Silicon concentrations in UK surface waters

NASA Astrophysics Data System (ADS)

Neal, Colin; Neal, Margaret; Reynolds, Brian; Maberly, Stephen C.; May, Linda; Ferrier, Robert C.; Smith, Jennifer; Parker, Julie E.

2005-03-01

This paper describes the variations in silicon concentrations in UK waters for a wide range of catchment systems (near pristine, rural, and agricultural and urban impacted systems). The paper largely concerns silicon levels in streams, rivers and lakes based on extensive data collected as part of several research and monitoring initiatives of national and international standing. For a detailed study of an upland catchment in mid-Wales, information on atmospheric inputs and groundwater chemistries is provided to supply background information to cross link to the surface water chemistry. Several hundred streams/rivers and lakes are dealt with within the study, dealing with the main types of freshwater riverine and lacustrine environments. The streams/rivers vary from small ephemeral runoff to the major rivers of the UK. The geographical location of sites vary from local sites in mid-Wales, to regional studies across Scotland, to the major eastern UK rivers entering the North Sea and to acid sensitive upland sites across Wales, the English Lake District, Scotland and Northern Ireland. The surface waters range in silicon concentration from 0 to 19 mg-Si l -1 (average for individual sites vary between 0.7 and 7.6 mg-Si l -1) and there are some clear variations which link to two primary processes (1) the relative inputs of groundwaters enriched in silicon and near surface waters more depleted in silicon and (2) plankton uptake of silicon during the summer months under baseflow conditions. Thermodynamic analysis reveals that the waters are approximately saturated with respect to either quartz or chalcedony except for two circumstances when undersaturation occurs. Firstly, undersaturation occurs at pH less than 5.5 in the upland areas and this is because the waters are mainly sourced from the acidic organic soils which are depleted in inorganic minerals. Secondly, undersaturation occurs in the lowland rivers when biological activity is at its highest and this leads to

Estimating Sources and Fluxes of Dissolved and Particulate Organic Matter in UK Rivers

NASA Astrophysics Data System (ADS)

Adams, Jessica; Tipping, Edward; Quinton, John; Old, Gareth

2014-05-01

Over the past two centuries, pools and fluxes of carbon, nitrogen and phosphorus in UK ecosystems have been altered by intensification of agriculture, land use change and atmospheric pollution leading to acidification and eutrophication of surface waters. In addition to this, climate change is now also predicted to substantially impact these systems. The CEH Long Term Large Scale (LTLS) project therefore aims to simulate the pools and fluxes of carbon, nitrogen and phosphorus and their stoichiometry during the cycling process. Through the N14C model, simulations of the release of C, N and P through drainage water and erosion processes will be predicted using historical climate data, which will be tested using contemporary data. For present data, water from four UK catchments (Ribble, Wiltshire Avon, Conwy, Dee) were collected at the tidal limit of each river, which included a combination of high and low flow samples predicted using 5 day forecasts and local weather station data. These samples were filtered, centrifuged and sent to the NERC radiocarbon facility for analysis by accelerator mass spectrometry (AMS) to obtain both PO14C and DO14C data. Radiocarbon enables a unique and dynamic way of estimating long term turnover rates of organic matter, and has proven to be an invaluable tool for measuring upland terrestrial and aquatic systems. It has however, been scarcely used in larger, lowland river systems. Since the riverine organic matter captured is likely to have originated from terrestrial and riparian sources, the radiocarbon data will be a rigorous test of the model's ability to simulate the coupling of erosion and leaching processes, and stoichiometric relationships between C:N:P.

Approaches to restoration of oak forests on farmed lowlands of the Mississippi River and its tributaries

Treesearch

Emile S. Gardiner; Daniel C. Dey; John A. Stanturf; Brian Roy Lockhart

2010-01-01

The lowlands associated with the Mississippi River and its tributaries historically supported extensive broadleaf forests that were particularly rich in oak (Quercus spp.) species. Beginning in the 1700s, deforestation for agriculture substantially reduced the extent of the original forest, and fragmented the remainder into small parcels. More...

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.

Quantification of the impact of macrophytes on oxygen dynamics and nitrogen retention in a vegetated lowland river

NASA Astrophysics Data System (ADS)

Desmet, N. J. S.; Van Belleghem, S.; Seuntjens, P.; Bouma, T. J.; Buis, K.; Meire, P.

When macrophytes are growing in the river, the vegetation induces substantial changes to the water quality. Some effects are the result of direct interactions, such as photosynthetic activity or nutrient uptake, whereas others may be attributed to indirect effects of the water plants on hydrodynamics and river processes. This research focused on the direct effect of macrophytes on oxygen dynamics and nutrient cycling. Discharge, macrophyte biomass density, basic water quality, dissolved oxygen and nutrient concentrations were in situ monitored throughout the year in a lowland river (Nete catchment, Belgium). In addition, various processes were investigated in more detail in multiple ex situ experiments. The field and aquaria measurement results clearly demonstrated that aquatic plants can exert considerable impact on dissolved oxygen dynamics in a lowland river. When the river was dominated by macrophytes, dissolved oxygen concentrations varied from 5 to 10 mg l -1. Considering nutrient retention, it was shown that the investigated in-stream macrophytes could take up dissolved inorganic nitrogen (DIN) from the water column at rates of 33-50 mg N kgdry matter-1 h. And DIN fluxes towards the vegetation were found to vary from 0.03 to 0.19 g N ha -1 h -1 in spring and summer. Compared to the measured changes in DIN load over the river stretch, it means that about 3-13% of the DIN retention could be attributed to direct nitrogen uptake from the water by macrophytes. Yet, the role of macrophytes in rivers should not be underrated as aquatic vegetation also exerts considerable indirect effects that may have a greater impact than the direct fixation of nutrients into the plant biomass.

Duration and Frequency Analysis of Lowland Flooding in Western Murfreesboro, Rutherford County, Tennessee, 1998-2000

USGS Publications Warehouse

Law, George S.

2002-01-01

Periodic flooding occurs at lowlands and sinkholes in and adjacent to the flood plain of the West Fork Stones River in the western part of Murfreesboro, Tennessee. Flooding in this area commonly occurs during the winter months from December through March. The maximum water level that flood waters will reach in a lowland or sinkhole is controlled by the elevation of the land surrounding the site or the overflow outlet. Maximum water levels, independent of overflow from the river, were estimated to be reached in lowlands and sinkholes in the study area every 1 to 4 years. Minor overflow from the West Fork Stones River (less than 1 foot in depth) into the study area has been estimated to occur every 10 to 20 years. Moderate overflow from the river (1 to 2 feet in depth) occurs on average every 20 to 50 years, while major river overflow (in excess of 2 feet in depth) can be expected every 50 years. Rainfall information for the area, and streamflow and water-level measurements from the West Fork Stones River, lowlands, sinkholes, caves, and wells in the study area were used to develop a flood-prone area map, independent of overflow from the river, for the study area. Water-level duration and frequency relations, independent of overflow from the river, were estimated for several lowlands, sinkholes, and wells in the study area. These relations are used to characterize flooding in lowland areas of western Murfreesboro, Rutherford County, Tennessee.

Fate of polar organic trace compounds infiltrating into an alluvial aquifer from an urban lowland river

NASA Astrophysics Data System (ADS)

Schaper, J. L.; Popp, A. L.; Meinikmann, K.; Shanafield, M.; Banks, E.; Putschew, A.; Lewandowski, J.; Nuetzmann, G.

2016-12-01

High loads of polar organic trace compounds (TrOCs) are frequently detected in urban surface waters threatening both, ecosystem functioning and local drinking water supply. Here we investigate the fate and turnover rate of 17 TrOCs infiltrating from the urban river Erpe into the adjacent alluvial aquifer. River Erpe is a lowland stream in Berlin, Germany that receives up to 80 % of its discharge from a municipal wastewater treatment plant (WWTP) thus containing TrOCs in the µg/L range. To this end, a horizontal piezometer transect extending into the alluvial plane as well as a vertical piezometer nest in the riverbed were installed and sampled in June and July 2016. Within the horizontal transect, redox condition remained aerobic resulting in attenuation rates of up to 25 % for benzotriazol, Carbamazepine, metoprolol and 4 - formylaminoantipyrin. Concentrations of bezafibrate and acesulfame increased although the concentrations of more persistent compounds such as primidone and gabapentin, remained relatively constant. Within the vertical piezometer nest, Fe(II) concentrations increased with depth, allowing for a more rapid turnover of Sulfamethoxazole, but also inhibiting turnover of other compounds such as, benzotriazol, metoprolol and Valsartan. In contrast to previous studies undertaken in more mountainous settings, alluvial attenuation rates at River Erpe were profoundly different. We attribute these findings to both, hydrological characteristics of lowland rivers as well as to the high amounts of labile organic carbon originating from the WWTP effluent. This work further demonstrates that the fate of TrOCs in gaining aquifers adjacent to urban streams is highly complex and demands much more research.

Does reintroducing large wood influence the hydraulic landscape of a lowland river system?

NASA Astrophysics Data System (ADS)

Matheson, Adrian; Thoms, Martin; Reid, Michael

2017-09-01

Our understanding of the effectiveness of reintroduced large wood for restoration is largely based on studies from high energy river systems. By contrast, few studies of the effectiveness of reintroducing large wood have been undertaken on large, low energy, lowland river systems: river systems where large wood is a significant physical feature on the in-channel environment. This study investigated the effect of reintroduced large wood on the hydraulic landscape of the Barwon-Darling River, Australia, at low flows. To achieve this, the study compared three hydraulic landscapes of replicated reference (naturally wooded), control (unwooded,) and managed (wood reintroduced) treatments on three low flow periods. These time periods were prior to the reintroduction of large wood to managed reaches; several months after the reintroduction of large wood into the managed reaches; and then more than four years after wood reintroduction following several large flood events. Hydraulic landscapes of reaches were characterised using a range of spatial measures calculated from velocity measurements taken with a boat-mounted Acoustic Doppler Profiler. We hypothesised that reintroduced large wood would increase the diversity of the hydraulic landscape at low flows and that managed reaches would be more similar to the reference reaches. Our results suggest that the reintroduction of large wood did not significantly change the character of the hydraulic landscape at the reach scale after several months (p = 0.16) or several years (p = 0.29). Overall, the character of the hydraulic landscape in the managed reaches was more similar to the hydraulic landscape of the control reaches than the hydraulic landscape of the reference reaches, at low flows. Some variability in the hydraulic landscapes was detected over time, and this may reflect reworking of riverbed sediments and sensitivity to variation in discharge. The lack of a response in the low flow hydraulic landscape to the

Modelling the future impacts of climate and land-use change on suspended sediment transport in the River Thames (UK)

NASA Astrophysics Data System (ADS)

Bussi, Gianbattista; Dadson, Simon J.; Prudhomme, Christel; Whitehead, Paul G.

2016-11-01

The effects of climate change and variability on river flows have been widely studied. However the impacts of such changes on sediment transport have received comparatively little attention. In part this is because modelling sediment production and transport processes introduces additional uncertainty, but it also results from the fact that, alongside the climate change signal, there have been and are projected to be significant changes in land cover which strongly affect sediment-related processes. Here we assess the impact of a range of climatic variations and land covers on the River Thames catchment (UK). We first calculate a response of the system to climatic stressors (average precipitation, average temperature and increase in extreme precipitation) and land-cover stressors (change in the extent of arable land). To do this we use an ensemble of INCA hydrological and sediment behavioural models. The resulting system response, which reveals the nature of interactions between the driving factors, is then compared with climate projections originating from the UKCP09 assessment (UK Climate Projections 2009) to evaluate the likelihood of the range of projected outcomes. The results show that climate and land cover each exert an individual control on sediment transport. Their effects vary depending on the land use and on the level of projected climate change. The suspended sediment yield of the River Thames in its lowermost reach is expected to change by -4% (-16% to +13%, confidence interval, p = 0.95) under the A1FI emission scenario for the 2030s, although these figures could be substantially altered by an increase in extreme precipitation, which could raise the suspended sediment yield up to an additional +10%. A 70% increase in the extension of the arable land is projected to increase sediment yield by around 12% in the lowland reaches. A 50% reduction is projected to decrease sediment yield by around 13%.

Ecohydrology of an Embanked Lowland UK River Meadow and the Effects of Embankment Removal

NASA Astrophysics Data System (ADS)

Clilverd, H.; Thompson, J.; Sayer, C.; Heppell, K.; Axmacher, J.

2012-12-01

Pristine riparian and floodplain ecosystems are in a state of dynamic balance due to the regular floods that continuously reshape river channels and their banks, and transport water, sediment and nutrients onto the floodplain. However, the natural flow regime of many rivers has been altered by channelization and artificial embankments designed to protect agricultural and urban developments from flooding. This has had a lasting impact on the hydrological characteristics of floodplain ecosystems and the biological communities that inhabit them. Floodplain restoration, through embankment removal and the reconfiguration of river channels, is now being increasingly employed to re-establish river-floodplain connections and assist the recovery of lost or declining species. In order to manage a river restoration site for plant biodiversity, it is necessary to understand the physical and nutritional status of the root environment. We conducted fine scale (10 × 10 m) botanical and chemical sampling on a 3 ha embanked grassland meadow in Norfolk (Eastern England) and assessed the spatial pattern of plant communities in relation to soil physicochemical conditions. Continuous measurements of groundwater depth and river stage were collectively used to determine changes in the hydrological regime following embankment-removal. Prior to the restoration the meadow plant community was dominated by Holcus lanatus, Ranunculus repens and Agrostis stolonifera. Species richness was fairly low (mean: 8 spp. per m2), and indices of alpha-diversity suggest low heterogeneity of the plant assemblages (mean values for Shannon's Diversity and 1/Simpson's Diversity = 1.4 and 3.4, respectively). Top soils were moderately fertile, with mean respective Olsen P and plant available potassium concentrations of 9.1 mg P kg-1and 1.6 mg K+g-1. Plant available ammonium and nitrate concentrations were on average 31.7 mg NH4+-N kg-1 and 2.8 mg NO3--N kg-1, respectively. River water was enriched in nitrate

Flank collapse at Mount Wrangell, Alaska, recorded by volcanic mass-flow deposits in the Copper River lowland

USGS Publications Warehouse

Waythomas, C.F.; Wallace, K.L.

2002-01-01

An areally extensive volcanic mass-flow deposit of Pleistocene age, known as the Chetaslina volcanic mass-flow deposit, is a prominent and visually striking deposit in the southeastern Copper River lowland of south-central Alaska. The mass-flow deposit consists of a diverse mixture of colorful, variably altered volcanic rocks, lahar deposits, glaciolacustrine diamicton, and till that record a major flank collapse on the southwest flank of Mount Wrangell. The deposit is well exposed near its presumed source, and thick, continuous, stratigraphic exposures have permitted us to study its sedimentary characteristics as a means of better understanding the origin, significance, and evolution of the deposit. Deposits of the Chetaslina volcanic mass flow in the Chetaslina River drainage are primary debris-avalanche deposits and consist of two principal facies types, a near-source block facies and a distal mixed facies. The block facies is composed entirely of block-supported, shattered and fractured blocks with individual blocks up to 40 m in diameter. The mixed facies consists of block-sized particles in a matrix of poorly sorted rock rubble, sand, and silt generated by the comminution of larger blocks. Deposits of the Chetaslina volcanic mass flow exposed along the Copper, Tonsina, and Chitina rivers are debris-flow deposits that evolved from the debris-avalanche component of the flow and from erosion and entrainment of local glacial and glaciolacustrine diamicton in the Copper River lowland. The debris-flow deposits were probably generated through mixing of the distal debris avalanche with the ancestral Copper River, or through breaching of a debris-avalanche dam across the ancestral river. The distribution of facies types and major-element chemistry of clasts in the deposit indicate that its source was an ancestral volcanic edifice, informally known as the Chetaslina vent, on the southwest side of Mount Wrangell. A major sector collapse of the Chetaslina vent initiated

New insights into hydrochemical processes in lowland river systems gained from in situ, high-resolution monitoring

NASA Astrophysics Data System (ADS)

Wade, Andrew; Palmer-Felgate, Elizabeth; Halliday, Sarah; Skeffington, Richard; Loewenthal, Matthew; Jarvie, Helen; Bowes, Michael; Greenway, Gillian; Haswell, Stephen; Bell, Ian; Joly, Etienne; Fallatah, Ahmed; Neal, Colin; Williams, Richard; Gozzard, Emma; Newman, Jonathan

2013-04-01

This work focuses on the insights obtained from in situ, high-resolution hydrochemical monitoring in three lowland UK catchments experiencing different levels of nutrient enrichment. Between November 2009 and February 2012, the upper River Kennet, the River Enborne and The Cut, all located within the Thames basin, southeast England, were instrumented with in situ analytical equipment to make hourly measurements of a range of hydrochemical determinands. The upper River Kennet is a rural catchment with limited effluent inputs above the selected monitoring point. The River Enborne is a rural catchment, impacted by agricultural runoff, and septic tank and sewage treatment works (STWs) discharges. The Cut is a highly urbanised system significantly affected by STW discharges. On the upper River Kennet and the River Enborne hourly measurements of Total Reactive Phosphorus (TRP) were made using a Systea Micromac C. In addition on the River Enborne, a Hach Lange Nitratax was used to measure nitrate (NO3). On The Cut both Total P and TRP were measured using a Hach Lange Phosphax Sigma. At all stations nutrient monitoring was supplemented with hourly pH, chlorophyll, dissolved oxygen, conductivity, turbidity and water temperature using YSI 6600 Multi-parameter sondes. Instream hydrochemical dynamics were investigated using non-stationary time-series analysis techniques. The results reveal complex nutrient dynamics, with diurnal patterns which exhibit seasonal changes in phase and amplitude, and are influenced by flow conditions, shading and nutrient sources. On the River Enborne a marked diurnal cycle was present within the streamwater NO3 time-series. The cycle was strongest in the spring before riparian shading developed. At times of low flow a two peak diurnal cycle was also evident in the streamwater NO3 time-series. The reduction in diurnal NO3 processing after the development of riparian shading was also accompanied by a marked drop in dissolved oxygen at this time. The

Long Term Large Scale river nutrient changes across the UK

NASA Astrophysics Data System (ADS)

Bell, Victoria; Naden, Pam; Tipping, Ed; Davies, Helen; Davies, Jessica; Dragosits, Ulli; Muhammed, Shibu; Quinton, John; Stuart, Marianne; Whitmore, Andy; Wu, Lianhai

2017-04-01

During recent decades and centuries, pools and fluxes of Carbon, Nitrogen and Phosphorus (C, N and P) in UK rivers and ecosystems have been transformed by the spread and fertiliser-based intensification of agriculture (necessary to sustain human populations), by atmospheric pollution, by human waste (rising in line with population growth), and now by climate change. The principal objective of the UK's NERC-funded Macronutrients LTLS research project has been to account for observable terrestrial and aquatic pools, concentrations and fluxes of C, N and P on the basis of past inputs, biotic and abiotic interactions, and transport processes. More specifically, over the last 200 years, what have been the temporal responses of plant and soil nutrient pools in different UK catchments to nutrient enrichment, and what have been the consequent effects on nutrient transfers from land to the atmosphere, freshwaters and estuaries? The work described here addresses the second question by providing an integrated quantitative description of the interlinked land and water pools and annual fluxes of C, N and P for UK catchments over time. A national-scale modelling environment has been developed, combining simple physically-based gridded models that can be parameterised using recent observations before application to long timescales. The LTLS Integrated Model (LTLS-IM) uses readily-available driving data (climate, land-use, nutrient inputs, topography), and model estimates of both terrestrial and freshwater nutrient loads have been compared with measurements from sites across the UK. Here, the focus is on the freshwater nutrient component of the LTLS-IM, but the terrestrial nutrient inputs required for this are provided by models of nutrient processes in semi-natural and agricultural systems, and from simple models of nutrients arising from human waste. In the freshwater model, lateral routing of dissolved and particulate nutrients and within-river processing such as

Hydrochemical processes in lowland rivers: insights from in situ, high-resolution monitoring

NASA Astrophysics Data System (ADS)

Wade, A. J.; Palmer-Felgate, E. J.; Halliday, S. J.; Skeffington, R. A.; Loewenthal, M.; Jarvie, H. P.; Bowes, M. J.; Greenway, G. M.; Haswell, S. J.; Bell, I. M.; Joly, E.; Fallatah, A.; Neal, C.; Williams, R. J.; Gozzard, E.; Newman, J. R.

2012-11-01

This paper introduces new insights into the hydrochemical functioning of lowland river systems using field-based spectrophotometric and electrode technologies. The streamwater concentrations of nitrogen species and phosphorus fractions were measured at hourly intervals on a continuous basis at two contrasting sites on tributaries of the River Thames - one draining a rural catchment, the River Enborne, and one draining a more urban system, The Cut. The measurements complement those from an existing network of multi-parameter water quality sondes maintained across the Thames catchment and weekly monitoring based on grab samples. The results of the sub-daily monitoring show that streamwater phosphorus concentrations display highly complex dynamics under storm conditions dependent on the antecedent catchment wetness, and that diurnal phosphorus and nitrogen cycles occur under low flow conditions. The diurnal patterns highlight the dominance of sewage inputs in controlling the streamwater phosphorus and nitrogen concentrations at low flows, even at a distance of 7 km from the nearest sewage treatment works in the rural River Enborne. The time of sample collection is important when judging water quality against ecological thresholds or standards. An exhaustion of the supply of phosphorus from diffuse and multiple septic tank sources during storm events was evident and load estimation was not improved by sub-daily monitoring beyond that achieved by daily sampling because of the eventual reduction in the phosphorus mass entering the stream during events. The results highlight the utility of sub-daily water quality measurements and the discussion considers the practicalities and challenges of in situ, sub-daily monitoring.

Tracing dissolved organic carbon and trihalomethane formation potential between source water and finished drinking water at a lowland and an upland UK catchment.

PubMed

Brooks, Emma; Freeman, Christopher; Gough, Rachel; Holliman, Peter J

2015-12-15

Rising dissolved organic carbon (DOC) concentrations in many upland UK catchments represents a challenge for drinking water companies, in particular due to the role of DOC as a precursor in the formation of trihalomethanes (THMs). Whereas traditionally, the response of drinking water companies has been focussed on treatment processes, increasingly, efforts have been made to better understanding the role of land use and catchment processes in affecting drinking water quality. In this study, water quality, including DOC and THM formation potential (THMFP) was assessed between the water source and finished drinking water at an upland and a lowland catchment. Surprisingly, the lowland catchment showed much higher reservoir DOC concentrations apparently due to the influence of a fen within the catchment from where a major reservoir inflow stream originated. Seasonal variations in water quality were observed, driving changes in THMFP. However, the reservoirs in both catchments appeared to dampen these temporal fluctuations. Treatment process applied in the 2 catchments were adapted to reservoir water quality with much higher DOC and THMFP removal rates observed at the lowland water treatment works where coagulation-flocculation was applied. However, selectivity during this DOC removal stage also appeared to increase the proportion of brominated THMs produced. Copyright © 2015. Published by Elsevier B.V.

Geology and Hydrology Drive Benthic Fungal Community Structure in a Lowland River System

NASA Astrophysics Data System (ADS)

Mansour, I.; Heppell, C. M.; McKew, B.; Dumbrell, A.; Whitby, C. B.; Veresoglou, S.; Leung, G.; Binley, A. M.; Lansdown, K.; Trimmer, M.; Olde, L.; Rillig, M.

2017-12-01

Despite their essential roles in ecosystem functioning, exceptionally little is known about fungal communities and the ecological processes regulating their structure. This is particularly true for riverine ecosystems, where almost nothing about the diversity of their fungal communities is known. In this field study, benthic sediment samples and surface water samples were collected seasonally from lowland rivers (Hampshire Avon catchment, UK) underlain by three distinct parent geologies (clay, Greensand and Chalk), across a hydrological gradient of baseflow index ranging from 0.23 to 0.95. Fungal communities were assessed using high-throughput sequencing and community data were analyzed via ordination, variance partitioning and indicator species analysis. We found that distinct fungal communities inhabited the benthic sediments of the differing geologies. Clay sediments were dominated by the yeast Cryptococcus podzolicus, the hyphomycete Pseudeuotium hygrophilum, Mortierella, and unidentified fungi in the class Sordariomycetes - the latter two also common within Greensand sediments along with seasonal spikes in Rhizophydium littoreum, a parasite of green algae. An unidentified fungus from the phylum Ascomycota was numerically dominant at all chalk sites and across all seasons. Spatial variables explained only a negligible proportion of variance between communities, indicating that environmental and biotic processes drive the differences between the observed fungal communities rather than purely spatial mechanisms (e.g. stochastic processes). Season was a highly significant predictor of community structure (p=0.005) and baseflow index explained some of the variance within the fungal community data across seasons. This study demonstrates that deterministic rather than stochastic processes are important for structuring lotic fungal communities, and, for the first time, shows that underlying geology and associated differences in hydrology are drivers of fungal

Hypoxia, Blackwater and Fish Kills: Experimental Lethal Oxygen Thresholds in Juvenile Predatory Lowland River Fishes

PubMed Central

Small, Kade; Kopf, R. Keller; Watts, Robyn J.; Howitt, Julia

2014-01-01

Hypoxia represents a growing threat to biodiversity in freshwater ecosystems. Here, aquatic surface respiration (ASR) and oxygen thresholds required for survival in freshwater and simulated blackwater are evaluated for four lowland river fishes native to the Murray-Darling Basin (MDB), Australia. Juvenile stages of predatory species including golden perch Macquaria ambigua, silver perch Bidyanus bidyanus, Murray cod Maccullochella peelii, and eel-tailed catfish Tandanus tandanus were exposed to experimental conditions of nitrogen-induced hypoxia in freshwater and hypoxic blackwater simulations using dried river red gum Eucalyptus camaldulensis leaf litter. Australia's largest freshwater fish, M. peelii, was the most sensitive to hypoxia but given that we evaluated tolerances of juveniles (0.99±0.04 g; mean mass ±SE), the low tolerance of this species could not be attributed to its large maximum attainable body mass (>100,000 g). Concentrations of dissolved oxygen causing 50% mortality (LC50) in freshwater ranged from 0.25±0.06 mg l−1 in T. tandanus to 1.58±0.01 mg l−1 in M. peelii over 48 h at 25–26°C. Logistic models predicted that first mortalities may start at oxygen concentrations ranging from 2.4 mg l−1 to 3.1 mg l−1 in T. tandanus and M. peelii respectively within blackwater simulations. Aquatic surface respiration preceded mortality and this behaviour is documented here for the first time in juveniles of all four species. Despite the natural occurrence of hypoxia and blackwater events in lowland rivers of the MDB, juvenile stages of these large-bodied predators are vulnerable to mortality induced by low oxygen concentration and water chemistry changes associated with the decomposition of organic material. Given the extent of natural flow regime alteration and climate change predictions of rising temperatures and more severe drought and flooding, acute episodes of hypoxia may represent an underappreciated risk to riverine fish communities. PMID

Hypoxia, blackwater and fish kills: experimental lethal oxygen thresholds in juvenile predatory lowland river fishes.

PubMed

Small, Kade; Kopf, R Keller; Watts, Robyn J; Howitt, Julia

2014-01-01

Hypoxia represents a growing threat to biodiversity in freshwater ecosystems. Here, aquatic surface respiration (ASR) and oxygen thresholds required for survival in freshwater and simulated blackwater are evaluated for four lowland river fishes native to the Murray-Darling Basin (MDB), Australia. Juvenile stages of predatory species including golden perch Macquaria ambigua, silver perch Bidyanus bidyanus, Murray cod Maccullochella peelii, and eel-tailed catfish Tandanus tandanus were exposed to experimental conditions of nitrogen-induced hypoxia in freshwater and hypoxic blackwater simulations using dried river red gum Eucalyptus camaldulensis leaf litter. Australia's largest freshwater fish, M. peelii, was the most sensitive to hypoxia but given that we evaluated tolerances of juveniles (0.99 ± 0.04 g; mean mass ±SE), the low tolerance of this species could not be attributed to its large maximum attainable body mass (>100,000 g). Concentrations of dissolved oxygen causing 50% mortality (LC50) in freshwater ranged from 0.25 ± 0.06 mg l(-1) in T. tandanus to 1.58 ± 0.01 mg l(-1) in M. peelii over 48 h at 25-26 °C. Logistic models predicted that first mortalities may start at oxygen concentrations ranging from 2.4 mg l(-1) to 3.1 mg l(-1) in T. tandanus and M. peelii respectively within blackwater simulations. Aquatic surface respiration preceded mortality and this behaviour is documented here for the first time in juveniles of all four species. Despite the natural occurrence of hypoxia and blackwater events in lowland rivers of the MDB, juvenile stages of these large-bodied predators are vulnerable to mortality induced by low oxygen concentration and water chemistry changes associated with the decomposition of organic material. Given the extent of natural flow regime alteration and climate change predictions of rising temperatures and more severe drought and flooding, acute episodes of hypoxia may represent an underappreciated risk to riverine fish communities.

Flow characteristics control turnover of polar trace organic compounds in the hyporheic zone of an urban lowland river

NASA Astrophysics Data System (ADS)

Schaper, Jonas L.; Seher, Wiebke; Jaeger, Anna; Galloway, Jason; Nuetzmann, Gunnar; Putschew, Anke; Lewandowski, Joerg

2017-04-01

Hyporheic zones are hypothesized to be important sinks for polar trace organic compounds (TrOCs) in lotic systems, mitigating potential adverse effects of TrOCs on ecosystem functioning and drinking water production. Predicting the fate of TrOCs in the hyporheic zone, however, is difficult as the attenuation rate itself as well as the biogeochemical factors and hydrological conditions controlling attenuation rates are unknown. We used time series of temperature depth profiles as well as heat pulse sensing with a 1D advection dispersion transport model to calculate first order attenuation rates of several TrOCs from equilibrium depth profiles in an urban lowland river in Berlin, Germany. Ring enclosures were used to prohibit horizontal flow and to create distinct biogeochemical conditions within the hyporheic zone. Flow characteristics as well as biogeochemical conditions showed pronounced differences between depth profiles inside and outside of enclosures. TrOCs attenuation rates varied considerably among compounds reflecting their general susceptibility to biodegradation and sorption. While for some compounds such as benzotriazole and sulfamethoxazole redox conditions had an influence on attenuation rates, the fate of other compounds was not affected by biogeochemical parameters. Under loosing conditions, hyporheic zones of urban lowland rivers can thus be regarded as sinks for TrOCs. Their effectiveness is dependent on both, hyporheic exchange characteristics as well as biogeochemical parameters.

Macrophytes: ecosystem engineers in UK urban rivers

NASA Astrophysics Data System (ADS)

Gibbs, H.; Gurnell, A.; Heppell, K.; Spencer, K.

2012-04-01

Macrophytes act as ecosystem engineers within river channels in that they have the ability to cause geomorphological and ecological change. They induce reductions in flow velocity and associated sediment accumulation, and their system of underground roots and rhizomes also reinforces the accumulated sediment reducing sediment erosion and resuspension and creating habitats. As sediments, particularly finer-grained, store contaminants including metals, this engineering means that in the specific context of urban rivers where sediments are more likely to be contaminated, macrophytes trap and hold contaminated sediments creating a potentially important sink of metals. However, depending on the ability for the macrophyte to reinforce the sediment and reduce erosion and resuspension, there is the potential for the sink to turn in to a source and metals to be released in to the overlying water. This research therefore looks at the ecosystem engineering ability of common macrophytes in UK urban rivers by looking at: (i) the effect upon flow velocity and sediment accumulation of Sparganium erectum (branched bur-reed); (ii) the sediment reinforcement ability of both S. erectum, Typha latifolia (bulrush) and Phalaris arundinacea (reed canary grass); and, (iii) the storage of metals within the sediment, overlying water and the macrophytes. Research was undertaken on the River Blackwater, an urban river in Surrey, UK which has extensive macrophyte growth. Flow velocity measurements and fine sediment depths were recorded both within and outside of dense stands of S. erectum. The uprooting resistance (as an indicator of sediment reinforcement) was measured for three species: S. erectum, T. latifolia and P. arundinacea. Additionally, some preliminary sampling was undertaken of the sediment, overlying water and the macrophytes to determine metal storage. Lower flow velocities and greater volumes of fine sediment were recorded within the stands of S. erectum as opposed to the

Assessing the drivers of dissolved organic matter export from two contrasting lowland catchments, U.K.

PubMed

Yates, Christopher A; Johnes, Penny J; Spencer, Robert G M

2016-11-01

Two lowland catchments in the U.K. were sampled throughout 2010-11 to investigate the dominant controls on dissolved organic matter quantity and composition. The catchments had marked differences in terms of nutrient status, land cover and contrasting lithologies resulting in differences in the dominant flow pathways (groundwater vs. surface water dominated). The Upper Wylye is a chalk stream with a baseflow index of 0.98, draining a catchment dominated by intensive agricultural production. Millersford Brook is a lowland peat catchment with a baseflow index of 0.43, draining a semi-natural catchment with heather moorland and coniferous forest. Samples were collected weekly between October 2010 and September 2011 from eleven sampling locations. Samples were analysed to determine dissolved organic carbon, nitrogen and phosphorus fractions with DOM composition evaluated via the DOC:DON ratio, DOC:DOP ratio, specific UV absorption at 254nm, absorbance ratio (a250:a365) and the spectral slope parameter between 350 and 400nm (S350-400). Significant differences were observed in all determinands between the catchments, over time, and spatially along nutrient enrichment and geoclimatic gradients. Seasonal variation in preferential flow pathways mobilising groundwater-derived DOM were identified as likely controls on the delivery of DOM in the permeable chalk dominated catchment. Steeper S350-400 values and elevated a250:a365 ratios in this catchment suggest material of a lower bulk aromatic C content and molecular weight delivered during the winter months when compared to the summer. DOC:DON ratios were markedly lower in the chalk catchment than the peatland catchment, reflecting the paucity of organic matter within the mineral soils of the chalk landscape, and higher fertiliser application rates. This manuscript highlights that DOM composition varies according to catchment landscape character and hydrological function. Copyright © 2016 The Authors. Published by Elsevier B

Erosion rates and landscape evolution of the lowlands of the Upper Paraguay river basin (Brazil) from cosmogenic 10Be

NASA Astrophysics Data System (ADS)

Pupim, Fabiano do Nascimento; Bierman, Paul R.; Assine, Mario Luis; Rood, Dylan H.; Silva, Aguinaldo; Merino, Eder Renato

2015-04-01

The importance of Earth's low sloping areas in regard to global erosion and sediment fluxes has been widely and vigorously debated. It is a crucial area of research to elucidate geologically meaningful rates of land-surface change and thus the speed of element cycling on Earth. However, there are large portions of Earth where erosion rates have not been well or extensively measured, for example, the tropical lowlands. The Cuiabana lowlands are an extensive low-altitude and low-relief dissected metamorphic terrain situated in the Upper Paraguay river basin, central-west Brazil. Besides exposures of highly variable dissected metamorphic rocks, flat residual lateritic caps related to a Late Cenozoic planation surface dominate interfluves of the Cuiabana lowlands. The timescale over which the lowlands evolved and the planation surface developed, and the rate at which they have been modified by erosion, are poorly known. Here, we present measurements of in situ produced cosmogenic 10Be in outcropping metamorphic bedrock and clastic-lateritic caps to quantify rates of erosion of the surface and associated landforms in order to better understand the Quaternary landscape evolution of these lowlands. Overall, slow erosion rates (mean 10 m/Ma) suggest a stable tectonic environment in these lowlands. Erosion rates vary widely between different lithologies (range 0.57 to 28.3 m/Ma) consistent with differential erosion driving regional landform evolution. The lowest erosion rates are associated with the low-relief area (irregular plains), where clastic-laterite (mean 0.67 m/Ma) and quartzite (mean 2.6 m/Ma) crop out, whereas the highest erosion rates are associated with dissection of residual hills, dominated by metasandstone (mean 11.6 m/Ma) and phyllite (mean 27.6 m/Ma). These data imply that the Cuiabana lowland is comprised of two dominant landform sets with distinct and different dynamics. Because the planation surface (mostly lowlands) is lowering and losing mass more

Bream (Abramis brama (L.)) as zoogeomorphic agents and ecosystem engineers: Implications for fine sediment transport in lowland rivers

NASA Astrophysics Data System (ADS)

Smith, James; Rice, Stephen; Hodgkins, Richard

2017-04-01

bream and the observation that shoals of bream commonly exceed one thousand individuals, it is plausible that bream are an important biological constituent of the fine sediment cascade within riverine systems. Complementary field work is underway to quantify the frequency-magnitude characteristics of the fine sediment plumes that feeding shoals of bream generate in lowland UK rivers.

Characterising DOC, DON and DOP flux in two contrasting lowland UK catchments: impacts of contrasting source character and connectivity on reach scale DOM signature

NASA Astrophysics Data System (ADS)

Yates, C. A.; Johnes, P.; Spencer, R. G.

2012-12-01

Riverine DOM is a significant component of C, N and P transport from source to sea. Research to date has focused on characterising DOC in upland and boreal moorland and forested catchments. Here we present the results of an investigation of DOM character and DOC, DON and DOP flux relative to C, N and P flux in two contrasting lowland UK catchments: the Wylye and Millersford Brook. Both were sampled at daily frequency at 3 sites over a 2 year period, (2010-11 WY, 2011-12 WY) with fluorescence EEMs and UV-Vis determined weekly. The Wylye is a Chalk catchment, underlain by a major aquifer. It has predominantly calcareous brown earth soils, intensive arable agriculture, scattered farms and riparian villages with a major settlement in the lower reaches of the river. There are few natural organic sources in the catchment and flows are baseflow dominated with a BFI of 0.93. DOC (NPOC) concentrations averaged 2.59 mg C/l in water year 2011-12, while Total N concentrations averaged 10.0 mg N/l, with DON averaging 0.9 mg N/l, and Total P concentrations averaged 0.18 mg/l with DOP averaging 0.026 mg/l. Millersford Brook drains peaty soils over glacial sands and clays, with moorland and forestry as the dominant land uses. Flows are dominated by overland and subsurface quick flow through with a BFI of 0.34. There is some low intensity grazing, no fertiliser use and no dwellings in the headwaters of the catchment. As a result nutrient concentrations are lower, but C flux is higher, with mean annual concentrations in WY 2011-12 of 0.93 mg TN/l, 0.051 mg TP/l, 8.83 mg DOC/l, 0.55 mg DON/l and 0.029 mg DOP/l. DOM character in Millersford Brook is comparable for that observed in other catchments with peaty soils and low acid neutralising capacity. The character of DOM varies along the length of the river, with HMW compounds dominating the signal in the headwaters, and LMW fluorescence intensities added to the signal in the lower reaches of the river, where septic tank effluent

River restoration: separating myths from reality

NASA Astrophysics Data System (ADS)

Friberg, N.; Woodward, G.

2015-12-01

River restorations are a social construct where degraded systems are physically modified to obtain a pre-disturbance set of attributes. These can be purely esthetic but are often linked to some kind of biotic recovery or the provision of important ecosystem services such as flood control or self-purification. The social setting of restoration projects, with a range of potential conflicts, significantly reduces scale of most interventions to a size with little room, or wish, for natural processes. We show that projects sizes are still very small and that the restoration target is not to recover natural geomorphic processes but rather to fulfil human perception of what a nice stream looks like. One case from Danish lowland streams, using a space-for-time substitution approach, shows excess use of pebble and gravel when restoring channelized sandy bottom streams, de-coupling the link between energy and substrate characteristics that are found in natural lowland systems. This has implication for both the biological structure and functioning of these systems as a direct link between substrate heterogeneity and macroinvertebrate diversity was not found in restored streams, while the density of grazer increased indicating an increased use of periphyton as a basal resource. Another case of adding woody debris to UK lowland streams, using a BACI study design, showed very little effect on the macroinvertebrate community even after a 100-year flood, which indicate that added tree trunks did not provide additional flow refugia. We suggest that restoration schemes should aim at restoring the natural physical structural complexity in the streams and at the same time enhance the possibility of re-generating the natural geomorphological processes sustaining the habitats in streams and rivers.

Estimating River Bathymetry, Roughness, and Discharge from Remote Sensing Measurements of River Height on the River Severn, U.K.

NASA Astrophysics Data System (ADS)

Durand, Michael; Neal, Jeff; Rodriguez, Ernesto

2013-09-01

The Surface Water and Ocean Topography (SWOT) satellite is a swath-mapping radar interferometer that will provide water elevations over inland water bodies and over the ocean. Here we present a Bayesian algorithm that calculates a best estimate of river bathymetry, roughness coefficient, and discharge based on measurements of river height and slope. On the River Severn, UK, we use gage estimates of height and slope during an in-bank flow event to illustrate algorithm functionality. We validate our estimates of river bathymetry and discharge using in situ measurements. We first assumed that the lateral inflows from smaller tributaries were known. In this case, an accurate inverse to bathymetry and roughness was obtained giving a discharge RMSE of 10 %. We then allowed the lateral inflows to be unknown; accuracy in the bathymetry estimates dropped in this case, giving a discharge RMSE of 36 %. Finally, we explored the case where bathymetry in one reach was known; in this case, discharge RMSE was 15.6 %.

The Lowland Rivers of The Netherlands - Geodiversity and Cultural Heritage on 19th and early 20th century Landscape Paintings

NASA Astrophysics Data System (ADS)

Jungerius, Pieter Dirk; van den Ancker, Hanneke; Moes, Constance

2015-04-01

One of the major Dutch landscapes is formed by lowland rivers. They divide the country in a southern and a northern part, both physically and culturally. We screened the freely available database of 19th and early 20th century paintings of Simonis & Buunk, www.simonis-buunk.com, looking for lowland river landscapes depicting geodiversity and cultural heritage relationships (See References for other landscapes). Emperor Napoleon declared The Netherlands as naturally belonging to his empire as its lands originated from muds originating in France and transported there by the big rivers. A description that may have given rise to the idea of the Netherlands as a delta, but from a geomorphological perspective The Netherlands consists of series of river plains of terrestrial origin, of which the north-western part are subsiding and invaded by the sea. Now, the rivers Meuse and Rhine (including its branches Waal and IJssel) meander through ever larger river plains before reaching the North Sea. They end in estuaries, something one would not expect of rivers with catchments discharging a large part of Western Europe. Apart from the geological subsidence, the estuaries might be due to human interference, the exploitation of peat and building of dikes since the 11th century, heavy storms and the strong tidal currents. Archaeological finds show Vikings and Romans already used the river Rhine system for trading and transporting goods. During the Roman Empire the Rhine was part of The Limes, the northern defence line of the empire. Romans already influenced the distribution of water over the different river branches. Since the middle of the 19th century groins and canalization drastically changed the character of the rivers. The 19th and early 20th century landscape paintings illustrate this change as well as changes in land use. Examples of geodiversity and cultural heritage relationships shown: - meanders and irregular banks disappear as river management increases, i.a. bends

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.

Analysis of land use and climate change impacts by comparing river flow records for headwaters and lowland reaches

NASA Astrophysics Data System (ADS)

Fazel, Nasim; Torabi Haghighi, Ali; Kløve, Bjørn

2017-11-01

The natural flow regime of rivers has been strongly altered world-wide, resulting in ecosystem degradation and lakes drying up, especially in arid and semi-arid regions. Determining whether this is due mainly to climate change or to water withdrawal for direct human use (e.g. irrigation) is difficult, particularly for saline lake basins where hydrology data are scarce. In this study, we developed an approach for assessing climate and land use change impacts based on river flow records for headwater and lowland reaches of rivers, using the case of Lake Urmia basin, in north-westen Iran. Flow regimes at upstream and downstream stations were studied before and after major dam construction and irrigation projects. Data from 57 stations were used to establish five different time intervals representing 10 different land use development periods (scenarios) for upstream (not impacted) and downstream (impacted) systems. An existing river impact (RI) index was used to assess changes in three main characteristics of flow (magnitude, timing and, intra-annual variability). The results showed that irrigation was by far the main driving force for river flow regime changes in the lake basin. All stations close to the lake and on adjacent plains showed significantly higher impacts of land use change than headwaters. As headwaters are relatively unaffected by agriculture, the non-significant changes observed in headwater flow regimes indicate a minor effect of climate change on river flows in the region. The benefit of the method developed is clear interpretation of results based on river flow records, which is useful in communicating land use and climate change information to decision makers and lake restoration planners.

A national-scale analysis of the impacts of drought on water quality in UK rivers

NASA Astrophysics Data System (ADS)

Coxon, G.; Howden, N. J. K.; Freer, J. E.; Whitehead, P. G.; Bussi, G.

2015-12-01

Impacts of droughts on water quality qre difficult to quanitify but are essential to manage ecosystems and maintain public water supply. During drought, river water quality is significantly changed by increased residence times, reduced dilution and enhanced biogeochemical processes. But, the impact severity varies between catchments and depends on multiple factors including the sensitivity of the river to drought conditions, anthropogenic influences in the catchment and different delivery patterns of key nutrient, contaminant and mineral sources. A key constraint is data availability for key water quality parameters such that impacts of drought periods on certain determinands can be identified. We use national-scale water quality monitoring data to investigate the impacts of drought periods on water quality in the United Kingdom (UK). The UK Water Quality Sampling Harmonised Monitoring Scheme (HMS) dataset consists of >200 UK sites with weekly to monthly sampling of many water quality variables over the past 40 years. This covers several major UK droughts in 1975-1976, 1983-1984,1989-1992, 1995 and 2003, which cover severity, spatial and temporal extent, and how this affects the temporal impact of the drought on water quality. Several key water quality parameters, including water temperature, nitrate, dissolved organic carbon, orthophosphate, chlorophyll and pesticides, are selected from the database. These were chosen based on their availability for many of the sites, high sampling resolution and importance to the drinking water function and ecological status of the river. The water quality time series were then analysed to investigate whether water quality during droughts deviated significantly from non-drought periods and examined how the results varied spatially, for different drought periods and for different water quality parameters. Our results show that there is no simple conclusion as to the effects of drought on water quality in UK rivers; impacts are

The influence of water depth and flow regime on phytoplankton biomass and community structure in a shallow, lowland river

USGS Publications Warehouse

Leland, H.V.

2003-01-01

The taxonomic composition and biomass of phytoplankton in the San Joaquin River, California, were examined in relation to water depth, flow regime, and water chemistry. Without substantial tributary inflow, maintenance demands exceeded algal production during summer and autumn in this eutrophic, 'lowland type' river due to light-limiting conditions for algal growth. Streamflow from tributaries that drain the Sierra Nevada contributed to a substantial net gain in algal production during the spring and summer by increasing water transparency and the extent of turbulence. Abundances of the major taxa (centric diatoms, pennate diatoms and chlorophytes) indicated differing responses to the longitudinal variation in water depth and flow regime, with the areal extent of pools and other geomorphic features that influence time-for-development being a major contributing factor to the selection of species. Tychoplanktonic species were most abundant upstream and in tributaries that drain the San Joaquin Valley. Seasonally-varying factors such as water temperature that influence algal growth rates also contributed significantly to the selection of species. Nutrient limitation appears not to be a primary constraint on species selection in the phytoplankton of this river.

An assessment of the impact of upland afforestation on lowland river reaches: the Afon Trannon, mid-Wales

NASA Astrophysics Data System (ADS)

Mount, N. J.; Sambrook Smith, G. H.; Stott, T. A.

2005-01-01

Upland afforestation in the UK was the largest rural land-use change last century. As a consequence, the bed load yields of upland catchments increased substantially. Circumstantial evidence suggests that, when this increased load reaches the lowland catchment, it is deposited, triggering flow diversion and channel instability. However, despite the widespread adoption of this theory, it remains to be properly tested. This paper uses aerial photograph analysis and contemporary channel digital terrain models (DTMs) to assess this concept on the Afon Trannon, mid-Wales, the upper catchment of which was afforested between 1948 and 1978. Construction of a sediment budget demonstrates that upland catchment bed load yields are only equivalent to localized inputs of gravel from bank erosion and are therefore unlikely to be totally responsible for producing the high rates of channel change observed in some lowland reaches. Channel instability appears to be more related to the nature of the local bank input as those reaches where gravel is not present in the bank material are stable. Additionally, flood magnitude and frequency are shown to have increased since 1988, a factor of at least equal importance to that of bed load yields from either upland catchments or local bank erosion. It is concluded that, in contrast to previous work, afforestation in the uplands has only a minor influence on downstream reaches of the Afon Trannon. Situations where upland afforestation may have a greater impact on downstream reaches are discussed and the implications for best management practice explored.

Phosphorus load to surface water from bank erosion in a Danish lowland river basin.

PubMed

Kronvang, Brian; Audet, Joachim; Baattrup-Pedersen, Annette; Jensen, Henning S; Larsen, Søren E

2012-01-01

Phosphorus loss from bank erosion was studied in the catchment of River Odense, a lowland Danish river basin, with the aim of testing the hypothesis of whether stream banks act as major diffuse phosphorus (P) sources at catchment scale. Furthermore, the study aimed at analyzing the impact of different factors influencing bank erosion and P loss such as stream order, anthropogenic disturbances, width of uncultivated buffer strips, and the vegetation of buffer strips. A random stratified procedure in geographical information system (GIS) was used to select two replicate stream reaches covering different stream orders, channelized vs. naturally meandering channels, width of uncultivated buffer strips (≤ 2 m and ≥ 10 m), and buffer strips with different vegetation types. Thirty-six 100-m stream reaches with 180 bank plots and a total of 3000 erosion pins were established in autumn 2006, and readings were conducted during a 3-yr period (2006-2009). The results show that neither stream size nor stream disturbance measured as channelization of channel or the width of uncultivated buffer strip had any significant ( < 0.05) influence on bank erosion and P losses during each of the 3 yr studied. In buffer strips with natural trees bank erosion was significantly ( < 0.05) lower than in buffer strips dominated by grass and herbs. Gross and net P input from bank erosion amounted to 13.8 to 16.5 and 2.4 to 6.3 t P, respectively, in the River Odense catchment during the three study years. The net P input from bank erosion equaled 17 to 29% of the annual total P export and 21 to 62% of the annual export of P from diffuse sources from the River Odense catchment. Most of the exported total P was found to be bioavailable (71.7%) based on a P speciation of monthly suspended sediment samples collected at the outlet of the river basin. The results found in this study have a great importance for managers working with P mitigation and modeling at catchment scale. Copyright © by the

Water quality of the Luján river, a lowland watercourse near the metropolitan area of Buenos Aires (Argentina).

PubMed

Castañé, Patricia M; Sánchez-Caro, Aníbal; Salibián, Alfredo

2015-10-01

Luján river is a lowland watercourse which runs 130 km before flowing into the Río de la Plata Estuary, and receives a mixture of domestic and industrial wastewaters originating at its margins. In order to know the physicochemical profile of its surface water, 36 physical-chemical variables were analyzed in samples collected seasonally between 2004 and 2006 at three sampling stations. The results obtained through the principal component analysis (PCA) suggest that the variations in water quality are explained by natural components (soluble salts; metals), nonpoint inputs (nutrients), and anthropogenic (organic and bacterial) and industrial (toxic heavy metals) pollutants. The cases did not fit a clear spatial or seasonal pattern when plotted against the first two PCA axes. The three water quality indices calculated gave middle scores; Sampling station 1 gave a baseline for the comparison of the river's water quality along its course while Sampling station 3 (downriver) was the most degraded. A variety of pollution pulses reach and affect the watercourse downstream. Cities' sewage discharges into the river seem to be the major polluting factor, together with natural metals and other solutes loads that are present from the headwaters. The results may be useful for the development of local and regional mitigation and remediation programs regarding toxic and eutrophying loads in the upper basin of the river.

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.

Evaluating the effect of nutrient redistribution by animals on the phosphorus cycle of lowland Amazonia

NASA Astrophysics Data System (ADS)

Buendía, Corina; Kleidon, Axel; Manzoni, Stefano; Reu, Björn; Porporato, Amilcare

2018-01-01

Phosphorus (P) availability decreases with soil age and potentially limits the productivity of ecosystems growing on old and weathered soils. Despite growing on ancient soils, ecosystems of lowland Amazonia are highly productive and are among the most biodiverse on Earth. P eroded and weathered in the Andes is transported by the rivers and deposited in floodplains of the lowland Amazon basin creating hotspots of P fertility. We hypothesize that animals feeding on vegetation and detritus in these hotspots may redistribute P to P-depleted areas, thus contributing to dissipate the P gradient across the landscape. Using a mathematical model, we show that animal-driven spatial redistribution of P from rivers to land and from seasonally flooded to terra firme (upland) ecosystems may sustain the P cycle of Amazonian lowlands. Our results show how P imported to land by terrestrial piscivores in combination with spatial redistribution of herbivores and detritivores can significantly enhance the P content in terra firme ecosystems, thereby highlighting the importance of food webs for the biogeochemical cycling of Amazonia.

Spatial Scaling of Environmental Variables Improves Species-Habitat Models of Fishes in a Small, Sand-Bed Lowland River

PubMed Central

Radinger, Johannes; Wolter, Christian; Kail, Jochem

2015-01-01

Habitat suitability and the distinct mobility of species depict fundamental keys for explaining and understanding the distribution of river fishes. In recent years, comprehensive data on river hydromorphology has been mapped at spatial scales down to 100 m, potentially serving high resolution species-habitat models, e.g., for fish. However, the relative importance of specific hydromorphological and in-stream habitat variables and their spatial scales of influence is poorly understood. Applying boosted regression trees, we developed species-habitat models for 13 fish species in a sand-bed lowland river based on river morphological and in-stream habitat data. First, we calculated mean values for the predictor variables in five distance classes (from the sampling site up to 4000 m up- and downstream) to identify the spatial scale that best predicts the presence of fish species. Second, we compared the suitability of measured variables and assessment scores related to natural reference conditions. Third, we identified variables which best explained the presence of fish species. The mean model quality (AUC = 0.78, area under the receiver operating characteristic curve) significantly increased when information on the habitat conditions up- and downstream of a sampling site (maximum AUC at 2500 m distance class, +0.049) and topological variables (e.g., stream order) were included (AUC = +0.014). Both measured and assessed variables were similarly well suited to predict species’ presence. Stream order variables and measured cross section features (e.g., width, depth, velocity) were best-suited predictors. In addition, measured channel-bed characteristics (e.g., substrate types) and assessed longitudinal channel features (e.g., naturalness of river planform) were also good predictors. These findings demonstrate (i) the applicability of high resolution river morphological and instream-habitat data (measured and assessed variables) to predict fish presence, (ii) the

New insights on historic droughts in the UK: Analysis of 200 river flow reconstructions for 1890-2015

NASA Astrophysics Data System (ADS)

Parry, Simon; Barker, Lucy; Hannaford, Jamie; Prudhomme, Christel; Smith, Katie; Svensson, Cecilia; Tanguy, Maliko

2017-04-01

Hydrological droughts of the last 50 years in the UK have been well characterised owing to a relatively dense hydrometric network. Prior to this, observed river flow data were generally limited in their spatial coverage and often subject to considerable uncertainty. Whilst qualitative records indicate the occurrence of severe droughts in the late 19th and early 20th centuries, including scenarios which may cause substantial impacts to contemporary water supply systems, existing observations are not sufficient to describe their spatio-temporal characteristics. As such, insights on drought in the UK are constrained and a range of stakeholders including water companies and regulators would benefit from a more thorough assessment of historic drought characteristics and their variability. The multi-disciplinary Historic Droughts project aims to rigorously characterise droughts in the UK to inform improved drought management and communication. Driven by rainfall and potential evapotranspiration data that have been extended using recovered records, lumped catchment hydrological models are used to reconstruct daily river flows from 1890 to 2015 for more than 200 catchments across the UK. The reconstructions are derived within a state-of-the-art modelling framework which allows a comprehensive assessment of model, structure and parameter uncertainty. Standardised and threshold-based indicators are applied to the river flow reconstructions to identify and characterise hydrological drought events. The reconstructions are most beneficial in comprehensively describing well known but poorly quantified late 19th and early 20th century droughts, placing the spatial and temporal footprint of these often extreme events within the context of modern episodes for the first time. Oscillations between drought-rich and drought-poor periods are shown not to be limited to the recent observational past, providing an increased sample size of events against which to test a range of airflow and

Nested monitoring approaches to delineate groundwater trichloroethene discharge to a UK lowland stream at multiple spatial scales.

PubMed

Weatherill, John; Krause, Stefan; Voyce, Kevin; Drijfhout, Falko; Levy, Amir; Cassidy, Nigel

2014-03-01

Integrated approaches for the identification of pollutant linkages between aquifers and streams are of crucial importance for evaluating the environmental risks posed by industrial contaminants like trichloroethene (TCE). This study presents a systematic, multi-scale approach to characterising groundwater TCE discharge to a 'gaining' UK lowland stream receiving baseflow from a major Permo-Triassic sandstone aquifer. Beginning with a limited number of initial monitoring points, we aim to provide a 'first pass' mechanistic understanding of the plume's fate at the aquifer/stream interface using a novel combination of streambed diffusion samplers, riparian monitoring wells and drive-point mini-piezometers in a spatially nested sampling configuration. Our results indicate the potential discharge zone of the plume to extend along a stream reach of 120 m in length, delineated by a network of 60 in-situ diffusion samplers. Within this section, a 40 m long sub-reach of higher concentration (>10 μg L(-1)) was identified; centred on a meander bend in the floodplain. 25 multi-level mini-piezometers installed to target this down-scaled reach revealed even higher TCE concentrations (20-40 μg L(-1)), significantly above alluvial groundwater samples (<6 μg L(-1)) from 15 riparian monitoring wells. Significant lateral and vertical spatial heterogeneity in TCE concentrations within the top 1m of the streambed was observed with the decimetre-scale vertical resolution provided by multi-level mini-piezometers. It appears that the distribution of fine-grained material in the Holocene deposits of the riparian floodplain and below the channel is exerting significant local-scale geological controls on the location and magnitude of the TCE discharge. Large-scale in-situ biodegradation of the plume was not evident during the monitoring campaigns. However, detections of cis-1,2-dichloroethene and vinyl chloride in discrete sections of the sediment profile indicate that shallow (e.g., <20

New insights into biogeochemical processing gained from sub-daily river monitoring

NASA Astrophysics Data System (ADS)

Halliday, S. J.; Wade, A. J.; Skeffington, R. A.; Bowes, M.; Palmer-Felgate, E.; Loewenthal, M.; Jarvie, H.; Neal, C.; Reynolds, B.; Gozzard, E.; Newman, J.

2012-12-01

This talk will focus on the insights obtained from sub-daily hydrochemical monitoring for a sustained time periods (> 1 year), at multiple sites within a catchment and across different catchment types. Sub-daily instream hydrochemical dynamics were investigated, using non-stationary time-series analysis techniques, for two catchments representative of upland and lowland UK. The River Hafren at Plynlimon, mid-Wales drains an upland catchment where half the land cover is unmanaged moorland and the other half is first generation plantation forestry. The Hafren was monitored at two sites on a 7-hourly basis, between March 2007 and January 2009, using a Xian automatic sampler. The River Enborne, Berkshire, southeast England, is a rural lowland catchment, impacted by agricultural runoff, and septic tank and sewage treatment works discharges. The Enborne was monitored on an hourly basis between November 2009 and February 2012, using in situ field deployable analytical equipment to measure: Total Reactive Phosphorus (TRP: Systea Micromac C), Nitrate (Hach-Lange Nitratax), pH, dissolved oxygen, conductivity and water temperature (YSI 6600 Multi-parameter sonde). The results reveal complex diurnal patterns which exhibit seasonal changes in phase and amplitude, and are influenced by both flow conditions and nutrient sources. The comparison of the upland and lowland nitrate time series highlights how the different nitrogen sources within each system results in marked differences in the seasonal and diurnal dynamics, with a seasonal maximum in winter and a single peak diurnal cycle in the upland system, compared to a summer maximum and a two peak diurnal cycle in the lowland system. The analysis of TRP and nitrate concentrations in the Enborne catchment, in combination with flow, pH, dissolved oxygen, conductivity and water temperature, allowed the main processes controlling the observed sub-daily nutrient dynamics to be investigated. The different monitoring approaches adopted

Spatial relations between floodplain environments and land use - land cover of a large lowland tropical river valley: Pánuco basin, México.

PubMed

Hudson, Paul F; Colditz, René R; Aguilar-Robledo, Miguel

2006-09-01

Large lowland river valleys include a variety of floodplain environments that represent opportunities and constraints for human activities. This study integrates extensive field observations and geomorphic data with analysis of satellite remote sensing data to examine spatial relations between land use/land cover (LULC) and floodplain environments in the lower Pánuco basin of eastern Mexico. The floodplain of the lower Pánuco basin was delineated by combining a digital elevation model with a satellite image of a large flood event. The LULC was classified by combining a hybrid classification strategy with image stratification, applied to 15-m-resolution ASTER data. A geomorphic classification of floodplain environments was performed using a dry-stage image (ASTER data) and a 1993 Landsat image acquired during a large flood event. Accuracy assessment was based on aerial photographs (1:38,000), global positioning satellite ground-truthing, and a Landsat 7ETM(+) image from 2000, which resulted in an overall accuracy of 82.9% and a KHAT of 79.8% for the LULC classification. The geomorphic classification yielded 83.5% overall accuracy, whereas the KHAT was 81.5%. LULC analysis was performed for the entire floodplain and individually within four valley segments. The analysis indicates that the study area is primarily utilized for grazing and farming. Agriculture is primarily associated with coarse-grained (sandy/silty) natural levee and point bar units close to the river channel, whereas cattle grazing occurs in distal and lower-lying reaches dominated by cohesive fine-grained (clayey) deposits, such as backswamps. In the Pánuco valley, wetlands and lakes occur within backswamp environments, whereas in the Moctezuma segments, wetlands and lakes are associated with relict channels. This study reveals considerable variation in LULC related to spatial differences in floodplain environments and illustrates the importance of considering older anthropogenic influences on the

Estimation of the Probable Maximum Flood for a Small Lowland River in Poland

NASA Astrophysics Data System (ADS)

Banasik, K.; Hejduk, L.

2009-04-01

The planning, designe and use of hydrotechnical structures often requires the assesment of maximu flood potentials. The most common term applied to this upper limit of flooding is the probable maximum flood (PMF). The PMP/UH (probable maximum precipitation/unit hydrograph) method has been used in the study to predict PMF from a small agricultural lowland river basin of Zagozdzonka (left tributary of Vistula river) in Poland. The river basin, located about 100 km south of Warsaw, with an area - upstream the gauge of Plachty - of 82 km2, has been investigated by Department of Water Engineering and Environmenal Restoration of Warsaw University of Life Sciences - SGGW since 1962. Over 40-year flow record was used in previous investigation for predicting T-year flood discharge (Banasik et al., 2003). The objective here was to estimate the PMF using the PMP/UH method and to compare the results with the 100-year flood. A new relation of depth-duration curve of PMP for the local climatic condition has been developed based on Polish maximum observed rainfall data (Ozga-Zielinska & Ozga-Zielinski, 2003). Exponential formula, with the value of exponent of 0.47, i.e. close to the exponent in formula for world PMP and also in the formula of PMP for Great Britain (Wilson, 1993), gives the rainfall depth about 40% lower than the Wilson's one. The effective rainfall (runoff volume) has been estimated from the PMP of various duration using the CN-method (USDA-SCS, 1986). The CN value as well as parameters of the IUH model (Nash, 1957) have been established from the 27 rainfall-runoff events, recorded in the river basin in the period 1980-2004. Varibility of the parameter values with the size of the events will be discussed in the paper. The results of the analyse have shown that the peak discharge of the PMF is 4.5 times larger then 100-year flood, and volume ratio of the respective direct hydrographs caused by rainfall events of critical duration is 4.0. References 1.Banasik K

Estimation of the Probable Maximum Flood for a Small Lowland River in Poland

NASA Astrophysics Data System (ADS)

Banasik, K.; Hejduk, L.

2009-04-01

The planning, designe and use of hydrotechnical structures often requires the assesment of maximu flood potentials. The most common term applied to this upper limit of flooding is the probable maximum flood (PMF). The PMP/UH (probable maximum precipitation/unit hydrograph) method has been used in the study to predict PMF from a small agricultural lowland river basin of Zagozdzonka (left tributary of Vistula river) in Poland. The river basin, located about 100 km south of Warsaw, with an area - upstream the gauge of Plachty - of 82 km2, has been investigated by Department of Water Engineering and Environmenal Restoration of Warsaw University of Life Sciences - SGGW since 1962. Over 40-year flow record was used in previous investigation for predicting T-year flood discharge (Banasik et al., 2003). The objective here was to estimate the PMF using the PMP/UH method and to compare the results with the 100-year flood. A new relation of depth-duration curve of PMP for the local climatic condition has been developed based on Polish maximum observed rainfall data (Ozga-Zielinska & Ozga-Zielinski, 2003). Exponential formula, with the value of exponent of 0.47, i.e. close to the exponent in formula for world PMP and also in the formula of PMP for Great Britain (Wilson, 1993), gives the rainfall depth about 40% lower than the Wilson's one. The effective rainfall (runoff volume) has been estimated from the PMP of various duration using the CN-method (USDA-SCS, 1986). The CN value as well as parameters of the IUH model (Nash, 1957) have been established from the 27 rainfall-runoff events, recorded in the river basin in the period 1980-2004. Varibility of the parameter values with the size of the events will be discussed in the paper. The results of the analyse have shown that the peak discharge of the PMF is 4.5 times larger then 100-year flood, and volume ratio of the respective direct hydrographs caused by rainfall events of critical duration is 4.0. References 1.Banasik K

Regulation and seasonal dynamics of extracellular enzyme activities in the sediments of a large lowland river.

PubMed

Wilczek, Sabine; Fischer, Helmut; Pusch, Martin T

2005-08-01

We tested whether seasonal changes in the sources of organic substances for microbial metabolism were reflected changes in the activities of five extracellular enzymes in the eighth order lowland River Elbe, Germany. Leucine aminopeptidase showed the highest activities in the water column and the sediments, followed by phosphatase > beta-glucosidase > alpha-glucosidase > exo-1,4-beta-glucanase. Individual enzymes exhibited characteristic seasonal dynamics, as indicated by their relative contribution to cumulative enzyme activity. Leucine aminopeptidase was significantly more active in spring and summer. In contrast, the carbohydrate-degrading enzymes peaked in autumn, and beta-glucosidase activity peaked once again in winter. Thus, in sediments, the ratio of leucine aminopeptidase/beta-glucosidase reached significant higher medians in spring and summer (5-cm depth: ratio 7.7; 20-cm depth: ratio 10.1) than in autumn and winter (5-cm depth: ratio 3.7, 20-cm depth: ratio 6.3). The relative activity of phosphatase in the sediments was seasonally related to both the biomass of planktonic algae as well as to the high content of total particulate phosphorus in autumn and winter. Due to temporal shifts in organic matter supply and changes in the storage capacity of sediments, the seasonal peaks of enzyme activities in sediments exhibited a time lag of 2-3 months compared to that in the water column, along with a significant extension of peak width. Hence, our data show that the seasonal pattern of extracellular enzyme activities provides a sensitive approach to infer seasonal or temporary availability of organic matter in rivers from autochthonous and allochthonous sources. From the dynamics of individual enzyme activities, a consistent synoptic pattern of heterotrophic functioning in the studied river ecosystem could be derived. Our data support the revised riverine productivity model predicting that the metabolism of organic matter in high-order rivers is mainly fuelled

Permafrost and lakes control river isotope composition across a boreal Arctic transect in the Western Siberian lowlands

NASA Astrophysics Data System (ADS)

Ala-aho, P.; Soulsby, C.; Pokrovsky, O. S.; Kirpotin, S. N.; Karlsson, J.; Serikova, S.; Manasypov, R.; Lim, A.; Krickov, I.; Kolesnichenko, L. G.; Laudon, H.; Tetzlaff, D.

2018-03-01

The Western Siberian Lowlands (WSL) store large quantities of organic carbon that will be exposed and mobilized by the thawing of permafrost. The fate of mobilized carbon, however, is not well understood, partly because of inadequate knowledge of hydrological controls in the region which has a vast low-relief surface area, extensive lake and wetland coverage and gradually increasing permafrost influence. We used stable water isotopes to improve our understanding of dominant landscape controls on the hydrology of the WSL. We sampled rivers along a 1700 km South-North transect from permafrost-free to continuous permafrost repeatedly over three years, and derived isotope proxies for catchment hydrological responsiveness and connectivity. We found correlations between the isotope proxies and catchment characteristics, suggesting that lakes and wetlands are intimately connected to rivers, and that permafrost increases the responsiveness of the catchment to rainfall and snowmelt events, reducing catchment mean transit times. Our work provides rare isotope-based field evidence that permafrost and lakes/wetlands influence hydrological pathways across a wide range of spatial scales (10-105 km2) and permafrost coverage (0%-70%). This has important implications, because both permafrost extent and lake/wetland coverage are affected by permafrost thaw in the changing climate. Changes in these hydrological landscape controls are likely to alter carbon export and emission via inland waters, which may be of global significance.

Monitoring runoff and nutrient transport in the coastal zone of a Danish lowland river

NASA Astrophysics Data System (ADS)

Ovesen, N. B.; Windolf, J.; Kronvang, B.

2012-04-01

Denmark has a very long coastline compared to its total area, and therefore large parts of the lower river reaches are influenced by tidal and coastal backwater effects. In general the gradients of these lowland rivers are very low, and furthermore thousands of small watercourses are flowing directly to the sea along the coastline. This situation makes it impossible to gauge the runoff to many fjords and marine inland waters utilizing traditional monitoring techniques, and consequently, even though Denmark is covered with several hundreds of gauging stations, only 50 percent of the country is gauged. Models are today used to estimate the total runoff and loads of nutrients to coastal waters. One of the major problems in the calibration of the models is however, the lacking of data from the lower part of rivers influenced by tidal and coastal backwater. In order to investigate the possibilities of improving the Danish gauging network and to test the models used for runoff estimation in the ungauged areas, a new monitoring station was established in the summer of 2011 in the River Skjern very close to the outlet in Ringkobing Fjord at the west coast of Jutland. The hydraulic conditions are here affected by tidal and backwater effects and the nutrient transport may be influenced by stratified flow conditions. The catchment area to the new station is 2455 km2, and the width of the channel is 70-80meters. The velocity distribution is measured in the profile by both horizontal and vertical multi cell Doppler sensors. Conductivity (salinity), turbidity and water temperature are measured by sensors in 2 levels, near bottom and in the upper part of the depth profile. Time integrated water samples are collected also in 2 levels with a 2 hour interval and analyzed for total nitrogen, nitrate, ammonium, total phosphorous, and phosphate. The wind speed and direction is registered at the station. The preliminary results show a strong correlation between the water velocities and

Inventory and Comparison of Floodplain Embankment along Large Rivers

NASA Astrophysics Data System (ADS)

Hudson, Paul

2016-04-01

Flood control is a fundamental human response to flood risk, and floodplain embankment by dike (levee) construction is among the oldest forms of societal impacts to natural systems. Large lowland alluvial valleys are some of Earth's most distinctive environments and represent high levels of geodiversity and biodiversity. Embankment of large lowland alluvial river valleys alters fundamental processes related to floodplain hydrology, sedimentation, and ecology and eventually results in a transformation of the embanked floodplain environment. Since embankment, many large lowland floodplains have been heaviliy modified for floodplain agriculture and include high population densities, increasing flood risk. While there is much discussion about the pros and cons of dike construction and the impact to floodplain environments there is no systematic inventory which documents the magnitude and intensity of floodplain embankment to lowland rivers. In this study we characterize and inventory floodplain embankment along large lowland alluvial valleys. The review includes some of Earth's largest embanked fluvial systems, and primarilly focuses on northern hemisphere rivers in the United States, Europe and Asia. Data sources includes the U.S. National Levee Database, SRTM DEM, recently obtained high resolution satellite imagery, various national topographic map series, and hydrologic data from the published literature. These data are integrated into a GIS framework to facilitate the measurement and characterisation of floodplain embankment. Spatial indices of floodplain embankment are constructed, including the intensity of embankment and how it relates to the natural floodplain and constriction of flooding.

Connectivity from source to sink in a lowland area: the Loire river basin (France)

NASA Astrophysics Data System (ADS)

Gay, Aurore; Cerdan, Olivier; Degan, Francesca; Salvador, Sebastien

2014-05-01

Sediment connectivity relates to the transfer of sediments from sources to sinks via runoff and in channel transport. It is highly dependent on spatial variability of landscape properties such as differences in morphology, land use and infiltration/runoff characteristics but may also vary in time due to differences in rainfall amount/intensity and changes in vegetation cover throughout the year. In the Loire river basin, we found that sediment fluxes displayed strong variations in space but also at the interannual and seasonnal time scales (Gay et al. 2013). In this context, our goal is to better understand and quantify hillslope sediment redistributions within this lowland area thanks to the use of semi distributed connectivity approach. To this aim, Borselli's index of connectivity (IC, Borselli et al., 2008) is selected to assess hillslope connectivity at annual and seasonal time scales. Several improvements are proposed to take into account the coupling of the structural landscape connectivity and its hydrosedimentary response. Parameters such as rainfall intensity and differences in seasonal land cover are integrated into the model to account for landscape variations through time. Infiltration and runoff indices were also tested. Preliminary results confirm the variability of landscape connectivity throughout the year. The integration of the index of infiltration and runoff properties of landscape (IDPR) as defined by Mardhel et al. 2004 seems to improve the IC model outputs. From this first step, in-stream sediment connectivity index should be developed for a better understanding and assessment of sediment redistributions at the entire catchment scale. L. Borselli L., Cassi P., Torri D. Prolegomena to sediment and flow connectivity in the landscape: a GIS and field numerical assessment. Catena, 75 (2008), pp. 268-277 Gay A., Cerdan O., Delmas M., Desmet M., Variability of sediment yields in the Loire river basin (France): the role of small scale catchments

Morphological Assessment of Reconstructed Lowland Streams in the Netherlands

NASA Astrophysics Data System (ADS)

Hoitink, T.; Eekhout, J.; de Brouwer, J.; Verdonschot, P.

2014-12-01

Channelisation measures taken halfway the 20th century have had destructive consequences for the diversity of the ecology in the majority of the lowland streams in countries such as the Netherlands. Re-meandering is the common practice in restoring these lowland streams. Three lowland streams were monitored during the initial two years after construction of a new channel. The monitoring program included morphological surveys, sediment sampling, habitat pattern surveys, and discharge and water level measurements. Adjustments of the longitudinal bed profile formed the main morphological response. These adjustments were most likely caused by a lack of longitudinal connectivity of the streams as a whole, interrupting transport of sediment at locations of weirs and culverts. Bank erosion was observed only in a limited number of channel bends, and was often related to floodplain heterogeneity. Longitudinal channel bed adjustments and bank erosion were mainly caused by exogenous influences. In channel bends, the cross-sectional shape transformed from trapezoidal to the typical asymmetrical shape as found in meandering rivers. This behaviour can be attributed to an autogenous response to the prevailing flow conditions. Due to the prevailing fine sediment characteristics, bed material is readily set in motion and is being transported during the entire year. The existing design principles fail to address the initial morphological development after reconstruction. An evaluation of pre-set targets to realize water depth and flow velocity ranges shows the current procedures to be deficient. Based on this unfavourable evaluation, and the two-dimensional nature of habitat patterns needed to improve the conditions for stream organisms, we recommend to predict morphological developments as part of the design procedures for lowland stream restoration in the Netherlands.

