea level changes have been explicitly identified as a priority in the President's Climate Change Science Program, the Arctic Climate Impact Assessment, the 4th Assessment Report of the IPee and other national and international policy documents. Following recommendations from the National Research Council for an ICESat follow-on mission, the ICESat-2 mission is now under development for launch in early 2016. The primary aims of the ICESat-2 mission are to continue measurements of sea-ice thickness change, and ice sheet elevation changes at scales from outlet glaciers to the entire ice sheet as established by ICES at. In contrast to ICES at, ICESat-2 will employ a 6-beam micro-pulse laser photon-counting approach. The current concept uses a high repetition rate (10 kHz; equivalent to 70 cm on the ground) low-power laser in conjunction with single-photon sensitive detectors to measure range using approximately 532nm (green) light. The concept will enable the generation of seasonal maps of ice sheet elevation of Greenland and Antarctica, monthly maps of sea ice thickness of the polar ocean, a dense map of land elevation (2 km track spacing at the equator after two years) enabling the determination of canopy height, as well as ocean heights. While the mission has been optimized for cryospheric science and vast amount of high precision elevation measurements taken over land and over the ocean as well as of the atmosphere will provide scientists with a wealth of opportunities to explore the utility of ICESat-2. Those will range from the retrieval of cloud properties, to river stages, to snow cover, to land use changes and more. The presentation will review the measurement concept and physical principles of ICESat-2, current and planned activities to assess instrument performance and develop geophysical algorithms, as well as potential opportunities outside the main objectives of ICESat-2.

Contributions to Jarvis Creek Watershed, Alaska, from Winter Accumulation and Glacier Melt Inferred Through Airborne and Ground-Penetrating Radar

NASA Astrophysics Data System (ADS)

Campbell, S. W.; Liljedahl, A. K.; Douglas, T. A.; Bernsen, S.; Gatesman, T.; Gerbi, C. C.

2017-12-01

Glacier meltwater contributions to river discharge has been increasing in much of the Arctic, likely because of higher air temperatures. For small glaciers that provide a large portion of meltwater to downstream discharge, a sustained negative mass balance is concerning to surrounding ecosystems because the water budget will ultimately decline when glacier ice disappears. Separating components of the hydrological budget is important for predicting future discharge, particularly when major inputs such as glacier ice melt are at risk of total loss. Jarvis Glacier in Eastern Alaska offers an example of this potential scenario. It is a 6-km long glacier that has been in retreat since the 1950's, yet it accounts for 15% of the annual downstream discharge into Jarvis Creek (Liljedahl et al., 2017). In March 2012 through April 2017 we completed yearly airborne and ground-penetrating radar surveys over Jarvis Glacier and its surrounding non-glaciated watershed. These surveys were conducted to assess winter snow accumulation and its potential contribution to the hydrological budget of Jarvis Creek. We also surveyed glacier ice thicknesses to estimate ice volume and potential long term future meltwater contributions to Jarvis Creek based on its sustained negative mass balance. High-frequency radar collected across Jarvis Glacier reveal winter accumulation rates between 1.1-1.9 m SWE. Thickness of winter snow in the surrounding glacier-free valleys is highly variable but it tended to accumulate as drifts near ridge tops or low in the valleys. Low-frequency GPR reveals ice thickness reaching 250 m, mid-glacier, tapering to less than 100 m near the debris-rich terminus. Several over-deepened basins exist and an obvious polythermal structure with 20-30 m of cold ice overlaying temperate ice is also evident. Our presentation will summarize further details of these results in relation to current and potential future contributions of glacier ice and winter snowpack melt to Jarvis Creek watershed.

The Contribution to High Asia Runoff from Ice and Snow (CHARIS): Understanding the source and trends of cryospheric contributions to the water balance

NASA Astrophysics Data System (ADS)

Rittger, K.; Armstrong, R. L.; Bair, N.; Racoviteanu, A.; Brodzik, M. J.; Hill, A. F.; Wilson, A. M.; Khan, A. L.; Ramage, J. M.; Khalsa, S. J. S.; Barrett, A. P.; Raup, B. H.; Painter, T. H.

2017-12-01

The Contribution to High Asia Runoff from Ice and Snow, or CHARIS, project is systematically assessing the role that glaciers and seasonal snow play in the freshwater resources of Central and South Asia. The study area encompasses roughly 3 million square kilometers of the Himalaya, Karakoram, Hindu Kush, Pamir and Tien Shan mountain ranges that drain to five major rivers: the Ganges, Brahmaputra, Indus, Amu Darya and Syr Darya. We estimate daily snow and glacier ice contributions to the water balance. Our automated partitioning method generates daily maps of 1) snow over ice (SOI), 2) exposed glacier ice (EGI), 3) debris covered glacier ice (DGI) and 4) snow over land (SOL) using fractional snow cover, snow grain size, and annual minimum ice and snow from the 500 m MODIS-derived MODSCAG and MODICE products. Maps of snow and ice cover are validated using high-resolution (30 m) maps of snow, ice, and debris cover from Landsat. The probability of detection is 0.91 and precision is 0.85 for MODICE. We examine trends in annual and monthly snow and ice maps and use daily maps as inputs to a calibrated temperature-index model and an uncalibrated energy balance model, ParBal. Melt model results and measurements of isotopes and specific ions used as an independent validation of melt modeling indicate a sharp geographic contrast in the role of snow and ice melt to downstream water supplies between the arid Tien Shan and Pamir ranges of Central Asia, where melt water dominates dry season flows, and the monsoon influenced central and eastern Himalaya where rain controls runoff. We also compare melt onset and duration from the melt models to the Calibrated, Enhanced Resolution Passive Microwave Brightness Temperature Earth Science Data Record. Trend analysis of annual and monthly area of permanent snow and ice (the union of SOI and EGI) for 2000 to 2016 shows statistically significant negative trends in the Ganges and Brahmaputra basins. There are no statistically significant trends in permanent snow and ice in the other basins and no statistically significant trends in SOL, the renewable and seasonal component of snow and ice cover, in any of the five basins. This work gives a better understanding of the current hydrologic regime to guide realistic estimates of the future availability and vulnerability of water resources in these regions.

Glacial history and runoff components of the Tlikakila River Basin, Lake Clark National Park and Preserve, Alaska

USGS Publications Warehouse

Brabets, Timothy P.; March, Rod S.; Trabant, Dennis C.

2004-01-01

The Tlikakila River is located in Lake Clark National Park and Preserve and drains an area of 1,610 square kilometers (622 square miles). Runoff from the Tlikakila River Basin accounts for about one half of the total inflow to Lake Clark. Glaciers occupy about one third of the basin and affect the runoff characteristics of the Tlikakila River. As part of a cooperative study with the National Park Service, glacier changes and runoff characteristics in the Tlikakila River Basin were studied in water years 2001 and 2002. Based on analyses of remote sensing data and on airborne laser profiling, most glaciers in the Tlikakila River Basin have retreated and thinned from 1957 to the present. Volume loss from 1957-2001 from the Tanaina Glacier, the largest glacier in the Tlikakila River Basin, was estimated to be 6.1 x 109 cubic meters or 1.4 x 108 cubic meters per year. For the 2001 water year, mass balance measurements made on the three largest glaciers in the Tlikakila River BasinTanaina, Glacier Fork, and North Forkall indicate a negative mass balance. Runoff measured near the mouth of the Tlikakila River for water year 2001 was 1.70 meters. Of this total, 0.18 meters (11 percent) was from glacier ice melt, 1.27 meters (75 percent) was from snowmelt, 0.24 meters (14 percent) was from rainfall runoff, and 0.01 meters (1 percent) was from ground water. Although ground water is a small component of runoff, it provides a critical source of warm water for fish survival in the lower reaches of the Tlikakila River.

Prediction of River Flooding using Geospatial and Statistical Analysis in New York, USA and Kent, UK

NASA Astrophysics Data System (ADS)

Marsellos, A.; Tsakiri, K.; Smith, M.

2014-12-01

Flooding in the rivers normally occurs during periods of excessive precipitation (i.e. New York, USA; Kent, UK) or ice jams during the winter period (New York, USA). For the prediction and mapping of the river flooding, it is necessary to evaluate the spatial distribution of the water (volume) in the river as well as study the interaction between the climatic and hydrological variables. Two study areas have been analyzed; one in Mohawk River, New York and one in Kent, United Kingdom (UK). A high resolution Digital Elevation Model (DEM) of the Mohawk River, New York has been used for a GIS flooding simulation to determine the maximum elevation value of the water that cannot continue to be restricted in the trunk stream and as a result flooding in the river may be triggered. The Flooding Trigger Level (FTL) is determined by incremental volumetric and surface calculations from Triangulated Irregular Network (TIN) with the use of GIS software and LiDAR data. The prediction of flooding in the river can also be improved by the statistical analysis of the hydrological and climatic variables in Mohawk River and Kent, UK. A methodology of time series analysis has been applied for the decomposition of the hydrological (water flow and ground water data) and climatic data in both locations. The KZ (Kolmogorov-Zurbenko) filter is used for the decomposition of the time series into the long, seasonal, and short term components. The explanation of the long term component of the water flow using the climatic variables has been improved up to 90% for both locations. Similar analysis has been performed for the prediction of the seasonal and short term component. This methodology can be applied for flooding of the rivers in multiple sites.