Population history, phylogeography, and conservation genetics of the last Neotropical mega-herbivore, the lowland tapir (Tapirus terrestris)

PubMed Central

2010-01-01

Background Understanding the forces that shaped Neotropical diversity is central issue to explain tropical biodiversity and inform conservation action; yet few studies have examined large, widespread species. Lowland tapir (Tapirus terrrestris, Perissodactyla, Tapiridae) is the largest Neotropical herbivore whose ancestors arrived in South America during the Great American Biotic Interchange. A Pleistocene diversification is inferred for the genus Tapirus from the fossil record, but only two species survived the Pleistocene megafauna extinction. Here, we investigate the history of lowland tapir as revealed by variation at the mitochondrial gene Cytochrome b, compare it to the fossil data, and explore mechanisms that could have shaped the observed structure of current populations. Results Separate methodological approaches found mutually exclusive divergence times for lowland tapir, either in the late or in the early Pleistocene, although a late Pleistocene divergence is more in tune with the fossil record. Bayesian analysis favored mountain tapir (T. pinchaque) paraphyly in relation to lowland tapir over reciprocal monophyly, corroborating the inferences from the fossil data these species are sister taxa. A coalescent-based analysis rejected a null hypothesis of allopatric divergence, suggesting a complex history. Based on the geographic distribution of haplotypes we propose (i) a central role for western Amazonia in tapir diversification, with a key role of the ecological gradient along the transition between Andean subcloud forests and Amazon lowland forest, and (ii) that the Amazon river acted as an barrier to gene flow. Finally, the branching patterns and estimates based on nucleotide diversity indicate a population expansion after the Last Glacial Maximum. Conclusions This study is the first examining lowland tapir phylogeography. Climatic events at the end of the Pleistocene, parapatric speciation, divergence along the Andean foothill, and role of the Amazon

Population history, phylogeography, and conservation genetics of the last Neotropical mega-herbivore, the lowland tapir (Tapirus terrestris).

PubMed

de Thoisy, Benoit; da Silva, Anders Gonçalves; Ruiz-García, Manuel; Tapia, Andrés; Ramirez, Oswaldo; Arana, Margarita; Quse, Viviana; Paz-y-Miño, César; Tobler, Mathias; Pedraza, Carlos; Lavergne, Anne

2010-09-14

Understanding the forces that shaped Neotropical diversity is central issue to explain tropical biodiversity and inform conservation action; yet few studies have examined large, widespread species. Lowland tapir (Tapirus terrrestris, Perissodactyla, Tapiridae) is the largest Neotropical herbivore whose ancestors arrived in South America during the Great American Biotic Interchange. A Pleistocene diversification is inferred for the genus Tapirus from the fossil record, but only two species survived the Pleistocene megafauna extinction. Here, we investigate the history of lowland tapir as revealed by variation at the mitochondrial gene Cytochrome b, compare it to the fossil data, and explore mechanisms that could have shaped the observed structure of current populations. Separate methodological approaches found mutually exclusive divergence times for lowland tapir, either in the late or in the early Pleistocene, although a late Pleistocene divergence is more in tune with the fossil record. Bayesian analysis favored mountain tapir (T. pinchaque) paraphyly in relation to lowland tapir over reciprocal monophyly, corroborating the inferences from the fossil data these species are sister taxa. A coalescent-based analysis rejected a null hypothesis of allopatric divergence, suggesting a complex history. Based on the geographic distribution of haplotypes we propose (i) a central role for western Amazonia in tapir diversification, with a key role of the ecological gradient along the transition between Andean subcloud forests and Amazon lowland forest, and (ii) that the Amazon river acted as an barrier to gene flow. Finally, the branching patterns and estimates based on nucleotide diversity indicate a population expansion after the Last Glacial Maximum. This study is the first examining lowland tapir phylogeography. Climatic events at the end of the Pleistocene, parapatric speciation, divergence along the Andean foothill, and role of the Amazon river, have similarly shaped

Tracing oxidative weathering from the Andes to the lowland Amazon Basin using dissoved rhenium

NASA Astrophysics Data System (ADS)

Dellinger, M.; Hilton, R. G.; West, A. J.; Torres, M.; Burton, K. W.; Clark, K. E.; Baronas, J. J.

2016-12-01

Over long timescales (>105 yrs), the abundance of carbon dioxide (CO2) in the atmosphere is determined by the balance of the major carbon sources and sinks. Among the major carbon sources, the oxidation of organic carbon contained within sedimentary rocks ("petrogenic" carbon, or OCpetro) is thought to result in CO2 emission of similar magnitude to that released by volcanism. Rhenium (Re) has been proposed as a proxy for tracing OCpetro oxidation. Here we investigate the source, behavior and flux of dissolved and particulate rhenium (Re) in the Madre de Dios watershed (a major Andean tributary of the Amazon River) and the lowlands, aiming to characterize the behavior of Re in river water and quantify the flux of CO2 released by OCpetro oxidation. Measured Re concentrations in Andean rivers range from 0.07 to 1.55 ppt. In the Andes, Re concentration do not change significantly with water discharge, whereas in the lowlands, Re concentration decrease at high water discharge. Mass balance calculation show that more than 70% of the dissolved Re is sourced from the oxidation of OCpetro the Andes-floodplain system. We calculate dissolved Re flux over a hydrological year to estimate the rates of oxidative weathering, and the associated CO2 release from OCpetro. Rates are high in the Andean headwaters, consistent with estimates from other mountain rivers with similar rates of physical erosion. We find evidence that a significant amount of additional oxidation (Re flux) happens during floodplain transport. These results have important implications for improving our understanding of the source and processes controlling Re in rivers, and allowing us to quantify long-term OCpetro cycling in large river basins.

Widespread methanotrophic primary production in lowland chalk rivers.

PubMed

Shelley, Felicity; Grey, Jonathan; Trimmer, Mark

2014-05-22

Methane is oversaturated relative to the atmosphere in many rivers, yet its cycling and fate is poorly understood. While photosynthesis is the dominant source of autotrophic carbon to rivers, chemosynthesis and particularly methane oxidation could provide alternative sources of primary production where the riverbed is heavily shaded or at depth beneath the sediment surface. Here, we highlight geographically widespread methanotrophic carbon fixation within the gravel riverbeds of over 30 chalk rivers. In 15 of these, the potential for methane oxidation (methanotrophy) was also compared with photosynthesis. In addition, we performed detailed concurrent measurements of photosynthesis and methanotrophy in one large chalk river over a complete annual cycle, where we found methanotrophy to be active to at least 15 cm into the riverbed and to be strongly substrate limited. The seasonal trend in methanotrophic activity reflected that of the riverine methane concentrations, and thus the highest rates were measured in mid-summer. At the sediment surface, photosynthesis was limited by light for most of the year with heavy shading induced by dense beds of aquatic macrophytes. Across 15 rivers, in late summer, we conservatively calculated that net methanotrophy was equivalent to between 1% and 46% of benthic net photosynthetic production within the gravel riverbed, with a median value of 4%. Hence, riverbed chemosynthesis, coupled to the oxidation of methane, is widespread and significant in English chalk rivers.

Widespread methanotrophic primary production in lowland chalk rivers

PubMed Central

Shelley, Felicity; Grey, Jonathan; Trimmer, Mark

2014-01-01

Methane is oversaturated relative to the atmosphere in many rivers, yet its cycling and fate is poorly understood. While photosynthesis is the dominant source of autotrophic carbon to rivers, chemosynthesis and particularly methane oxidation could provide alternative sources of primary production where the riverbed is heavily shaded or at depth beneath the sediment surface. Here, we highlight geographically widespread methanotrophic carbon fixation within the gravel riverbeds of over 30 chalk rivers. In 15 of these, the potential for methane oxidation (methanotrophy) was also compared with photosynthesis. In addition, we performed detailed concurrent measurements of photosynthesis and methanotrophy in one large chalk river over a complete annual cycle, where we found methanotrophy to be active to at least 15 cm into the riverbed and to be strongly substrate limited. The seasonal trend in methanotrophic activity reflected that of the riverine methane concentrations, and thus the highest rates were measured in mid-summer. At the sediment surface, photosynthesis was limited by light for most of the year with heavy shading induced by dense beds of aquatic macrophytes. Across 15 rivers, in late summer, we conservatively calculated that net methanotrophy was equivalent to between 1% and 46% of benthic net photosynthetic production within the gravel riverbed, with a median value of 4%. Hence, riverbed chemosynthesis, coupled to the oxidation of methane, is widespread and significant in English chalk rivers. PMID:24695425

Lowland tapir (Tapirus terrestris) distribution, activity patterns and relative abundance in the Greater Madidi-Tambopata Landscape.

PubMed

Wallace, Robert; Ayala, Guido; Viscarra, Maria

2012-12-01

Lowland tapir distribution is described in northwestern Bolivia and southeastern Peru within the Greater Madidi-Tambopata Landscape, a priority Tapir Conservation Unit, using 1255 distribution points derived from camera trapping efforts, field research and interviews with park guards from 5 national protected areas and hunters from 19 local communities. A total of 392 independent camera trapping events from 14 camera trap surveys at 11 sites demonstrated the nocturnal and crepuscular activity patterns (86%) of the lowland tapir and provide 3 indices of relative abundance for spatial and temporal comparison. Capture rates for lowland tapirs were not significantly different between camera trapping stations placed on river beaches versus those placed in the forest. Lowland tapir capture rates were significantly higher in the national protected areas of the region versus indigenous territories and unprotected portions of the landscape. Capture rates through time suggested that lowland tapir populations are recovering within the Tuichi Valley, an area currently dedicated towards ecotourism activities, following the creation (1995) and subsequent implementation (1997) of the Madidi National Park in Bolivia. Based on our distributional data and published conservative estimates of population density, we calculated that this transboundary landscape holds an overall lowland tapir population of between 14 540 and 36 351 individuals, of which at least 24.3% are under protection from national and municipal parks. As such, the Greater Madidi-Tambopata Landscape should be considered a lowland tapir population stronghold and priority conservation efforts are discussed in order to maintain this population. © 2012 Wiley Publishing Asia Pty Ltd, ISZS and IOZ/CAS.

Assessing the suitable habitat for reintroduction of brown trout (Salmo trutta forma fario) in a lowland river: A modeling approach.

PubMed

Boets, Pieter; Gobeyn, Sacha; Dillen, Alain; Poelman, Eddy; Goethals, Peter L M

2018-05-01

Huge efforts have been made during the past decades to improve the water quality and to restore the physical habitat of rivers and streams in western Europe. This has led to an improvement in biological water quality and an increase in fish stocks in many countries. However, several rheophilic fish species such as brown trout are still categorized as vulnerable in lowland streams in Flanders (Belgium). In order to support cost-efficient restoration programs, habitat suitability modeling can be used. In this study, we developed an ensemble of habitat suitability models using metaheuristic algorithms to explore the importance of a large number of environmental variables, including chemical, physical, and hydromorphological characteristics to determine the suitable habitat for reintroduction of brown trout in the Zwalm River basin (Flanders, Belgium), which is included in the Habitats Directive. Mean stream velocity, water temperature, hiding opportunities, and presence of pools or riffles were identified as the most important variables determining the habitat suitability. Brown trout mainly preferred streams with a relatively high mean reach stream velocity (0.2-1 m/s), a low water temperature (7-15°C), and the presence of pools. The ensemble of models indicated that most of the tributaries and headwaters were suitable for the species. Synthesis and applications . Our results indicate that this modeling approach can be used to support river management, not only for brown trout but also for other species in similar geographical regions. Specifically for the Zwalm River basin, future restoration of the physical habitat, removal of the remaining migration barriers and the development of suitable spawning grounds could promote the successful restoration of brown trout.

Modelling hydrological processes and analysing water-related ecosystem services of Western Siberian lowland basins

NASA Astrophysics Data System (ADS)

Schmalz, Britta; Kiesel, Jens; Kruse, Marion; Pfannerstill, Matthias; Sheludkov, Artyom; Khoroshavin, Vitaliy; Veshkurseva, Tatyana; Müller, Felix; Fohrer, Nicola

2015-04-01

For discussing and planning sustainable land management of river basins, stakeholders need suitable information on spatio-temporal patterns of hydrological components and ecosystem services. The ecosystem services concept, i.e., services provided by ecosystems that contribute to human welfare benefits, contributes comprehensive information for sustainable river management. This study shows an approach to use ecohydrological modelling results for quantifying and assessing water-related ecosystem services in three lowland river basins in Western Siberia, a region which is of global significance in terms of carbon sequestration, agricultural production and biodiversity preservation. Using the ecohydrological model SWAT, the three basins Pyschma (16762 km²), Vagai (3348 km²) and Loktinka (373 km²) were modelled following a gradient from the landscape units taiga, pre-taiga to forest steppe. For a correct representation of the Siberian lowland hydrology, the consideration of snow melt and retention of surface runoff as well as the implementation of a second groundwater aquifer was of great importance. Good to satisfying model performances were obtained for the extreme hydrological conditions. The simulated SWAT output variables of different hydrological processes were used as indicators for the two regulating services water flow and erosion regulation. The model results were translated into a relative ecosystem service valuation scale. The resulting ecosystem service maps show different spatial and seasonal patterns. Although the high resolution modelling results are averaged out within the aggregated relative valuation scale, seasonal differences can be depicted: during snowmelt, low relevant regulation can be determined, especially for water flow regulation, but a very high relevant regulation was calculated for the vegetation period during summer and for the winter period. The SWAT model serves as a suitable quantification method for the assessment of water

Lowland-upland migration of sauropod dinosaurs during the Late Jurassic epoch.

PubMed

Fricke, Henry C; Hencecroth, Justin; Hoerner, Marie E

2011-10-26

Sauropod dinosaurs were the largest vertebrates ever to walk the Earth, and as mega-herbivores they were important parts of terrestrial ecosystems. In the Late Jurassic-aged Morrison depositional basin of western North America, these animals occupied lowland river-floodplain settings characterized by a seasonally dry climate. Massive herbivores with high nutritional and water needs could periodically experience nutritional and water stress under these conditions, and thus the common occurrence of sauropods in this basin has remained a paradox. Energetic arguments and mammalian analogues have been used to suggest that migration allowed sauropods access to food and water resources over a wide region or during times of drought or both, but there has been no direct support for these hypotheses. Here we compare oxygen isotope ratios (δ(18)O) of tooth-enamel carbonate from the sauropod Camarasaurus with those of ancient soil, lake and wetland (that is, 'authigenic') carbonates that formed in lowland settings. We demonstrate that certain populations of these animals did in fact undertake seasonal migrations of several hundred kilometres from lowland to upland environments. This ability to describe patterns of sauropod movement will help to elucidate the role that migration played in the ecology and evolution of gigantism of these and associated dinosaurs.

The water quality of the River Enborne, UK: insights from high-frequency monitoring

NASA Astrophysics Data System (ADS)

Halliday, Sarah; Skeffington, Richard; Wade, Andrew; Bowes, Mike; Gozzard, Emma; Palmer-Felgate, Elizabeth; Newman, Johnathan; Jarvie, Helen; Loewenthal, Matt

2014-05-01

The River Enborne is a rural lowland catchment, impacted by agricultural runoff, and septic tank and sewage treatment works (STWs) discharges. Between November 2009 and February 2012, the river was instrumented with in situ analytical equipment to take hourly measurements of total reactive phosphorus (TRP), using a Systea Micromac C; nitrate, using a Hach Lange Nitratax; and pH, chlorophyll, dissolved oxygen, conductivity, turbidity and water temperature, using a YSI 6600 Multi-parameter sonde. In addition, weekly 'grab samples' were also collected and analysed for a wide range of chemical determinands including major ions, nutrients, and trace elements. The catchment land use is largely agricultural, with wheat the dominant crop, and the average population density is 123 persons per sq. km. The river water is largely derived from calcareous groundwater, with a mean calcium concentration of 68.5 mg/l, and high nitrogen and phosphorus concentrations, with mean nitrate and TRP concentrations of 3.96 mg/l-N and 0.17 mg/l-P respectively. A mass-balance for the catchment demonstrated that agricultural fertiliser is the dominant source of annual loads of both nitrogen and phosphorus, accounting for 77 % and 84 % respectively. However, the concentration data show that sewage effluent discharges have a disproportionate effect on the river nitrogen and phosphorus dynamics, with the diurnal STW discharge signal discernable in the high-frequency nutrient dynamics. The nutrient dynamics and correlation structure of the data indicate a substantial contribution of groundwater and agricultural runoff to stream nitrate concentrations, whereas discharges from septic tank systems and sewage treatment works are a more important source of phosphorus. The high-frequency turbidity and conductivity dynamics reveal key information about the seasonal changes controlling the system dynamics, with marked differences in diurnal conductivity dynamics at the onset of riparian shading linked to

Late Holocene lowland fluvial archives and geoarchaeology: Utrecht's case study of Rhine river abandonment under Roman and Medieval settlement

NASA Astrophysics Data System (ADS)

van Dinter, Marieke; Cohen, Kim M.; Hoek, Wim Z.; Stouthamer, Esther; Jansma, Esther; Middelkoop, Hans

2017-06-01

Fluvial lowlands have become attractive human settling areas all around the world over the last few millennia. Because rivers kept changing their course and networks due to avulsion, the sedimentary sequences in these areas are archives of both fluvial geomorphological and archaeological development. We integrated geological and archaeological datasets to demonstrate the concurrence of the gradual abandonment of a major Rhine channel (Utrecht, The Netherlands), the development of human habitation in the area, and the interactions between them. The Utrecht case study highlights the stage-wise abandonment of a natural river channel, due to avulsion, coincident with intensifying human occupation in Roman and Early Medieval times (1st millennium AD). The analyses make maximum use of very rich data sets available for the study area and the tight age control that the geo-archaeological dataset facilitates, offering extra means of time-control to document the pacing of the abandonment process. This allows us to quantify change in river dimensions and meander style and to provide discharge estimates for successive stages of the abandonment phase over a 1000-year period of abandonment succession, from mature river to eventual Late Medieval overbuilt canal when the Rhine branch had lost even more discharge. Continued geomorphic development during this period - which includes the 'Dark Ages' (450-1000 AD) - appears to have been crucial in the development of Utrecht from Roman army fortress to Medieval ecclesial centre. The settlement dynamics in and around the city of Utrecht changed during the various phases of abandonment. In the bifurcating network of river branches forming the Rhine-Meuse delta, the main Rhine branch hosted the Roman limes military border and transport route. The Rhine- Vecht bifurcation at Utrecht provided an excellent location to raise a Roman fort. Continued geomorphic activity during abandonment in Early Medieval times was characterised by enhanced

Approaches to restoration of oak forests on farmed lowlands of the Mississippi river and its tributaries (Avances en la restauración de bosques de roble en tierras bajas agrícolas del Río Mississippi y sus tributaries)

Treesearch

E.S. Gardiner; D.C. Dey; John Stanturf; B.R. Lockhart

2010-01-01

The lowlands associated with the Mississippi River and its tributaries historically supported extensive broadleaf forests that were particularly rich in oak (Quercus spp.) species. Beginning in the 1700s, deforestation for agriculture substantially reduced the extent of the original forest, and fragmented the remainder into small parcels. More recently, declines in...

Looking for Similarities Between Lowland (Flash) Floods

NASA Astrophysics Data System (ADS)

Brauer, C.; Teuling, R.; Torfs, P.; Hobbelt, L.; Jansen, F.; Melsen, L.; Uijlenhoet, R.

2012-12-01

On 26 August 2010 the eastern part of The Netherlands and the bordering part of Germany were struck by a series of rainfall events. Over an area of 740 km2 more than 120 mm of rainfall were observed in 24 h. We investigated the unprecedented flash flood triggered by this exceptionally heavy rainfall event (return period > 1000 years) in the 6.5 km2 Hupsel Brook catchment, which has been the experimental watershed employed by Wageningen University since the 1960s. This study improved our understanding of the dynamics of such lowland flash floods (Brauer et al., 2011). These observations, however, only show how our experimental catchment behaved and the results cannot be extrapolated directly to different floods in other (neighboring) lowland catchments. Therefore, it is necessary to use the information collected in one well-monitored catchment in combination with data from other, less well monitored catchments to find common signatures which could describe the runoff response during a lowland flood as a function of catchment characteristics. Because of the large spatial extent of the rainfall event in August 2010, many brooks and rivers in the Netherlands and Germany flooded. With data from several catchments we investigated the influence of rainfall and catchment characteristics (such as slope, size and land use) on the reaction of discharge to rainfall. We also investigated the runoff response in these catchments during previous floods by analyzing the relation between storage and discharge and the recession curve. In addition to the flood in August 2010, two other floods occurred in The Netherlands in recently. The three floods occurred in different parts of the country, after different types of rainfall events and with different initial conditions. We selected several catchments during each flood to compare their response and find out if these cases are fundamentally different or that they were produced by the same underlying processes and can be treated in a

Large microplastic particles in sediments of tributaries of the River Thames, UK - Abundance, sources and methods for effective quantification.

PubMed

Horton, Alice A; Svendsen, Claus; Williams, Richard J; Spurgeon, David J; Lahive, Elma

2017-01-15

Sewage effluent input and population were chosen as predictors of microplastic presence in sediments at four sites in the River Thames basin (UK). Large microplastic particles (1mm-4mm) were extracted using a stepwise approach to include visual extraction, flotation and identification using Raman spectroscopy. Microplastics were found at all four sites. One site had significantly higher numbers of microplastics than other sites, average 66 particles 100g -1 , 91% of which were fragments. This site was downstream of a storm drain outfall receiving urban runoff; many of the fragments at this site were determined to be derived of thermoplastic road-surface marking paints. At the remaining three sites, fibres were the dominant particle type. The most common polymers identified included polypropylene, polyester and polyarylsulphone. This study describes two major new findings: presence of microplastic particles in a UK freshwater system and identification of road marking paints as a source of microplastics. This study is the first to quantify microplastics of any size in river sediments in the UK and links their presence to terrestrial sources including sewage and road marking paints. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Geomorphic response of rivers to glacial retreat and increasing peak flows downstream from Mount Rainier, Washington

NASA Astrophysics Data System (ADS)

Czuba, J. A.; Barnas, C. R.; Magirl, C. S.; Voss, F. D.

2010-12-01

On Mount Rainier, Washington, the National Park Service has documented widespread aggradation of as much as 10 m since the early 20th century, of rivers draining the glaciated stratovolcano. This rapid sedimentation appears to be related to glacial retreat and also may be a function of the increased magnitude and timing of peak flows that mobilize and transport sediment. We are conducting an assessment of the Puget Lowland rivers that drain Mount Rainier, 25-100 km downstream from the park boundary, to document the geomorphic response of the downstream reaches given the widespread aggradation upstream. These downstream reaches provide critical aquatic habitat for spawning and rearing of several species of salmonids, including endangered Chinook salmon and steelhead. Fluvial sedimentation can have both deleterious and beneficial effects on aquatic habitat depending on sediment particle size, river slope and width, and river management. To date, our work shows sedimentation of as much as 2 m between 1984 and 2009 in these lowland rivers. Aggradation rates that were calculated by comparing channel change at 156 cross sections, ranged between 4.8 and 9.1 cm/yr in reaches where rivers exit the mountain front and enter the lowland. Analysis of streamflow-gaging station data from throughout the watersheds draining Mount Rainier show rapid incision and aggradation, suggesting pulses of coarse-grained bedload may be moving down the mountainous rivers as kinetic waves. Preliminary results, however, seem to indicate that the rivers in the Puget Lowland have not yet experienced significant widespread sedimentation directly related to glacial retreat. Estimating the time of arrival of mobilized alluvium is a critical need for resource managers given the potential effects of sedimentation on river flood-conveyance capacity, fish habitat, and estuarine wetlands.

Occurrence and risk assessment of organophosphorus and brominated flame retardants in the River Aire (UK).

PubMed

Cristale, Joyce; Katsoyiannis, Athanasios; Sweetman, Andrew J; Jones, Kevin C; Lacorte, Silvia

2013-08-01

This study presents the occurrence and risk of PBDEs, new brominated and organophosphorus flame retardants along a river affected by urban and industrial pressures (River Aire, UK). Tris(2-choroethyl) phosphate (TCEP), tris(2-chloro-1-methylethyl) phosphate (TCPP), tris[2-chloro-1-(chloromethyl)ethyl] phosphate (TDCP) and triphenyl phosphate (TPhP) were detected in all samples, with TCPP present at the highest concentrations, ranging from 113 to 26,050 ng L⁻¹. BDE-209 was detected in most of the sampled sites, ranging from 17 to 295 ng L⁻¹, while hexabromobenzene (HBB) and pentabromoethyl benzene (PBEB) were seldom detected. A risk quotients based on predicted no effect concentrations (PNEC) and flame retardants water concentration proved significant risk for adverse effects for algae, Daphnia and fish in sites close to industrial and urban sewage discharges. This study provides a protocol for the risk estimation of priority and new generation flame retardants based on river concentrations and toxicological values. Copyright © 2013 Elsevier Ltd. All rights reserved.

Hydrogeochemical investigation of Küçük Menderes River coastal wetland, Selçuk-Izmir, Turkey

NASA Astrophysics Data System (ADS)

Somay, A. Melis; Gemici, Ünsal; Filiz, Sevki

2008-07-01

Küçük Menderes River forms a rich coastal wetland inside in the Selçuk plain. Three saline/brackish lakes, one swamp and Küçük Menderes River are these wetlands’ components. Alkaline-slightly alkaline type lakes are recharged from precipitation and karstic springs that discharge from marble-schist and marble-alluvium contacts in the northern and southern parts of the study area. Water types of the wetland are Na-Cl and Na-Ca-Mg-HCO3-Cl in both rainy and dry seasons. Both seawater intrusion and evaporation, as being the sources of the ions, justify the presence of Na-Cl, Na-SO4 and Cl-SO4, in the wetland water. Environmental isotopes were used to identify the relationship between wetland and groundwater in the Selçuk plain. The δ18O and δD composition of wetland area samples have changed between -6.42 to -4.56‰, and -36.40 to -23.80‰, respectively. The lakes and rivers are plotted on the mixing line by slope of 5.2 and these data indicate that wetland is affected from seawater intrusion. The recharge area that was sampled in order to compare the wetland has Ca-HCO3 water type with a neutral-slightly alkaline pH values and the main hydrogeochemical process is weathering the different types of silicates. Iron, manganese and selenium are the dominant minor ions due to the high biological activities and organic matters in the lakes. There are two contamination risks for this wetland: (1) waste disposal site and (2) water treatment plant where the purified waters are released into the river. EC, Al, As, Cd, Cu, Fe and Zn values exceed those of aquatic life standards. In the near future these sites will pose a danger for wetland wild life and surrounding irrigation water suppliers.

Dynamic modelling of five different phytoplankton groups in the River Thames (UK)

NASA Astrophysics Data System (ADS)

Bussi, Gianbattista; Whitehead, Paul; Bowes, Michael; Read, Daniel; Dadson, Simon

2015-04-01

Phytoplankton play a vital role in fluvial ecosystems, being a major producer of organic carbon, a food source for primary consumers and a relevant source of oxygen for many low-gradient rivers, but also a producer of potentially harmful toxins (e.g. cyanobacteria). For these reasons, the forecast and prevention of algal blooms is fundamental for the safe management of river systems. In this study, we developed a new process-based phytoplankton model for operational management and forecast of algal and cyanobacteria blooms subject to environmental change. The model is based on a mass-balance and it reproduces phytoplankton growth and death, taking into account the controlling effect played by water temperature, solar radiation, self-shading and dissolved phosphorus and silicon concentrations. The model was implemented in five reaches of the River Thames (UK) with a daily time step over a period of three years, and its results were compared to a novel dataset of cytometric data which includes community cell abundance of chlorophytes, diatoms, cyanobacteria, microcystis-like cyanobacteria and picoalgae. The model results were satisfactory in terms of fitting the observed data. A Multi-Objective General Sensitivity Analysis was also carried out in order to quantify model sensitivity to its parameters. It showed that the most influential parameters are phytoplankton growth and death rates, while phosphorus concentration showed little influence on phytoplankton growth, due to the high levels of phosphorus in the River Thames. The model was demonstrated to be a reliable tool to be used in algal bloom forecasting and management.

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.

Water resources of the Yellow Medicine River Watershed, Southwestern Minnesota

USGS Publications Warehouse

Novitzki, R.P.; Van Voast, Wayne A.; Jerabek, L.A.

1969-01-01

The Yellow Medicine and Minnesota Rivers are the major sources of surface water. For physiographic regions – Upland Plain, Slope, Lowland Plain, and Minnesota River Flood Plain – influence surface drainage, and the flow of ground water through the aquifers. The watershed comprises 1070 square miles, including the drainage basin of the Yellow Medicine River (665 square miles) and 405 square miles drained by small streams tributary to the Minnesota River.

Options for managing hypoxic blackwater events in river systems: a review.

PubMed

Kerr, Janice L; Baldwin, Darren S; Whitworth, Kerry L

2013-01-15

Blackwater events are characterised by a high concentration of dissolved organic carbon in the water column. They occur naturally in lowland rivers with forested floodplains and bring a variety of benefits to both aquatic and floodplain biota. However, particularly when accompanied by high temperatures, respiration of the organic carbon may cause blackwater to become hypoxic. This may lead to a range of lethal and sub-lethal effects on the aquatic biota. We review the current scientific knowledge concerning the management of blackwater and hypoxia, and examine how this knowledge may be applied to the management of hypoxic blackwater events in lowland river systems. A range of management options, which aim to either prevent the development of hypoxic blackwater or to reintroduce oxygen into deoxygenated waters, are reported. Mitigation options that may be applicable to lowland river systems include manipulating the season and magnitude of floods in regulated rivers, increasing roughness in flow paths, establishing oxygenated refugia for aquatic biota and introducing hydraulic structures that promote turbulence and re-aeration. With climatic changes trending towards a scenario where extreme events leading to the development of hypoxic blackwater are more probable, it is now vital to validate and optimise management options on local and regional scales and work towards closing knowledge gaps. With judicious management of regulated rivers, it is possible to minimise the impacts of hypoxic flows while preserving the benefits brought to floodplain and river ecosystems by seasonal flooding and carbon exchange. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Modelling climate change, land-use change and phosphorus reduction impacts on phytoplankton in the River Thames (UK)

NASA Astrophysics Data System (ADS)

Bussi, Gianbattista; Whitehead, Paul; Dadson, Simon

2016-04-01

In this study, we assess the impact of changes in precipitation and temperature on the phytoplankton concentration of the River Thames (UK) by means of a physically-based model. A scenario-neutral approach was employed to evaluate the effects of climate variability on flow, phosphorus concentration and phytoplankton concentration. In particular, the impact of uniform changes in precipitation and temperature on five groups of phytoplankton (diatoms and large chlorophytes, other chlorophytes, picoalgae, Microcystis-like cyanobacteria and other cyanobacteria) was assessed under three different land-use/land-management scenarios (1 - current land use and phosphorus reduction practices; 2 - expansion of agricultural land and current phosphorus reduction practices; 3 - expansion of agricultural land and optimal phosphorus reduction practices). The model results were assessed within the framework of future climate projections, using the UK Climate Projections 09 (UKCP09) for the 2030s. The results of the model demonstrate that an increase in average phytoplankton concentration due to climate change is highly likely to occur, and its magnitude varies depending on the river reach. Cyanobacteria show significant increases under future climate change and land-use change. An expansion of intensive agriculture accentuates the growth in phytoplankton, especially in the upper reaches of the River Thames. However, an optimal phosphorus removal mitigation strategy, which combines reduction of fertiliser application and phosphorus removal from wastewater, can help to reduce this increase in phytoplankton concentration, and in some cases, compensate for the effect of rising temperature.

Eddy covariance flux measurements of net ecosystem carbon dioxide exchange from a lowland peatland flux tower network in England and Wales

NASA Astrophysics Data System (ADS)

Morrison, Ross; Balzter, Heiko; Burden, Annette; Callaghan, Nathan; Cumming, Alenander; Dixon, Simon; Evans, Jonathan; Kaduk, Joerg; Page, Susan; Pan, Gong; Rayment, Mark; Ridley, Luke; Rylett, Daniel; Worrall, Fred; Evans, Christopher

2016-04-01

Peatlands store disproportionately large amounts of soil carbon relative to other terrestrial ecosystems. Over recent decades, the large amount of carbon stored as peat has proved vulnerable to a range of land use pressures as well as the increasing impacts of climate change. In temperate Europe and elsewhere, large tracts of lowland peatland have been drained and converted to agricultural land use. Such changes have resulted in widespread losses of lowland peatland habitat, land subsidence across extensive areas and the transfer of historically accumulated soil carbon to the atmosphere as carbon dioxide (CO2). More recently, there has been growth in activities aiming to reduce these impacts through improved land management and peatland restoration. Despite a long history of productive land use and management, the magnitude and controls on greenhouse gas emissions from lowland peatland environments remain poorly quantified. Here, results of surface-atmosphere measurements of net ecosystem CO2 exchange (NEE) from a network of seven eddy covariance (EC) flux towers located at a range of lowland peatland ecosystems across the United Kingdom (UK) are presented. This spatially-dense peatland flux tower network forms part of a wider observation programme aiming to quantify carbon, water and greenhouse gas balances for lowland peatlands across the UK. EC measurements totalling over seventeen site years were obtained at sites exhibiting large differences in vegetation cover, hydrological functioning and land management. The sites in the network show remarkable spatial and temporal variability in NEE. Across sites, annual NEE ranged from a net sink of -194 ±38 g CO2-C m-2 yr-1 to a net source of 784±70 g CO2-C m-2 yr-1. The results suggest that semi-natural sites remain net sinks for atmospheric CO2. Sites that are drained for intensive agricultural production range from a small net sink to the largest observed source for atmospheric CO2 within the flux tower network

Morphological assessment of reconstructed lowland streams in the Netherlands

NASA Astrophysics Data System (ADS)

Eekhout, Joris P. C.; Hoitink, Antonius J. F.; de Brouwer, Jan H. F.; Verdonschot, Piet F. M.

2015-07-01

Channelisation measures taken halfway the 20th century have had destructive consequences for the diversity of the ecology in the majority of the lowland streams in countries such as the Netherlands. Re-meandering is the common practice in restoring these lowland streams. Three reconstructed streams were monitored during the initial two years after construction of a new channel. The monitoring program included morphological surveys, sediment sampling, habitat pattern surveys, and discharge and water level measurements. Adjustments of the longitudinal bed profile formed the main morphological response. These adjustments were most likely caused by a lack of longitudinal connectivity of the streams as a whole, interrupting transport of sediment at locations of weirs and culverts. Bank erosion was observed only in a limited number of channel bends, and was often related to floodplain heterogeneity. Longitudinal channel bed adjustments and bank erosion were mainly caused by exogenous influences. In channel bends, the cross-sectional shape transformed from trapezoidal to the typical asymmetrical shape as found in meandering rivers. This behaviour can be attributed to an autogenous response to the prevailing flow conditions. Due to the prevailing fine sediment characteristics, bed material is readily set in motion and is being transported during the entire year. The existing design principles fail to address the initial morphological development after reconstruction. An evaluation of pre-set targets to realise water depth and flow velocity ranges shows the current procedures to be deficient. Based on this unfavourable evaluation, and the two-dimensional nature of habitat patterns needed to improve the conditions for stream organisms, we recommend to predict morphological developments as part of the design procedures for lowland stream restoration in the Netherlands.

Temporal variability of micro-organic contaminants in lowland chalk catchments: New insights into contaminant sources and hydrological processes.

PubMed

Manamsa, K; Lapworth, D J; Stuart, M E

2016-10-15

This paper explores the temporal variation of a broad suite of micro organic (MO) compounds within hydrologically linked compartments of a lowland Chalk catchment, the most important drinking water aquifer in the UK. It presents an assessment of results from relatively high frequency monitoring at a well-characterised site, including the type and concentrations of compounds detected and how they change under different hydrological conditions including exceptionally high groundwater levels and river flow conditions during 2014 and subsequent recovery. This study shows for the first time that within the Chalk groundwater there can be a greater diversity of the MOs compared to surface waters. Within the Chalk 26 different compounds were detected over the duration of the study compared to 17 in the surface water. Plasticisers (0.06-39μg/L) were found to dominate in the Chalk groundwater on 5 visits (38.4%) accounting for 14.5% of detections but contributing highest concentrations whilst other compounds dominated in the surface water. Trichloroethene and atrazine were among the most frequently detected compounds. The limit for the total pesticide concentration detected did not exceed EU/UK prescribed concentration values for drinking water. Emerging organic compounds such as caffeine, which currently do not have water quality limits, were also detected. The low numbers of compounds found within the hyporheic zone highlight the role of this transient interface in the attenuation and breakdown of the MOs, and provision of an important ecosystem service. Copyright © 2016 British Geological Survey, NERC. Published by Elsevier B.V. All rights reserved.

Evaluating sourcing and fluvial integration of plant wax biomarkers from the Peruvian Andes to Amazonian lowlands

NASA Astrophysics Data System (ADS)

Wu, M. S.; Feakins, S. J.; Ponton, C.; West, A. J.; Galy, V.

2017-12-01

The carbon and hydrogen isotopic compositions (respectively δ13C and δD) of plant wax biomarkers have been widely used to reconstruct past climate and environment. To understand how leaf waxes are sourced within a river catchment, and how their isotopic signature is transferred from source to sink, we study δ13C and δD of C29 n-alkanes and C30 n-alkanoic acids in the Madre de Dios River catchment along the eastern flank of the Peruvian Andes. We sampled soils across a 3.5km elevation transect and find gradients in δ13Cwax (ca. +1.5‰/km) and δDwax (ca. -10 ‰/km) similar to gradients in tree canopy leaves (Feakins et al., 2016 GCA; Wu et al., 2017 GCA). We also collected river suspended sediment samples along the Madre de Dios River and its tributaries, which together drain an area of 75,400 km2 and 6 km of elevation. We utilize soil data and a digital elevation model to construct isoscapes, delineate catchments for each river sampling location, predict river values assuming spatial uniform integration, and compare our predictions with observed values. Although both compounds generally follow isotopic gradients defined by catchment elevations, the dual isotope and compound-class comparison reveals additional processes. For C30 n-alkanoic acid we find an up to 1km lower-than-expected catchment signal, indicating degradation of upland contributions in transit and replacement with lowland inputs. In contrast, mountain-front river locations are susceptible to upland-biases (up to 1km higher sourcing) in C29 n-alkane sourcing, likely due to enhanced erosion and higher leaf wax stock in Andean soil compared to the lowland, and greater persistence of n-alkanes than n-alkanoic acids. For both compounds, the bias is eliminated with several hundred km of river transit across the floodplain. In one location, we identify significant petrogenic contamination of n-alkanes but not n-alkanoic acids. These results indicate the power in combining dual compound classes and

New challenges for the management of plant nutrients and pathogens in the Waikato River, New Zealand.

PubMed

Vant, W N

2001-01-01

The water quality of the Waikato River is currently much better than it was in the 1950s. Major improvements in the treatment of the sewage and industrial wastewaters which are discharged to the river mean that levels of indicator bacteria in the lower reaches of the river are now many times lower than in the past. Eve so, conditions are still not suitable for swimming, and blue-green algal blooms occur at times. Non-point or diffuse sources of contaminants now dominate the nutrient and pathogens budgets. Progressively-intensifying farming, particularly in lowland areas, is thought to contribute the majority of the contaminants found in the river. Future improvements in water quality will therefore depend more on activities like changes to farming practice--such as retiring the riparian margins of lowland tributaries of the river--than on further advances in wastewater treatment.

Hydrology and phosphorus transport simulation in a lowland polder by a coupled modeling system.

PubMed

Yan, Renhua; Huang, Jiacong; Li, Lingling; Gao, Junfeng

2017-08-01

Modeling the rain-runoff processes and phosphorus transport processes in lowland polders is critical in finding reasonable measures to alleviate the eutrophication problem of downstream rivers and lakes. This study develops a lowland Polder Hydrology and Phosphorus modeling System (PHPS) by coupling the WALRUS-paddy model and an improved phosphorus module of a Phosphorus Dynamic model for lowland Polder systems (PDP). It considers some important hydrological characteristics, such as groundwater-unsaturated zone coupling, groundwater-surface water feedback, human-controlled irrigation and discharge, and detailed physical and biochemical cycles of phosphorus in surface water. The application of the model in the Jianwei polder shows that the simulated phosphorus matches well with the measured values. The high precision of this model combined with its low input data requirement and efficient computation make it practical and easy to the water resources management of Chinese polders. Parameter sensitivity analysis demonstrates that K uptake , c Q2 , c W1 , and c Q1 exert a significant effect on the modeled results, whereas K resuspensionMax , K settling , and K mineralization have little effect on the modeled total phosphorus. Among the three types of uncertainties (i.e., parameter, initial condition, and forcing uncertainties), forcing uncertainty produces the strongest effect on the simulated phosphorus. Based on the analysis result of annual phosphorus balance when considering the high import from irrigation and fertilization, lowland polder is capable of retaining phosphorus and reducing phosphorus export to surrounding aquatic ecosystems because of their special hydrological regulation regime. Copyright © 2016 Elsevier Ltd. All rights reserved.

The susceptibility of large river basins to orogenic and climatic drivers

NASA Astrophysics Data System (ADS)

Haedke, Hanna; Wittmann, Hella; von Blanckenburg, Friedhelm

2017-04-01

Large rivers are known to buffer pulses in sediment production driven by changes in climate as sediment is transported through lowlands. Our new dataset of in situ cosmogenic nuclide concentration and chemical composition of 62 sandy bedload samples from the world largest rivers integrates over 25% of Earth's terrestrial surface, distributed over a variety of climatic zones across all continents, and represents the millennial-scale denudation rate of the sediment's source area. We can show that these denudation rates do not respond to climatic forcing, but faithfully record orogenic forcing, when analyzed with respective variables representing orogeny (strain rate, relief, bouguer anomaly, free-air anomaly), and climate (runoff, temperature, precipitation) and basin properties (floodplain response time, drainage area). In contrast to this orogenic forcing of denudation rates, elemental bedload chemistry from the fine-grained portion of the same samples correlates with climate-related variables (precipitation, runoff) and floodplain response times. It is also well-known from previous compilations of river-gauged sediment loads that the short-term basin-integrated sediment export is also climatically controlled. The chemical composition of detrital sediment shows a climate control that can originate in the rivers source area, but this signal is likely overprinted during transfer through the lowlands because we also find correlation with floodplain response times. At the same time, cosmogenic nuclides robustly preserve the orogenic forcing of the source area denudation signal through of the floodplain buffer. Conversely, previous global compilations of cosmogenic nuclides in small river basins show the preservation of climate drivers in their analysis, but these are buffered in large lowland rivers. Hence, we can confirm the assumption that cosmogenic nuclides in large rivers are poorly susceptible to climate changes, but are at the same time highly suited to detect

Nitrogen speciation and phosphorus fractionation dynamics in a lowland Chalk catchment.

PubMed

Yates, C A; Johnes, P J

2013-02-01

A detailed analysis of temporal and spatial trends in nitrogen (N) speciation and phosphorus (P) fractionation in the Wylye, a lowland Chalk sub-catchment of the Hampshire Avon, UK is presented, identifying the sources contributing to nutrient enrichment, and temporal variability in the fractionation of nutrients in transit from headwaters to lower reaches of the river. Samples were collected weekly from ten monitoring stations with daily sampling at three further sites over one year, and monthly inorganic N and total reactive P (TRP) concentrations at three of the ten weekly monitoring stations over a ten year period are also presented. The data indicate significant daily and seasonal variation in nutrient fractionation in the water column, resulting from plant uptake of dissolved organic and inorganic nutrient fractions in the summer months, increased delivery of both N and P from diffuse sources in the autumn to winter period and during high flow events, and lack of dilution of point source discharges to the Wylye from septic tank, small package Sewage Treatment Works (STW) and urban Waste Water Treatment Works (WwTW) during the summer low flow period. Weekly data show that contributing source areas vary along the river with headwater N and P strongly influenced by diffuse inorganic N and particulate P fluxes, and SRP and organic-rich point source contributions from STW and WwTW having a greater influence in the lower reaches. Long-term data show a decrease in TRP concentrations at all three monitoring stations, with the most pronounced decrease occurring downstream from Warminster WwTW, following the introduction of P stripping at the works in 2001. Inorganic N demonstrates no statistically significant change over the ten year period of record in the rural headwaters, but an increase in the lower reaches downstream from the WwTW which may be due to urban expansion in the lower catchment. Copyright © 2012 Elsevier B.V. All rights reserved.

Yazoo River Basin (Lower Mississippi River) Hydrologic Observatory

NASA Astrophysics Data System (ADS)

Cheng, A.; Davidson, G.; Altinakar, M.; Holt, R.

2004-12-01

The proposed Yazoo River Basin Hydrologic Observatory consists of the 34,000 square km Yazoo River watershed in northwestern Mississippi and a 320 km segment of the Mississippi River separated from the watershed by a manmade levee. Discharge from the basin flows from the Yazoo River into the Mississippi River north of Vicksburg, MS. Major streams within the basin include the Yazoo, Tallahatchie, Yalobusha, Coldwater, Yocona, and Big Sunflower Rivers. Four large flood control reservoirs (Arkabutla, Enid, Sardis, and Grenada) and two national forests (Delta and Holly Springs) are also located within the basin. The watershed is divided between upland forested hills and intensively cultivated lowlands. The lowland area, locally known as the "Delta", lies on the ancestral floodplain of the Mississippi River. Flooding by the Mississippi River was once a common event, but is now limited by the levee system. Abundant wetlands occupy abandoned stream channels throughout the Delta. The Yazoo River Basin has many unique features that make it an attractive site for an Hydrologic Observatory. Example features and issues of scientific interest include: 1) Extensive system of levees which have altered recharge to the regional aquifer, shifted population centers, and created backwater flooding areas. 2) Abundant wetlands with a century-long history of response to agricultural sediment and chemical fluxes. 3) Erosion of upland streams, and stream sediment loads that are the highest in the nation. 4) Groundwater mining in spite of abundant precipitation due to a regional surface clay layer that limits infiltration. 5) A history of agricultural Best Management Practices enabling evaluation of the effectiveness of such measures. 6) Large scale catfish farming with heavy reliance on groundwater. 7) Near enough to the Gulf coast to be impacted by hurricane events. 8) Already existing network of monitoring stations for stream flow, sediment-load, and weather, including complete coverage

A Stochastic Water Balance Framework for Lowland Watersheds

NASA Astrophysics Data System (ADS)

Thompson, Sally; MacVean, Lissa; Sivapalan, Murugesu

2017-11-01

The water balance dynamics in lowland watersheds are influenced not only by local hydroclimatic controls on energy and water availability, but also by imports of water from the upstream watershed. These imports result in a stochastic extent of inundation in lowland watersheds that is determined by the local flood regime, watershed topography, and the rate of loss processes such as drainage and evaporation. Thus, lowland watershed water balances depend on two stochastic processes—rainfall and local inundation dynamics. Lowlands are high productivity environments that are disproportionately associated with urbanization, high productivity agriculture, biodiversity, and flood risk. Consequently, they are being rapidly altered by human development—generally with clear economic and social motivation—but also with significant trade-offs in ecosystem services provision, directly related to changes in the components and variability of the lowland water balance. We present a stochastic framework to assess the lowland water balance and its sensitivity to two common human interventions—replacement of native vegetation with alternative land uses, and construction of local flood protection levees. By providing analytical solutions for the mean and PDF of the water balance components, the proposed framework provides a mechanism to connect human interventions to hydrologic outcomes, and, in conjunction with ecosystem service production estimates, to evaluate trade-offs associated with lowland watershed development.

Comparison of direct outflow calculated by modified SCS-CN methods for mountainous and highland catchments in upper Vistula Basin, Poland and lowland catchment in South Carolina, U.S.A

Treesearch

A. Walega; A. Cupak; D.M. Amatya; E. Drozdzal

2017-01-01

The aim of the study is to compare direct outflow from storm events estimated using modifications of original SCS-CN procedure. The study was conducted in a mountainous catchment of Kamienica River and a highland catchment draining Stobnica River located in Upper Vistula water region, both in Poland, and a headwater lowland watershed WS80 located at the Santee...

Volume 90, Issue1 (February 2005)Articles in the Current Issue:Original PaperSeasonal Dynamics of Benthic and Planktonic Algae in a Nutrient-Rich Lowland River (Spree, Germany)

NASA Astrophysics Data System (ADS)

Werner, Petra; Köhler, Jan

2005-02-01

We studied chlorophyll a (chl. a), biovolume and species composition of benthic algae and phytoplankton in the eutrophic lower River Spree in 1996. The chl. a concentration was estimated as 3.5 (2.7-4.5) μg/cm2 for epipsammon, 9.4 (7.4-11.9) μg/cm2 for epipelon and 6.7 (5.7-7.8) μg/cm2 for the epilithon (median and 95% C. L.). The mean total biomass of benthic algae was significantly higher (6.0 μg chl. a/cm2) than the areal chl. a content of the pelagic zone (1.6 μg chl. a/cm²). Although certain phytoplankton taxa were abundant in the periphyton, benthic taxa generally dominated the assemblages. Seasonal dynamics of benthic algae were probably controlled by light and nitrate supply (sand), discharge fluctuations (sand, mud) and invertebrate grazing (stones). This paper shows the importance of benthic algae even in phytoplankton-rich lowland rivers with sandy or muddy sediments.

Responses of aquatic organisms to metal pollution in a lowland river in Flanders: a comparison of diatoms and macroinvertebrates.

PubMed

De Jonge, Maarten; Van de Vijver, Bart; Blust, Ronny; Bervoets, Lieven

2008-12-15

sediment. This study indicated that to assess the effect of metal pollution in lowland rivers, the combined use of macroinvertebrates and diatoms is more appropriate than the use of both biota separately.

Formation of transformation products from wastewater-derived pharmaceuticals in an urban lowland stream

NASA Astrophysics Data System (ADS)

Jäger, A.; Posselt, M.; Schaper, J. L.; Lewandowski, J.

2017-12-01

Not only transport, but especially transformation of polar organic micropollutants in urban streams is of increasing concern for urban water management. While concentrations of pharmaceuticals might decrease down the river, concentrations of their more persistent metabolites potentially increase due to microbial transformation. The river Erpe, an urban lowland stream located in Berlin, Germany, receives high loads of treated waste water. A Lagrangian sampling scheme was applied to follow water parcels 4.7 km down the river using the diurnal fluctuations of electrical conductivity as an intrinsic conservative tracer. Each experiment comprised of hourly sample collection for two days, accompanied by discharge measurements and continuous data logging of electrical conductivity. The fate of pharmaceuticals and their transformation products was compared between seasons (April and June) and before and after a stretch of the river has been cleared of macrophytes. The set of micropollutants was analysed by a newly developed direct injection-UHPLC-MS/MS method. The behaviour of individual micropollutants was compound-specific. Valsartan and metoprolol were attenuated by up to 18% of their original concentration. At the same time the transformation products valsartan acid and metoprolol acid increased in concentration by up to 24%. Their formation along the reach varied between seasons and was influenced by macrophyte removal. The findings indicate that the self-purification capacity of urban rivers is variable in time and sensitive to changes in the river's hydrological regime and emphasize the relevance of formation of transformation products in urban rivers.

Sewage effluent clean-up reduces phosphorus but not phytoplankton in lowland chalk stream (River Kennet, UK) impacted by water mixing from adjacent canal.

PubMed

Neal, Colin; Martin, Ellie; Neal, Margaret; Hallett, John; Wickham, Heather D; Harman, Sarah A; Armstrong, Linda K; Bowes, Mike J; Wade, Andrew J; Keay, David

2010-10-15

Information is provided on phosphorus in the River Kennet and the adjacent Kennet and Avon Canal in southern England to assess their interactions and the changes following phosphorus reductions in sewage treatment work (STW) effluent inputs. A step reduction in soluble reactive phosphorus (SRP) concentration within the effluent (5 to 13 fold) was observed from several STWs discharging to the river in the mid-2000s. This translated to over halving of SRP concentrations within the lower Kennet. Lower Kennet SRP concentrations change from being highest under base-flow to highest under storm-flow conditions. This represented a major shift from direct effluent inputs to a within-catchment source dominated system characteristic of the upper part to the catchment. Average SRP concentrations in the lower Kennet reduced over time towards the target for good water quality. Critically, there was no corresponding reduction in chlorophyll-a concentration, the waters remaining eutrophic when set against standards for lakes. Following the up gradient input of the main water and SRP source (Wilton Water), SRP concentrations in the canal reduced down gradient to below detection limits at times near its junction with the Kennet downstream. However, chlorophyll concentrations in the canal were in an order of magnitude higher than in the river. This probably resulted from long water residence times and higher temperatures promoting progressive algal and suspended sediment generations that consumed SRP. The canal acted as a point source for sediment, algae and total phosphorus to the river especially during the summer months when boat traffic disturbed the canal's bottom sediments and the locks were being regularly opened. The short-term dynamics of this transfer was complex. For the canal and the supply source at Wilton Water, conditions remained hypertrophic when set against standards for lakes even when SRP concentrations were extremely low. Copyright © 2010 Elsevier B.V. All

Fishes of the big muddy river drainage with emphasis on historical changes

Treesearch

Brooks M. Burr; Melvin L. Warren

1999-01-01

The Big Muddy River, a lowland stream located in southwestern Illinois and draining an area of about 6,182 km2, contains a moderately diverse fish fauna of 106 species. The river is properly named, as the mainstem carried historically and continues to transport great quantities of silt. Historically, a large portion of the watershed was wooded,...

Future efficiency of run of the river hydropower schemes based on climate change scenarios: case study in UK catchments

NASA Astrophysics Data System (ADS)

Pasten Zapata, Ernesto; Moggridge, Helen; Jones, Julie; Widmann, Martin

2017-04-01

Run-of-the-River (ROR) hydropower schemes are expected to be importantly affected by climate change as they rely in the availability of river flow to generate energy. As temperature and precipitation are expected to vary in the future, the hydrological cycle will also undergo changes. Therefore, climate models based on complex physical atmospheric interactions have been developed to simulate future climate scenarios considering the atmosphere's greenhouse gas concentrations. These scenarios are classified according to the Representative Concentration Pathways (RCP) that are generated according to the concentration of greenhouse gases. This study evaluates possible scenarios for selected ROR hydropower schemes within the UK, considering three different RCPs: 2.6, 4.5 and 8.5 W/m2 for 2100 relative to pre-industrial values. The study sites cover different climate, land cover, topographic and hydropower scheme characteristics representative of the UK's heterogeneity. Precipitation and temperature outputs from state-of-the-art Regional Climate Models (RCMs) from the Euro-CORDEX project are used as input for a HEC-HMS hydrological model to simulate the future river flow available. Both uncorrected and bias-corrected RCM simulations are analyzed. The results of this project provide an insight of the possible effects of climate change towards the generation of power from the ROR hydropower schemes according to the different RCP scenarios and contrasts the results obtained from uncorrected and bias-corrected RCMs. This analysis can aid on the adaptation to climate change as well as the planning of future ROR schemes in the region.

Nested heat tracer experiments for identifying heterogeneity of aquifer-river exchange at multiple scales

NASA Astrophysics Data System (ADS)

Krause, Stefan; Hannah, David; Blume, Theresa; Angermann, Lisa; Lewandowski, Joerg; Cassidy, Nigel

2016-04-01

This study presents the nested application of three heat tracing methods for identifying aquifer-river exchange fluxes at multiple scales ranging from centimeter to stream reach-scale. The investigations focus on a UK lowland river where hotspots of redox-reactivity were found to coincide with locations of increased streambed residence times underneath flow confining streambed peat and clay structures. In order to identify the spatial extend and patterns of reactivity hot spots associated with these streambed structures, reach-scale patterns of aquifer-river exchange fluxes have been analysed by Fibre-Optic Distributed Temperature Sensing (FO-DTS) along a cable buried in the streambed of a 250 m reach in combination with 2D thermocouple arrays in a 12 m long pool-riffle-pool sequence and small-scale heat pulse injections for tracing shallow hyporheic flow paths within the uppermost 20cm streambed sediments. FO-DTS observed streambed temperature anomalies caused by the mixing of different temperatures of GW and SW end-members were used to infer information on exchange fluxes at the aquifer-river interface. FO-DTS survey results indicate that patterns of up to 2C colder (Summer) and 3.5C warmer (Winter) temperatures in investigated streambed sediments can be attributed to fast GW up-welling in sandy and gravely sediments. Contrasting conditions were found at locations where streambed temperatures equal SW temperatures and GW-SW exchange was inhibited by the existence of peat or clay lenses within the streambed. FO-DTS observations of regional GW up-welling patterns were complemented by heat pulse injection experiments which provided essential information of the shallow aquifer- river exchange fluxes and confirmed increased SW infiltration and lateral flow in riffle crests and at locations with highly conductive streambed sediments above flow confining low conductivity structures. The propagation of diurnal temperature oscillations from the surface to streambed depths

Modeling a network of turloughs in lowland karst

NASA Astrophysics Data System (ADS)

Gill, L. W.; Naughton, O.; Johnston, P. M.

2013-06-01

In lowland karst areas of Ireland topographic depressions which get intermittently flooded on an annual cycle via groundwater sources are termed turloughs. These are sites of high ecological interest as they have communities and substrate characteristic of wetlands. The flooding in many turlough basins is due to insufficient capacity of the underground karst system to take increased flows following excessive precipitation events, causing the conduit-type network to surcharge. Continuous water level measurements have been taken in five linked turloughs in the lowland karst area of south Galway over a 3 year period. These water level fluctuations, in conjunction with river inputs and precipitation, were then used to elucidate the hydrogeological controls forming the hydraulic system beneath the ground. A model of the karst network has been developed using a pipe network model with the turloughs represented as ponds. The contribution to the karst network from diffuse flow through the epikarst via the matrix and fracture flow has also been modeled using a combination of an infiltration module and network of permeable pipes. The final model was calibrated against two separate hydrological years and in general provided a good simulation for all of the turloughs water levels particularly for the year with one main filling event. The model also accurately picked up the tidal response observed in these turloughs at shallow depths. The model has been used to predict the groundwater discharge to the coast via the main spring which had not heretofore been possible to measure, being below the sea level.

Characterization of meter-scale spatial variability of riverbed hydraulic conductivity in a lowland river (Aa River, Belgium)

NASA Astrophysics Data System (ADS)

Ghysels, Gert; Benoit, Sien; Awol, Henock; Jensen, Evan Patrick; Debele Tolche, Abebe; Anibas, Christian; Huysmans, Marijke

2018-04-01

An improved general understanding of riverbed heterogeneity is of importance for all groundwater modeling studies that include river-aquifer interaction processes. Riverbed hydraulic conductivity (K) is one of the main factors controlling river-aquifer exchange fluxes. However, the meter-scale spatial variability of riverbed K has not been adequately mapped as of yet. This study aims to fill this void by combining an extensive field measurement campaign focusing on both horizontal and vertical riverbed K with a detailed geostatistical analysis of the meter-scale spatial variability of riverbed K . In total, 220 slug tests and 45 standpipe tests were performed at two test sites along the Belgian Aa River. Omnidirectional and directional variograms (along and across the river) were calculated. Both horizontal and vertical riverbed K vary over several orders of magnitude and show significant meter-scale spatial variation. Horizontal K shows a bimodal distribution. Elongated zones of high horizontal K along the river course are observed at both sections, indicating a link between riverbed structures, depositional environment and flow regime. Vertical K is lognormally distributed and its spatial variability is mainly governed by the presence and thickness of a low permeable organic layer at the top of the riverbed. The absence of this layer in the center of the river leads to high vertical K and is related to scouring of the riverbed by high discharge events. Variograms of both horizontal and vertical K show a clear directional anisotropy with ranges along the river being twice as large as those across the river.

Hyporheic flow patterns in relation to large river floodplain attributes

EPA Science Inventory

Field-calibrated models of hyporheic flow have emphasized low-order headwater systems. In many cases, however, hyporheic flow in large lowland river floodplains may be an important contributor to ecosystem services such as maintenance of water quality and habitat. In this study, ...

Impacts of climate change, land-use change and phosphorus reduction on phytoplankton in the River Thames (UK).

PubMed

Bussi, Gianbattista; Whitehead, Paul G; Bowes, Michael J; Read, Daniel S; Prudhomme, Christel; Dadson, Simon J

2016-12-01

Potential increases of phytoplankton concentrations in river systems due to global warming and changing climate could pose a serious threat to the anthropogenic use of surface waters. Nevertheless, the extent of the effect of climatic alterations on phytoplankton concentrations in river systems has not yet been analysed in detail. In this study, we assess the impact of a change in precipitation and temperature on river phytoplankton concentration by means of a physically-based model. A scenario-neutral methodology has been employed to evaluate the effects of climate alterations on flow, phosphorus concentration and phytoplankton concentration of the River Thames (southern England). In particular, five groups of phytoplankton are considered, representing a range of size classes and pigment phenotypes, under three different land-use/land-management scenarios to assess their impact on phytoplankton population levels. The model results are evaluated within the framework of future climate projections, using the UK Climate Projections 09 (UKCP09) for the 2030s. The results of the model demonstrate that an increase in average phytoplankton concentration due to climate change is highly likely to occur, with the magnitude varying depending on the location along the River Thames. Cyanobacteria show significant increases under future climate change and land use change. An expansion of intensive agriculture accentuates the growth in phytoplankton, especially in the upper reaches of the River Thames. However, an optimal phosphorus removal mitigation strategy, which combines reduction of fertiliser application and phosphorus removal from wastewater, can help to reduce this increase in phytoplankton concentration, and in some cases, compensate for the effect of rising temperature. Copyright © 2016 Elsevier B.V. All rights reserved.

Genomic prediction for winter survival in lowland switchgrass

USDA-ARS?s Scientific Manuscript database

Switchgrass (Panicum virgatum L.) is a North American native perennial warm season grass and a promising cellulosic bioenergy feedstock. It has two ecotypes – lowland and upland. The lowland ecotype has generated considerable interest because of its higher biomass compared to the upland ecotype. How...

Titanium in UK rural, agricultural and urban/industrial rivers: geogenic and anthropogenic colloidal/sub-colloidal sources and the significance of within-river retention.

PubMed

Neal, Colin; Jarvie, Helen; Rowland, Philip; Lawler, Alan; Sleep, Darren; Scholefield, Paul

2011-04-15

Operationally defined dissolved Titanium [Ti] (the <0.45μm filtered fraction) in rivers draining rural, agricultural, urban and industrial land-use types in the UK averaged 2.1μg/l with a range in average of 0.55 to 6.48μg/l. The lowest averages occurred for the upland areas of mid-Wales the highest just downstream of major sewage treatment works (STWs). [Ti] in rainfall and cloud water in mid-Wales averaged 0.2 and 0.7μg/l, respectively. Average, baseflow and stormflow [Ti] were compared with two markers of sewage effluent and thus human population: soluble reactive phosphorus (SRP) and boron (B). While B reflects chemically conservative mixing, SRP declined downstream of STW inputs due to in-stream physico-chemical and biological uptake. The results are related to colloidal and sub-colloidal Ti inputs from urban/industrial conurbations coupled with diffuse background (geological) sources and within-river removal/retention under low flows as a result of processes of aggregation and sedimentation. The urban/industrial inputs increased background [Ti] by up to eleven fold, but the total anthropogenic Ti input might well have been underestimated owing to within-river retention. A baseline survey using cross-flow ultrafiltration revealed that up to 79% of the [Ti] was colloidal/nanoparticulate (>1kDa i.e. >c. 1-2nm) for the rural areas, but as low as 28% for the urban/industrial rivers. This raises fundamental issues of the pollutant inputs of Ti, with the possibility of significant complexation of Ti in the sewage effluents and subsequent breakdown within the rivers, as well as the physical dispersion of fine colloids down to the macro-molecular scale. Although not directly measured, the particulate Ti can make an important contribution to the net Ti flux. Copyright © 2010 Elsevier B.V. All rights reserved.

Hyporheic flow patterns in relation to large river floodplain attributes Journal

EPA Science Inventory

Field-calibrated models of hyporheic flow have emphasized low-order headwater systems. In many cases, however, hyporheic flow in large lowland river floodplains may be an important contributor to ecosystem services such as maintenance of water quality and habitat. In this study, ...

DENTAL LESIONS IN THE LOWLAND TAPIR (TAPIRUS TERRESTRIS).

PubMed

Tjørnelund, Karen B; Jonsson, Lena M; Kortegaard, Hanne; Arnbjerg, Jens; Nielsen, Søren S; Bertelsen, Mads F

2015-06-01

Dental ailments, mandibular swelling, and dentoalveolar abscesses are common in tapirs, but knowledge about prevalence or etiology of these lesions in the Tapiridae family in general, and in lowland tapirs (Tapirus terrestris) in particular, is scarce. A recent study identified resorptive lesions of unknown etiology as a common problem in the Malayan tapir (Tapirus indicus). In order to investigate the type and prevalence of dental lesions occurring in lowland tapirs, and to compare these with findings with the Malayan tapir, skulls and teeth from 46 deceased lowland tapirs were visually and radiographically examined. The specimens were divided into subpopulations according to age (juveniles, young adults, adults) and origin (free-range or captive). Dental lesions were identified in 24% (11/46) of the study population. The most common pathologic findings were complicated dental fractures with associated periapical reaction (15%) and periapical reactions of various degrees without associated detectable dental pathology (13%). All these lesions likely originated from dental trauma. As in Malayan tapirs, juveniles had significantly fewer lesions than adults. This study shows that dental lesions present frequent problems for lowland tapirs, occurring both in captive and in free-ranging individuals, and indicates that increasing age should be considered a risk factor for the development of these lesions. Notably, the predominant dental problems in lowland tapirs and Malayan tapirs are not the same.

Hydromorphological assessment and catchment characterisation in the headwaters of the Volga River

NASA Astrophysics Data System (ADS)

Marquez, Fabian; Kuzovlev, Vyacheslav. V.; Schletterer, Martin

2017-04-01

Keywords: hydromorphological assessment, lowland river, reference conditions. The Volga River and its watershed represent the largest river system in Europe. The river is considered as the Russian lifeline, and various anthropogenic activities influenced the river. Nevertheless, its headwaters remained in least disturbed conditions. We present an assessment as well as an evaluation of hydromorphological conditions in the headwaters of the Volga River regarding (1) channel, (2) banks/riparian zone and (3) floodplain. The assessment follows European standards (CEN 2004) and also includes the Habitat Quality Survey (HQA). Historical flows from five gauging stations along the studied reach were analysed to determine the hydrological characteristics. The highest flows are observed during March and April, followed by summer low flows, higher flows during October and November and low flows again during winter. A decreasing tendency of the mean annual discharge is noted throughout the observation time as it accentuates in the downstream direction when comparing the stations. Based on the specific discharge (volume of water per unit time per unit area) from these gauging stations , a flow reconstruction for the Tudovka River was carried out. These analyses contribute to the REFCOND_VOLGA project, a long-term ecological monitoring programme in the headwaters of the Volga River. The research area is characterised by large forests and low population densities, thus the results provide data about reference or least impacted sites. Due to the hydromorphological characteristics the headwaters of the Volga River, i.e. the free-flowing section between the Upper Volga Lakes and Tver represents an intact lowland river and comprises a refugial system for potamalic flora and fauna.

Modeling and assessing nitrogen delivery in the Calapooia River Watershed, and the impact of small streams delivery on downstream watershed

EPA Science Inventory

The Calapooia River is a major tributary to the Willamette River in western Oregon, which is characterized by a mountainous forested upland and a flat agricultural lowland. Here we report on a modeling study of watershed’s N budget, and quantify the influence of different...

Development and validation of a runoff and erosion model for lowland drained catchments

NASA Astrophysics Data System (ADS)

Grangeon, Thomas; Cerdan, Olivier; Vandromme, Rosalie; Landemaine, Valentin; Manière, Louis; Salvador-Blanes, Sébastien; Foucher, Anthony; Evrard, Olivier

2017-04-01

Modelling water and sediment transfer in lowland catchments is complex as both hortonian and saturation excess-flow occur in these environments. Moreover, their dynamics was complexified by the installation of tile drainage networks or stream redesign. To the best of our knowledge, few models are able to simulate saturation runoff as well as hortonian runoff in tile-drained catchments. Most of the time, they are used for small scale applications due to their high degree of complexity. In this context, a model of intermediate complexity was developed to simulate the hydrological and erosion processes at the catchment scale in lowland environments. This GIS-based, spatially distributed and lumped model at the event scale uses a theoretical hydrograph to approximate within-event temporal variations. It comprises two layers used to represent surface and subsurface transfers. Observations of soil surface characteristics (i.e. vegetation density, soil crusting and roughness) were used to document spatial variations of physical soil characteristics (e.g. infiltration capacity). Flow was routed depending on the local slope, using LIDAR elevation data. Both the diffuse and the gully erosion are explicitly described. The model ability to simulate water and sediment dynamics at the catchment scale was evaluated using the monitoring of a selection of flood events in a small, extensively cultivated catchment (the Louroux catchment, Loire River basin, central France; 25 km2). In this catchment, five monitoring stations were equipped with water level sensors, turbidity probes, and automatic samplers. Discharge and suspended sediment concentration were deduced from field measurements. One station was installed at the outlet of a tile drain and was used to parameterize fluxes supplied by the drainage network. The selected floods were representative of various rainfall and soil surface conditions (e.g. low-intensity rainfall occurring on saturated soils as well as intense rainfall

Drought, agricultural adaptation, and sociopolitical collapse in the Maya Lowlands

PubMed Central

Douglas, Peter M. J.; Pagani, Mark; Canuto, Marcello A.; Brenner, Mark; Hodell, David A.; Eglinton, Timothy I.; Curtis, Jason H.

2015-01-01

Paleoclimate records indicate a series of severe droughts was associated with societal collapse of the Classic Maya during the Terminal Classic period (∼800–950 C.E.). Evidence for drought largely derives from the drier, less populated northern Maya Lowlands but does not explain more pronounced and earlier societal disruption in the relatively humid southern Maya Lowlands. Here we apply hydrogen and carbon isotope compositions of plant wax lipids in two lake sediment cores to assess changes in water availability and land use in both the northern and southern Maya lowlands. We show that relatively more intense drying occurred in the southern lowlands than in the northern lowlands during the Terminal Classic period, consistent with earlier and more persistent societal decline in the south. Our results also indicate a period of substantial drying in the southern Maya Lowlands from ∼200 C.E. to 500 C.E., during the Terminal Preclassic and Early Classic periods. Plant wax carbon isotope records indicate a decline in C4 plants in both lake catchments during the Early Classic period, interpreted to reflect a shift from extensive agriculture to intensive, water-conservative maize cultivation that was motivated by a drying climate. Our results imply that agricultural adaptations developed in response to earlier droughts were initially successful, but failed under the more severe droughts of the Terminal Classic period. PMID:25902508

RED SHINER INVASION OF THE UPPER COOSA RIVER SYSTEM: DYNAMICS AND ECOLOGICAL CONSEQUENCES

EPA Science Inventory

The red shiner (Cyprinella lutrensis) has been widely introduced across 11 states outside its native range, presumably through bait-bucket and aquarium releases. Its native range includes Great Plain and Central Lowland tributaries of the Mississippi River and western Coastal Pla...

Mars, highlands-lowlands: Viking contributions to mariner relative age studies

USGS Publications Warehouse

Scott, D.H.

1978-01-01

Stratigraphic relations between lowland plains and highlands, two major types of Martian geologic-terrain units, were not directly distinguishable on Mariner-9 images. Morphologic characteristics and crater densities suggested that the lava plains beneath their eolian cover were younger than adjacent highland rocks, which form a plateau bounded in many places by highly dissected escarpments. Alternatively, the lowland plains could be the older unit and represent a broad erosional surface exhumed by southward retreat of the highlands along their frontal scarp. Viking photos across five areas of the highland-lowland boundary, however, tend to confirm the younger age of the plains-forming lava flows. A time interval of several hundred million years probably occurred between the retreat of the highland scarp and its latest embayment by lava extrusions in the lowlands. ?? 1978.

Nitrogen budget in a lowland coastal area within the Po River basin (northern Italy): multiple evidences of equilibrium between sources and internal sinks.

PubMed

Castaldelli, Giuseppe; Soana, Elisa; Racchetti, Erica; Pierobon, Enrica; Mastrocicco, Micol; Tesini, Enrico; Fano, Elisa Anna; Bartoli, Marco

2013-09-01

Detailed studies on pollutants genesis, path and transformation are needed in agricultural catchments facing coastal areas. Here, loss of nutrients should be minimized in order to protect valuable aquatic ecosystems from eutrophication phenomena. A soil system N budget was calculated for a lowland coastal area, the Po di Volano basin (Po River Delta, Northern Italy), characterized by extremely flat topography and fine soil texture and bordering a network of lagoon ecosystems. Main features of this area are the scarce relevance of livestock farming, the intense agriculture, mainly sustained by chemical fertilizers, and the developed network of artificial canals with long water residence time. Average nitrogen input exceeds output terms by ~60 kg N ha(-1) year(-1), a relatively small amount if compared to sub-basins of the same hydrological system. Analysis of dissolved inorganic nitrogen in groundwater suggests limited vertical loss and no accumulation of this element, while a nitrogen mass balance in surface waters indicates a net and significant removal within the watershed. Our data provide multiple evidences of efficient control of the nitrogen excess in this geographical area and we speculate that denitrification in soil and in the secondary drainage system performs this ecosystemic function. Additionally, the significant difference between nitrogen input and nitrogen output loads associated to the irrigation system, which is fed by the N-rich Po River, suggests that this basin metabolizes part of the nitrogen excess produced upstream. The traditionally absent livestock farming practices and consequent low use of manure as fertilizer pose the risk of excess soil mineralization and progressive loss of denitrification capacity in this area.

Peat landforms along the Albany River, northern Ontario. An ecological study of peat landforms in Canada and Alaska

NASA Technical Reports Server (NTRS)

Glaser, P. H.

1985-01-01

During the summer of 1985 a field investigation was started in the Hudson Bay lowland region of northern Ontario, which represents the largest expanse of peatland in North America and is an important sink in the global carbon cycle. A key area in the lowlands is situated along the Albany River near the confluence of the Chepay River. Here the striking vegetation-landforms are transitional between those found on the bed of Glacial Lake Agassiz in northern Minnesota and southern Manitoba and the more northern peatlands in the Hudson Bay lowland region. In peatland studies elsewhere the landform patterns have been used not only to classify different peatland types but also as an indicator of potential developmetnal trends. The study area is generally defined by that covered by the TM scene E-40062-15532 taken on Sept. 16, 1982. The purpose of the field work is to acquire sufficent information to interpret the TM imagery and test various hypotheses on peatland development on the gasis of the pattern transitions.

Patterns of Ground Water Movement in a Portion of the Willamette River Floodplain, Oregon

EPA Science Inventory

In reaches unconstrained by revetments, the Willamette River and its floodplain along its lowland mainstem is a continually evolving system. Several channel reconstruction and restoration projects have been implemented or planned in order to obtain beneficial services along the r...

Hydroecological monitoring in the headwaters of the Volga River

NASA Astrophysics Data System (ADS)

Kuzovlev, Viacheslav V.; Zhenikov, Yuri N.; Zhenikov, Kyrill Y.; Shaporenko, Sergey I.; Haun, Stefan; Füreder, Leopold; Schletterer, Martin

2016-04-01

Europe's largest river, the Volga (3551 km), has experienced multiple stressors from human activities (i.e. the Volga Basin comprises about 40 % of the Russian population, 45 % of the country's industry and more than 50 % of its agriculture). During the research expedition "Upper Volga 2005" an assessment of hydrological, limnochemical and biological parameters was carried out by scientists from the Russian Federation and from Austria. The extensive sampling in 2005 showed that the free-flowing section of the Volga River, located upstream of Tver, represents conditions which are either reference or least disturbed - thus it can be considered as a refugial system for freshwater biota of the European lowlands. Subsequently three stretches in the headwaters of the Volga River (Rzhev, Staritsa, Tver) were selected for the monitoring programme "REFCOND_VOLGA", which is in operation since 2006. These locations correspond also with the sampling sites of ROSHYDROMET, i.e. at Tver physic-chemical samples are taken monthly and at Rzhev samples are taken in the main hydrological periods. The laboratory ship "ROSHYDROMET 11" conducted monthly cruises between Tver and Kalyazin (Ivankovskoye and Uglichskoye reservoirs on Volga) in the headwaters during the navigation period (May - October). This also includes measurements with ADCP, which further allow the analyses of the spatial distribution of the suspended solids within cross sections. In addition sediment fluxes were derived by using the acoustic backscatter signal strength from the acoustic current Doppler profiler (ADCP). We exemplify at the monitoring sites the spatial distribution of different sediments, i.e. choriotope types, according the longitudinal profile of the river. We show that it is highly influenced by morphodynamics in the different river sections and this corresponds with the zoobenthos fauna accordingly. This interdisciplinary approach, including sediment conditions, limnochemistry, hydrology and

The science and practice of river restoration

NASA Astrophysics Data System (ADS)

Wohl, Ellen; Lane, Stuart N.; Wilcox, Andrew C.

2015-08-01

River restoration is one of the most prominent areas of applied water-resources science. From an initial focus on enhancing fish habitat or river appearance, primarily through structural modification of channel form, restoration has expanded to incorporate a wide variety of management activities designed to enhance river process and form. Restoration is conducted on headwater streams, large lowland rivers, and entire river networks in urban, agricultural, and less intensively human-altered environments. We critically examine how contemporary practitioners approach river restoration and challenges for implementing restoration, which include clearly identified objectives, holistic understanding of rivers as ecosystems, and the role of restoration as a social process. We also examine challenges for scientific understanding in river restoration. These include: how physical complexity supports biogeochemical function, stream metabolism, and stream ecosystem productivity; characterizing response curves of different river components; understanding sediment dynamics; and increasing appreciation of the importance of incorporating climate change considerations and resiliency into restoration planning. Finally, we examine changes in river restoration within the past decade, such as increasing use of stream mitigation banking; development of new tools and technologies; different types of process-based restoration; growing recognition of the importance of biological-physical feedbacks in rivers; increasing expectations of water quality improvements from restoration; and more effective communication between practitioners and river scientists.

Estimating the recreational carrying capacity of a lowland river section.

PubMed

Lorenz, Stefan; Pusch, Martin T

2012-01-01

Recreational boating represents a major human use of inland waters in many regions. However, boating tourism may affect the ecological integrity of surface waters in multiple ways. In particular, surface waves produced by boating may disturb freshwater invertebrates, such as interrupting the filtration activity of benthic mussels. As mussels may significantly contribute to self-purification, disturbance may have crucial impacts on water quality, and thus on water tourism. In this paper we calculate the carrying capacity of a river section for sustainable boating tourism based on the preservation of water quality. This approach is complemented by spatial and social approaches for carrying capacity estimates. The ecological carrying capacity significantly decreases with lower water levels during summer. Hence, the analysis of variables that influence the river's carrying capacity allows the formation of recommendations for management measures that integrate social, touristic and ecological aspects.

The Role of Conjoining (Tie) Channels in Lowland Floodplain Development and Lake Infilling

NASA Astrophysics Data System (ADS)

Rowland, J. C.; Dietrich, W. E.; Day, G.; Lepper, K.; Wilson, C. J.

2003-12-01

In simple models of lowland river systems, water and sediment enter the main stem via tributary and secondary channels and are only redistributed to the floodplain during overbank and crevasse splay events. Along numerous river systems across the globe, however, water and sediment are regularly exchanged between the river and off river water bodies via stable, narrow channels. These channels, known as tie channels on the Fly River in Papua New Guinea and batture channels along the lower Mississippi, are largely overlooked but important components of floodplain sediment dispersal where they exist. These channels become pathways of sediment dispersal to the floodplain system when elevated river stages force sediment-laden flows into the off-river water bodies. On the Fly River, it is estimated that about 50% of the sediment delivery to the floodplain is via these channels, and along low gradient tributary channels during flood driven flow reversals. During low flow, tie channels serve to drain the floodplain. With the outgoing flows, large amounts sediment can be carried and lost to the floodplain; floodplain lakes progressively infill with sediment as the mouth of these channels steadily prograde lakeward. These lake deposits not only become significant stratigraphic components of floodplains (traditionally referred to as clay plugs), but are important local sinks recording hundreds to thousands of years of river history. As with all sinks, the proper interpretation of these stratigraphic records requires understanding the processes by which sediment is delivered to the sink and how these processes alter the paleohydraulic and climatic signals of interest. We have conducted field investigations of conjoining channels in Papua New Guinea (the Fly and Strickland Rivers), Louisiana (Raccourci Old River ~ 65 km upriver of Baton Rouge) and Alaska (Birch Creek). These field investigations include extensive surveys of both cross and along channel morphological trends

Dimensions of the foot muscles in the lowland gorilla.

PubMed

Oishi, Motoharu; Ogihara, Naomichi; Endo, Hideki; Komiya, Teruyuki; Kawada, Shin-Ichiro; Tomiyama, Tae; Sugiura, Yosuke; Ichihara, Nobutsune; Asari, Masao

2009-06-01

We dissected the hindlimb of a female western lowland gorilla and determined the muscle dimensions (mass, fascicle length, and physiological cross-sectional area: PCSA). Comparisons of the muscle parameters of the measured gorilla with corresponding reported human data demonstrated that the triceps surae muscles were larger and had more capacity to generate force than the other muscle groups in both species, but this tendency was more prominent in the human, probably as an adaptation to strong toe-off during bipedal walking. On the other hand, PCSAs of the extrinsic pedal digital flexors and digiti minimi muscles were larger in the western lowland gorilla, suggesting that the foot, particularly the fifth toe, has a relatively high grasping capability in the lowland gorilla.

Ongoing River Capture in the Amazon via Secondary Channel Flow

NASA Astrophysics Data System (ADS)

Goldberg, S. L.; Stokes, M.; Perron, J. T.

2017-12-01

The Rio Casiquiare in South America is a secondary channel that originates as a distributary of the Rio Orinoco and flows into the Rio Negro as a tributary to form a perennial connection between the Amazon and Orinoco basins, the largest and fourth-largest rivers on Earth by discharge. This unusual configuration is the result of an incomplete and ongoing river capture in which the Rio Negro is actively capturing the upper Rio Orinoco. This rarely observed intermediate stage of capture illuminates important mechanisms that drive river capture in lowland settings, both in the Amazon basin and elsewhere. In particular, we show that the capture of the Rio Orinoco by the Rio Casiquiare is driven by a combination of headward incision of a rapidly eroding tributary of the Rio Negro, sedimentation in the Rio Orinoco downstream of the bifurcation, and seasonal inundation of a low-relief divide. The initiation of the bifurcation by headward erosion caused an increase in discharge to the Rio Casiquiare while the corresponding loss of discharge to the downstream Rio Orinoco has led to observable sedimentation within the main channel. Unlike most ephemeral secondary channels, the Rio Casiquiare appears to be growing, suggesting that the present bifurcation is an unstable feature that will eventually lead to the complete capture of the upper Rio Orinoco by the Rio Casiquiare. This capture is the latest major event in the late Cenozoic drainage evolution of South America in response to Andean tectonism, and is an example of the lateral expansion of the Amazon basin through river capture following integration and entrenchment of the transcontinental Amazon River. The Rio Casiquiare provides a snapshot of an intermediate, transient state of bifurcation and inter-basin flow via a secondary channel during lowland river capture.

Water resources in the Blackstone River basin, Massachusetts

USGS Publications Warehouse

Walker, Eugene H.; Krejmas, Bruce E.

1983-01-01

The Blackstone River heads in brooks 6 miles northwest of Worcester and drains about 330 square miles of central Massachusetts before crossing into Rhode Island at Woonsocket. The primary source of the Worcester water supply is reservoirs, but for the remaining 23 communities in the basin, the primary source is wells. Bedrock consists of granitic and metamorphic rocks. Till mantles the uplands and extends beneath stratified drift in the valleys. Stratified glacial drift, consisting of clay, silt, and fine sand deposited in lakes and coarse-textured sand and gravel deposited by streams, is found in lowlands and valleys. The bedrock aquifer is capable of sustaining rural domestic supplies throughout the Blackstone River basin. Bedrock wells yield an average of 10 gallons per minute, but some wells, especially those in lowlands where bedrock probably contains more fractures and receives more recharge than in the upland areas, yield as much as 100 gallons per minute. Glacial sand and gravel is the principal aquifer. It is capable of sustaining municipal supplies. Average daily pumpage from this aquifer in the Blackstone River basin was 10.4 million gallons per day in 1978. The median yield of large-diameter wells in the aquifer is 325 gallons per minute. The range of yields from these wells is 45 to 3,300 gallons per minute. The median specific capacity is about 30 gallons per minute per foot of drawdown.

Quaternary Morphodynamics of Fluvial Dispersal Systems Revealed: The Fly River, PNG, and the Sunda Shelf, SE Asia, simulated with the Massively Parallel GPU-based Model 'GULLEM'

NASA Astrophysics Data System (ADS)

Aalto, R. E.; Lauer, J. W.; Darby, S. E.; Best, J.; Dietrich, W. E.

2015-12-01

During glacial-marine transgressions vast volumes of sediment are deposited due to the infilling of lowland fluvial systems and shallow shelves, material that is removed during ensuing regressions. Modelling these processes would illuminate system morphodynamics, fluxes, and 'complexity' in response to base level change, yet such problems are computationally formidable. Environmental systems are characterized by strong interconnectivity, yet traditional supercomputers have slow inter-node communication -- whereas rapidly advancing Graphics Processing Unit (GPU) technology offers vastly higher (>100x) bandwidths. GULLEM (GpU-accelerated Lowland Landscape Evolution Model) employs massively parallel code to simulate coupled fluvial-landscape evolution for complex lowland river systems over large temporal and spatial scales. GULLEM models the accommodation space carved/infilled by representing a range of geomorphic processes, including: river & tributary incision within a multi-directional flow regime, non-linear diffusion, glacial-isostatic flexure, hydraulic geometry, tectonic deformation, sediment production, transport & deposition, and full 3D tracking of all resulting stratigraphy. Model results concur with the Holocene dynamics of the Fly River, PNG -- as documented with dated cores, sonar imaging of floodbasin stratigraphy, and the observations of topographic remnants from LGM conditions. Other supporting research was conducted along the Mekong River, the largest fluvial system of the Sunda Shelf. These and other field data provide tantalizing empirical glimpses into the lowland landscapes of large rivers during glacial-interglacial transitions, observations that can be explored with this powerful numerical model. GULLEM affords estimates for the timing and flux budgets within the Fly and Sunda Systems, illustrating complex internal system responses to the external forcing of sea level and climate. Furthermore, GULLEM can be applied to most ANY fluvial system to

Hot Moments in Cold Spots - Investigating Reactive Transport Patterns at Aquifer-River Interfaces by Heat Tracers and Distributed Sensor Networks

NASA Astrophysics Data System (ADS)

Krause, Stefan; Angermann, Lisa; Naden, Emma; Cassidy, Nigel; Blume, Theresa

2010-05-01

The mixing of groundwater and surface water in hyporheic zones often coincides with high redox reactivity and chemical transformation potential. Depending on redox conditions and reaction types, hyporheic mixing of groundwater and surface water can lead to either attenuation or enrichment of pollutants or nutrients with diametrical implications for stream and aquifer hydro-ecological conditions. This study investigates the reactive transport of nitrate and a chlorinated solvent (Trichloroethylene - TCE) at the aquifer-river interface of a UK lowland river. In this study, distributed temperature sensor networks and hydro-geophysical methods, which have been applied for identifying structural streambed heterogeneity and tracing aquifer river exchange, were combined with hydro-chemical analyses of hyporheic multi-component reactive transport. In stream Electric Resistivity Tomography has been applied to map the complex spatial distribution of highly conductive sandy and gravely sediments in contrast to semi-confining, low conductivity peat lenses. Reach scale (1km) spatial patterns and temporal dynamics of aquifer-river exchange have been identified by heat tracer experiments based on fibre-optic Distributed Temperature Sensing in combination with 2D thermocouple-arrays and small scale heat pulse injection methods for tracing shallow (25 cm) hyporheic flow paths. Spatial patterns of hyporheic redox conditions, dissolved oxygen and organic carbon (DOC) content as well as concentrations of major anions, TCE and its decay products have been observed in 48 nested multi-level piezometers and passive DET (Diffusive Equilibrium in Thin film) gel probes. Our results indicate that patterns of cold spots in streambed sediments can be attributed to fast groundwater up-welling in sandy and gravely sediments resulting in low hyporheic residence times. Contrasting conditions were found at warmer areas at the streambed surface where groundwater - surface water exchange was inhibited

Erosion of particulate organic material from an Andean river and its delivery to the Amazon Basin

NASA Astrophysics Data System (ADS)

Clark, Kathryn; Hilton, Robert; West, A. Joshua; Robles Caceres, Arturo; Grocke, Darren; Marthews, Toby; Asner, Greg; New, Mark; Mahli, Yadvinder

2016-04-01

Organic carbon and nutrients discharged by mountainous rivers can play an important role in biogeochemical cycles from regional to global scales. The eastern Andes host productive forests on steep, rapidly eroding slopes, a combination that is primed to deliver sediment, carbon and nutrients to the lowland Amazon River. We quantify clastic sediment and particulate organic carbon (POC) discharge for the Kosñipata River, Peru, an Andean tributary of the Madre de Dios River, using suspended sediment samples and discharge measurements over one year at two gauging stations. Calculations of sediment yield on the basis of this data suggest that the Madre de Dios basin may have erosion rates ˜10 times greater than the Amazon Basin average. The total POC yield over the sampling period was up to five times higher than the yield in the lowland Amazon Basin, with most POC (70-80%) exported between December and March in the wet season. We use radiocarbon, stable C isotopes and C/N ratios to distinguish between the erosion and discharge of POC from sedimentary rocks (petrogenic POC) and POC eroded from the modern terrestrial biosphere, from vegetation and soil (biospheric POC). We find that biospheric POC discharge was significantly enhanced during flood events, over that of clastic sediment and petrogenic POC. The ultimate fate of the eroded POC may play a central role in the net carbon budget of Andean forest. In these forests, net productivity minus heterotrophic respiration is close to zero at the scale of forest plots, and the erosion of biospheric POC by this Andean river is sufficiently rapid that its fate downstream (sedimentary burial/preservation versus oxidation/degradation) may determine whether the mountain forest is a carbon sink or source to the atmosphere. In addition, the measured discharge of petrogenic POC suggests that fluxes from the Andes may be considerably higher than measured downstream in the Madeira River. If this petrogenic POC is oxidised rather

Riparian valley oak (Quercus lobata) forest restoration on the middle Sacramento River, California

Treesearch

F. Thomas Griggs; Gregory H. Golet

2002-01-01

In 1989 The Nature Conservancy initiated a riparian horticultural restoration program on the floodplain of the middle Sacramento River, California. At nearly all restoration sites Valley oak (Quercus lobata Nee) comprised a major component of the planting design. Valley oaks are a keystone tree species of lowland floodplain habitats in California...

Downstream changes of water quality in a lowland river due to groundwater inflows.

NASA Astrophysics Data System (ADS)

Zieba, Damian; Bar-Michalczyk, Dominika; Kania, Jarosław; Malina, Grzegorz; Michalczyk, Tomasz; Rozanski, Kazimierz; Witczak, Stanislaw; Wachniew, Przemyslaw; Zurek, Anna J.

2016-04-01

The Kocinka catchment (ca. 250 km2) in southern Poland receives substantial inflows of groundwater from a major fissured-carbonate aquifer polluted with nitrates originating from agriculture and domestic sewage. The 40 km long Kocinka river reveals large spatial variations in physical and chemical water properties with large downstream changes of nitrate concentrations. Detailed longitudinal surveys of such water characteristics as nitrate concentration, water temperature, pH, electric conductivity, stable isotopic composition, tritium concentration were performed in order to identify and quantify groundwater inflows. The river gains groundwater down to the 25 km from the source and a looses water further downstream. The subsequent increase and decrease of nitrate concentration in the upper and middle reaches of the river are caused by inflows of the, respectively, polluted and non-polluted groundwaters. The range of such changes can be even five-fold while the drop of nitrate concentration along the semi natural, 18 km long, lower reach where the river is well connected to its riparian and hyporheic zones nitrate loss is of the order of 10%. More significant nitrate losses were observed in the dammed reaches and in a small reservoir in the upper part of the river. Results of the study have implications for identification of measures that can be undertaken to reduce nitrate export from the catchment. Because of the role of groundwater in river runoff reduction of nitrate loads to the aquifer should be primary objective. Acknowledgements. The work was carried out as part of the BONUS Soils2Sea project on groundwater system (http:/www.soils2sea.eu) financed by the European Commission 7 FP contract 226536 and the statutory funds of the AGH University of Science and Technology (project No.11.11.140.026 and 11.11.220.01).

Hot Moments in Cold Spots - Using Heat Tracers and Distributed Sensor Networks to Investigate Reactive Transport Patterns at Aquifer-River Interfaces

NASA Astrophysics Data System (ADS)

Krause, S.; Angermann, L.; Naden, E.; Cassidy, N. J.

2009-12-01

The mixing of groundwater and surface water in hyporheic zones often coincides high redox reactivity and chemical transformation potential. Depending on redox conditions and reaction types, hyporheic mixing of groundwater and surface water can lead to either attenuation or enrichment of pollutants or nutrients with diametrical implications for stream and aquifer hydro-ecology. This study investigates the reactive transport of nitrate and the chlorinated solvent Trichloroethylene (TCE) at the aquifer-river interface of a UK lowland river. The investigations are based on novel distributed sensor networks and hydro-geophysical methods for the identification of structural streambed heterogeneity and the tracing of aquifer river exchange combined with hydro-chemical analyses of hyporheic multi-component reactive transport. In stream Electric Resistivity Tomography and Ground Penetrating Radar have been applied to map the complex spatial distribution of highly conductive sandy and gravely sediments in contrast to semi-confining, low conductivity peat lenses. Reach scale (1km) spatial patterns and temporal dynamics of aquifer-river exchange have been identified by heat tracer experiments based on fibre-optic Distributed Temperature Sensing in combination with 2D thermocouple-arrays and small scale heat pulse injection methods for tracing shallow (25 cm) hyporheic flow paths. Spatial patterns of hyporheic redox conditions, dissolved oxygen and organic carbon (DOC) content as well as concentrations of major anions, TCE and its decay products have been observed in 48 nested multi-level piezometers and passive DET (Diffusive Equilibrium in Thin film) gel probes. Our results indicate that patterns of cold spots in streambed sediments can be attributed to fast groundwater up-welling in sandy and gravely sediments resulting in low hyporheic residence times. Contrasting conditions were found at warmer areas at the streambed surface where groundwater - surface water exchange was

A spatial and seasonal assessment of river water chemistry across North West England.

PubMed

Rothwell, J J; Dise, N B; Taylor, K G; Allott, T E H; Scholefield, P; Davies, H; Neal, C

2010-01-15

This paper presents information on the spatial and seasonal patterns of river water chemistry at approximately 800 sites in North West England based on data from the Environment Agency regional monitoring programme. Within a GIS framework, the linkages between average water chemistry (pH, sulphate, base cations, nutrients and metals) catchment characteristics (topography, land cover, soil hydrology, base flow index and geology), rainfall, deposition chemistry and geo-spatial information on discharge consents (point sources) are examined. Water quality maps reveal that there is a clear distinction between the uplands and lowlands. Upland waters are acidic and have low concentrations of base cations, explained by background geological sources and land cover. Localised high concentrations of metals occur in areas of the Cumbrian Fells which are subjected to mining effluent inputs. Nutrient concentrations are low in the uplands with the exception sites receiving effluent inputs from rural point sources. In the lowlands, both past and present human activities have a major impact on river water chemistry, especially in the urban and industrial heartlands of Greater Manchester, south Lancashire and Merseyside. Over 40% of the sites have average orthophosphate concentrations >0.1mg-Pl(-1). Results suggest that the dominant control on orthophosphate concentrations is point source contributions from sewage effluent inputs. Diffuse agricultural sources are also important, although this influence is masked by the impact of point sources. Average nitrate concentrations are linked to the coverage of arable land, although sewage effluent inputs have a significant effect on nitrate concentrations. Metal concentrations in the lowlands are linked to diffuse and point sources. The study demonstrates that point sources, as well as diffuse sources, need to be considered when targeting measures for the effective reduction in river nutrient concentrations. This issue is clearly important

Postcolonial Hybrids in "The Lowland"

ERIC Educational Resources Information Center

Ghoreishi, Seyedeh Zahra; Bordbari, Zahra

2016-01-01

This paper delves into Jhumpa Lahiri's 2013 novel, "The Lowland", to analyze the diasporic experience of the Indianborn characters. Homi Bhabha's postcolonial approach is utilized to demonstrate the ways in which the characters perceive the immigration experience, and to unravel the causes of their despair, the disintegration of their…

Impacts of climate change on in-stream nitrogen in a lowland chalk stream: an appraisal of adaptation strategies.

PubMed

Whitehead, P G; Wilby, R L; Butterfield, D; Wade, A J

2006-07-15

The impacts of climate change on nitrogen (N) in a lowland chalk stream are investigated using a dynamic modelling approach. The INCA-N model is used to simulate transient daily hydrology and water quality in the River Kennet using temperature and precipitation scenarios downscaled from the General Circulation Model (GCM) output for the period 1961-2100. The three GCMs (CGCM2, CSIRO and HadCM3) yield very different river flow regimes with the latter projecting significant periods of drought in the second half of the 21st century. Stream-water N concentrations increase over time as higher temperatures enhance N release from the soil, and lower river flows reduce the dilution capacity of the river. Particular problems are shown to occur following severe droughts when N mineralization is high and the subsequent breaking of the drought releases high nitrate loads into the river system. Possible strategies for reducing climate-driven N loads are explored using INCA-N. The measures include land use change or fertiliser reduction, reduction in atmospheric nitrate and ammonium deposition, and the introduction of water meadows or connected wetlands adjacent to the river. The most effective strategy is to change land use or reduce fertiliser use, followed by water meadow creation, and atmospheric pollution controls. Finally, a combined approach involving all three strategies is investigated and shown to reduce in-stream nitrate concentrations to those pre-1950s even under climate change.

Attenuation of organic micropollutants in an urban lowland stream under varying seasonal and hydrological conditions

NASA Astrophysics Data System (ADS)

Jaeger, Anna; Posselt, Malte; Schaper, Jonas; Lewandowski, Jörg

2017-04-01

Transport and fate of polar organic micropollutants in urban streams are of increasing concern for urban water management. Appropriate river management techniques may support a river's ability to self-purify. The river Erpe, an urban lowland stream located in Berlin, Germany, receives treated wastewater which increases its discharge up to 4-fold. Numerous micropollutants (e.g. pharmaceuticals, personal care products, performance chemicals) which survive the treatment process are released into the river and threaten ecosystems and aquatic groundwater quality. In the present work the transport of 57 substances was investigated along a 4.7 km stretch of the river with the aim of understanding the influence of varying seasonal and hydrological conditions on micropollutant fate. We hypothesized that particularly transient storage is a main driver of micropollutant attenuation. A Lagrangian sampling scheme was applied to follow water parcels down the river using the diurnal fluctuations of conservative solute concentrations as an intrinsic tracer. Water samples were collected at two (April) and three (June) stations along a 4.7 km reach downstream of the wastewater inflow. In June the experiment was conducted twice, before and after the first stretch was cleared of macrophytes. Each experiment comprised of hourly sample collection for 48 hours, accompanied by discharge measurements and continuous data logging of water-level, -temperature and electric conductivity. The set of micropollutants, which included both parent compounds and transformation products, was analysed by a newly developed direct injection-UHPLC-MS/MS method. The behaviour of individual micropollutants was compound-specific. Carbamazepine and benzotriazole were persistent along the river stretch while substances such as valsartan and metoprolol were attenuated by up to 15% of their original concentration. Interestingly, some transformation products, such as valsartan acid increased in concentration

River logjams cause frequent large-scale forest die-off events in southwestern Amazonia

NASA Astrophysics Data System (ADS)

Lombardo, Umberto

2017-07-01

This paper investigates the dynamics of logjam-induced floods and alluvial deposition in the Bolivian Amazon and the effects these have on forest disturbance and recovery cycles. It expands on previous work by Gullison et al. (1996) who reported a case of catastrophic floods triggered by logjams in the Chimane Forest in the Bolivian Amazon. No further studies have followed up on this observation and no research has been published on the effects of large wood in tropical lowland rivers. The study is based on the analysis of a time series of Landsat imagery (1984-2016) and field evidence. Results show that logjam-induced floods are a major driver of forest disturbance along the Andean piedmont in the Bolivian Amazon. New logjams form on an almost yearly basis, always further upriver, until an avulsion takes place. Logjam-induced floods are characterized here by the sudden deposition of a thick sand layer and the death of forest in a V-shaped area. The Bolivian Amazon offers a unique opportunity for further research on how large wood affects river behavior in lowland tropical settings and how large and frequent forest disturbance events resulting from river logjams affect forest biodiversity and community successions.

Sediment size of surface floodplain sediments along a large lowland river

NASA Astrophysics Data System (ADS)

Swanson, K. M.; Day, G.; Dietrich, W. E.

2007-12-01

Data on size distribution of surface sediment across a floodplain should place important constraints of modeling of floodplain deposition. Diffusive or advective models would predict that, generally, grain size should decrease away from channel banks. Variations in grain size downstream along floodplains may depend on downstream fining of river bed material, exchange rate with river banks and net deposition onto the floodplain. Here we report detailed grain size analyses taken from 17 floodplain transects along 450 km (along channel distance) reach of the middle Fly River, Papua New Guinea. Field studies have documented a systematic change in floodplain characteristics downstream from forested, more topographically elevated and topography bounded by an actively shifting mainstem channel to a downstream swamp grass, low elevation topography along which the river meanders are currently stagnant. Frequency and duration of flooding increase downstream. Flooding occurs both by overbank flows and by injections of floodwaters up tributary and tie channels connected to the mainstem. Previous studies show that about 40% of the total discharge of water passes across the floodplain, and, correspondingly, about 40% of the total load is deposited on the plain - decreasing exponentially from channel bank. We find that floodplain sediment is most sandy at the channel bank. Grain size rapidly declines away from the bank, but surprisingly two trends were also observed. A relatively short distance from the bank the surface material is finest, but with further distance from the bank (out to greater than 1 km from the 250 m wide channel) clay content decreases and silt content increases. The changes are small but repeated at most of the transects. The second trend is that bank material fines downstream, corresponding to a downstream finding bed material, but once away from the bank, there is a weak tendency for a given distance away from the bank the floodplain surface deposits to

Puget Lowland Ecoregion: Chapter 2 in Status and trends of land change in the Western United States--1973 to 2000

USGS Publications Warehouse

Sorenson, Daniel G.

2012-01-01

vegetation zone is named after the western hemlock (Tsuga heterophylla), Douglas-fir (Pseudotsuga menziesii) is the dominant tree species. Seattle, which had an estimated population of 563,376 in 2000, is the largest city in the Puget Lowland Ecoregion (Puget Sound Regional Council, 2001). The greater Seattle metropolitan area, comprising Seattle, Tacoma, Bellevue, and Bremerton, had an estimated population of 3.5 million people in 2000 (U.S. Census Bureau, 2000). Other sizable cities in the ecoregion include the state capital Olympia, as well as Tacoma, Bellingham, and Everett, Washington. The center of the Puget Lowland Ecoregion is dominated by the Seattle metropolitan area and developed land cover, whereas agriculture occurs mainly on river floodplains in the north and south. The remainder of the ecoregion area is dominated by forest land cover (fig. 1).

The mountain-lowland debate: deforestation and sediment transport in the upper Ganga catchment.

PubMed

Wasson, R J; Juyal, N; Jaiswal, M; McCulloch, M; Sarin, M M; Jain, V; Srivastava, P; Singhvi, A K

2008-07-01

The Himalaya-Gangetic Plain region is the iconic example of the debate about the impact on lowlands of upland land-use change. Some of the scientific aspects of this debate are revisited by using new techniques to examine the role of deforestation in erosion and river sediment transport. The approach is whole-of-catchment, combining a history of deforestation with a history of sediment sources from well before deforestation. It is shown that deforestation had some effect on one very large erosional event in 1970, in the Alaknanda subcatchment of the Upper Ganga catchment, but that both deforestation and its effects on erosion and sediment transport are far from uniform in the Himalaya. Large magnitude erosional events occur for purely natural reasons. The impact on the Gangetic Plain of erosion caused by natural events and land cover change remains uncertain.

Dissecting maize diversity in lowland South America: genetic structure and geographic distribution models.

PubMed

Bracco, Mariana; Cascales, Jimena; Hernández, Julián Cámara; Poggio, Lidia; Gottlieb, Alexandra M; Lia, Verónica V

2016-08-26

Maize landraces from South America have traditionally been assigned to two main categories: Andean and Tropical Lowland germplasm. However, the genetic structure and affiliations of the lowland gene pools have been difficult to assess due to limited sampling and the lack of comparative analysis. Here, we examined SSR and Adh2 sequence variation in a diverse sample of maize landraces from lowland middle South America, and performed a comprehensive integrative analysis of population structure and diversity including already published data of archaeological and extant specimens from the Americas. Geographic distribution models were used to explore the relationship between environmental factors and the observed genetic structure. Bayesian and multivariate analyses of population structure showed the existence of two previously overlooked lowland gene pools associated with Guaraní indigenous communities of middle South America. The singularity of this germplasm was also evidenced by the frequency distribution of microsatellite repeat motifs of the Adh2 locus and the distinct spatial pattern inferred from geographic distribution models. Our results challenge the prevailing view that lowland middle South America is just a contact zone between Andean and Tropical Lowland germplasm and highlight the occurrence of a unique, locally adapted gene pool. This information is relevant for the conservation and utilization of maize genetic resources, as well as for a better understanding of environment-genotype associations.

Changes in plant community composition lag behind climate warming in lowland forests.

PubMed

Bertrand, Romain; Lenoir, Jonathan; Piedallu, Christian; Riofrío-Dillon, Gabriela; de Ruffray, Patrice; Vidal, Claude; Pierrat, Jean-Claude; Gégout, Jean-Claude

2011-10-19

Climate change is driving latitudinal and altitudinal shifts in species distribution worldwide, leading to novel species assemblages. Lags between these biotic responses and contemporary climate changes have been reported for plants and animals. Theoretically, the magnitude of these lags should be greatest in lowland areas, where the velocity of climate change is expected to be much greater than that in highland areas. We compared temperature trends to temperatures reconstructed from plant assemblages (observed in 76,634 surveys) over a 44-year period in France (1965-2008). Here we report that forest plant communities had responded to 0.54 °C of the effective increase of 1.07 °C in highland areas (500-2,600 m above sea level), while they had responded to only 0.02 °C of the 1.11 °C warming trend in lowland areas. There was a larger temperature lag (by 3.1 times) between the climate and plant community composition in lowland forests than in highland forests. The explanation of such disparity lies in the following properties of lowland, as compared to highland, forests: the higher proportion of species with greater ability for local persistence as the climate warms, the reduced opportunity for short-distance escapes, and the greater habitat fragmentation. Although mountains are currently considered to be among the ecosystems most threatened by climate change (owing to mountaintop extinction), the current inertia of plant communities in lowland forests should also be noted, as it could lead to lowland biotic attrition. ©2011 Macmillan Publishers Limited. All rights reserved

MARSIS radar sounder evidence of buried basins in the northern lowlands of Mars.

PubMed

Watters, Thomas R; Leuschen, Carl J; Plaut, Jeffrey J; Picardi, Giovanni; Safaeinili, Ali; Clifford, Stephen M; Farrell, William M; Ivanov, Anton B; Phillips, Roger J; Stofan, Ellen R

2006-12-14

A hemispheric dichotomy on Mars is marked by the sharp contrast between the sparsely cratered northern lowland plains and the heavily cratered southern highlands. Mechanisms proposed to remove ancient crust or form younger lowland crust include one or more giant impacts, subcrustal transport by mantle convection, the generation of thinner crust by plate tectonics, and mantle overturn following solidification of an early magma ocean. The age of the northern lowland crust is a significant constraint on these models. The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument on the European Space Agency's Mars Express spacecraft is providing new constraints on the martian subsurface. Here we show evidence of buried impact basins ranging in diameter from about 130 km to 470 km found over approximately 14 per cent of the northern lowlands. The number of detected buried basins >200 km in diameter indicates that the lowland crust is ancient, dating back to the Early Noachian epoch. This crater density is a lower limit because of the likelihood that not all buried basins in the area surveyed by MARSIS have been detected. An Early Noachian age for the lowland crust has been previously suggested on the basis of a large number of quasi-circular topographic depressions interpreted to be evidence of buried basins. Only a few of these depressions in the area surveyed by MARSIS, however, correlate with the detected subsurface echoes. On the basis of the MARSIS data, we conclude that the northern lowland crust is at least as old as the oldest exposed highland crust. This suggests that the crustal dichotomy formed early in the geologic evolution of Mars.

Geomorphic Assessment of the Brazos River, Texas

NASA Astrophysics Data System (ADS)

Hamilton, P.; May, D.; Haring, C.

2017-12-01

The Brazos River is a large lowland river that traverses Texas before reaching the Gulf of Mexico. Of particular interest is the Brazos River reach through Fort Bend County, TX. This area is rapidly developing and as such there are concerns regarding infrastructure near the river. Rivers maintain a state of dynamic equilibrium wherein the system makes adjustments to external perturbations. This is of no concern in the abstract; the boundary conditions for the river change and the river adjusts to accommodate the change. However, because of development near the river, natural river adjustment can have catastrophic consequences. For example, bank failure along the Brazos River in Fort Bend County threatens SH 99, a major hurricane evacuation route, as well as flood control levees and county offices. Herein we present the results of hydraulic modeling conducted through the project area as well as the results of a geomorphic assessment. The Brazos River has a regional degradational trend throughout the project area in conjunction with subtly increasing sinuosity. Additionally, headcutting has greatly widened many of the tributary valleys and increased the local sediment supply to the river. Bank failure is an issue at several locations and there have been various solutions proposed for different sites. Part of the fear in addressing issues at a particular site is that money will be spent curing the symptoms along the river without confronting the underlying regional illness. Here we show some of the regional issues and how it they potentially interact with local solutions.

Valuing river characteristics using combined site choice and participation travel cost models.

PubMed

Johnstone, C; Markandya, A

2006-08-01

This paper presents new welfare measures for marginal changes in river quality in selected English rivers. The river quality indicators used include chemical, biological and habitat-level attributes. Economic values for recreational use of three types of river-upland, lowland and chalk-are presented. A survey of anglers was carried out and using these data, two travel cost models were estimated, one to predict the numbers of trips and the other to predict angling site choice. These models were then linked to estimate the welfare associated with marginal changes in river quality using the participation levels as estimated in the trip prediction model. The model results showed that higher flow rates, biological quality and nutrient pollution levels affect site choice and influence the likelihood of a fishing trip. Consumer surplus values per trip for a 10% change in river attributes range from pound 0.04 to pound 3.93 ( pound 2001) depending on the attribute.

Regional Studies of Highland-Lowland Age Differences Across the Mars Crustal Dichotomy Boundary

NASA Technical Reports Server (NTRS)

Frey, H. V.; DeSoto, G. E.; Lazrus, R. M.

2005-01-01

Regional differences in crater retention ages (CRAs) across the Mars dichotomy boundary are compared to the global highland-lowland age difference previously determined from visible and buried impact basins based on MOLA-derived Quasi-Circular Depressions (QCDs). Here Western Arabia (WA) is compared with Ismenius Lacus (IL). We find the buried lowlands in the two regions have total CRAs essentially identical to the global average. Even more intriguing, the WA cratered terrain appears to have a CRA like that of the adjacent buried lowlands,

Watershed scale spatial variability in dissolved and total organic and inorganic carbon in contrasting UK catchments

NASA Astrophysics Data System (ADS)

Cumberland, S.; Baker, A.; Hudson, N. J.

2006-12-01

Approximately 800 organic and inorganic carbon analyses have been undertaken from watershed scale and regional scale spatial surveys in various British catchments. These include (1) a small (<100 sq-km) urban catchment (Ouseburn, N England); (2) a headwater, lowland agricultural catchment (River Tern, C England) (3) a large UK catchment (River Tyne, ~3000 sq-km) and (4) a spatial survey of ~300 analyses from rivers from SW England (~1700 sq-km). Results demonstrate that: (1) the majority of organic and inorganic carbon is in the dissolved (DOC and DIC) fractions; (2) that with the exception of peat rich headwaters, DIC concentration is always greater than DOC; (3) In the rural River Tern, riverine DOC and DIC are shown to follow a simple end- member mixing between DIC (DOC) rich (poor) ground waters and DOC (DIC) rich (poor) riparian wetlands for all sample sites. (4) In the urbanized Ouseburn catchment, although many sample sites also show this same mixing trend, some tributaries follow a pollutant trend of simultaneous increases in both DOC and DIC. The Ouseburn is part of the larger Tyne catchment: this larger catchment follows the simple groundwater DIC- soil water DOC end member mixing model, with the exception of the urban catchments which exhibit an elevated DIC compared to rural sites. (5) Urbanization is demonstrated to increase DIC compared to equivalent rural catchments; this DIC has potential sources including diffuse source inputs from the dissolution of concrete, point sources such as trade effluents and landfill leachates, and bedrock derived carbonates relocated to the soil dissolution zone by urban development. (6) DIC in rural SW England demonstrates that spatial variability in DIC can be attributed to variations in geology; but that DIC concentrations in the SW England rivers dataset are typically lower than the urbanized Tyne catchments despite the presence of carbonate bedrock in many of the sample catchments in the SW England dataset. (7

The potential impact of green agendas on historic river landscapes: Numerical modelling of multiple weir removal in the Derwent Valley Mills world heritage site, UK

NASA Astrophysics Data System (ADS)

Howard, A. J.; Coulthard, T. J.; Knight, D.

2017-09-01

The exploitation of river systems for power and navigation has commonly been achieved through the installation of a variety of in-channel obstacles of which weirs in Britain are amongst the most common. In the UK, the historic value of many of these features is recognised by planning designations and protection more commonly associated with historic buildings and other major monuments. Their construction, particularly in the north and west of Britain, has often been associated with industries such as textiles, chemicals, and mining, which have polluted waterways with heavy metals and other contaminants. The construction of weirs altered local channel gradients resulting in sedimentation upstream with the potential as well for elevated levels of contamination in sediments deposited there. For centuries these weirs have remained largely undisturbed, but as a result of the growth in hydropower and the drive to improve water quality under the European Union's Water Framework Directive, these structures are under increasing pressure to be modified or removed altogether. At present, weir modifications appear to be considered largely on an individual basis, with little focus on the wider impacts this might have on valley floor environments. Using a numerical modelling approach, this paper simulates the removal of major weirs along a 24-km stretch of the river Derwent, Derbyshire, UK, designated as a UNESCO World Heritage Site. The results suggest that although removal would not result in significant changes to the valley morphology, localised erosion would occur upstream of structures as the river readjusts its base level to new boundary conditions. Modelling indicates that sediment would also be evacuated away from the study area. In the context of the Derwent valley, this raises the potential for the remobilisation of contaminants (legacy sediments) within the wider floodplain system, which could have detrimental, long-term health and environmental implications for the

Comparison of AMSR-E and SSM/I snow parameter retrievals over the Ob river basin

USGS Publications Warehouse

Mognard, N.M.; Grippa, M.; LeToan, T.; Kelly, R.E.J.; Chang, A.T.C.; Josberger, E.G.

2004-01-01

Passive microwave observations from the Advanced Microwave Scanning Radiometer - EOS (AMSR-E) and from the Special Sensor Microwave Imager (SSM/I) are used to analyse the evolution of the snow pack in the Ob river basin during the snow season of 2002-03. The Ob river is the biggest Russian river with respect to its watershed area (2 975 000 km2). The Ob originates in the Altai mountains and flows northward across the vast West Siberian lowland towards the Arctic Ocean. The majority of snow cover is contained in the lowlands rather than in mountainous regions and persists for six months or more. During the snow season, surface air temperatures are very cold. Therefore, the combination of cold dry snow and large areas of uniform topography is ideal for snowpack extent and water equivalent retrievals from passive microwave observations. The thermal gradient through the snow pack is estimated and used to model the growth of the snow grain size and to compute the evolution of the passive microwave derived snow depth over the region. A comparison between the AMSR-E and SSM/I estimates is performed and the differences between the snow parameters from the two satellite instruments are analysed.

Potential interaction between transport and stream networks over the lowland rivers in Eastern India.

PubMed

Roy, Suvendu; Sahu, Abhay Sankar

2017-07-15

Extension of transport networks supports good accessibility and associated with the development of a region. However, transport lines have fragmented the regional landscape and disturbed the natural interplay between rivers and their floodplains. Spatial analysis using multiple buffers provides information about the potential interaction between road and stream networks and their impact on channel morphology of a small watershed in the Lower Gangetic Plain. Present study is tried to understand the lateral and longitudinal disconnection in headwater stream by rural roads with the integration of geoinformatics and field survey. Significant (p < 0.001) growth of total road length and number of road-stream crossing in the last five decades (1970s-2010s) contribute to making longitudinal and lateral disconnection in the fluvial system of Kunur River Basin. Channel geometry from ten road-stream crossings shows significant (p = 0.01) differences between upstream and downstream of crossing structure and created problems like downstream scouring, increased drop height at outlet, formation of stable bars, severe bank erosion, and make barriers for river biota. The hydro-geomorphic processes are also adversely affected due to lateral disconnection and input of fine to coarse sediments from the river side growth of unpaved road (1922%). Limited streamside development, delineation of stream corridor, regular monitoring and engineering efficiency for the construction of road and road-stream crossing might be effective in managing river geomorphology and riverine landscape. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthetic river valleys: Creating prescribed topography for form-process inquiry and river rehabilitation design

NASA Astrophysics Data System (ADS)

Brown, R. A.; Pasternack, G. B.; Wallender, W. W.

2014-06-01

mountain, lowland, and hybrid synthetic river valleys. To conclude, recommended advances such as multithread channels are discussed along with potential applications.

Eastern boundary of the Siletz terrane in the Puget Lowland from gravity and magnetic modeling with implications for seismic hazard analysis

NASA Astrophysics Data System (ADS)

Anderson, M. L.; Blakely, R. J.; Wells, R. E.; Dragovich, J.

2011-12-01

The forearc of the Cascadia subduction zone in coastal Oregon and Washington is largely composed of a 15-30 km-thick stack of basalt flows comprising the Crescent Formation (WA) and Siletz River Volcanics (OR), and collectively termed the Siletz terrane. We are developing 3-D structural maps of the Puget Lowland to distinguish older and currently active structures for seismic hazard analysis. The boundaries of the Siletz terrane in particular may strongly influence crustal rheology and neotectonic structures of the region. Careful analysis of the areal extent of this terrane will also facilitate more accurate interpretation of seismic data and gravity anomalies, which will help define the extent and shape of overlying basins. Absence of extensive outcrop in the Lowland and a widespread veneer of Quaternary deposits require extensive subsurface geophysical studies to establish Lowland-wide crustal structure. Previous studies have used active seismic surveys and interpretation of existing industry seismic data, with several studies using gravity and magnetic data or passive-source tomography support. However, steeply dipping boundaries in the mid-crust are difficult targets for seismic study. We need to independently discriminate between potential models established by seismic data using gravity and magnetic datasets. In the Puget Lowland the Siletz is a region of high seismic wave speed, density, and magnetic susceptibility, and therefore its mid-crustal boundaries are good targets for definition by gravity and magnetic data. We present interpretations of gravity and magnetic anomalies for the Puget Lowland region that together establish the most likely position and structure of the Crescent Formation boundary in the mid-upper crust. Well-constrained physical properties of Crescent basalts inform our aeromagnetic map interpretation and give us baseline values for constructing three two-dimensional models by simultaneous forward modeling of aeromagnetic and isostatic

Effects of beneficial microorganisms on lowland rice development.

PubMed

Nascente, Adriano Stephan; de Filippi, Marta Cristina Corsi; Lanna, Anna Cristina; de Sousa, Thatyane Pereira; de Souza, Alan Carlos Alves; da Silva Lobo, Valácia Lemes; da Silva, Gisele Barata

2017-11-01

Microorganisms can promote plant growth by increasing phytomass production, nutrient uptake, photosynthesis rates, and grain yield, which can result in higher profits for farmers. However, there is limited information available about the physiological characteristics of lowland rice after treatment with beneficial microorganisms in the tropical region. This study aimed to determine the effects of different beneficial microorganisms and various application forms on phytomass production, gas exchange, and nutrient contents in the lowland rice cultivar 'BRS Catiana' in a tropical region. The experiment was performed under greenhouse conditions utilizing a completely randomized design and a 7 × 3 + 1 factorial scheme with four replications. The treatments consisted of seven microorganisms, including the rhizobacterial isolates BRM 32113, BRM 32111, BRM 32114, BRM 32112, BRM 32109, and BRM 32110 and Trichoderma asperellum pooled isolates UFRA-06, UFRA-09, UFRA-12, and UFRA-52, which were applied using three different methods (microbiolized seed, microbiolized seed + soil drenched with a microorganism suspension at 7 and 15 days after sowing (DAS), and microbiolized seed + plant spraying with a microorganism suspension at 7 and 15 DAS) with a control (water). The use of microorganisms can provide numerous benefits for rice in terms of crop growth and development. The microorganism types and methods of application positively and differentially affected the physiological characteristics evaluated in the experimental lowland rice plants. Notably, the plants treated with the bioagent BRM 32109 on the seeds and on seeds + soil produced plants with the highest dry matter biomass, gas exchange rate, and N, P, Fe, and Mg uptake. Therefore, our findings indicate strong potential for the use of microorganisms in lowland rice cultivation systems in tropical regions. Currently, an additional field experiment is in its second year to validate the beneficial result reported

Herpetofauna of lowland bottomlands of southeastern Arizona: a comparison of sites

Treesearch

Philip C. Rosen; William R. Radke; Dennis J. Caldwell

2005-01-01

We intensively sampled the riparian herpetofauna at three sites in southeastern Arizona, a canyon site, Leslie Canyon, and two lowland sites, San Bernardino NWR and Empire-Ci¨¦nega Creek at Las Ci¨¦negas National Conservation Area. We also compiled a list of herpetofaunal records for the original lowland riparian area at Tucson using museum records. The herpetofaunas...

Lowland copperhead (Austrelaps superbus) envenomation causing severe neuromuscular paralysis in a dog.

PubMed

Wright, L V; Indrawirawan, Y H

2017-06-01

A case of lowland copperhead snake (Austrelaps superbus) envenomation in a dog is described. The dog developed severe and prolonged neuromuscular paralysis, including ventilatory failure. The dog was treated successfully with antivenom, intravenous fluids and mechanical ventilation. The toxic components of lowland copperhead snake venom are reviewed. © 2017 Australian Veterinary Association.

The influence of riparian vegetation on the energy input of the rivers Lafnitz and Pinka

NASA Astrophysics Data System (ADS)

Holzapfel, Gerda; Rauch, Hans Peter; Weihs, Philipp; Trimmel, Heidelinde; Formayer, Herbert; Leitner, Patrick; Graf, Wolfram; Melcher, Andreas; Dossi, Florian

2013-04-01

In Central Europe freshwater ecosystems have to deal with a loss of habitat structures due to channelisation and standardisation. Unimpaired streams and rivers are very rare, which leads to a few, remaining populations of sensitive invertebrate species which are severely fragmented. This progress is mainly noticed in lowland rivers in agricultural intensely used areas, where habitat degradation and pollution affect the ecosystems. Additional pressures on the freshwater systems will be expected due to climate change effects. In the Austrian Lowlands, an increase of air temperature about 2-2.5 °C is predicted till 2040. This will in turn lead to the highest increase in water temperature in the lowland rivers of the "Hungarian Plains", Ecoregion 11 on which the impacts of climate change will most likely be highest in Austria. Global warming on its own may lead to severe changes in aquatic ecosystems. Human impacts increase the negative effects even more. Main factors for a sustainable survival of benthic invertebrates and fishes are closely connected with parameters like water temperature, the availability of oxygen and nutrients, or radiation and nutrients for primary production which are closely related to climate. Natural bank vegetation reduces the influx of solar radiation as well as it forms a microclimate of its own and could provide very important niches for terrestrial and aquatic stages. Riparian areas with trees provide direct shade for the water body and thus avoiding the corresponding increase in water temperature. Wide riparian wooded areas can even decrease evaporation and increase the relative air humidity, which contributes to reducing water temperature. Input of deadwood like trees or logs represents essential habitats for invertebrates and fish assemblages. Its presence is one essential drivers of bed-morphology creating heterogeneous instream habitat patterns. In the framework of the project BIO_CLIC the potential of riparian vegetation to

Palaeoflood evidence on the River Nore, South East Ireland

NASA Astrophysics Data System (ADS)

Fleming, Ciara; Turner, Jonathan; Bourke, Mary

2017-04-01

Past geomorphic changes can be detected in sediment sinks, through the investigation of natural sediment archives. Since the advent of palaeoflood hydrology in the 1980s, numerous authors have demonstrated that such sediment deposits record valuable evidence of past flooding events. Many of these studies have focussed on fluvial systems in arid environments, with bedrock channels proving to be particularly successful field sites. In some districts, the collected datasets are now routinely employed to augment analyses of flood frequency and magnitude, which have traditionally relied on extrapolation of short hydrometric datasets. This study targets river reaches in a temperate humid environment, with a predominantly alluvial channel. The River Nore is one of the largest catchments draining South East Ireland. It is situated in a valley with an inherited glacial legacy and is principally a lowland river catchment. Specific morphological zones have been targeted which are optimal for flood deposit preservation, including palaeochannels, tributary junctions and floodplain overbank settings.There are a variety of anthropogenic pressures evident in this landscape. Among them are channelisation of select tributaries, a legacy of coal mining in the upland Carboniferous limestones, and the installation of man-made obstacles or modifications along the length of the river channel such as sluices and weirs. Regarding land-use, the majority of the catchment is dominated by agriculture, mainly pasture with some tillage. This study investigates palaeoflood evidence in the River Nore catchment and examines the development of the river floodplain using a variety of complementary field and desk-based methods. The sub-surface and micro-topography of river reaches are investigated using Ground Penetrating Radar (GPR) and Unmanned Aerial Vehicle (UAV) technology. Flood deposits have been characterised by examination of bank exposures and sediment cores. Installation of sediment traps

Herbivory and nutrient limitation protect warming tundra from lowland species' invasion and diversity loss.

PubMed

Eskelinen, Anu; Kaarlejärvi, Elina; Olofsson, Johan

2017-01-01

Herbivory and nutrient limitation can increase the resistance of temperature-limited systems to invasions under climate warming. We imported seeds of lowland species to tundra under factorial treatments of warming, fertilization, herbivore exclusion and biomass removal. We show that warming alone had little impact on lowland species, while exclusion of native herbivores and relaxation of nutrient limitation greatly benefitted them. In contrast, warming alone benefitted resident tundra species and increased species richness; however, these were canceled by negative effects of herbivore exclusion and fertilization. Dominance of lowland species was associated with low cover of tundra species and resulted in decreased species richness. Our results highlight the critical role of biotic and abiotic filters unrelated to temperature in protecting tundra under warmer climate. While scarcity of soil nutrients and native herbivores act as important agents of resistance to invasions by lowland species, they concurrently promote overall species coexistence. However, when these biotic and abiotic resistances are relaxed, invasion of lowland species can lead to decreased abundance of resident tundra species and diminished diversity. © 2016 John Wiley & Sons Ltd.

Use of historically fishless high-mountain lakes and streams by neartic River Otters (Lontra canadensis) in California

Treesearch

Justin M. Garwood; Roland A. Knapp; Karen L. Pope; Robert L. Grasso; Michael L. Magnuson; Jeff R. Maurer

2013-01-01

In California, River Otters (Lontra canadensis) are most commonly associated with food-rich lowland aquatic habitats where they forage primarily on fish and crustaceans. Their distribution in high-elevation montane regions of the state, areas in which fish and crayfish were absent historically, is largely unknown.We compiled occurrence records of...

Conclusions to the special issue of Science of the Total Environment concerning 'The water quality of UK rivers entering the North Sea'.

PubMed

Neal, C; House, W A; Leeks, G J; Whitton, B A; Williams, R J

2000-05-05

This paper presents an overview of the water quality functioning of eastern UK rivers draining into the North Sea. It summarises the results of three special issues of Science of the Total Environment and related work and complements a companion bibliography (Neal and Turner, 2000, this volume). The rivers are described in straightforward broad terms, and the reader is guided via the bibliography to the special volumes for the detailed findings. The water quality is shown to be highly variable over space and time. The changes over the past 300 years reflect first the transition from a rural society to the major impact of the industrial revolution and subsequently to one of the worlds' most successful environmental cleanups. The present water quality reflects the relative impacts of diffuse agricultural sources, urban and industrial point source discharges together with background inputs associated with geology: all these can be modified by within-river processes associated with physical mixing, biology and inorganic reactions. The work is set within the context of water quality, modelling and flux outputs to the North Sea and contemporary and future environmental research and management needs. A range of environmental impact studies is included. The detailed information is now available on a major and easily accessible database.

A method of estimating in-stream residence time of water in rivers

NASA Astrophysics Data System (ADS)

Worrall, F.; Howden, N. J. K.; Burt, T. P.

2014-05-01

This study develops a method for estimating the average in-stream residence time of water in a river channel and across large catchments, i.e. the time between water entering a river and reaching a downstream monitoring point. The methodology uses river flow gauging data to integrate Manning's equation along a length of channel for different percentile flows. The method was developed and tested for the River Tees in northern England and then applied across the United Kingdom (UK). The study developed methods to predict channel width and main channel length from catchment area. For an 818 km2 catchment with a channel length of 79 km, the in-stream residence time at the 50% exceedence flow was 13.8 h. The method was applied to nine UK river basins and the results showed that in-stream residence time was related to the average slope of a basin and its average annual rainfall. For the UK as a whole, the discharge-weighted in-stream residence time was 26.7 h for the median flow. At median flow, 50% of the discharge-weighted in-stream residence time was due to only 6 out of the 323 catchments considered. Since only a few large rivers dominate the in-stream residence time, these rivers will dominate key biogeochemical processes controlling export at the national scale. The implications of the results for biogeochemistry, especially the turnover of carbon in rivers, are discussed.

Geologic map of the Skykomish River 30- by 60-minute quadrangle, Washington

USGS Publications Warehouse

Tabor, R.W.; Frizzell, D.A.; Booth, D.B.; Waitt, R.B.; Whetten, J.T.; Zartman, R.E.

1993-01-01

From the eastern-most edges of suburban Seattle, the Skykomish River quadrangle stretches east across the low rolling hills and broad river valleys of the Puget Lowland, across the forested foothills of the North Cascades, and across high meadowlands to the bare rock peaks of the Cascade crest. The Straight Creek Fault, a major Pacific Northwest structure which almost bisects the quadrangle, mostly separates unmetamorphosed and low-grade metamorphic Paleozoic and Mesozoic oceanic rocks on the west from medium- to high-grade metamorphic rocks on the east. Within the quadrangle the lower grade rocks are mostly Mesozoic melange units. To the east, the higher-grade terrane is mostly the Chiwaukum Schist and related gneisses of the Nason terrane and invading mid-Cretaceous stitching plutons. The Early Cretaceous Easton Metamorphic Suite crops out on both sides of the Straight Creek fault and records it's dextral displacement. On the south margin of the quadrangle, the fault separates the lower Eocene Swauk Formation on the east from the upper Eocene and Oligocene(?) Naches Formation and, farther north, it's correlative Barlow Pass Volcanics the west. Stratigraphically equivalent rocks ot the Puget Group crop out farther to the west. Rocks of the Cascade magmatic arc are mostly represented by Miocene and Oligocene plutons, including the Grotto, Snoqualmie, and Index batholiths. Alpine river valleys in the quadrangle record multiple advances and retreats of alpine glaciers. Multiple advances of the Cordilleran ice sheet, originating in the mountains of British Columbia, Canada, have left an even more complex sequence of outwash and till along the western mountain front, up these same alpine river valleys, and over the Puget Lowland.

Comparison of leaf anatomy on some Nepenthes spp. (Nepenthaceae) from highland and lowland habitat in Indonesia

NASA Astrophysics Data System (ADS)

Arimy, N. Q.; Nisyawati, Metusala, D.

2017-07-01

Nepenthes (Nepenthaceae) is one of the unique plants with pitcher to absorb nutritional needs. This dicotyledonous plant is able to live in the lowland and highland. The difference of their habitat may influence its anatomical structures, such in leaves. This study aimed to compare the anatomy of lowland and highland Nepenthes leaves. We examined Nepenthes rafflesiana and N. mirabilis from the group of lowland Nepenthes. We also examined Nepenthes aristolochioides and N. singalana from the group of highland Nepenthes. Each species was represented by three adult leaves from 1-3 individual plants. Each leaf was made transverse section by using a hand mini microtome and the paradermal section was made by leaf screaping technique. Paradermal and the transverse section were dehydrated by using graded series of alcohol. Transverse section was stained with safranin 1 % and fastgreen 1 %, while the paradermal section with safranin 1 %. Microscopic observations were performed at Bioimaging Laboratory, Universitas Indonesia, Depok using a light microscope. The results showed there are differences in the anatomy structure between these two habitats. Highland Nepenthes has thicker and larger hypodermis than lowland Nepenthes. Cuticle layer in the highland Nepenthes was thicker than the lowland Nepenthes. Nectary gland on the highland Nepenthes was thicker and larger than the lowland Nepenthes. In addition, highland Nepenthes has bigger and fewer stomata density than the lowland Nepenthes.

Geomorphic analysis of the river response to sedimentation downstream of Mount Rainier, Washington

USGS Publications Warehouse

Czuba, Jonathan A.; Magirl, Christopher S.; Czuba, Christiana R.; Curran, Christopher A.; Johnson, Kenneth H.; Olsen, Theresa D.; Kimball, Halley K.; Gish, Casey C.

2012-01-01

A study of the geomorphology of rivers draining Mount Rainier, Washington, was completed to identify sources of sediment to the river network; to identify important processes in the sediment delivery system; to assess current sediment loads in rivers draining Mount Rainier; to evaluate if there were trends in streamflow or sediment load since the early 20th century; and to assess how rates of sedimentation might continue into the future using published climate-change scenarios. Rivers draining Mount Rainier carry heavy sediment loads sourced primarily from the volcano that cause acute aggradation in deposition reaches as far away as the Puget Lowland. Calculated yields ranged from 2,000 tonnes per square kilometer per year [(tonnes/km2)/yr] on the upper Nisqually River to 350 (tonnes/km2)/yr on the lower Puyallup River, notably larger than sediment yields of 50–200 (tonnes/km2)/yr typical for other Cascade Range rivers. These rivers can be assumed to be in a general state of sediment surplus. As a result, future aggradation rates will be largely influenced by the underlying hydrology carrying sediment downstream. The active-channel width of rivers directly draining Mount Rainier in 2009, used as a proxy for sediment released from Mount Rainier, changed little between 1965 and 1994 reflecting a climatic period that was relatively quiet hydrogeomorphically. From 1994 to 2009, a marked increase in geomorphic disturbance caused the active channels in many river reaches to widen. Comparing active-channel widths of glacier-draining rivers in 2009 to the distance of glacier retreat between 1913 and 1994 showed no correlation, suggesting that geomorphic disturbance in river reaches directly downstream of glaciers is not strongly governed by the degree of glacial retreat. In contrast, there was a correlation between active-channel width and the percentage of superglacier debris mantling the glacier, as measured in 1971. A conceptual model of sediment delivery processes

The potential for dams to impact lowland meandering river floodplain geomorphology.

PubMed

Marren, Philip M; Grove, James R; Webb, J Angus; Stewardson, Michael J

2014-01-01

The majority of the world's floodplains are dammed. Although some implications of dams for riverine ecology and for river channel morphology are well understood, there is less research on the impacts of dams on floodplain geomorphology. We review studies from dammed and undammed rivers and include influences on vertical and lateral accretion, meander migration and cutoff formation, avulsion, and interactions with floodplain vegetation. The results are synthesized into a conceptual model of the effects of dams on the major geomorphic influences on floodplain development. This model is used to assess the likely consequences of eight dam and flow regulation scenarios for floodplain geomorphology. Sediment starvation downstream of dams has perhaps the greatest potential to impact on floodplain development. Such effects will persist further downstream where tributary sediment inputs are relatively low and there is minimal buffering by alluvial sediment stores. We can identify several ways in which floodplains might potentially be affected by dams, with varying degrees of confidence, including a distinction between passive impacts (floodplain disconnection) and active impacts (changes in geomorphological processes and functioning). These active processes are likely to have more serious implications for floodplain function and emphasize both the need for future research and the need for an "environmental sediment regime" to operate alongside environmental flows.

The Potential for Dams to Impact Lowland Meandering River Floodplain Geomorphology

PubMed Central

Marren, Philip M.; Grove, James R.; Webb, J. Angus; Stewardson, Michael J.

2014-01-01

The majority of the world's floodplains are dammed. Although some implications of dams for riverine ecology and for river channel morphology are well understood, there is less research on the impacts of dams on floodplain geomorphology. We review studies from dammed and undammed rivers and include influences on vertical and lateral accretion, meander migration and cutoff formation, avulsion, and interactions with floodplain vegetation. The results are synthesized into a conceptual model of the effects of dams on the major geomorphic influences on floodplain development. This model is used to assess the likely consequences of eight dam and flow regulation scenarios for floodplain geomorphology. Sediment starvation downstream of dams has perhaps the greatest potential to impact on floodplain development. Such effects will persist further downstream where tributary sediment inputs are relatively low and there is minimal buffering by alluvial sediment stores. We can identify several ways in which floodplains might potentially be affected by dams, with varying degrees of confidence, including a distinction between passive impacts (floodplain disconnection) and active impacts (changes in geomorphological processes and functioning). These active processes are likely to have more serious implications for floodplain function and emphasize both the need for future research and the need for an “environmental sediment regime” to operate alongside environmental flows. PMID:24587718

Assessing the spatial and temporal variations of water quality in lowland areas, Northern Germany

NASA Astrophysics Data System (ADS)

Lam, Q. D.; Schmalz, B.; Fohrer, N.

2012-05-01

SummaryThe pollution of rivers and streams with agro-chemical contaminants has become one of the most crucial environmental problems in the world. The assessment of spatial and temporal variations of water quality influenced by point and diffuse source pollution is necessary to manage the environment sustainably in various watershed scales. The overall objectives of this study were to assess the transferability of parameter sets between lowland catchments on different scales using the ecohydrological model SWAT (Soil and Water Assessment Tool) and to evaluate the temporal and spatial patterns of water quality in the whole catchments before and after implementation of best management practices (BMPs). The study area Kielstau catchment is located in Northern Germany as typical example of lowland - flood plain landscape. Sandy, loamy and peat soils are characteristic for this area. Land use is dominated by arable land and pasture. In this study we examined two catchment areas including Kielstau catchment 50 km2 and its subcatchment, namely Moorau, with the area of 7.6 km2. The water quality of these catchments is not only influenced by diffuse sources from agricultural areas but also by point sources from municipal wastewater treatment plants (WWTPs). Diffuse sources as well as punctual entries from the WWTPs are considered in the model set-up. For this study, the calibration and validation of the model were carried out in a daily time step for flow and nutrients. The results indicate that the parameter sets could be transferred in lowland catchments with similar environmental conditions. Shallow groundwater is the major contributor to total nitrate load in the stream accounting for about 93% of the total nitrate load, while only about 7% originates in surface runoff and lateral flow. The study also indicates that applying a spatially distributed modeling approach was an appropriate method to generate source maps showing the spatial distribution of TN load from

Calcite saturation in the River Dee, NE Scotland.

PubMed

Wade, A J; Neal, C; Smart, R P; Edwards, A C

2002-01-23

The spatial and temporal variations in calcite (calcium carbonate) solubility within the Dee basin of NE Scotland were assessed using water chemistry data gathered from a network of 59 sites monitored for water quality from June 1996 to May 1997. Calcite solubility, expressed in terms of a saturation index (SIcalcite), was determined from measured streamwater pH, Gran alkalinity and calcium concentrations and water temperature. In general, the waters of the Dee system are undersaturated with respect to calcite, though the saturation index is higher during the summer months indicating a dependency on flow conditions and biological activity. Under low-flow conditions, the streamwaters are dominated by water derived from the lower soil horizons and deeper groundwater stores and therefore, ions such as Gran alkalinity and calcium are at their highest concentrations as they are derived mainly from bedrock weathering. The influence of biological activity on the carbonate system is also evident as the observed pH and estimated EpCO2 values indicate strong seasonal patterns, with the highest pH and lowest EpCO2 values occurring during the summer low-flow periods. Only at three sites in the lowland region of the catchment, during the summer low-flow period, are the waters oversaturated. As such, the Dee system represents an extreme 'end-member' case when compared to many UK rivers that span both under- and oversaturated conditions during the year. Regression analysis highlights a systematic change in the SIcalcite-pH relationship in a broad east-west direction across the Dee system. At sites draining the relatively impermeable upland areas, the regression of SIcalcite against pH gives a straight line with a gradient in the range 1.6-2.4. Correspondingly, under the most extreme alkaline conditions found at sites draining lowland agricultural areas, a straight-line relationship exists but with a gradient of unity. It is concluded that these changes in the SIcalcite

Interannual hydroclimatic variability and the 2009-2011 extreme ENSO phases in Colombia: from Andean glaciers to Caribbean lowlands

NASA Astrophysics Data System (ADS)

Bedoya-Soto, Juan Mauricio; Poveda, Germán; Trenberth, Kevin E.; Vélez-Upegui, Jorge Julián

2018-03-01

During 2009-2011, Colombia experienced extreme hydroclimatic events associated with the extreme phases of El Niño-Southern Oscillation (ENSO). Here, we study the dynamics of diverse land-atmosphere phenomena involved in such anomalous events at continental, regional, and local scales. Standardized anomalies of precipitation, 2-m temperature, total column water (TCW), volumetric soil water (VSW), temperature at 925 hPa, surface sensible heat (SSH), latent heat (SLH), evaporation (EVP), and liquid water equivalent thickness (LWET) are analyzed to assess atmosphere-land controls and relationships over tropical South America (TropSA) during 1986-2013 (long term) and 2009-2011 (ENSO extreme phases). An assessment of the interannual covariability between precipitation and 2-m temperature is performed using singular value decomposition (SVD) to identify the dominant spatiotemporal modes of hydroclimatic variability over the region's largest river basins (Amazon, Orinoco, Tocantins, Magdalena-Cauca, and Essequibo). ENSO, its evolution in time, and strong and consistent spatial structures emerge as the dominant mode of variability. In situ anomalies during both extreme phases of ENSO 2009-2011 over the Magdalena-Cauca River basins are linked at the continental scale. The ENSO-driven hydroclimatic effects extend from the diurnal cycle to interannual timescales, as reflected in temperature data from tropical glaciers and the rain-snow boundary in the highest peaks of the Central Andes of Colombia to river levels along the Caribbean lowlands of the Magdalena-Cauca River basin.

Plant basket hydraulic structures (PBHS) as a new river restoration measure.

PubMed

Kałuża, Tomasz; Radecki-Pawlik, Artur; Szoszkiewicz, Krzysztof; Plesiński, Karol; Radecki-Pawlik, Bartosz; Laks, Ireneusz

2018-06-15

River restoration has become increasingly attractive worldwide as it provides considerable benefits to the environment as well as to the economy. This study focuses on changes of hydromorphological conditions in a small lowland river recorded during an experiment carried out in the Flinta River, central Poland. The proposed solution was a pilot project of the construction of vegetative sediment traps (plant basket hydraulic structures - PBHS). A set of three PBSH was installed in the riverbed in one row and a range of hydraulic parameters were recorded over a period of three years (six measurement sessions). Changes of sediment grain size were analysed, and the amount and size of plant debris in the plant barriers were recorded. Plant debris accumulation influencing flow hydrodynamics was detected as a result of the installation of vegetative sediment traps. Moreover, various hydromorphological processes in the river were initiated. Additional simulations based on the detected processes showed that the proposed plant basket hydraulic structures can improve the hydromorphological status of the river. Copyright © 2018 Elsevier B.V. All rights reserved.

Heat waves in lowland Germany and their circulation-related conditions

NASA Astrophysics Data System (ADS)

Tomczyk, Arkadiusz M.; Sulikowska, Agnieszka

2017-09-01

The research study aimed at assessing multiannual variability of heat wave occurrence in the lowland part of Germany between 1966 and 2015 and determining the role of atmospheric circulation in their occurrence. The analysis was conducted with the use of two independent datasets, that is, the dataset of Germany's National Meteorological Service, Deutscher Wetterdienst, and American meteorological reanalysis database of the National Centre for Environmental Prediction/National Centre for Atmospheric Research. This article defines a hot day as a day with maximum temperature of >30 °C, and a heat wave as a sequence of at least three such days. The observed warming translated into an increase in a number of hot days and, consequently, an increase in the frequency of heat wave occurrence. In the analysed 50-year period, the smallest number of heat waves was observed between 1976 and 1985, and the largest number between 2006 and 2015 in the lowland part of Germany. The occurrence of heat waves in lowland Germany was related to anticyclonic circulation.

Quaternary geology of the Kenai Lowland and glacial history of the Cook Inlet region, Alaska

USGS Publications Warehouse

Karlstrom, Thor N.V.

1964-01-01

The Kenai Lowland is part of the Cook Inlet Lowland physiographic subprovince that borders Cook Inlet, a major marine reentrant along the Pacific Ocean coastline of south-central Alaska. The Cook Inlet Lowland occupies a structural trough underlain by rocks of Tertiary age and mantled by Quaternary deposits of varying thicknesses. The bordering high alpine mountains—the Aleutian and Alaska Ranges to the northwest and north and the Talkeetna, Chugach, and Kenai Mountains to the northeast and southeast—are underlain by rocks of Mesozoic and older ages.

Chemistry of uranium, thorium, and radium isotopes in the Ganga-Brahmaputra river system: Weathering processes and fluxes to the Bay of Bengal

NASA Astrophysics Data System (ADS)

Sarin, M. M.; Krishnaswami, S.; somayajulu, B. L. K.; Moore, W. S.

1990-05-01

The most comprehensive data set on uranium, thorium, and radium isotopes in the Ganga-Brahmaputra, one of the major river systems of the world, is reported here. The dissolved 238U concentration in these river waters ranges between 0.44 and 8.32 μ/1, and it exhibits a positive correlation with major cations (Na + K + Mg + Ca). The 238U /∑Cations ratio in waters is very similar to that measured in the suspended sediments, indicating congruent weathering of uranium and major cations. The regional variations observed in the [ 234U /238U ] activity ratio are consistent with the lithology of the drainage basins. The lowland tributaries (Chambal, Betwa, Ken, and Son), draining through the igneous and metamorphic rocks of the Deccan Traps and the Vindhyan-Bundelkhand Plateau, have [ 234U /238U ] ratio in the range 1.16 to 1.84. This range is significantly higher than the near equilibrium ratio (~1.05) observed in the highland rivers which drain through sedimentary terrains. The dissolved 226Ra concentration ranges between 0.03 and 0.22 dpm/1. The striking feature of the radium isotopes data is the distinct difference in the 228Ra and 226Ra abundances between the highland and lowland rivers. The lowland waters are enriched in 228Ra while the highland waters contain more 226Ra. This difference mainly results from the differences in their weathering regimes. The discharge-weighted mean concentration of dissolved 238U in the Ganga (at Patna) and in the Brahmaputra (at Goalpara) are 1.81 and 0.63 μ/1, respectively. The Ganga-Brahmaputra river system constitutes the major source of dissolved uranium to the Bay of Bengal. These rivers transport annually about 1000 tons of uranium to their estuaries, about 10% of the estimated global supply of dissolved uranium to the oceans via rivers. The transport of uranium by these rivers far exceeds that of the Amazon, although their water discharge is only about 20% of that of the Amazon. The high intensity of weathering of uranium in

Flooding Mitigation of seawalls and river embankments to storm surges in the coastal areas of Guangdong Province, China

NASA Astrophysics Data System (ADS)

Wang, Xianwei; Wang, Xina

2017-04-01

The coastal areas of Guangdong Province, China are susceptible to the destructions of tropical cyclones and storm surges. The projected global warming, coastal subsidence and sea level rise together will bring about greater flooding risk to these areas. The seawall and river embankment have played a significant role in mitigating and preventing the coastal low-land areas from the impairment of storm surges flooding and wave runup. However, few risk assessment studies in this region consider the existence of seawall and river embankment and often overestimate the risk and potential economic loss and population affected due to storm surge flooding. This study utilizes a hydraulic model to simulate the overtop flooding and compare those without seawall and river embankment using several specific tropic storm events and extreme events of tropic storm surges in different return periods of 2, 10, 20, 50, 100, 200 and 500 years. Most seawalls are 4 or 5 meters plus another meter of wave levee above the local mean sea level. The river embankments are usually 4 or 5 meter higher than the local mean sea level as well and decrease from the outer estuary to the inner riverine. The modeling results considering seawall and river embankments and from real storm surges are in agreement with on-site survey and observations, while those without infusing seawall and river embankments overestimate the inundation condition and economic loss. Modeling results demonstrate that seawall and river embankment greatly reduce the flooding risk and prevent the low-land area from inundation for most tropic storm events, e.g., for extreme events less than 20 to 50 years, in the coastal areas of Guangdong Province, China. However, the seawall and river embankment may also cause catastrophic disasters once there is an engineering failure of seawalls and river embankment, especially once encountering with an extreme typhoon event, e.g., the 1969 super typhoon Viola in Shantou China and the 2005

Global warming, elevational range shifts, and lowland biotic attrition in the wet tropics.