Coastal conduit in southwestern Hudson Bay (Canada) in summer: Rapid transit of freshwater and significant loss of colored dissolved organic matter

NASA Astrophysics Data System (ADS)

Granskog, Mats A.; MacDonald, Robie W.; Kuzyk, Zou Zou A.; Senneville, Simon; Mundy, Christopher-John; Barber, David G.; Stern, Gary A.; Saucier, Francois

2009-08-01

Distributions of freshwater (sea-ice melt and runoff) were investigated along inshore-offshore sections in southwestern Hudson Bay for fall conditions. Conductivity-temperature-density profiles and bottle samples collected for salinity, oxygen isotope (δ18O), and colored dissolved organic matter (CDOM) analyses were used to discriminate between contributions of river water (RW) and sea-ice melt (SIM). Stations had a fresh summer surface mixed layer 5-25 m thick overlying a cold subsurface layer indicative of the previous winter's polar mixed layer (PML). The fraction of RW decreased strongly with distance from shore, while the opposite was true for SIM. The majority of RW was constrained in a coastal domain within 100-150 km from shore, which, because of high alongshore velocities, accounts for the majority of freshwater and volume transports. On the basis of freshwater inventories and composition, brine and RW accumulate in the PML over winter because of ice formation and downward mixing. The summer surface circulation results in an annual net export of SIM from the region. Residence times for freshwater components in the southwestern sector of the bay, based on currents derived from a 3-D ocean model for Hudson Bay, are about 1-10 months, implying rapid transit of freshwater. Despite the short residence time for RW (1-3 months), CDOM is significantly photobleached and provides an unreliable tracer for RW. Photobleaching represents an important sink for dissolved organic carbon entering from rivers and could, in part, explain why Hudson Bay is only a minor sink for atmospheric CO2 in the open water season.

Water survey of Canada: Application for use of ERTS-A for retransmission of water resources data

NASA Technical Reports Server (NTRS)

Halliday, R. A. (Principal Investigator); Reid, I. A.

1974-01-01

The author has identified the following significant results. Water resources data were retransmitted from nine data collection platforms (DCP) located in remote regions of Canada. The DCPs located in the Arctic operated in temperatures lower than -40 C and the DCP antennas have survived wind speeds of greater than 80 kph and snow loads of a depth of one metre. Ice-out indicators were installed at a few DCP sites. The purpose of these indicators was to enable the detection of the movement of ice out of river channel during spring break-up. The suitability of satellite retransmission as a means of obtaining data from remote areas of Canada continues to be demonstrated. A modest expansion of the DCP network is planned.

Radar with Color-wrapped Height Fringes, Syracuse and vicinity, New York State

NASA Technical Reports Server (NTRS)

2000-01-01

This image shows the northern part of central New York State, a landscape sculpted by the ice sheets of the last ice age. Lake Ontario runs across the top of the image. The city of Syracuse is the radar-bright area next to the dark Onandaga Lake, below and to the right of the image center. The larger dark area on the right side is Oneida Lake. Several of the Finger Lakes are visible as long narrow dark patches on the left side of the image: Cayuga (north end only), Owasco, Skaneateles, and Otisco (left to right). The city of Auburn is at the north (top) end of Owasco Lake. Between 25,000 and 18,000 years ago, central New York was covered by a vast ice sheet 1,000-1,300 meters (3,300-4,300 feet) thick, similar to the one now covering Greenland. The land shows many marks left by the glaciers. Numerous small, elongated hills rise out of the plains south of Lake Ontario at the top and center of the image. These are drumlins, molded out of sand and clay at the bottom of the ice sheet. The shape of the drumlins indicates the direction that the ice sheet was moving and varies across the image, providing clues for scientists who study past climatic changes. The hills at the lower left of the image have been carved by the glaciers into 'U'-shaped valleys with steep sides and flat bottoms. In several places 'dry' valleys cross ridges without a modern river. These were probably carved at a time when the last stages of the glacier blocked rivers from flowing down the big valleys and forced the rivers to cut across the ridges. The wispy features along the shore of Lake Ontario are ice that was floating on the lake when SRTM acquired this image in February.

This image combines two types of data from the Shuttle Radar Topography Mission. The image brightness corresponds to the strength of the radar signal reflected from the ground, while colors show the elevation as measured by SRTM. Each cycle of colors (from red through green back to red) represents an equal amount of elevation difference similar to contour lines on a standard topographic map. Each color contour represents 100 meters of elevation change.

This image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

Size: 80 by 110 kilometers (50 by 70 miles) Location: 43.0 deg. North lat., 76.3 deg. West lon. Orientation: North toward the upper right Date Acquired: February 13, 2000

"Enemies Like a Road Covered with Ice": The Utah Navajos' Experience during the Long Walk Period, 1858-1868

ERIC Educational Resources Information Center

Hornsby, Sarah; McPherson, Robert S.

2009-01-01

Much has been written of the Navajo Long Walk period when the Navajo people, following what appears to be a fairly short resistance, surrendered in droves to the US military, collected at Fort Defiance and other designated sites, then moved in a series of "long walks" to Fort Sumner (Hweeldi) on the Pecos River in eastern New Mexico.…

Spaceborne Microwave Imagers

NASA Technical Reports Server (NTRS)

Stacey, J. M.

1991-01-01

Monograph presents comprehensive overview of science and technology of spaceborne microwave-imaging systems. Microwave images used as versatile orbiting, remote-sensing systems to investigate atmospheres and surfaces of planets. Detect surface objects through canopies of clouds, measure distributions of raindrops in clouds that their views penetrate, find meandering rivers in rain forests and underground water in arid regions, and provide information on ocean currents, wakes, ice/water boundaries, aircraft, ships, buoys, and bridges.

ROSS: The Remotely-Operated Surface Sampler - A MediumEndurance, Precision-Navigated Platform Optimized for Uncontaminated Measurement of Upper-Ocean Velocity, Density and Turbulence

DTIC Science & Technology

2015-09-30

ocean  surface.   It  is ideal for studying fronts, river plumes, near-­‐surface  phenomena like ice-­‐ melt  or rain   puddles,  air...regions  too  dangerous  for manned craft (like near glacier faces),  and for interpreting  the  undersea structure  of satellite

Ice dynamics of Himalayan glaciers (Himachal Pradesh, India) using TerraSAR-X/TanDEM-X data.

NASA Astrophysics Data System (ADS)

Vijay, Saurabh; Braun, Matthias

2015-04-01

Mountain glaciers are the natural indicators of climate change. Himalaya is a part of widely spread mountain range consisting of second largest ice mass after polar region. The glaciers in Himalaya are located in Himachal Pradesh and other territories of India. The precipitation in the region is influenced by both Indian summer monsoon and mid-latitude winter westerlies. The glacier discharge influences the river basins and provides fresh water for various infrastructural necessities of urbanization in the state. The study aims to estimate the ice thickness and volume change during the decade (2011-2000) and annually during 2011-2014. For this, TanDEM-X DEMs are subtracted from the SRTM C/X band DEM of 2000. In addition, ice flow dynamics are quantified by the constellation of TerraSAR-X/TanDEM-X data using SAR offset tracking method. The primary investigations reveal that the terminus velocity of Bada Shigri (G077683E32169N), the biggest glacier of the state, Chhota Shigri( G077513E32227N), a bench-mark glacier, and other glacier (G077547E32162N) in 2011 found out to be < 2cm/day. The upper stream velocities of the glaciers are increased linearly and influenced by glacier tributaries.

Statewide Floods in Pennsylvania, January 1996

USGS Publications Warehouse

Thompson, R.E.

1996-01-01

Rivers and streams throughout Pennsylvania (fig. 1) experienced major flooding during January 1996. Flood stages (water-surface heights) and discharges (flows) in many of the Commonwealth's waterways were measured by the U.S. Geological Survey (USGS) and approached or exceeded record levels established during previous floods. Setting the stage for the flooding was an unusually cold beginning to the winter of 1995-96, which resulted in the early formation of ice in streams statewide. The anomaly of early ice was followed by a sequence of unusual meteorological events in January 1996, which, in many areas, resulted in the most widespread and severe flooding since that produced by tropical storm Agnes in June 1972. Locally, the flooding was the worst since August 1955 and, in some areas, since March 1936. In approximately 50 localities throughout Pennsylvania, flood effects were magnified when ice jams caused temporary damming of stream channels, resulting in the rapid rise of water levels and the subsequent overflow of water and ice onto flood plains. During the floods, the USGS collected stream-stage information on a near real- 42°-GffEAWa/CESJ DRWNAG. time basis at 189 streamflow-gaging stations across the Commonwealth. This information was used by various Federal, State, and local agencies to prepare flood forecasts and develop plans for emergency response.

Marine Arctic Ecosystem Study (MARES) - An Integrated Approach to the Dynamics of the Beaufort Sea

NASA Astrophysics Data System (ADS)

Wiese, F. K.; Gryba, R.; Kelly, B. P.

2016-02-01

MARES is an integrated ecosystem research initiative coordinated and planned by the Bureau of Ocean Energy Management, the Office of Naval Research, the National Aeronautics and Space Administration, the U.S. Coast Guard, and Shell through the National Oceanographic Partnership Program. The overarching goal is to advance our knowledge of the structure and function of the Beaufort Sea marine ecosystem so as to link atmospheric and oceanic drivers to sea ice patterns and marine mammal distribution and availability to local subsistence communities. The study, funded in 2014, focuses on the marine ecosystem along the Beaufort Sea shelf from Barrow, Alaska to the Mackenzie River delta in Canada and is scheduled to include bio-physical moorings along the US-Canadian border, glider deployments packed with bio-physical sensors, tagging of whales and ice-associated seals with satellite CTD-Fluorometer tags, biophysical and chemical cruises including the measurement and characterization of hydrography, ice, nutrients, primary and secondary production, carbon budgets, benthic fauna, fish, as well as analysis of freshwater input and chemical loadings, and ecosystem modeling. This presentation will focus on preliminary results from the ice seal tagging that started in the summer of 2015 and describe some of the planning and possibilities for partnerships for the more comprehensive 2016 field season and beyond.