PubMed

Colwell, Robert K; Brehm, Gunnar; Cardelús, Catherine L; Gilman, Alex C; Longino, John T

2008-10-10

Many studies suggest that global warming is driving species ranges poleward and toward higher elevations at temperate latitudes, but evidence for range shifts is scarce for the tropics, where the shallow latitudinal temperature gradient makes upslope shifts more likely than poleward shifts. Based on new data for plants and insects on an elevational transect in Costa Rica, we assess the potential for lowland biotic attrition, range-shift gaps, and mountaintop extinctions under projected warming. We conclude that tropical lowland biotas may face a level of net lowland biotic attrition without parallel at higher latitudes (where range shifts may be compensated for by species from lower latitudes) and that a high proportion of tropical species soon faces gaps between current and projected elevational ranges.

Analysis the flash floods occurred in the South Tyne river watershed (United Kingdom) on the 17th of July 2007

NASA Astrophysics Data System (ADS)

Bain, V.; Milan, D.; Preciso, E.; Gaume, E.

2009-04-01

On the 17th, 19th and 23rd of July 2007, a series of local thunderstorms induced flash floods in the upper part of the South Tyne river in Northumberland, a rural area located near the border between England and Scotland. These events led to moderate damages in the villages and losses of livestock in local farms. They were shadowed in comparison to the widespread lowland floods that occurred throughout the UK during the same period but were nevertheless extreme events for the region. One of the affected streams, the Thinhope Burn, has been surveyed by the University of Gloucestershire during recent years. It is an active river from a geomorphological point of view. A survey conducted after the 2007 flood revealed that many of the boulders along the banks of the river, which had been deposited 50 to 100 years before, had been displaced, indicating a high return period for the flood (see EGU abstract EGU2008-A-04713). A complementary survey was conducted in July 2008 with the objective of gathering information on the discharges, the rainfall amounts and the active runoff processes. 14 cross-sections were surveyed, pictures were collected enabling a validation of peak discharge estimates, 5 witnesses were interviewed and additional rainfall data and geomorphological evidence were collected. This survey revealed that the peak discharges exceeded 5 m3/s/km2 in the most affected areas. Unfortunately, no rainfall measurements are available that would enable further analysis, including the computation of runoff rates. Nevertheless, witness accounts and field observations give a good insight into the hydrological processes indicating a significant initial storage capacity of the peat layer covering the affected watersheds. Concerning the boulders, the field observations suggest surprising and unexplained transport processes. Blocks of up to one meter diameter were displaced over short distances and deposited on the river banks without any sign of established debris flow, as

Hydrological applications of Landsat imagery used in the study of the 1973 Indus River flood, Pakistan

USGS Publications Warehouse

Deutsch, Morris; Ruggles, F.H.

1978-01-01

During August and September 1973, the Indus River Valley of Pakistan experienced one of the largest floods on record, resulting in damages to homes, businesses, public works, and crops amounting to millions of rupees. Tremendous areas of lowlands were inundated along the Indus River and major tributaries. Landsat data made it possible to easily measure the extent of flooding, totaling about 20,000 km2 within an area of about 400,000 km2 south from the Punjab to the Arabian Sea.The Indus River data were used to continue experimentation in the development of rapid, accurate, and inexpensive optical techniques of flood mapping by satellite begun in 1973 for the Mississipi River floods. The research work on the Indus River not resulted in the development of more effective procedures for optical processing of flood data and synoptically depicting flooding, but also provided potentially valuable ancillary information concerning the hydrology of much of the Indus River Basin.

Invasibility of Mediterranean-Climate Rivers by Non-Native Fish: The Importance of Environmental Drivers and Human Pressures

PubMed Central

Ilhéu, Maria; Matono, Paula; Bernardo, João Manuel

2014-01-01

Invasive species are regarded as a biological pressure to natural aquatic communities. Understanding the factors promoting successful invasions is of great conceptual and practical importance. From a practical point of view, it should help to prevent future invasions and to mitigate the effects of recent invaders through early detection and prioritization of management measures. This study aims to identify the environmental determinants of fish invasions in Mediterranean-climate rivers and evaluate the relative importance of natural and human drivers. Fish communities were sampled in 182 undisturbed and 198 disturbed sites by human activities, belonging to 12 river types defined for continental Portugal within the implementation of the European Union's Water Framework Directive. Pumpkinseed sunfish, Lepomis gibbosus (L.), and mosquitofish, Gambusia holbrooki (Girard), were the most abundant non-native species (NNS) in the southern river types whereas the Iberian gudgeon, Gobio lozanoi Doadrio and Madeira, was the dominant NNS in the north/centre. Small northern mountain streams showed null or low frequency of occurrence and abundance of NNS, while southern lowland river types with medium and large drainage areas presented the highest values. The occurrence of NNS was significantly lower in undisturbed sites and the highest density of NNS was associated with high human pressure. Results from variance partitioning showed that natural environmental factors determine the distribution of the most abundant NNS while the increase in their abundance and success is explained mainly by human-induced disturbance factors. This study stresses the high vulnerability of the warm water lowland river types to non-native fish invasions, which is amplified by human-induced degradation. PMID:25372284

Diatoms as an indicator for tile drainage flow in a German lowland catchment.

PubMed

Wu, Naicheng; Faber, Claas; Ulrich, Uta; Fohrer, Nicola

2018-01-01

The separation of runoff components within a model simulation is of great importance for a successful implementation of management measures. Diatoms could be a promising indicator for tile drainage flow due to their diverse preferences to different aquatic habitats. In this study, we collected diatom samples of 9 sites (4 tile drainage, TD, and 5 river sites, Ri) in a German lowland catchment at a weekly or biweekly time step from March to July 2013 with the aim of testing the suitability of diatoms for tile drainage flow, which is typical for lowland catchment. Planothidium lanceolatum , Ulnaria biceps , and Navicula gregaria dominated in TD sites with relative abundances of 22.2, 21.5, and 10.9%, respectively. For Ri sites, the most abundant species was Navicula lanceolata (20.5%), followed by Ulnaria biceps (12.9%), Cyclotella meneghiniana (9.5%), and Planothidium lanceolatum (9.3%). Compared with Ri sites, TD had a lower diatom density, biomass, species richness, and percentage of Aquatic/Riparian diatoms (AqRi%). However, the proportion of Riparian diatoms (RiZo%) increased at TD. Indicator value method (IndVal) revealed that the two groups (Ri and TD) were characterized by different indicator species. Fifteen taxa, including Cocconeis placentula , Cyclotella meneghiniana , N. lanceolata , and U. biceps , were significant indicators for Ri sites. Planothidium lanceolatum , Achnanthidium minutissimum , and Navicula gregaria were significant indicators for TD sites. A pronounced variation was found in the species lists of diatom community between Ri and TD water body types associated with different indicator species. With respect to hydrograph separation, these findings highlight the suitability of diatoms as an indicator for tile drainage flow. However, spatial and temporal variations of diatoms should be considered in future surveys.

Environmental impact assessment of sand mining from the small catchment rivers in the southwestern coast of India: a case study.

PubMed

Sreebha, Sreedharan; Padmalal, Damodaran

2011-01-01

In the past few decades, the demand for construction grade sand is increasing in many parts of the world due to rapid economic development and subsequent growth of building activities. This, in many of the occasions, has resulted in indiscriminate mining of sand from in-stream and floodplain areas leading to severe damages to the river basin environment. The case is rather alarming in the small catchment rivers like those draining the southwestern coast of India due to limited sand resources in their alluvial reaches. Moreover, lack of adequate information on the environmental impact of river sand mining is a major lacuna challenging regulatory efforts in many developing countries. Therefore, a scientific assessment is a pre-requisite in formulating management strategies in the sand mining-hit areas. In this context, a study has been made as a case to address the environmental impact of sand mining from the in-stream and floodplain areas of three important rivers in the southwestern coast of India namely the Chalakudy, Periyar and Muvattupuzha rivers, whose lowlands host one of the fast developing urban-cum-industrial centre, the Kochi city. The study reveals that an amount of 11.527 million ty(-1) of sand (8.764 million ty(-1) of in-stream sand and 2.763 million ty(-1) of floodplain sand) is being mined from the midland and lowland reaches of these rivers for construction of buildings and other infrastructural facilities in Kochi city and its satellite townships. Environmental Impact Assessment (EIA) carried out as a part of this investigation shows that the activities associated with mining and processing of sands have not only affected the health of the river ecosystems but also degraded its overbank areas to a large extent. Considering the degree of degradation caused by sand mining from these rivers, no mining scenario may be opted in the deeper zones of the river channels. Also, a set of suggestions are made for the overall improvement of the rivers and its

Environmental Impact Assessment of Sand Mining from the Small Catchment Rivers in the Southwestern Coast of India: A Case Study

NASA Astrophysics Data System (ADS)

Sreebha, Sreedharan; Padmalal, Damodaran

2011-01-01

In the past few decades, the demand for construction grade sand is increasing in many parts of the world due to rapid economic development and subsequent growth of building activities. This, in many of the occasions, has resulted in indiscriminate mining of sand from instream and floodplain areas leading to severe damages to the river basin environment. The case is rather alarming in the small catchment rivers like those draining the southwestern coast of India due to limited sand resources in their alluvial reaches. Moreover, lack of adequate information on the environmental impact of river sand mining is a major lacuna challenging regulatory efforts in many developing countries. Therefore, a scientific assessment is a pre-requisite in formulating management strategies in the sand mining-hit areas. In this context, a study has been made as a case to address the environmental impact of sand mining from the instream and floodplain areas of three important rivers in the southwestern coast of India namely the Chalakudy, Periyar and Muvattupuzha rivers, whose lowlands host one of the fast developing urban-cum-industrial centre, the Kochi city. The study reveals that an amount of 11.527 million ty-1 of sand (8.764 million ty-1 of instream sand and 2.763 million ty-1 of floodplain sand) is being mined from the midland and lowland reaches of these rivers for construction of buildings and other infrastructural facilities in Kochi city and its satellite townships. Environmental Impact Assessment (EIA) carried out as a part of this investigation shows that the activities associated with mining and processing of sands have not only affected the health of the river ecosystems but also degraded its overbank areas to a large extent. Considering the degree of degradation caused by sand mining from these rivers, no mining scenario may be opted in the deeper zones of the river channels. Also, a set of suggestions are made for the overall improvement of the rivers and its

Seasat synthetic aperture radar ( SAR) response to lowland vegetation types in eastern Maryland and Virginia.

USGS Publications Warehouse

Krohn, M.D.; Milton, N.M.; Segal, D.B.

1983-01-01

Examination of Seasat SAR images of eastern Maryland and Virginia reveals botanical distinctions between vegetated lowland areas and adjacent upland areas. Radar returns from the lowland areas can be either brighter or darker than returns from the upland forests. Scattering models and scatterometer measurements predict an increase of 6 dB in backscatter from vegetation over standing water. This agrees with the 30-digital number (DN) increase observed in the digital Seasat data. The density, morphology, and relative geometry of the lowland vegetation with respect to standing water can all affect the strength of the return L band signal.-from Authors

Persistent Organic Pollutants in sediment and fish in the River Thames Catchment (UK).

PubMed

Lu, Qiong; Jürgens, Monika D; Johnson, Andrew C; Graf, Carola; Sweetman, Andy; Crosse, John; Whitehead, Paul

2017-01-15

Some organic pollutants including polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs) and hexachlorobenzene (HCB) have been banned from production and use in the UK for >30years but due to their toxicity and persistence are still of concern. However, due to their hydrophobicity they are present at very low concentrations and are difficult to measure in water, and so other matrices need to be sampled in order to best assess contamination. This study measured concentrations of ΣICES 7 PCBs (PCB congeners 28, 52, 101, 118, 138, 153 and 180) and Σ6 PBDEs (PBDE congeners 28, 47, 99, 100, 153, 154) and HCB in both bed-sediments and wild roach (a common pelagic fish) in the Thames Basin. The highest sediment concentrations were detected in an urbanised tributary of the Thames, The Cut at Bracknell (HCB: 0.03-0.40μg/kg dw; ICES 7 PCBs: 4.83-7.42μg/kg dw; 6 BDEs: 5.82-23.10μg/kg dw). When concentrations were expressed on a dry weight basis, the fish were much more contaminated than the sediments, but when sediment concentrations were normalised to organic carbon concentration they were comparable to the fish lipid normalised concentrations. Thus, despite the variability in the system, both sediments and wild fish can be considered suitable for representing the level of POPs contamination of the river system given sufficient sample numbers. Copyright © 2016 Elsevier B.V. All rights reserved.

A-B-O and Rh affinities between highland and lowland Quechua-speaking Peruvian populations.

PubMed

Frisancho, A R; Klayman, J E

1975-09-01

According to the accounts of the Spanish chronicles and various historical analyses the Quechua-speaking population inhabiting the Province of Lamas in the Eastern Tropical Lowlands of Peru are descendants of the Chanca Tribes that migrated from the highlands about 500 years ago. The results of the present study indicate that in terms of the A-B-O and Rh systems the lowland Quechua-speaking population from the Province of Lamas and the highland Quechua population from the Province of Junin are more similar to each other than to other tropical tribes. Therefore, it is quite possible that the present lowland Quechua-speaking population from the Province of Lamas may be descendants of Andean populations.

RiverCare: towards self-sustaining multifunctional rivers

NASA Astrophysics Data System (ADS)

Augustijn, Denie; Schielen, Ralph; Hulscher, Suzanne

2014-05-01

Rivers are inherently dynamic water systems involving complex interactions among hydrodynamics, morphology and ecology. In many deltas around the world lowland rivers are intensively managed to meet objectives like safety, navigation, hydropower and water supply. With the increasing pressure of growing population and climate change it will become even more challenging to reach or maintain these objectives and probably also more demanding from a management point of view. In the meantime there is a growing awareness that rivers are natural systems and that, rather than further regulation works, the dynamic natural processes should be better utilized (or restored) to reach the multifunctional objectives. Currently many integrated river management projects are initiated all over the world, in large rivers as well as streams. Examples of large scale projects in the Netherlands are 'Room for the River' (Rhine), the 'Maaswerken' (Meuse), the Deltaprogramme and projects originating from the European Water Framework Directive (WFD). These projects include innovative measures executed never before on this scale and include for example longitudinal training dams, side channels, removal of bank protection, remeandering of streams, dredging/nourishment and floodplain rehabilitation. Although estimates have been made on the effects of these measures for many of the individual projects, the overall effects on the various management objectives remains uncertain, especially if all projects are considered in connection. For all stakeholders with vested interests in the river system it is important to know how that system evolves at intermediate and longer time scales (10 to 100 years) and what the consequences will be for the various river functions. If the total, integrated response of the system can be predicted, the system may be managed in a more effective way, making optimum use of natural processes. In this way, maintenance costs may be reduced, the system remains more natural

Lowland tapir distribution and habitat loss in South America.

PubMed

Cordeiro, Jose Luis Passos; Fragoso, José M V; Crawshaw, Danielle; Oliveira, Luiz Flamarion B

2016-01-01

The development of species distribution models (SDMs) can help conservation efforts by generating potential distributions and identifying areas of high environmental suitability for protection. Our study presents a distribution and habitat map for lowland tapir in South America. We also describe the potential habitat suitability of various geographical regions and habitat loss, inside and outside of protected areas network. Two different SDM approaches, MAXENT and ENFA, produced relative different Habitat Suitability Maps for the lowland tapir. While MAXENT was efficient at identifying areas as suitable or unsuitable, it was less efficient (when compared to the results by ENFA) at identifying the gradient of habitat suitability. MAXENT is a more multifaceted technique that establishes more complex relationships between dependent and independent variables. Our results demonstrate that for at least one species, the lowland tapir, the use of a simple consensual approach (average of ENFA and MAXENT models outputs) better reflected its current distribution patterns. The Brazilian ecoregions have the highest habitat loss for the tapir. Cerrado and Atlantic Forest account for nearly half (48.19%) of the total area lost. The Amazon region contains the largest area under protection, and the most extensive remaining habitat for the tapir, but also showed high levels of habitat loss outside protected areas, which increases the importance of support for proper management.

Lowland tapir distribution and habitat loss in South America

PubMed Central

Fragoso, José M.V.; Crawshaw, Danielle; Oliveira, Luiz Flamarion B.

2016-01-01

The development of species distribution models (SDMs) can help conservation efforts by generating potential distributions and identifying areas of high environmental suitability for protection. Our study presents a distribution and habitat map for lowland tapir in South America. We also describe the potential habitat suitability of various geographical regions and habitat loss, inside and outside of protected areas network. Two different SDM approaches, MAXENT and ENFA, produced relative different Habitat Suitability Maps for the lowland tapir. While MAXENT was efficient at identifying areas as suitable or unsuitable, it was less efficient (when compared to the results by ENFA) at identifying the gradient of habitat suitability. MAXENT is a more multifaceted technique that establishes more complex relationships between dependent and independent variables. Our results demonstrate that for at least one species, the lowland tapir, the use of a simple consensual approach (average of ENFA and MAXENT models outputs) better reflected its current distribution patterns. The Brazilian ecoregions have the highest habitat loss for the tapir. Cerrado and Atlantic Forest account for nearly half (48.19%) of the total area lost. The Amazon region contains the largest area under protection, and the most extensive remaining habitat for the tapir, but also showed high levels of habitat loss outside protected areas, which increases the importance of support for proper management. PMID:27672509

Tidal river dynamics: Implications for deltas

NASA Astrophysics Data System (ADS)

Hoitink, A. J. F.; Jay, D. A.

2016-03-01

Tidal rivers are a vital and little studied nexus between physical oceanography and hydrology. It is only in the last few decades that substantial research efforts have been focused on the interactions of river discharge with tidal waves and storm surges into regions beyond the limit of salinity intrusion, a realm that can extend inland hundreds of kilometers. One key phenomenon resulting from this interaction is the emergence of large fortnightly tides, which are forced long waves with amplitudes that may increase beyond the point where astronomical tides have become extinct. These can be larger than the linear tide itself at more landward locations, and they greatly influence tidal river water levels and wetland inundation. Exploration of the spectral redistribution and attenuation of tidal energy in rivers has led to new appreciation of a wide range of consequences for fluvial and coastal sedimentology, delta evolution, wetland conservation, and salinity intrusion under the influence of sea level rise and delta subsidence. Modern research aims at unifying traditional harmonic tidal analysis, nonparametric regression techniques, and the existing understanding of tidal hydrodynamics to better predict and model tidal river dynamics both in single-thread channels and in branching channel networks. In this context, this review summarizes results from field observations and modeling studies set in tidal river environments as diverse as the Amazon in Brazil, the Columbia, Fraser and Saint Lawrence in North America, the Yangtze and Pearl in China, and the Berau and Mahakam in Indonesia. A description of state-of-the-art methods for a comprehensive analysis of water levels, wave propagation, discharges, and inundation extent in tidal rivers is provided. Implications for lowland river deltas are also discussed in terms of sedimentary deposits, channel bifurcation, avulsion, and salinity intrusion, addressing contemporary research challenges.

The Hindlimb Arterial Vessels in Lowland paca (Cuniculus paca, Linnaeus 1766).

PubMed

Leal, L M; de Freitas, H M G; Sasahara, T H C; Machado, M R F

2016-04-01

This study aims to describe the origin and distribution of the hindlimb arterial vessels. Five adult lowland pacas (Cuniculus paca) were used. Stained and diluted latex was injected, caudally to the aorta. After fixation in 10% paraformaldehyde for 72 h, we dissected to visualize and identify the vessels. It was found out that the vascularization of the hindlimb in lowland paca derives from the terminal branch of the abdominal aorta. The common iliac artery divides into external iliac and internal iliac. The external iliac artery emits the deep iliac circumflex artery, the pudendal epigastric trunk, the deep femoral artery; the femoral artery originates the saphenous artery, it bifurcates into cranial and caudal saphenous arteries. Immediately after the knee joint, the femoral artery is called popliteal artery, which divides into tibial cranial and tibial caudal arteries at the level of the crural inter-osseous space. The origin and distribution of arteries in the hindlimb of lowland paca resembles that in other wild rodents, as well as in the domestic mammals. © 2014 Blackwell Verlag GmbH.

Three-dimensional geometric morphometric analysis of talar morphology in extant gorilla taxa from highland and lowland habitats.

PubMed

Knigge, Ryan P; Tocheri, Matthew W; Orr, Caley M; Mcnulty, Kieran P

2015-01-01

Western gorillas (Gorilla gorilla) are known to climb significantly more often than eastern gorillas (Gorilla beringei), a behavioral distinction attributable to major differences in their respective habitats (i.e., highland vs. lowland). Genetic evidence suggests that the lineages leading to these taxa began diverging from one another between approximately 1 and 3 million years ago. Thus, gorillas offer a special opportunity to examine the degree to which morphology of recently diverged taxa may be "fine-tuned" to differing ecological requirements. Using three-dimensional (3D) geometric morphometrics, we compared talar morphology in a sample of 87 specimens including western (lowland), mountain (highland), and grauer gorillas (lowland and highland populations). Talar shape was captured with a series of landmarks and semilandmarks superimposed by generalized Procrustes analysis. A between-group principal components analysis of overall talar shape separates gorillas by ecological habitat and by taxon. An analysis of only the trochlea and lateral malleolar facet identifies subtle variations in trochlear shape between western lowland and lowland grauer gorillas, potentially indicative of convergent evolution of arboreal adaptations in the talus. Lastly, talar shape scales differently with centroid size for highland and lowland gorillas, suggesting that ankle morphology may track body-size mediated variation in arboreal behaviors differently depending on ecological setting. Several of the observed shape differences are linked biomechanically to the facilitation of climbing in lowland gorillas and to stability and load-bearing on terrestrial substrates in the highland taxa, providing an important comparative model for studying morphological variation in groups known only from fossils (e.g., early hominins). © 2014 Wiley Periodicals, Inc.

Coupling climate and hydrological models to evaluate the impact of climate change on run of the river hydropower schemes from UK study sites

NASA Astrophysics Data System (ADS)

Pasten-Zapata, Ernesto; Jones, Julie; Moggridge, Helen

2015-04-01

As climate change is expected to generate variations on the Earth's precipitation and temperature, the water cycle will also experience changes. Consequently, water users will have to be prepared for possible changes in future water availability. The main objective of this research is to evaluate the impacts of climate change on river regimes and the implications to the operation and feasibility of run of the river hydropower schemes by analyzing four UK study sites. Run of the river schemes are selected for analysis due to their higher dependence to the available river flow volumes when compared to storage hydropower schemes that can rely on previously accumulated water volumes (linked to poster in session HS5.3). Global Climate Models (GCMs) represent the main tool to assess future climate change. In this research, Regional Climate Models (RCMs), which dynamically downscale GCM outputs providing higher resolutions, are used as starting point to evaluate climate change within the study catchments. RCM daily temperature and precipitation will be downscaled to an appropriate scale for impact studies and bias corrected using different statistical methods: linear scaling, local intensity scaling, power transformation, variance scaling and delta change correction. The downscaled variables will then be coupled to hydrological models that have been previously calibrated and validated against observed daily river flow data. The coupled hydrological and climate models will then be used to simulate historic river flows that are compared to daily observed values in order to evaluate the model accuracy. As this research will employ several different RCMs (from the EURO-CORDEX simulations), downscaling and bias correction methodologies, greenhouse emission scenarios and hydrological models, the uncertainty of each element will be estimated. According to their uncertainty magnitude, a prediction of the best downscaling approach (or approaches) is expected to be obtained. The

Investigating the impact of land cover change on peak river flow in UK upland peat catchments, based on modelled scenarios

NASA Astrophysics Data System (ADS)

Gao, Jihui; Holden, Joseph; Kirkby, Mike

2014-05-01

Changes to land cover can influence the velocity of overland flow. In headwater peatlands, saturation means that overland flow is a dominant source of runoff, particularly during heavy rainfall events. Human modifications in headwater peatlands may include removal of vegetation (e.g. by erosion processes, fire, pollution, overgrazing) or pro-active revegetation of peat with sedges such as Eriophorum or mosses such as Sphagnum. How these modifications affect the river flow, and in particular the flood peak, in headwater peatlands is a key problem for land management. In particular, the impact of the spatial distribution of land cover change (e.g. different locations and sizes of land cover change area) on river flow is not clear. In this presentation a new fully distributed version of TOPMODEL, which represents the effects of distributed land cover change on river discharge, was employed to investigate land cover change impacts in three UK upland peat catchments (Trout Beck in the North Pennines, the Wye in mid-Wales and the East Dart in southwest England). Land cover scenarios with three typical land covers (i.e. Eriophorum, Sphagnum and bare peat) having different surface roughness in upland peatlands were designed for these catchments to investigate land cover impacts on river flow through simulation runs of the distributed model. As a result of hypothesis testing three land cover principles emerged from the work as follows: Principle (1): Well vegetated buffer strips are important for reducing flow peaks. A wider bare peat strip nearer to the river channel gives a higher flow peak and reduces the delay to peak; conversely, a wider buffer strip with higher density vegetation (e.g. Sphagnum) leads to a lower peak and postpones the peak. In both cases, a narrower buffer strip surrounding upstream and downstream channels has a greater effect than a thicker buffer strip just based around the downstream river network. Principle (2): When the area of change is equal

Water availability not fruitfall modulates the dry season distribution of frugivorous terrestrial vertebrates in a lowland Amazon forest

PubMed Central

Paredes, Omar Stalin Landázuri; Norris, Darren; de Oliveira, Tadeu Gomes

2017-01-01

Terrestrial vertebrate frugivores constitute one of the major guilds in tropical forests. Previous studies show that the meso-scale distribution of this group is only weakly explained by variables such as altitude and tree basal area in lowland Amazon forests. For the first time we test whether seasonally limiting resources (water and fallen fruit) affect the dry season distribution in 25 species of terrestrial vertebrates. To examine the effects of the spatial availability of fruit and water on terrestrial vertebrates we used a standardized, regularly spaced arrangement of camera-traps within 25km2 of lowland Amazon forest. Generalized linear models (GLMs) were then used to examine the influence of four variables (altitude, distance to large rivers, distance to nearest water, and presence vs absence of fruits) on the number of photos on five functional groups (all frugivores, small, medium, large and very large frugivores) and on seven of the most abundant frugivore species (Cuniculus paca, Dasyprocta leporina, Mazama americana, Mazama nemorivaga, Myoprocta acouchy, Pecari tajacu and Psophia crepitans). A total of 279 independent photos of 25 species were obtained from 900 camera-trap days. For most species and three functional groups, the variation in the number of photos per camera was significantly but weakly explained by the GLMs (deviance explained ranging from 6.2 to 48.8%). Generally, we found that the presence of water availability was more important than the presence of fallen fruit for the groups and species studied. Medium frugivores, large-bodied frugivores, and two of the more abundant species (C. paca and P. crepitans) were recorded more frequently closer to water bodies; while none of the functional groups nor the most abundant species showed any significant relationship with the presence of fallen fruit. Two functional groups and two of the seven most common frugivore species assessed in the GLMs showed significant results with species

Water availability not fruitfall modulates the dry season distribution of frugivorous terrestrial vertebrates in a lowland Amazon forest.

PubMed

Paredes, Omar Stalin Landázuri; Norris, Darren; Oliveira, Tadeu Gomes de; Michalski, Fernanda

2017-01-01

Terrestrial vertebrate frugivores constitute one of the major guilds in tropical forests. Previous studies show that the meso-scale distribution of this group is only weakly explained by variables such as altitude and tree basal area in lowland Amazon forests. For the first time we test whether seasonally limiting resources (water and fallen fruit) affect the dry season distribution in 25 species of terrestrial vertebrates. To examine the effects of the spatial availability of fruit and water on terrestrial vertebrates we used a standardized, regularly spaced arrangement of camera-traps within 25km2 of lowland Amazon forest. Generalized linear models (GLMs) were then used to examine the influence of four variables (altitude, distance to large rivers, distance to nearest water, and presence vs absence of fruits) on the number of photos on five functional groups (all frugivores, small, medium, large and very large frugivores) and on seven of the most abundant frugivore species (Cuniculus paca, Dasyprocta leporina, Mazama americana, Mazama nemorivaga, Myoprocta acouchy, Pecari tajacu and Psophia crepitans). A total of 279 independent photos of 25 species were obtained from 900 camera-trap days. For most species and three functional groups, the variation in the number of photos per camera was significantly but weakly explained by the GLMs (deviance explained ranging from 6.2 to 48.8%). Generally, we found that the presence of water availability was more important than the presence of fallen fruit for the groups and species studied. Medium frugivores, large-bodied frugivores, and two of the more abundant species (C. paca and P. crepitans) were recorded more frequently closer to water bodies; while none of the functional groups nor the most abundant species showed any significant relationship with the presence of fallen fruit. Two functional groups and two of the seven most common frugivore species assessed in the GLMs showed significant results with species

Phylogeography of the Mekong mud snake (Enhydris subtaeniata): the biogeographic importance of dynamic river drainages and fluctuating sea levels for semiaquatic taxa in Indochina

PubMed Central

Lukoschek, Vimoksalehi; Osterhage, Jennifer L; Karns, Daryl R; Murphy, John C; Voris, Harold K

2011-01-01

During the Cenozoic, Southeast Asia was profoundly affected by plate tectonic events, dynamic river systems, fluctuating sea levels, shifting coastlines, and climatic variation, which have influenced the ecological and evolutionary trajectories of the Southeast Asian flora and fauna. We examined the role of these paleogeographic factors on shaping phylogeographic patterns focusing on a species of semiaquatic snake, Enhydris subtaeniata (Serpentes: Homalopsidae) using sequence data from three mitochondrial fragments (cytochrome b, ND4, and ATPase—2785 bp). We sampled E. subtaeniata from seven locations in three river drainage basins that encompassed most of this species’ range. Genetic diversities were typically low within locations but high across locations. Moreover, each location had a unique suite of haplotypes not shared among locations, and pairwise φST values (0.713–0.998) were highly significant between all location pairs. Relationships among phylogroups were well resolved and analysis of molecular variance (AMOVA) revealed strong geographical partitioning of genetic variance among the three river drainage basins surveyed. The genetic differences observed among the populations of E. subtaeniata were likely shaped by the Quaternary landscapes of Indochina and the Sunda Shelf. Historically, the middle and lower Mekong consisted of strongly dissected river valleys separated by low mountain ranges and much of the Sunda Shelf consisted of lowland river valleys that served to connect faunas associated with major regional rivers. It is thus likely that the contemporary genetic patterns observed among populations of E. subtaeniata are the result of their histories in a complex terrain that created abundant opportunities for genetic isolation and divergence yet also provided lowland connections across now drowned river valleys. PMID:22393504

Towards a better understanding aquatic carbon losses from lowland peatlands across England and Wales

NASA Astrophysics Data System (ADS)

Grayson, Richard; Holden, Joseph; Chapman, Pippa; Evans, Chris

2017-04-01

Hydrological fluxes in lowland peatlands can be challenging to measure but they drive poorly understood aquatic carbon fluxes which may form an important part of the overall carbon budget for peatlands. In this study we examined 11 lowland peatland sites across some of the most important fen and raised bog complexes in England and Wales including agricultural peatlands, mining sites and restoration sites. These were intensively monitored between January 2013 and December 2015. The monitoring included continual hydrological measurements and regular sampling for dissolved organic and inorganic carbon (DOC and DIC), particulate organic carbon (POC) and dissolved carbon dioxide, methane and nitrous oxide. These data were used to calculate the amount of water flowing out of each site and the total aquatic carbon loss. In addition, the hydrological data were used to provide contextual data to explain carbon flux variations between sites and help explain and model variations in gaseous carbon fluxes. The hydrology of all these lowland peat sites is typically complex with most having been drained, which when combined with their relatively flat gradients results in most having no clear single outlet. In addition the drainage networks are often used to not only drain water during periods of excess rainfall but also to maintain raised water tables during summer months when rainfall totals are low. As a result, aquatic losses were determined using a mixture of water mass balance approaches (e.g. using flux tower evapotranspiration data) and groundwater flow monitoring. The hydrology of the 11 sites was found to vary considerably, even between co-located sites, however as might be expected given the west-east rainfall gradient observed in the UK, discharge was typically highest at the Anglesey Fens sites (western Wales) and lowest at the East Anglian Fens sites (eastern England). One influence on the observed differences in discharge was the impact of vegetation type on

Effects of landuse change on the hydrologic regime of the Mae Chaem river basin, NW Thailand

NASA Astrophysics Data System (ADS)

Thanapakpawin, P.; Richey, J.; Thomas, D.; Rodda, S.; Campbell, B.; Logsdon, M.

2007-02-01

SummaryConflicts between upland shifting cultivation, upland commercial crops, and lowland irrigated agriculture cause water resource tension in the Mae Chaem watershed in Chiang Mai, Thailand. In this paper, we assess hydrologic regimes of the Mae Chaem River with landuse change. Three plausible future forest-to-crop expansion scenarios and a scenario of crop-to-forest reversal were developed based on the landcover transition from 1989 to 2000, with emphasis on influences of elevation bands and irrigation diversion. Basin hydrologic responses were simulated using the Distributed Hydrology Soil Vegetation Model (DHSVM). Meteorological data from six weather stations inside and adjacent to the Mae Chaem watershed during the period 1993-2000 were the climate inputs. Computed stream flow was compared to observed discharge at Ban Mae Mu gauge on Mae Mu river, Ban Mae Suk gauge on Mae Suk river, and at Kaeng Ob Luang, located downstream from the district town in Mae Chaem. With current assumptions, expansion of highland crop fields led to slightly higher regulated annual and wet-season water yields compared to similar expansion in the lowland-midland zone. Actual downstream water availability was sensitive to irrigation diversion. This modeling approach can be a useful tool for water allocation for small watersheds undergoing rapid commercialization, because it alerts land managers to the potential range of water supply in wet and dry seasons, and provides information on spatial distribution of basin hydrologic components.

Exchange of nitrous oxide within the Hudson Bay lowland

NASA Technical Reports Server (NTRS)

Schiller, C. L.; Hastie, D. R.

1994-01-01

The source strength of atmospheric trace gases from natural ecosystems must be quantified in order to assess the effect of such inputs on the background tropospheric chemistry. A static chamber technique and a gas exchange technique were used to determine the emissions of nitrous oxide from five sites within the Hudson Bay Lowland, as part of the Northern Wetland Study. Two mechanisms, one diffusive and the other episodic, were found likely to be responsible for the emissions of nitrous oxide. The annual diffusive flux ranged from -3.8 mg(N2O)/sq m in a treed bog to 7.9 mg(N2O)/sq m in an open fen. The addition of the episodic flux, increased this range to -2.1 mg(N2O)/sq m and 18.5 mg(N2O)/sq m respectively. These episodic emissions occurred in from 2.5% to 16.7% of the samples during the late summer peak emission period. Since the gas exchange rate could not detect the episodic emissions, it was found to be a poor method for water emission rate determination within the wetland. LANDSAT-Thermatic Mapper (TM) imagery was used to scale the emissions, from the chamber level to an integrated average over the entire Hudson Bay Lowland. The total emission rate of N2O from the Hudson Bay Lowland, was determined to be 1.2 Gg(N2O)/year, of which 80% was attributed to episodic emissions.

How Ebola impacts genetics of Western lowland gorilla populations.

PubMed

Le Gouar, Pascaline J; Vallet, Dominique; David, Laetitia; Bermejo, Magdalena; Gatti, Sylvain; Levréro, Florence; Petit, Eric J; Ménard, Nelly

2009-12-18

Emerging infectious diseases in wildlife are major threats for both human health and biodiversity conservation. Infectious diseases can have serious consequences for the genetic diversity of populations, which could enhance the species' extinction probability. The Ebola epizootic in western and central Africa induced more than 90% mortality in Western lowland gorilla population. Although mortality rates are very high, the impacts of Ebola on genetic diversity of Western lowland gorilla have never been assessed. We carried out long term studies of three populations of Western lowland gorilla in the Republic of the Congo (Odzala-Kokoua National Park, Lossi gorilla sanctuary both affected by Ebola and Lossi's periphery not affected). Using 17 microsatellite loci, we compared genetic diversity and structure of the populations and estimate their effective size before and after Ebola outbreaks. Despite the effective size decline in both populations, we did not detect loss in genetic diversity after the epizootic. We revealed temporal changes in allele frequencies in the smallest population. Immigration and short time elapsed since outbreaks could explain the conservation of genetic diversity after the demographic crash. Temporal changes in allele frequencies could not be explained by genetic drift or random sampling. Immigration from genetically differentiated populations and a non random mortality induced by Ebola, i.e., selective pressure and cost of sociality, are alternative hypotheses. Understanding the influence of Ebola on gorilla genetic dynamics is of paramount importance for human health, primate evolution and conservation biology.

Can lowland dry forests represent a refuge from avian malaria for native Hawaiian birds?

USGS Publications Warehouse

Tucker-Mohl, Katherine; Hart, Patrick; Atkinson, Carter T.

2010-01-01

Hawaii's native birds have become increasingly threatened over the past century. Introduced mosquito borne diseases such as avian malaria may be responsible for the near absence of endemic Hawaiian forest birds in low-elevation habitats. The recent recognition that some native Hawaiian forest birds may be repopulating moist lowland habitats as a result of evolved resistance to this disease has increased the conservation value of these areas. Here, we investigate whether remnant low elevation dry forests on Hawaii Island provide natural 'refuges' from mosquito-transmitted malaria by nature of their low rainfall and absence of suitable natural sources of water for mosquito breeding. Unlike lowland wet forests where high rates of disease transmission may be selecting for disease resistance, lowland dry forests may provide some refuge for native forest birds without natural resistance to malaria. We mistnetted forest birds in two lowland dry forests and tested all native birds by microscopy and serology for avian malaria caused by the Plasmodium relictum parasite. We also conducted surveys for standing water and mosquito larvae. Overall prevalence of infections with Plasmodium relictum in the Hawaii Amakihi Hemignathus virens virens was 15%. Most infected birds had lowlevel parasitemias, suggesting chronic infections. Although avian malaria is present in these lowland dry forest Amakihi populations, infection rates are significantly lower than in wet forest populations at similar elevations. Sources of breeding mosquitoes in these forests appeared to be largely anthropogenic; thus, there is potential to manage dry forests as mosquito-free habitat for Hawaii Amakihi and other Hawaiian forest birds.

Tagliamento, the king of Alpine rivers

NASA Astrophysics Data System (ADS)

Imbriani, Nadia

2016-04-01

The Tagliamento river is usually described as the king of the Alpine rivers because it is an extraordinary example of braided gravel-bed river in Europe. It flows in Friuli Venezia Giulia, a region in north-eastern Italy. It has preserved its original ecosystem which has never been changed significantly by irresponsible human interference. Therefore, vegetated islands and braid bars, due to the typical network of channels the river creates, have always been an uncontaminated natural habitat for a wide variety of species of flora and fauna. The Pinzano Bridge, near San Daniele del Friuli, collapsed on 4th November 1966 because of an overflow of water from Tagliamento. From that time, lowlands territorial authorities would like to build retention basins to prevent the river from floodings. A study about the bio-geological survey carried out from a Manzini High School project, chiefly aims to study this ecosystem, which combines the dynamic nature of the Tagliamento with the biodiversity of the whole area where it flows. In the previous years, some classes were involved in this school project. After visiting the river area and taking several photographs of it, the students had the opportunity to reflect upon the devastating environmental impact which the construction of retention basins would cause. They illustrated and analyzed both the solutions offered by some local governors and the objections raised by the World Wide Fund For Nature (WWF). In the near future, other students will continue studying the Tagliamento river so as to be able to appreciate one of the local rarities nature offers, in the hope that the unique geomorphological features of this site of undoubted scientific interest could be kept intact for a very long time.

Comparative ocular anatomy of the western lowland gorilla.

PubMed

Knapp, Stefanie; McCulley, James P; Alvarado, Thomas P; Hogan, R Nick

2007-01-01

To examine the lowland gorilla (Gorilla gorilla gorilla) eye and determine similarities to and differences between the mountain gorilla (Gorilla gorilla beringei) and the human eye. In addition, we compare our findings of G. g. gorilla to previous reports on the eye of this subspecies. A 13-year-old deceased male lowland gorilla and a 34-year-old deceased female lowland gorilla were included in the study. Gross and microscopic examinations of the formalin-fixed right eyeball of each gorilla were carried out. Globe dimensions of G. g. gorilla were similar to G. g. beringei and to humans. The limbal conjunctival epithelium and the choroid were densely pigmented. However, the distribution of the conjunctival pigment ring was different to that of G. g. beringei and the melanocytes of the choroid were unusually round. There were deep crypts in the anterior border layer of the iris, and the epithelium of the pars plana was uniquely irregular. Vertical corneal diameter was observed to be equal or greater than horizontal diameter in G. g. gorilla, which is in contrast to humans and to previous findings for G. g. beringei. Corneal thickness was closer to that of humans than to G. g. beringei. Posterior lens capsule thickness was noticeably greater than that of humans. Although some variation between the ocular anatomy of G. g. gorilla and G. g. beringei does exist, the gross and microscopic findings closely resemble each other in these two subspecies. In addition, the eye of Gorilla appears remarkably similar to the human eye. However, comparison of measurements with those in humans is somewhat limited because formalin-fixation can introduce tissue shrinkage and artifact.

An interactive modelling tool for understanding hydrological processes in lowland catchments

NASA Astrophysics Data System (ADS)

Brauer, Claudia; Torfs, Paul; Uijlenhoet, Remko

2016-04-01

Recently, we developed the Wageningen Lowland Runoff Simulator (WALRUS), a rainfall-runoff model for catchments with shallow groundwater (Brauer et al., 2014ab). WALRUS explicitly simulates processes which are important in lowland catchments, such as feedbacks between saturated and unsaturated zone and between groundwater and surface water. WALRUS has a simple model structure and few parameters with physical connotations. Some default functions (which can be changed easily for research purposes) are implemented to facilitate application by practitioners and students. The effect of water management on hydrological variables can be simulated explicitly. The model description and applications are published in open access journals (Brauer et al, 2014). The open source code (provided as R package) and manual can be downloaded freely (www.github.com/ClaudiaBrauer/WALRUS). We organised a short course for Dutch water managers and consultants to become acquainted with WALRUS. We are now adapting this course as a stand-alone tutorial suitable for a varied, international audience. In addition, simple models can aid teachers to explain hydrological principles effectively. We used WALRUS to generate examples for simple interactive tools, which we will present at the EGU General Assembly. C.C. Brauer, A.J. Teuling, P.J.J.F. Torfs, R. Uijlenhoet (2014a): The Wageningen Lowland Runoff Simulator (WALRUS): a lumped rainfall-runoff model for catchments with shallow groundwater, Geosci. Model Dev., 7, 2313-2332. C.C. Brauer, P.J.J.F. Torfs, A.J. Teuling, R. Uijlenhoet (2014b): The Wageningen Lowland Runoff Simulator (WALRUS): application to the Hupsel Brook catchment and Cabauw polder, Hydrol. Earth Syst. Sci., 18, 4007-4028.

Cervical necrotizing fasciitis and myositis in a western lowland gorilla (Gorilla gorilla gorilla).

PubMed

Allender, M C; McCain, S L; Ramsay, E C; Schumacher, J; Ilha, M R S

2009-06-01

A 39-yr-old wild-caught, female western lowland gorilla (Gorilla gorilla gorilla) died during an immobilization to assess swelling and apparent pain of the cervical region. Necropsy revealed a fistulous tract containing plant material in the oropharynx, above the soft palate, communicating with a left-sided cervical necrotizing fasciitis and myositis. Alpha-hemolytic Streptococcus and Prevotella sp. were isolated from the cervical lesion. This is a report of cervical necrotizing fasciitis in a western lowland gorilla.

Analysis of the Sediment Hydrograph of the alluvial deltas in the Apalachicola River, Florida

NASA Astrophysics Data System (ADS)

Daranpob, A.; Hagen, S.; Passeri, D.; Smar, D. E.

2011-12-01

Channel and alluvial characteristics in lowlands are the products of boundary conditions and driving forces. The boundary conditions normally include materials and land cover types, such as soil type and vegetation cover. General driving forces include discharge rate, sediment loadings, tides and waves. Deltas built up of river-transported sediment occur in depositional zones of the river mouth in flat terrains and slow currents. Total sediment load depends on two major abilities of the river, the river shear stress and capacity. The shear stress determines transport of a given sediment grain size, normally expressed as tractive force. The river capacity determines the total load or quantity of total sediments transported across a section of the river, generally expressed as the sediment loading rate. The shear stress and sediment loading rate are relatively easy to measure in the headwater and transfer zones where streams form a v-shape valley and the river begins to form defined banks compared to the deposition zone where rivers broaden across lower elevation landscapes creating alluvial forms such as deltas. Determinations of deposition and re-suspension of sediment in fluvial systems are complicated due to exerting tidal, wind, and wave forces. Cyclic forces of tides and waves repeatedly change the sediment transport and deposition rate spatially and temporally in alluvial fans. However, the influence decreases with water depth. Understanding the transport, deposition, and re-suspension of sediments in the fluvial zone would provide a better understanding of the morphology of landscape in lowland estuaries such as the Apalachicola Bay and its estuary systems. The Apalachicola River system is located in the Florida Panhandle. Shelf sedimentation process is not a strong influence in this region because it is protected by barrier islands from direct ocean forces of the Gulf of Mexico. This research explores the characteristic of suspended sediment loadings in

Keeping agricultural soil out of rivers: evidence of sediment and nutrient accumulation within field wetlands in the UK.

PubMed

Ockenden, Mary C; Deasy, Clare; Quinton, John N; Surridge, Ben; Stoate, Chris

2014-03-15

Intensification of agriculture has resulted in increased soil degradation and erosion, with associated pollution of surface waters. Small field wetlands, constructed along runoff pathways, offer one option for slowing down and storing runoff in order to allow more time for sedimentation and for nutrients to be taken up by plants or micro-organisms. This paper describes research to provide quantitative evidence for the effectiveness of small field wetlands in the UK landscape. Ten wetlands were built on four farms in Cumbria and Leicestershire, UK. Annual surveys of sediment and nutrient accumulation in 2010, 2011 and 2012 indicated that most sediment was trapped at a sandy site (70 tonnes over 3 years), compared to a silty site (40 tonnes over 3 years) and a clay site (2 tonnes over 3 years). The timing of rainfall was more important than total annual rainfall for sediment accumulation, with most sediment transported in a few intense rainfall events, especially when these coincided with bare soil or poor crop cover. Nutrient concentration within sediments was inversely related to median particle size, but the total mass of nutrients trapped was dependent on the total mass of sediment trapped. Ratios of nutrient elements in the wetland sediments were consistent between sites, despite different catchment characteristics across the individual wetlands. The nutrient value of sediment collected from the wetlands was similar to that of soil in the surrounding fields; dredged sediment was considered to have value as soil replacement but not as fertiliser. Overall, small field wetlands can make a valuable contribution to keeping soil out of rivers. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Impacts of Climate Change on the Collapse of Lowland Maya Civilization

NASA Astrophysics Data System (ADS)

Douglas, Peter M. J.; Demarest, Arthur A.; Brenner, Mark; Canuto, Marcello A.

2016-06-01

Paleoclimatologists have discovered abundant evidence that droughts coincided with collapse of the Lowland Classic Maya civilization, and some argue that climate change contributed to societal disintegration. Many archaeologists, however, maintain that drought cannot explain the timing or complex nature of societal changes at the end of the Classic Period, between the eighth and eleventh centuries ce. This review presents a compilation of climate proxy data indicating that droughts in the ninth to eleventh century were the most severe and frequent in Maya prehistory. Comparison with recent archaeological evidence, however, indicates an earlier beginning for complex economic and political processes that led to the disintegration of states in the southern region of the Maya lowlands that precedes major droughts. Nonetheless, drought clearly contributed to the unusual severity of the Classic Maya collapse, and helped to inhibit the type of recovery seen in earlier periods of Maya prehistory. In the drier northern Maya Lowlands, a later political collapse at ca. 1000 ce appears to be related to ongoing extreme drought. Future interdisciplinary research should use more refined climatological and archaeological data to examine the relationship between climate and social processes throughout the entirety of Maya prehistory.

Geologic Carbon Sequestration in a Lightly Explored Basin: the Puget-Willamette Lowland

NASA Astrophysics Data System (ADS)

Jackson, J. S.

2007-12-01

The Puget-Willamette Lowland is located between the Cascade Range and Olympic Mountains-Coast Range. Exploration for oil and gas there commenced in 1890. Over 700 wells subsequently drilled yield one commercial gas discovery. Eocene sediments deposited west of an ancestral Cascade Range include a coal-bearing sequence covering much of the Puget-Willamette Lowland. The terrestrial deposits pass into marine deposits to the west. Syn- depositional normal faulting and strike-slip faulting are evident in several sub-basins. In the southern Lowland, normal faults were modified by episodes of late Eocene and Miocene transpression, which resulted in mild inversion of older normal faults Preserved sediments indicate that local subsidence continued into Miocene- Pliocene time, and was followed in the northern Lowland by extensive Pleistocene glaciation. In the northern Lowland, Holocene faulting is recognized in outcrop and is interpreted on seismic data acquired in Puget Sound. Structures formed by early Miocene or earlier events may have trapped migrating hydrocarbons. Structures formed or modified by Holocene faulting very probably post-date hydrocarbon generation and migration. The region appears to host potential geologic sequestration targets, including coals, sandstones, and vesicular basalt flows. The size and location of potential traps is poorly constrained by present data. Experience in better explored fore arc basins suggests 10 to 30 percent of the basin may be deformed into suitable trapping geometries. Modern seismic data is required to identify potential sequestration traps. More than one well will be required to confirm the presence and size of these traps. The present boom in oil and gas drilling has created a robust environment for seismic and drilling companies, who command unprecedented rates for their services. Only one seismic crew is presently active on the West Coast, and only a few exploration drilling rigs are available. If this environment

Modelling the regulation effects of lowland polder with pumping station on hydrological processes and phosphorus loads.

PubMed

Yan, Renhua; Li, Lingling; Gao, Junfeng

2018-05-08

Exploring the hydrological regulation of a lowland polder is essential for increasing knowledge regarding the role of polders associated with pumping stations in lowlands. In this study, the Lowland Polder Hydrology and Phosphorus modelling System (PHPS) was applied to the Jianwei polder as a case study for quantifying the regulation effects of a lowland polder with pumping on discharge and phosphorus loads. The results indicate that the polder significantly affected the temporal distribution and annual amount of catchment discharge. Compared with a no-pumping scenario, an agricultural polder with pumping stations generated a sharper discharge hydrograph with higher peak-values and lower minimum-values, as well as an 8.6% reduction in average annual discharge. It also decreased the phosphorus export to downstream water bodies by 5.33 kg/hm 2 /yr because of widespread ditches and ponds, a lower hydraulic gradient, and increased retention times of surface water in ponds. Copyright © 2018 Elsevier B.V. All rights reserved.

Description of trihalomethane levels in three UK water suppliers.

PubMed

Whitaker, Heather; Nieuwenhuijsen, Mark J; Best, Nicola; Fawell, John; Gowers, Alison; Elliot, Paul

2003-01-01

Samples of drinking water are routinely analysed for four trihalomethanes (THMs), which are indicators of by-products of disinfection with chlorine, by UK water suppliers to demonstrate compliance with regulations. The THM data for 1992-1993 to 1997-1998 for three water suppliers in the north and midlands of England were made available for a UK epidemiological study of the association between disinfection by-products and adverse birth outcomes. This paper describes the THM levels in these three supply regions and discusses possible sources of variation. THM levels varied between different suppliers' water, and average THM levels were within the regulatory limits. Chloroform was the predominant THM in all water types apart from the ground water of one supplier. The supplier that distributed more ground and lowland surface water had higher dibromochloromethane (DBCM) and bromoform levels and lower chloroform levels than the other two suppliers. In the water of two suppliers, seasonal fluctuations in bromodichloromethane (BDCM) and DBCM levels were found with levels peaking in the summer and autumn. In the other water supplier, chloroform levels followed a similar seasonal trend whereas BDCM and DBCM levels did not. For all three water suppliers, chloroform levels declined throughout 1995 when there was a drought period. There was a moderate positive correlation between the THMs most similar in their structure (chloroform and BDCM, BDCM and DBCM, and DBCM and bromoform) and a slight negative correlation between chloroform and bromoform levels.

An analysis of modern pollen rain from the Maya lowlands of northern Belize

USGS Publications Warehouse

Bhattacharya, T.; Beach, T.; Wahl, D.

2011-01-01

In the lowland Maya area, pollen records provide important insights into the impact of past human populations and climate change on tropical ecosystems. Despite a long history of regional paleoecological research, few studies have characterized the palynological signatures of lowland ecosystems, a fact which lowers confidence in ecological inferences made from palynological data. We sought to verify whether we could use pollen spectra to reliably distinguish modern ecosystem types in the Maya lowlands of Central America. We collected 23 soil and sediment samples from eight ecosystem types, including upland, riparian, secondary, and swamp (bajo) forests; pine savanna; and three distinct wetland communities. We analyzed pollen spectra with non-metric multidimensional scaling (NMDS), and found significant compositional differences in ecosystem types' pollen spectra. Forested sites had spectra dominated by Moraceae/Urticaceae pollen, while non-forested sites had significant portions of Poaceae, Asteraceae, and Amaranthaceae pollen. Upland, bajo, and riparian forest differed in representation of Cyperaceae, Bactris-type, and Combretaceae/Melastomataceae pollen. High percentages of pine (Pinus), oak (Quercus), and the presence of Byrsonima characterized pine savanna. Despite its limited sample size, this study provides one of the first statistical analyses of modern pollen rain in the Maya lowlands. Our results show that pollen assemblages can accurately reflect differences between ecosystem types, which may help refine interpretations of pollen records from the Maya area. ?? 2010 Elsevier B.V.

Investigating the temporal dynamics of suspended sediment during flood events with 7Be and 210Pbxs measurements in a drained lowland catchment

PubMed Central

Le Gall, Marion; Evrard, Olivier; Foucher, Anthony; Laceby, J. Patrick; Salvador-Blanes, Sébastien; Manière, Louis; Lefèvre, Irène; Cerdan, Olivier; Ayrault, Sophie

2017-01-01

Soil erosion is recognized as one of the main processes of land degradation in agricultural areas. High suspended sediment loads, often generated from eroding agricultural landscapes, are known to degrade downstream environments. Accordingly, there is a need to understand soil erosion dynamics during flood events. Suspended sediment was therefore sampled in the river network and at tile drain outlets during five flood events in a lowland drained catchment in France. Source and sediment fallout radionuclide concentrations (7Be, 210Pbxs) were measured to quantify both the fraction of recently eroded particles transported during flood events and their residence time. Results indicate that the mean fraction of recently eroded sediment, estimated for the entire Louroux catchment, increased from 45 ± 20% to 80 ± 20% between December 2013 and February 2014, and from 65 ± 20% to 80 ± 20% in January 2016. These results demonstrate an initial flush of sediment previously accumulated in the river channel before the increasing supply of sediment recently eroded from the hillslopes during subsequent events. This research highlights the utility of coupling continuous river monitoring and fallout radionuclide measurements to increase our understanding of sediment dynamics and improve the management of soil and water resources in agricultural catchments. PMID:28169335

Synoptic Sampling to Determine Distributed Groundwater-Surface Water Nitrate Loading and Removal Potential Along a Lowland River

NASA Astrophysics Data System (ADS)

Pai, Henry; Villamizar, Sandra R.; Harmon, Thomas C.

2017-11-01

Delineating pollutant reactive transport pathways that connect local land use patterns to surface water is an important goal. This work illustrates high-resolution river mapping of salinity or specific conductance (SC) and nitrate (NO3-) as a potential part of achieving this goal. We observed longitudinal river SC and nitrate distributions using high-resolution synoptic in situ sensing along the lower Merced River (38 river km) in Central California (USA) from 2010 to 2012. We calibrated a distributed groundwater-surface water (GW-SW) discharge model for a conservative solute using 13 synoptic SC sampling events at flows ranging from 1.3 to 31.6 m3 s-1. Nitrogen loads ranged from 0.3 to 1.6 kg N d-1 and were greater following an extended high flow period during a wet winter. Applying the distributed GW-SW discharge estimates to a simplistic reactive nitrate transport model, the model reproduced observed river nitrate distribution well (RRMSE = 5-21%), with dimensionless watershed-averaged nitrate removal (kt) ranging from 0 to 0.43. Estimates were uncertain due to GW nitrate data variability, but the resulting range was consistent with prior removal estimates. At the segment scale, estimated GW-SW nitrate loading ranged from 0 to 17 g NO3- s-1 km-1. Local loading peaked near the middle of the study reach, a location that coincides with a shallow clay lens and with confined animal feed operations in close proximity to the river. Overall, the results demonstrate the potential for high-resolution synoptic monitoring to support GW-SW modeling efforts aimed at understanding and managing nonpoint source pollution.

Advance, Retreat, and Halt of Abrupt Gravel-Sand Transitions in Alluvial Rivers

NASA Astrophysics Data System (ADS)

Blom, Astrid; Chavarrías, Víctor; Ferguson, Robert I.; Viparelli, Enrica

2017-10-01

Downstream fining of bed sediment in alluvial rivers is usually gradual, but often an abrupt decrease in characteristic grain size occurs from about 10 to 1 mm, i.e., a gravel-sand transition (GST) or gravel front. Here we present an analytical model of GST migration that explicitly accounts for gravel and sand transport and deposition in the gravel reach, sea level change, subsidence, and delta progradation. The model shows that even a limited gravel supply to a sand bed reach induces progradation of a gravel wedge and predicts the circumstances required for the gravel front to advance, retreat, and halt. Predicted modern GST migration rates agree well with measured data at Allt Dubhaig and the Fraser River, and the model qualitatively captures the behavior of other documented gravel fronts. The analysis shows that sea level change, subsidence, and delta progradation have a significant impact on the GST position in lowland rivers.

Influence of deposition of fine plant debris in river floodplain shrubs on flood flow conditions - The Warta River case study

NASA Astrophysics Data System (ADS)

Mazur, Robert; Kałuża, Tomasz; Chmist, Joanna; Walczak, Natalia; Laks, Ireneusz; Strzeliński, Paweł

2016-08-01

This paper presents problems caused by organic material transported by flowing water. This material is usually referred to as plant debris or organic debris. Its composition depends on the characteristic of the watercourse. For lowland rivers, the share of the so-called small organic matter in plant debris is considerable. This includes both various parts of water plants and floodplain vegetation (leaves, stems, blades of grass, twigs, etc.). During floods, larger woody debris poses a significant risk to bridges or other water engineering structures. It may cause river jams and may lead to damming of the flowing water. This, in turn, affects flood safety and increases flood risk in river valleys, both directly and indirectly. The importance of fine plant debris for the phenomenon being studied comes down to the hydrodynamic aspect (plant elements carried by water end up on trees and shrubs, increase hydraulic flow resistance and contribute to the nature of flow through vegetated areas changed from micro-to macro-structural). The key part of the research problem under analysis was to determine qualitative and quantitative debris parameters and to establish the relationship between the type of debris and the type of land use of river valleys (crop fields, meadows and forested river sections). Another problem was to identify parameters of plant debris for various flow conditions (e.g. for low, medium and flood flows). The research also included an analysis of the materials deposited on the structure of shrubs under flood flow conditions during the 2010 flood on the Warta River.

Widespread loess-like deposit in the Martian northern lowlands identifies Middle Amazonian climate change

USGS Publications Warehouse

Skinner, James A.; Tanaka, Kenneth L.; Platz, Thomas

2014-01-01

Consistently mappable units critical to distinguishing the style and interplay of geologic processes through time are sparse in the Martian lowlands. This study identifies a previously unmapped Middle Amazonian (ca. 1 Ga) unit (Middle Amazonian lowland unit, mAl) that postdates the Late Hesperian and Early Amazonian lowland plains by >2 b.y. The unit is regionally defined by subtle marginal scarps and slopes, has a mean thickness of 32 m, and extends >3.1 × 106 km2 between lat 35°N and 80°N. Pedestal-type craterforms and nested, arcuate ridges (thumbprint terrain) tend to occur adjacent to unit mAl outcrops, suggesting that current outcrops are vestiges of a more extensive deposit that previously covered ∼16 × 106 km2. Exposed layers, surface pits, and the draping of subjacent landforms allude to a sedimentary origin, perhaps as a loess-like deposit emplaced rhythmically through atmospheric fallout. We propose that unit mAl accumulated coevally with, and at the expense of, the erosion of the north polar basal units, identifying a major episode of Middle Amazonian climate-driven sedimentation in the lowlands. This work links ancient sedimentary processes to climate change that occurred well before those implied by current orbital and spin axis models.

Andean Mountain Building Did not Preclude Dispersal of Lowland Epiphytic Orchids in the Neotropics.

PubMed

Pérez-Escobar, Oscar Alejandro; Gottschling, Marc; Chomicki, Guillaume; Condamine, Fabien L; Klitgård, Bente B; Pansarin, Emerson; Gerlach, Günter

2017-07-07

The Andean uplift is one of the major orographic events in the New World and has impacted considerably the diversification of numerous Neotropical lineages. Despite its importance for biogeography, the specific role of mountain ranges as a dispersal barrier between South and Central American lowland plant lineages is still poorly understood. The swan orchids (Cycnoches) comprise ca 34 epiphytic species distributed in lowland and pre-montane forests of Central and South America. Here, we study the historical biogeography of Cycnoches to better understand the impact of the Andean uplift on the diversification of Neotropical lowland plant lineages. Using novel molecular sequences (five nuclear and plastid regions) and twelve biogeographic models, we infer that the most recent common ancestor of Cycnoches originated in Amazonia ca 5 Mya. The first colonization of Central America occurred from a direct migration event from Amazonia, and multiple bidirectional trans-Andean migrations between Amazonia and Central America took place subsequently. Notably, these rare biological exchanges occurred well after major mountain building periods. The Andes have limited plant migration, yet it has seldom allowed episodic gene exchange of lowland epiphyte lineages such as orchids with great potential for effortless dispersal because of the very light, anemochorous seeds.

Biological and physical conditions of macroinvertebrates in reference lowland streams

NASA Astrophysics Data System (ADS)

de Brouwer, Jan; Eekhout, Joris; Verdonschot, Piet

2016-04-01

Channelisation measures taken halfway the 20th century have had destructive consequences for the diversity of the ecology in the majority of the lowland streams in countries such as the Netherlands. Currently, stream restoration measures are being implemented in these degraded lowland streams, where design principles are often based on outdated relationships between biological and physical conditions. Little is known about the reference conditions in these streams. Therefore, the aim of this research is to quantify the relationships between biological and physical conditions of macroinvertebrates in reference lowland streams. The research was conducted in four near-natural lowland streams in Central Poland. Field data were obtained during a field campaign in 2011. The following data were obtained in a 50-m reach in each of the four streams: macroinvertebrate sampling, spatial habitat patterns, bathymetry, and flow-velocity. Furthermore, water level, light sensitivity and temperature sensors were installed to obtain the temporal dynamic of these streams. Macroinvertebrates were sampled in 9 different habitat types, i.e. sand, gravel, fine organic matter, stones, branches, leaves, silt, vegetation, and wood. Macroinvertebrates were determined to the highest taxonomic level possible. Data from the bathymetrical surveys were interpolated on a grid and bathymetrical metrics were determined. Flow velocity measurements were related to habitats and flow velocity metrics were determined. Analysis of the data shows that flow conditions vary among the different habitat, with a gradient from hard substrates towards soft substrates. Furthermore, the data show that stream as a unit best explains species composition, but also specific habitat conditions, such as substrate type and flow velocity, correlate with species composition. More specific, the data shows a strong effect of wood on species composition. These findings may have implications for stream restoration design, which

Potential biocontrol actinobacteria: Rhizospheric isolates from the Argentine Pampas lowlands legumes.

PubMed

Solans, Mariana; Scervino, Jose Martin; Messuti, María Inés; Vobis, Gernot; Wall, Luis Gabriel

2016-11-01

Control of fungal plant diseases by using naturally occurring non-pathogenic microorganisms represents a promising approach to biocontrol agents. This study reports the isolation, characterization, and fungal antagonistic activity of actinobacteria from forage soils in the Flooding Pampa, Argentina. A total of 32 saprophytic strains of actinobacteria were obtained by different isolation methods from rhizospheric soil of Lotus tenuis growing in the Salado River Basin. Based on physiological traits, eight isolates were selected for their biocontrol-related activities such as production of lytic extracellular enzymes, siderophores, hydrogen cyanide (HCN), and antagonistic activity against Cercospora sojina, Macrophomia phaseolina, Phomopsis sp., Fusarium oxysporum, and Fusarium verticilloides. These actinobacteria strains were characterized morphologically, physiologically, and identified by using molecular techniques. The characterization of biocontrol-related activities in vitro showed positive results for exoprotease, phospholipase, fungal growth inhibition, and siderophore production. However, none of the strains was positive for the production of hydrogen cyanide (HCN). Streptomyces sp. MM140 presented the highest index for biocontrol, and appear to be promising pathogenic fungi biocontrol agents. These results show the potential capacity of actinobacteria isolated from forage soils in the Argentine Pampas lowlands as promising biocontrol agents, and their future agronomic applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The influence of exposure and physiology on microplastic ingestion by the freshwater fish Rutilus rutilus (roach) in the River Thames, UK.

PubMed

Horton, Alice A; Jürgens, Monika D; Lahive, Elma; van Bodegom, Peter M; Vijver, Martina G

2018-05-01

Microplastics are widespread throughout aquatic environments. However, there is currently insufficient understanding of the factors influencing ingestion of microplastics by organisms, especially higher predators such as fish. In this study we link ingestion of microplastics by the roach Rutilus rutilus, within the non-tidal part of the River Thames, to exposure and physiological factors. Microplastics were found within the gut contents of roach from six out of seven sampling sites. Of sampled fish, 33% contained at least one microplastic particle. The majority of particles were fibres (75%), with fragments and films also seen (22.7% and 2.3% respectively). Polymers identified were polyethylene, polypropylene and polyester, in addition to a synthetic dye. The maximum number of ingested microplastic particles for individual fish was strongly correlated to exposure (based on distance from the source of the river). Additionally, at a given exposure, the size of fish correlated with the actual quantity of microplastics in the gut. Larger (mainly female) fish were more likely to ingest the maximum possible number of particles than smaller (mainly male) fish. This study is the first to show microplastic ingestion within freshwater fish in the UK and provides valuable new evidence of the factors influencing ingestion that can be used to inform future studies on exposure and hazard of microplastics to fish. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Small Expanded Craters in the Northern Lowlands

NASA Image and Video Library

2016-08-24

This image shows many small craters over a larger degraded one in the northern lowlands. These small craters are smoother and shallower than their counterparts closer to the equator. Scientists believe this difference is a result of impact into a region with subsurface ice, which sublimates when exposed to the Martian atmosphere. This causes the crater to gradually expand and flatten after impact. http://photojournal.jpl.nasa.gov/catalog/PIA21021

Regional versus local drivers of water quality in the Windermere catchment, Lake District, UK: the dominant influence of wastewater pollution over the past 200 years.

PubMed

Moorhouse, Heather L; McGowan, Suzanne; Taranu, Zofia E; Gregory-Eaves, Irene; Leavitt, Peter R; Jones, Matthew D; Barker, Philip; Brayshaw, Susan A

2018-05-10

Freshwater ecosystems are threatened by multiple anthropogenic stressors acting over different spatial and temporal scales, resulting in toxic algal blooms, reduced water quality, and hypoxia. However, while catchment characteristics act as a 'filter' modifying lake response to disturbance, little is known of the relative importance of different drivers and possible differentiation in the response of upland remote lakes in comparison to lowland, impacted lakes. Moreover, many studies have focussed on single lakes rather than looking at responses across a set of individual, yet connected lake basins. Here we used sedimentary algal pigments as an index of changes in primary producer assemblages over the last ~200 years in a northern temperate watershed consisting of 11 upland and lowland lakes within the Lake District, UK, to test our hypotheses about landscape drivers. Specifically, we expected that the magnitude of change in phototrophic assemblages would be greatest in lowland rather than upland lakes due to more intensive human activities in the watersheds of the former (agriculture, urbanization). Regional parameters, such as climate dynamics, would be the predominant factors regulating lake primary producers in remote upland lakes and thus, synchronize the dynamic of primary producer assemblages in these basins. We found broad support for the hypotheses pertaining to lowland sites as wastewater treatment was the main predictor of changes to primary producer assemblages in lowland lakes. In contrast, upland headwaters responded weakly to variation in atmospheric temperature, and dynamics in primary producers across upland lakes were asynchronous. Collectively, these findings show that nutrient inputs from point sources overwhelm climatic controls of algae and nuisance cyanobacteria, but highlights that large-scale stressors do not always initiate coherent regional lake response. Further, a lake's position in its landscape, its connectivity and proximity to point

Hydrological Assessment of Model Performance and Scenario Analyses of Land Use Change and Climate Change in lowlands of Veneto Region (Italy)

NASA Astrophysics Data System (ADS)

Pijl, Anton; Brauer, Claudia; Sofia, Giulia; Teuling, Ryan; Tarolli, Paolo

2017-04-01

, that will need to adapt to prevent largescale floods or crop-failure. Additionally, simulations under 'business-as-usual' pathway RCP8.5 would likely amplify the polarising effects on the hydrological regime as presented here, further stressing the need for adequate adaptation. The proposed presentation at EGU 2017 will contain clear visual results of the model and quantitative scenario simulations. These results are particularly interesting, firstly because they prove how a simple conceptual model can become a powerful tool in scenario analysis of future pathways. Furthermore, they clearly indicate major challenges that lowland areas are facing in modern times - not only the 46.000 km2 Po valley, but all around the world where lowlands often host the centres of our societies and economies. REFERENCES Brauer, C., Teuling, A., Torfs, P., Uijlenhoet, R., 2014. The Wageningen Lowland Runoff Simulator (WALRUS): a lumped rainfall-runoff model for catchments with shallow groundwater. Geoscientific Model Development 7 (5), 2313-2332. Rockel, B., Will, A., Hense, A., 2008. The regional climate model COSMO-CLM (CCLM). Meteorologische Zeitschrift 17 (4), 347-348. Tarolli, P., Sofia, G., 2016. Human topographic signatures and derived geomorphic processes across landscapes. Geomorphology 255, 140-161. Vezzoli, R., Mercogliano, P., Pecora, S., Zollo, A., Cacciamani, C., 2015. Hydrological simulation of Po River (North Italy) discharge under climate change scenarios using the RCM COSMO-CLM. Science of The Total Environment 521, 346-358.

Bank storage buffers rivers from saline regional groundwater: an example from the Avon River Australia

NASA Astrophysics Data System (ADS)

Gilfedder, Benjamin; Hofmann, Harald; Cartwrighta, Ian

2014-05-01

Groundwater-surface water interactions are often conceptually and numerically modeled as a two component system: a groundwater system connected to a stream, river or lake. However, transient storage zones such as hyporheic exchange, bank storage, parafluvial flow and flood plain storage complicate the two component model by delaying the release of flood water from the catchment. Bank storage occurs when high river levels associated with flood water reverses the hydraulic gradient between surface water and groundwater. River water flows into the riparian zone, where it is stored until the flood water recede. The water held in the banks then drains back into the river over time scales ranging from days to months as the hydraulic gradient returns to pre-flood levels. If the frequency and amplitude of flood events is high enough, water held in bank storage can potentially perpetually remain between the regional groundwater system and the river. In this work we focus on the role of bank storage in buffering river salinity levels against saline regional groundwater on lowland sections of the Avon River, Victoria, Australia. We hypothesize that the frequency and magnitude of floods will strongly influence the salinity of the stream water as banks fill and drain. A bore transect (5 bores) was installed perpendicular to the river and were instrumented with head and electrical conductivity loggers measuring for two years. We also installed a continuous 222Rn system in one bore. This data was augmented with long-term monthly EC from the river. During high rainfall events very fresh flood waters from the headwaters infiltrated into the gravel river banks leading to a dilution in EC and 222Rn in the bores. Following the events the fresh water drained back into the river as head gradients reversed. However the bank water salinities remained ~10x lower than regional groundwater levels during most of the time series, and only slightly above river water. During 2012 SE Australia

Preliminary atlas of active shallow tectonic deformation in the Puget Lowland, Washington

USGS Publications Warehouse

Barnett, Elizabeth A.; Haugerud, Ralph A.; Sherrod, Brian L.; Weaver, Craig S.; Pratt, Thomas L.; Blakely, Richard J.

2010-01-01

This atlas presents an up-to-date map compilation of the geological and geophysical observations that underpin interpretations of active, surface-deforming faults in the Puget Lowland, Washington. Shallow lowland faults are mapped where observations of deformation from paleoseismic, seismic-reflection, and potential-field investigations converge. Together, results from these studies strengthen the identification and characterization of regional faults and show that as many as a dozen shallow faults have been active during the Holocene. The suite of maps presented in our atlas identifies sites that have evidence of deformation attributed to these shallow faults. For example, the paleoseismic-investigations map shows where coseismic surface rupture and deformation produced geomorphic scarps and deformed shorelines. Other maps compile results of seismic-reflection and potential-field studies that demonstrate evidence of deformation along suspected fault structures in the subsurface. Summary maps show the fault traces derived from, and draped over, the datasets presented in the preceding maps. Overall, the atlas provides map users with a visual overview of the observations and interpretations that support the existence of active, shallow faults beneath the densely populated Puget Lowland.

Li-Zn-Pb multi isotopic characterization of the Loire River Basin, France

NASA Astrophysics Data System (ADS)

Millot, R.; Desaulty, A.; Widory, D.; Bourrain, X.

2013-12-01

The Loire River in France is approximately 1010 km long and drains an area of 117 800 km2. Upstream, the Loire River flows following a south to north direction from the Massif Central down to the city of Orléans, 650 km from its source. The Loire River is one of the main European riverine inputs to the Atlantic Ocean. Over time, its basin has been exposed to numerous sources of anthropogenic metal pollutions, such as metal mining, industry, agriculture and domestic inputs. The Loire River basin is thus an excellent study site to develop new isotope systematics for tracking anthropogenic sources of metal pollutions (Zn and Pb) and also to investigate Li isotope tracing that can provide key information on the nature of weathering processes at the Loire River Basin scale. Preliminary data show that Li-Zn-Pb concentrations and isotopic compositions span a wide range in river waters of the Loire River main stream and the main tributaries. There is a clear contrast between the headwaters upstream and rivers located downstream in the lowlands. In addition, one of the major tributaries within the Massif Central (the Allier River) is clearly influenced by inputs resulting from mineralizations and thermomineral waters. The results showed that, on their own, each of these isotope systematics reveals important information about the geogenic or anthropogenic origin Li-Zn-Pb. Considered together, they are however providing a more integrated understanding of the overall budgets of these elements at the scale of the Loire River Basin.

Flow reconstructions in the Upper Missouri River Basin using riparian tree rings

NASA Astrophysics Data System (ADS)

Schook, Derek M.; Friedman, Jonathan M.; Rathburn, Sara L.