Imprint of Late Quaternary Climate Change on the Mid-Atlantic Landscape

NASA Astrophysics Data System (ADS)

Pavich, M.; Markewich, H.; Newell, W. L.; Litwin, R.; Smoot, J.; Brook, G.

2009-12-01

Recent geomorphic, lithostratigraphic, palynologic and chronostratigraphic investigations of the mid-Atlantic region show that much of the modern landscape flanking the Chesapeake Bay and the Potomac River is developed on late Quaternary sediments. These deposits, dated by OSL and 14C, include transgressive marine and estuarine sediments deposited between 120ka and 32ka, and parabolic dunes formed between 32ka and 15ka. The stacked estuarine units were deposited in a subsiding basin as eustatic sea level fell from +7m to -60m. The estuarine units contain pollen that provides evidence for millennial scale climate fluctuations. The dunes formed during the period of rapid expansion of the Laurentide Ice Sheet as sea level fell to -120m. Permafrost features such as frost wedges and periglacial “pots” formed during cold intervals associated with marine oxygen isotope stages 4 and 2. This periglacial climate, along with glacioisostatic adjustments to growth and decay of the Laurentide Ice Sheet, affected landscape processes at least as far south as the Potomac River valley. While many of these features were recognized in earlier mapping and stratigraphic investigations, OSL dating has greatly extended the range of available dates and significantly improved our understanding of the impacts of highly variable periglacial climate on this region.

Fishing effort and catch composition of urban market and rural villages in Brazilian Amazon.

PubMed

Hallwass, Gustavo; Lopes, Priscila Fabiana; Juras, Anastacio Afonso; Silvano, Renato Azevedo Matias

2011-02-01

The management of small-scale freshwater fisheries in Amazon has been based usually on surveys of urban markets, while fisheries of rural villages have gone unnoticed. We compared the fishing characteristics (catch, effort and selectivity) between an urban market and five small villages in the Lower Tocantins River (Brazilian Amazon), downstream from a large reservoir. We recorded 86 and 601 fish landings in the urban market and villages, respectively, using the same methodology. The urban fishers showed higher catch per unit of effort, higher amount of ice (related to a higher fishing effort, as ice is used to store fish catches) and larger crew size per fishing trip, but village fishers had a higher estimated annual fish production. Conversely, urban and village fishers used similar fishing gear (gillnets) and the main fish species caught were the same. However, village fishers showed more diverse strategies regarding gear, habitats and fish caught. Therefore, although it underestimated the total amount of fish caught in the Lower Tocantins River region, the data from the urban market could be a reliable indicator of main fish species exploited and fishing gear used by village fishers. Monitoring and management should consider the differences and similarities between urban and rural fisheries, in Amazon and in other tropical regions.

Assessment of snow-glacier melt and rainfall contribution to stream runoff in Baspa Basin, Indian Himalaya.

PubMed

Gaddam, Vinay Kumar; Kulkarni, Anil V; Gupta, Anil Kumar

2018-02-20

Hydrological regimes of most of the Himalayan river catchments are poorly studied due to sparse hydro-meteorological data. Hence, stream runoff assessment becomes difficult for various socio-industrial activities in the Himalaya. Therefore, an attempt is made in this study to assess the stream runoff of Baspa River in Himachal Pradesh, India, by evaluating the contribution from snow-ice melt and rainfall runoff. The total volume of flow was computed for a period of 15 years, from 2000 to 2014, and validated with the long-term field discharge measurements, obtained from Jaipee Hydropower station (31° 32' 35.53″ N, 78° 00' 54.80″ E), at Kuppa barrage in the basin. The observations suggest (1) a good correlation (r 2  > 0.80) between the modeled runoff and field discharge measurements, and (2) out of the total runoff, 81.2% are produced by snowmelt, 11.4% by rainfall, and 7.4% from ice melt. The catchment receives ~75% of its total runoff in the ablation period (i.e., from May to September). In addition, an early snowmelt is observed in accumulation season during study period, indicating the significant influence of natural and anthropogenic factors on high-altitude areas.

Fishing Effort and Catch Composition of Urban Market and Rural Villages in Brazilian Amazon

NASA Astrophysics Data System (ADS)

Hallwass, Gustavo; Lopes, Priscila Fabiana; Juras, Anastacio Afonso; Silvano, Renato Azevedo Matias

2011-02-01

The management of small-scale freshwater fisheries in Amazon has been based usually on surveys of urban markets, while fisheries of rural villages have gone unnoticed. We compared the fishing characteristics (catch, effort and selectivity) between an urban market and five small villages in the Lower Tocantins River (Brazilian Amazon), downstream from a large reservoir. We recorded 86 and 601 fish landings in the urban market and villages, respectively, using the same methodology. The urban fishers showed higher catch per unit of effort, higher amount of ice (related to a higher fishing effort, as ice is used to store fish catches) and larger crew size per fishing trip, but village fishers had a higher estimated annual fish production. Conversely, urban and village fishers used similar fishing gear (gillnets) and the main fish species caught were the same. However, village fishers showed more diverse strategies regarding gear, habitats and fish caught. Therefore, although it underestimated the total amount of fish caught in the Lower Tocantins River region, the data from the urban market could be a reliable indicator of main fish species exploited and fishing gear used by village fishers. Monitoring and management should consider the differences and similarities between urban and rural fisheries, in Amazon and in other tropical regions.

Organic carbon export from the Greenland Ice Sheet: sources, sinks and downstream fluxes

NASA Astrophysics Data System (ADS)

Wadham, J. L.; Lawson, E.; Tranter, M.; Stibal, M.; Telling, J.; Lis, G. P.; Nienow, P. W.; Anesio, A. M.; Butler, C. E.

2012-12-01

Runoff from small glacier systems has been shown to contain dissolved organic carbon (DOC) rich in low molecular weight (LMW), and hence more labile forms, designating glaciers as an important source of carbon for downstream heterotrophic activity. Here we assess glacier surfaces as potential sources of labile DOC to downstream ecosystems, presenting data from a wide range of glacier systems to determine sources and sinks of DOC in glacial and proglacial systems. We subsequently focus upon the Greenland Ice Sheet (GrIS) which is the largest source of glacial runoff at present (400 km3 yr-1), with predicted increases in future decades. We report high fluxes of particulate organic carbon (POC), DOC and LMW labile fractions from a large GrIS catchment during two contrasting melt seasons. POC dominates OC export, is sourced from the ice sheet bed and contains a significant bioreactive component (~10% carbohydrates). The LMW-DOC "labile" fraction derives almost entirely from microbial activity on the ice sheet surface, which is supported by data from glacier systems also presented here. Annual fluxes of DOC, POC and labile components were lower in 2010 than 2009, despite a ~2 fold increase in runoff fluxes in 2010, suggesting production-limited DOC/POC sources. Scaled to the entire ice sheet, combined DOC and POC fluxes are of a similar order of magnitude to other large Arctic river systems and may represent an important source of organic carbon to the North Atlantic, Greenland and Labrador Seas.

Storage and release of organic carbon from glaciers and ice sheets

NASA Astrophysics Data System (ADS)

Hood, Eran; Battin, Tom J.; Fellman, Jason; O'Neel, Shad; Spencer, Robert G. M.

2015-02-01

Polar ice sheets and mountain glaciers, which cover roughly 11% of the Earth's land surface, store organic carbon from local and distant sources and then release it to downstream environments. Climate-driven changes to glacier runoff are expected to be larger than climate impacts on other components of the hydrological cycle, and may represent an important flux of organic carbon. A compilation of published data on dissolved organic carbon from glaciers across five continents reveals that mountain and polar glaciers represent a quantitatively important store of organic carbon. The Antarctic Ice Sheet is the repository of most of the roughly 6 petagrams (Pg) of organic carbon stored in glacier ice, but the annual release of glacier organic carbon is dominated by mountain glaciers in the case of dissolved organic carbon and the Greenland Ice Sheet in the case of particulate organic carbon. Climate change contributes to these fluxes: approximately 13% of the annual flux of glacier dissolved organic carbon is a result of glacier mass loss. These losses are expected to accelerate, leading to a cumulative loss of roughly 15 teragrams (Tg) of glacial dissolved organic carbon by 2050 due to climate change -- equivalent to about half of the annual flux of dissolved organic carbon from the Amazon River. Thus, glaciers constitute a key link between terrestrial and aquatic carbon fluxes, and will be of increasing importance in land-to-ocean fluxes of organic carbon in glacierized regions.

Storage and release of organic carbon from glaciers and ice sheets

USGS Publications Warehouse

Hood, Eran; Battin, Tom J.; Fellman, Jason; O'Neel, Shad; Spencer, Robert G. M.

2015-01-01

Polar ice sheets and mountain glaciers, which cover roughly 11% of the Earth's land surface, store organic carbon from local and distant sources and then release it to downstream environments. Climate-driven changes to glacier runoff are expected to be larger than climate impacts on other components of the hydrological cycle, and may represent an important flux of organic carbon. A compilation of published data on dissolved organic carbon from glaciers across five continents reveals that mountain and polar glaciers represent a quantitatively important store of organic carbon. The Antarctic Ice Sheet is the repository of most of the roughly 6 petagrams (Pg) of organic carbon stored in glacier ice, but the annual release of glacier organic carbon is dominated by mountain glaciers in the case of dissolved organic carbon and the Greenland Ice Sheet in the case of particulate organic carbon. Climate change contributes to these fluxes: approximately 13% of the annual flux of glacier dissolved organic carbon is a result of glacier mass loss. These losses are expected to accelerate, leading to a cumulative loss of roughly 15 teragrams (Tg) of glacial dissolved organic carbon by 2050 due to climate change — equivalent to about half of the annual flux of dissolved organic carbon from the Amazon River. Thus, glaciers constitute a key link between terrestrial and aquatic carbon fluxes, and will be of increasing importance in land-to-ocean fluxes of organic carbon in glacierized regions.