2016-10-01

River flow reconstructions are typically developed using tree rings from montane conifers that cannot reflect flow regulation or hydrologic inputs from the lower portions of a watershed. Incorporating lowland riparian trees may improve the accuracy of flow reconstructions when these trees are physically linked to the alluvial water table. We used riparian plains cottonwoods (Populus deltoides ssp. monilifera) to reconstruct discharge for three neighboring rivers in the Upper Missouri River Basin: the Yellowstone (n = 389 tree cores), Powder (n = 408), and Little Missouri Rivers (n = 643). We used the Regional Curve Standardization approach to reconstruct log-transformed discharge over the 4 months in early summer that most highly correlated to tree ring growth. The reconstructions explained at least 57% of the variance in historical discharge and extended back to 1742, 1729, and 1643. These are the first flow reconstructions for the Lower Yellowstone and Powder Rivers, and they are the furthest downstream among Rocky Mountain rivers in the Missouri River Basin. Although mostly free-flowing, the Yellowstone and Powder Rivers experienced a shift from early-summer to late-summer flows within the last century. This shift is concurrent with increasing irrigation and reservoir storage, and it corresponds to decreased cottonwood growth. Low-frequency flow patterns revealed wet conditions from 1870 to 1980, a period that includes the majority of the historical record. The 1816-1823 and 1861-1865 droughts were more severe than any recorded, revealing that drought risks are underestimated when using the instrumental record alone.

Living Rivers: Importance of Andes-Amazon Connectivity and Consequences of Hydropower Development

NASA Astrophysics Data System (ADS)

Anderson, E.

2016-12-01

The inherent dynamism of rivers along elevational and longitudinal gradients underpins freshwater biodiversity, ecosystem function, and ecosystem services in the Andean-Amazon. While this region covers only a small part of the entire Amazon Basin, its influences on downstream ecology, biogeochemistry, and human wellbeing are disproportionate with its relative small size. Seasonal flow pulses from Andean rivers maintain habitat, signal migratory fishes, and export sediment, nutrients, and organic matter to distant ecosystems—like lowland Amazonia and the Atlantic coast of Brazil. Rivers are key transportation routes, and freshwater fisheries are a primary protein source for the >30 million people that inhabit the Amazon Basin. Numerous cultural traditions depend on free-flowing Andean rivers; examples include Kukama beliefs in the underwater cities of the Marañon River, where people who have drowned in rivers whose bodies are not recovered go to live, or the pre-dawn bathing rituals of the Peruvian Shawi, who gain energy and connect with ancestors in cold, fast-flowing Andean waters. Transformations in the Andean-Amazon landscape—in particular from dams—threaten to compromise flows critical for human and ecosystem wellbeing. Presently, at least 250 hydropower dams are in operation, under construction, or proposed for Andean-Amazon rivers. This presentation will discuss regional trends in hydropower development, quantify effects of existing and proposed dams on Andean-Amazon connectivity, and examine the social and cultural importance of free-flowing Andean-Amazon rivers.

A Graphical Representation of Multiple Stressor Effects on River Eutrophication as Simulated by a Physics-Based River Quality Model

NASA Astrophysics Data System (ADS)

Hitt, O.; Hutchins, M.

2016-12-01

UK river waters face considerable future pressures, primarily from population growth and climate change. In understanding controls on river water quality, experimental studies have successfully identified response to single or paired stressors under controlled conditions. Generalised Linear Model (GLM) approaches are commonly used to quantify stressor-response relationships. To explore a wider variety of stressors physics-based models are used. Our objective is to evaluate how five different types of stressor influence the severity of river eutrophication and its impact on Dissolved Oxygen (DO) an integrated measure of river ecological health. This is done by applying a physics-based river quality model for 4 years at daily time step to a 92 km stretch in the 3445 km2 Thames (UK) catchment. To understand the impact of model structural uncertainty we present results from two alternative formulations of the biological response. Sensitivity analysis carried out using the QUESTOR model (QUality Evaluation and Simulation TOol for River systems) considered gradients of various stressors: river flow, water temperature, urbanisation (abstractions and sewage/industrial effluents), phosphate concentrations in effluents and tributaries and riparian tree shading (modifying the light input). Scalar modifiers applied to the 2009-12 time-series inputs define the gradients. The model has been run for each combination of the values of these 5 variables. Results are analysed using graphical methods in order to identify variation in the type of relationship between different pairs of stressors on the system response. The method allows for all outputs from each combination of stressors to be displayed in one graphic and so showing the results of hundreds of model runs simultaneously. This approach can be carried out for all stressor pairs, and many locations/determinands. Supporting statistical analysis (GLM) reinforces the findings from the graphical analysis. Analysis suggests that

The Amazon at sea: Onset and stages of the Amazon River from a marine record, with special reference to Neogene plant turnover in the drainage basin

NASA Astrophysics Data System (ADS)

Hoorn, Carina; Bogotá-A, Giovanni R.; Romero-Baez, Millerlandy; Lammertsma, Emmy I.; Flantua, Suzette G. A.; Dantas, Elton L.; Dino, Rodolfo; do Carmo, Dermeval A.; Chemale, Farid

2017-06-01

The Amazon submarine fan is a large sediment apron situated offshore Pará (Brazil) and represents the most distal extent of the Amazon River. The age of onset of this transcontinental river remains debated, yet is of great importance for understanding biotic evolutionary processes on land and at sea. Here we present new geochemical and palynological data from a borehole drilled at the continental slope and dated based on nannofossil biostratigraphy. We found that sediments of mixed source (craton and adjacent) occur at least from the late Oligocene (NP25) to late Miocene (NN9), and that the earliest Andes-derived sediments occur in NN10 (late Miocene). Our geochemical record indicates an onset of the transcontinental Amazon River between 9.4 and 9 Ma, which postdates the regional unconformity by 1 to 1.5 My. The shift in sediment geochemistry is more gradually replicated in the palynological record by a change from coastal plain and tropical lowland taxa to a mixture of tropical lowland, and montane forest to open Andean taxa. In particular, the appearance of taxa such as Jamesonia and Huperzia, followed by Valeriana, Polylepis-Acaena, Lysipomia and Plantago (with a current altitudinal range from 3200 to 4000 m) suggests the development of open, treeless, vegetation between 9.5 and 5.4 Ma, and highlight the presence of a high Andes in the late Miocene hinterland. Poaceae progressively increased from 9 Ma, with a notable rise from 4 Ma onwards, and percentages well above post-glacial and modern values, particularly between 2.6 and 0.8 Ma. We hypothesize that the rise of the grasses is a basin-wide phenomenon, but that the Plio-Pleistocene expansion of open, treeless vegetation on the Andean slopes and foothills are the main contributor. This rise in grasses was likely caused by climatic fluctuations, and subsequent changes in relief and erosion rates. We conclude that the onset of the Amazon River is coupled with Neogene Andean tectonism and that subsequent

Water resources of the Humboldt River Valley near Winnemucca, Nevada

USGS Publications Warehouse

Cohen, Philip M.

1965-01-01

This report, resulting from studies made by the U.S. Geological Survey as part of the interagency Humboldt River Research Project, describes the qualitative and quantitative relations among the components of the hydrologic system in the Winnemucca Reach of the Humboldt River valley. The area studied includes the segment of the Humboldt River valley between the Comus and Rose Creek gaging stations. It is almost entirely in Humboldt County in north-central Nevada, and is about 200 miles downstream from the headwaters of the Humboldt River. Agriculture is the major economic activity in the area. Inasmuch as the valley lowlands receive an average of about 8 inches of precipitation per year and because the rate of evaporation from free-water surfaces is about six times the average annual precipitation, all crops in the area (largely forage crops) are irrigated. About 85 percent of the cultivated land is irrigated with Humboldt River water; the remainder is irrigated from about 20 irrigation wells. The consolidated rocks of the uplifted fault-block mountains are largely barriers to the movement of ground water and form ground-water and surface-water divides. Unconsolidated deposits of late Tertiary and Quaternary age underlie the valley lowlands to a maximum depth of about 5,000 feet. These deposits are in hydraulic continuity with the Humboldt River and store and transmit most of the economically recoverable ground water. Included in the valley fill is a highly permeable sand and gravel deposit having a maximum thickness of about 90-100 feet; it underlies the flood plain and bordering terraces throughout most of the project area. This deposit is almost completely saturated and contains about 500,000 acre-feet of ground water in storage. The Humboldt River is the source of 90-95 percent of the surface-water inflow to the area. In water years 1949-62 the average annual streamflow at the Comus gaging station at the upstream margin of the area was 172,100 acre-feet; outflow

Drought in an invaded Hawaiian lowland wet forest

Treesearch

Jené Michaud; Susan Cordell; T. Colleen Cole; Rebecca Ostertag

2015-01-01

In this study we examined historic drought frequency and hydrologic effects of removing invasive plants from one of the few remaining Hawaiian wet lowland forests, near Hilo, Hawai‘i. We developed a conceptual and statistical model of Hilo droughts using historic rainfall and pan evaporation data and discovered that episodes of low soil moisture were most likely from...

Sharing the rivers: Balancing the needs of people and fish against the backdrop of heavy sediment loads downstream from Mount Rainier, Washington

NASA Astrophysics Data System (ADS)

Magirl, C. S.; Czuba, J. A.; Czuba, C. R.; Curran, C. A.

2012-12-01

Despite heavy sediment loads, large winter floods, and floodplain development, the rivers draining Mount Rainier, a 4,392-m glaciated stratovolcano within 85 km of sea level at Puget Sound, Washington, support important populations of anadromous salmonids, including Chinook salmon and steelhead trout, both listed as threatened under the Endangered Species Act. Aggressive river-management approaches of the early 20th century, such as bank armoring and gravel dredging, are being replaced by more ecologically sensitive approaches including setback levees. However, ongoing aggradation rates of up to 8 cm/yr in lowland reaches present acute challenges for resource managers tasked with ensuring flood protection without deleterious impacts to aquatic ecology. Using historical sediment-load data and a recent reservoir survey of sediment accumulation, rivers draining Mount Rainer were found to carry total sediment yields of 350 to 2,000 tonnes/km2/yr, notably larger than sediment yields of 50 to 200 tonnes/km2/yr typical for other Cascade Range rivers. An estimated 70 to 94% of the total sediment load in lowland reaches originates from the volcano. Looking toward the future, transport-capacity analyses and sediment-transport modeling suggest that large increases in bedload and associated aggradation will result from modest increases in rainfall and runoff that are predicted under future climate conditions. If large sediment loads and associated aggradation continue, creative solutions and long-term management strategies are required to protect people and structures in the floodplain downstream of Mount Rainier while preserving aquatic ecosystems.

Sediment‐associated organic matter sources and sediment oxygen demand in a Special Area of Conservation (SAC): A case study of the River Axe, UK

PubMed Central

Zhang, Y.; McMillan, S.; Dixon, E. R.; Stringfellow, A.; Bateman, S.; Sear, D. A.

2017-01-01

Abstract Oxygen demand in river substrates providing important habitats for the early life stages of aquatic ecology, including lithophilous fish, can arise due to the oxidation of sediment‐associated organic matter. Oxygen depletion associated with this component of river biogeochemical cycling, will, in part, depend on the sources of such material. A reconnaissance survey was therefore undertaken to assess the relative contributions from bed sediment‐associated organic matter sources potentially impacting on the River Axe Special Area of Conservation (SAC), in SW England. Source fingerprinting, including Monte Carlo uncertainty analysis, suggested that the relative frequency‐weighted average median source contributions ranged between 19% (uncertainty range 0–82%) and 64% (uncertainty range 0–99%) for farmyard manures or slurries, 4% (uncertainty range 0–49%) and 35% (uncertainty range 0–100%) for damaged road verges, 2% (uncertainty range 0–100%) and 68% (uncertainty range 0–100%) for decaying instream vegetation, and 2% (full uncertainty range 0–15%) and 6% (uncertainty range 0–48%) for human septic waste. A reconnaissance survey of sediment oxygen demand (SOD) along the channel designated as a SAC yielded a mean SOD5 of 4 mg O2 g−1 dry sediment and a corresponding SOD20 of 7 mg O2 g−1 dry sediment, compared with respective ranges of 1–15 and 2–30 mg O2 g−1 dry sediment, measured by the authors for a range of river types across the UK. The findings of the reconnaissance survey were used in an agency (SW region) catchment appraisal exercise for informing targeted management to help protect the SAC. PMID:29527135

Out of Amazonia again and again: episodic crossing of the Andes promotes diversification in a lowland forest flycatcher

PubMed Central

Miller, Matthew J; Bermingham, Eldredge; Klicka, John; Escalante, Patricia; do Amaral, Fabio S. Raposo; Weir, Jason T; Winker, Kevin

2008-01-01

Most Neotropical lowland forest taxa occur exclusively on one side of the Andes despite the availability of appropriate habitat on both sides. Almost all molecular phylogenies and phylogenetic analyses of species assemblages (i.e. area cladograms) have supported the hypothesis that Andean uplift during the Late Pliocene created a vicariant barrier affecting lowland lineages in the region. However, a few widespread plant and animal species occurring in lowland forests on both sides of the Andes challenge the generality of this hypothesis. To understand the role of the Andes in the history of such organisms, we reconstructed the phylogeographic history of a widespread Neotropical flycatcher (Mionectes oleagineus) in the context of the other four species in the genus. A molecular phylogeny based on nuclear and mitochondrial sequences unambiguously showed an early basal split between montane and lowland Mionectes. The phylogeographic reconstruction of lowland taxa revealed a complex history, with multiple cases in which geographically proximate populations do not represent sister lineages. Specifically, three populations of M. oleagineus west of the Andes do not comprise a monophyletic clade; instead, each represents an independent lineage with origins east of the Andes. Divergence time estimates suggest that at least two cross-Andean dispersal events post-date Andean uplift. PMID:18285279

Unravelling recent environmental change in a lowland river valley, eastern Ireland: geoarchaeological applications

NASA Astrophysics Data System (ADS)

Foster, Gez; Turner, Jonathan

2010-05-01

This paper reports the preliminary findings of an Irish Heritage Council INSTAR funded research project on the geoarchaeology and fluvial geomorphology of the lower River Boyne valley, eastern Ireland. The nature and evolution of the contemporary Boyne floodplain at Dunmoe, Co. Meath (53° 40' 22.8" N, 6° 37' 54.7" W) has been investigated using a multi-technique approach combining field and terrestrial LiDAR-based geomorphological mapping, radiocarbon dating of channel migration activity, electrical resistivity tomography surveys of sub-surface topography and high-resolution X-ray and XRF geochemical characterisation of fine-grained sediment fill sequences. All of these lines of evidence support a tripartite sub-division of the floodplain. Valley marginal floodplain Zone 1 is characterised by a colluvial sediment fill which has buried an irregular ditch-basin-platform surface containing recent archaeological material. Subtle variations in mapped elevation suggest that the buried surface may represent the site of an abandoned river-side complex, possibly a small docking area or port. Geomorphological field relationships suggest that the possible archaeological site was connected to a former bank line position of the main River Boyne (floodplain Zone 2) via a small canal. Radiocarbon dating of Zone 2 channel gravels suggests that the channel associated with this bank position was abandoned some time before 1490-1610 AD. Subsequent vertical and lateral channel migration, the onset of which has been radiocarbon dated to the 17th or 18th century AD, led to the development of the lowest and most recent floodplain surface (Zone 3). The sedimentology and geochemistry of the Zone 2 and 3 fluvial sediment sequences suggests that recent centuries have involved an increase in fluvial flood risk, evidenced by the burial of alluvial soils by bedded, shell-rich sands. A more complete understanding of the timing and environmental drivers of increasing flood risk is anticipated

The role of large wood in retaining fine sediment, organic matter and plant propagules in a small, single-thread forest river

NASA Astrophysics Data System (ADS)

Osei, Nana A.; Gurnell, Angela M.; Harvey, Gemma L.

2015-04-01

This paper investigates associations among large wood accumulations, retained sediment, and organic matter and the establishment of a viable propagule bank within a forested reach of a lowland river, the Highland Water, UK. A wood survey within the 2-km study reach, illustrates that the quantity of wood retained within the channel is typical of relatively unmanaged river channels bordered by deciduous woodland and that the wood accumulations (jams) that are present are well developed, typically spanning the river channel and comprised of wood that is well decayed. Sediment samples were obtained in a stratified random design focusing on nine subreaches within which samples were aggregated from five different types of sampling location. Two of these locations were wood-associated (within and on bank faces immediately adjacent to wood jams), and the other three locations represented the broader river environment (gravel bars, bank faces, floodplain). The samples were analysed to establish their calibre, organic, and viable plant propagule content. The gravel bar sampling locations retained significantly coarser sediment containing a lower proportion of organic matter and viable propagules than the other four sampling locations. The two wood-related sampling locations retained sediment of intermediate calibre between the gravel bar and the bank-floodplain samples but they retained significantly more organic matter and viable propagules than were found in the other three sampling locations. In particular, the jam bank samples (areas of sediment accumulation against bank faces adjacent to wood jams) contained the highest number of propagules and the largest number of propagule species. These results suggest that retention of propagules, organic matter and relatively fine sediment in and around wood jams has the potential to support vegetation regeneration, further sediment retention, and as a consequence, landform development within woodland streams, although this

Are lowland rainforests really evolutionary museums? Phylogeography of the green hylia (Hylia prasina) in the Afrotropics.

PubMed

Marks, Ben D

2010-04-01

A recent trend in the literature highlights the special role that tropical montane regions and habitat transitions peripheral to large blocks of lowland rainforest play in the diversification process. The emerging view is one of lowland rainforests as evolutionary 'museums'; where biotic diversity is maintained over evolutionary time, and additional diversity is accrued from peripheral areas, but where there has been little recent diversification. This leads to the prediction of genetic diversity without geographic structure in widespread taxa. Here, I assess the notion of the lowland rainforest 'museum' with a phylogeographic study of the green hylia (Aves: Sylviidae: Hylia prasina) using 1132 bp of mtDNA sequence data. The distribution of genetic diversity within the mainland subspecies of Hylia reveals five highly divergent haplotype groups distributed in accordance with broad-scale areas of endemism in the Afrotropics. This pattern of genetic diversity within a currently described subspecies refutes the characterization of lowland forests as evolutionary museums. If the pattern of geographic variation in Hylia occurs broadly in widespread rainforest species, conservation policy makers may need to rethink their priorities for conservation in the Afrotropics. (c) 2009 Elsevier Inc. All rights reserved.

Cerebral pressure–flow relationship in lowlanders and natives at high altitude

PubMed Central

Smirl, Jonathan D; Lucas, Samuel J E; Lewis, Nia C S; duManior, Gregory R; Smith, Kurt J; Bakker, Akke; Basnyat, Aperna S; Ainslie, Philip N

2014-01-01

We investigated if dynamic cerebral pressure–flow relationships in lowlanders are altered at high altitude (HA), differ in HA natives and after return to sea level (SL). Lowlanders were tested at SL (n=16), arrival to 5,050 m, after 2-week acclimatization (with and without end-tidal PO2 normalization), and upon SL return. High-altitude natives (n=16) were tested at 5,050 m. Testing sessions involved resting spontaneous and driven (squat–stand maneuvers at very low (VLF, 0.05 Hz) and low (LF, 0.10 Hz) frequencies) measures to maximize blood pressure (BP) variability and improve assessment of the pressure–flow relationship using transfer function analysis (TFA). Blood flow velocity was assessed in the middle (MCAv) and posterior (PCAv) cerebral arteries. Spontaneous VLF and LF phases were reduced and coherence was elevated with acclimatization to HA (P<0.05), indicating impaired pressure–flow coupling. However, when BP was driven, both the frequency- and time-domain metrics were unaltered and comparable with HA natives. Acute mountain sickness was unrelated to TFA metrics. In conclusion, the driven cerebral pressure–flow relationship (in both frequency and time domains) is unaltered at 5,050 m in lowlanders and HA natives. Our findings indicate that spontaneous changes in TFA metrics do not necessarily reflect physiologically important alterations in the capacity of the brain to regulate BP. PMID:24169852

Cerebral pressure-flow relationship in lowlanders and natives at high altitude.

PubMed

Smirl, Jonathan D; Lucas, Samuel J E; Lewis, Nia C S; duManoir, Gregory R; Dumanior, Gregory R; Smith, Kurt J; Bakker, Akke; Basnyat, Aperna S; Ainslie, Philip N

2014-02-01

We investigated if dynamic cerebral pressure-flow relationships in lowlanders are altered at high altitude (HA), differ in HA natives and after return to sea level (SL). Lowlanders were tested at SL (n=16), arrival to 5,050 m, after 2-week acclimatization (with and without end-tidal PO2 normalization), and upon SL return. High-altitude natives (n=16) were tested at 5,050 m. Testing sessions involved resting spontaneous and driven (squat-stand maneuvers at very low (VLF, 0.05 Hz) and low (LF, 0.10 Hz) frequencies) measures to maximize blood pressure (BP) variability and improve assessment of the pressure-flow relationship using transfer function analysis (TFA). Blood flow velocity was assessed in the middle (MCAv) and posterior (PCAv) cerebral arteries. Spontaneous VLF and LF phases were reduced and coherence was elevated with acclimatization to HA (P<0.05), indicating impaired pressure-flow coupling. However, when BP was driven, both the frequency- and time-domain metrics were unaltered and comparable with HA natives. Acute mountain sickness was unrelated to TFA metrics. In conclusion, the driven cerebral pressure-flow relationship (in both frequency and time domains) is unaltered at 5,050 m in lowlanders and HA natives. Our findings indicate that spontaneous changes in TFA metrics do not necessarily reflect physiologically important alterations in the capacity of the brain to regulate BP.

Analysis of river planforms in the New Madrid region and possible relations to tectonic warping across the loess bluffs and within the meander belt of the Mississippi River

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

Johnson, K.A.; Mayer, L.

1993-03-01

Stream channel planforms measured from such streams as the Hatchie (H), L'Anguille (LA), St. Francis, White (W) and Little Red (LR) rivers provide a way to study influences of topographic warping between the loess bluffs that bound the Mississippi river valley. Planforms are analyzed using sinuosity, Richardson analysis, and pattern. Pattern changes include transitions from braided to meandering and meandering to straight. Sinuosities of the W and LR rivers show a transition from low sinuosity, [1.3, 1.4] to higher sinuosity [2.6, 2.8], over a short distance, as they cross the bluffs from the uplands to the Western Lowlands. On themore » east, the Hatchie changes from a braided to meandering pattern upon crossing the bluffs. Its sinuosity varies from a low of about 1.4 to a high of 2.2, coincident with a marsh area. The LA river flows on the west side of Crowley's Ridge and is paralleled by the St. Francis river on the east. These rivers, with very different drainage areas and sinuosities, show matching meander bends at similar wavelengths along Crowley's Ridge. The bends are about 10 km in 1/2 wavelength suggesting some extraordinary influence on pattern perpendicular to the ridge. Richardson analysis indicates that features with a 1/2 wavelength of 2 km may control several rivers' bending patterns. These features are analyzed to determine their spatial relations with one another.« less

Ventricular structure, function, and mechanics at high altitude: chronic remodeling in Sherpa vs. short-term lowlander adaptation.

PubMed

Stembridge, Mike; Ainslie, Philip N; Hughes, Michael G; Stöhr, Eric J; Cotter, James D; Nio, Amanda Q X; Shave, Rob

2014-08-01

Short-term, high-altitude (HA) exposure raises pulmonary artery systolic pressure (PASP) and decreases left-ventricular (LV) volumes. However, relatively little is known of the long-term cardiac consequences of prolonged exposure in Sherpa, a highly adapted HA population. To investigate short-term adaptation and potential long-term cardiac remodeling, we studied ventricular structure and function in Sherpa at 5,050 m (n = 11; 31 ± 13 yr; mass 68 ± 10 kg; height 169 ± 6 cm) and lowlanders at sea level (SL) and following 10 ± 3 days at 5,050 m (n = 9; 34 ± 7 yr; mass 82 ± 10 kg; height 177 ± 6 cm) using conventional and speckle-tracking echocardiography. At HA, PASP was higher in Sherpa and lowlanders compared with lowlanders at SL (both P < 0.05). Sherpa had smaller right-ventricular (RV) and LV stroke volumes than lowlanders at SL with lower RV systolic strain (P < 0.05) but similar LV systolic mechanics. In contrast to LV systolic mechanics, LV diastolic, untwisting velocity was significantly lower in Sherpa compared with lowlanders at both SL and HA. After partial acclimatization, lowlanders demonstrated no change in the RV end-diastolic area; however, both RV strain and LV end-diastolic volume were reduced. In conclusion, short-term hypoxia induced a reduction in RV systolic function that was also evident in Sherpa following chronic exposure. We propose that this was consequent to a persistently higher PASP. In contrast to the RV, remodeling of LV volumes and normalization of systolic mechanics indicate structural and functional adaptation to HA. However, altered LV diastolic relaxation after chronic hypoxic exposure may reflect differential remodeling of systolic and diastolic LV function. Copyright © 2014 the American Physiological Society.

Ventricular structure, function, and mechanics at high altitude: chronic remodeling in Sherpa vs. short-term lowlander adaptation

PubMed Central

Ainslie, Philip N.; Hughes, Michael G.; Stöhr, Eric J.; Cotter, James D.; Nio, Amanda Q. X.; Shave, Rob

2014-01-01

Short-term, high-altitude (HA) exposure raises pulmonary artery systolic pressure (PASP) and decreases left-ventricular (LV) volumes. However, relatively little is known of the long-term cardiac consequences of prolonged exposure in Sherpa, a highly adapted HA population. To investigate short-term adaptation and potential long-term cardiac remodeling, we studied ventricular structure and function in Sherpa at 5,050 m (n = 11; 31 ± 13 yr; mass 68 ± 10 kg; height 169 ± 6 cm) and lowlanders at sea level (SL) and following 10 ± 3 days at 5,050 m (n = 9; 34 ± 7 yr; mass 82 ± 10 kg; height 177 ± 6 cm) using conventional and speckle-tracking echocardiography. At HA, PASP was higher in Sherpa and lowlanders compared with lowlanders at SL (both P < 0.05). Sherpa had smaller right-ventricular (RV) and LV stroke volumes than lowlanders at SL with lower RV systolic strain (P < 0.05) but similar LV systolic mechanics. In contrast to LV systolic mechanics, LV diastolic, untwisting velocity was significantly lower in Sherpa compared with lowlanders at both SL and HA. After partial acclimatization, lowlanders demonstrated no change in the RV end-diastolic area; however, both RV strain and LV end-diastolic volume were reduced. In conclusion, short-term hypoxia induced a reduction in RV systolic function that was also evident in Sherpa following chronic exposure. We propose that this was consequent to a persistently higher PASP. In contrast to the RV, remodeling of LV volumes and normalization of systolic mechanics indicate structural and functional adaptation to HA. However, altered LV diastolic relaxation after chronic hypoxic exposure may reflect differential remodeling of systolic and diastolic LV function. PMID:24876358

Climate change and the green energy paradox: the consequences for twaite shad Alosa fallax from the River Severn, U.K.

PubMed

Aprahamian, M W; Aprahamian, C D; Knights, A M

2010-11-01

A stock-recruitment model with a temperature component was used to estimate the effect of an increase in temperature predicted by climate change projections on population persistence and distribution of twaite shad Alosa fallax. An increase of 1 and 2° C above the current mean summer (June to August) water temperature of 17·8° C was estimated to result in a three and six-fold increase in the population, respectively. Climate change is also predicted to result in an earlier commencement to their spawning migration into fresh water. The model was expanded to investigate the effect of any additional mortality that might arise from a tidal power barrage across the Severn Estuary. Turbine mortality was separated into two components: (1) juvenile (pre-maturation) on their out migration during their first year and on their first return to the river to spawn and (2) post-maturation mortality on adults on the repeat spawning component of the population. Under current conditions, decreasing pre-maturation and post-maturation survival by 8% is estimated to result in the stock becoming extinct. It is estimated that an increase in mean summer water temperature of 1° C would mean that survival pre and post-maturation would need to be reduced by c. 10% before the stock becomes extinct. Therefore, climate change is likely to be beneficial to populations of A. fallax within U.K. rivers, increasing survival and thus, population persistence. © 2010 The Authors. Journal of Fish Biology © 2010 The Fisheries Society of the British Isles.

Natural hybrids and gene flow between upland and lowland switchgrass

USDA-ARS?s Scientific Manuscript database

Switchgrass (Panicum virgatum L.) is a perennial grass native to the North American tallgrass prairie and savanna habitats and is broadly adapted to the central and eastern USA. Upland and lowland ecotypes represent the two major taxa within switchgrass, which have distinct, but overlapping distribu...

An Indian Federation in Lowland Ecuador. IWGIA Document 28.

ERIC Educational Resources Information Center

Salazar, Ernesto

Official involvement of the Ecuadorian government with colonization of the southern lowlands, lands traditionally belonging to the Shuar Indians, began in the early 60's when the CREA (Centro de Reconversion Economica del Azuay) was created to provide assistance to white settlers. Until that time, the Shuar lands had been dominated by the Salesian…

Understanding the fluvial loss of carbon from the UK - implications for terrestrial carbon, greenhouse gases and water quality.

NASA Astrophysics Data System (ADS)

Worrall, F.; Howden, N. J. K.

2016-12-01

We have developed a number of methods to estimate the fate of fluvial organic matter through UK catchments. Here we include dissolved organic matter (DOM), particulate organic matter (POC), and dissolved gases to estimate losses from the terrestrial biosphere; in-stream losses and production (including the role of water and waste treatment); and export to the continental shelf and atmsophere. We use multiple approaches, including: mass balance studies, modelling and experimentation. Mass balance studies suggest that the UK terrestrial biosphere losses 5 Mtonnes C/yr (21.8 tonnes C/km2/yr) in the proportion of 7:22:4 (POC:DOC:diss. CO2). The mass balance studies suggest 3.5 Mtonnes C/yr (15.2 tonnes C/km2/yr) is lost to the atmosphere in the proportion 8:75:17 (POC:DOC:diss. CO2); UK rivers have short residence times (typically 1-2 days) and so the diurnal cycle becomes critical. Experiments show that turnover rates are close to zero overnight but that these can be periods of DOM production from turnover of POM and that the presence of POM may inhibit turnover of DOM; The development and modelling using physically-explicit rate laws showed that the loss of DOC was between 24 and 37% - lower than that estimated from mass balance studies, but that the loss rate of TOC (DOC + POC) was between 57 and 80% - close to that estimated from mass balance studies; The turnover of organic particles within rivers means that any notion that soil erosion leads to net carbon drawdown is entirely negated and the emission factor for gross soil erosion is estimated to be between 0.11 and 0.66 tonnes CO2eq/yr for every 1 tonne of gross erosion; and, Studies of molecular change of DOM and POM along rivers shows that, while POM represents an admixture of its sources (soils and vegetation), the DOM which enters rivers as highly oxidised becomes more reduced in channel. The release of greenhouse gases from UK rivers is now estimated to be between 15,800 - 33,000 ktonnes CO2eq/yr equivalent

Weed communities of rain-fed lowland rice vary with infestation by Rhamphicarpa fistulosa

NASA Astrophysics Data System (ADS)

Houngbédji, Tossimidé; Dessaint, Fabrice; Nicolardot, Bernard; Shykoff, Jacqui A.; Gibot-Leclerc, Stéphanie

2016-11-01

The facultative hemiparasitic plant Rhamphicarpa fistulosa (Orobanchaceae) thrives in seasonally wet soils in sub-Saharan Africa, mainly in marginal lowland rice growing environments where weeds are already a major constraint for rice production. Because lowland rice production is increasing in tropical Africa, it is important to ascertain the influence of R. fistulosa on weed plant communities in these rice-growing habitats. We investigated weed plant community richness and composition at four different levels of R. fistulosa infestation across two years of surveys from lowland rice fields in northern Togo (West Africa). Despite a lack of significant differences in community richness among sites with different R. fistulosa infestation levels, there were significant differences in community composition, both when estimated from presence-absence data and from relative abundance data, after controlling statistically for geographic proximity among sites. Rhamphicarpa fistulosa infestation, therefore, may influence the competitive balance between rice and its weeds and shape weed community structure. However, experimental studies are required to elucidate the weed host range of R. fistulosa and the direct and indirect effects of this hemiparasite in rice fields in order to predict its net impact on rice and its weed species.

Numerical modeling of incised-valley deposits in Tokyo lowland for the last 13 kyrs

NASA Astrophysics Data System (ADS)

Kubo, Y.; Syvitski, J. P.; Hutton, E. W.; Tanabe, S.

2006-12-01

A coupled-simulation by the hydrologic model HydroTrend and the stratigraphic model SedFlux is applied to the incised-valley-fill deposits in the Tokyo lowland for the last 13,000 years. The postglacial sediments supplied by paleo Tonegawa River have formed deltaic deposits controlled by eustatic sea-level rise after LGM. The effects of changes in sea level, climate, and morphology on the resultant architecture of the deposits are simulated and analyzed by the numerical models. Synthetic sediment flux from the paleo Tonegawa is computed by the hydrologic model HydroTrend. The model predicts variation in average rate of sediment production over geological time scale from changes in drainage area, precipitation, temperature and morphology. Random variation based on statistic climate data is added to the predicted average values to provide daily sediment discharge. The model prediction indicates that, despite 80% increase in drainage area in the past, competing effects of decreased precipitation resulted in relatively stable sediment discharge over the last 13,000 years. On the other hand, variation in daily sediment discharge shows drastic increase during infrequent storm events. Possible occurrence of hyperpycnal flows at the river mouth was indicated during such storms, which produced daily sediment load ten times larger than average yearly sediment discharge. The estimated sediment supply is used as input to the process-based forward-model 2D-SedFlux. SedFlux is able to simulate transport and deposition of sediments by such processes as river plume, bedload dumping and ocean storms with changing boundary conditions of sea level and basement morphology. The simulation is based on the initial paleo-morphology reconstructed from integrated core analysis from the area. 2D-SedFlux successfully predicts the formation of transgressive deposits and subsequent prograding delta deposits, and the results are comparable to general architecture of incised-valley fills in the

Flow reconstructions in the Upper Missouri River Basin using riparian tree rings

USGS Publications Warehouse

Schook, Derek M.; Friedman, Jonathan M.; Rathburn, Sara L.

2016-01-01

River flow reconstructions are typically developed using tree rings from montane conifers that cannot reflect flow regulation or hydrologic inputs from the lower portions of a watershed. Incorporating lowland riparian trees may improve the accuracy of flow reconstructions when these trees are physically linked to the alluvial water table. We used riparian plains cottonwoods (Populus deltoides ssp. monilifera) to reconstruct discharge for three neighboring rivers in the Upper Missouri River Basin: the Yellowstone (n = 389 tree cores), Powder (n = 408), and Little Missouri Rivers (n = 643). We used the Regional Curve Standardization approach to reconstruct log-transformed discharge over the 4 months in early summer that most highly correlated to tree ring growth. The reconstructions explained at least 57% of the variance in historical discharge and extended back to 1742, 1729, and 1643. These are the first flow reconstructions for the Lower Yellowstone and Powder Rivers, and they are the furthest downstream among Rocky Mountain rivers in the Missouri River Basin. Although mostly free-flowing, the Yellowstone and Powder Rivers experienced a shift from early-summer to late-summer flows within the last century. This shift is concurrent with increasing irrigation and reservoir storage, and it corresponds to decreased cottonwood growth. Low-frequency flow patterns revealed wet conditions from 1870 to 1980, a period that includes the majority of the historical record. The 1816–1823 and 1861–1865 droughts were more severe than any recorded, revealing that drought risks are underestimated when using the instrumental record alone.

Cultural Resources Mitigation at the McIlvaine Island Site (47Lc160) in Navigation Pool 7, Upper Mississippi River

DTIC Science & Technology

1989-03-01

site in 1986 by Debbie and Bill Bauman. The Baumans have since continued their support of understanding and preserving the cultural historical record...this region. For all of these efforts, we express our appreciation to Debbie and Bill. The Baumans were not alone in volunteering their time to assist...willow, silver maple, box elder, ash, elm, cottonwood, and river birch (Finley 1976). Curtis (1959:166) notes that the soils underlying such lowland

Benthic macroinvertebrates response to water management in a lowland river: effects of hydro-power vs irrigation off-stream diversions.

PubMed

Salmaso, Francesca; Crosa, Giuseppe; Espa, Paolo; Gentili, Gaetano; Quadroni, Silvia; Zaccara, Serena

2017-12-20

An eco-hydraulic survey of the highly regulated Adda River (northern Italy) was carried out to highlight the ecological implications of the current water management, including minimum flows (MFs) set as environmental protection measures. Macroinvertebrates, flows, and other main physico-chemical parameters were monitored from 2010 to 2012 at seven sites located in two river reaches characterized by different water abstraction schemes. In the upper part of the river, water is mainly diverted for hydro-power, and, in water-depleted reaches, discharges equalled MF for more than 100 days y -1 , mainly during winter. In the downstream river reach, where irrigation use prevails, discharges were on average three times higher than in the upper part of the river, and flow values similar to MF were detected only for short periods during summer. The two resulting streamflow patterns seem to have shaped different benthic communities, superimposing to the natural downstream variation. The upper reach is characterized by univoltine taxa, while the lower reach by multivoltine taxa adapted to a more disturbed environment. Chironomidae, a well-known tolerant benthic family, dominated at a site affected by point-source pollution, which turned out to be another determinant of macroinvertebrate community. Despite these differences among sites in the benthic community structure, the current water management seems to allow, for all of the investigated river sites, the achievement of the good ecological status as defined by the local law set in accomplishment of the Water Framework Directive.

Timing, frequency and environmental conditions associated with mainstem-tributary movement by a lowland river fish, golden perch (Macquaria ambigua).

PubMed

Koster, Wayne M; Dawson, David R; O'Mahony, Damien J; Moloney, Paul D; Crook, David A

2014-01-01

Tributary and mainstem connections represent important links for the movement of fish and other biota throughout river networks. We investigated the timing, frequency and environmental conditions associated with movements by adult golden perch (Macquaria ambigua) between the mainstem of the mid-Murray River and a tributary, the Goulburn River, in south-eastern Australia, using acoustic telemetry over four years (2007-2011). Fish were tagged and released in autumn 2007-2009 in the mid-Murray (n = 42) and lower Goulburn (n = 37) rivers within 3-6 km of the mid-Murray-lower Goulburn junction. 38% of tagged fish undertook mainstem-tributary movements, characterised mostly by temporary occupation followed by return of fish to the original capture river. Approximately 10% of tagged fish exhibited longer-term shifts between the mainstem and tributary. Movement of fish from the tributary into the mainstem occurred primarily during the spawning season and in some years coincided with the presence of golden perch eggs/larvae in drift samples in the mainstem. Many of the tributary-to-mainstem movements occurred during or soon after changes in flow. The movements of fish from the mainstem into the tributary were irregular and did not appear to be associated with spawning. The findings show that golden perch moved freely across the mainstem-tributary interface. This demonstrates the need to consider the spatial, behavioural and demographic interdependencies of aquatic fauna across geographic management units such as rivers.

Timing, Frequency and Environmental Conditions Associated with Mainstem–Tributary Movement by a Lowland River Fish, Golden Perch (Macquaria ambigua)

PubMed Central

Koster, Wayne M.; Dawson, David R.; O’Mahony, Damien J.; Moloney, Paul D.; Crook, David A.

2014-01-01

Tributary and mainstem connections represent important links for the movement of fish and other biota throughout river networks. We investigated the timing, frequency and environmental conditions associated with movements by adult golden perch (Macquaria ambigua) between the mainstem of the mid-Murray River and a tributary, the Goulburn River, in south-eastern Australia, using acoustic telemetry over four years (2007–2011). Fish were tagged and released in autumn 2007–2009 in the mid-Murray (n = 42) and lower Goulburn (n = 37) rivers within 3–6 km of the mid-Murray-lower Goulburn junction. 38% of tagged fish undertook mainstem–tributary movements, characterised mostly by temporary occupation followed by return of fish to the original capture river. Approximately 10% of tagged fish exhibited longer-term shifts between the mainstem and tributary. Movement of fish from the tributary into the mainstem occurred primarily during the spawning season and in some years coincided with the presence of golden perch eggs/larvae in drift samples in the mainstem. Many of the tributary-to-mainstem movements occurred during or soon after changes in flow. The movements of fish from the mainstem into the tributary were irregular and did not appear to be associated with spawning. The findings show that golden perch moved freely across the mainstem–tributary interface. This demonstrates the need to consider the spatial, behavioural and demographic interdependencies of aquatic fauna across geographic management units such as rivers. PMID:24788137

Retroperitoneal abscesses in two western lowland gorillas (Gorilla gorilla gorilla).

PubMed

Hahn, Alicia; D'Agostino, Jennifer; Cole, Gretchen A; Raines, Jan

2014-03-01

This report describes two cases of retroperitoneal abscesses in female western lowland gorillas (Gorilla gorilla gorilla). Clinical symptoms included perivulvar discharge, lameness, hindlimb paresis, and general malaise. Retroperitoneal abscesses should be considered as part of a complete differential list in female gorillas with similar clinical signs.

What is the prognosis of nitrogen losses from UK soils?

NASA Astrophysics Data System (ADS)

Burt, T. P.; Worrall, F.; Whelan, M.; Howden, N. J.

2009-12-01

The UK’s high population density, intensive agriculture and relative short, unimpeded rivers mean that the UK is a known “hotspot” of fluvial nitrogen flux. Furthermore, it is known that the fluvial flux of nitrogen from the UK is increasing. This study estimates the release of nitrate from the UK terrestrial biosphere to understand this rising fluvial flux and i to assess the in-stream losses of nitrate, thusgiving an assessment of the fluvial component of the total nitrogen budget of UK. The approach taken by the study is to use an export coefficient model coupled with a description of mineralisation and immobilisation of nitrogen within soil reserves. The study applies the modelling approach to the whole of the UK from 1925 to 2007 using long term records of: land use (including - agricultural, forestry and urban uses); livestock; human population and atmospheric deposition. The study shows that: i) The flux of nitrate from the UK soils varied from 420 to 1463 Ktonnes N/yr with two peaks in the period since 1925, one in 1944 and one in 1967, the first is caused by mineralisation of soil organic matter following large-scale land use change in the Second World War, and the second is a multifactorial response to land use change and intensification. ii) The current trend in the release from soils is downward whilst the current fluvial flux at the tidal limit is upwards. With the current trends fluvial flux at the tidal limit will be greater than release from the soils of the UK, i.e. there will be net gain across the fluvial network. This apparent gain can be explained by the breakthrough of high nitrate groundwater into surface waters.

Prediction of phosphorus loads in an artificially drained lowland catchment using a modified SWAT model

NASA Astrophysics Data System (ADS)

Bauwe, Andreas; Eckhardt, Kai-Uwe; Lennartz, Bernd

2017-04-01

Eutrophication is still one of the main environmental problems in the Baltic Sea. Currently, agricultural diffuse sources constitute the major portion of phosphorus (P) fluxes to the Baltic Sea and have to be reduced to achieve the HELCOM targets and improve the ecological status. Eco-hydrological models are suitable tools to identify sources of nutrients and possible measures aiming at reducing nutrient loads into surface waters. In this study, the Soil and Water Assessment Tool (SWAT) was applied to the Warnow river basin (3300 km2), the second largest watershed in Germany discharging into the Baltic Sea. The Warnow river basin is located in northeastern Germany and characterized by lowlands with a high proportion of artificially drained areas. The aim of this study were (i) to estimate P loadings for individual flow fractions (point sources, surface runoff, tile flow, groundwater flow), spatially distributed on sub-basin scale. Since the official version of SWAT does not allow for the modeling of P in tile drains, we tested (ii) two different approaches of simulating P in tile drains by changing the SWAT source code. The SWAT source code was modified so that (i) the soluble P concentration of the groundwater was transferred to the tile water and (ii) the soluble P in the soil was transferred to the tiles. The SWAT model was first calibrated (2002-2011) and validated (1992-2001) for stream flow at 7 headwater catchments at a daily time scale. Based on this, the stream flow at the outlet of the Warnow river basin was simulated. Performance statistics indicated at least satisfactory model results for each sub-basin. Breaking down the discharge into flow constituents, it becomes visible that stream flow is mainly governed by groundwater and tile flow. Due to the topographic situation with gentle slopes, surface runoff played only a minor role. Results further indicate that the prediction of soluble P loads was improved by the modified SWAT versions. Major sources of

Incised channel fills containing conifers indicate that seasonally dry vegetation dominated Pennsylvanian tropical lowlands

USGS Publications Warehouse

Falcon-Lang, H. J.; Nelson, W.J.; Elrick, S.; Looy, C.V.; Ames, P.R.; DiMichele, W.A.

2009-01-01

The idea that the Pennsylvanian tropical lowlands were temporally dominated by rainforest (i.e., the Coal Forest) is deeply ingrained in the literature. Here we challenge two centuries of research by suggesting that this concept is based on a taphonomic artifact, and that seasonally dry vegetation dominated instead. This controversial finding arises from the discovery of a new middle Pennsylvanian (Moscovian) fossil plant assemblage in southeast Illinois, United States. The assemblage, which contains xerophytic walchian conifers, occurs in channels incised into a calcic Vertisol below the Baker Coal. These plants grew on seasonally dry tropical lowlands inferred to have developed during a glacial phase. This xerophytic flora differs markedly from that of the typical clubmoss-dominated Coal Forest developed during deglaciation events. Although preserved only very rarely, we argue that such xerophytic floras were temporally as dominant, and perhaps more dominant, than the iconic Coal Forests, which are overrepresented in the fossil record due to taphonomic megabias. These findings require the iconography of Pennsylvanian tropical lowlands to be redrawn. ?? 2009 Geological Society of America.

Divergent biophysical controls of aquatic CO2 and CH4 in the World's two largest rivers.

PubMed

Borges, Alberto V; Abril, Gwenaël; Darchambeau, François; Teodoru, Cristian R; Deborde, Jonathan; Vidal, Luciana O; Lambert, Thibault; Bouillon, Steven

2015-10-23

Carbon emissions to the atmosphere from inland waters are globally significant and mainly occur at tropical latitudes. However, processes controlling the intensity of CO2 and CH4 emissions from tropical inland waters remain poorly understood. Here, we report a data-set of concurrent measurements of the partial pressure of CO2 (pCO2) and dissolved CH4 concentrations in the Amazon (n = 136) and the Congo (n = 280) Rivers. The pCO2 values in the Amazon mainstem were significantly higher than in the Congo, contrasting with CH4 concentrations that were higher in the Congo than in the Amazon. Large-scale patterns in pCO2 across different lowland tropical basins can be apprehended with a relatively simple statistical model related to the extent of wetlands within the basin, showing that, in addition to non-flooded vegetation, wetlands also contribute to CO2 in river channels. On the other hand, dynamics of dissolved CH4 in river channels are less straightforward to predict, and are related to the way hydrology modulates the connectivity between wetlands and river channels.

Ice-Sheet Glaciation of the Puget lowland, Washington, during the Vashon Stade (late pleistocene)

USGS Publications Warehouse

Thorson, R.M.

1980-01-01

During the Vashon Stade of the Fraser Glaciation, about 15,000-13,000 yr B.P., a lobe of the Cordilleran Ice Sheet occupied the Puget lowland of western Washington. At its maximum extent about 14,000 yr ago, the ice sheet extended across the Puget lowland between the Cascade Range and Olympic Mountains and terminated about 80 km south of Seattle. Meltwater streams drained southwest to the Pacific Ocean and built broad outwash trains south of the ice margin. Reconstructed longitudinal profiles for the Puget lobe at its maximum extent are similar to the modern profile of Malaspina Glacier, Alaska, suggesting that the ice sheet may have been in a near-equilibrium state at the glacial maximum. Progressive northward retreat from the terminal zone was accompanied by the development of ice-marginal streams and proglacial lakes that drained southward during initial retreat, but northward during late Vashon time. Relatively rapid retreat of the Juan de Fuca lobe may have contributed to partial stagnation of the northwestern part of the Puget lobe. Final destruction of the Puget lobe occurred when the ice retreated north of Admiralty Inlet. The sea entered the Puget lowland at this time, allowing the deposition of glacial-marine sediments which now occur as high as 50 m altitude. These deposits, together with ice-marginal meltwater channels presumed to have formed above sea level during deglaciation, suggest that a significant amount of postglacial isostatic and(or) tectonic deformation has occurred in the Puget lowland since deglaciation. ?? 1980.

Provenance of tetraether membrane lipids in a large temperate lake (Loch Lomond, UK): implications for GDGT-based palaeothermometry

NASA Astrophysics Data System (ADS)

Buckles, L. K.; Weijers, J. W. H.; Tran, X.-M.; Waldron, S.; Sinninghe Damsté, J. S.

2014-03-01

The application of glycerol dialkyl glycerol tetraether (GDGT)-based palaeoenvironmental proxies, such as the BIT index, TEX86 and the MBT/CBT palaeothermometer, has lately been expanded to lacustrine sediments. Given recent research identifying the production of branched, bacterial GDGTs (brGDGTs) within lakes, it is necessary to ascertain the effect of this lacustrine production on GDGT-based proxies. This study profiles a temperate, monomictic lake (Loch Lomond, UK), analysing labile intact polar GDGT lipids (IPLs) and resilient core GDGT lipids (CLs) in catchment soils, small tributary rivers, lake water and lake sediments. Loch Lomond consists of two basins bisected by the Highland Boundary Fault, resulting in a mesotrophic to oligotrophic gradient from south to north. The north basin is fjord-like, while the south basin is shallow with a lowland catchment. Besides abundant influxes of allochthonous soil and peat-derived (CL) brGDGTs, brGDGTs are produced in a variety of settings in Loch Lomond. Rather than integrating a scattered soil signal, there is some evidence that small rivers may contribute to the brGDGT pool through addition of brGDGTs produced in situ in these streams. 300 days of settling particles and water column profiles of suspended particulate matter (SPM; March and September 2011) reveal brGDGT production throughout the water column, with (IPL and CL) brGDGT distributions varying by basin. In lake sediments, in situ brGDGT production affects the distributions of sedimentary brGDGTs despite high soil and peat-derived organic matter influxes from the catchment. MBT/CBT-derived mean annual air temperature (MAAT) estimates from soil, river and lake sediments vary widely. A strong bias towards higher MAATs in the south and lower MAATs in the north basin further complicates the application of the proxy. These results emphasise that caution must be exercised when applying the MBT/CBT palaeothermometer to individual lakes in which the use of the proxy

Paleozoological Data Suggest Euroamerican Settlement Did Not Displace Ursids and North American Elk from Lowlands to Highlands

NASA Astrophysics Data System (ADS)

Lee Lyman, R.

2011-05-01

The hypothesis that Euroamerican settlement displaced some populations of large mammal taxa from lowland plains habitats to previously unoccupied highland mountain habitats was commonly believed in the late nineteenth and early twentieth centuries. By the middle twentieth century biologists had come to favor the hypothesis that Euroamerican colonization resulted in the extirpation of populations of large mammal in lowland habitats and those taxa survived in pre-existing relict populations in the highlands. Why modern biologists changed their minds is unclear. There is no historical evidence that unequivocally favors one hypothesis over the other. The low-elevation Columbia Basin of eastern Washington state in the northwestern United States is surrounded by forested mountains. The majority of historical records (1850 AD or younger) of black bear ( Ursus americanus), brown bear ( Ursus arctos), and North American elk ( Cervus elaphus) occur in mountainous, coniferous forest habitats. Paleozoological records of these taxa ≤ 10,000 year old and >160 year old in both highland and lowland habitats suggest the displacement hypothesis does not apply to ursids and elk in this area. These taxa seem to have been more or less ubiquitous in the area prior to Euroamerican colonization (ca. 1850 AD), and were extirpated from lowland habitats after colonization. Recent colonization of lowland shrub-steppe habitats by elk in particular, although historically unprecedented, must be categorized as recolonization rather than an invasion. Whether a species is classified as indigenous or nonindigenous may influence management activities focused on that species. The paleozoological record indicates ursids and elk are indigenous to the highland forest habitats of eastern Washington.

Cryptic diversity in Afro-tropical lowland forests: The systematics and biogeography of the avian genus Bleda.

PubMed

Huntley, Jerry W; Voelker, Gary

2016-06-01

Recent investigations of distributional patterns of Afro-tropical lowland forest species have demonstrated to some degree our overall lack of understanding involving historical diversification patterns. Traditionally, researchers have relied upon two hypotheses, each of which views the lowland forest of Africa in differing roles. The Pleistocene Forest Refuge Hypothesis (PFRH) posits that biogeographic patterns of avian lowland species are explained via allopatric speciation during forest fragmentation cycles in the Pleistocene epoch (c. 1.8Ma-11,700Ka). The Montane Speciation Hypothesis (MSH) countered by suggesting that lowland forests are "evolutionary museums" where species, which originally evolved in montane forest refuge centers, remained without further diversification. Furthermore, investigations have largely regarded widespread, avian species which lack phenotypic variability as biogeographically "uninformative", with regards to historical biogeographic patterns. To test the tenets of these ideas, we investigated the systematics and biogeography of the genus Bleda, whose constituent species are restricted to lowland forest and are lacking in phenotypic variation. Using extracted DNA from 179 individuals, we amplified two mitochondrial genes and three nuclear loci and utilized Bayesian phylogenetic methods and molecular clock dating to develop a time-calibrated phylogeny of Bleda. We used LaGrange to develop an ancestral area reconstruction for the genus. Haplotype networks for three species were generated using Network. We recovered the four currently recognized species of Bleda, plus a monophyletic B. ugandae, a current sub-species which may warrant full species status. We found that the origins of the genus Bleda are estimated to be in the Upper Guinean forests of West Africa, dating to the Miocene (c. 7.5Ma), while the speciation events for the rest of the genus are dated to the Pliocene (c. 5-1.8Ma). Our analyses recovered discrete and highly

The Importance of Bank Storage in Supplying Baseflow to Rivers Flowing Through Compartmentalized, Alluvial Aquifers

NASA Astrophysics Data System (ADS)

Rhodes, Kimberly A.; Proffitt, Tiffany; Rowley, Taylor; Knappett, Peter S. K.; Montiel, Daniel; Dimova, Natasha; Tebo, Daniel; Miller, Gretchen R.

2017-12-01

As water grows scarcer in semiarid and arid regions around the world, new tools are needed to quantify fluxes of water and chemicals between aquifers and rivers. In this study, we quantify the volumetric flux of subsurface water to a 24 km reach of the Brazos River, a lowland river that meanders through the Brazos River Alluvium Aquifer (BRAA), with 8 months of high-frequency differential gaging measurements using fixed gaging stations. Subsurface discharge sources were determined using natural tracers and End-Member Mixing Analysis (EMMA). During a 4 month river stage recession following a high stage event, subsurface discharge decreased from 50 m3/s to 0, releasing a total of 1.0 × 108 m3 of water. Subsurface discharge dried up even as the groundwater table at two locations in the BRAA located 300-500 m from the river remained ˜4 m higher than the river stage. Less than 4% of the water discharged from the subsurface during the prolonged recession period resembled the chemical fingerprint of the alluvial aquifer. Instead, the chemistry of this discharged water closely resembled high stage "event" river water. Together, these findings suggest that the river is well connected to rechargeable bank storage reservoirs but disconnected from the broader alluvial aquifer. The average width of discrete bank storage zones on each side of the river, identified with Electrical Resistivity Tomography (ERT), was approximately 1.5 km. In such highly compartmentalized aquifers, groundwater pumping is unlikely to impact the exchange between the river and the alluvium.

The Upper Mississippi River floodscape: spatial patterns of flood inundation and associated plant community distributions

USGS Publications Warehouse

DeJager, Nathan R.; Rohweder, Jason J.; Yin, Yao; Hoy, Erin E.

2016-01-01

Questions How is the distribution of different plant communities associated with patterns of flood inundation across a large floodplain landscape? Location Thirty-eight thousand nine hundred and seventy hectare of floodplain, spanning 320 km of the Upper Mississippi River (UMR). Methods High-resolution elevation data (Lidar) and 30 yr of daily river stage data were integrated to produce a ‘floodscape’ map of growing season flood inundation duration. The distributions of 16 different remotely sensed plant communities were quantified along the gradient of flood duration. Results Models fitted to the cumulative frequency of occurrence of different vegetation types as a function of flood duration showed that most types exist along a continuum of flood-related occurrence. The diversity of community types was greatest at high elevations (0–10 d of flooding), where both upland and lowland community types were found, as well as at very low elevations (70–180 d of flooding), where a variety of lowland herbaceous communities were found. Intermediate elevations (20–60 d of flooding) tended to be dominated by floodplain forest and had the lowest diversity of community types. Conclusions Although variation in flood inundation is often considered to be the main driver of spatial patterns in floodplain plant communities, few studies have quantified flood–vegetation relationships at broad scales. Our results can be used to identify targets for restoration of historical hydrological regimes or better anticipate hydro-ecological effects of climate change at broad scales.

Abundance and production of riparian trees in the lowland floodplain of the Queets River, Washington.

Treesearch

Estelle V. Balian; Robert J. Naiman

2005-01-01

Riparian zones associated with alluvial rivers are spatially dynamic, forming distinct vegetative mosaics that exhibit sharp contrasts in structure and processes related to the underlying biophysical template. The productivity of riparian plants, especially trees, influences streamside community characteristics as, well as the forms and fluxes of organic matter to...

Multiple stress response of lowland stream benthic macroinvertebrates depends on habitat type.

PubMed

Graeber, Daniel; Jensen, Tinna M; Rasmussen, Jes J; Riis, Tenna; Wiberg-Larsen, Peter; Baattrup-Pedersen, Annette

2017-12-01

Worldwide, lowland stream ecosystems are exposed to multiple anthropogenic stress due to the combination of water scarcity, eutrophication, and fine sedimentation. The understanding of the effects of such multiple stress on stream benthic macroinvertebrates has been growing in recent years. However, the interdependence of multiple stress and stream habitat characteristics has received little attention, although single stressor studies indicate that habitat characteristics may be decisive in shaping the macroinvertebrate response. We conducted an experiment in large outdoor flumes to assess the effects of low flow, fine sedimentation, and nutrient enrichment on the structure of the benthic macroinvertebrate community in riffle and run habitats of lowland streams. For most taxa, we found a negative effect of low flow on macroinvertebrate abundance in the riffle habitat, an effect which was mitigated by fine sedimentation for overall community composition and the dominant shredder species (Gammarus pulex) and by nutrient enrichment for the dominant grazer species (Baetis rhodani). In contrast, fine sediment in combination with low flow rapidly affected macroinvertebrate composition in the run habitat, with decreasing abundances of many species. We conclude that the effects of typical multiple stressor scenarios on lowland stream benthic macroinvertebrates are highly dependent on habitat conditions and that high habitat diversity needs to be given priority by stream managers to maximize the resilience of stream macroinvertebrate communities to multiple stress. Copyright © 2017 Elsevier B.V. All rights reserved.

Hydrology of inland tropical lowlands: the Kapuas and Mahakam wetlands

NASA Astrophysics Data System (ADS)

Hidayat, Hidayat; Teuling, Adriaan J.; Vermeulen, Bart; Taufik, Muh; Kastner, Karl; Geertsema, Tjitske J.; Bol, Dinja C. C.; Hoekman, Dirk H.; Sri Haryani, Gadis; Van Lanen, Henny A. J.; Delinom, Robert M.; Dijksma, Roel; Anshari, Gusti Z.; Ningsih, Nining S.; Uijlenhoet, Remko; Hoitink, Antonius J. F.

2017-05-01

Wetlands are important reservoirs of water, carbon and biodiversity. They are typical landscapes of lowland regions that have high potential for water retention. However, the hydrology of these wetlands in tropical regions is often studied in isolation from the processes taking place at the catchment scale. Our main objective is to study the hydrological dynamics of one of the largest tropical rainforest regions on an island using a combination of satellite remote sensing and novel observations from dedicated field campaigns. This contribution offers a comprehensive analysis of the hydrological dynamics of two neighbouring poorly gauged tropical basins; the Kapuas basin (98 700 km2) in West Kalimantan and the Mahakam basin (77 100 km2) in East Kalimantan, Indonesia. Both basins are characterised by vast areas of inland lowlands. Hereby, we put specific emphasis on key hydrological variables and indicators such as discharge and flood extent. The hydroclimatological data described herein were obtained during fieldwork campaigns carried out in the Kapuas over the period 2013-2015 and in the Mahakam over the period 2008-2010. Additionally, we used the Tropical Rainfall Measuring Mission (TRMM) rainfall estimates over the period 1998-2015 to analyse the distribution of rainfall and the influence of El-Niño - Southern Oscillation. Flood occurrence maps were obtained from the analysis of the Phase Array type L-band Synthetic Aperture Radar (PALSAR) images from 2007 to 2010. Drought events were derived from time series of simulated groundwater recharge using time series of TRMM rainfall estimates, potential evapotranspiration estimates and the threshold level approach. The Kapuas and the Mahakam lake regions are vast reservoirs of water of about 1000 and 1500 km2 that can store as much as 3 and 6.5 billion m3 of water, respectively. These storage capacity values can be doubled considering the area of flooding under vegetation cover. Discharge time series show that

Mars: the evolutionary history of the northern lowlands based on crater counting and geologic mapping

USGS Publications Warehouse

Werner, S.C.; Tanaka, K.L.; Skinner, J.A.

2011-01-01

The geologic history of planetary surfaces is most effectively determined by joining geologic mapping and crater counting which provides an iterative, qualitative and quantitative method for defining relative ages and absolute model ages. Based on this approach, we present spatial and temporal details regarding the evolution of the Martian northern plains and surrounding regions. The highland–lowland boundary (HLB) formed during the pre-Noachian and was subsequently modified through various processes. The Nepenthes Mensae unit along the northern margins of the cratered highlands, was formed by HLB scarp-erosion, deposition of sedimentary and volcanic materials, and dissection by surface runoff between 3.81 and 3.65 Ga. Ages for giant polygons in Utopia and Acidalia Planitiae are ~ 3.75 Ga and likely reflect the age of buried basement rocks. These buried lowland surfaces are comparable in age to those located closer to the HLB, where a much thinner, post-HLB deposit is mapped. The emplacement of the most extensive lowland surfaces ended between 3.75 and 3.4 Ga, based on densities of craters generally View the MathML source> 3 km in diameter. Results from the polygonal terrain support the existence of a major lowland depocenter shortly after the pre-Noachian formation of the northern lowlands. In general, northern plains surfaces show gradually younger ages at lower elevations, consistent local to regional unit emplacement and resurfacing between 3.6 and 2.6 Ga. Elevation levels and morphology are not necessarily related, and variations in ages within the mapped units are found, especially in units formed and modified by multiple geological processes. Regardless, most of the youngest units in the northern lowlands are considered to be lavas, polar ice, or thick mantle deposits, arguing against the ocean theory during the Amazonian Period (younger than about 3.15 Ga). All ages measured in the closest vicinity of the steep dichotomy escarpment are also 3.7 Ga or

Interspecific Relationships in Benthic Assemblages of a Large Lowland River : Co-existence or Competition as a Result of Habitat Characteristics

NASA Astrophysics Data System (ADS)

Akopian, M.; Usseglio-Polatera, P.

2005-05-01

Macrobenthic assemblages of the lower, regulated and canalized Marne River (France) are dominated by several "exotic", recently introduced species. Arrival, installation and spread of such alien species were certainly promoted by (1) the close connection between French and other European river systems (Rhine, Danube), (2) the modification of natural river flow and benthic habitats. Both habitat characteristics (e.g. granulometric composition, organic content) and corresponding benthic assemblage structure were analysed to identify the substrate affinity of major taxa in the lower Marne River. The main aim of the study was to evaluate the possible biotic interactions (i.e. competition for food and/or space) among dominant taxa as function of habitat features and to predict the future development of newly established species, already known as potential invaders: Corbicula fluminea (Bivalvia), Hypania invalida (Polychaeta), Chelicorophium curvispinum (Amphipoda), etc. Most of the newly established species, coming from the same biogeographical area ("invasional meltdown" hypothesis?), are eurytopic, with high fecundity and large food spectrum. First results demonstrated the co-existence of such species in the Marne River. But the future ecological importance of these organisms in benthic assemblages of the river depends on their present population size, population dynamics, and ability to colonize bottom substrates.

Phenology changes in the mayfly Ephemera danica in response to water temperature variations in the River Dove, UK

NASA Astrophysics Data System (ADS)

Johnson, Matthew; Everall, Nicholas; Wilby, Robert

2015-04-01

Water temperature in rivers is critical to aquatic life. Climate and environmental change can elevate river temperatures to levels that stress fish, but impacts on other aquatic organisms are not well understood. In particular, rising temperatures are expected to alter the phenology of aquatic insects at levels substantially below those required to stress fish species. The phenology of the mayfly Ephemera danica, a large burrowing species that is widespread throughout Europe, is known to be sensitive to temperature change. To assess the temporal and spatial variability in mayfly emergence, E. danica were monitored at two reaches in the River Dove, English Peak District over the period 2007 to 2013. Variations in Growing Degree Days (GDDs) were modelled for an upstream site with an annual temperature range in excess of 15 ° C (Beresford Dale) and a downstream site, dominated by near constant discharges of cool groundwater with an annual range less than 8 ° C (Dovedale). The emergence of E. danica was strongly related to GDDs at each site. E. danica usually remains in an aquatic larval stage for two years before emerging in its adult, terrestrial form. However, after particularly warm summers in Beresford Dale, E. danica was recorded to emerge after only one year in its aquatic form. Following the particularly wet/cold year of 2012, E. danica began to revert back to a bi-annual cycle. In Dovedale, an average of 374 fewer GDDs were accumulated in comparison to Beresford Dale. As a result, E. danica maintained a two-year growth cycle throughout the monitoring period despite the phenology changes observed 8 km upstream at Beresford. Changes to insect phenology are significant because populations with a one-year cycle are potentially more vulnerable to adverse weather when the majority of the population is in terrestrial form. Also, altering the growth, development and size of insects affects reproductive success with implications for population dynamics. Data from the

Hyperspectral remote sensing of canopy biodiversity in Hawaiian lowland rainforests

Treesearch

Kimberly M. Carlson; Gregory P. Asner; R. Flint Hughes; Rebecca Ostertag; Roberta E. Martin

2007-01-01

Mapping biological diversity is a high priority for conservation research, management and policy development, but few studies have provided diversity data at high spatial resolution from remote sensing. We used airborne imaging spectroscopy to map woody vascular plant species richness in lowland tropical forest ecosystems in Hawaii. Hyperspectral signatures spanning...

A long pollen record from lowland Amazonia: Forest and cooling in glacial times

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

Colinvaux, P.A.; Moreno, J.E.; Bush, M.B.

A continuous pollen history of more than 40,000 years was obtained from a lake in the lowland Amazon rain forest. Pollen spectra demonstrate that tropical rain forest occupied the region continuously and that savannas or grasslands were not present during the last glacial maximum. The data suggest that the western Amazon forest was not fragmented into refugia in glacial times and that the lowlands were not a source of dust. Glacial age forests were comparable to modern forests but also included species now restricted to higher evaluations by temperature, suggesting a cooling of the order of 5{degrees} to 6{degrees}C. 23more » refs., 22 tabs.« less

DIC transport in "flashy" streams - constraints from time series ionic- and δ13C data from the Manoa River (Hawaii)

NASA Astrophysics Data System (ADS)

Hagedorn, B.

2016-12-01

Hawaiian streams are flashy in nature because watersheds are small and steep and receive intense and unevenly distributed rainfall. As a result, stream chemistry is characterized by considerable spatiotemporal variability. To examine how rainfall and streamflow affect the solute content of the Manoa River in Hawaii, time-series geochemical data collected during 17 sampling campaigns in spring-fall of 2010 were evaluated in a coupled δ13CDIC/major ion inversion model. Spatially, the stream is characterized by a distinct shift from a low HCO3 (43 mg/L), low pCO2 (3,760 ppmv) and heavy δ13CDIC (-6.5‰) fingerprint in the upper reaches to a high HCO3 (91 mg/L), high pCO2 (8,961 ppmv) and light δ13CDIC (-11.7‰) signature in the lowlands. These trends are attributed to (1) progressive weathering of exposed aluminosilicates, and (2) downstream enrichment in CO2 from organic matter decay in the soil zone. Solute (i.e., nitrate) yields from nitric acid weathering are generally low (<1% of TDS), even in the developed lowlands, where runoff of nitrate and ammonium-enriched urban effluent has historically been documented. Data furthermore indicate a significant positive correlation between δ13CDIC and rainfall rates in the mid-stream section of the river which is consistent with an atmospheric CO2 dilution effect during high rainfall events. This dilution effect needs to be accounted for to reliably describe the role of volcanic island river systems in global assessments of CO2 consumption via silicate weathering and CO2 degassing.

Sediment deposition rate in the Falefa River basin, Upolu Island, Samoa.

PubMed

Terry, James P; Kostaschuk, Ray A; Garimella, Sitaram

2006-01-01

The (137)Cs method was employed to investigate the recent historical rate of sediment deposition on a lowland alluvial floodplain in the Falefa River basin, Upolu Island, Samoa. Caesium stratigraphy in the floodplain sediment profile was clearly defined, with a broad peak at 145-175 cm depth. The measured rate of vertical accretion over the last 40 years is 4.0+/-0.4 cm per year. This rate exceeds observations in humid environments elsewhere, but is similar to that recorded on other tropical Pacific Islands. Available flow data for the Vaisigano River in Samoa give a 'near-catastrophic' index value of 0.6 for flood variability. This is associated with the occurrence of tropical cyclones and storms in the Samoa area. Large floods therefore probably contribute to the high rate of floodplain sedimentation on Upolu Island. A small but growing body of evidence suggests that fluvial sedimentation rates on tropical Pacific islands are some of the highest in the world.

Quantifying habitat benefits of channel reconfigurations on a highly regulated river system, Lower Missouri River, USA

USGS Publications Warehouse

Erwin, Susannah O.; Jacobson, Robert B.; Elliott, Caroline M.

2017-01-01

We present a quantitative analysis of habitat availability in a highly regulated lowland river, comparing a restored reach with two reference reaches: an un-restored, channelized reach, and a least-altered reach. We evaluate the effects of channel modifications in terms of distributions of depth and velocity as well as distributions and availability of habitats thought to be supportive of an endangered fish, the pallid sturgeon (Scaphirhynchus albus). It has been hypothesized that hydraulic conditions that support food production and foraging may limit growth and survival of juvenile pallid sturgeon. To evaluate conditions that support these habitats, we constructed two-dimensional hydrodynamic models for the three study reaches, two located in the Lower Missouri River (channelized and restored reaches) and one in the Yellowstone River (least-altered reach). Comparability among the reaches was improved by scaling by bankfull discharge and bankfull channel area. The analysis shows that construction of side-channel chutes and increased floodplain connectivity increase the availability of foraging habitat, resulting in a system that is more similar to the reference reach on the Yellowstone River. The availability of food-producing habitat is low in all reaches at flows less than bankfull, but the two reaches in the Lower Missouri River – channelized and restored – display a threshold-like response as flows overtop channel banks, reflecting the persistent effects of channelization on hydraulics in the main channel. These high lateral gradients result in punctuated ecological events corresponding to flows in excess of bankfull discharge. This threshold effect in the restored reach remains distinct from that of the least-altered reference reach, where hydraulic changes are less abrupt and overbank flows more gradually inundate the adjacent floodplain. The habitat curves observed in the reference reach on the Yellowstone River may not be attainable within the

Ophthalmic examination of the captive western lowland gorilla (Gorilla gorilla gorilla).

PubMed

Liang, David; Alvarado, Thomas P; Oral, Deniz; Vargas, Jose M; Denena, Melissa M; McCulley, James P

2005-09-01

This study examined the captive western lowland gorilla (Gorilla gorilla gorilla) eye as compared and contrasted with the human eye. Bilateral ophthalmic examinations of western lowland gorillas (n = 5) while under general anesthesia were performed opportunistically, including slit-lamp biomicroscopy, dilated fundus examination, cycloplegic retinoscopy, Schiotz tonometry, corneal diameter and thickness measurements, A-scan and B-scan ultrasonography, keratometry, and cultures of the eyelid margins and bulbar conjunctiva. Mean spherical equivalent refractive error by cycloplegic retinoscopy was +1.20 +/- 0.59 diopters. Mean intraocular pressure by Schiotz tonometry was 12.0 +/- 4.3 mm Hg. Mean optic nerve head cup to disc ratio was 0.42 +/- 0.11. Mean horizontal corneal diameter was 13.4 +/- 0.8 mm, and mean vertical cornea diameter was 12.7 +/- 0.8 mm. Mean central corneal thickness by ultrasound pachymetry was 489 +/- 52 microm. Mean axial length of the eye by A-scan was 22.75 +/- 0.71 mm. Mean lens thickness by A-scan was 4.23 +/- 0.34 mm. Mean anterior chamber depth by A-scan was 4.00 +/- 0.26 mm. Mean keratometry reading was 44.38 +/- 1.64 diopters. Eyelid margin and bulbar conjunctival cultures isolated Candida sp. (n = 5), Staphylococcus aureus (n = 4), Staphylococcus epidermidis (n = 3), Staphylococcus saccharolyticus (n = 3), and Micrococcus sp. (n = 3). This study suggests important similarities between western lowland gorilla and human eyes. These similarities may allow diagnostics, techniques, and equipment for human eye surgery, such as those used for cataract extraction and intraocular lens implantation, to be successfully utilized for gorillas.

The effect of climate policy on the impacts of climate change on river flows in the UK

NASA Astrophysics Data System (ADS)

Arnell, Nigel W.; Charlton, Matthew B.; Lowe, Jason A.

2014-03-01

This paper compares the effects of two indicative climate mitigation policies on river flows in six catchments in the UK with two scenarios representing un-mitigated emissions. It considers the consequences of uncertainty in both the pattern of catchment climate change as represented by different climate models and hydrological model parameterisation on the effects of mitigation policy. Mitigation policy has little effect on estimated flow magnitudes in 2030. By 2050 a mitigation policy which achieves a 2 °C temperature rise target reduces impacts on low flows by 20-25% compared to a business-as-usual emissions scenario which increases temperatures by 4 °C by the end of the 21st century, but this is small compared to the range in impacts between different climate model scenarios. However, the analysis also demonstrates that an early peak in emissions would reduce impacts by 40-60% by 2080 (compared with the 4 °C pathway), easing the adaptation challenge over the long term, and can delay by several decades the impacts that would be experienced from around 2050 in the absence of policy. The estimated proportion of impacts avoided varies between climate model patterns and, to a lesser extent, hydrological model parameterisations, due to variations in the projected shape of the relationship between climate forcing and hydrological response.

Phytoplankton chlorophyte structure as related to ENSO events in a saline lowland river (Salado River, Buenos Aires, Argentina)

PubMed Central

Solari, Lía C; Gabellone, Néstor A; Claps, María C; Casco, María A; Quaíni, Karina P; Neschuk, Nancy C

2014-01-01

We analyzed the phytoplankton present in the lower sector of the Salado River (Buenos Aires, Argentina) for 10 years (1995–2005) and detected significant changes occurring in chlorophyte abundance and species richness during La Niña event (1998–1999), which period was analyzed throughout the entire basin (main stream and tributaries). We compared the physicochemical and biologic variables between two El Niño–La Niña–Southern Oscillation (ENSO) periods – El Niño (March 1997–January 1998) and La Niña (May 1998–May 1999) – to identify possible indicators of a relationship between climatic anomalies and chlorophyte performance. Chlorophyte density increased during the La Niña. Under normal or extreme hydrologic conditions, mobile (Chlamydomonas spp.) and nonmobile (Monoraphidium spp.) chlorophytes codominated. These species belonged to Reynolds's functional groups X1 and X2, those typical of nutrient-enriched environments. Comparative analyses between El Niño and La Niña periods indicated significant differences in physicochemical (K+, dissolved polyphenols, particulate reactive phosphorus, alkalinity, pH) and biologic (species diversity and richness, phytoplankton and chlorophyte total densities) variables between the two periods at all basin sites. During the La Niña condition, species richness was greater owing to interconnected shallow lakes and drainage-channel inputs, while the Shannon diversity index was lower because of the high abundance values of Monoraphidium minutum. A detailed analysis of the chlorophytes in the entire basin, indicated that changes in density and species dominance occurred on a regional scale although diverse chlorophyte assemblages were identified in the different sectors of the Salado River basin. After La Niña event, the entire basin had the potential to revert to the previous density values, showing the resilience to global environmental changes and the ability to reestablish the general conditions of

Phytoplankton chlorophyte structure as related to ENSO events in a saline lowland river (Salado River, Buenos Aires, Argentina).