Himalayas as seen from STS-66 shuttle Atlantis

NASA Image and Video Library

1994-11-14

View is southeastward across China (Tibet), half of Nepal and India. The partly frozen lake near the center of the frame is Pei-Ku T'so ("Bos-tie Lake"). The central Himalaya stretches from Mount Everest on the left past Annapurna on the right. Large tributaries converge to form the Ganges River, flowing through the lowland basin south of the Himalaya. This photograph illustrates the rain shadow effect of the Himalaya Chain; wet, warm air from the Indian Ocean is driven against the mountains, lifted, and drained of water that forms ice caps, the abundant rivers, and forests of the foothills. In contrast the high plateau of Tibet is arid, composed largely of topographically-closed basins because stream flow is inadequate to form integrated drainage networks.

Climate Changes Documented in Ice Core Records from Third Pole Glaciers, with Emphasis on the Guliya Ice Cap in the Western Kunlun Mountains over the Last 100 Years

NASA Astrophysics Data System (ADS)

Thompson, L. G.; Yao, T.; Beaudon, E.; Mosley-Thompson, E.; Davis, M. E.; Kenny, D. V.; Lin, P. N.

2016-12-01

The Third Pole (TP) is a rapidly warming region containing 100,000 km2 of ice cover that collectively holds one of Earth's largest stores of freshwater that feeds Asia's largest rivers and helps sustain 1.5 billion people. Information on the accelerating warming in the region, its impact on the glaciers and subsequently on future water resources is urgently needed to guide mitigation and adaptation policies. Ice core histories collected over the last three decades across the TP demonstrate its climatic complexity and diversity. Here we present preliminary results from the flagship project of the Third Pole Environment Program, the 2015 Sino-American cooperative ice core drilling of the Guliya ice cap in the Kunlun Mountains in the western TP near the northern limit of the region influenced by the southwest monsoon. Three ice cores, each 51 meters in length, were recovered from the summit ( 6700 masl) while two deeper cores, one to bedrock ( 310 meters), were recovered from the plateau ( 6200 masl). Across the ice cap the net balance (accumulation) has increased annually by 2.3 cm of water equivalent from 1963-1992 to 1992-2015, and average oxygen isotopic ratios (δ18O) have enriched by 2‰. This contrasts with the recent ablation on the Naimona'nyi glacier located 540 km south of Guliya in the western Himalaya. Borehole temperatures in 2015 on the Guliya plateau have warmed substantially in the upper 30 meters of the ice compared to temperatures in 1992, when the first deep-drilling of the Guliya plateau was conducted. Compared with glaciers in the northern and western TP, the Himalayan ice fields are more sensitive to both fluctuations in the South Asian Monsoon and rising temperatures in the region. We examine the climatic changes of the last century preserved in ice core records from sites throughout the TP and compare them with those reconstructed for earlier warm epochs, such as the Medieval Climate Anomaly ( 950-1250 AD), the early Holocene "Hypsithermal" ( 5 to 9 kyr BP) and the Eemian (present only in Guliya). The latter epoch is the latest period when Earth may have been as warm as today and thus serves as an analog for the developing greenhouse world.

Matusevich Glacier

NASA Image and Video Library

2017-12-08

NASA image acquired September 6, 2010 The Matusevich Glacier flows toward the coast of East Antarctica, pushing through a channel between the Lazarev Mountains and the northwestern tip of the Wilson Hills. Constrained by surrounding rocks, the river of ice holds together. But stresses resulting from the glacier’s movement make deep crevasses, or cracks, in the ice. After passing through the channel, the glacier has room to spread out as it floats on the ocean. The expanded area and the jostling of ocean waves prompts the ice to break apart, which it often does along existing crevasses. On September 6, 2010, the Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite captured this natural-color image of the margin of Matusevich Glacier. Shown here just past the rock-lined channel, the glacier is calving large icebergs. Low-angled sunlight illuminates north-facing surfaces and casts long shadows to the south. Fast ice anchored to the shore surrounds both the glacier tongue and the icebergs it has calved. Compared to the glacier and icebergs, the fast ice is thinner with a smoother surface. Out to sea (image left), the sea ice is even thinner and moves with winds and currents. Matusevich Glacier does not drain a significant amount of ice off of the Antarctic continent, so the glacier’s advances and retreats lack global significance. Like other Antarctic glaciers, however, Matusevich helps glaciologists form a larger picture of Antarctica’s glacial health and ice sheet volume. NASA Earth Observatory image created by Jesse Allen and Robert Simmon, using EO-1 ALI data provided courtesy of the NASA EO-1 team. Caption by Michon Scott based on image interpretation by Robert Bindschadler, NASA Goddard Space Flight Center, and Walt Meier, National Snow and Ice Data Center. Instrument: EO-1 - ALI Credit: NASA Earth Observatory NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook To download the full resolution image go to: earthobservatory.nasa.gov/IOTD/view.php?id=46840

Tibetan Glaciers as Integrators and Sentinels of Climate Change

NASA Astrophysics Data System (ADS)

Thompson, L. G.; Tandong, Y.; Davis, M. E.; Kehrwald, N. M.; Mosley-Thompson, E. S.

2008-12-01

Information from ice cores collected over the last two decades across the Tibetan Plateau demonstrates that this is a climatically diverse and complex region. Records spanning more than 500,000 years have been recovered from the Guliya ice cap in the far northwestern Kunlun Mountains, where the climate is dominated by the westerly flow over the Eurasian land mass. Shorter records (less than 10,000 years) have been recovered from ice fields in the central Himalaya to the south, where a monsoonal climate regime dominates and the annual accumulation is high. On decadal and longer timescales IPCC climate models predict that continued anthropogenic greenhouse gas emissions will force air temperature to increase faster at higher elevations. This vertical amplification will be greatest in low latitudes due to upper tropospheric humidity and water vapor feedback. Meteorological records across the Tibetan Plateau indicate that temperatures have risen since the mid-1950s and the rate of warming is greater (0.3°C per decade) at the higher elevation stations. Likewise, the stable isotopic compositions of ice cores across the Plateau show an overall the 20th Century enrichment that is greatest at the highest elevation sites. Glaciers in the central Himalayas, including many around the Tibetan Plateau, are experiencing an accelerating rate of ice loss, due in part to current temperature trends and associated feedbacks. Ice loss in the central Himalayas is evident from ice cores recovered in 2006 from the Naimona'nyi ice field. Unlike previous cores from glaciers around the world, including those drilled across the Tibetan Plateau, the Naimona'nyi cores lack the elevated levels of beta radioactivity from the decay of 36Cl and 3H associated with atmospheric thermonuclear bomb testing in the 1950s and 1960s. This suggests that net mass (ice) loss has exceeded accumulation on this glacier since at least 1950. If the climate conditions that govern the mass balance on Naimona'nyi extend to other glaciers in the region, the implications for future water resources in South Asia could be dire as these glaciers feed the headwaters of the Indus, Ganges and Brahmaputra Rivers which sustain the world's most populous region.

Detection of dual effects of degradation of perennial snow and ice covers on the hydrologic regime of a Himalayan river basin by stream water availability modeling

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Biswajit

2012-01-01

SummaryIn river basins where melt water from snow and ice constitutes a dominant component of stream discharge during summer, degradation or reduction of perennial snow and ice covered areas ( SCA P) has a profound effect on stream water availability in those basins. Degradation of SCA P that includes glaciers is a globally widespread phenomenon observed in the recently past decades; its cause has been attributed to global warming and its consequence is expected to dramatically alter the flow regimes of the rivers draining the terrains. The predicted change in flow regime is an initial increase in summer flows in the early decades of 21st century followed by sharp decline of the same during the later parts of the century. Estimation of SCA P within the Upper Indus Basin (UIB), straddling the western ranges of the Greater Himalayas, Karakoram Mountains, and the eastern mountain ranges of the Hindu Kush, shows that from 1992 to 2010 there has been about 2.15% reduction in SCA P. A spatially distributed basin-scale stream water availability model is presented to calculate monthly river discharges at critical hydrologic junctions within UIB. Model calculations for the years 1992, 2000, and 2008, show that due to the degradation of the SCA P within the basin, there has been significant decrease in summer discharges at various hydrologic junctions. The percentage decline in flows varies from 10% to 22%, depending on the locations of the junctions within the basin. The space-dependence of these variations reflects differential degradation of SCA P in various parts of the basin. Furthermore, the time of peak discharge at all of the hydrological junctions has shifted from middle/late summer to late spring/early summer as another outcome of SCA P reduction. Such temporal shifting of nival regimes to early part of warmer season has also been predicted by global warming models. However, the case study presented here for a major Himalayan river basin demonstrates that such shifting of peak discharge in the time domain can also take place simply due to retreat of the equilibrium line. Thus, the effects of a warming climate have possibly been already set within UIB. Instead of experiencing an increased pulse of summer flows for the next few decades, summer flows within this basin are expected to decline. Changes in the timing of peak flows can have adverse effects on multipurpose water resources management without appropriate adaptation and mitigation measures. Monthly average stream flow data with 35 year period of record from a key gauging station support the findings of the model results. Similarly, digital maps of SCA P at different time periods within a key catchment of UIB, containing one of the major glaciers, show retreat of glacial lobes and significant decrease in total SCA P taking place during the past decades.