PubMed

Solari, Lía C; Gabellone, Néstor A; Claps, María C; Casco, María A; Quaíni, Karina P; Neschuk, Nancy C

2014-04-01

We analyzed the phytoplankton present in the lower sector of the Salado River (Buenos Aires, Argentina) for 10 years (1995-2005) and detected significant changes occurring in chlorophyte abundance and species richness during La Niña event (1998-1999), which period was analyzed throughout the entire basin (main stream and tributaries). We compared the physicochemical and biologic variables between two El Niño-La Niña-Southern Oscillation (ENSO) periods - El Niño (March 1997-January 1998) and La Niña (May 1998-May 1999) - to identify possible indicators of a relationship between climatic anomalies and chlorophyte performance. Chlorophyte density increased during the La Niña. Under normal or extreme hydrologic conditions, mobile (Chlamydomonas spp.) and nonmobile (Monoraphidium spp.) chlorophytes codominated. These species belonged to Reynolds's functional groups X1 and X2, those typical of nutrient-enriched environments. Comparative analyses between El Niño and La Niña periods indicated significant differences in physicochemical (K(+), dissolved polyphenols, particulate reactive phosphorus, alkalinity, pH) and biologic (species diversity and richness, phytoplankton and chlorophyte total densities) variables between the two periods at all basin sites. During the La Niña condition, species richness was greater owing to interconnected shallow lakes and drainage-channel inputs, while the Shannon diversity index was lower because of the high abundance values of Monoraphidium minutum. A detailed analysis of the chlorophytes in the entire basin, indicated that changes in density and species dominance occurred on a regional scale although diverse chlorophyte assemblages were identified in the different sectors of the Salado River basin. After La Niña event, the entire basin had the potential to revert to the previous density values, showing the resilience to global environmental changes and the ability to reestablish the general conditions of stability.

UK Environmental Prediction - integration and evaluation at the convective scale

NASA Astrophysics Data System (ADS)

Lewis, Huw; Brunet, Gilbert; Harris, Chris; Best, Martin; Saulter, Andrew; Holt, Jason; Bricheno, Lucy; Brerton, Ashley; Reynard, Nick; Blyth, Eleanor; Martinez de la Torre, Alberto

2015-04-01

It has long been understood that accurate prediction and warning of the impacts of severe weather requires an integrated approach to forecasting. This was well demonstrated in the UK throughout winter 2013/14 when an exceptional run of severe winter storms, often with damaging high winds and intense rainfall led to significant damage from the large waves and storm surge along coastlines, and from saturated soils, high river flows and significant flooding inland. The substantial impacts on individuals, businesses and infrastructure indicate a pressing need to understand better the value that might be delivered through more integrated environmental prediction. To address this need, the Met Office, Centre for Ecology & Hydrology and National Oceanography Centre have begun to develop the foundations of a coupled high resolution probabilistic forecast system for the UK at km-scale. This links together existing model components of the atmosphere, coastal ocean, land surface and hydrology. Our initial focus on a 2-year Prototype project will demonstrate the UK coupled prediction concept in research mode, including an analysis of the winter 2013/14 storms and its impacts. By linking science development to operational collaborations such as the UK Natural Hazards Partnership, we can ensure that science priorities are rooted in user requirements. This presentation will provide an overview of UK environmental prediction activities and an update on progress during the first year of the Prototype project. We will present initial results from the coupled model development and discuss the challenges to realise the potential of integrated regional coupled forecasting for improving predictions and applications.

A paired-watershed budget study to quantify interbasin groundwater flow in a lowland rain forest, Costa Rica

NASA Astrophysics Data System (ADS)

Genereux, David P.; Jordan, Michael T.; Carbonell, David

2005-04-01

A paired-watershed budget study was used to quantify the annual water and major ion (sodium, potassium, magnesium, calcium, chloride, and sulfate) budgets of two adjacent lowland rain forest watersheds in Costa Rica. Interbasin groundwater flow (IGF) accounted for about two thirds of the water input and about 97% of the solute input (an average over the six major ions) to one watershed but little or none of the inputs to the adjacent watershed in which IGF was at most marginally distinguishable from zero. Results underscore the significance of IGF as a potential control on the hydrology and water quality of lowland watersheds, the spatial complexity of its occurrence in lowlands (where its influence may range from dominating to negligible on adjacent watersheds), and the importance of accounting for IGF in the design and execution of watershed studies and in water management.

Yellow fever: ecology, epidemiology, and role in the collapse of the Classic lowland Maya civilization.

PubMed

Wilkinson, R L

1995-07-01

Mystery has long surrounded the collapse of the Classic lowland Mayan civilization of the Peten region in Guatemala. Recent population reconstructions derived from archaeological evidence from the central lowlands show population declines from urban levels of between 2.5 and 3.5 million to around 536,000 in the two hundred year interval between 800 A.D. and 1000 A.D., the period known as the Classic Maya Collapse. A steady, but lesser rate of population decline continued until the time of European contact. When knowledge of the ecology and epidemiology of yellow fever and its known mosquito vectors are compared with what is known of the ecological conditions of lowland Guatemala as modified by the Classic Maya, provocative similarities are observed. When infection and mortality patterns of more recent urban yellow fever epidemics are used as models for a possible series of Classic Maya epidemics, a correlation is noted between the modeled rate of population decline for a series of epidemics, and population decline figures reconstructed from archaeological evidence.

Seasat synthetic aperture radar /SAR/ response to lowland vegetation types in eastern Maryland and Virginia

NASA Technical Reports Server (NTRS)

Krohn, M. D.; Milton, N. M.; Segal, D. B.

1983-01-01

Examination of Seasat SAR images of eastern Maryland and Virginia reveals botanical distinctions between vegetated lowland areas and adjacent upland areas. Radar returns from the lowland areas can be either brighter or darker than returns from the upland forests. Scattering models and scatterometer measurements predict an increase of 6 dB in backscatter from vegetation over standing water. This agrees with the 30-digital number (DN) increase observed in the digital Seasat data. The brightest areas in the Chickahominy, Virginia, drainage, containing P. virginica about 0.4 m high, contrast with the brightest areas in the Blackwater, Maryland, marshes, which contain mature loblolly pine in standing water. The darkest vegetated area in the Chickahominy drainage contains a forest of Nyssa aquatica (water tupelo) about 18 m high, while the darkest vegetated area in the Blackwater marshes contains the marsh plant Spartina alterniflora, 0.3 m high. The density, morphology, and relative geometry of the lowland vegetation with respect to standing water can all affect the strength of the return L band signal.

Simulating Forest Dynamics of Lowland Rainforests in Eastern Madagascar

NASA Technical Reports Server (NTRS)

Armstrong, Amanda; Fischer, Rico; Huth, Andreas; Shugart, Herman; Fatoyinbo, Temilola

2018-01-01

Ecological modeling and forecasting are essential tools for the understanding of complex vegetation dynamics. The parametric demands of some of these models are often lacking or scant for threatened ecosystems, particularly in diverse tropical ecosystems. One such ecosystem and also one of the world's biodiversity hotspots, Madagascar's lowland rainforests, have disappeared at an alarming rate. The processes that drive tree species growth and distribution remain as poorly understood as the species themselves. We investigated the application of the process-based individual-based FORMIND model to successfully simulate a Madagascar lowland rainforest using previously collected multi-year forest inventory plot data. We inspected the model's ability to characterize growth and species abundance distributions over the study site, and then validated the model with an independently collected forest-inventory dataset from another lowland rainforest in eastern Madagascar. Following a comparative analysis using inventory data from the two study sites, we found that FORMIND accurately captures the structure and biomass of the study forest, with r(squared) values of 0.976, 0.895, and 0.995 for 1:1 lines comparing observed and simulated values across all plant functional types for aboveground biomass (tonnes/ha), stem numbers, and basal area (m(squared)/ha), respectively. Further, in validation with a second study forest site, FORMIND also compared well, only slightly over-estimating shade-intermediate species as compared to the study site, and slightly under-representing shade-tolerant species in percentage of total aboveground biomass. As an important application of the FORMIND model, we measured the net ecosystem exchange (NEE, in tons of carbon per hectare per year) for 50 ha of simulated forest over a 1000-year run from bare ground. We found that NEE values ranged between 1 and -1 t Cha(exp -1)year(exp -1), consequently the study forest can be considered as a net neutral or

Channel-conveyance capacity, channel change, and sediment transport in the lower Puyallup, White, and Carbon Rivers, western Washington

USGS Publications Warehouse

Czuba, Jonathan A.; Czuba, Christiana R.; Magirl, Chistopher S.; Voss, Frank D.

2010-01-01

Draining the volcanic, glaciated terrain of Mount Rainier, Washington, the Puyallup, White, and Carbon Rivers convey copious volumes of water and sediment down to Commencement Bay in Puget Sound. Recent flooding in the lowland river system has renewed interest in understanding sediment transport and its effects on flow conveyance throughout the lower drainage basin. Bathymetric and topographic data for 156 cross sections were surveyed in the lower Puyallup River system by the U.S. Geological Survey (USGS) and were compared with similar datasets collected in 1984. Regions of significant aggradation were measured along the Puyallup and White Rivers. Between 1984 and 2009, aggradation totals as measured by changes in average channel elevation were as much as 7.5, 6.5, and 2 feet on the Puyallup, White, and Carbon Rivers, respectively. These aggrading river sections correlated with decreasing slopes in riverbeds where the rivers exit relatively confined sections in the upper drainage and enter the relatively unconstricted valleys of the low-gradient Puget Lowland. Measured grain-size distributions from each riverbed showed a progressive fining downstream. Analysis of stage-discharge relations at streamflow-gaging stations along rivers draining Mount Rainier demonstrated the dynamic nature of channel morphology on river courses influenced by glaciated, volcanic terrain. The greatest rates of aggradation since the 1980s were in the Nisqually River near National (5.0 inches per year) and the White River near Auburn (1.8 inches per year). Less pronounced aggradation was measured on the Puyallup River and the White River just downstream of Mud Mountain Dam. The largest measured rate of incision was measured in the Cowlitz River at Packwood (5.0 inches per year). Channel-conveyance capacity estimated using a one-dimensional hydraulic model decreased in some river reaches since 1984. The reach exhibiting the largest decrease (about 20-50 percent) in channel

Seasonal nutrient dynamics in a chalk stream: the River Frome, Dorset, UK.

PubMed

Bowes, M J; Leach, D V; House, W A

2005-01-05

Chalk streams provide unique, environmentally important habitats, but are particularly susceptible to human activities, such as water abstraction, fish farming and intensive agricultural activity on their fertile flood-meadows, resulting in increased nutrient concentrations. Weekly phosphorus, nitrate, dissolved silicon, chloride and flow measurements were made at nine sites along a 32 km stretch of the River Frome and its tributaries, over a 15 month period. The stretch was divided into two sections (termed the middle and lower reach) and mass balances were calculated for each determinand by totalling the inputs from upstream, tributaries, sewage treatment works and an estimate of groundwater input, and subtracting this from the load exported from each reach. Phosphorus and nitrate were retained within the river channel during the summer months, due to bioaccumulation into river biota and adsorption of phosphorus to bed sediments. During the autumn to spring periods, there was a net export, attributed to increased diffuse inputs from the catchment during storms, decomposition of channel biomass and remobilisation of phosphorus from the bed sediment. This seasonality of retention and remobilisation was higher in the lower reach than the middle reach, which was attributed to downstream changes in land use and fine sediment availability. Silicon showed much less seasonality, but did have periods of rapid retention in spring, due to diatom uptake within the river channel, and a subsequent release from the bed sediments during storm events. Chloride did not produce a seasonal pattern, indicating that the observed phosphorus and nitrate seasonality was a product of annual variation in diffuse inputs and internal riverine processes, rather than an artefact of sampling, flow gauging and analytical errors.

Surgical extractions for periodontal disease in a Western Lowland gorilla.

PubMed

Huff, John F

2010-01-01

This case report describes surgical exraction of multiple premolar and molar teeth in a Western Lowland gorilla. Postoperative photographs and radiographs indicated complete healing of the extraction sites. This case report includes a review of gorilla dental anatomy, oral disease in primates, pathogenesis of periodontal disease, predisposing factors to periodontal disease, and principles of surgical tooth extraction.

Fishes of Missouri River, chute, and flood plain habitats: Chapter 4 in Initial biotic survey of Lisbon Bottom, Big Muddy National Fish and Wildlife Refuge

USGS Publications Warehouse

Grady, Joanne; Milligan, Jim; Chapman, Duane C.; Ehrhardt, Ellen A.; Dieterman, Douglas J.; Galat, David L.; Hooker, John; Kubisiak, John; DeLonay, Aaron; Little, Edward E.; Robinson, Jack; Tibbs, John

1999-01-01

chub, ghost shiner, western silvery minnow, plains minnow, and blue sucker. Equally important to note are fish species that were not collected. The flathead chub, currently listed as State endangered and proposed for Federal listing, were not collected in any of the studies.Common fish species, collected in all seven sampling studies, included gizzard shad, common carp, river carpsucker, and freshwater drum. Paddlefish, skipjack herring, silver carp, white sucker, redfin shiner, western silvery minnow, bullhead minnow, and black bullhead were each collected in only one of the seven studies.Pflieger (1971) developed a guild system for the fishes of Missouri based on distribution patterns and centers of abundance. Fish were assigned to one of four primary faunal groups: Ozark, Big River, Lowland, and Prairie. Two secondary groups (Ozark-prairie and Ozark-lowland) were defined for species equally abundant and distributed in two of the primary areas. Two Ozark-prairie species, shorthead redhorse and white sucker, were collected on or near the Lisbon Bottom Unit.Big River species are found primarily in the Missouri and Mississippi Rivers. The environmental factors controlling fish distribution in these rivers appear to be substrate, current velocity, and turbidity. On or near the Lisbon Bottom Unit 18 Big River species were collected (Table 2).Lowland species are intolerant of siltation and high turbidity. They inhabit standing or slow-moving water with sand, fine gravel, and organic debris substrates. Two Lowland species, bullhead minnow and mosquitofish, were collected in connected scours on the Lisbon Bottom Unit.Prairie species have broader ecological tolerances than the Ozark and Lowland species. They are largely absent in high gradient streams and cool, clear waters. Prairie species make up a significant proportion of Missouri and Mississippi River fishes. Seven Prairie species were collected on or near the Lisbon Bottom Unit (Table 2).The last group, Wide

Alien roadside species more easily invade alpine than lowland plant communities in a subarctic mountain ecosystem.

PubMed

Lembrechts, Jonas J; Milbau, Ann; Nijs, Ivan

2014-01-01

Effects of roads on plant communities are not well known in cold-climate mountain ecosystems, where road building and development are expected to increase in future decades. Knowledge of the sensitivity of mountain plant communities to disturbance by roads is however important for future conservation purposes. We investigate the effects of roads on species richness and composition, including the plant strategies that are most affected, along three elevational gradients in a subarctic mountain ecosystem. We also examine whether mountain roads promote the introduction and invasion of alien plant species from the lowlands to the alpine zone. Observations of plant community composition were made together with abiotic, biotic and anthropogenic factors in 60 T-shaped transects. Alpine plant communities reacted differently to road disturbances than their lowland counterparts. On high elevations, the roadside species composition was more similar to that of the local natural communities. Less competitive and ruderal species were present at high compared with lower elevation roadsides. While the effects of roads thus seem to be mitigated in the alpine environment for plant species in general, mountain plant communities are more invasible than lowland communities. More precisely, relatively more alien species present in the roadside were found to invade into the surrounding natural community at high compared to low elevations. We conclude that effects of roads and introduction of alien species in lowlands cannot simply be extrapolated to the alpine and subarctic environment.

The hydroclimatology of UK droughts: evidence from newly recovered and reconstructed datasets from the late 19th century to present

NASA Astrophysics Data System (ADS)

Smith, K. A.; Hannaford, J.; Bloomfield, J.; McCarthy, M.; Parry, S.; Barker, L. J.; Svensson, C.; Tanguy, M.; Marchant, B.; McKenzie, A.; Legg, T.; Prudhomme, C.

2017-12-01

While the UK is regarded as a wet country, it has periodically suffered from major droughts which have caused serious environmental and societal impacts. Parts of the UK are water stressed and, in a warming world, changes to supply/demand balances could have major implications. There is a pressing need for improved tools for drought risk assessment, which is contingent on a proper understanding of past occurrence of droughts. However, our understanding of hydrological drought occurrence is grounded in the post-1960 period when most UK river flow and groundwater records commenced. As such, water resources planners would benefit from a more thorough assessment of historical drought characteristics and their variability. The multi-disciplinary `Historic Droughts' project thus aims to rigorously characterise droughts in the UK back to the 1890s to inform improved drought management. The foundation of this is a comprehensive characterisation of the hydroclimatology of UK droughts. Here, we present the results of this initiative, based on a hydrological reconstruction campaign of unparalleled scope and detail. Driven by rainfall and potential evapotranspiration data, extended in time using newly recovered observational records, hydro(geo)logical models are used to reconstruct, back to 1890, river flows for >300 catchments across the UK, and groundwater levels from >50 boreholes. The reconstructions are derived within a state-of-the-art modelling framework which allows a comprehensive assessment of uncertainty. A suite of indicators are then applied to these datasets to identify and characterise drought events, integrating precipitation, evapotranspiration, streamflow and groundwater. The work provides new insights into the spatial and temporal dynamics of hitherto poorly quantified late 19th and early 20th century droughts. Similarly, the assessment of temporal variability of drought characteristics benefits from the long timescale of the reconstructions, in turn

Measuring Density Stratification and Understanding its Impact on Sediment Transport in Fine-grained Rivers, Based on Observations from the Lower Yellow River, China

NASA Astrophysics Data System (ADS)

Moodie, A. J.; Nittrouer, J. A.; Ma, H.; Lamb, M. P.; Carlson, B.; Kineke, G. C.; Parker, G.

2017-12-01

being used to refine relations for sediment entrainment and sediment flux in sandy and muddy, lowland rivers and deltas.

Spatial interpolation of river channel topography using the shortest temporal distance

NASA Astrophysics Data System (ADS)

Zhang, Yanjun; Xian, Cuiling; Chen, Huajin; Grieneisen, Michael L.; Liu, Jiaming; Zhang, Minghua

2016-11-01

It is difficult to interpolate river channel topography due to complex anisotropy. As the anisotropy is often caused by river flow, especially the hydrodynamic and transport mechanisms, it is reasonable to incorporate flow velocity into topography interpolator for decreasing the effect of anisotropy. In this study, two new distance metrics defined as the time taken by water flow to travel between two locations are developed, and replace the spatial distance metric or Euclidean distance that is currently used to interpolate topography. One is a shortest temporal distance (STD) metric. The temporal distance (TD) of a path between two nodes is calculated by spatial distance divided by the tangent component of flow velocity along the path, and the STD is searched using the Dijkstra algorithm in all possible paths between two nodes. The other is a modified shortest temporal distance (MSTD) metric in which both the tangent and normal components of flow velocity were combined. They are used to construct the methods for the interpolation of river channel topography. The proposed methods are used to generate the topography of Wuhan Section of Changjiang River and compared with Universal Kriging (UK) and Inverse Distance Weighting (IDW). The results clearly showed that the STD and MSTD based on flow velocity were reliable spatial interpolators. The MSTD, followed by the STD, presents improvement in prediction accuracy relative to both UK and IDW.

Re-meandering of lowland streams: will disobeying the laws of geomorphology have ecological consequences?

PubMed

Pedersen, Morten Lauge; Kristensen, Klaus Kevin; Friberg, Nikolai

2014-01-01

We evaluated the restoration of physical habitats and its influence on macroinvertebrate community structure in 18 Danish lowland streams comprising six restored streams, six streams with little physical alteration and six channelized streams. We hypothesized that physical habitats and macroinvertebrate communities of restored streams would resemble those of natural streams, while those of the channelized streams would differ from both restored and near-natural streams. Physical habitats were surveyed for substrate composition, depth, width and current velocity. Macroinvertebrates were sampled along 100 m reaches in each stream, in edge habitats and in riffle/run habitats located in the center of the stream. Restoration significantly altered the physical conditions and affected the interactions between stream habitat heterogeneity and macroinvertebrate diversity. The substrate in the restored streams was dominated by pebble, whereas the substrate in the channelized and natural streams was dominated by sand. In the natural streams a relationship was identified between slope and pebble/gravel coverage, indicating a coupling of energy and substrate characteristics. Such a relationship did not occur in the channelized or in the restored streams where placement of large amounts of pebble/gravel distorted the natural relationship. The analyses revealed, a direct link between substrate heterogeneity and macroinvertebrate diversity in the natural streams. A similar relationship was not found in either the channelized or the restored streams, which we attribute to a de-coupling of the natural relationship between benthic community diversity and physical habitat diversity. Our study results suggest that restoration schemes should aim at restoring the natural physical structural complexity in the streams and at the same time enhance the possibility of re-generating the natural geomorphological processes sustaining the habitats in streams and rivers. Documentation of

Re-Meandering of Lowland Streams: Will Disobeying the Laws of Geomorphology Have Ecological Consequences?

PubMed Central

Pedersen, Morten Lauge; Kristensen, Klaus Kevin; Friberg, Nikolai

2014-01-01

We evaluated the restoration of physical habitats and its influence on macroinvertebrate community structure in 18 Danish lowland streams comprising six restored streams, six streams with little physical alteration and six channelized streams. We hypothesized that physical habitats and macroinvertebrate communities of restored streams would resemble those of natural streams, while those of the channelized streams would differ from both restored and near-natural streams. Physical habitats were surveyed for substrate composition, depth, width and current velocity. Macroinvertebrates were sampled along 100 m reaches in each stream, in edge habitats and in riffle/run habitats located in the center of the stream. Restoration significantly altered the physical conditions and affected the interactions between stream habitat heterogeneity and macroinvertebrate diversity. The substrate in the restored streams was dominated by pebble, whereas the substrate in the channelized and natural streams was dominated by sand. In the natural streams a relationship was identified between slope and pebble/gravel coverage, indicating a coupling of energy and substrate characteristics. Such a relationship did not occur in the channelized or in the restored streams where placement of large amounts of pebble/gravel distorted the natural relationship. The analyses revealed, a direct link between substrate heterogeneity and macroinvertebrate diversity in the natural streams. A similar relationship was not found in either the channelized or the restored streams, which we attribute to a de-coupling of the natural relationship between benthic community diversity and physical habitat diversity. Our study results suggest that restoration schemes should aim at restoring the natural physical structural complexity in the streams and at the same time enhance the possibility of re-generating the natural geomorphological processes sustaining the habitats in streams and rivers. Documentation of

Birds of the St. Croix River valley: Minnesota and Wisconsin

USGS Publications Warehouse

Faanes, Craig A.

1981-01-01

The St. Croix River Valley encompasses nearly 11,550 km2 in east-central Minnesota and northwestern Wisconsin. A wide range of habitats are available for birds including upland oak, lowland deciduous, maple-basswood, lowland and upland coniferous forests, natural basin wetlands, and grasslands. Situated in the north-central region of the United States, the valley is a biological 'crossroads' for many species. Because of the mixed affinities of plant communities, the valley includes the northern and southern range limits for a number of species. Also, because the valley lies near the forest-prairie transition zone, many typical western breeding species (e.g. pintail, western meadowlark, yellow-headed blackbird) breed in proximity to typical eastern species such as tufted titmouse, eastern meadowlark, and cardinal. From 1966 to 1980, I conducted extensive surveys of avian distribution and abundance in the St. Croix River Valley. I have supplemented the results of these surveys with published and unpublished observations contributed by many ornithologists. These additional data include compilations from Christmas Bird Counts sponsored by the National Audubon Society and from the Breeding Bird Survey coordinated by the U.S. Fish and Wildlife Service. Three hundred fourteen species have been recorded in the study area; data are presented on the migration period, nesting season distribution, winter distribution, relative abundance, and habitat use of each species. Recognizing the uniqueness of the area, and its importance not only to wildlife but also to man, the U.S. Congress designated the St. Croix a National Scenic Riverway. This action provided a considerable degree of protection to lands along and directly adjacent to the river. Unfortunately, no similar legal measure exists to protect lands away from the river. With the exception of the northern quarter of the St. Croix River Valley, agricultural interests have made significant inroads into the habitat base. The

Sediment supply as a driver of river evolution in the Amazon Basin

NASA Astrophysics Data System (ADS)

Ahmed, Joshua; Constantine, José Antonio; Dunne, Thomas; Legleiter, Carl; Lazarus, Eli D.

2015-04-01

The Amazon represents the only large river basin in the world where there is a sufficient range of sediment supplies and a lack of engineering controls to assess how sediment supply drives the evolution of meandering rivers. Despite recent analytical advances (Asahi et al., 2013; Pittaluga and Seminara, 2011), modern theory does not yet identify or explain the effects of externally imposed sediment supplies, a fundamental river characteristic, on meandering river evolution. These sediment supplies would be radically reduced by the construction of large dams proposed for the Amazon Basin (Finer and Jenkins, 2012). Here, we demonstrate that the sediment loads imposed by their respective drainage basins determine planform changes in lowland rivers across the Amazon. Our analysis, based on Landsat image sequences, indicates that rivers with high sediment loads draining the Andes and associated foreland basin experience annual migration rates that are on average four times faster than rivers with lower sediment loads draining the Central Amazon Trough and shields. Incidents of meander cutoff also occur more frequently along the rivers of the Andes and foreland basin, where the number of oxbows in the floodplains is more than twice that observed in the floodplains of the Central Amazon Trough and shields. Our results, which cannot be explained by differences in channel slope or hydrology, highlight the importance of sediment supply in modulating the ability of meandering alluvial rivers to reshape the floodplain environment through river migration. Asahi, K., Shimizu, Y., Nelson, J., Parker, G., 2013. Numerical simulation of river meandering with self-evolving banks. Journal of Geophysical Research: Earth Surface, 118(4), 2013JF002752. Finer, M., Jenkins, C.N., 2012. Proliferation of hydroelectric dams in the Andean Amazon and implications for Andes-Amazon connectivity. PLOS One, 7(4), e35126. Pittaluga, M.B., Seminara, G., 2011. Nonlinearity and unsteadiness in river

Evolutionary history of partible paternity in lowland South America

PubMed Central

Walker, Robert S.; Flinn, Mark V.; Hill, Kim R.

2010-01-01

Partible paternity, the conception belief that more than one man can contribute to the formation of a fetus, is common in lowland South America and characterized by nonexclusive mating relationships and various institutionalized forms of recognition and investment by multiple cofathers. Previous work has emphasized the fitness benefits for women where partible paternity beliefs facilitate paternal investment from multiple men and may reduce the risk of infanticide. In this comparative study of 128 lowland South American societies, the prevalence of partible paternity beliefs may be as much as two times as common as biologically correct beliefs in singular paternity. Partible paternity beliefs are nearly ubiquitous in four large language families—Carib, Pano, Tupi, and Macro-Je. Phylogenetic reconstruction suggests that partible paternity evolved deep in Amazonian prehistory at the root of a tentative Je-Carib-Tupi clade. Partible paternity often occurs with uxorilocal postmarital residence (males transfer), although there are exceptions. Partible paternity may have benefits for both sexes, especially in societies where essentially all offspring are said to have multiple fathers. Despite a decrease in paternity certainty, at least some men probably benefit (or mitigate costs) by increasing their number of extramarital partners, using sexual access to their wives to formalize male alliances, and/or sharing paternity with close kin. PMID:20974947

Bd on the beach: high prevalence of Batrachochytrium dendrobatidis in the lowland forests of Gorgona Island (Colombia, South America).

PubMed

Flechas, Sandra Victoria; Sarmiento, Carolina; Amézquita, Adolfo

2012-09-01

The amphibian chytrid fungus, Batrachochytrium dendrobatidis, Bd, has been implicated in the decimation and extinction of many amphibian populations worldwide, especially at mid and high elevations. Recent studies have demonstrated the presence of the pathogen in the lowlands from Australia and Central America. We extend here its elevational range by demonstrating its presence at the sea level, in the lowland forests of Gorgona Island, off the Pacific coast of Colombia. We conducted two field surveys, separated by four years, and diagnosed Bd by performing polymerase chain reactions on swab samples from the skin of five amphibian species. All species, including the Critically Endangered Atelopus elegans, tested positive for the pathogen, with prevalences between 3.9 % in A. elegans (in 2010) and 52 % in Pristimantis achatinus. Clinical signs of chytridiomycosis were not detected in any species. To our knowledge, this is the first report of B. dendrobatidis in tropical lowlands at sea level, where temperatures may exceed optimal growth temperatures of this pathogen. This finding highlights the need to understand the mechanisms allowing the interaction between frogs and pathogen in lowland ecosystems.

New Evidence For A Late Miocene Onset Of The Amazon River Following Andean Tectonics And Quaternary Climate Change

NASA Astrophysics Data System (ADS)

Hoorn, M. C.; Bogota-Angel, G.; Romero-Baez, M.; Lammertsma, E.; Flantua, S. G. A.; Dantas, E. L.; Dino, R.; do Carmo, D.; Chemale, F., Jr.

2017-12-01

The Amazon River influenced biotic evolution on land and at sea, but its onset and development are still debated. Terrestrial sedimentary records are sparse, far apart, and do not present a continuous stratigraphy and thus greatly complicate the reconstruction of the history of this river system. At sea the stratigraphic record is better known thanks to hydrocarbon exploration efforts, but these data are not in the public domain. Renewed exploration in the Amazon submarine fan (Brazilian Equatorial Margin) has provided novel data and materials from wells drilled along the slope of the Amazon submarine fan, that are now partially available for scientific research. Here we report on the results of a geochemical and palynological study of `Well 2' based on which we determined the age and provenance of early Miocene to Pleistocene sediments. The palynological data were also used to reconstruct past biomes on land, which ranged from mangrove and lowland forest to alpine vegetation. A distinct change in provenance was observed between 9.4 Ma and 9 Ma, which represented a change from Amazonian to Andean sediment source. This signal is replicated in the palynological record, which shows a shift from lowland to high-mountain taxa. Furthermore, we observed a very large increase of grass pollen from the Pliocene onwards with a further rise in the Pleistocene. These changes coincide with a rise in sedimentation rates. We interpret these results as following: a) the arrival of Andean sediments is related to the onset of the transcontinental river, b) the two-step rise of grass pollen and manifold increase in sediment discharge are related to Quaternary climatic change. These results agree with earlier and recent findings on the Ceara Rise and firmly place the birth of this river in the late Miocene. This study exemplifies the continental scale of tectonic changes on fluvial environments and biota across a W-E transect of South America. The study of this well is continued and we

Deglaciation of the James Bay Lowlands and Northern Abitibi: Insights on Late-Glacial Ice Readvances and Drainage of Glacial Lake Ojibway

NASA Astrophysics Data System (ADS)

Roy, M.; Veillette, J. J.; Dell'Oste, F.

2008-12-01

Deglaciation in the James Bay region was marked by the scission of the Laurentide ice sheet margin into the Hudson dome to the west and the New-Quebec dome to the east, which subsequently retreated northward, in contact with the waters of glacial Lake Ojibway. Previous work based on air photo-interpretation and field observations indicate that ice retreat in the region was highly dynamic, with the occurrence of at least three ice readvances into the basin of Lake Objiway prior to the final deglaciation, and the incursion of the post- glacial Tyrrell Sea at ~8 ka (Hardy, 1976). Our investigations of stratigraphic sections exposed along the Harricana, Nottaway, Broadback, and Rupert rivers in the lowlands of Quebec indicate that only part of these events are preserved in these sedimentary sequences. The base of the late-glacial sequence generally consists of a carbonate-bearing clayey readvance till that lies on older tills of the last glacial cycle, or truncate Lake Ojibway glaciolacustrine sediments. None of the sections showed more than one till of the three (Cochrane I, Rupert, Cochrane II) readvances documented in the region. Nonetheless, an extensive Ojibway sequence located just south from the lowlands shows three intervals with significant increases in detrital carbonate and coarsening of the varve sequence that can be linked with these late-glacial surges. In the lowlands, the readvance till is commonly capped by a thick sequence of Ojibway varves. The contact between the glaciolacustrine sediments and the overlying Tyrrell Sea marine deposits is marked by a ~50 cm-thick horizon composed at the bottom of thinly laminated reddish and grey silt beds containing abundant rounded clay balls, overlain by coarser silts and fine sands with disseminated clasts. This horizon is here interpreted to reflect the abrupt drainage of Lake Ojibway. Recent radiocarbon dating of mollusks and foraminifers from the uppermost part of this horizon yielded ages of ~7.7 ka and ~8

Improving estuary models by reducing uncertainties associated with river flows

NASA Astrophysics Data System (ADS)

Robins, Peter E.; Lewis, Matt J.; Freer, Jim; Cooper, David M.; Skinner, Christopher J.; Coulthard, Tom J.

2018-07-01

To mitigate against future changes to estuaries such as water quality, catchment and estuary models can be coupled to simulate the transport of harmful pathogenic viruses, pollutants and nutrients from their terrestrial sources, through the estuary and to the coast. To predict future changes to estuaries, daily mean river flow projections are typically used. We show that this approach cannot resolve higher frequency discharge events that have large impacts to estuarine dilution, contamination and recovery for two contrasting estuaries. We therefore characterise sub-daily scale flow variability and propagate this through an estuary model to provide robust estimates of impacts for the future. River flow data (35-year records at 15-min sampling) were used to characterise variabilities in storm hydrograph shapes and simulate the estuarine response. In particular, we modelled a fast-responding catchment-estuary system (Conwy, UK), where the natural variability in hydrograph shapes generated large variability in estuarine circulation that was not captured when using daily-averaged river forcing. In the extreme, the freshwater plume from a 'flash' flood (lasting <12 h) was underestimated by up to 100% - and the response to nutrient loading was underestimated further still. A model of a slower-responding system (Humber, UK), where hydrographs typically last 2-4 days, showed less variability in estuarine circulation and good approximation with daily-averaged flow forcing. Our result has implications for entire system impact modelling; when we determine future changes to estuaries, some systems will need higher resolution future river flow estimates.

Classic Period collapse of the Central Maya Lowlands: Insights about human–environment relationships for sustainability

PubMed Central

Turner, B. L.; Sabloff, Jeremy A.

2012-01-01

The ninth century collapse and abandonment of the Central Maya Lowlands in the Yucatán peninsular region were the result of complex human–environment interactions. Large-scale Maya landscape alterations and demands placed on resources and ecosystem services generated high-stress environmental conditions that were amplified by increasing climatic aridity. Coincident with this stress, the flow of commerce shifted from land transit across the peninsula to sea-borne transit around it. These changing socioeconomic and environmental conditions generated increasing societal conflicts, diminished control by the Maya elite, and led to decisions to move elsewhere in the peninsular region rather than incur the high costs of maintaining the human–environment systems in place. After abandonment, the environment of the Central Maya Lowlands largely recovered, although altered from its state before Maya occupation; the population never recovered. This history and the spatial and temporal variability in the pattern of collapse and abandonment throughout the Maya lowlands support the case for different conditions, opportunities, and constraints in the prevailing human–environment systems and the decisions to confront them. The Maya case lends insights for the use of paleo- and historical analogs to inform contemporary global environmental change and sustainability. PMID:22912403

Classic Period collapse of the Central Maya Lowlands: insights about human-environment relationships for sustainability.

PubMed

Turner, B L; Sabloff, Jeremy A

2012-08-28

The ninth century collapse and abandonment of the Central Maya Lowlands in the Yucatán peninsular region were the result of complex human-environment interactions. Large-scale Maya landscape alterations and demands placed on resources and ecosystem services generated high-stress environmental conditions that were amplified by increasing climatic aridity. Coincident with this stress, the flow of commerce shifted from land transit across the peninsula to sea-borne transit around it. These changing socioeconomic and environmental conditions generated increasing societal conflicts, diminished control by the Maya elite, and led to decisions to move elsewhere in the peninsular region rather than incur the high costs of maintaining the human-environment systems in place. After abandonment, the environment of the Central Maya Lowlands largely recovered, although altered from its state before Maya occupation; the population never recovered. This history and the spatial and temporal variability in the pattern of collapse and abandonment throughout the Maya lowlands support the case for different conditions, opportunities, and constraints in the prevailing human-environment systems and the decisions to confront them. The Maya case lends insights for the use of paleo- and historical analogs to inform contemporary global environmental change and sustainability.

Effects of climate change on water abstraction restrictions for irrigation during droughts - The UK case

NASA Astrophysics Data System (ADS)

Rey Vicario, D.; Holman, I.

2016-12-01

The use of water for irrigation and on-farm reservoir filling is globally important for agricultural production. In humid climates, like the UK, supplemental irrigation can be critical to buffer the effects of rainfall variability and to achieve high quality crops. Given regulatory efforts to secure sufficient environmental river flows and meet rising water demands due to population growth and climate change, increasing water scarcity is likely to compound the drought challenges faced by irrigated agriculture in this region. Currently, water abstraction from surface waters for agricultural irrigation can be restricted by the Environment Agency during droughts under Section 57 of the Water Resources Act (1991), based on abnormally low river flow levels and rainfall forecast, causing significant economic impacts on irrigated agricultural production. The aim of this study is to assess the impact that climate change may have on agricultural abstraction in the UK within the context of the abstraction restriction triggers currently in place. These triggers have been applied to the `Future Flows hydrology' database to assess the likelihood of increasing restrictions on agricultural abstraction in the future by comparing the probability of voluntary and compulsory restrictions in the baseline (1961-1990) and future period (2071-2098) for 282 catchments throughout the whole of the UK. The results of this study show a general increase in the probability of future agricultural irrigation abstraction restrictions in the UK in the summer, particularly in the South West, although there is significant variability between the 11 ensemble members. The results also indicate that UK winters are likely to become wetter in the future, although in some catchments the probability of abstraction restriction in the reservoir refilling winter months (November-February) could increase slightly. An increasing frequency of drought events due to climate change is therefore likely to lead to

Patterns of Sexual Behavior in Lowland Thai Youth and Ethnic Minorities Attending High School in Rural Chiang Mai, Thailand.

PubMed

Aurpibul, Linda; Tangmunkongvorakul, Arunrat; Musumari, Patou Masika; Srithanaviboonchai, Kriengkrai; Tarnkehard, Surapee

2016-01-01

The rural areas of Northern Thailand are home to a large cultural diversity of ethnic minority groups. Previous studies have shown that young people in rural Thailand have low levels of knowledge on HIV/AIDS and high sexual risks. We compared sexual behaviors between the lowland Thai youth and the youth from ethnic minority groups. This is a cross-sectional quantitative study conducted among high-school Thai and ethnic students in Chiang Mai. From a total 1215 participants, 487 (40.1%) were lowland Thai and 728 (59.9%) were from ethnic minorities. Overall, 17.9% of respondents reported "ever had sex." Lowland Thai adolescents were more likely to have ever had sex compared with ethnic minority adolescents (AOR, 1.61; CI, 1.06-2.45; P< 0.01). A higher proportion of lowland Thai respondents reported having ≥ 2 lifetime sexual partners (51.9% vs. 33.3%, P = 0.003), or currently having a boy/girlfriend (59.9% vs. 45.3%, P< 0.001) compared to ethnic minority adolescents. Consistent condom use was low in both groups (22.6%). The common significant factors associated with "ever had sex" in both groups were "ever drunk alcohol in the past year" and "currently having a boy/girlfriend." Specifically, for lowland Thai youth, being around the age of 17 or 18 years and "ever used methamphetamine in the past year" were associated with increased odds of "ever had sex". For ethnic minority adolescents, being female and belonging to religions other than Buddhism were associated with decreased odds of "ever had sex". A substantially higher proportion of lowland Thai engage in risky sexual behaviors when compared to ethnic minorities. However, both groups remained vulnerable to HIV and other sexually transmitted infections. To minimize sexual risks, education program and school-based interventions are warranted to increase awareness of young people about risky behaviors and to promote essential life skills.

Patterns of Sexual Behavior in Lowland Thai Youth and Ethnic Minorities Attending High School in Rural Chiang Mai, Thailand

PubMed Central

Aurpibul, Linda; Tangmunkongvorakul, Arunrat; Musumari, Patou Masika; Srithanaviboonchai, Kriengkrai; Tarnkehard, Surapee

2016-01-01

Introduction The rural areas of Northern Thailand are home to a large cultural diversity of ethnic minority groups. Previous studies have shown that young people in rural Thailand have low levels of knowledge on HIV/AIDS and high sexual risks. We compared sexual behaviors between the lowland Thai youth and the youth from ethnic minority groups. Methods and findings This is a cross-sectional quantitative study conducted among high-school Thai and ethnic students in Chiang Mai. From a total 1215 participants, 487 (40.1%) were lowland Thai and 728 (59.9%) were from ethnic minorities. Overall, 17.9% of respondents reported “ever had sex.” Lowland Thai adolescents were more likely to have ever had sex compared with ethnic minority adolescents (AOR, 1.61; CI, 1.06–2.45; P< 0.01). A higher proportion of lowland Thai respondents reported having ≥ 2 lifetime sexual partners (51.9% vs. 33.3%, P = 0.003), or currently having a boy/girlfriend (59.9% vs. 45.3%, P< 0.001) compared to ethnic minority adolescents. Consistent condom use was low in both groups (22.6%). The common significant factors associated with "ever had sex" in both groups were "ever drunk alcohol in the past year" and "currently having a boy/girlfriend." Specifically, for lowland Thai youth, being around the age of 17 or 18 years and "ever used methamphetamine in the past year" were associated with increased odds of “ever had sex”. For ethnic minority adolescents, being female and belonging to religions other than Buddhism were associated with decreased odds of “ever had sex”. Conclusion A substantially higher proportion of lowland Thai engage in risky sexual behaviors when compared to ethnic minorities. However, both groups remained vulnerable to HIV and other sexually transmitted infections. To minimize sexual risks, education program and school-based interventions are warranted to increase awareness of young people about risky behaviors and to promote essential life skills. PMID:27906980

Land, Water and Society in the Maya Lowlands

NASA Astrophysics Data System (ADS)

Murtha, T.; French, K.; Duffy, C.; Webster, D.

2013-12-01

This paper reports the results of our project investigating the long-term spatial and temporal dynamics of land use management, agricultural decision-making and patterns of resource availability in the tropical lowlands of Central America. Overall, our project combines diachronic environmental simulation with historic settlement pattern survey to address a series of long-standing questions about the coupled natural and human (CNH) landscape history in the Central Maya lowlands (at the UNESCO world heritage site of Tikal in the Maya Biosphere Reserve). The paper describes the preliminary results of our project, including changing patterns of land, water, settlement and political history using climate, soil and hydrologic modeling and time series spatial analysis of population and settlement patterns. The critical period of the study, 1000 BC until the present, begins with dispersed settlements accompanied by widespread deforestation and soil erosion. Population size and density grows rapidly for 800 years, while deforestation and erosion rates decline; however, there is striking evidence of political evolution during this period, including the construction of monumental architecture, hieroglyphic monuments detailing wars and alliances, and the construction of a defensive earthwork feature, signaling political territories and possibly delineating natural resource boundaries. Population decline and steady reforestation followed until more recent migration into the region, which has impacted the biosphere ecology. Building on our previous research regionally and comparative research completed in Belize and Mexico, we are modeling sample periods the 3,000-year landscape history of the region, comparing land and water availability to population distributions and what we know about political history. Simulations are generated using historic climate and land use data, primarily relying on the Erosion Productivity Impact Calculator (EPIC) and the Penn State Integrated

Geohydrology of the lowland lakes area, Anchorage, Alaska

USGS Publications Warehouse

Zenone, Chester

1976-01-01

Unconsolidated deposits, chiefly of glacial origin, make up the surficial geologic materials in the Anchorage lowland lakes area , the western part of the Anchorage glacial outwash plain. Postglacial accumulation of peat, commonly 5 to 10 feet thick, and the presence of ground water at or very near the surface combine to create the swamp-muskeg terrane of much of the area. Deeper, confined ground water is also present beneath thick silt and clay layers that underlie the surficial deposits. Domestic water supply for the lowland lakes area is provided largely by public-supply wells completed in the deep, confined aquifers. No large perennial streams traverse the area, thus streamflow is not a major parameter in the area 's natural water balance. The major uses of surface water are recreational, including fishing and boating at several of the larger lakes, and private and commercial aircraft operations at Hood-Spenard Lakes floatplane base. The hydrology and water balance of these lakes is complex. Water levels in some lakes appear to be closely related to adjacent ground-water levels. Other lakes are evidently perched above the local water table. The relation of lake level to adjacent ground-water level may vary along the shoreline of a single lake. The effect of residential development practices on lake basin water balance is not completely understood. At Sand Lake, the largest lake in this area of rapid urbanization, the water level has declined about 6 feet since the early 1960's. (Woodard-USGS)

Biochemical evidence for minimal vegetation change in peatlands of the West Siberian Lowland during the Medieval Climate Anomaly and Little Ice Age

NASA Astrophysics Data System (ADS)

Philben, Michael; Kaiser, Karl; Benner, Ronald

2014-05-01

Peatland vegetation is controlled primarily by the depth of the water table, making peat paleovegetation a useful climate archive. We applied a biochemical approach to quantitatively estimate the plant sources of peat carbon based on (1) neutral sugar compositions of Sphagnum, vascular plants, and lichens and (2) lignin phenol compositions of vascular plants. We used these biochemical indices to characterize vegetation change over the last 2000 years in four peat cores from the West Siberian Lowland (Russia) to investigate climate change during the Medieval Climate Anomaly and Little Ice Age. The vegetation was dominated by Sphagnum in all four cores, but was punctuated by several rapid but transient transitions to vascular plant dominance in the two cores from the southern West Siberian Lowland (<60°N latitude). Lichen contributions were evident at the end of the Medieval Climate Anomaly and during the Little Ice Age in the two cores from northern West Siberian Lowland (>60°N), possibly indicating permafrost development. However, there was no evidence for sustained vegetation change in response to either climatic event in cores from southern West Siberian Lowland. This suggests that these climatic events were relatively mild in the southern West Siberian Lowland, although the sensitivity of bog plant communities to climate change remains poorly understood.

Relative Ages of the Highlands, Lowlands, and Transition Zone Along a Portion of the Mars Crustal Dichotomy from Densities of Visible and Buried Impact Craters

NASA Technical Reports Server (NTRS)

DeSoto, G. E.; Frey, H. V.

2005-01-01

Understanding the fundamental age relationships of the different parts of the Mars Crustal Dichotomy is essential to fully understanding the events that shaped the early history and formation of the surface of Mars. A dominant question is what are the true relative ages of the Northern Lowlands and the Southern Highlands? Using MOLA data from the Mars Global Surveyor and Viking visual images, a dataset of both buried and visible crater diameters was created over a nine million sq km study area of a section of the dichotomy boundary stretching from Arabia Terra to Utopia Planitia. Cumulative frequency plots on a log-log scale were used to determine the relative ages for the Highlands, the Lowlands, and the Transition Zone, separately for the visible, the buried and the combined total (visible+ buried) populations. We find the overall Highland crater population in this area is slightly older than the Lowlands, consistent with previous global studies, but the Lowlands and Transition Zone are also very old and formed at roughly the same time. It appears that the formation of the Lowlands in this region formed contemporaneously with a large-scale resurfacing event in the Highlands, perhaps caused by the process responsible for the Lowland formation.

River response to land use change and sediment control works: the case of the Reno river in Italy

NASA Astrophysics Data System (ADS)

Billi, P.; Salemi, E.; Preciso, E.

2012-04-01

The Reno River is the eleventh largest river in Italy. It has been extensively affected by man activity for a very long span of time. The first relevant impacts date back to the Romans time and were reiterated with more or less intensity until present. During the last five centuries, the lowland portion of the river was subjected to remarkable channel modifications, diversion, levee construction, reclamation of the this portion of the Po plain. In the recent decades, mainly after World War II, , significant land use changes in the headwater, extensive bed material mining, dams construction, torrent-control works and large fluids extraction from the underground caused important channel morphology and sediment fluxes changes. Three main effects of such human impacts are evident: a remarkable streambed degradation (as much as 5 m during the last 60 years), the reduction to a hard to detect quantity of bedload flux and, consequently, a worrying beach erosion. Two main types of channel adjustment, riverbed incision and channel narrowing, were observed. Riverbed degradation is discussed by comparing 4 different longitudinal profiles surveyed in 1928, 1951, 1970 and 1998 in the 120 km long reach upstream of the outlet. The analysis of channel narrowing is carried out by comparing a number of cross-sections surveyed in different years across the same downstream reach. Moreover, in order to understand such morphological changes, their causes and, possibly, to envisage some solutions land use changes analysis and a field campaign of sediment transport measurement were carried out in the 2003 - 2006. Though the fine material release from soil erosion processes on slopes resulted in suspended sediment transport concentration and rate not very different from those of rivers with similar physiography, landscape and catchment size, bedload transport rate resulted very low also during floods larger than bankfull. The effect of climate change was anlysed as well.

Divergent biophysical controls of aquatic CO2 and CH4 in the World’s two largest rivers

PubMed Central

Borges, Alberto V.; Abril, Gwenaël; Darchambeau, François; Teodoru, Cristian R.; Deborde, Jonathan; Vidal, Luciana O.; Lambert, Thibault; Bouillon, Steven

2015-01-01

Carbon emissions to the atmosphere from inland waters are globally significant and mainly occur at tropical latitudes. However, processes controlling the intensity of CO2 and CH4 emissions from tropical inland waters remain poorly understood. Here, we report a data-set of concurrent measurements of the partial pressure of CO2 (pCO2) and dissolved CH4 concentrations in the Amazon (n = 136) and the Congo (n = 280) Rivers. The pCO2 values in the Amazon mainstem were significantly higher than in the Congo, contrasting with CH4 concentrations that were higher in the Congo than in the Amazon. Large-scale patterns in pCO2 across different lowland tropical basins can be apprehended with a relatively simple statistical model related to the extent of wetlands within the basin, showing that, in addition to non-flooded vegetation, wetlands also contribute to CO2 in river channels. On the other hand, dynamics of dissolved CH4 in river channels are less straightforward to predict, and are related to the way hydrology modulates the connectivity between wetlands and river channels. PMID:26494107

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.

Enhancing mud supply from the Lower Missouri River to the Mississippi River Delta USA: Dam bypassing and coastal restoration

NASA Astrophysics Data System (ADS)

Kemp, G. Paul; Day, John W.; Rogers, J. David; Giosan, Liviu; Peyronnin, Natalie

2016-12-01

Sand transport to the Mississippi River Delta (MRD) remains sufficient to build wetlands in shallow, sheltered coastal bays fed by engineered diversions on the Mississippi River (MR) and its Atchafalaya River (AR) distributary. But suspended mud (silt & clay) flux to the coast has dropped from a mean of 390 Mt y-1 in the early 1950s, to 100 Mt y-1 since 1970. This fine-grained sediment travels deeper into receiving estuarine basins and plays a critical role in sustaining existing marshes. Virtually all of the 300 Mt y-1 of missing mud once flowed from the Missouri River (MOR) Basin before nearly 100 dams were built as part of the Pick-Sloan water development project. About 100 Mt y-1 is now intercepted by main-stem Upper MOR dams closed in 1953. But the remaining 200 Mt y-1 is trapped by impoundments built on tributaries to the Lower MOR in the 1950s and 1960s. Sediment flux during the post-dam high MOR discharge years of 1973, 1993 and 2011 approached pre-dam levels when tributaries to the Lower MOR, including the Platte and Kansas Rivers, contributed to flood flows. West bank tributaries drain a vast, arid part of the Great Plains, while those entering from the east bank traverse the lowlands of the MOR floodplain. Both provinces are dominated by highly erodible loess soils. Staunching the continued decline in MR fine-grained sediment flux has assumed greater importance now that engineered diversions are being built to reconnect the Lowermost MR to the MRD. Tributary dam bypassing in the Lower MOR basin could increase mud supply to the MRD by 100-200 Mt y-1 within 1-2 decades. Such emergency measures to save the MRD are compatible with objectives of the Missouri River Restoration and Platte River Recovery Programs to restore MOR riparian habitat for endangered species. Rapid mobilization to shunt fine-grained sediments past as many as 50 Lower MOR tributary dams in several U.S. states will undoubtedly require as much regional coordination and funding in the 21st

Mineralogical Composition of Particle-Size Fractions of Solonetzes from the North Crimean Lowland

NASA Astrophysics Data System (ADS)

Chizhikova, N. P.; Khitrov, N. B.; Tronza, G. E.; Kol'tsov, S. A.; Varlamov, E. B.; Chechetko, E. S.; Churilin, N. A.

2017-12-01

Data on the mineralogical composition of clay (<1 μm), fine silt (1-5 μm), medium silt (5-10 μm), and coarser (>10 μm) fractions of meadow solonchakous solonetzes (Calcic Gypsic Salic Stagnic Solonetz (Albic, Siltic, Columnic, Cutanic, Differentic)) developing from loesslike loam and clay in the North Crimean Lowland are presented. Fractions >5 μm constitute nearly 50% of the soil mass and are characterized by the same mineralogical composition in the entire profile; they consist of quartz, plagioclases, potassium feldspars, and micas (biotite and muscovite). The eluvial-illuvial redistribution of clay in the course of solonetzic process is accompanied by changes in the portion of mixed-layer minerals and hydromicas in the upper part of the profile; a larger part of the smectitic phase is transformed into the superdisperse state. In the eluvial SEL horizon and in the illuvial BSN horizon, the clay fraction is impoverished in smectitic phase and enriched in trioctahedral hydromicas. Upon calculation of the content of clay minerals per bulk soil mass, the distribution of mixed-layer minerals is either eluvial, or eluvial-illuvial, whereas the distribution of hydromicas has an illuvial pattern without distinct eluvial minimum in the SEL horizons. The eluvial-illuvial distribution pattern of clay minerals in solonetzes of the North Crimean Lowland is compared with the distribution pattern of clay minerals in solonetzes of the West Siberian Lowland. Coefficients characterizing differentiation of solonetzes by the contents of particular mineral components are suggested.

Process Based Modelling of Climate Change Impacts on River Water Quality: Case studies from the England, Wales and Scotland

NASA Astrophysics Data System (ADS)

Whitehead, P. G.; Jin, L.; Futter, M.; Crossman, J.

2011-12-01

A modelling study has been undertaken as part of a UK Water Industry Research Project to study and assess the likely impacts of climate change on river water quality across the UK. A range of climate scenarios (http://ukclimateprojections.defra.gov.uk/ ) have been used to generate future precipitation, evaporation and temperature time series at a range of catchments across the UK. These time series have then been used to drive the Integrated Catchment Model (INCA) suite to simulate flow, nitrate, ammonia, total and soluble reactive phosphorus, sediments, dissolved organic carbon (DOC) in the Rivers Tamar, Lugg, Tame, Kennet, Tweed and Lambourn. A wide range of responses have been obtained with impacts varying depending on river character, catchment location, flow regime, type of scenario and the time into the future. For example, The INCA-DOC model has been applied to the Hore catchment of the upper Severn catchment at Plynlimon, Wales. DOC is becoming an issue in the UK uplands due to rising trends in recent years. The trends are thought to be due primarily to reducing sulphur deposition but the climate variability certainly has an effect. This is because when peats dry out the oxidation processes enhance the production of DOC. The INCA-DOC model has been used to assess potential changes in DOC under the 2020s and 2050s climate. These results show quite large rises in October and September months when the soils become saturated and flush DOC. The INCA-N results for the Rivers Tweed (Scotland) and Kennet (England) suggest that nitrate and ammonia concentrations will be slightly higher in the winter months under the climate change scenarios, perhaps reflecting the higher flushing of nitrogen load from the catchment soils. However, in summer month nitrates fall significantly which reflects enhanced denitrification processes in the rivers. However, lower down the rivers where major point sources from effluents affect the river, nitrates and ammonia may increase

Characterisation of a major phytoplankton bloom in the River Thames (UK) using flow cytometry and high performance liquid chromatography.

PubMed

Moorhouse, H L; Read, D S; McGowan, S; Wagner, M; Roberts, C; Armstrong, L K; Nicholls, D J E; Wickham, H D; Hutchins, M G; Bowes, M J

2018-05-15

Recent river studies have observed rapid phytoplankton dynamics, driven by diurnal cycling and short-term responses to storm events, highlighting the need to adopt new high-frequency characterisation methods to understand these complex ecological systems. This study utilised two such analytical methods; pigment analysis by high performance liquid chromatography (HPLC) and cell counting by flow cytometry (FCM), alongside traditional chlorophyll spectrophotometry and light microscopy screening, to characterise the major phytoplankton bloom of 2015 in the River Thames, UK. All analytical techniques observed a rapid increase in chlorophyll a concentration and cell abundances from March to early June, caused primarily by a diatom bloom. Light microscopy identified a shift from pennate to centric diatoms during this period. The initial diatom bloom coincided with increased HPLC peridinin concentrations, indicating the presence of dinoflagellates which were likely to be consuming the diatom population. The diatom bloom declined rapidly in early June, coinciding with a storm event. There were low chlorophyll a concentrations (by both HPLC and spectrophotometric methods) throughout July and August, implying low biomass and phytoplankton activity. However, FCM revealed high abundances of pico-chlorophytes and cyanobacteria through July and August, showing that phytoplankton communities remain active and abundant throughout the summer period. In combination, these techniques are able to simultaneously characterise a wider range of phytoplankton groups, with greater certainty, and provide improved understanding of phytoplankton functioning (e.g. production of UV inhibiting pigments by cyanobacteria in response to high light levels) and ecological status (through examination of pigment degradation products). Combined HPLC and FCM analyses offer rapid and cost-effective characterisation of phytoplankton communities at appropriate timescales. This will allow a more-targeted use

Seeing the landscape for the trees: Metrics to guide riparian shade management in river catchments

NASA Astrophysics Data System (ADS)

Johnson, Matthew F.; Wilby, Robert L.

2015-05-01

Rising water temperature (Tw) due to anthropogenic climate change may have serious consequences for river ecosystems. Conservation and/or expansion of riparian shade could counter warming and buy time for ecosystems to adapt. However, sensitivity of river reaches to direct solar radiation is highly heterogeneous in space and time, so benefits of shading are also expected to be site specific. We use a network of high-resolution temperature measurements from two upland rivers in the UK, in conjunction with topographic shade modeling, to assess the relative significance of landscape and riparian shade to the thermal behavior of river reaches. Trees occupy 7% of the study catchments (comparable with the UK national average) yet shade covers 52% of the area and is concentrated along river corridors. Riparian shade is most beneficial for managing Tw at distances 5-20 km downstream from the source of the rivers where discharge is modest, flow is dominated by near-surface hydrological pathways, there is a wide floodplain with little landscape shade, and where cumulative solar exposure times are sufficient to affect Tw. For the rivers studied, we find that approximately 0.5 km of complete shade is necessary to off-set Tw by 1°C during July (the month with peak Tw) at a headwater site; whereas 1.1 km of shade is required 25 km downstream. Further research is needed to assess the integrated effect of future changes in air temperature, sunshine duration, direct solar radiation, and downward diffuse radiation on Tw to help tree planting schemes achieve intended outcomes.

Provenance of tetraether membrane lipids in a large temperate lake (Loch Lomond, UK): implications for glycerol dialkyl glycerol tetraether (GDGT)-based palaeothermometry

NASA Astrophysics Data System (ADS)

Buckles, L. K.; Weijers, J. W. H.; Tran, X.-M.; Waldron, S.; Sinninghe Damsté, J. S.

2014-10-01

The application of glycerol dialkyl glycerol tetraether (GDGT)-based palaeoenvironmental proxies, such as the branched vs. isoprenoidal tetratether (BIT) index, TEX86 and the MBT-CBT palaeothermometer, has lately been expanded to lacustrine sediments. Given recent research identifying the production of branched, bacterial GDGTs (brGDGTs) within lakes, it is necessary to ascertain the effect of this lacustrine production on GDGT-based proxies. This study profiles a temperate, monomictic lake (Loch Lomond, UK), analysing labile intact polar GDGT lipids (IPLs) and resilient core GDGT lipids (CLs) in catchment soils, small tributary rivers, lake water and lake sediments. Loch Lomond consists of two basins bisected by the Highland Boundary Fault, resulting in a mesotrophic to oligotrophic gradient from south to north. The north basin is fjord-like, while the south basin is shallow with a lowland catchment. Besides abundant influxes of allochthonous soil- and peat-derived (CL) brGDGTs, brGDGTs are produced in a variety of settings in Loch Lomond. Rather than integrating a scattered soil signal, there is some evidence that small rivers may contribute to the brGDGT pool through addition of brGDGTs produced in situ in these streams. Three hundred days of settling particles and water column profiles of suspended particulate matter (SPM; March and September 2011) reveal brGDGT production throughout the water column, with (IPL and CL) brGDGT distributions varying by basin. In lake sediments, in situ brGDGT production affects the distributions of sedimentary brGDGTs despite high soil- and peat-derived organic matter influxes from the catchment. MBT-CBT-derived mean annual air temperature (MAAT) estimates from soil, river and lake sediments vary widely. A strong bias towards higher MAATs in the south and lower MAATs in the north basin further complicates the application of the proxy. These results emphasise that caution must be exercised when applying the MBT

Sleep Architecture in Partially Acclimatized Lowlanders and Native Tibetans at 3800 Meter Altitude: What Are the Differences?

PubMed

Kong, Fanyi; Liu, Shixiang; Li, Qiong; Wang, Lin

2015-09-01

It is not well known whether high altitude acclimatization could help lowlanders improve their sleep architecture as well as Native Tibetans. In order to address this, we investigated the structural differences in sleep between Native Tibetans and partially acclimatized lowlanders and examined the association between sleep architecture and subjective sleep quality. Partially acclimatized soldiers from lowlands and Native Tibetan soldiers stationed at Shangri-La (3800 m) were surveyed using the Pittsburgh Sleep Quality Index (PSQI), Hamilton Anxiety Scale (HAMA), and Hamilton Depression Rating Scale (HAMD). The sleep architecture of those without anxiety (as determined by HAMA>14) and/or depression (HAMD>20) was analyzed using polysomnography and the results were compared between the two groups. One hundred sixty-five male soldiers, including 55 Native Tibetans, were included in the study. After partial acclimatization, lowlanders still exhibited differences in sleep architecture as compared to Native Tibetans, as indicated by a higher PSQI score (8.14±2.37 vs. 3.90±2.85, p<0.001), shorter non-rapid eye movement (non-REM) sleep (458.68±112.63 vs. 501±37.82 min, P=0.03), lower nocturnal arterial oxygen saturation (Spo2; mean 91.39±1.24 vs. 92.71±2.12%, p=0.03), and increased times of Spo2 reduction from 89% to 85% (median 48 vs.17, p=0.04) than Native Tibetans. Sleep onset latency (β=0.08, 95%CI: 0.01 to 0.15), non-REM latency (β=0.011, 95%CI 0.001 to 0.02), mean Spo2 (β=-0.79, 95%CI: -1.35 to -0.23) and time in stage 3+4 sleep (β=-0.014, 95%CI: -0.001 to -0.028) were slightly associated with the PSQI score. Partially acclimatized lowlanders experienced less time in non-REM sleep and had lower arterial oxygen saturation than Native Tibetans at an altitude of 3800 m. The main independent contributors to poor sleep quality are hypoxemia, difficulty in sleep induction, and time in deep sleep.

Aplication of giberelins on flowering and yield of two varieties of shallot in lowland

NASA Astrophysics Data System (ADS)

Triharyanto, E.; Nyoto, S.; Yusrifani, I.

2018-03-01

Shallot is one of horticultural commodities which has difficulties in flowering and producing seeds. Flowering of shallot generally occurs in highlands at 9-12° C. Flowering in lowland can be supported with vernalization or replace cold temperature with gibberelin (GA3). This research is aimed to determine the effect of varieties, the concentration of GA3 applied and their interaction on flowering and yield of shallots grown in the lowlands, 98 m altitude with Vertisol-type soil. The research was conducted in a randomized complete block design (RCBD) with two factors, which were varieties (V): Bima and Mentes and concentration of GA3 (C) 0 ppm, 50 ppm, 100 ppm, 150 ppm and 200 ppm and repeated three times. Varieties have significant effect (P<0.05) on plant height, leaf number, the number of bulbs per clumps, weight of fresh bulbs per clumps, and percentage of small and large bulbs produced. Bima varieties were able to flower and produced seeds, while Mentes varieties could not produce flowers and seeds. GA3 concentration have no significant effect in all of the observed component. GA3 can’t replace cold temperature for supported flowering in varieties Mentes which were planted in lowlands. There was interaction between varieties and GA3 concentration occurs in variable percentage of small and large bulbs.

Lithogeochemical character of the near-surface bedrock in the Connecticut, Housatonic, and Thames River Basins

USGS Publications Warehouse

Robinson, Gilpin R.; Peper, John D.; Steeves, Peter A.; Desimone, Leslie A.

1999-01-01

This data layer shows the generalized lithologic and geochemical (lithogeochemical) character of near-surface bedrock in the Connecticut, Housatonic, and Thames River Basins and several other small basins that drain into Long Island Sound from Connecticut. The area includes most of Connecticut, western Massachusetts, eastern Vermont, western New Hampshire, and small parts of Rhode Island, New York, and Quebec, Canada.Bedrock geologic rock units are classified into 29 lithogeochemical rock units, on the basis of the relative reactivity of their constituent minerals to dissolution and other weathering reactions and the presence of carbonate or sulfide minerals. The 29 lithogeochemical units (28 of which can be found in the study area) can be grouped into 6 major categories: (1) carbonate-rich rocks, (2) carbonate-poor, clastic sedimentary rocks restricted to distinct depositional basins, (3) metamorphosed, clastic sedimentary rocks (primarily noncalcareous), (4) mafic igneous rocks and their metamorphic equivalents, (5) ultramafic rocks, and (6) felsic igneous and plutonic rocks and their metamorphic equivalents. The lithogeochemical rock units also are grouped into nine lithologic and physiographic provinces (lithophysiographic domains), which can be further grouped into three major regions: (1) western highlands and lowlands, (2) central lowlands, and (3) eastern highlands.

Rare earth element concentrations in dissolved and acid available particulate forms for eastern UK rivers

NASA Astrophysics Data System (ADS)

Neal, C.

2007-01-01

Variations in concentration of yttrium (Y), lanthanum (La), cerium (Ce), neodymium (Nd), samarium (Sm) and gadolinium (Gd) among rivers of eastern England and the border with Scotland are described in relation to the dissolved (<0.45 µM) fraction and acid-available particulate (AAP) fractions. The rivers cover a range of rural, agricultural and urban/industrial environments. Yttrium and the lanthanides show significant levels of both dissolved and acid-available particulate forms (typically about 40% in the dissolved form). For the dissolved phase, Y and the lanthanides are linearly correlated with each other and with iron: most of this dissolved component may be in a micro-particulate/colloidal form. The Y and lanthanide relationships show marked scatter and there are anomalously high La concentrations at times for the rivers Great Ouse, Thames and Wear that are probably linked to pollutant sources. For the Ouse, and especially for one of its tributaries, the Swale, relatively high Sm concentrations are probably associated with mineralisation within the catchment and contamination of the associated flood plain. For the AAP components, there are strong linear relationships with Y and the lanthanides across all the rivers. There is also a strong link between these AAP associated REE and AAP iron, although the scatter is greater and the industrial rivers have a lower lanthanide to iron ratio, probably due to iron-rich contaminants.

From Natural to Design River Deltas

NASA Astrophysics Data System (ADS)

Giosan, Liviu

2016-04-01

Productive and biologically diverse, deltaic lowlands attracted humans since prehistory and may have spurred the emergence of the first urban civilizations. Deltas continued to be an important nexus for economic development across the world and are currently home for over half a billion people. But recently, under the double whammy of sea level rise and inland sediment capture behind dams, they have become the most threatened coastal landscape. Here I will address several deceptively simple questions to sketch some unexpected answers using example deltas from across the world from the Arctic to the Tropics, from the Danube to the Indus, Mississippi to Godavari and Krishna, Mackenzie to Yukon. What is a river delta? What is natural and what is not in a river delta? Are the geological and human histories of a delta important for its current management? Is maintaining a delta the same to building a new one? Can we design better deltas than Nature? These answers help us see clearly that survival of deltas in the next century depends on human intervention and is neither assured nor simple to address or universally applicable. Empirical observations on the hydrology, geology, biology and biochemistry of deltas are significantly lagging behind modeling capabilities endangering the applicability of numerical-based reconstruction solutions and need to be ramped up significantly and rapidly across the world.

Origin of the HIV-1 group O epidemic in western lowland gorillas.

PubMed

D'arc, Mirela; Ayouba, Ahidjo; Esteban, Amandine; Learn, Gerald H; Boué, Vanina; Liegeois, Florian; Etienne, Lucie; Tagg, Nikki; Leendertz, Fabian H; Boesch, Christophe; Madinda, Nadège F; Robbins, Martha M; Gray, Maryke; Cournil, Amandine; Ooms, Marcel; Letko, Michael; Simon, Viviana A; Sharp, Paul M; Hahn, Beatrice H; Delaporte, Eric; Mpoudi Ngole, Eitel; Peeters, Martine

2015-03-17

HIV-1, the cause of AIDS, is composed of four phylogenetic lineages, groups M, N, O, and P, each of which resulted from an independent cross-species transmission event of simian immunodeficiency viruses (SIVs) infecting African apes. Although groups M and N have been traced to geographically distinct chimpanzee communities in southern Cameroon, the reservoirs of groups O and P remain unknown. Here, we screened fecal samples from western lowland (n = 2,611), eastern lowland (n = 103), and mountain (n = 218) gorillas for gorilla SIV (SIVgor) antibodies and nucleic acids. Despite testing wild troops throughout southern Cameroon (n = 14), northern Gabon (n = 16), the Democratic Republic of Congo (n = 2), and Uganda (n = 1), SIVgor was identified at only four sites in southern Cameroon, with prevalences ranging from 0.8-22%. Amplification of partial and full-length SIVgor sequences revealed extensive genetic diversity, but all SIVgor strains were derived from a single lineage within the chimpanzee SIV (SIVcpz) radiation. Two fully sequenced gorilla viruses from southwestern Cameroon were very closely related to, and likely represent the source population of, HIV-1 group P. Most of the genome of a third SIVgor strain, from central Cameroon, was very closely related to HIV-1 group O, again pointing to gorillas as the immediate source. Functional analyses identified the cytidine deaminase APOBEC3G as a barrier for chimpanzee-to-gorilla, but not gorilla-to-human, virus transmission. These data indicate that HIV-1 group O, which spreads epidemically in west central Africa and is estimated to have infected around 100,000 people, originated by cross-species transmission from western lowland gorillas.

Origin of the HIV-1 group O epidemic in western lowland gorillas

PubMed Central

D’arc, Mirela; Ayouba, Ahidjo; Esteban, Amandine; Learn, Gerald H.; Boué, Vanina; Liegeois, Florian; Etienne, Lucie; Tagg, Nikki; Leendertz, Fabian H.; Boesch, Christophe; Madinda, Nadège F.; Robbins, Martha M.; Gray, Maryke; Cournil, Amandine; Ooms, Marcel; Letko, Michael; Simon, Viviana A.; Sharp, Paul M.; Hahn, Beatrice H.; Delaporte, Eric; Mpoudi Ngole, Eitel; Peeters, Martine

2015-01-01

HIV-1, the cause of AIDS, is composed of four phylogenetic lineages, groups M, N, O, and P, each of which resulted from an independent cross-species transmission event of simian immunodeficiency viruses (SIVs) infecting African apes. Although groups M and N have been traced to geographically distinct chimpanzee communities in southern Cameroon, the reservoirs of groups O and P remain unknown. Here, we screened fecal samples from western lowland (n = 2,611), eastern lowland (n = 103), and mountain (n = 218) gorillas for gorilla SIV (SIVgor) antibodies and nucleic acids. Despite testing wild troops throughout southern Cameroon (n = 14), northern Gabon (n = 16), the Democratic Republic of Congo (n = 2), and Uganda (n = 1), SIVgor was identified at only four sites in southern Cameroon, with prevalences ranging from 0.8–22%. Amplification of partial and full-length SIVgor sequences revealed extensive genetic diversity, but all SIVgor strains were derived from a single lineage within the chimpanzee SIV (SIVcpz) radiation. Two fully sequenced gorilla viruses from southwestern Cameroon were very closely related to, and likely represent the source population of, HIV-1 group P. Most of the genome of a third SIVgor strain, from central Cameroon, was very closely related to HIV-1 group O, again pointing to gorillas as the immediate source. Functional analyses identified the cytidine deaminase APOBEC3G as a barrier for chimpanzee-to-gorilla, but not gorilla-to-human, virus transmission. These data indicate that HIV-1 group O, which spreads epidemically in west central Africa and is estimated to have infected around 100,000 people, originated by cross-species transmission from western lowland gorillas. PMID:25733890

Preliminary Characterization of Organic Geochemistry in the Fly-Strickland River System, Papua New Guinea

NASA Astrophysics Data System (ADS)

Alin, S. R.; Aalto, R.; Remington, S. M.; Richey, J. E.

2003-12-01

The Fly-Strickland fluvial dispersal system comprises one of the largest river basins in tropical Oceania, ranking among the top 20 rivers in the world for water and sediment discharge. From the New Guinea highlands, these rivers flow >1000 km across lowland tropical floodplains to the Gulf of Papua, with an average annual depth of runoff 100 times that of the Amazon. Within the system, the Strickland has greater sediment discharge and a steeper gradient than the Fly, providing an opportunity to investigate biogeochemical differences associated with particulate flux. For eight lowland sites across the Fly-Strickland river system, we analyzed water and suspended sediment (SS) samples for an initial survey of various carbon cycle parameters. Both the Fly and Strickland Rivers were strongly supersaturated with carbon dioxide (2008-10,479 uatm CO2) and undersaturated with oxygen (1.10-5.48 mg/l O2), with the Fly having higher CO2 and lower O2 concentrations than the Strickland River. These pCO2 and O2 concentrations are comparable to and lower than (respectively) typical values in the Amazon. Measured Fly-Strickland alkalinity values fell in the range of 0.893-1.888 meq, and pH measurements were neutral to slightly alkaline (6.916-7.852). In a sample from a sediment-impoverished tributary from Lake Murray to the Strickland (Herbert R.), pH was neutral (7.060), and alkalinity and pCO2 had their lowest observed values at 0.234 meq and 1407 uatm, respectively. Nutrient concentrations were generally higher in the Strickland ([NO3]=3.36+/-0.69 uM, [PO4]=0.09+/-0.10 uM, and [Si(OH)4]=176.6+/-41.7 uM) than in the Fly River ([NO3]=1.09+/-0.04 uM, [PO4]=0.01+/-0.01 uM, and [Si(OH)4]=110.6+/-4.8 uM). NO3 and PO4 concentrations in the Fly-Strickland river system were lower than in the Amazon, and silicate was comparable. SS concentrations were higher in the Strickland than in the Fly (49.4-231.1 mg/l vs. 19.5-59.6 mg/l). Coarse particulates were organic-poor in the Fly and

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.