Earth Observations taken by the Expedition 39 Crew

NASA Image and Video Library

2014-04-22

ISS039E14821 (22 April 2014) --- In this late afternoon shot, one of the Expedition 39 crew members aboard the International Space Station looked back toward the setting sun and used a 145mm lens on an electronic still camera to capture the hook-shaped southern half of Lake Baikal in eastern Russia on April 22, 2014. Most of the lake is covered with dull gray ice. The brightest point in the center of the image is the reflection of the sun’s rays off a small zone of open water (center) where the ice has begun to melt. Broken ice masses appear adjacent to the sunglint point (center). The sun’s rays are also reflected off the water surface of the straight Angara River, the main outlet of the lake (top right). Lake Baikal is 636 kilometers long (395 miles). It is the deepest lake in the world and holds the largest amount of fresh water. Individual smoke plumes from factories arc away from the north shore (top left). Large smoke palls from wildfires appear in upper right.

Modelling river discharge and precipitation from estuarine salinity in the northern Chesapeake Bay: Application to Holocene palaeoclimate

USGS Publications Warehouse

Saenger, C.; Cronin, T.; Thunell, R.; Vann, C.

2006-01-01

Long-term chronologies of precipitation can provide a baseline against which twentieth-century trends in rainfall can be evaluated in terms of natural variability and anthropogenic influence. However, there are relatively few methods to quantitatively reconstruct palaeoprecipitation and river discharge compared with proxies of other climatic factors, such as temperature. We developed autoregressive and least squares statistical models relating Chesapeake Bay salinity to river discharge and regional precipitation records. Salinity in northern and central parts of the modern Chesapeake Bay is influenced largely by seasonal, interannual and decadal variations in Susquehanna River discharge, which in turn are controlled by regional precipitation patterns. A power regressive discharge model and linear precipitation model exhibit well-defined decadal variations in peak discharge and precipitation. The utility of the models was tested by estimating Holocene palaeoprecipitation and Susquehanna River palaeodischarge, as indicated by isotopically derived palaeosalinity reconstructions from Chesapeake Bay sediment cores. Model results indicate that the early-mid Holocene (7055-5900 yr BP) was drier than the late Holocene (1500 yr BP - present), the 'Mediaeval Warm Period' (MWP) (1200-600 yr BP) was drier than the 'Little Ice Age' (LIA) (500-100 yr BP), and the twentieth century experienced extremes in precipitation possibly associated with changes in ocean-atmosphere teleconnections. ?? 2006 Edward Arnold (Publishers) Ltd.

Earth Observations taken by Expedition 38 crewmember

NASA Image and Video Library

2014-02-22

ISS038-E-057979 (22 Feb. 2014) --- This image, photographed by one of the Expedition 38 crew members aboard the International Space Station, shows the city of Green Bay, Wisconsin at the southern end of icebound Green Bay. This arm of Lake Michigan is six miles wide as seen in this view. The heavy snowfalls of the winter of 2014 cover the landscape. Combined with low sun illumination of a winter day, all surfaces appear as shades of gray. Fields appear brighter (top right, lower right), the cityscape (lower half of the image) appears as a checkerboard of grays, and forests (top left) appear dark. The center of the city lies on the Fox River, one of the few larger rivers in the United States that flow north. Open water appears as dark patches at the mouth of the river where a power station emits warm water. Thinner (grayer) ice can be detected where slightly warmer water extends from the river mouth towards Long Tail Point, an ancient shoreline of the bay. Crews aboard the space station do not usually take such detailed photographs because of the difficulty of getting sharp images with long lenses (in this case a 1000mm lens). Streets and bridges crossing the Fox River appear quite clearly.

Is proglacial field an important contributor to runoff in glacierized watershed? Lesson learned from a case study in Duke River watershed, Yukon, Canada.

NASA Astrophysics Data System (ADS)

Chesnokova, A.; Baraer, M.

2017-12-01

Sub-Arctic glacierized catchments are complex hydrological systems of paramount importance not only for water resources management but also for various ecosystem services. Those areas are environmentally fragile and host many climate-sensitive components of hydrological cycle. In a context of shifting from glacial to non-glacial regimes in Sub-Arctic, this study focuses on understanding hydrological role of proglacial field in runoff generation in headwaters of Duke River watershed, Canada, by comparing to that of alpine meadow (area that is not recently reworked by glacier). Duke Glacier, as many glaciers in St. Elias Mountains, is a surging glacier, and produced debris-charged dead-ice masses once the last surge has seized. In addition, such features as ice-cored moraines and taluses are found in proglacial field. Those features are hypothesised to cause high storage capacity and complex groundwater distribution systems which might affect significantly watershed hydrology. In order to estimate the contribution of different components of the alpine meadow and the proglacial field to runoff, HBCM, a multi-component distributed hydrochemical mixing model (Baraer et al., 2015) was applied. During field campaign in June 2016, 157 samples were taken from possible hydrological sources (end-members) and from main stream, and analysed for major ions, dissolved organic compounds and heavy stable water isotopes. End-members contribution was quantified based on tracer concentration at mixing points. Discharge was measured 6 km downstream from the glacier snout so that both proglacial field and alpine meadow occupy comparable areas of the catchment. Results show the difference between main water sources for the two hydrological systems: buried ice, ice-cored moraines and groundwater sources within proglacial field, and groundwater and supra-permafrost water within alpine meadow. Overall contribution of glaciers during June 2016 exceeded the contribution of the rest of the components of hydrological system. However, water production from both proglacial field and alpine meadow was significant, with proglacial field yielding more water than alpine meadow. Since the Duke Glacier keeps retreating, the area of proglacial field is increasing as well as it role in runoff generation in the area.

River conferences under temperate valley glaciers

NASA Astrophysics Data System (ADS)

Lane, Stuart; Egli, Pascal; Irving, James

2017-04-01

Both geophysical measurements (ground penetrating radar) and hydrological inference has shown that subglacial drainage networks are dendritic and that means that they must have confluences. In general, there are very few studies of rivers under glaciers and almost no consideration at all of confluences, despite the fact that they could be a critical parameter in understanding coupling at the ice-sediment bed interface. Subglacial channels, normally known as conduits, are typically associated with the combined effect of hydraulic pressure driven ice melt (which opens them) and ice overburden pressure (which closes them). Inferences from dye break out curves shows that has the efficiency of ice melt increases progressively during the summer ablation season, melt rates closure rates and a channelized system becomes progressively more effective. Most recently, measurements at the Upper Arolla Glacier show that the effects of this growing efficiency is an evolution in the subglacial hydrological system towards higher peak flows and lower base flows later in the melt season. This increases the probability that late in the melt season, sediment transport becomes discontinuous, with overnight deposition and daytime erosion. This would in turn produce the rapid reductions in sediment transport capacity overnight needed to deposit sediment and to block conduits, increase basal water pressure and explain the hydraulic jacking observed in snout marginal zones at a time when it should not be expected. The question that follows is what effects do confluences have on this process? The geometry of subglacial channels is such that when they join they lead to rapid changes in hydraulic geometry. Crucially, these are likely to have a non-linear impact upon sediment transport capacity, which should reduce disproportionally in the conduits downstream of the junction. Thus, it is possible that confluence zones under glaciers become sites of very rapid sediment accumulation and blockage overnight. In this paper, we present some one-dimensional coupled hydraulic sediment transport modelling to show this process. It suggests that the dendritic form of the subglacial drainage network is the primary reason why sediment blockage occurs and suggests the need for a more in-depth assessment of how sediment moves through confluences under glaciers.

Dissolved methane in the Beaufort Sea and the Arctic Ocean, 1992-2009; sources and atmospheric flux

USGS Publications Warehouse

Lorenson, Thomas D.; Greinert, Jens; Coffin, Richard B.

2016-01-01

Methane concentration and isotopic composition was measured in ice-covered and ice-free waters of the Arctic Ocean during eleven surveys spanning the years of 1992-1995 and 2009. During ice-free periods, methane flux from the Beaufort shelf varies from 0.14 to 0.43 mg CH4 m-2 day-1. Maximum fluxes from localized areas of high methane concentration are up to 1.52 mg CH4 m-2 day-1. Seasonal buildup of methane under ice can produce short-term fluxes of methane from the Beaufort shelf that varies from 0.28 to 1.01 to mg CH4 m-2 day-1. Scaled-up estimates of minimum methane flux from the Beaufort Sea and pan-Arctic shelf for both ice-free and ice-covered periods range from 0.02 Tg CH4 yr-1 and 0.30 Tg CH4 yr-1 respectively to maximum fluxes of 0.18 Tg CH4 yr-1 and 2.2 Tg CH4 yr-1 respectively. A methane flux of 0.36 Tg CH4 yr-1from the deep Arctic Ocean was estimated using data from 1993-94. The flux can be as much as 2.35 Tg CH4 yr-1 estimated from maximum methane concentrations and wind speeds of 12 m/s, representing only 0.42% of the annual atmospheric methane budget of ~560 Tg CH4 yr-1. There were no significant changes in methane fluxes during the time period of this study. Microbial methane sources predominate with minor influxes from thermogenic methane offshore Prudhoe Bay and the Mackenzie River delta and may include methane from gas hydrate. Methane oxidation is locally important on the shelf and is a methane sink in the deep Arctic Ocean.

Arctic sea-ice variability and its implication to the path of pollutants under a changing climate

NASA Astrophysics Data System (ADS)

Castro-Morales, K.; Gerdes, R.; Riemann-Campe, K.; Köberle, C.; Losch, M.

2012-04-01

The increasing concentration of pollutants from anthropogenic origin in the Arctic atmosphere, water, sediments and biota has been evident during the last decade. The sea-ice is an important vehicle for pollutants in the Arctic Ocean. Pollutants are taken up by precipitation and dry atmospheric deposition over the snow and ice cover during winter and released to the ocean during melting. Recent changes in the sea-ice cover of the Arctic Ocean affect the fresh water balance and the oceanic circulation, and with it, the fate of pollutants in the system. The Arctic Ocean is characterized by complex dynamics and strong stratification. Thus, to evaluate the current and future changes in the Arctic circulation high-resolution models are needed. As part of the EU FP7 project ArcRisk (under the scope of the IPY), we use a high resolution regional sea-ice-ocean coupled model covering the Arctic Ocean and the subpolar North Atlantic based on the Massachusetts Institute of Technology - circulation model (MITgcm). Under realistic atmospheric forcing we obtain hindcast results of circulation patterns for the period 1990 - 2010 for validation of the model. We evaluate possible consequences on the pathways and transport of contaminants by downscaling future climate scenario runs available in the coupled model intercomparison project (CMIP3) for the following fifty years. Particular interest is set in the Barents Sea. In this shallow region strong river runoff, sea-ice delivered from the interior of the Arctic Ocean and warm waters from the North Atlantic current are main sources of contaminants. Under a changing climate, a higher input of contaminants delivered to surface waters is expected, remaining in the interior of the Arctic Ocean in a strongly stratified water column remaining.

Export of Nitrogen From the Yukon River Basin to the Bering Sea

NASA Astrophysics Data System (ADS)

Dornblaser, M. M.; Striegl, R. G.

2005-12-01

The US Geological Survey measured nitrogen export from the 831,400 km2 Yukon River basin during 2001-04 as part of a five year water quality study of the Yukon River and its major tributaries. Concentrations of NO2+NO3, NH4+DON, and particulate N were measured ~6 times annually during open water and once under ice cover at three locations on the Yukon River, and on the Porcupine and Tanana Rivers. Concentration and continuous flow data were used to generate daily and annual loads of N species. NH4 concentration was generally negligible when compared to DON concentration, allowing for comparison of the relative importance of DIN vs. DON export at various watershed scales. NO2 concentration was also small compared to NO3. At Pilot Station, the last site on the Yukon before it flows into the Yukon Delta and the Bering Sea, DIN, DON, and particulate N loads averaged 19.3 × 106 kg/yr, 52.6 × 106 kg/yr, and 39.1 × 106 kg/yr, respectively. Normalized for the watershed area at Pilot Station, corresponding N yields were 1.65, 4.52, and 3.35 mmol/m2/yr. DIN yield for the Yukon at Pilot Station is substantially less than the NO3 flux reported for tropical/temperate rivers such as the Amazon, the Yangtze, and the Mississippi. DIN yield in the upper Yukon River basin is similar to that of the Mackenzie and other arctic rivers, but increases substantially downstream. This is likely due to development around Fairbanks in the Tanana River basin. When compared to other headwater basins in the upper Yukon, the Tanana basin yields about four times more DIN and two times more particulate N, while DON yields are only slightly elevated.

Carbon dioxide and methane emissions from the Yukon River system

USGS Publications Warehouse

Striegl, Robert G.; Dornblaser, Mark M.; McDonald, Cory P.; Rover, Jennifer R.; Stets, Edward G.

2012-01-01

Carbon dioxide (CO2) and methane (CH4) emissions are important, but poorly quantified, components of riverine carbon (C) budgets. This is largely because the data needed for gas flux calculations are sparse and are spatially and temporally variable. Additionally, the importance of C gas emissions relative to lateral C exports is not well known because gaseous and aqueous fluxes are not commonly measured on the same rivers. We couple measurements of aqueous CO2 and CH4 partial pressures (pCO2, pCH4) and flux across the water-air interface with gas transfer models to calculate subbasin distributions of gas flux density. We then combine those flux densities with remote and direct observations of stream and river water surface area and ice duration, to calculate C gas emissions from flowing waters throughout the Yukon River basin. CO2emissions were 7.68 Tg C yr−1 (95% CI: 5.84 −10.46), averaging 750 g C m−2 yr−1 normalized to water surface area, and 9.0 g C m−2 yr−1 normalized to river basin area. River CH4 emissions totaled 55 Gg C yr−1 or 0.7% of the total mass of C emitted as CO2 plus CH4 and ∼6.4% of their combined radiative forcing. When combined with lateral inorganic plus organic C exports to below head of tide, C gas emissions comprised 50% of total C exported by the Yukon River and its tributaries. River CO2 and CH4 derive from multiple sources, including groundwater, surface water runoff, carbonate equilibrium reactions, and benthic and water column microbial processing of organic C. The exact role of each of these processes is not yet quantified in the overall river C budget.

Geothermal constraints on enrichment of boron and lithium in salt lakes: An example from a river-salt lake system on the northern slope of the eastern Kunlun Mountains, China

NASA Astrophysics Data System (ADS)

Tan, Hongbing; Chen, Jun; Rao, Wenbo; Zhang, Wenjie; Zhou, Huifang

2012-06-01

Some rivers on the northern slope of the eastern Kunlun Mountains in the Qaidam Basin, China, show very high concentrations of boron and lithium. Correspondingly, the salt lakes fed by these rivers show an unusual enrichment of boron and lithium, and become an important economic resource. The origin of boron and lithium has long been debated. The aim of this study is to analyze the water chemistry and hydrogen and oxygen isotopic composition of river water to understand the unusual enrichment of boron and lithium in the salt lakes of the Qaidam Basin. Oxygen and hydrogen isotope data show that the source of river water in the winter and summer originates from the Kunlun Mountain ice and snow melt water, respectively. The water chemistry shows that boron and lithium contents are high but little variable with seasons in the Nalenggele River and Wutumeiren River waters. By contrast, other rivers have much lower lithium and boron contents. Moreover, the contents of B3+ and Li+ in the river loads or bed sands show little difference amongst the rivers. This indicates that removal by adsorption or input by surface rock weathering is not the main controlling factor of the B3+ and Li+ variation in the rivers. Rivers with high B3+ and Li+ content are chemically similar to geothermal waters in the Tibetan Plateau. In addition, the source area of the Nalenggele River is located in a collision zone of the Kunlun Mountains and Altun Mountains. Large and deep faults can serve as conduits for geothermal fluids. Thus, deep geothermal waters in the source area can easily migrate to the surface and discharge as springs feeding the rivers. They are an important source of B3+ and Li+ to the rivers. The abnormally high contents of B3+ and Li+ in the Nalenggele and Wutumeiren Rivers also suggest that the geothermal source area may be a future target for boron and lithium resources.

Utility of 222Rn as a passive tracer of subglacial distributed system drainage

NASA Astrophysics Data System (ADS)

Linhoff, Benjamin S.; Charette, Matthew A.; Nienow, Peter W.; Wadham, Jemma L.; Tedstone, Andrew J.; Cowton, Thomas

2017-03-01

Water flow beneath the Greenland Ice Sheet (GrIS) has been shown to include slow-inefficient (distributed) and fast-efficient (channelized) drainage systems, in response to meltwater delivery to the bed via both moulins and surface lake drainage. This partitioning between channelized and distributed drainage systems is difficult to quantify yet it plays an important role in bulk meltwater chemistry and glacial velocity, and thus subglacial erosion. Radon-222, which is continuously produced via the decay of 226Ra, accumulates in meltwater that has interacted with rock and sediment. Hence, elevated concentrations of 222Rn should be indicative of meltwater that has flowed through a distributed drainage system network. In the spring and summer of 2011 and 2012, we made hourly 222Rn measurements in the proglacial river of a large outlet glacier of the GrIS (Leverett Glacier, SW Greenland). Radon-222 activities were highest in the early melt season (10-15 dpm L-1), decreasing by a factor of 2-5 (3-5 dpm L-1) following the onset of widespread surface melt. Using a 222Rn mass balance model, we estimate that, on average, greater than 90% of the river 222Rn was sourced from distributed system meltwater. The distributed system 222Rn flux varied on diurnal, weekly, and seasonal time scales with highest fluxes generally occurring on the falling limb of the hydrograph and during expansion of the channelized drainage system. Using laboratory based estimates of distributed system 222Rn, the distributed system water flux generally ranged between 1-5% of the total proglacial river discharge for both seasons. This study provides a promising new method for hydrograph separation in glacial watersheds and for estimating the timing and magnitude of distributed system fluxes expelled at ice sheet margins.

Monitoring Freeze-Thaw States in the Pan-Arctic: Application of Microwave Remote Sensing to Monitoring Hydrologic and Ecological Processes

NASA Astrophysics Data System (ADS)

McDonald, K. C.; Kimball, J. S.

2004-12-01

The transition of the landscape between predominantly frozen and non-frozen conditions in seasonally frozen environments impacts climate, hydrological, ecological and biogeochemical processes profoundly. Satellite microwave remote sensing is uniquely capable of detecting and monitoring a range of related biophysical processes associated with the measurement of landscape freeze/thaw status. We present the development, physical basis, current techniques and selected hydrological applications of satellite-borne microwave remote sensing of landscape freeze/thaw states for the terrestrial cryosphere. Major landscape hydrological processes embracing the remotely-sensed freeze/thaw signal include timing and spatial dynamics of seasonal snowmelt and associated soil thaw, runoff generation and flooding, ice breakup in large rivers and lakes, and timing and length of vegetation growing seasons and associated productivity and trace gas exchange. Employing both active and passive microwave sensors, we apply a selection of temporal change classification algorithms to examine a variety of hydrologic processes. We investigate contemporaneous and retrospective applications of the QuikSCAT scatterometer, and the SSM/I and SMMR radiometers to this end. Results illustrate the strong correspondence between regional thawing, seasonal ice break up for rivers, and the springtime pulse in river flow. We present the physical principles of microwave sensitivity to landscape freeze/thaw state, recent progress in applying these principles toward satellite remote sensing of freeze/thaw processes over broad regions, and potential for future global monitoring of this significant phenomenon of the global cryosphere. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, and at the University of Montana, Missoula, under contract to the National Aeronautics and Space Administration.

Bedload entrainment in low-gradient paraglacial coastal rivers of Maine, U.S.A.: Implications for habitat restoration

NASA Astrophysics Data System (ADS)

Snyder, Noah P.; Castele, Michael R.; Wright, Jed R.