Stunting, adiposity, and the individual-level "dual burden" among urban lowland and rural highland Peruvian children.

PubMed

Pomeroy, Emma; Stock, Jay T; Stanojevic, Sanja; Miranda, J Jaime; Cole, Tim J; Wells, Jonathan C K

2014-01-01

The causes of the "dual burden" of stunting and obesity remain unclear, and its existence at the individual level varies between populations. We investigate whether the individual dual burden differentially affects low socioeconomic status Peruvian children from contrasting environments (urban lowlands and rural highlands), and whether tibia length can discount the possible autocorrelation between adiposity proxies and height due to height measurement error. Stature, tibia length, weight, and waist circumference were measured in children aged 3-8.5 years (n = 201). Height and body mass index (BMI) z scores were calculated using international reference data. Age-sex-specific centile curves were also calculated for height, BMI, and tibia length. Adiposity proxies (BMI z score, waist circumference-height ratio (WCHtR)) were regressed on height and also on tibia length z scores. Regression model interaction terms between site (highland vs. lowland) and height indicate that relationships between adiposity and linear growth measures differed significantly between samples (P < 0.001). Height was positively associated with BMI among urban lowland children, and more weakly with WCHtR. Among rural highland children, height was negatively associated with WCHtR but unrelated to BMI. Similar results using tibia length rather than stature indicate that stature measurement error was not a major concern. Lowland and rural highland children differ in their patterns of stunting, BMI, and WCHtR. These contrasts likely reflect environmental differences and overall environmental stress exposure. Tibia length or knee height can be used to assess the influence of measurement error in height on the relationship between stature and BMI or WCHtR. Copyright © 2014 Wiley Periodicals, Inc.

AmeriFlux CA-Gro Ontario - Groundhog River, Boreal Mixedwood Forest.

DOE Data Explorer

McCaughey, Harry [Queen's University

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site CA-Gro Ontario - Groundhog River, Boreal Mixedwood Forest.. Site Description - Groundhog River (FCRN or CCP site "ON-OMW") is situated in a typical boreal mixedwood forest in northeastern Ontario (48.217 degrees north and 82.156 degrees west) about 80 km southwest of Timmins in Reeves Twp. near the Groundhog River. Rowe (1972) places the site in the Missinaibi-Cabonga Section of the Boreal Forest Region. In terms of ecoregion and ecozone, the site is in the Lake Timiskaming Lowlands of the Boreal Shield. The forest developed after high-grade logging in the 1930's. The average age in 2013 is estimated at beteen 75 and 80 years. The forest is dominated by five species characteristic of Ontario boreal mixedwoods: trembling aspen (Populus tremuloides Michx.), black spruce (Picea mariana (Mill.) B.S.P.), white spruce (Picea glauca (Moench.) Voss.), white birch (Betula papyrifera Marsh.), and balsam fir (Abies balsamea (L.) Mill.). The surficial geology is a lacustrine deposit of varved or massive clays, silts and silty sands. The soil is an orthic gleysol with a soil moisture regime classified as fresh to very fresh. Plonski (1974) rates it as a site class 1. The topography is simple and flat with an overall elevation of 340 m ASL.

Aktywność geoturystyczna mieszkańców Niziny Południowopodlaskiej / The geotourist activity of inhabitants of the Southern Podlasie Lowland

NASA Astrophysics Data System (ADS)

Zbucki, Łukasz

2012-12-01

Southern Podlasie Lowland seems to be poor in geoturistic facilities. The conducted research on the geoturistic activity of the lowland inhabitants has indicated that the education is the determining factor. The age and place of residence seem to affect the geoturistic activity to a lesser extent

An INCA model for pathogens in rivers and catchments: Model structure, sensitivity analysis and application to the River Thames catchment, UK.

PubMed

Whitehead, P G; Leckie, H; Rankinen, K; Butterfield, D; Futter, M N; Bussi, G

2016-12-01

Pathogens are an ongoing issue for catchment water management and quantifying their transport, loss and potential impacts at key locations, such as water abstractions for public supply and bathing sites, is an important aspect of catchment and coastal management. The Integrated Catchment Model (INCA) has been adapted to model the sources and sinks of pathogens and to capture the dominant dynamics and processes controlling pathogens in catchments. The model simulates the stores of pathogens in soils, sediments, rivers and groundwaters and can account for diffuse inputs of pathogens from agriculture, urban areas or atmospheric deposition. The model also allows for point source discharges from intensive livestock units or from sewage treatment works or any industrial input to river systems. Model equations are presented and the new pathogens model has been applied to the River Thames in order to assess total coliform (TC) responses under current and projected future land use. A Monte Carlo sensitivity analysis indicates that the input coliform estimates from agricultural sources and decay rates are the crucial parameters controlling pathogen behaviour. Whilst there are a number of uncertainties associated with the model that should be accounted for, INCA-Pathogens potentially provides a useful tool to inform policy decisions and manage pathogen loading in river systems. Copyright © 2016. Published by Elsevier B.V.

Tracking spatial variation in river load from Andean highlands to inter-Andean valleys

NASA Astrophysics Data System (ADS)

Tenorio, Gustavo E.; Vanacker, Veerle; Campforts, Benjamin; Álvarez, Lenín; Zhiminaicela, Santiago; Vercruysse, Kim; Molina, Armando; Govers, Gerard

2018-05-01

Mountains play an important role in the denudation of continents and transfer erosion and weathering products to lowlands and oceans. The rates at which erosion and weathering processes take place in mountain regions have a substantial impact on the morphology and biogeochemistry of downstream reaches and lowlands. The controlling factors of physical erosion and chemical weathering and the coupling between the two processes are not yet fully understood. In this study, we report physical erosion and chemical weathering rates for five Andean catchments located in the southern Ecuadorian Andes and investigate their mutual interaction. During a 4-year monitoring period, we sampled river water at biweekly intervals, and we analyzed water samples for major ions and suspended solids. We derived the total annual dissolved, suspended sediment, and ionic loads from the flow frequency curves and adjusted rating curves and used the dissolved and suspended sediment yields as proxies for chemical weathering and erosion rates. In the 4-year period of monitoring, chemical weathering exceeds physical erosion in the high Andean catchments. Whereas physical erosion rates do not exceed 30 t km-2 y-1 in the relict glaciated morphology, chemical weathering rates range between 22 and 59 t km-2 y-1. The variation in chemical weathering is primarily controlled by intrinsic differences in bedrock lithology. Land use has no discernible impact on the weathering rate but leads to a small increase in base cation concentrations because of fertilizer leaching in surface water. When extending our analysis with published data on dissolved and suspended sediment yields from the northern and central Andes, we observe that the river load composition strongly changes in the downstream direction, indicating large heterogeneity of weathering processes and rates within large Andean basins.

Effects of global change on hydro-geomorphological hazards in Mediterranean rivers

NASA Astrophysics Data System (ADS)

Andres Lopez-Tarazon, Jose

2015-04-01

Mediterranean river basins are characterized by high (often extreme) temporal variability in precipitation, and hence discharge. Mediterranean countries are considered sensitive to so-called global change, considered as the combination of climate and land use changes. All panels on climate evolution predict future scenarios of increasing frequency and magnitude of floods and extended droughts in the Mediterranean region; both floods and droughts are likely to lead to huge geomorphic adjustments of river channels so, major metamorphosis of fluvial systems is expected as a result of global change. Water resources in the Mediterranean region is subjected to rising pressures, becoming a key issue for all governments (i.e. clear imbalance between the available water resources and the increasing water demand related to increasing human population). Such pressures are likely to give rise to major ecological and economic changes and challenges that governments need to address as a matter of priority. Changes in river flow regimes associated with global change are therefore ushering in a new era, where there is a critical need to evaluate hydro-geomorphological hazard from headwaters to lowland areas (flooding can be not just a problem related to being under the water). A key question is how our understanding of these hazards associated with global change can be improved; improvement has to come from integrated research which includes all physical conditions that influence the conveyance of water and sediments, and the river's capacity (i.e. amount of sediment) and competence (i.e. channel deformation) that, in turn, will influence physical conditions of a given point in the river network. This is the framework of the present work; it is directed to develop an integrated approach which both improves our understanding of how rivers are likely to evolve as a result of global change, and addresses the associated hazards of fluvial environmental change.

An Introduction to ESERO-UK, the UK Space Education Office

ERIC Educational Resources Information Center

Clements, Allan; Mather, Edward

2012-01-01

This article introduces the UK branch of the European Space Education Resource Office (ESERO-UK), also known as the UK Space Education Office. It is a teaching project designed to use space to enthuse primary and secondary students to study science, technology, engineering and mathematics (STEM) subjects. The office is funded by the European Space…

Formation and maintenance of single-thread tie channels entering floodplain lakes: Observations from three diverse river systems

NASA Astrophysics Data System (ADS)

Rowland, J. C.; Dietrich, W. E.; Day, G.; Parker, G.

2009-06-01

Tie channels connect rivers to floodplain lakes on many lowland rivers and thereby play a central role in floodplain sedimentology and ecology; yet they are generally unrecognized and little studied. Here we report the results of field studies focused on tie channel origin and morphodynamics in the following three contrasting systems: the Middle Fly River (Papua New Guinea), the Lower Mississippi River, and Birch Creek in Alaska. Across these river systems, tie channels vary by an order of magnitude in size but exhibit the same characteristic morphology and appear to develop and evolve by a similar set of processes. In all three systems, the channels are characterized by a narrow, leveed, single-thread morphology with maximum width approximately one tenth the width of the mainstem river. The channels typically have a V-shaped cross section, unlike most fluvial channels. These channels develop as lakes become isolated from the river by sedimentation. Narrowing of the connection between river and lake causes a sediment-laden jet to develop. Levees develop along the margins of the jet leading to channel emergence and eventual levee aggradation to the height of the mainstem levees. Bidirectional flow in these channels is common. Outflows from the lake scour sediment and prevent channel blockage. We propose that channel geometry and size are then controlled by a dynamic balance between channel narrowing by suspended sediment deposition and incision and widening by mass failure of banks during outflows. Tie channels are laterally stable and may convey flow for hundreds to a few thousand of years.

Attribution of UK Winter Floods to Anthropogenic Forcing

NASA Astrophysics Data System (ADS)

Schaller, N.; Alison, K.; Sparrow, S. N.; Otto, F. E. L.; Massey, N.; Vautard, R.; Yiou, P.; van Oldenborgh, G. J.; van Haren, R.; Lamb, R.; Huntingford, C.; Crooks, S.; Legg, T.; Weisheimer, A.; Bowery, A.; Miller, J.; Jones, R.; Stott, P.; Allen, M. R.

2014-12-01

Many regions of southern UK experienced severe flooding during the 2013/2014 winter. Simultaneously, large areas in the USA and Canada were struck by prolonged cold weather. At the time, the media and public asked whether the general rainy conditions over northern Europe and the cold weather over North America were caused by climate change. Providing an answer to this question is not trivial, but recent studies show that probabilistic event attribution is feasible. Using the citizen science project weather@home, we ran over 40'000 perturbed initial condition simulations of the 2013/2014 winter. These simulations fall into two categories: one set aims at simulating the world with climate change using observed sea surface temperatures while the second set is run with sea surface temperatures corresponding to a world that might have been without climate change. The relevant modelled variables are then downscaled by a hydrological model to obtain river flows. First results show that anthropogenic climate change led to a small but significant increase in the fractional attributable risk for 30-days peak flows for the river Thames. A single number can summarize the final result from probabilistic attribution studies indicating, for example, an increase, decrease or no change to the risk of the event occurring. However, communicating this to the public, media and other scientists remains challenging. The assumptions made in the chain of models used need to be explained. In addition, extreme events, like the UK floods of the 2013/2014 winter, are usually caused by a range of factors. While heavy precipitation events can be caused by dynamic and/or thermodynamic processes, floods occur only partly as a response to heavy precipitation. Depending on the catchment, they can be largely due to soil properties and conditions of the previous months. Probabilistic attribution studies are multidisciplinary and therefore all aspects need to be communicated properly.

Geology of the Terra Cimmeria-Utopia Planitia Highland Lowland Transitional Zone: Final Technical Approach and Scientific Results

NASA Technical Reports Server (NTRS)

Skinner, J. A., Jr.; Tanaka, K. L.

2010-01-01

The southern Utopia highland-lowland transitional zone extends from northern Terra Cimmeria to southern Utopia Planitia and contains broad, bench-like platforms with depressions, pitted cones, tholi, and lobate flows. The locally occurring geologic units and landforms contrast other transitional regions and record a spatially partitioned geologic history. We systematically delineated and described the geologic units and landforms of the southern Utopia-Cimmeria highland-lowland transitional zone for the production of a 1:1,000,000-scale geologic map (MTMs 10237, 15237, 20237, 10242, 15242, 20242, 10247, 15247, and 20247). Herein, we present technical and scientific results of this mapping project.

A Holocene sedimentary record of tectonically influenced reduced channel mobility, Skokomish River delta, Washington State, USA

NASA Astrophysics Data System (ADS)

Arcos, Maria Elizabeth Martin

2012-12-01

At the Skokomish River delta in Washington State's Puget Lowland, coseismic uplift and tilting trapped the river against a valley wall, resulting in little to no channel migration for the last 1000 years. The most recent earthquake occurred before AD 780-990, based on stratigraphic evidence such as sand blows and abrupt facies changes. Since the hypothesized tilting a 5-km-long section of the river has not migrated laterally or avulsed, resulting in reduced migration and a muddy intertidal flat that is 2 km wider in the east than on the west side of Annas Bay. A ridge running perpendicular to the river may also have restricted channel mobility. The ridge may be either the surface expression of a blind thrust fault or a relict, uplifted and tilted shoreline. The uplift and tilting of the delta can be ascribed to any of three nearby active fault zones, of which the most likely, based on the orientation of deformation, is the Saddle Mountain fault zone, which produced a surface rupture 1000-1300 years ago. The delta has experienced submergence since the earthquake. A forest that colonized an uplifted part of the delta about 800-1200 years ago was later submerged by at least 1.6 m and is now a brackish-water marsh.

Suspected macular degeneration in a captive Western lowland gorilla (Gorilla gorilla gorilla).

PubMed

Steinmetz, Andrea; Bernhard, Andreas; Sahr, Sabine; Oechtering, Gerhard

2012-09-01

The case of a 31-year-old captive female Western lowland gorilla (Gorilla gorilla gorilla) with decreased near vision but good distance vision is presented. Examination of the fundus revealed drusen-like bodies in the macula presumably because of an age-related macular degeneration (AMD). © 2012 American College of Veterinary Ophthalmologists.

Testing the Joint UK Land Environment Simulator (JULES) for flood forecasting

NASA Astrophysics Data System (ADS)

Batelis, Stamatios-Christos; Rosolem, Rafael; Han, Dawei; Rahman, Mostaquimur

2017-04-01

Land Surface Models (LSM) are based on physics principles and simulate the exchanges of energy, water and biogeochemical cycles between the land surface and lower atmosphere. Such models are typically applied for climate studies or effects of land use changes but as the resolution of LSMs and supporting observations are continuously increasing, its representation of hydrological processes need to be addressed adequately. For example, changes in climate and land use can alter the hydrology of a region, for instance, by altering its flooding regime. LSMs can be a powerful tool because of their ability to spatially represent a region with much finer resolution. However, despite such advantages, its performance has not been extensively assessed for flood forecasting simply because its representation of typical hydrological processes, such as overland flow and river routing, are still either ignored or roughly represented. In this study, we initially test the Joint UK Land Environment Simulator (JULES) as a flood forecast tool focusing on its river routing scheme. In particular, JULES river routing parameterization is based on the Rapid Flow Model (RFM) which relies on six prescribed parameters (two surface and two subsurface wave celerities, and two return flow fractions). Although this routing scheme is simple, the prescription of its six default parameters is still too generalized. Our aim is to understand the importance of each RFM parameter in a series of JULES simulations at a number of catchments in the UK for the 2006-2015 period. This is carried out, for instance, by making a number of assumptions of parameter behaviour (e.g., spatially uniform versus varying and/or temporally constant or time-varying parameters within each catchment). Hourly rainfall radar in combination with the CHESS (Climate, Hydrological and Ecological research Support System) meteorological daily data both at 1 km2 resolution are used. The evaluation of the model is based on hourly runoff

Climate and land-use changes affecting river sediment and brown trout in alpine countries--a review.

PubMed

Scheurer, Karin; Alewell, Christine; Bänninger, Dominik; Burkhardt-Holm, Patricia

2009-03-01

Catch decline of freshwater fish has been recorded in several countries. Among the possible causes, habitat change is discussed. This article focuses on potentially increased levels of fine sediments going to rivers and their effects on gravel-spawning brown trout. Indications of increased erosion rates are evident from land-use change in agriculture, changes in forest management practices, and from climate change. The latter induces an increase in air and river water temperatures, reduction in permafrost, changes in snow dynamics and an increase in heavy rain events. As a result, an increase in river sediment is likely. Suspended sediment may affect fish health and behaviour directly. Furthermore, sediment loads may clog gravel beds impeding fish such as brown trout from spawning and reducing recruitment rates. To assess the potential impact on fine sediments, knowledge of brown trout reproductive needs and the effects of sediment on brown trout health were evaluated. We critically reviewed the literature and included results from ongoing studies to answer the following questions, focusing on recent decades and rivers in alpine countries. Have climate change and land-use change increased erosion and sediment loads in rivers? Do we have indications of an increase in riverbed clogging? Are there indications of direct or indirect effects on brown trout from increased suspended sediment concentrations in rivers or from an increase in riverbed clogging? Rising air temperatures have led to more intensive precipitation in winter months, earlier snow melt in spring, and rising snow lines and hence to increased erosion. Intensification of land use has supported erosion in lowland and pre-alpine areas in the second half of the twentieth century. In the Alps, however, reforestation of abandoned land at high altitudes might reduce the erosion risk while intensification on the lower, more easily accessible slopes increases erosion risk. Data from laboratory experiments show

Fine-Scale Vertical Stratification and Guild Composition of Saproxylic Beetles in Lowland and Montane Forests: Similar Patterns despite Low Faunal Overlap

PubMed Central

Weiss, Matthias; Procházka, Jiří; Schlaghamerský, Jiří; Cizek, Lukas

2016-01-01

Objective The finer scale patterns of arthropod vertical stratification in forests are rarely studied and poorly understood. Further, there are no studies investigating whether and how altitude affects arthropod vertical stratification in temperate forests. We therefore investigated the fine-scale vertical stratification of diversity and guild structure of saproxylic beetles in temperate lowland and montane forests and compared the resulting patterns between the two habitats. Methods The beetles were sampled with flight intercept traps arranged into vertical transects (sampling heights 0.4, 1.2, 7, 14, and 21 m). A triplet of such transects was installed in each of the five sites in the lowland and in the mountains; 75 traps were used in each forest type. Results 381 species were collected in the lowlands and 236 species in the mountains. Only 105 species (21%) were found at both habitats; in the montane forest as well as in the lowlands, the species richness peaked at 1.2 m, and the change in assemblage composition was most rapid near the ground. The assemblages clearly differed between the understorey (0.4 m, 1.2 m) and the canopy (7 m, 14 m, 21 m) and between the two sampling heights within the understorey, but less within the canopy. The stratification was better pronounced in the lowland, where canopy assemblages were richer than those near the forest floor (0.4 m). In the mountains the samples from 14 and 21 m were more species poor than those from the lower heights. The guild structure was similar in both habitats. Conclusions The main patterns of vertical stratification and guild composition were strikingly similar between the montane and the lowland forest despite the low overlap of their faunas. The assemblages of saproxylic beetles were most stratified near ground. The comparisons of species richness between canopy and understorey may thus give contrasting results depending on the exact sampling height in the understorey. PMID:26978783

Flood Hazard Assessment of the coastal lowland in the Kujukuri Plain of Chiba Prefecture, Japan, using GIS and multicriteria decision analysis

NASA Astrophysics Data System (ADS)

CHEN, Huali; Tokunaga, Tomochika; Ito, Yuka; Sawamukai, Marie

2014-05-01

Floods, the most common natural disaster in the world, cause serious loss of life and economic damage. Flood is one of the disasters in the coastal lowland along the Kujukuri Plain, Chiba Prefecture, Japan. Many natural and human activities have changed the surface environment of the Plain. These include agricultural development, urban and industrial development, change of the drainage patterns of the land surface, deposition and/or erosion of the river valleys, and so on. In addition, wide spread occurrence of land subsidence has been caused by the abstraction of natural gas dissolved in groundwater. The locations of the groundwater extraction include nearby the coast, and it may increase the flood risk. Hence, it is very important to evaluate flood hazard by taking into account the temporal change of land elevation caused by land subsidence, and to develop hazard maps for protecting surface environment and land-use planning. Multicriteria decision analysis (MCDA) provides methodology and techniques for analyzing complex decision problems, which often involve incommensurable data or criteria. Also, Geographical Information System (GIS) is the powerful tool since it manages large amount of spatial data involved in MCDA. The purpose of this study is to present a flood hazard model using MCDA techniques with GIS support in a region where primary data are scare. The model incorporates six parameters: river system, topography, land-use, flood control project, passing flood from coast, and precipitation. Main data sources used are 10 meter resolution topography data, airborne laser scanning data, leveling data, Landsat-TM data, two 1:30,000 scale river watershed map, and precipitation data from precipitation observation stations around the study area. River system map was created by merging the river order, the line density, and the river sink point density layers. Land-use data were derived from Landsat-TM images. A final hazard map for 2004, as an example, was

High-resolution lidar topography of the Puget Lowland, Washington - A bonanza for earth science

USGS Publications Warehouse

Haugerud, R.A.; Harding, D.J.; Johnson, S.Y.; Harless, J.L.; Weaver, C.S.; Sherrod, B.L.

2003-01-01

More than 10,000 km2 of high-resolution, public-domain topography acquired by the Puget Sound Lidar Consortium is revolutionizing investigations of active faulting, continental glaciation, landslides, and surficial processes in the seismically active Puget Lowland. The Lowland-the population and economic center of the Pacific Northwest-presents special problems for hazards investigations, with its young glacial topography, dense forest cover, and urbanization. Lidar mapping during leaf-off conditions has led to a detailed digital model of the landscape beneath the forest canopy. The surface thus revealed contains a rich and diverse record of previously unknown surface-rupturing faults, deep-seated landslides, uplifted Holocene and Pleistocene beaches, and subglacial and periglacial features. More than half a dozen suspected postglacial fault scarps have been identified to date. Five scarps that have been trenched show evidence of large, Holocene, surface-rupturing earthquakes.

The impact of rise of the Andes and Amazon landscape evolution on diversification of lowland terra-firme forest birds

NASA Astrophysics Data System (ADS)

Aleixo, A.; Wilkinson, M. J.

2011-12-01

Since the 19th Century, the unmatched biological diversity of Amazonia has stimulated a diverse set of hypotheses accounting for patterns of species diversity and distribution in mega-diverse tropical environments. Unfortunately, the evidence supporting particular hypotheses to date is at best described as ambiguous, and no generalizations have emerged yet, mostly due to the lack of comprehensive comparative phylogeographic studies with thorough trans-Amazonian sampling of lineages. Here we report on spatial and temporal patterns of diversification estimated from mitochondrial gene trees for 31 lineages of birds associated with upland terra-firme forest, the dominant habitat in modern lowland Amazonia. The results confirm the pervasive role of Amazonian rivers as primary barriers separating sister lineages of birds, and a protracted spatio-temporal pattern of diversification, with a gradual reduction of earlier (1st and 2nd) and older (> 2 mya) splits associated with each lineage in an eastward direction (the easternmost tributaries of the Amazon, the Xingu and Tocantins Rivers, are not associated with any splits older than > 2 mya). This "younging-eastward" pattern may have an abiotic explanation related to landscape evolution. Triggered by a new pulse of Andean uplift, it has been proposed that modern Amazon basin landscapes may have evolved successively eastward, away from the mountain chain, starting ~10 mya. This process was likely based on the deposition of vast fluvial sediment masses, known as megafans, which apparently extended in series progressively eastward from Andean sources. The effects on drainage patterns are apparent from the location of axial rivers such as the Negro / Orinoco and Madeira which lie at the distal ends of major megafan ramparts at cratonic margins furthest from the Andes. Megafan extension plausibly explains the progressive extinction of the original Pebas wetland of west-central Amazonia by the present fluvial landsurfaces where

The growth response of Artemisia annua L. to organic fertilizer type in lowland

NASA Astrophysics Data System (ADS)

Prasetyo, L.; Widyastuti, Y.; Yunus, A.; Samanhudi

2018-03-01

Artemisia annua L. is a medicinal plant known in long period of time. Artemisia annua has a drug content therein, the compound is artemisinin, these compounds are useful as anti-malarial compounds. Growth of Artemisia annua L. in normal conditions is on the plateau. Planting can be done in lowland, but there is a risk that must be faced. This study was conducted to evaluate the response of the growth of the plant Artemisia annua conducted in lowland. This research was conducted at the Laboratory Jumantono of the Faculty of Agriculture, University of Sebelas Maret Surakarta. Data were analyzed using analysis of variance and if there is a significant difference continued with Duncan Multiple Range Test (DMRT) level of 5%. The results showed that the application of goat manure has a positive effect on plant height by 201.9 cm, the number of branches by 57, 30.67 ml root volume and root length of 25 cm, and weight 12.4 grams interest.

Multi-scale controls on spatial variability in river biogeochemical cycling

NASA Astrophysics Data System (ADS)

Blaen, Phillip; Kurz, Marie; Knapp, Julia; Mendoza-Lera, Clara; Lee-Cullin, Joe; Klaar, Megan; Drummond, Jennifer; Jaeger, Anna; Zarnetske, Jay; Lewandowski, Joerg; Marti, Eugenia; Ward, Adam; Fleckenstein, Jan; Datry, Thibault; Larned, Scott; Krause, Stefan

2016-04-01

Excessive nutrient concentrations are common in surface waters and groundwaters in agricultural catchments worldwide. Increasing geomorphological heterogeneity in river channels may help to attenuate nutrient pollution by facilitating water exchange fluxes with the hyporheic zone; a site of intense microbial activity where biogeochemical cycling rates can be high. However, the controls on spatial variability in biogeochemical cycling, particularly at scales relevant for river managers, are largely unknown. Here, we aimed to assess: 1) how differences in river geomorphological heterogeneity control solute transport and rates of biogeochemical cycling at sub-reach scales (102 m); and 2) the relative magnitude of these differences versus those relating to reach scale substrate variability (103 m). We used the reactive tracer resazurin (Raz), a weakly fluorescent dye that transforms to highly fluorescent resorufin (Rru) under mildly reducing conditions, as a proxy to assess rates of biogeochemical cycling in a lowland river in southern England. Solute tracer tests were conducted in two reaches with contrasting substrates: one sand-dominated and the other gravel-dominated. Each reach was divided into sub-reaches that varied in geomorphic complexity (e.g. by the presence of pool-riffle sequences or the abundance of large woody debris). Slug injections of Raz and the conservative tracer fluorescein were conducted in each reach during baseflow conditions (Q ≈ 80 L/s) and breakthrough curves monitored using in-situ fluorometers. Preliminary results indicate overall Raz:Rru transformation rates in the gravel-dominated reach were more than 50% higher than those in the sand-dominated reach. However, high sub-reach variability in Raz:Rru transformation rates and conservative solute transport parameters suggests small scale targeted management interventions to alter geomorphic heterogeneity may be effective in creating hotspots of river biogeochemical cycling and nutrient load

Linking hysteresis patterns and variations in suspended sediment sources in a highly urbanized river: a case of the River Aire, UK

NASA Astrophysics Data System (ADS)

Vercruysse, Kim; Grabowski, Robert

2017-04-01

The natural sediment balance of rivers is often disturbed as a result of increased fine sediment influx from soil erosion and/or modifications to the river channel and floodplains, causing numerous problems related to ecology, water quality, flood risk and infrastructure. It is of great importance to understand fine sediment dynamics in rivers in order to manage the problems appropriately. However, despite decades of research, our understanding of fine sediment transport is not yet sufficient to fully explain the spatial and temporal variability in sediment concentrations in rivers. To this end, the study aims to investigate the importance of sediment source variations to explain hysteresis patterns in suspended sediment transport. A sediment fingerprinting technique based on infrared spectrometry was applied in the highly urbanized River Aire catchment in northern England to identify the dominant sources of suspended sediment. Three types of potential sediment source samples were collected: soil samples from pasture in three lithological areas (limestone, millstone grit and coal measures), eroding riverbanks and urban street dust. All source samples were analyzed with Diffuse Reflectance Infrared Fourier Transform spectrometry (DRIFTS). Discriminant analysis demonstrated that the source materials could be discriminated based on their respective infrared spectra. Infrared spectra of experimental mixtures were then used to develop statistical models to estimate relative source contributions from suspended sediment samples. Suspended sediment samples were collected during a set of high flow events between 2015 and 2016, showing different hysteresis patterns between suspended sediment concentration and discharge. The fingerprinting results suggest that pasture from the limestone area is the dominant source of fine sediment. However, significant variations in source contributions during and between events are present. Small events, in terms of discharge, are marked by

Malignant hypertension and retinopathy in a western lowland gorilla (Gorilla gorilla gorilla).

PubMed

Niemuth, Jennifer N; De Voe, Ryan S; Jennings, Samuel H; Loomis, Michael R; Troan, Brigid V

2014-08-01

A 34-year-old western lowland gorilla presented with peracute blindness. Clinical evaluation, diagnostic imaging, laboratory analyses, blood pressure measurements, and necropsy were performed. The clinical and postmortem findings supported malignant hypertension. We describe a case of naturally occurring hypertensive encephalopathy and retinopathy in a gorilla. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Trends in evaporation loss over the UK: 1962 to 2013

NASA Astrophysics Data System (ADS)

Blyth, Eleanor; Robinson, Emma; Martinez de la Torre, Alberto

2017-04-01

Many models of hydrology assume that an increase in air temperature will result in an increase in evaporation. However, there are some processes involved in transpiration (evaporation through the vegetation) that make the relationship more complicated: in a bid to conserve water, vegetation will reduce their stomata in response to drier soils and warmer drier air which leads to lower transpiration rates despite higher evaporative demands. In addition, the vegetation responds to increases in atmospheric carbon dioxide by closing their stomata, and this further reduces the transpiration. The JULES (Joint UK Land Environment Simulator) model, used widely in the UK to study the impacts of climate change on the environment, includes many of the processes that are likely to affect changes in water loss and its impact on large scale hydrology. A new assessment of the UK wide water balance for the last 52 years (1961 to 2013) at a 1km grid-scale has been made using this model in a system called CHESS (Climate Hydrology and Ecology research Support System). Some data is available to check the overall water balance. For instance, river flow data can be used at an annual time scale to capture the water balance, while evaporation data from flux towers can be used at some locations around the UK for the few years that it is available to evaluate the seasonal variations of evaporation. Both of these methods provide imperfect but useful evidence. Here we present the results of the modelling exercise and the evaluation: long term increasing evaporation loss trends are clearly present in the model output and these are discussed with respect to the different drivers of change.

Short-term adaptation and chronic cardiac remodelling to high altitude in lowlander natives and Himalayan Sherpa.

PubMed

Stembridge, Mike; Ainslie, Philip N; Shave, Rob

2015-11-01

What is the topic of this review? At high altitude, the cardiovascular system must adapt in order to meet the metabolic demand for oxygen. This review summarizes recent findings relating to short-term and life-long cardiac adaptation to high altitude in the context of exercise capacity. What advances does it highlight? Both Sherpa and lowlanders exhibit smaller left ventricular volumes at high altitude; however, myocardial relaxation, as evidenced by diastolic untwist, is reduced only in Sherpa, indicating that short-term hypoxia does not impair diastolic relaxation. Potential remodelling of systolic function, as evidenced by lower left ventricular systolic twist in Sherpa, may facilitate the requisite sea-level mechanical reserve required during exercise, although this remains to be confirmed. Both short-term and life-long high-altitude exposure challenge the cardiovascular system to meet the metabolic demand for O2 in a hypoxic environment. As the demand for O2 delivery increases during exercise, the circulatory component of oxygen transport is placed under additional stress. Acute adaptation and chronic remodelling of cardiac structure and function may occur to facilitate O2 delivery in lowlanders during sojourn to high altitude and in permanent highland residents. However, our understanding of cardiac structural and functional adaption in Sherpa remains confined to a higher maximal heart rate, lower pulmonary vascular resistance and no differences in resting cardiac output. Ventricular form and function are intrinsically linked through the left ventricular (LV) mechanics that facilitate efficient ejection, minimize myofibre stress during contraction and aid diastolic recoil. Recent examination of LV mechanics has allowed detailed insight into fundamental cardiac adaptation in high-altitude Sherpa. In this symposium report, we review recent advances in our understanding of LV function in both lowlanders and Sherpa at rest and discuss the potential consequences

The oxygen isotopic composition of phosphate in river water and its potential sources in the Upper River Taw catchment, UK.

PubMed

Granger, Steven J; Heaton, Tim H E; Pfahler, Verena; Blackwell, Martin S A; Yuan, Huimin; Collins, Adrian L

2017-01-01

The need to reduce both point and diffuse phosphorus pollution to aquatic ecosystems is widely recognised and in order to achieve this, identification of the different pollutant sources is essential. Recently, a stable isotope approach using oxygen isotopes within phosphate (δ 18 O PO4 ) has been used in phosphorus source tracing studies. This approach was applied in a one-off survey in September 2013 to the River Taw catchment in south-west England where elevated levels of phosphate have been reported. River water δ 18 O PO4 along the main channel varied little, ranging from +17.1 to +18.8‰. This was no >0.3‰ different to that of the isotopic equilibrium with water (Eδ 18 O PO4 ). The δ 18 O PO4 in the tributaries was more variable (+17.1 to +18.8‰), but only deviated from Eδ 18 O PO4 by between 0.4 and 0.9‰. Several potential phosphate sources within the catchment were sampled and most had a narrow range of δ 18 O PO4 values similar to that of river Eδ 18 O PO4 . Discharge from two waste water treatment plants had different and distinct δ 18 O PO4 from one another ranging between +16.4 and +19.6‰ and similar values to that of a dairy factory final effluent (+16.5 to +17.8‰), mains tap water (+17.8 to +18.4‰), and that of the phosphate extracted from river channel bed sediment (+16.7 to +17.6‰). Inorganic fertilizers had a wide range of values (+13.3 to +25.9‰) while stored animal wastes were consistently lower (+12.0 to +15.0‰) than most other sources and Eδ 18 O PO4 . The distinct signals from the waste water treatment plants were lost within the river over a short distance suggesting that rapid microbial cycling of phosphate was occurring, because microbial cycling shifts the isotopic signal towards Eδ 18 O PO4 . This study has added to the global inventory of phosphate source δ 18 O PO4 values, but also demonstrated the limitations of this approach to identifying phosphate sources, especially at times when microbial cycling is

Widespread Forest Vertebrate Extinctions Induced by a Mega Hydroelectric Dam in Lowland Amazonia

PubMed Central

2015-01-01

Mega hydropower projects in tropical forests pose a major emergent threat to terrestrial and freshwater biodiversity worldwide. Despite the unprecedented number of existing, under-construction and planned hydroelectric dams in lowland tropical forests, long-term effects on biodiversity have yet to be evaluated. We examine how medium and large-bodied assemblages of terrestrial and arboreal vertebrates (including 35 mammal, bird and tortoise species) responded to the drastic 26-year post-isolation history of archipelagic alteration in landscape structure and habitat quality in a major hydroelectric reservoir of Central Amazonia. The Balbina Hydroelectric Dam inundated 3,129 km2 of primary forests, simultaneously isolating 3,546 land-bridge islands. We conducted intensive biodiversity surveys at 37 of those islands and three adjacent continuous forests using a combination of four survey techniques, and detected strong forest habitat area effects in explaining patterns of vertebrate extinction. Beyond clear area effects, edge-mediated surface fire disturbance was the most important additional driver of species loss, particularly in islands smaller than 10 ha. Based on species-area models, we predict that only 0.7% of all islands now harbor a species-rich vertebrate assemblage consisting of ≥80% of all species. We highlight the colossal erosion in vertebrate diversity driven by a man-made dam and show that the biodiversity impacts of mega dams in lowland tropical forest regions have been severely overlooked. The geopolitical strategy to deploy many more large hydropower infrastructure projects in regions like lowland Amazonia should be urgently reassessed, and we strongly advise that long-term biodiversity impacts should be explicitly included in pre-approval environmental impact assessments. PMID:26132139

Widespread Forest Vertebrate Extinctions Induced by a Mega Hydroelectric Dam in Lowland Amazonia.

PubMed

Benchimol, Maíra; Peres, Carlos A

2015-01-01

Mega hydropower projects in tropical forests pose a major emergent threat to terrestrial and freshwater biodiversity worldwide. Despite the unprecedented number of existing, under-construction and planned hydroelectric dams in lowland tropical forests, long-term effects on biodiversity have yet to be evaluated. We examine how medium and large-bodied assemblages of terrestrial and arboreal vertebrates (including 35 mammal, bird and tortoise species) responded to the drastic 26-year post-isolation history of archipelagic alteration in landscape structure and habitat quality in a major hydroelectric reservoir of Central Amazonia. The Balbina Hydroelectric Dam inundated 3,129 km2 of primary forests, simultaneously isolating 3,546 land-bridge islands. We conducted intensive biodiversity surveys at 37 of those islands and three adjacent continuous forests using a combination of four survey techniques, and detected strong forest habitat area effects in explaining patterns of vertebrate extinction. Beyond clear area effects, edge-mediated surface fire disturbance was the most important additional driver of species loss, particularly in islands smaller than 10 ha. Based on species-area models, we predict that only 0.7% of all islands now harbor a species-rich vertebrate assemblage consisting of ≥80% of all species. We highlight the colossal erosion in vertebrate diversity driven by a man-made dam and show that the biodiversity impacts of mega dams in lowland tropical forest regions have been severely overlooked. The geopolitical strategy to deploy many more large hydropower infrastructure projects in regions like lowland Amazonia should be urgently reassessed, and we strongly advise that long-term biodiversity impacts should be explicitly included in pre-approval environmental impact assessments.

Understanding drought propagation in the UK in the context of climatology and catchment properties

NASA Astrophysics Data System (ADS)

Barker, Lucy; Hannaford, Jamie; Bloomfield, John; Marchant, Ben

2017-04-01

Droughts are a complex natural phenomena that are challenging to plan and prepare for. The propagation of droughts through the hydrological cycle is one of many factors which contribute to this complexity, and a thorough understanding of drought propagation is crucial for informed drought management, particularly in terms of water resources management in both the short and long term. Previous studies have found that both climatological and catchment factors cause lags in drought propagation from meteorological to hydrological and hydrogeological droughts. There are strong gradients in both climatology and catchment properties across the UK. Catchments in the north and west of the UK are relatively impermeable, upland catchments with thin soils and receive the highest annual precipitation with relatively low mean annual temperatures. Conversely, in the south and east of the UK, characterised by higher mean temperatures and lower annual precipitation, catchments are underlain by a number of major aquifers (e.g. Chalk, limestone) and are typically associated with high baseflow rivers. Here we explore the effects of these gradients in climatology and catchments on the propagation of droughts. Using standardised drought indices (the Standardised Precipitation Index; the Standardised Streamflow Index; and the Standardised Groundwater Index) we analyse drought propagation characteristics for selected catchment-borehole pairs across the UK using reconstructed time series back to the 19th century. We investigate how the timing, nature and predictability of drought propagation changes across the UK, given gradients in climatology and catchment characteristics. We use probability of detection methods, usually used for forecast verification, to investigate how well precipitation and streamflow deficits predict deficits in streamflow and groundwater levels and how this varies across the UK.

A reassessment of the suspended sediment load in the Madeira River basin from the Andes of Peru and Bolivia to the Amazon River in Brazil, based on 10 years of data from the HYBAM monitoring programme

NASA Astrophysics Data System (ADS)

Vauchel, Philippe; Santini, William; Guyot, Jean Loup; Moquet, Jean Sébastien; Martinez, Jean Michel; Espinoza, Jhan Carlo; Baby, Patrice; Fuertes, Oscar; Noriega, Luis; Puita, Oscar; Sondag, Francis; Fraizy, Pascal; Armijos, Elisa; Cochonneau, Gérard; Timouk, Franck; de Oliveira, Eurides; Filizola, Naziano; Molina, Jorge; Ronchail, Josyane

2017-10-01

The Madeira River is the second largest tributary of the Amazon River. It contributes approximately 13% of the Amazon River flow and it may contribute up to 50% of its sediment discharge to the Atlantic Ocean. Until now, the suspended sediment load of the Madeira River was not well known and was estimated in a broad range from 240 to 715 Mt yr-1. Since 2002, the HYBAM international network developed a new monitoring programme specially designed to provide more reliable data than in previous intents. It is based on the continuous monitoring of a set of 11 gauging stations in the Madeira River watershed from the Andes piedmont to the confluence with the Amazon River, and discrete sampling of the suspended sediment concentration every 7 or 10 days. This paper presents the results of the suspended sediment data obtained in the Madeira drainage basin during 2002-2011. The Madeira River suspended sediment load is estimated at 430 Mt yr-1 near its confluence with the Amazon River. The average production of the Madeira River Andean catchment is estimated at 640 Mt yr-1 (±30%), the corresponding sediment yield for the Andes is estimated at 3000 t km-2 yr-1 (±30%), and the average denudation rate is estimated at 1.20 mm yr-1 (±30%). Contrary to previous results that had mentioned high sedimentation rates in the Beni River floodplain, we detected no measurable sedimentation process in this part of the basin. On the Mamoré River basin, we observed heavy sediment deposition of approximately 210 Mt yr-1 that seem to confirm previous studies. But while these studies mentioned heavy sedimentation in the floodplain, we showed that sediment deposition occurred mainly in the Andean piedmont and immediate foreland in rivers (Parapeti, Grande, Pirai, Yapacani, Chimoré, Chaparé, Secure, Maniqui) with discharges that are not sufficiently large to transport their sediment load downstream in the lowlands.

Balancing Riparian Management and River Recreation: Methods and Applications for Exploring Floater Behavior and Their Interaction with Large Wood

NASA Astrophysics Data System (ADS)

Biedenweg, Kelly; Akyuz, Kate; Skeele, Rebecca

2012-08-01

River managers are tasked with meeting both ecological and human needs. In the Puget Sound lowland, riparian management often includes placing or allowing the presence of large wood to stabilize riverbanks and enhance salmon habitat. Although this practice benefits humans by protecting infrastructure and natural resources, it is unclear how such practices interact with an additional human interest, recreation. Furthermore, we were unable to find studies that describe how an agency can go about researching the interaction between recreation and large wood management practices. This study tested methods for describing and estimating the number of river floaters, where they float in relationship to river projects, the risks they take while floating, and their perceptions of large wood in the river. Selecting a high-use suburban river in Washington State, we used riverside observations, interviews, and an infrared counter to gather data in the summer of 2010. Statistical analyses provided general characteristics of users, trends in engaging in risky behaviors, and estimates of use for the entire season and on the busiest day. Data mapping with GIS presented the density of use along the river and frequency of use of specific float routes. Finally, qualitative analysis of interviews clarified floaters' perspectives of large wood. To address the multiple mandates of river managers, it is important to understand recreation users, the factors that could be putting them at risk, and how the actual users perceive large wood in the river. This study demonstrates methods for scientifically gathering such information and applying it when making riparian management decisions.

Probabilistic properties of the date of maximum river flow, an approach based on circular statistics in lowland, highland and mountainous catchment

NASA Astrophysics Data System (ADS)

Rutkowska, Agnieszka; Kohnová, Silvia; Banasik, Kazimierz

2018-04-01

Probabilistic properties of dates of winter, summer and annual maximum flows were studied using circular statistics in three catchments differing in topographic conditions; a lowland, highland and mountainous catchment. The circular measures of location and dispersion were used in the long-term samples of dates of maxima. The mixture of von Mises distributions was assumed as the theoretical distribution function of the date of winter, summer and annual maximum flow. The number of components was selected on the basis of the corrected Akaike Information Criterion and the parameters were estimated by means of the Maximum Likelihood method. The goodness of fit was assessed using both the correlation between quantiles and a version of the Kuiper's and Watson's test. Results show that the number of components varied between catchments and it was different for seasonal and annual maxima. Differences between catchments in circular characteristics were explained using climatic factors such as precipitation and temperature. Further studies may include circular grouping catchments based on similarity between distribution functions and the linkage between dates of maximum precipitation and maximum flow.

Hominin footprints from early Pleistocene deposits at Happisburgh, UK.

PubMed

Ashton, Nick; Lewis, Simon G; De Groote, Isabelle; Duffy, Sarah M; Bates, Martin; Bates, Richard; Hoare, Peter; Lewis, Mark; Parfitt, Simon A; Peglar, Sylvia; Williams, Craig; Stringer, Chris

2014-01-01

Investigations at Happisburgh, UK, have revealed the oldest known hominin footprint surface outside Africa at between ca. 1 million and 0.78 million years ago. The site has long been recognised for the preservation of sediments containing Early Pleistocene fauna and flora, but since 2005 has also yielded humanly made flint artefacts, extending the record of human occupation of northern Europe by at least 350,000 years. The sediments consist of sands, gravels and laminated silts laid down by a large river within the upper reaches of its estuary. In May 2013 extensive areas of the laminated sediments were exposed on the foreshore. On the surface of one of the laminated silt horizons a series of hollows was revealed in an area of ca. 12 m(2). The surface was recorded using multi-image photogrammetry which showed that the hollows are distinctly elongated and the majority fall within the range of juvenile to adult hominin foot sizes. In many cases the arch and front/back of the foot can be identified and in one case the impression of toes can be seen. Using foot length to stature ratios, the hominins are estimated to have been between ca. 0.93 and 1.73 m in height, suggestive of a group of mixed ages. The orientation of the prints indicates movement in a southerly direction on mud-flats along the river edge. Early Pleistocene human fossils are extremely rare in Europe, with no evidence from the UK. The only known species in western Europe of a similar age is Homo antecessor, whose fossil remains have been found at Atapuerca, Spain. The foot sizes and estimated stature of the hominins from Happisburgh fall within the range derived from the fossil evidence of Homo antecessor.

Spatial and Temporal Distribution of Particulate Organic Carbon in the Winisk River, Northern Ontario

NASA Astrophysics Data System (ADS)

Glasauer, S.; Smith, P.; Smith, R. W.

2016-12-01

The Winisk River begins in the Precambrian rock of the Canadian Shield in Ontario and traverses the Hudson Bay Lowlands before terminating in Hudson Bay. It drains an area of 67,300 km2that is sparsely populated, with remote communities that depend on natural resources. Accelerated decomposition of organic carbon (OC) in the area due to climate change is supported by higher inputs of particulate and dissolved OC to surface waters (Amon et al, 2012). The Winisk River is a particularly important source of OC to Hudson Bay, shown by high rates of lignin accumulation near the mouth of the river (Kuzyk et al., 2008). Webequie First Nation (WFN) is a small community located on Eastwood Island in Winisk Lake. It is the closest community to the proposed massive development of the "Ring of Fire" chromite and other mineral deposits in the James Bay Lowlands. Mine-related developments can be expected to impact water flows, water chemistry, and carbon cycling in the region. We sampled water and sediment at the major inlets to the lake and at the northern outlet within the territorial boundaries to characterize water chemistry, relate lignin compositional patterns to C and N isotopic signatures, and interpret temporal patterns in advance of development and future climate change. Organic C in the sediments ranged from around 1% to around 30%. Samples were analyzed for lignin compounds using a CuO digestion method coupled to GC-MS to identify lignin-phenol monomers, benzoic acids, and p-hydroxy acid. Ratios of 3,5-dihydroxybenzoic acid, P-hydroxy phenols and cinnamyl phenols to total vanillyl phenols indicate that gymnosperm wood and sphagnum peat dominate the OC pool, although the proportions of gymnosperm- and sphagnum-derived material vary between sites. Stable isotope analysis (δ13C, δ15N) suggests that other inputs of OC may be present that are consistent with OM derived from the erosion of older marine sediments. The results support that the proportion of sphagnum mosses

The effects of hydraulic works and wetlands function in the Salado-River basin (Buenos Aires, Argentina).

PubMed

Bazzuri, M E; Gabellone, N A; Solari, L C

2018-01-26

Man-made activities exert great influences on fluvial ecosystems, with lowland rivers being substantially modified through agricultural land use and populations. The recent construction of drainage canals in the upper stretch of the Salado-River basin caused the mobilization of huge amounts of salts formerly stored in the groundwater. The main aim of this work was to analyze the effect of the discharges of those canals into the Salado-River water, under different hydrologic conditions, and the role of the wetlands and shallow lakes placed along the canals' system. Physicochemical variables were measured and water samples were taken during times of high water, mean flows, drought, and extreme drought. The environmental variables and the plankton development were related to the hydrologic regime and reached minimum values during floods because of low temperatures and dilution. Local effects on the water's ionic composition became pronounced during droughts because of groundwater input. Nutrient concentrations were mainly associated with point wastewater discharges. Conductivity, ion concentrations, total plankton biomass, and species richness increased in the Salado-River downstream site, after the canals' discharges. The artificial-drainage system definitely promotes the incorporation of salts into the Salado-River basin. In this scenario, a careful hydraulic management is needed to take into account this issue of secondary salinization that threatens the economic exploitation of the region. The wetlands present in this study acted as service environments not only helping to reduce salt, nutrient, and suspended-solid concentrations downstream but also contributing a plethora of species and plankton biomass into the Salado-River main course.

Snow mass and river flows modelled using GRACE total water storage observations

NASA Astrophysics Data System (ADS)

Wang, S.

2017-12-01

Snow mass and river flow measurements are difficult and less accurate in cold regions due to the hash environment. Floods in cold regions are commonly a result of snowmelt during the spring break-up. Flooding is projected to increase with climate change in many parts of the world. Forecasting floods from snowmelt remains a challenge due to scarce and quality issues in basin-scale snow observations and lack of knowledge for cold region hydrological processes. This study developed a model for estimating basin-level snow mass (snow water equivalent SWE) and river flows using the total water storage (TWS) observations from the Gravity Recovery and Climate Experiment (GRACE) satellite mission. The SWE estimation is based on mass balance approach which is independent of in situ snow gauge observations, thus largely eliminates the limitations and uncertainties with traditional in situ or remote sensing snow estimates. The model forecasts river flows by simulating surface runoff from snowmelt and the corresponding baseflow from groundwater discharge. Snowmelt is predicted using a temperature index model. Baseflow is predicted using a modified linear reservoir model. The model also quantifies the hysteresis between the snowmelt and the streamflow rates, or the lump time for water travel in the basin. The model was applied to the Red River Basin, the Mackenzie River Basin, and the Hudson Bay Lowland Basins in Canada. The predicted river flows were compared with the observed values at downstream hydrometric stations. The results were also compared to that for the Lower Fraser River obtained in a separate study to help better understand the roles of environmental factors in determining flood and their variations with different hydroclimatic conditions. This study advances the applications of space-based time-variable gravity measurements in cold region snow mass estimation, river flow and flood forecasting. It demonstrates a relatively simple method that only needs GRACE TWS

BIOGENIC VOLATILE ORGANIC COMPOUND EMISSIONS FROM A LOWLAND TROPICAL WET FOREST IN COSTA RICA

EPA Science Inventory

Twenty common plant species were screened for emissions of biogenic volatile organic compounds (BVOCS) at a lowland tropical wet forest site in Costa Rica. Ten of the species. examined emitted substantial quantities of isoprene. These species accounted for 35-50% of the total bas...

Interbasin groundwater flow and groundwater interaction with surface water in a lowland rainforest, Costa Rica: A review

NASA Astrophysics Data System (ADS)

Genereux, David P.; Jordan, Michael

2006-04-01

This paper reviews work related to interbasin groundwater flow (naturally occurring groundwater flow beneath watershed topographic divides) into lowland rainforest watersheds at La Selva Biological Station in Costa Rica. Chemical mixing calculations (based on dissolved chloride) have shown that up to half the water in some streams and up to 84% of the water in some riparian seeps and wells is due to high-solute interbasin groundwater flow (IGF). The contribution is even greater for major ions; IGF accounts for well over 90% of the major ions at these sites. Proportions are highly variable both among watersheds and with elevation within the same watershed (there is greater influence of IGF at lower elevations). The large proportion of IGF found in water in some riparian wetlands suggests that IGF is largely responsible for maintaining these wetlands. δ 18O data support the conclusions from the major ion data. Annual water and major ion budgets for two adjacent watersheds, one affected by IGF and the other not, showed that IGF accounted for two-thirds of the water input and 92-99% of the major ion input (depending on the major ion in question) to the former watershed. The large (in some cases, dominating) influence of IGF on watershed surface water quantity and quality has important implications for stream ecology and watershed management in this lowland rainforest. Because of its high phosphorus content, IGF increases a variety of ecological variables (algal growth rates, leaf decay rate, fungal biomass, invertebrate biomass, microbial respiration rates on leaves) in streams at La Selva. The significant rates of IGF at La Selva also suggest the importance of regional (as opposed to small-scale local) water resource planning that links lowland watersheds with regional groundwater. IGF is a relatively unexplored and potentially critical factor in the conservation of lowland rainforest.

Cultural Phylogenetics of the Tupi Language Family in Lowland South America

PubMed Central

Walker, Robert S.; Wichmann, Søren; Mailund, Thomas; Atkisson, Curtis J.

2012-01-01

Background Recent advances in automated assessment of basic vocabulary lists allow the construction of linguistic phylogenies useful for tracing dynamics of human population expansions, reconstructing ancestral cultures, and modeling transition rates of cultural traits over time. Methods Here we investigate the Tupi expansion, a widely-dispersed language family in lowland South America, with a distance-based phylogeny based on 40-word vocabulary lists from 48 languages. We coded 11 cultural traits across the diverse Tupi family including traditional warfare patterns, post-marital residence, corporate structure, community size, paternity beliefs, sibling terminology, presence of canoes, tattooing, shamanism, men's houses, and lip plugs. Results/Discussion The linguistic phylogeny supports a Tupi homeland in west-central Brazil with subsequent major expansions across much of lowland South America. Consistently, ancestral reconstructions of cultural traits over the linguistic phylogeny suggest that social complexity has tended to decline through time, most notably in the independent emergence of several nomadic hunter-gatherer societies. Estimated rates of cultural change across the Tupi expansion are on the order of only a few changes per 10,000 years, in accord with previous cultural phylogenetic results in other language families around the world, and indicate a conservative nature to much of human culture. PMID:22506065

Umbrisols at Lower Altitudes, Case Study from Borská lowland (Slovakia)

NASA Astrophysics Data System (ADS)

Jenčo, Marián; Matečný, Igor; Putiška, René; Burian, Libor; Tančárová, Kristína; Kušnirák, Dávid

2018-05-01

Umbrisols generally develop in a cool and humid climate. Therefore, occurrence of these soils in the Borská lowland of southwestern Slovakia is very uncommon, and this inspired the aim of this paper: Analysis of the natural conditions suitable for Umbrisol development. Umbrisols in the Borská lowland developed from aeolian quartz sands accumulated on Neogenne marine clay sediments. Their occurrence is connected with the groundwater table relatively close to the ground surface and this particularly determines Umbrisol genesis in this area. Sufficient input via organic matter is an important factor for formation of the umbric horizon, and only the rich herbaceous undergrowth of the prevailing planted pine and mixed pine-oak forests is capable of providing it. A growth of diep-rooted grass is closely connected with higher soil moisture content, and quite moist areas occur in the deeper inter-dunes depressions. Constant soil moisture in these sites is facilitated by water capillary elevation. While Umbrisols are transformed to Arenosols at increased altitude, they can be transformed to Gleysols in deep depressions. Herein, induced polarization provided suitable geophysical method for detection of arenic Umbrisol inclusions. Sharp transformation of the humus layer to dry non-polarized aeolian quartz sands enabled the surface horizon to be distinguished by induced polarization

Land Management, River Restoration and the Water Framework Directive

NASA Astrophysics Data System (ADS)

Smith, Ben; Clifford, Nicholas

2014-05-01

The influence of catchment land-use on river ecosystems is well established, with negative changes in hydrology, sediment supply and pollutants causing widespread degradation in modified catchments across Europe. The strength of relationship found between different land-use types and impacts on river systems varies from study to study as a result of issues around data quality, scale, study design and the interaction of stressors at multiple scales. Analysis of large-scale datasets can provide important information about the way that catchments pressures affect WFD objectives at a national scale. Comparisons of relationships between land-use and WFD status in different types of catchment within the UK allow an assessment of catchment sensitivity and analysis of the catchment characteristics which influence these relationships. The results suggest prioritising catchments at or near land-use thresholds, or targeting waterbodies with limited land-use pressures but which are failing to achieve GES or GEP. This paper uses UK datasets on land cover and WFD waterbody status to examine how catchment land-use impacts on WFD status and to evaluate opportunities to achieve Good Ecological Status or Good Ecological Potential. Agricultural and urban land-use are shown to have different types of relationship with respect to the likelihood of achieving Good Ecological Status, and with clear threshold effects apparent for urban land-use in the catchment. Broad-scale analysis shows the influence of different sized buffer strips in mitigating the negative effects of different types of land-cover, and reinforces the positive effects of riparian woodland on river ecosystems and their potential under the WFD.

Associations between trematode infections in cattle and freshwater snails in highland and lowland areas of Iringa Rural District, Tanzania.

PubMed

Nzalawahe, Jahashi; Kassuku, Ayub A; Stothard, J Russell; Coles, Gerald C; Eisler, Mark C

2015-09-01

The epidemiology of trematode infections in cattle was investigated within highland and lowland areas of Iringa Rural District, in southern Tanzania. Fecal samples were collected from 450 cattle in 15 villages at altitudes ranging from 696 to 1800 m above the sea level. Freshwater snails were collected from selected water bodies and screened for emergence of cercariae. The infection rates in cattle were Fasciola gigantica 28·2%, paramphistomes 62·8% and Schistosoma bovis 4·8%. Notably, prevalence of trematode infections in cattle was much higher in highland (altitude > 1500 m) as compared with lowland (altitude < 1500 m) areas and was statistically significant (P-value = 0·000) for F. gigantica and paramphistomes but not for S. bovis. The snails collected included Lymnaea natalensis, Bulinus africanus, Bulinus tropicus, Bulinus forskali, Biomphalaria pfeifferi, Melanoides tuberculata and Bellamya constricta with a greater proportion of highland (75%) than lowland (36%) water bodies harbouring snails. Altitude is a major factor shaping the epidemiology of F. gigantica and paramphistomes infections in cattle in Iringa Rural District with greater emphasis upon control needed in highland areas.

Hydrologic reconnaissance of the Noatak River basin, Alaska, 1978

USGS Publications Warehouse

Childers, Joseph M.; Kernodle, Donald R.

1981-01-01

Hydrologic data were collected in 1978 described water resources of the Noatak River basin, Alaska. Streamflow varies seasonally. No flow was observed from the upper part of the basin in late winter (April). In the lower part of the basin springs support perennial flow in the Kugururok River and downstream along the Noatak. The discharge of the Noatak was 150 cubic feet per second in April 1978. During the summer, rainstorms are common, and runoff produces high flow. During August 1978, flow was normal in the basin; unit runoff averaged about 1 cubic foot per second per square mile. The Noatak is a gravel-bed stream of moderate slope. It drops about 1,800 feet in elevation from a point near the head waters to the mouth, a distance of 400 miles. Streambed material in most places is gravel, cobbles, and boulders, maximum riffle depths and pool widths increase in a downstream direction. Stream velocity in August 1978 increased from about 1 foot per second in the upper basin to about 4 feet per second in the lower reaches. High-water marks of the maximum evident flood were found at elevations from bankfull to 5 feet above bankfull. Maximum evident flood unit runoff rates were estimated to be less than 50 cubic feet per second per square mile. Scars produced by ice jams were seldom seen above bankfull. Bank erosion appears to be most active in the lowlands. Water in the Noatak River basin is virtually unaffected by man 's activity. Water quality varies with location, weather, season, and source; the water is normally clear, cool, and hard. During late winter sea water intrudes into the Lower Noatak Canyon. Benthic invertebrate community composition and variability suggest the river 's undiminished natural quality. (USGS)

PLAB and UK graduates' performance on MRCP(UK) and MRCGP examinations: data linkage study.

PubMed

McManus, I C; Wakeford, Richard

2014-04-17

To assess whether international medical graduates passing the two examinations set by the Professional and Linguistic Assessments Board (PLAB1 and PLAB2) of the General Medical Council (GMC) are equivalent to UK graduates at the end of the first foundation year of medical training (F1), as the GMC requires, and if not, to assess what changes in the PLAB pass marks might produce equivalence. Data linkage of GMC PLAB performance data with data from the Royal Colleges of Physicians and the Royal College of General Practitioners on performance of PLAB graduates and UK graduates at the MRCP(UK) and MRCGP examinations. Doctors in training for internal medicine or general practice in the United Kingdom. 7829, 5135, and 4387 PLAB graduates on their first attempt at MRCP(UK) Part 1, Part 2, and PACES assessments from 2001 to 2012 compared with 18,532, 14,094, and 14,376 UK graduates taking the same assessments; 3160 PLAB1 graduates making their first attempt at the MRCGP AKT during 2007-12 compared with 14,235 UK graduates; and 1411 PLAB2 graduates making their first attempt at the MRCGP CSA during 2010-12 compared with 6935 UK graduates. Performance at MRCP(UK) Part 1, Part 2, and PACES assessments, and MRCGP AKT and CSA assessments in relation to performance on PLAB1 and PLAB2 assessments, as well as to International English Language Testing System (IELTS) scores. MRCP(UK), MRCGP, and PLAB results were analysed as marks relative to the pass mark at the first attempt. PLAB1 marks were a valid predictor of MRCP(UK) Part 1, MRCP(UK) Part 2, and MRCGP AKT (r=0.521, 0.390, and 0.490; all P<0.001). PLAB2 marks correlated with MRCP(UK) PACES and MRCGP CSA (r=0.274, 0.321; both P<0.001). PLAB graduates had significantly lower MRCP(UK) and MRCGP assessments (Glass's Δ=0.94, 0.91, 1.40, 1.01, and 1.82 for MRCP(UK) Part 1, Part 2, and PACES and MRCGP AKT and CSA), and were more likely to fail assessments and to progress more slowly than UK medical graduates. IELTS scores correlated

PLAB and UK graduates’ performance on MRCP(UK) and MRCGP examinations: data linkage study

PubMed Central

Wakeford, Richard

2014-01-01

Objectives To assess whether international medical graduates passing the two examinations set by the Professional and Linguistic Assessments Board (PLAB1 and PLAB2) of the General Medical Council (GMC) are equivalent to UK graduates at the end of the first foundation year of medical training (F1), as the GMC requires, and if not, to assess what changes in the PLAB pass marks might produce equivalence. Design Data linkage of GMC PLAB performance data with data from the Royal Colleges of Physicians and the Royal College of General Practitioners on performance of PLAB graduates and UK graduates at the MRCP(UK) and MRCGP examinations. Setting Doctors in training for internal medicine or general practice in the United Kingdom. Participants 7829, 5135, and 4387 PLAB graduates on their first attempt at MRCP(UK) Part 1, Part 2, and PACES assessments from 2001 to 2012 compared with 18 532, 14 094, and 14 376 UK graduates taking the same assessments; 3160 PLAB1 graduates making their first attempt at the MRCGP AKT during 2007-12 compared with 14 235 UK graduates; and 1411 PLAB2 graduates making their first attempt at the MRCGP CSA during 2010-12 compared with 6935 UK graduates. Main outcome measures Performance at MRCP(UK) Part 1, Part 2, and PACES assessments, and MRCGP AKT and CSA assessments in relation to performance on PLAB1 and PLAB2 assessments, as well as to International English Language Testing System (IELTS) scores. MRCP(UK), MRCGP, and PLAB results were analysed as marks relative to the pass mark at the first attempt. Results PLAB1 marks were a valid predictor of MRCP(UK) Part 1, MRCP(UK) Part 2, and MRCGP AKT (r=0.521, 0.390, and 0.490; all P<0.001). PLAB2 marks correlated with MRCP(UK) PACES and MRCGP CSA (r=0.274, 0.321; both P<0.001). PLAB graduates had significantly lower MRCP(UK) and MRCGP assessments (Glass’s Δ=0.94, 0.91, 1.40, 1.01, and 1.82 for MRCP(UK) Part 1, Part 2, and PACES and MRCGP AKT and CSA), and were more likely to fail assessments

Maximal exercise and muscle oxygen extraction in acclimatizing lowlanders and high altitude natives

PubMed Central

Lundby, Carsten; Sander, Mikael; van Hall, Gerrit; Saltin, Bengt; Calbet, José A L

2006-01-01

The tight relation between arterial oxygen content and maximum oxygen uptake () within a given person at sea level is diminished with altitude acclimatization. An explanation often suggested for this mismatch is impairment of the muscle O2 extraction capacity with chronic hypoxia, and is the focus of the present study. We have studied six lowlanders during maximal exercise at sea level (SL) and with acute (AH) exposure to 4100 m altitude, and again after 2 (W2) and 8 weeks (W8) of altitude sojourn, where also eight high altitude native (Nat) Aymaras were studied. Fractional arterial muscle O2 extraction at maximal exercise was 90.0 ± 1.0% in the Danish lowlanders at sea level, and remained close to this value in all situations. In contrast to this, fractional arterial O2 extraction was 83.2 ± 2.8% in the high altitude natives, and did not change with the induction of normoxia. The capillary oxygen conductance of the lower extremity, a measure of oxygen diffusing capacity, was decreased in the Danish lowlanders after 8 weeks of acclimatization, but was still higher than the value obtained from the high altitude natives. The values were (in ml min−1 mmHg−1) 55.2 ± 3.7 (SL), 48.0 ± 1.7 (W2), 37.8 ± 0.4 (W8) and 27.7 ± 1.5 (Nat). However, when correcting oxygen conductance for the observed reduction in maximal leg blood flow with acclimatization the effect diminished. When calculating a hypothetical leg at altitude using either the leg blood flow or the O2 conductance values obtained at sea level, the former values were almost completely restored to sea level values. This would suggest that the major determinant for not to increase with acclimatization is the observed reduction in maximal leg blood flow and O2 conductance. PMID:16581864

Lowland sheep: the nutrition and management cycle.

PubMed

Speedy, A W; Clark, C F

1981-06-06

Good management of lowland sheep depends on strategic uses of resources during the management cycle and manipulation of body reserves. Critical periods are around mating, late pregnancy and early lactation. Good condition at mating is achieved by expanding the grazing area apportioned to the ewes in autumn. Thereafter, ewes are restricted to allow the resting of pasture for spring growth. A feeding plan for late pregnancy is given which takes account of body condition score and expected lambing date. The recommended concentrate ration contains a proportion of undegradable protein which is fed until grass growth can support lactation. Nutrition in later lactation is not limiting provided fertiliser nitrogen is applied regularly at a level related to stocking rate. By integration with other enterprises (cattle and crops), efficient use of resources is achieved.

Chance UK

ERIC Educational Resources Information Center

McGrath, Gracia

2003-01-01

Chance UK is a unique charity in the UK that specialises in mentoring programmes for primary schoolchildren with behavioural problems. It was founded in 1995 by a policeman, Chief Superintendent Paul Mathias, who believed that by stepping in early, young children with behavioural difficulties could be given the chance to develop the necessary…

Evaluating barriers to native seedling establishment in an invaded Hawaiian lowland wet forest

Treesearch

S. Cordell; R. Ostertag; B. Rowe; L. Sweinhart; L. Vasquez-Radonic; J. Michaud; T.C. Cole; J.R. Schulten

2009-01-01

Many tropical island forest ecosystems are dominated by non-native plant species and lack native species regeneration in the understorey. Comparison of replicated control and removal plots offers an opportunity to examine not only invasive species impacts but also the restoration potential of native species. In lowland Hawaiian wet forests little is known about native...

Thermokarst rates intensify due to climate change and forest fragmentation in an Alaskan boreal forest lowland.

PubMed

Lara, Mark J; Genet, Hélène; McGuire, Anthony D; Euskirchen, Eugénie S; Zhang, Yujin; Brown, Dana R N; Jorgenson, Mark T; Romanovsky, Vladimir; Breen, Amy; Bolton, William R

2016-02-01

Lowland boreal forest ecosystems in Alaska are dominated by wetlands comprised of a complex mosaic of fens, collapse-scar bogs, low shrub/scrub, and forests growing on elevated ice-rich permafrost soils. Thermokarst has affected the lowlands of the Tanana Flats in central Alaska for centuries, as thawing permafrost collapses forests that transition to wetlands. Located within the discontinuous permafrost zone, this region has significantly warmed over the past half-century, and much of these carbon-rich permafrost soils are now within ~0.5 °C of thawing. Increased permafrost thaw in lowland boreal forests in response to warming may have consequences for the climate system. This study evaluates the trajectories and potential drivers of 60 years of forest change in a landscape subjected to permafrost thaw in unburned dominant forest types (paper birch and black spruce) associated with location on elevated permafrost plateau and across multiple time periods (1949, 1978, 1986, 1998, and 2009) using historical and contemporary aerial and satellite images for change detection. We developed (i) a deterministic statistical model to evaluate the potential climatic controls on forest change using gradient boosting and regression tree analysis, and (ii) a 30 × 30 m land cover map of the Tanana Flats to estimate the potential landscape-level losses of forest area due to thermokarst from 1949 to 2009. Over the 60-year period, we observed a nonlinear loss of birch forests and a relatively continuous gain of spruce forest associated with thermokarst and forest succession, while gradient boosting/regression tree models identify precipitation and forest fragmentation as the primary factors controlling birch and spruce forest change, respectively. Between 1950 and 2009, landscape-level analysis estimates a transition of ~15 km² or ~7% of birch forests to wetlands, where the greatest change followed warm periods. This work highlights that the vulnerability and resilience of

Thermokarst rates intensify due to climate change and forest fragmentation in an Alaskan boreal forest lowland

USGS Publications Warehouse

Lara, M.; Genet, Helene; McGuire, A. David; Euskirchen, Eugénie S.; Zhang, Yujin; Brown, Dana R. N.; Jorgenson, M.T.; Romanovsky, V.; Breen, Amy L.; Bolton, W.R.

2016-01-01

Lowland boreal forest ecosystems in Alaska are dominated by wetlands comprised of a complex mosaic of fens, collapse-scar bogs, low shrub/scrub, and forests growing on elevated ice-rich permafrost soils. Thermokarst has affected the lowlands of the Tanana Flats in central Alaska for centuries, as thawing permafrost collapses forests that transition to wetlands. Located within the discontinuous permafrost zone, this region has significantly warmed over the past half-century, and much of these carbon-rich permafrost soils are now within ~0.5 °C of thawing. Increased permafrost thaw in lowland boreal forests in response to warming may have consequences for the climate system. This study evaluates the trajectories and potential drivers of 60 years of forest change in a landscape subjected to permafrost thaw in unburned dominant forest types (paper birch and black spruce) associated with location on elevated permafrost plateau and across multiple time periods (1949, 1978, 1986, 1998, and 2009) using historical and contemporary aerial and satellite images for change detection. We developed (i) a deterministic statistical model to evaluate the potential climatic controls on forest change using gradient boosting and regression tree analysis, and (ii) a 30 × 30 m land cover map of the Tanana Flats to estimate the potential landscape-level losses of forest area due to thermokarst from 1949 to 2009. Over the 60-year period, we observed a nonlinear loss of birch forests and a relatively continuous gain of spruce forest associated with thermokarst and forest succession, while gradient boosting/regression tree models identify precipitation and forest fragmentation as the primary factors controlling birch and spruce forest change, respectively. Between 1950 and 2009, landscape-level analysis estimates a transition of ~15 km² or ~7% of birch forests to wetlands, where the greatest change followed warm periods. This work highlights that the vulnerability and resilience of

Comparison of SPI and SPEI applicability for drought impact assessment on crop production in the Danubian Lowland and the East Slovakian Lowland

NASA Astrophysics Data System (ADS)

Labudová, L.; Labuda, M.; Takáč, J.

2017-04-01

Drought belongs among the main impact factors considering crop yields. Therefore, this paper is focused on the assessment of drought occurrence and intensity as well as on its impact on crop yields on the Danubian and the East Slovakian lowlands with the spatial resolution at district level. Yield data were the main limitation of the study, which resulted in the limited length of the assessed period (1996-2013). The standardized yields of ten crops (winter wheat, spring wheat, winter barley, spring barley, rye, maize, potatoes, oilseed rape, sunflower, and sugar beet) were correlated with monthly, 2-, and 3-monthly standardized precipitation index (SPI) and standardized precipitation and evapotranspiration index (SPEI). For this purpose, the common significance level of alpha = 0.05 was used. The temporal evolution of both indices and drought occurrence during the period 1961-2013 were assessed for each district. Most crops show a higher correlation with the SPEI than with the SPI in contrast to potatoes, which reached a higher significant correlation using the SPI. The correlation also increases with increasing number of months within a time step. The highest correlation can be seen between maize and the 3-monthly SPEI in August representing summer precipitation and potential evapotranspiration conditions. Furthermore, a very high correlation was recorded considering sugar beet, which is influenced mainly by summer precipitation, because the correlation coefficient between the sugar beet and the 3-monthly SPI is as high as using the 3-monthly SPEI. Crop yields in the East Slovakian Lowland do not seem to be influenced by wet/dry periods identified using the SPI and the SPEI as their correlation with both indices is quite low and insignificant.

Vegetation and floristics of a lowland tropical rainforest in northeast Australia

PubMed Central

Apgaua, Deborah M. G.; Campbell, Mason J; Cox, Casey J; Crayn, Darren M; Ishida, Françoise Y; Laidlaw, Melinda J; Liddell, Michael J; Seager, Michael; Laurance, Susan G. W.