2009-02-01

The rivers of coastal Maine flow through mainstem lakes and long low-gradient reaches that break the continuum of bedload transport expected in nonparaglacial landscapes. Stream erosion of glacial deposits supplies coarse sediment to these systems. The land use history includes intensive timber harvest and associated dam construction, which may have altered the frequency of substrate-mobilizing events. These watersheds are vital habitat for the last remaining wild anadromous Atlantic salmon in the United States. Future adjustments in channel morphology and habitat quality (via natural stream processes or restoration projects) depend on erosion, transport, and deposition of coarse sediment. These factors motivate our study of competence at four sites in the Sheepscot and Narraguagus watersheds. Three of the four sites behaved roughly similarly, with particle entrainment during intervals that include winter ice and spring flood conditions, and relatively minor bed mobilization during moderate floods in the summer and fall (with a recurrence interval of 2-3 years). The fourth site, on the Sheepscot River mainstem, exhibits more vigorous entrainment of marked particles and more complex three-dimensional channel morphology. This contrast is partially due to local geomorphic conditions that favor high shear stresses (particularly relatively steep gradient), but also likely to nourishment of the bedload saltation system by recruitment from an eroding glacial deposit upstream. Our results suggest that the frequency and magnitude of bedload transport are reach specific, depending on factors including local channel geometry, upstream sediment supply and transport, and formation of anchor ice. This presents a challenge for stream practitioners in this region: different reaches may require contrasting management strategies. Our results underscore the importance of understanding channel processes at a given site and assessing conditions upstream and downstream as a prerequisite for conducting habitat restoration projects.

Stratigraphic Sedimentary Environmental Change of the Mount Bruce Supergroup, Beasley River Area, Southern Pilbara, Western Australia

NASA Astrophysics Data System (ADS)

Komure, M.; Kiyokawa, S.; Ikehara, M.; Tsutsumi, Y.; Horie, K.

2005-12-01

The Mount Bruce Supergroup is deposited from Late Archaean to Early Proterozoic in the Pilbara craton, Western Australia. It is filed the information of the period that changes from the Late Archean to the Early Proterozoic, and is the key sequences which could reconstruct the sedimentary environment because of its low metamorphic grade. The evidence of early Proterozoic global ice age as the glacial sediment is reported in this uppermost group (Martin 1999). In this study, we focus the lithological changes of the Mount Bruce Supergroup at the Beasley River - Rocklea Dome area in the Southern Pilbara. Along the Beasley River, this supergroup distributes more than 10000m thick with 5 billion years sequences, and is divided into three groups. The Fortescue Group is identified with the flood basalt to the Shallow marine or the non-marine sediment, the middle Hamersley Group rich in the banded iron formation and the acidic volcanic rock and the upper Turee Creek Group mainly of the Shallow marine sediment. Here we focused origin of the sandstone in each group, especially in the Meteorite Bore Member of Turee Creek Formation which is identified as the early snowball earth events. At the matrix of the diamictite of the Meteorite Bore Member, Origin of diamictite matrix in the Turee Creek Group sediment by the U-Pb detrital zircon geochronology by CHIME and SHRIMP2. The zircon ages points between 2.7Ga and 2.4Ga. In addtion from this matrix, TOC value indicate 0.1-0.05%, the delta 13 C value is -30--20 par mil. These evidence suggested that the organic activity might take place at during ice age.

Environmental conditions and biological community of the Penzhina and Talovka hypertidal estuary (northwest Kamchatka) in the ice-free season

NASA Astrophysics Data System (ADS)

Koval, M. V.; Gorin, S. L.; Romanenko, F. A.; Lepskaya, E. V.; Polyakova, A. A.; Galyamov, R. A.; Esin, E. V.

2017-07-01

New data on the abiotic conditions; species composition; abundance, distribution, and migrations of fauna; and feeding interactions in an estuary ecosystem were obtained during expeditions in the mouths of Penzhina and Talovka rivers (northwest Kamchatka). It is revealed that in the ice-free season, the hydrological regime of the estuary is determined by seasonal fluctuations of river runoff, as well as fortnightly and daily variation of tides. The estuary is characterized by hypertidal fluctuations (up to 10-12 m); strong reverse flows (up to 1.0-1.5 m/s), considerable tidal variations in salinity (from 0 to 6-9‰ at the river boundary and from 6-8 to 14-16‰ at the offshore boundary), and high water turbidity (up to 1 000 NTU or more). Based on the spatial structure of the community, three ecological zones with mobile boundaries are distinguished: freshwater (salinity 0-0.1‰), estuarine (0-12.3‰), and neritic (11.2-18.9‰). High turbidity prevents the development of phytoplankton in the estuarine zone (EZ), and the local benthic community is significantly depleted due to the desalination and wide spread of aleuritic silts. Neritic copepods and nektobenthic brackish- water crustaceans generate the maximum abundance and biomass here. The species that have adapted to the local extreme hydrologic conditions dominate and form the basis of the estuarine food chain. Dominant among the EZ vertebrates are such groups as anadromous fishes (smelts, pacific salmons, charrs, and sticklebacks); waterfowl (terns, kittiwakes, cormorants, fulmars, puffins, guillemots, auklets, and wadepipers); and predatory marine mammals (larga, ringed seal, bearded seal, and white whale). The total abundance and biomass of these animals are much higher in the pelagic EZ in comparison to neighboring zones.

A Research Plan for Assessing the Power and Energy Capability of a River Network Under an Integrated Wind/Hydro-Electric Dispatchable Regime

NASA Astrophysics Data System (ADS)

Banka, John Czeslaw

The world strives for more clean and renewable energy, but the amount of dispatchable energy in river networks is not accurately known and difficult to assess. When wind is integrated with water, the dispatchable yield can be greatly increased, but the uncertainty of the wind further degrades predictability. This thesis demonstrates how simulating the flows is a river network integrated with wind over a long time domain yields a solution. Time-shifting the freshet and pumped storage will ameliorate the seasonal summer drought; the risk of ice jams and uncontrolled flooding is reduced. An artificial market eliminates the issue of surplus energy from wind at night. Furthermore, this thesis shows how the necessary infrastructure can be built to accomplish the goals of the intended research. While specific to Northern Ontario and sensitive to the lives of the Native peoples living there, it indicates where the research might be applicable elsewhere in the world.

Applications of Experimental Suomi-NPP VIIRS Flood Inundation Maps in Operational Flood Forecasting

NASA Astrophysics Data System (ADS)

Deweese, M. M.

2017-12-01

Flooding is the most costly natural disaster across the globe. In 2016 flooding caused more fatalities than any other natural disaster in the United States. The U.S. National Weather Service (NWS) is mandated to forecast rivers for the protection of life and property and the enhancement of the national economy. Since 2014, the NWS North Central River Forecast Center has utilized experimental near real time flood mapping products from the JPSS Suomi-NPP VIIRS satellite. These products have been demonstrated to provide reliable and high value information for forecasters in ice jam and snowmelt flooding in data sparse regions of the northern plains. In addition, they have proved valuable in rainfall induced flooding within the upper Mississippi River basin. Aerial photography and ground observations have validated the accuracy of the products. Examples are provided from numerous flooding events to demonstrate the operational application of this satellite derived information as a remotely sensed observational data source and it's utility in real time flood forecasting.

Climate-driven shifts in quantity and seasonality of river discharge over the past 1000 years from the hydrographic apex of North America

NASA Astrophysics Data System (ADS)

Wolfe, Brent B.; Hall, Roland I.; Edwards, Thomas W. D.; Jarvis, Suzanne R.; Sinnatamby, R. Niloshini; Yi, Yi; Johnston, John W.

2008-12-01

Runoff generated from high elevations is the primary source of freshwater for western North America, yet this critical resource is managed on the basis of short instrumental records that capture an insufficient range of climatic conditions. Here we probe the effects of climate change over the past ~1000 years on river discharge in the upper Mackenzie River system based on paleoenvironmental information from the Peace-Athabasca Delta. The delta landscape responds to hydroclimatic changes with marked variability, while Lake Athabasca level appears to directly monitor overall water availability. The latter fluctuated systematically over the past millennium, with the highest levels occurring in concert with maximum glacier extent during the Little Ice Age, and the lowest during the 11th century, prior to medieval glacier expansion. Recent climate-driven hydrological change appears to be on a trajectory to even lower levels as high-elevation snow and glacier meltwater contributions both continue to decline.

Aral Sea in Uzbekastan seen from STS-59

NASA Technical Reports Server (NTRS)

1994-01-01

View northeastward across Uzbekastan to the partly-ice-covered Aral Sea and Kazakhstan. The irrigated fan-delta of the Amu Darya extends from the right side of the photograph to end in extensive salt flats at the south end of the sea. The Aral was the fourth-largest inland sea or lake in the world, until diversion and over-use of the river water for irrigation led, in this arid climate, to the sea's decline.

12. Photographic copy of historic photograph. Original snapshot print can ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. Photographic copy of historic photograph. Original snapshot print can be found in narrative reports of the Lower Souris Migratory Waterfowl Refuge for the 1930s, on file at the headquarters of the J. Clark Salyer National Wildlife Refuge, Upham, North Dakota. GATES OF DAM 320 ON APRIL 9, 1936 WITH ICE ON WATER 50 INCHES THICK - J. Clark Salyer National Wildlife Refuge, Dam 320, Along Lower Souris River, Kramer, Bottineau County, ND

Investigation of LANDSAT imagery on correlations between ore deposits and major shield structures in Finland

NASA Technical Reports Server (NTRS)

Tuominen, H. V. (Principal Investigator); Kuosmanen, V.

1976-01-01

The author has identified the following significant results. Based on tests, it is obvious that practically all major LANDSAT winter linears found are geologically significant features. Most of them are chains of bogs, lakes, rivers, and cultivated areas covered by ice and/or snow, i.e., unforested linear topographic lows. They need no explanation other than that they are extensive fracture zones of the basement.

Monitoring unrest in a subglacial volcano by combining thermal, meltwater conductivity and seismic signals: The Katla caldera, Iceland

NASA Astrophysics Data System (ADS)

Gudmundsson, Magnus T.; Hognadóttir, Þórdís; Vogfjord, Kristín; Magnusson, Eyjólfur; Reynolds, Hanna I.; Roberts, Matthew

2014-05-01

Highly active ice-covered volcanoes pose problems for some of the methods used for monitoring unrest associated with magma movements in the crust. Glacier surfaces are subjected to meteorological and seasonal fluctuations in elevation at time scales ranging from hours/days to years. Such fluctuations limit the applicability of inSAR and GPS, and in general the detection of crustal deformation signals. Nunataks provide sites for GPS bench marks but the seasonal fluctuations in ice cover elevation and subglacial water pressure generate associated fluctuations in observed ground deformation. The Katla caldera in south Iceland is filled with 400-700 m thick ice, has seasonal variations in surface elevation of ~10 m and basal water pressure variations suspected to be of the order of 1 MPa. Geothermal activity within the caldera is manifested as 15-20 depressions in the ice surface, typically 500-1000 m wide and 15-50 m deep. The depressions, also called ice cauldrons, are formed by geothermal melting at the base of the glacier. At some of these cauldrons meltwater collects at the glacier base and stored for some weeks or months before being drained in small outburst floods. At other cauldrons the meltwater at the base is drained away continuously, releasing geothermal waters into the rivers draining the glacier. The size and depth of the ice cauldrons in Katla has been monitored by regular overflights with a radar that measures surface elveation profiles along the flight lines. A time series of cauldron variations has been obtained since 1999. Over the same period semi-continuous records of electrical conductivity in rivers draining from the outlet glaciers from the caldera have been obtained. The data show variations in geothermal output and conductivity that broadly correlate with seismic activity. Most of the seismicity occurs at less than 2-3 km depth, in swarms consisting mostly of earthquakes of sizes <2.5-3. On a time scale of months- to-years, increases in seismicity are associated with increased geothermal activity. Two events (1999 and 2011) have occurred where cauldrons grew significantly or new were formed, leading to the release of significant amounts of meltwater from the glacier in larger outburst floods (peak discharge of few thousand m3/s). The 2011 flood swept away the bridge on the main road, causing disruption to transport along the south coast of Iceland. These events have not been properly explained, but they are clearly associated with increases in geothermal heat output and increased seismicity in the caldera. The association of these events with shallow magma migration is at present unclear but is one of the tasks FUTUREVOLC in 2012-2016 is to study these geothermal-seismicity-unrest linkages.

Movement of bull trout in the upper Jarbidge River watershed, Idaho and Nevada, 2008-09--A supplement to Open-File Report 2010-1033

USGS Publications Warehouse

Munz, Carrie S.; Allen, M. Brady; Connolly, Patrick J.

2011-01-01

We monitored bull trout (Salvelinus confluentus) in 2008 and 2009 as a continuation of our work in 2006 and 2007, which involved the tagging of 1,536 bull trout with passive integrated transponder (PIT) tags in the East Fork Jarbidge River and West Fork Jarbidge River and their tributaries in northeastern Nevada and southern Idaho. We installed PIT tag interrogation systems (PTISs) at established locations soon after ice-out, and maintained the PTISs in order to collect information on bull trout movements through December of each year. We observed a marked increase of movement in 2008 and 2009. Bull trout tagged in the uppermost portions of the East Fork Jarbidge River at altitudes greater than 2,100 meters moved to the confluence of the East Fork Jarbidge River and West Fork Jarbidge River in summer and autumn. Ten bull trout tagged upstream of the confluence of Pine Creek and the West Fork Jarbidge River moved downstream and then upstream in the East Fork Jarbidge River, and then past the PTIS at Murphy Hot Springs (river kilometer [rkm] 4.1). Two of these fish ascended Dave Creek, a tributary of the East Fork Jarbidge River, past the PTIS at rkm 0.4. One bull trout that was tagged at rkm 11 in Dave Creek on June 28, 2007 moved downstream to the confluence of the East Fork Jarbidge River and West Fork Jarbidge River (rkm 0) on July 28, 2007, and it was then detected in the West Fork Jarbidge River moving past our PTIS at rkm 15 on May 4, 2008. Combined, the extent and types of bull trout movements observed indicated that the primarily age-1 and age-2 bull trout that we tagged in 2006 and 2007 showed increased movement with age and evidence of a substantial amount of fluvial life history. The movements suggest strong connectivity between spawning areas and downstream mainstem areas, as well as between the East Fork Jarbidge River and West Fork Jarbidge River.

Reconstructions of the Weichselian ice sheet, a comparative study of a thermo-mechanical approach to GIA driven models.

NASA Astrophysics Data System (ADS)

Schmidt, Peter; Lund, Björn; Näslund, Jens-Ove; Fastook, James

2014-05-01

Observations of glacial isostatic adjustment (GIA) have been used both to study the mechanical properties of the Earth and to invert for Northern Hemisphere palaeo-ice-sheets. This is typically done by solving the sea-level equation using simplified scaling laws to control ice-sheet thickness. However, past ice-sheets can also be reconstructed based on thermo-mechanical modelling driven by palaeo-climate data, invoking simple analytical models to account for the Earth's response. Commonly, both approaches use dated geological markers to constrain the ice-sheet margin location. Irrespective of the approach, the resulting ice-sheet reconstruction depends on the earth response, although the interdependence between the ice model and the earth model differs and therefore the two types of reconstructions could provide complementary information on Earth properties. We compare a thermo-mechanical reconstruction of the Weichselian ice-sheet using the UMISM model (Näslund, 2010) to two GIA driven reconstructions, ANU (Lambeck et al., 2010) and ICE-5G (Peltier & Fairbanks, 2006), commonly used in GIA modelling. We evaluate the three reconstructions both in terms of ice-sheet configurations and predicted Fennoscandian surface deformation ICE-5G comprise the largest reconstructed ice-sheet whereas ANU and UMISM are more similar in volume and areal extent. Significant differences still exists between ANU and UMISM, especially during the final deglaciation phase. Prior to the final retreat of the ice-sheet, ICE-5G is displays a massive and more or less constant ice-sheet configuration, while both ANU and UMISM fluctuates with at times almost ice-free conditions, such as during MIS3. This results in ICE-5G being close to isostatic equilibrium at LGM, whereas ANU and UMISM are not. Hence, the pre-LGM evolution of the Weichselian ice-sheet needs to be considered in GIA studies. For example, perturbing the ANU or UMISM reconstructions we find that changes more recent than 36 kyr BP may change the predicted uplift velocities by more than 0.1 mm/yr, while changes more recent than 55 kyr BP may change the predicted uplift 10 kyr ago by more than 5 m. Despite their differences we find that all three reconstructions can equally well fit observations of the present day uplift in Fennoscandia, as well as the observed sea-level curve along the Ångerman river, Sweden, albeit with different optimal earth models. However, only for ANU can a single optimal earth model be determined as a bifurcation in the optimal viscosity arises from the generally faster present day rebound rates in ICE-5G and UMISM, resulting in a range of well-fitting earth models for the latter reconstructions. Studying models with a reasonable fit to observed present day uplift velocities we find general trends of over- and under-prediction, indicating that all three ice-sheet reconstructions need improvement. In general, all three reconstructions tend to over-predict the uplift rates in southwestern Fennoscandia, whereas over Finland ICE-5G generally over-predicts and ANU generally under-predicts the uplift rates. UMISM tend to under-predict the velocities over central to northern Sweden and similar trends can also be seen in ANU and ICE-5G.

Circumpolar patterns of ground-fast lake ice and landscape development

NASA Astrophysics Data System (ADS)

Bartsch, Annett; Pointner, Georg; Leibmann, Marina; Dvornikov, Yuri; Khomutov, Artem

2017-04-01

Shallow lakes in the Arctic are often associated with thermokarst processes which are characteristic for permafrost environments. They partially or completely freeze-up during winter time what can be observed from space using Synthetic Aperture Radar (SAR) data. Spatial patterns of ground-fast and floating ice relate to geomorphological and hydrological processes, but no circumpolar account of this phenomenon is currently available due to challenges when dealing with the varying observation geometry typical for SAR. An approach using ENVISAT ASAR Wide Swath data (approximately 120 m resolution) has been developed supported by bathymetric measurements in Siberia and eventually applied across the entire Arctic for late winter 2008. In total about 2 Million lake objects have been analyzed considering the boundaries of the Last Glacial Maximum, permafrost zones and soil organic carbon content. Distinct patterns of ground-fast lake ice fraction can be found across the Arctic. Clusters of variable fractions of ground-fast ice occur especially in Yedoma regions of Eastern Siberia and Alaska. This reflects the nature of thaw lake dynamics. Analyses of lake depth measurements from several sites (Alaskan North Slope, Richards Island in Canada, Yamal Peninsula and Lena Delta) suggest that the used method yields the potential to utilize ground-fast lake ice information over larger areas with respect to landscape development, but results need to be treated with care, specifically for larger lakes and along river courses. A combination of general lake features and ground-fast ice fraction may lead to an advanced understanding of landscape patterns and development. Ground-fast ice fraction information may support to some extent the identification of landscape units, for example areas of adjacent lakes with similar patterns (terraces) or areas with mixed ground-fast fractions which indicate different lake development stages. This work was supported by the Austrian Science Fund under Grant [I 1401] and the Russian Foundation for Basic Research Grant 13-05-91001-ANF-a (Joint Russian-Austrian project COLD-Yamal).