2016-01-01

Abstract Background Full floristic data, tree demography, and biomass estimates incorporating non-tree lifeforms are seldom collected and reported for forest plots in the tropics. Established research stations serve as important repositories of such biodiversity and ecological data. With a canopy crane setup within a tropical lowland rainforest estate, the 42-ha Daintree Rainforest Observatory (DRO) in Cape Tribulation, northern Australia is a research facility of international significance. We obtained an estimate of the vascular plant species richness for the site, by surveying all vascular plant species from various mature-phase, remnant and open vegetation patches within the site. We also integrate and report the demography and basal areas of trees ≥ 10 cm diameter at breast height (dbh) in a new 1-ha core plot, an extension to the pre-existing forest 1-ha plot under the canopy crane. In addition, we report for the canopy crane plot new demography and basal areas for smaller-size shrubs and treelets subsampled from nine 20 m2 quadrats, and liana basal area and abundance from the whole plot. The DRO site has an estimated total vascular plant species richness of 441 species, of which 172 species (39%) are endemic to Australia, and 4 species are endemics to the Daintree region. The 2 x 1-ha plots contains a total of 262 vascular plant species of which 116 (1531 individuals) are tree species ≥ 10 cm dbh. We estimate a stem basal area of 34.9 m2 ha-1, of which small stems (tree saplings and shrubs <10cm dbh) and lianas collectively contribute c.4.2%. Comparing the stem density-diversity patterns of the DRO forest with other tropical rainforests globally, our meta-analysis shows that DRO forests has a comparatively high stem density and moderate species diversity, due to the influence of cyclones. These data will provide an important foundation for ecological and conservation studies in lowland tropical forest. New information We present a floristic checklist, a

Plant responses to fertilization experiments in lowland, species-rich, tropical forests.

PubMed

Wright, S Joseph; Turner, Benjamin L; Yavitt, Joseph B; Harms, Kyle E; Kaspari, Michael; Tanner, Edmund V J; Bujan, Jelena; Griffin, Eric A; Mayor, Jordan R; Pasquini, Sarah C; Sheldrake, Merlin; Garcia, Milton N

2018-05-01

We present a meta-analysis of plant responses to fertilization experiments conducted in lowland, species-rich, tropical forests. We also update a key result and present the first species-level analyses of tree growth rates for a 15-yr factorial nitrogen (N), phosphorus (P), and potassium (K) experiment conducted in central Panama. The update concerns community-level tree growth rates, which responded significantly to the addition of N and K together after 10 yr of fertilization but not after 15 yr. Our experimental soils are infertile for the region, and species whose regional distributions are strongly associated with low soil P availability dominate the local tree flora. Under these circumstances, we expect muted responses to fertilization, and we predicted species associated with low-P soils would respond most slowly. The data did not support this prediction, species-level tree growth responses to P addition were unrelated to species-level soil P associations. The meta-analysis demonstrated that nutrient limitation is widespread in lowland tropical forests and evaluated two directional hypotheses concerning plant responses to N addition and to P addition. The meta-analysis supported the hypothesis that tree (or biomass) growth rate responses to fertilization are weaker in old growth forests and stronger in secondary forests, where rapid biomass accumulation provides a nutrient sink. The meta-analysis found no support for the long-standing hypothesis that plant responses are stronger for P addition and weaker for N addition. We do not advocate discarding the latter hypothesis. There are only 14 fertilization experiments from lowland, species-rich, tropical forests, 13 of the 14 experiments added nutrients for five or fewer years, and responses vary widely among experiments. Potential fertilization responses should be muted when the species present are well adapted to nutrient-poor soils, as is the case in our experiment, and when pest pressure increases with

Phylogeography of Declining Relict and Lowland Leopard Frogs in the Desert Southwest of North America

EPA Science Inventory

We investigated the phylogeography of the closely related relict leopard frog (Rana onca) and lowland leopard frog (R. yavapaiensis) – two declining anurans from the warm-desert regions of southwestern North America. We used sequence data from two mitochondrial DNA genes to asses...

Landscape changes as a factor affecting the course and consequences of extreme floods in the Otava river basin, Czech Republic.

PubMed

Langhammer, Jakub; Vilímek, Vít

2008-09-01

The paper presents the analysis of anthropogenical modifications of the landscape in relation to the course and consequences of floods. The research was conducted in the Otava river basin which represents the core zone of the extreme flood in August 2002 in Central Europe. The analysis was focused on the key indicators of landscape modification potentially affecting the runoff process - the long-term changes of land-use, changes of land cover structure, land drainage, historical shortening of the river network and the modifications of streams and floodplains. The information on intensity and spatial distribution of modifications was derived from different data sources--historical maps, available GIS data, remote sensing and field mapping. The results revealed a high level of spatial diversity of anthropogenical modifications in different parts of the river basin. The intensive modifications in most of indicators were concentrated in the lowland region of the river basin due to its agricultural use; however important changes were also recorded in the headwater region of the basin. The high spatial diversity of the modifications may result in their varying effect on the course and consequences of floods in different parts of the river basin. This effect is demonstrated by the cluster analysis based on the matrix of indicators of stream and floodplain modification, physiogeographical characteristics and geomorphological evidences of the flood in August 2002, derived from the individual thematic layers using GIS.

An ecological economic assessment of flow regimes in a hydropower dominated river basin: the case of the lower Zambezi River, Mozambique.

PubMed

Fanaian, Safa; Graas, Susan; Jiang, Yong; van der Zaag, Pieter

2015-02-01

The flow regime of rivers, being an integral part of aquatic ecosystems, provides many important services benefiting humans in catchments. Past water resource developments characterized by river embankments and dams, however, were often dominated by one (or few) economic use(s) of water. This results in a dramatically changed flow regime negatively affecting the provision of other ecosystem services sustained by the river flow. This study is intended to demonstrate the value of alternative flow regimes in a river that is highly modified by the presence of large hydropower dams and reservoirs, explicitly accounting for a broad range of flow-dependent ecosystem services. In this study, we propose a holistic approach for conducting an ecological economic assessment of a river's flow regime. This integrates recent advances in the conceptualization and classification of ecosystem services (UK NEA, 2011) with the flow regime evaluation technique developed by Korsgaard (2006). This integrated approach allows for a systematic comparison of the economic values of alternative flow regimes, including those that are considered beneficial for aquatic ecosystems. As an illustration, we applied this combined approach to the Lower Zambezi Basin, Mozambique. Empirical analysis shows that even though re-operating dams to create environmentally friendly flow regimes reduces hydropower benefits, the gains to goods derived from the aquatic ecosystem may offset the forgone hydropower benefits, thereby increasing the total economic value of river flow to society. The proposed integrated flow assessment approach can be a useful tool for welfare-improving decision-making in managing river basins. Copyright © 2014 Elsevier B.V. All rights reserved.

UK-trained junior doctors' intentions to work in UK medicine: questionnaire surveys, three years after graduation

PubMed Central

Surman, Geraldine; Goldacre, Michael J

2017-01-01

Objective To report on the career intentions, three years after qualification, of 12 national cohorts of UK-trained doctors who qualified between 1974 and 2012, and, specifically, to compare recent UK medical graduates’ intentions to work in medicine in the UK with earlier graduates. Design Questionnaire surveys of cohorts of UK medical graduates defined by year of graduation. Setting UK. Participants 30,272 UK medical graduates. Main outcome measures Stated level of intention to pursue a long-term career in medicine in the UK. Results The response rate was 62% (30,272/48,927). We examined responses to the question ‘Apart from temporary visits abroad, do you intend to practise medicine in the United Kingdom for the foreseeable future?' Of doctors from UK homes, 90% had specified that they would ‘definitely or probably’ practise medicine in the UK in the surveys of 1977–1986, 81% in 1996–2011 and 64% in 2015. Those who said that they would probably or definitely not practise medicine in the UK comprised 5% in 1977–1986, 8% in 1996–2011 and 15% in 2015. Most who were not definite about a future career in UK medicine indicated that they would wish to practise medicine outside the UK rather than to leave medicine. Conclusions The wish to remain in UK medical practice in the 2015 survey was unprecedentedly low in this unique series of 40 years of surveys. PMID:29116902

UK-trained junior doctors' intentions to work in UK medicine: questionnaire surveys, three years after graduation.

PubMed

Surman, Geraldine; Goldacre, Michael J; Lambert, Trevor W

2017-12-01

Objective To report on the career intentions, three years after qualification, of 12 national cohorts of UK-trained doctors who qualified between 1974 and 2012, and, specifically, to compare recent UK medical graduates' intentions to work in medicine in the UK with earlier graduates. Design Questionnaire surveys of cohorts of UK medical graduates defined by year of graduation. Setting UK. Participants 30,272 UK medical graduates. Main outcome measures Stated level of intention to pursue a long-term career in medicine in the UK. Results The response rate was 62% (30,272/48,927). We examined responses to the question ' Apart from temporary visits abroad, do you intend to practise medicine in the United Kingdom for the foreseeable future?' Of doctors from UK homes, 90% had specified that they would 'definitely or probably' practise medicine in the UK in the surveys of 1977-1986, 81% in 1996-2011 and 64% in 2015. Those who said that they would probably or definitely not practise medicine in the UK comprised 5% in 1977-1986, 8% in 1996-2011 and 15% in 2015. Most who were not definite about a future career in UK medicine indicated that they would wish to practise medicine outside the UK rather than to leave medicine. Conclusions The wish to remain in UK medical practice in the 2015 survey was unprecedentedly low in this unique series of 40 years of surveys.

Adaptive Epigenetic Differentiation between Upland and Lowland Rice Ecotypes Revealed by Methylation-Sensitive Amplified Polymorphism.

PubMed

Xia, Hui; Huang, Weixia; Xiong, Jie; Tao, Tao; Zheng, Xiaoguo; Wei, Haibin; Yue, Yunxia; Chen, Liang; Luo, Lijun

2016-01-01

The stress-induced epimutations could be inherited over generations and play important roles in plant adaption to stressful environments. Upland rice has been domesticated in water-limited environments for thousands of years and accumulated drought-induced epimutations of DNA methylation, making it epigenetically differentiated from lowland rice. To study the epigenetic differentiation between upland and lowland rice ecotypes on their drought-resistances, the epigenetic variation was investigated in 180 rice landraces under both normal and osmotic conditions via methylation-sensitive amplified polymorphism (MSAP) technique. Great alterations (52.9~54.3% of total individual-locus combinations) of DNA methylation are recorded when rice encountering the osmotic stress. Although the general level of epigenetic differentiation was very low, considerable level of ΦST (0.134~0.187) was detected on the highly divergent epiloci (HDE). The HDE detected in normal condition tended to stay at low levels in upland rice, particularly the ones de-methylated in responses to osmotic stress. Three out of four selected HDE genes differentially expressed between upland and lowland rice under normal or stressed conditions. Moreover, once a gene at HDE was up-/down-regulated in responses to the osmotic stress, its expression under the normal condition was higher/lower in upland rice. This result suggested expressions of genes at the HDE in upland rice might be more adaptive to the osmotic stress. The epigenetic divergence and its influence on the gene expression should contribute to the higher drought-resistance in upland rice as it is domesticated in the water-limited environment.

Adaptive Epigenetic Differentiation between Upland and Lowland Rice Ecotypes Revealed by Methylation-Sensitive Amplified Polymorphism

PubMed Central

Xiong, Jie; Tao, Tao; Zheng, Xiaoguo; Wei, Haibin; Yue, Yunxia; Chen, Liang; Luo, Lijun

2016-01-01

The stress-induced epimutations could be inherited over generations and play important roles in plant adaption to stressful environments. Upland rice has been domesticated in water-limited environments for thousands of years and accumulated drought-induced epimutations of DNA methylation, making it epigenetically differentiated from lowland rice. To study the epigenetic differentiation between upland and lowland rice ecotypes on their drought-resistances, the epigenetic variation was investigated in 180 rice landraces under both normal and osmotic conditions via methylation-sensitive amplified polymorphism (MSAP) technique. Great alterations (52.9~54.3% of total individual-locus combinations) of DNA methylation are recorded when rice encountering the osmotic stress. Although the general level of epigenetic differentiation was very low, considerable level of ΦST (0.134~0.187) was detected on the highly divergent epiloci (HDE). The HDE detected in normal condition tended to stay at low levels in upland rice, particularly the ones de-methylated in responses to osmotic stress. Three out of four selected HDE genes differentially expressed between upland and lowland rice under normal or stressed conditions. Moreover, once a gene at HDE was up-/down-regulated in responses to the osmotic stress, its expression under the normal condition was higher/lower in upland rice. This result suggested expressions of genes at the HDE in upland rice might be more adaptive to the osmotic stress. The epigenetic divergence and its influence on the gene expression should contribute to the higher drought-resistance in upland rice as it is domesticated in the water-limited environment. PMID:27380174

Sources, distribution and export coefficient of phosphorus in lowland polders of Lake Taihu Basin, China.

PubMed

Huang, Jiacong; Gao, Junfeng; Jiang, Yong; Yin, Hongbin; Amiri, Bahman Jabbarian

2017-12-01

Identifying phosphorus (P) sources, distribution and export from lowland polders is important for P pollution management, however, is challenging due to the high complexity of hydrological and P transport processes in lowland areas. In this study, the spatial pattern and temporal dynamics of P export coefficient (PEC) from all the 2539 polders in Lake Taihu Basin, China were estimated using a coupled P model for describing P dynamics in a polder system. The estimated amount of P export from polders in Lake Taihu Basin during 2013 was 1916.2 t/yr, with a spatially-averaged PEC of 1.8 kg/ha/yr. PEC had peak values (more than 4.0 kg/ha/yr) in the polders near/within the large cities, and was high during the rice-cropping season. Sensitivity analysis based on the coupled P model revealed that the sensitive factors controlling the PEC varied spatially and changed through time. Precipitation and air temperature were the most sensitive factors controlling PEC. Culvert controlling and fertilization were sensitive factors controlling PEC during some periods. This study demonstrated an estimation of PEC from 2539 polders in Lake Taihu Basin, and an identification of sensitive environmental factors affecting PEC. The investigation of polder P export in a watershed scale is helpful for water managers to learn the distribution of P sources, to identify key P sources, and thus to achieve best management practice in controlling P export from lowland areas. Copyright © 2017 Elsevier Ltd. All rights reserved.

Invertebrate and fish assemblage relations to dissolved Oxygen minima in lowland streams of southwestern Louisiana

USGS Publications Warehouse

Justus, B.G.; Mize, Scott V.; Kroes, Daniel; Wallace, James E.

2012-01-01

Dissolved oxygen (DO) concentrations in lowland streams are naturally lower than those in upland streams; however, in some regions where monitoring data are lacking, DO criteria originally established for upland streams have been applied to lowland streams. This study investigated the DO concentrations at which fish and invertebrate assemblages at 35 sites located on lowland streams in southwestern Louisiana began to demonstrate biological thresholds.Average threshold values for taxa richness, diversity and abundance metrics were 2.6 and 2.3 mg/L for the invertebrate and fish assemblages, respectively. These thresholds are approximately twice the DO concentration that some native fish species are capable of tolerating and are comparable with DO criteria that have been recently applied to some coastal streams in Louisiana and Texas. DO minima >2.5 mg/L were favoured for all but extremely tolerant taxa. Extremely tolerant taxa had respiratory adaptations that gave them a competitive advantage, and their success when DO minima were <2 mg/L could be related more to reductions in competition or predation than to DO concentration directly.DO generally had an inverse relation to the amount of agriculture in the buffer area; however, DO concentrations at sites with both low and high amounts of agriculture (including three least-disturbed sites) declined to <2.5 mg/L. Thus, although DO fell below a concentration that was identified as an approximate biological threshold, sources of this condition were sometimes natural (allochthonous material) and had little relation to anthropogenic activity.

The environmental state of rivers in the Balkans--a review within the DPSIR framework.

PubMed

Skoulikidis, Nikolaos Th

2009-04-01

Fifteen major Balkan rivers with over 80% of the inflows in Eastern Mediterranean were examined for their environmental state within the DPSIR framework. Physicogeographic and hydrochemical conditions differ substantially among river basins, which may be roughly classified into three main zones. Despite strong fragmentation, most of the rivers are liable to flash floods and have low summer flow. Decreasing precipitation and (mis)management caused a dramatic discharge reduction over the last decades. Wars, political instability, economical crises over the past decades, combined with administrative and structural constraints, poor environmental planning and inspection and, frequently, a lack of environmental awareness imposed significant pressures on rivers. Large wetland areas were drained in favour of widespread intensive agriculture. The treatment of municipal wastewaters is barely adequate in Greece and insufficient elsewhere, while management and treatment of mining and industrial wastewaters is overall poor. In general, lowland river sections are hydro-morphologically modified and are at the greatest pollution risk, while upstream areas mostly retain their natural conditions. Nutrient concentrations in a number of central and eastern Balkan rivers often exceed quality standards, whereas pesticides and heavy metals, partly of geochemical origin, occasionally exceed quality standards. Reservoirs retain vast masses of sediments, thus adversely affecting delta evolution, while dam operation disturbs the seasonal hydrological and hydrochemical regimes. Almost all Balkan countries face daunting water resource challenges because of urgently needed investments in water supply, sanitation, irrigation, and hydroelectricity. International treaties and designations and European Union Directives have mobilized pollution mitigation and conservation efforts. However, the application of environmental legislation has proved in a number of cases inadequate. Constraints arise

Enhancing the Biodiversity of Ditches in Intensively Managed UK Farmland

PubMed Central

Shaw, Rosalind F.; Johnson, Paul J.; Macdonald, David W.; Feber, Ruth E.

2015-01-01

Drainage ditches, either seasonally flooded or permanent, are commonly found on intensively managed lowland farmland in the UK. They are potentially important for wetland biodiversity but, despite their ubiquity, information on their biodiversity and management in the wider countryside is scarce. We surveyed 175 ditches for their physical and chemical characteristics, spatial connectivity, plant communities and aquatic invertebrates in an area of intensively managed farmland in Oxfordshire, UK and collected information on ditch management from farmer interviews. Water depth and shade had a small impact on the diversity of plant and invertebrate communities in ditches. Increased shade over the ditch channel resulted in reduced taxonomic richness of both channel vegetation and aquatic invertebrates and channel vegetation cover was lower at shaded sites. Invertebrate taxonomic richness was higher when water was deeper. Spatial connectivity had no detectable impact on the aquatic invertebrate or plant communities found in ditches. The number of families within the orders Ephemeroptera, Plecoptera and Trichoptera (EPT), which contain many pollution-sensitive species, declined with decreasing pH of ditch water. As time since dredging increased, the number of EPT families increased in permanent ditches but decreased in temporary ditches. Whether or not a ditch was in an agri-environment scheme had little impact on the reported management regime or biodiversity value of the ditch. Measures for increasing the amount of water in ditches, by increasing the water depth or promoting retention of water in ditches, could increase the biodiversity value of ditches in agricultural land. Some temporary ditches for specialised species should be retained. Reducing the amount of shade over narrow ditches by managing adjacent hedgerows is also likely to increase the species diversity of plant and invertebrate communities within the ditch. We recommend that to preserve or enhance the

Enhancing the Biodiversity of Ditches in Intensively Managed UK Farmland.

PubMed

Shaw, Rosalind F; Johnson, Paul J; Macdonald, David W; Feber, Ruth E

2015-01-01

Drainage ditches, either seasonally flooded or permanent, are commonly found on intensively managed lowland farmland in the UK. They are potentially important for wetland biodiversity but, despite their ubiquity, information on their biodiversity and management in the wider countryside is scarce. We surveyed 175 ditches for their physical and chemical characteristics, spatial connectivity, plant communities and aquatic invertebrates in an area of intensively managed farmland in Oxfordshire, UK and collected information on ditch management from farmer interviews. Water depth and shade had a small impact on the diversity of plant and invertebrate communities in ditches. Increased shade over the ditch channel resulted in reduced taxonomic richness of both channel vegetation and aquatic invertebrates and channel vegetation cover was lower at shaded sites. Invertebrate taxonomic richness was higher when water was deeper. Spatial connectivity had no detectable impact on the aquatic invertebrate or plant communities found in ditches. The number of families within the orders Ephemeroptera, Plecoptera and Trichoptera (EPT), which contain many pollution-sensitive species, declined with decreasing pH of ditch water. As time since dredging increased, the number of EPT families increased in permanent ditches but decreased in temporary ditches. Whether or not a ditch was in an agri-environment scheme had little impact on the reported management regime or biodiversity value of the ditch. Measures for increasing the amount of water in ditches, by increasing the water depth or promoting retention of water in ditches, could increase the biodiversity value of ditches in agricultural land. Some temporary ditches for specialised species should be retained. Reducing the amount of shade over narrow ditches by managing adjacent hedgerows is also likely to increase the species diversity of plant and invertebrate communities within the ditch. We recommend that to preserve or enhance the

Survey of radiation intensities at the rivers Lafnitz and Pinka using hemispherical images and analysis of the shading effect of the riparian vegetation.

NASA Astrophysics Data System (ADS)

Holzapfel, Gerda; Hlousek, Christoph; Rauch, Hans Peter; Bartel, Wolfgang

2014-05-01

Climate change scenarios predict an increase of temperature about 2 to 2.5°C until 2040 for Austrian lowlands. Especially the pannonian area in eastern Austria, with hot and dry summers and high temperatures is affected by these forecasts. These changes in global climate will also lead to negative consequences for freshwater ecosystems by an increase in water temperature. If there is sufficient natural bank vegetation in riparian areas, the increasing resilience of those freshwater ecosystems will be supported, whereas negative impacts such as the rise of river water temperature will be balanced. This study shows the degree of riparian vegetation as a shading element at the two investigated rivers Lafnitz and Pinka, located in eastern Austria. In field surveys hemispherical photographs were gathered on 95 points in the middle as well as the banks of both rivers. Subsequent surrounding riparian vegetation and terrain was surveyed by means of vegetation composition, height, density and vegetation overhang into the river as well as river size and bank inclination. Hemispherical Photographs were processed by the software Hemiview 2.1 and provide resulting global site factors, which inform about radiation reduction caused by riparian vegetation. With the global site factors, vegetation and river morphology data of the 95 selected sites the shading potential of predominant riparian vegetation types was investigated. Results show the most impacting parameters on solar radiation passage through riparian vegetation.

Quantifying urban river-aquifer fluid exchange processes: a multi-scale problem.

PubMed

Ellis, Paul A; Mackay, Rae; Rivett, Michael O

2007-04-01

Groundwater-river exchanges in an urban setting have been investigated through long term field monitoring and detailed modelling of a 7 km reach of the Tame river as it traverses the unconfined Triassic Sandstone aquifer that lies beneath the City of Birmingham, UK. Field investigations and numerical modelling have been completed at a range of spatial and temporal scales from the metre to the kilometre scale and from event (hourly) to multi-annual time scales. The objective has been to quantify the spatial and temporal flow distributions governing mixing processes at the aquifer-river interface that can affect the chemical activity in the hyporheic zone of this urbanised river. The hyporheic zone is defined to be the zone of physical mixing of river and aquifer water. The results highlight the multi-scale controls that govern the fluid exchange distributions that influence the thickness of the mixing zone between urban rivers and groundwater and the patterns of groundwater flow through the bed of the river. The morphologies of the urban river bed and the adjacent river bank sediments are found to be particularly influential in developing the mixing zone at the interface between river and groundwater. Pressure transients in the river are also found to exert an influence on velocity distribution in the bed material. Areas of significant mixing do not appear to be related to the areas of greatest groundwater discharge and therefore this relationship requires further investigation to quantify the actual remedial capacity of the physical hyporheic zone.

Adaptive Management of Return Flows: Lessons from a Case Study in Environmental Water Delivery to a Floodplain River

NASA Astrophysics Data System (ADS)

Wolfenden, Benjamin J.; Wassens, Skye M.; Jenkins, Kim M.; Baldwin, Darren S.; Kobayashi, Tsuyoshi; Maguire, James

2018-03-01

For many floodplain rivers, reinstating wetland connectivity is necessary for ecosystems to recover from decades of regulation. Environmental return flows (the managed delivery of wetland water to an adjacent river) can be used strategically to facilitate natural ecosystem connectivity, enabling the transfer of nutrients, energy, and biota from wetland habitats to the river. Using an informal adaptive management framework, we delivered return flows from a forested wetland complex into a large lowland river in south-eastern Australia. We hypothesized that return flows would (a) increase river nutrient concentrations; (b) reduce wetland nutrient concentrations; (c) increase rates of ecosystem metabolism through the addition of potentially limiting nutrients, causing related increases in the concentration of water column chlorophyll-a; and (d) increase the density and species richness of microinvertebrates in riverine benthic habitats. Our monitoring results demonstrated a small increase in the concentrations of several key nutrients but no evidence for significant ecological responses was found. Although return flows can be delivered from forested floodplain areas without risking hypoxic blackwater events, returning nutrient and carbon-rich water to increase riverine productivity is limited by the achievable scale of return flows. Nevertheless, using return flows to flush carbon from floodplains may be a useful management tool to reduce carbon loads, preparing floodplains for subsequent releases (e.g., mitigating the risk of hypoxic blackwater events). In this example, adaptive management benefited from a semi-formal collaboration between science and management that allowed for prompt decision-making.

Promoting SETI in the UK

NASA Astrophysics Data System (ADS)

Penny, Alan

2013-10-01

MEETING REPORT What does the UK presently do in the search for extraterrestrial intelligence and what are the plans for the future? Alan Penny reports on a meeting of UK academics active in SETI, held as sessions in the recent National Astronomy Meeting in Scotland - and the formation of the UK SETI Research Network to promote UK academic work.

Seasonal rainfall-runoff relationships in a lowland forested watershed in the southeastern USA

Treesearch

Ileana La Torre Torres; Devendra Amatya; Ge Sun; Timothy Callahan

2011-01-01

Hydrological processes of lowland watersheds of the southern USA are not well understood compared to a hilly landscape due to their unique topography, soil compositions, and climate. This study describes the seasonal relationships between rainfall patterns and runoff (sum of storm flow and base flow) using 13 years (1964–1976) of rainfall and stream flow data for a low...

Assessing the continuity of the upland sediment cascade, fluvial geomorphic response of an upland river to an extreme flood event: Storm Desmond, Cumbria, UK.

NASA Astrophysics Data System (ADS)

Joyce, Hannah; Hardy, Richard; Warburton, Jeff

2017-04-01

Hillslope erosion and accelerated lake sedimentation are often viewed as the source and main storage elements in the upland sediment cascade. However, the continuity of sediment transfer through intervening valley systems has rarely been evaluated during extreme events. Storm Desmond (4th - 6th December, 2015) produced record-breaking rainfall maximums in the UK: 341.4 mm rainfall was recorded in a 24 hour period at Honister Pass, Western Lake District, and 405 mm of rainfall was recorded in a 38 hour period at Thirlmere, central Lake District. The storm was the largest in a 150 year local rainfall series, and exceeded previous new records set in the 2005 and 2009 floods. During this exceptional event, rivers over topped flood defences, and caused damage to over 257 bridges, flooded over 5000 homes and businesses, and caused substantial geomorphic change along upland rivers. This research quantifies the geomorphic and sedimentary response to Storm Desmond along a regulated gravel-bed river: St John's Beck. St John's Beck (length 7.8 km) is a channelised low gradient river (0.005) downstream of Thirlmere Reservoir, which joins the River Greta, and flows through Keswick, where major flooding has occurred, before discharging into Bassenthwaite Lake. St John's Beck has a history of chronic sediment aggradation, erosion and reports of historic flooding date back to 1750. During Storm Desmond, riverbanks were eroded, coarse sediment was deposited across valuable farmland and access routes were destroyed, including a bridge and footpaths, disrupting local business. A sediment budget framework has been used to quantify geomorphic change and sedimentary characteristics of the event along St John's Beck. The volume and sediment size distribution of flood deposits, channel bars, tributary deposits, floodplain scour, riverbank erosion and in-channel bars were measured directly in the field and converted to mass using local estimates of coarse and fine sediment bulk densities

21st Century Projections of High Streamflow Events in the UK and Germany

NASA Astrophysics Data System (ADS)

Cioffi, Francesco; Rosario Conticello, Federico; Lall, Upmanu; Merz, Bruno

2017-04-01

Radiative effects of anthropogenic changes in atmospheric composition are expected to enhance the hydrological cycle leading to more frequent and intense floods. To explore if there will be an increased risk of river flooding in the future, 21st century projections under global warming scenarios of High Streamflow Events (HSEs) for UK and German rivers are carried out, using a model that statistically relates large-scale atmospheric predictors - 850 hPa Geopotential Height (GPH850) and Integrated Water Vapor Transport (IVT) - to the occurrence of HSEs in one or simultaneously in several streamflow gauges. Here, HSE is defined as the streamflow exceeding the 99th percentile of daily flowrate time series measured at streamflow gauges. For the common period 1960-2012, historical data from 57 streamflow gauges in UK and 61 streamflow gauges in Germany, as well as, reanalysis data of GPH850 and IVT fields, bounded from 90W to 70E and from 20N to 80N are used. The link between GPH850 configurations and HSEs, and more precisely, identification of the GPH850 states potentially able to generate HSEs, is performed by a combined Kohonen Networks (Self Organized Map, SOM) and Event Syncronization approach. Complex network and modularity methods are used to cluster streamflow gauges that share common GPH850 configurations. Then a model based on a conditional Poisson distribution, in which the parameter of the Poisson distribution is assumed to be a nonlinear function of GPH850 and IVT, allows for the identification of GPH850 state and threshold of IVT beyond which there is the HSE highest probability. Using that model, projections of 21st century changes in frequency of HSEs occurrence in UK and Germany are estimated using the simulated fields of GPH850 and IVT from selected GCMs belonging to the Coupled Model Inter-comparison Project Phase 5 (CMIP5). Among the different GCMs, those are selected whose retrospective predictor fields have consistent statistics with the

Senile plaques in an aged western lowland gorilla.

PubMed

Kimura, N; Nakamura, S; Goto, N; Narushima, E; Hara, I; Shichiri, S; Saitou, K; Nose, M; Hayashi, T; Kawamura, S; Yoshikawa, Y

2001-01-01

Senile plaques (SPs) were found in the cerebral cortex of a 44-year-old Western lowland gorilla (Gorilla gorilla gorilla). All the SPs were obtained as dense assemblies consisting of fibrous materials by silver impregnation, but were not detected by Congo red. More SPs were detected by immunostaining for amyloid beta protein (A beta) and a half of A beta-positive-SPs were also immunoreactive for apolipoprotein E. Moreover, all SPs were immunoreactive for A beta 42 and A beta 43, but not for A beta 40. SPs also did not contain A beta precursor protein-positive structures. These findings suggested that SPs in this case were diffuse plaques. To our knowledge, this is the first report of SPs in the gorilla.

Linking Watershed Nitrogen Sources with Nitrogen Dynamics in Rivers of Western Oregon, USA

NASA Astrophysics Data System (ADS)

Sobota, D. J.; Compton, J.; Goodwin, K. E.

2012-12-01

We constructed contemporary nitrogen (N) budgets for 25 river basins in the Willamette River Basin (WRB) of western Oregon, USA, to improve the understanding of how recent trends in human-driven N loading have influenced riverine N dynamics in the region. Nearly 20% of WRB stream length is currently in fair or poor condition because of high N concentrations. Additionally, nitrate contamination of drinking water affects at least 8,000 people in the WRB. We hypothesized that 1) the majority of N inputs in the WRB would originate from agricultural activities in lowland portions of watersheds, 2) annual riverine N yield (kg/ha/yr) would correspond to annual per area watershed N inputs, and 3) riverine N yields would be seasonal and highest during winter due to the region's Mediterranean climate. We calculated average annual N inputs for each study basin by summing newly available datasets describing spatially explicit N inputs of synthetic fertilizer, atmospheric deposition, crop biological N2 fixation, biological N2 fixation by red alder (Alnus rubra Bong.), livestock manure, and point sources for the period 1996 - 2007. Annual and seasonal riverine N exports were estimated with the USGS model LOADEST calibrated to N concentration data collected during the study period. We estimated that two-thirds of total N input to the WRB study basins in the 2000s came from synthetic fertilizer application. Nearly all fertilizer application occurred on the lowlands near watershed mouths. We found a wide range of riverine N yields from the study basins, ranging from one to 70 kg N/ha/yr. Across the study basins, N export was more strongly correlated to fertilizer application rates than to percent of agricultural area in the watershed. Low watershed N yields reflected a high proportion of watershed area in the forested Cascade Mountain Range, which received low N inputs mainly from atmospheric deposition. N yields from study basins were strongly seasonal, with at least 50%, and

60,000 years of vegetation and climate change in eastern, lowland Bolivia

NASA Astrophysics Data System (ADS)

Whitney, B. S.; Mayle, F. E.

2006-12-01

Presented here is a late Quaternary pollen record from Laguna La Gaiba (17°45`S, 57°35`W), a 55 km2 lake located at the western margin of the Pantanal basin, the world's largest tropical wetland, and the eastern limit of the Bolivian Chiquitano dry forest. A suite of 12 AMS radiocarbon dates on terrestrial macrofossils demonstrates a continuous sediment record spanning at least the last 60,000 years. Today, upland areas of the lake catchment are blanketed by closed-canopy semi-deciduous forest. However, arboreal pollen was largely absent from glacial-age sediments, indicative of a climate drier than present, and a landscape dominated by open, herbaceous savanna. Tropical forest appeared during the glacial-Holocene transition, pointing to increased precipitation, but was floristically different from those of the Holocene. Seasonally-dry tropical forest, floristically similar to that of today, appeared during the early Holocene. Changes in proportions of key dry forest taxa point to rising precipitation in the mid-late Holocene, consistent with other records from the southern hemisphere lowlands, as well as the tropical Andes. However, our evidence for reduced precipitation in the lowlands during the Last Glacial Maximum contrasts with high water- levels at Lake Titicaca and other sites on the Altiplano.

UK Environmental Prediction - integration and evaluation at the convective scale

NASA Astrophysics Data System (ADS)

Fallmann, Joachim; Lewis, Huw; Castillo, Juan Manuel; Pearson, David; Harris, Chris; Saulter, Andy; Bricheno, Lucy; Blyth, Eleanor

2016-04-01

It has long been understood that accurate prediction and warning of the impacts of severe weather requires an integrated approach to forecasting. For example, high impact weather is typically manifested through various interactions and feedbacks between different components of the Earth System. Damaging high winds can lead to significant damage from the large waves and storm surge along coastlines. The impact of intense rainfall can be translated through saturated soils and land surface processes, high river flows and flooding inland. The substantial impacts on individuals, businesses and infrastructure of such events indicate a pressing need to understand better the value that might be delivered through more integrated environmental prediction. To address this need, the Met Office, NERC Centre for Ecology & Hydrology and NERC National Oceanography Centre have begun to develop the foundations of a coupled high resolution probabilistic forecast system for the UK at km-scale. This links together existing model components of the atmosphere, coastal ocean, land surface and hydrology. Our initial focus has been on a 2-year Prototype project to demonstrate the UK coupled prediction concept in research mode. This presentation will provide an update on UK environmental prediction activities. We will present the results from the initial implementation of an atmosphere-land-ocean coupled system and discuss progress and initial results from further development to integrate wave interactions. We will discuss future directions and opportunities for collaboration in environmental prediction, and the challenges to realise the potential of integrated regional coupled forecasting for improving predictions and applications.

Combination of geochemical and hydrobiological tracers for the analysis of runoff generating processes in a lowland catchment

NASA Astrophysics Data System (ADS)

Faber, Claas; Wu, Naicheng; Ulrich, Uta; Fohrer, Nicola

2015-04-01

Since lowlands are characterised by flat topography and low hydraulic gradients, groundwater inflow has a large influence to streamflow generation in such catchments. In catchments with intense agricultural land use, artificial drainages are often another major contributor to streamflow. They shorten the soil passage and thus change the matter retention potential as well as runoff dynamics of a catchment. Contribution of surface runoff to streamflow is usually less important in volume. However, due to high concentrations of agrochemicals, surface runoff can constitute an important entry pathway into water bodies, especially if strong precipitation events coincide with fertilizer or pesticide application. The DFG funded project "Separating surface runoff from tile drainage flow in agricultural lowland catchments based on diatoms to improve modelled runoff components and phosphorous transport" investigates prevalent processes in this context in a 50 km² lowland catchment (Kielstau, Schleswig-Holstein, Germany) with the goal of improving existing models. End Member Mixing Analysis (EMMA) is used in the project to determine the relative importance of groundwater, tile drainage and surface runoff to streamflow at daily time steps. It became apparent that geochemical tracers are suitable for distinguishing surface runoff, but are weak for the separation of tile drainage and groundwater influence. We attribute this to the strong and complex interaction between soil water and shallow groundwater tables in the catchment. Recent studies (e.g. Pfister et al. 2011, Tauro et al. 2013) show the potential of diatoms as indicators for hydrological processes. Since we found diatoms to be suitable for the separation of tile drainage and stream samples (Wu et al., unpublished data) in our catchment, we are able to include diatom derived indices (e.g. density, species moisture indices, diversity indices) as traces in EMMA. Our results show that the inclusion of diatom data in the

River Mixing in the Amazon as a Driver of Concentration-Discharge Relationships

NASA Astrophysics Data System (ADS)

Bouchez, Julien; Moquet, Jean-Sébastien; Espinoza, Jhan Carlo; Martinez, Jean-Michel; Guyot, Jean-Loup; Lagane, Christelle; Filizola, Naziano; Noriega, Luis; Hidalgo Sanchez, Liz; Pombosa, Rodrigo

2017-11-01

Large hydrological systems aggregate compositionally different waters derived from a variety of pathways. In the case of continental-scale rivers, such aggregation occurs noticeably at confluences between tributaries. Here we explore how such aggregation can affect solute concentration-discharge (C-Q) relationships and thus obscure the message carried by these relationships in terms of weathering properties of the Critical Zone. We build up a simple model for tributary mixing to predict the behavior of C-Q relationships during aggregation. We test a set of predictions made in the context of the largest world's river, the Amazon. In particular, we predict that the C-Q relationships of the rivers draining heterogeneous catchments should be the most "dilutional" and should display the widest hysteresis loops. To check these predictions, we compute 10 day-periodicity time series of Q and major solute (Si, Ca2+, Mg2+, K+, Na+, Cl-, SO42-) C and fluxes (F) for 13 gauging stations located throughout the Amazon basin. In agreement with the model predictions, C-Q relationships of most solutes shift from a fairly "chemostatic" behavior (nearly constant C) at the Andean mountain front and in pure lowland areas, to more "dilutional" patterns (negative C-Q relationship) toward the system mouth. More prominent C-Q hysteresis loops are also observed at the most downstream stations. Altogether, this study suggests that mixing of water and solutes between different flowpaths exerts a strong control on C-Q relationships of large-scale hydrological systems.

River ecosystem response to prescribed vegetation burning on Blanket Peatland.

PubMed

Brown, Lee E; Johnston, Kerrylyn; Palmer, Sheila M; Aspray, Katie L; Holden, Joseph

2013-01-01

Catchment-scale land-use change is recognised as a major threat to aquatic biodiversity and ecosystem functioning globally. In the UK uplands rotational vegetation burning is practised widely to boost production of recreational game birds, and while some recent studies have suggested burning can alter river water quality there has been minimal attention paid to effects on aquatic biota. We studied ten rivers across the north of England between March 2010 and October 2011, five of which drained burned catchments and five from unburned catchments. There were significant effects of burning, season and their interaction on river macroinvertebrate communities, with rivers draining burned catchments having significantly lower taxonomic richness and Simpson's diversity. ANOSIM revealed a significant effect of burning on macroinvertebrate community composition, with typically reduced Ephemeroptera abundance and diversity and greater abundance of Chironomidae and Nemouridae. Grazer and collector-gatherer feeding groups were also significantly less abundant in rivers draining burned catchments. These biotic changes were associated with lower pH and higher Si, Mn, Fe and Al in burned systems. Vegetation burning on peatland therefore has effects beyond the terrestrial part of the system where the management intervention is being practiced. Similar responses of river macroinvertebrate communities have been observed in peatlands disturbed by forestry activity across northern Europe. Finally we found river ecosystem changes similar to those observed in studies of wild and prescribed forest fires across North America and South Africa, illustrating some potentially generic effects of fire on aquatic ecosystems.

Predicted Exposures to Steroid Estrogens in U.K. Rivers Correlate with Widespread Sexual Disruption in Wild Fish Populations

PubMed Central

Jobling, Susan; Williams, Richard; Johnson, Andrew; Taylor, Ayesha; Gross-Sorokin, Melanie; Nolan, Monique; Tyler, Charles R.; van Aerle, Ronny; Santos, Eduarda; Brighty, Geoff

2006-01-01

Steroidal estrogens, originating principally from human excretion, are likely to play a major role in causing widespread endocrine disruption in wild populations of the roach (Rutilus rutilus), a common cyprinid fish, in rivers contaminated by treated sewage effluents. Given the extent of this problem, risk assessment models are needed to predict the location and severity of endocrine disruption in river catchments and to identify areas where regulation of sewage discharges to remove these contaminants is necessary. In this study we attempted to correlate the extent of endocrine disruption in roach in British rivers, with their predicted exposure to steroid estrogens derived from the human population. The predictions of steroid estrogen exposure at each river site were determined by combining the modeled concentrations of the individual steroid estrogens [17β -estradiol (E2), estrone (E1), and 17α -ethinylestradiol (EE2)] in each sewage effluent with their predicted dilution in the immediate receiving water. This model was applied to 45 sites on 39 rivers throughout the United Kingdom. Each site studied was then categorized as either high, medium, or low “risk” on the basis of the assumed additive potency of the three steroid estrogens calculated from data derived from published studies in various cyprinid fish species. We sampled 1,438 wild roach from the predicted high-, medium-, and low-risk river sites and examined them for evidence and severity of endocrine disruption. Both the incidence and the severity of intersex in wild roach were significantly correlated with the predicted concentrations of the natural estrogens (E1 and E2) and the synthetic contraceptive pill estrogen (EE2) present. Predicted steroid estrogen exposure was, however, less well correlated with the plasma vitellogenin concentration measured in the same fish. Moreover, we found no correlation between any of the end points measured in the roach and the proportion of industrial effluents

Assessing the combined effects of urbanisation and climate change on the river water quality in an integrated urban wastewater system in the UK.

PubMed

Astaraie-Imani, Maryam; Kapelan, Zoran; Fu, Guangtao; Butler, David

2012-12-15

Climate change and urbanisation are key factors affecting the future of water quality and quantity in urbanised catchments and are associated with significant uncertainty. The work reported in this paper is an evaluation of the combined and relative impacts of climate change and urbanisation on the receiving water quality in the context of an Integrated Urban Wastewater System (IUWS) in the UK. The impacts of intervening system operational control parameters are also investigated. Impact is determined by a detailed modelling study using both local and global sensitivity analysis methods together with correlation analysis. The results obtained from the case-study analysed clearly demonstrate that climate change combined with increasing urbanisation is likely to lead to worsening river water quality in terms of both frequency and magnitude of breaching threshold dissolved oxygen and ammonium concentrations. The results obtained also reveal the key climate change and urbanisation parameters that have the largest negative impact as well as the most responsive IUWS operational control parameters including major dependencies between all these parameters. This information can be further utilised to adapt future IUWS operation and/or design which, in turn, should make these systems more resilient to future climate and urbanisation changes. Copyright © 2012 Elsevier Ltd. All rights reserved.

Some aspects of water quality in a polluted lowland river in relation to the intracellular chemical levels in planktonic and epilithic diatoms.

PubMed

Tien, Chien-Jung

2004-04-01

Changes in elemental concentrations of diatoms and river water from the river Erh-Jen were determined using scanning electron microscopy energy-dispersive X-ray microanalysis and inductively coupled plasma mass spectrometry. Relatively large amounts of copper and lead found in both planktonic and epilithic diatoms implied these algae might play an important role in biogeochemical cycles and in the transfer of those elements to higher trophic levels in the aquatic environment. Changes in elemental concentrations within diatom cells were found to vary with other elements within cells and the same or different elements in water. Planktonic and epilithic cells showed different correlation patterns. For epilithic diatoms, negative correlations were found between concentrations of total phosphorus and phosphate in water and those of phosphorus within cells, and between concentrations of lead in water and in cells. Concentrations of chromium and mercury within planktonic cells and those of phosphorus, manganese and lead within epilithic ones were found to be easily influenced by other elements in river water, indicating appearance of the competitive manner on uptake of such elements by algal cells. Relatively high concentration factors (CFs) for cadmium, mercury and lead by diatoms in this study suggested they are good accumulators for these heavy metals. Significant negative corrections were found between the CFs of diatoms and the concentrations of elements in river water.

The Land Remembers: Landscape Terms and Place Names in Lowland Chontal of Oaxaca, Mexico

ERIC Educational Resources Information Center

O'Connor, Loretta; Kroefges, Peter C.

2008-01-01

This paper examines landscape terminology and place names of the Chontal region in the state of Oaxaca in southern Mexico, with a focus on terms from Lowland Chontal, a highly endangered language spoken near the Pacific coast. In addition to the linguistic analysis, the paper presents a general description of the physical geography of the area and…

Radar mapping, archaeology, and ancient land use in the Maya lowlands

NASA Technical Reports Server (NTRS)

Adams, R. E. W.; Brown, W. E., Jr.; Culbert, T. P.

1981-01-01

Data from the use of synthetic aperture radar in aerial survey of the southern Maya lowlands suggest the presence of very large areas drained by ancient canals for the purpose of intensive cultivation. Preliminary ground checks in several very limited areas confirm the existence of canals and raised fields. Excavations and ground surveys by several scholars provide valuable comparative information. Taken together, the new data suggest that Late Classic period Maya civilization was firmly grounded in large-scale and intensive cultivation of swampy zones.

Climate Change in Lowland Central America During the Late Deglacial and Early Holocene

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

Hillesheim, M B; Hodell, D A; Leyden, B W

2005-02-08

The transition from arid glacial to moist early Holocene conditions represented a profound change in northern lowland Neotropical climate. Here we report a detailed record of changes in moisture availability during the latter part of this transition ({approx}11,250 to 7,500 cal yr BP) inferred from sediment cores retrieved in Lake Peten Itza, northern Guatemala. Pollen assemblages demonstrate that a mesic forest had been largely established by {approx}11,250 cal yr BP, but sediment properties indicate that lake level was more than 35 m below modern stage. From 11,250 to 10,350 cal yr BP, during the Preboreal period, lithologic changes in sedimentsmore » from deep-water cores (>50 m below modern water level) indicate several wet-dry cycles that suggest distinct changes in effective moisture. Four dry events (designated PBE1-4) occurred at 11,200, 10,900, 10,700, and 10,400 cal yr BP and correlate with similar variability observed in the Cariaco Basin titanium record and glacial meltwater pulses into the Gulf of Mexico. After 10,350 cal yr BP, multiple sediment proxies suggest a shift to a more persistently moist early Holocene climate. Comparison of results from Lake Peten Itza with other records from the circum-Caribbean demonstrates a coherent climate response during the entire span of our record. Furthermore, lowland Neotropical climate during the late deglacial and early Holocene period appears to be tightly linked to climate change in the high-latitude North Atlantic. We speculate that the observed changes in lowland Neotropical precipitation were related to the intensity of the annual cycle and associated displacements in the mean latitudinal position of the Intertropical Convergence Zone and Azores-Bermuda high-pressure system. This mechanism operated on millennial-to-submillennial timescales and may have responded to changes in solar radiation, glacial meltwater, North Atlantic sea ice, and the Atlantic meridional overturning circulation (MOC).« less

Benchmarking hydrological model predictive capability for UK River flows and flood peaks.

NASA Astrophysics Data System (ADS)

Lane, Rosanna; Coxon, Gemma; Freer, Jim; Wagener, Thorsten

2017-04-01

Data and hydrological models are now available for national hydrological analyses. However, hydrological model performance varies between catchments, and lumped, conceptual models are not able to produce adequate simulations everywhere. This study aims to benchmark hydrological model performance for catchments across the United Kingdom within an uncertainty analysis framework. We have applied four hydrological models from the FUSE framework to 1128 catchments across the UK. These models are all lumped models and run at a daily timestep, but differ in the model structural architecture and process parameterisations, therefore producing different but equally plausible simulations. We apply FUSE over a 20 year period from 1988-2008, within a GLUE Monte Carlo uncertainty analyses framework. Model performance was evaluated for each catchment, model structure and parameter set using standard performance metrics. These were calculated both for the whole time series and to assess seasonal differences in model performance. The GLUE uncertainty analysis framework was then applied to produce simulated 5th and 95th percentile uncertainty bounds for the daily flow time-series and additionally the annual maximum prediction bounds for each catchment. The results show that the model performance varies significantly in space and time depending on catchment characteristics including climate, geology and human impact. We identify regions where models are systematically failing to produce good results, and present reasons why this could be the case. We also identify regions or catchment characteristics where one model performs better than others, and have explored what structural component or parameterisation enables certain models to produce better simulations in these catchments. Model predictive capability was assessed for each catchment, through looking at the ability of the models to produce discharge prediction bounds which successfully bound the observed discharge. These results

Anthropogenic greenhouse gas contribution to UK autumn flood risk

NASA Astrophysics Data System (ADS)

Pall, Pardeep; Aina, Tolu; Stone, Dáithí; Stott, Peter; Nozawa, Toru; Hilberts, Arno; Lohmann, Dag; Allen, Myles

2010-05-01

Interest in attributing the risk of damaging weather-related events to anthropogenic climate change is increasing[1]. Yet climate models typically used for studying the attribution problem do not resolve weather at scales causing damage[2]. Here we present the first multi-step study that attributes increasing risk of a damaging regional weather-related event to global anthropogenic greenhouse gas emissions. The event was the UK flooding of October and November 2000, occurring during the wettest autumn in England & Wales since records began in 1766[3] and inundating several river catchments[4]. Nearly 10,000 properties were flooded and transport services and power supplies severely disrupted, with insured losses estimated at £1.3bn[5,6]. Though the floods were deemed a ‘wake up call' to the impacts of climate change[7], anthropogenic drivers cannot be blamed for this individual event: but they could be blamed for changing its risk[8,9]. Indeed, typically quoted thermodynamic arguments do suggest increased probability of precipitation extremes under anthropogenic warming[10]. But these arguments are too simple[11,12,13] to fully account for the complex weather[4,14] associated with the flooding. Instead we use a Probabilistic Event Attribution framework, to rigorously estimate the contribution of anthropogenic greenhouse gas emissions to England & Wales Autumn 2000 flood risk. This involves comparing an unprecedented number of daily river runoff realisations for the region, under Autumn 2000 scenarios both with and without the emissions. These realisations are produced using publicly volunteered distributed computing power to generate several thousand seasonal forecast resolution climate model simulations[15,16] that are then fed into a precipitation-runoff model[17,18]. Autumn 2000 flooding is characterised by realisations exceeding the highest daily river runoff for that period, derived from the observational-based ERA-40 re-anaylsis[19]. We find that our

Surface-Water Quality of the Skokomish, Nooksack, and Green-Duwamish Rivers and Thornton Creek, Puget Sound Basin, Washington, 1995-98

USGS Publications Warehouse

Embrey, S.S.; Frans, L.M.

2003-01-01

inches fell (about 14 inches above average) and monthly precipitation was often 200 percent of normal. The wet years kept streamflows generally above normal and contributed to high concentrations of pesticides, nutrients, suspended sediment, and organic carbon in samples. On the basis of chemical concentrations, dissolved oxygen concentrations, and water temperature, the relative quality of water among the 11 study sites ranged from exceptionally high in the North Fork Skokomish and the Green to fair in Springbrook and Thornton. Water in the large rivers (Skokomish, Nooksack, Green-Duwamish) and in two of the small streams in the Puget Sound Lowlands (Big Soos and Newaukum) was characterized by dilute water chemistry with dissolved solids concentrations less than 130 milligrams per liter. Water in three other small streams in the Lowlands (Fishtrap, Springbrook, and Thornton) had dissolved solids concentrations as high as 320 milligrams per liter. Nutrient and pesticide concentrations mostly were higher in the small streams than in the large rivers. Suspended-sediment concentrations, however, were highest in the large rivers, with averages ranging from 85 to 443 milligrams per liter. During storm and flood events, suspended-sediment concentrations in samples from the Nooksack were as much as 2,800 milligrams per liter, and from the Skokomish, 1,500 milligrams per liter. Out of 86 pesticides and 86 volatile organic compounds analyzed, a total of 35 pesticides and 11 volatile organic compounds were detected at concentrations above laboratory reporting levels in samples collected from the four intensively studied sites, the lower Nooksack River, Duwamish River, Fishtrap Creek, and Thornton Creek. Herbicides were detected more frequently than insecticides. The herbicide prometon was detected in 66 percent of all 124 samples collected, followed by simazine (65 percent), atrazine (64 percent), and the insecticide diazinon (50 percent). The detected volatile organic c

Leaf-level photosynthetic capacity in lowland Amazonian and high-elevation Andean tropical moist forests of Peru.

PubMed

Bahar, Nur H A; Ishida, F Yoko; Weerasinghe, Lasantha K; Guerrieri, Rossella; O'Sullivan, Odhran S; Bloomfield, Keith J; Asner, Gregory P; Martin, Roberta E; Lloyd, Jon; Malhi, Yadvinder; Phillips, Oliver L; Meir, Patrick; Salinas, Norma; Cosio, Eric G; Domingues, Tomas F; Quesada, Carlos A; Sinca, Felipe; Escudero Vega, Alberto; Zuloaga Ccorimanya, Paola P; Del Aguila-Pasquel, Jhon; Quispe Huaypar, Katherine; Cuba Torres, Israel; Butrón Loayza, Rosalbina; Pelaez Tapia, Yulina; Huaman Ovalle, Judit; Long, Benedict M; Evans, John R; Atkin, Owen K

2017-05-01

We examined whether variations in photosynthetic capacity are linked to variations in the environment and/or associated leaf traits for tropical moist forests (TMFs) in the Andes/western Amazon regions of Peru. We compared photosynthetic capacity (maximal rate of carboxylation of Rubisco (V cmax ), and the maximum rate of electron transport (J max )), leaf mass, nitrogen (N) and phosphorus (P) per unit leaf area (M a , N a and P a , respectively), and chlorophyll from 210 species at 18 field sites along a 3300-m elevation gradient. Western blots were used to quantify the abundance of the CO 2 -fixing enzyme Rubisco. Area- and N-based rates of photosynthetic capacity at 25°C were higher in upland than lowland TMFs, underpinned by greater investment of N in photosynthesis in high-elevation trees. Soil [P] and leaf P a were key explanatory factors for models of area-based V cmax and J max but did not account for variations in photosynthetic N-use efficiency. At any given N a and P a , the fraction of N allocated to photosynthesis was higher in upland than lowland species. For a small subset of lowland TMF trees examined, a substantial fraction of Rubisco was inactive. These results highlight the importance of soil- and leaf-P in defining the photosynthetic capacity of TMFs, with variations in N allocation and Rubisco activation state further influencing photosynthetic rates and N-use efficiency of these critically important forests. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

The UK geochemical environment and cardiovascular diseases: magnesium in food and water.

PubMed

Davies, B E

2015-06-01

Cardiovascular diseases (CVDs) contribute approximately one-third to noncommunicable diseases in the UK. The central role of magnesium in CVDs (enzyme activity, cardiac signalling, etc.) is well established. Mortality and morbidity rates for CVDs may be inversely related to water hardness, suggesting a role for environmental magnesium. Published official and quasi-official data sources were evaluated to establish a model magnesium intake for a representative adult: standardised reference individual (SRI), standardised reference male (SRM) or standardised reference female (SRF). For typical dietary constituents, only tap water is probably locally derived and bottled water may not be. Fruits and vegetables are imported from many countries, while meat, dairy and cereal products represent a composite of UK source areas. Alcoholic beverages provide magnesium, there is doubt about its absorptive efficiency, and they are not locally derived. A simple model was devised to examine the effect of varying dietary contributions to total daily intake of magnesium. Omitting tap or bottled water, the combined intake, solid food plus alcoholic beverages, is 10.57 mmol Mg (84.5 % RNI) for the SRM and for the SRF, 8.10 mmol Mg (71.7 % RNI). Consumers drinking water derived from reservoirs or rivers, or supplementing it with the purest bottled water, improve their magnesium intake only slightly compared with water containing no magnesium. Choosing bottled water with high magnesium content when the public supply derives from rivers or reservoirs partially satisfies magnesium needs. Real improvement in SRI magnesium nutrition is seen only where water is hard. However, this conclusion cannot be validated until new measurement technologies for body magnesium become available.

Lowland forest loss in protected areas of Indonesian Borneo.

PubMed

Curran, L M; Trigg, S N; McDonald, A K; Astiani, D; Hardiono, Y M; Siregar, P; Caniago, I; Kasischke, E

2004-02-13

The ecology of Bornean rainforests is driven by El Niño-induced droughts that trigger synchronous fruiting among trees and bursts of faunal reproduction that sustain vertebrate populations. However, many of these species- and carbon-rich ecosystems have been destroyed by logging and conversion, which increasingly threaten protected areas. Our satellite, Geographic Information System, and field-based analyses show that from 1985 to 2001, Kalimantan's protected lowland forests declined by more than 56% (>29,000 square kilometers). Even uninhabited frontier parks are logged to supply international markets. "Protected" forests have become increasingly isolated and deforested and their buffer zones degraded. Preserving the ecological integrity of Kalimantan's rainforests requires immediate transnational management.

Reye's or Reye's-like syndrome in western lowland gorilla (Gorilla gorilla gorilla).

PubMed

Minter, Larry J; Cullen, John M; Loomis, Michael R

2012-10-01

A 15-year-old western lowland gorilla (Gorilla gorilla gorilla) died shortly after transfer to the North Carolina Zoo. Complete blood count, serum biochemical analysis, and necropsy were performed. Combination of compatible clinical signs, biochemical and histopathological findings fulfilled all of the CDC definition criteria of Reye's or a Reye's like syndrome. This report describes a case of Reye's syndrome or Reye's-like syndrome in a non-human primate. © 2012 John Wiley & Sons A/S.

Development of sedentary communities in the Maya lowlands: coexisting mobile groups and public ceremonies at Ceibal, Guatemala.

PubMed

Inomata, Takeshi; MacLellan, Jessica; Triadan, Daniela; Munson, Jessica; Burham, Melissa; Aoyama, Kazuo; Nasu, Hiroo; Pinzón, Flory; Yonenobu, Hitoshi

2015-04-07

Our archaeological investigations at Ceibal, a lowland Maya site located in the Pasión region, documented that a formal ceremonial complex was built around 950 B.C. at the onset of the Middle Preclassic period, when ceramics began to be used in the Maya lowlands. Our refined chronology allowed us to trace the subsequent social changes in a resolution that had not been possible before. Many residents of Ceibal appear to have remained relatively mobile during the following centuries, living in ephemeral post-in-ground structures and frequently changing their residential localities. In other parts of the Pasión region, there may have existed more mobile populations who maintained the traditional lifestyle of the preceramic period. Although the emerging elite of Ceibal began to live in a substantial residential complex by 700 B.C., advanced sedentism with durable residences rebuilt in the same locations and burials placed under house floors was not adopted in most residential areas until 500 B.C., and did not become common until 300 B.C. or the Late Preclassic period. During the Middle Preclassic period, substantial formal ceremonial complexes appear to have been built only at a small number of important communities in the Maya lowlands, and groups with different levels of sedentism probably gathered for their constructions and for public rituals held in them. These collaborative activities likely played a central role in socially integrating diverse groups with different lifestyles and, eventually, in developing fully established sedentary communities.

Seed germination from lowland tapir (Tapirus terrestris) fecal samples collected during the dry season in the Northern Brazilian Amazon.

PubMed

Barcelos, Adriana Renata; Bobrowiec, Paulo Estefano D; Sanaiotti, Tânia Margarete; Gribel, Rogério

2013-03-01

This study evaluated the potential of lowland tapirs as seed dispersers in the northern Brazilian Amazon. The study analyzed the viability of seeds after passage through the gut. Fecal samples were collected from 6 different vegetation physiognomies in Viruá National Park during the dry season. The samples were then kept in a greenhouse for 16 months to allow the seeds to germinate. The seedling species were identified and classified according to the type of fruit, plant habit, seed size and type of ingestion. Of the 111 fecal samples, 94 (84.7%) had viable seeds of 75 species. Melastomataceae was the most frequent family with viable seeds in the fecal samples (69.1% of samples, N= 18 species). The data suggest that the importance of the lowland tapirs as dispersers is not restricted to the species consumed actively by frugivory but also extends to species accidentally consumed during browsing. The occurrence of both large and small viable seeds in the fecal samples as well as a number of large drupes, which probably cannot be transported via endozoochory by any other animal species, provide evidence of the ecological importance of lowland tapirs to the dynamics of the forest-campinarana vegetation mosaic in the region. © 2012 Wiley Publishing Asia Pty Ltd, ISZS and IOZ/CAS.

Herpetofaunal assemblages of a lowland broadleaf forest, an overgrown orchard forest and a lime orchard in Stann Creek, Belize

PubMed Central

Gray, Russell; Strine, Colin T.

2017-01-01

Abstract Understanding and monitoring ecological impacts of the expanding agricultural industry in Belize is an important step in conservation action. To compare possible alterations in herpetofaunal communities due to these anthropogenic changes, trapping arrays were set in a manicured orchard, a reclaimed orchard and a lowland broadleaf forest in Stann Creek district at Toucan Ridge Ecology and Education Society (TREES). Trapping efforts were carried out during the rainy season, from June to September, 2016, during which time the study site was hit by a category one hurricane between sampling sessions. Trapping yielded 197 individual herpetofauna and 40 different species overall; 108 reptile captures (30 species) and 88 amphibian captures (ten species). Reptiles and amphibians were more abundant in the lowland broadleaf forest and the manicured orchard area. Amphibian species diversity was relatively similar in each habitat type. Reptile captures were most diverse in the Overgrown Orchard Forest (OGF) and Overgrown Orchard Riparian Forest (OGR) and least diverse in the Lowland Broadleaf Forest (LBF). The findings of this study suggest that reptile and amphibian sensitivity to anthropogenically altered areas is minimal when enveloped by natural habitat buffers, and additionally, that extreme weather events have little impact on herpetofauna communities in the area. PMID:29118630

Human impact on long-term organic carbon export to rivers

NASA Astrophysics Data System (ADS)

Noacco, Valentina; Wagener, Thorsten; Worrall, Fred; Burt, Tim P.; Howden, Nicholas J. K.

2017-04-01

Anthropogenic landscape alterations have increased global carbon transported by rivers to oceans since preindustrial times. Few suitable observational data sets exist to distinguish different drivers of carbon increase, given that alterations only reveal their impact on fluvial dissolved organic carbon (DOC) over long time periods. We use the world's longest record of DOC concentrations (130 years) to identify key drivers of DOC change in the Thames basin (UK). We show that 90% of the long-term rise in fluvial DOC is explained by increased urbanization, which released to the river 671 kt C over the entire period. This source of carbon is linked to rising population, due to increased sewage effluent. Soil disturbance from land use change explained shorter-term fluvial responses. The largest land use disturbance was during the Second World War, when almost half the grassland area in the catchment was converted into arable land, which released 45 kt C from soils to the river. Carbon that had built up in soils over decades was released to the river in only a few years. Our work suggests that widespread population growth may have a greater influence on fluvial DOC trends than previously thought.

An evaluation of public participation in UK river basin management planning

NASA Astrophysics Data System (ADS)

Schmid, M.; Benson, D.

2012-04-01

The EU Water Framework Directive is reshaping multi-level environmental governance structures in many Member States. One area where re-structuring should be highly visible is in regards to public participation in water management. The Directive legally mandates that implementing agencies should make information publicly available relating to river basin management planning, include the public in the planning process and encourage the active involvement of 'interested parties' both during and after the planning stage. Yet critical questions arise over the extent to which these requirements have actually been met in Member States and the outcomes of participatory processes on the ground. In this study, public participation was evaluated in England and Wales by conducting: a) a broad based quantitative survey of the implementation strategy undertaken across all 11 River Basin Districts (RBDs); and, b) an in-depth analysis of the Anglian RBD drawing on theoretical notions of social learning; a critical measure of participatory processes. Results from the survey showed all RBDs complied with the minimum regulatory requirements on public access to information and written consultation, and even went further with provisions for oral consultation and stakeholder engagement. But the focus was clearly on stakeholder groups with little public involvement beyond minimal legally mandated requirements. Analysis of case study data provided some evidence of social learning at every level (instrumental, communicative and transformative) and beyond the individual scale (wider community and organisational learning). Learning was however significantly limited by participant's high level of expertise and environmental awareness. Also apparent was the influence of other factors, operating at various institutional scales, in shaping learning. The paper then speculates on the implications of the findings for both future research and policy, particularly in light of the European Commission

The Impact of Rise of the Andes and Amazon Landscape Evolution on Diversification of Lowland terra-firme Forest Birds

NASA Technical Reports Server (NTRS)

Aleixo, Alexandre; Wilkinson, M. Justin

2011-01-01

Since the 19th Century, the unmatched biological diversity of Amazonia has stimulated a diverse set of hypotheses accounting for patterns of species diversity and distribution in mega-diverse tropical environments. Unfortunately, the evidence supporting particular hypotheses to date is at best described as ambiguous, and no generalizations have emerged yet, mostly due to the lack of comprehensive comparative phylogeographic studies with thorough trans-Amazonian sampling of lineages. Here we report on spatial and temporal patterns of diversification estimated from mitochondrial gene trees for 31 lineages of birds associated with upland terra-firme forest, the dominant habitat in modern lowland Amazonia. The results confirm the pervasive role of Amazonian rivers as primary barriers separating sister lineages of birds, and a protracted spatio-temporal pattern of diversification, with a gradual reduction of earlier (1st and 2nd) and older (> 2 mya) splits associated with each lineage in an eastward direction. (The easternmost tributaries of the Amazon, the Xingu and Tocantins Rivers, are not associated with any splits older than > 2 mya). For the suboscine passerines, maximum-likelihood estimates of rates of diversification point to an overall constant rate over the past 5 my (up to a significant downturn at 300,000 y ago). This "younging-eastward" pattern may have an abiotic explanation related to landscape evolution. Triggered by a new pulse of Andean uplift, it has been proposed that modern Amazon basin landscapes may have evolved successively eastward, away from the mountain chain, starting approximately 10 mya. This process was likely based on the deposition of vast fluvial sediment masses, known as megafans, that may have extended progressively and in series eastward from Andean sources. This process plausibly explains the progressive extinction of original Pebas wetland of western-central Amazonia by the present fluvial landsurfaces of a more terra-firme type

Long-term accumulation and transport of anthropogenic phosphorus in three river basins

NASA Astrophysics Data System (ADS)

Powers, Stephen M.; Bruulsema, Thomas W.; Burt, Tim P.; Chan, Neng Iong; Elser, James J.; Haygarth, Philip M.; Howden, Nicholas J. K.; Jarvie, Helen P.; Lyu, Yang; Peterson, Heidi M.; Sharpley, Andrew N.; Shen, Jianbo; Worrall, Fred; Zhang, Fusuo

2016-05-01

Global food production depends on phosphorus. Phosphorus is broadly applied as fertilizer, but excess phosphorus contributes to eutrophication of surface water bodies and coastal ecosystems. Here we present an analysis of phosphorus fluxes in three large river basins, including published data on fertilizer, harvested crops, sewage, food waste and river fluxes. Our analyses reveal that the magnitude of phosphorus accumulation has varied greatly over the past 30-70 years in mixed agricultural-urban landscapes of the Thames Basin, UK, the Yangtze Basin, China, and the rural Maumee Basin, USA. Fluxes of phosphorus in fertilizer, harvested crops, food waste and sewage dominate over the river fluxes. Since the late 1990s, net exports from the Thames and Maumee Basins have exceeded inputs, suggesting net mobilization of the phosphorus pool accumulated in earlier decades. In contrast, the Yangtze Basin has consistently accumulated phosphorus since 1980. Infrastructure modifications such as sewage treatment and dams may explain more recent declines in total phosphorus fluxes from the Thames and Yangtze Rivers. We conclude that human-dominated river basins may undergo a prolonged but finite accumulation phase when phosphorus inputs exceed agricultural demand, and this accumulated phosphorus may continue to mobilize long after inputs decline.

Hydrogeologic framework and selected components of the groundwater budget for the upper Umatilla River Basin, Oregon

USGS Publications Warehouse

Herrera, Nora B.; Ely, Kate; Mehta, Smita; Stonewall, Adam J.; Risley, John C.; Hinkle, Stephen R.; Conlon, Terrence D.

2017-05-31

Executive SummaryThis report presents a summary of the hydrogeology of the upper Umatilla River Basin, Oregon, based on characterization of the hydrogeologic framework, horizontal and vertical directions of groundwater flow, trends in groundwater levels, and components of the groundwater budget. The conceptual model of the groundwater flow system integrates available data and information on the groundwater resources of the upper Umatilla River Basin and provides insights regarding key hydrologic processes, such as the interaction between the groundwater and surface water systems and the hydrologic budget.The conceptual groundwater model developed for the study area divides the groundwater flow system into five hydrogeologic units: a sedimentary unit, three Columbia River basalt units, and a basement rock unit. The sedimentary unit, which is not widely used as a source of groundwater in the upper basin, is present primarily in the lowlands and consists of conglomerate, loess, silt and sand deposits, and recent alluvium. The Columbia River Basalt Group is a series of Miocene flood basalts that are present throughout the study area. The basalt is uplifted in the southeastern half of the study area, and either underlies the sedimentary unit, or is exposed at the surface. The interflow zones of the flood basalts are the primary aquifers in the study area. Beneath the flood basalts are basement rocks composed of Paleogene to Pre-Tertiary sedimentary, volcanic, igneous, and metamorphic rocks that are not used as a source of groundwater in the upper Umatilla River Basin.The major components of the groundwater budget in the upper Umatilla River Basin are (1) groundwater recharge, (2) groundwater discharge to surface water and wells, (3) subsurface flow into and out of the basin, and (4) changes in groundwater storage.Recharge from precipitation occurs primarily in the upland areas of the Blue Mountains. Mean annual recharge from infiltration of precipitation for the upper

Environmental factors-ecological species group relationships in the Surash lowland-mountain forests in northern Iran

Treesearch

Fatemeh Bazdid Vahdati; Shahryar Saeidi Mehrvarz; Daniel C. Dey; Alireza Naqinezhad

2016-01-01

Identification of the primary factors that influence the ecological distribution of species groups is important to managers of lowland-mountain forests in northern Iran. The aim of this study was to identify main ecological species groups, describe the site conditions associated with these species groups and the relationships between environmental factors and the...

Developing a Global Network of River Reaches in Preparation of SWOT

NASA Astrophysics Data System (ADS)

Lion, C.; Pavelsky, T.; Allen, G. H.; Beighley, E.; Schumann, G.; Durand, M. T.

2016-12-01

In 2020, the Surface Water and Ocean Topography satellite (SWOT), a joint mission of NASA/CNES/CSA/UK will be launched. One of its major products will be the measurements of continental water surfaces, including the width, height, and slope of rivers and the surface area and elevations of lakes. The mission will improve the monitoring of continental water and also our understanding of the interactions between different hydrologic reservoirs. For rivers, SWOT measurements of slope will be carried out over predefined river reaches. As such, an a priori dataset for rivers is needed in order to facilitate analysis of the raw SWOT data. The information required to produce this dataset includes measurements of river width, elevation, slope, planform, river network topology, and flow accumulation. To produce this product, we have linked two existing global datasets: the Global River Widths from Landsat (GRWL) database, which contains river centerline locations, widths, and a braiding index derived from Landsat imagery, and a modified version of the HydroSHEDS hydrologically corrected digital elevation product, which contains heights and flow accumulation measurements for streams at 3 arcseconds spatial resolution. Merging these two datasets requires considerable care. The difficulties, among others, lie in the difference of resolution: 30m versus 3 arseconds, and the age of the datasets: 2000 versus 2010 (some rivers have moved, the braided sections are different). As such, we have developed custom software to merge the two datasets, taking into account the spatial proximity of river channels in the two datasets and ensuring that flow accumulation in the final dataset always increases downstream. Here, we present our results for the globe.

CATS landline installed beneath the river Tees

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

Not Available

Press Construction Ltd. has completed installation of the land portion of a new gas pipeline from the North Sea, including a tunnel beneath the River Tees in the north of England. The work was carried out under a multi-million dollar contract from Amoco (UK) Exploration Co. The pipeline is the land portion of the Central Area Transmission System. The 4.6-mile, 36-in. onshore pipeline connects a valve station at the CATS landfall at Coatham Sands, just south of Tees Bay, to a gas terminal north of the River Tees. This paper reports on the entire CATS system which runs for nearlymore » 250 miles from a riser platform in the Central Graben area of the North Sea to the Coatham Sands landfall and then overland to the gas terminal. The gas will fuel a new combined heat-and-power generating plant on Teesside, currently under construction by Teesside Power.« less

Ecosystem and restoration consequences of invasive woody species removal in Hawaiian lowland wet forest

Treesearch

R. Ostertag; S. Cordell; J. Michaud; T.C. Cole; J.R. Schulten; K.M. Publico; J.H. Enoka

2009-01-01

A removal experiment was used to examine the restoration potential of a lowland wet forest in Hawaii, a remnant forest type that has been heavily invaded by non-native species and in which there is very little native species regeneration. All non-native woody and herbaceous biomass (approximately 45% of basal area) was removed in four 100-m² removal plots;...

Interpretation of gravity anomalies in the northwest Adirondack lowlands, northern New York

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

Revetta, F.A.; O'Brian, B.

1993-03-01

Twelve hundred gravity measurements were made in the Adirondack Highlands and northwest Adirondack Lowlands, New York between 44[degree]15 minutes and 44[degree]30 minutes N. Latitude and 75[degree]00 minutes W. Longitude. A Bouguer gravity map constructed from the gravity measurements includes the Carthage-Colton Mylonite Zone, a major structural boundary between the highlands and lowlands. The gravity map indicates the gravity contours trend parallel to the CCMZ along most of its length however in some areas the contours cross the boundary. No clear-cut relationships exists between the CCMZ and gravity contours. The Bouguer gravity map shows several prominent gravity anomalies which correlate withmore » the geology seismicity and mineral deposits in the area. Gravity lows of 20 to 30 g.u. are centered over the Gouverneur, Hyde and Payne Lake Alaskite gneiss bodies. A gravity high of 20 g.u. occurs over the Pleasant Lake gabbro pluton. Gravity highs of 35 and 100 g.u. occur over the Sylvia Lake Zinc District and marble just north of the district. A gravity high at Russell, N.Y. coincides with a cluster of nine earthquake epicenters. Finally a steep gravity gradient separates high density rocks from lower density rocks along the Black Lake fault. Two-dimensional computer modeling of the geologic features is underway and quantitative models of the structures will be presented.« less

The Hydroclimatic Response of the Whitewater River Basin: Influence of Groundwater Time Scales

NASA Astrophysics Data System (ADS)

Beeson, P. C.; Springer, E. P.; Duffy, C. J.

2003-12-01

A near-surface groundwater model was developed to assess the impact of land use and climate variability on the overall water budget of the Whitewater River Basin. The watershed is located in southeastern Kansas within the ARM-SGP as part of the DOE Water Cycle Pilot Study. The Whitewater River Basin has an area of 1,100 square-kilometers, an elevation range of 380 - 470m (amsl), and an average annual precipitation of 858 millimeters. The approach presented here attempts to examine the importance of groundwater in the water budget and hydroclimatic response at the river basin scale. In order to identify the time scales of groundwater in this system, time series and geospatial analyses were used to identify significant spatial structure and dominant temporal modes in the climate, runoff and groundwater response. In this research, we show that the time scales of groundwater baseflow to the river network are proportional to drainage density and position in the hydrologic landscape. The concept of a hydrologic landscape (Winter, JAWRA, April 2001) defines three zones: recharge (upland), translation (intervening steep slopes), and discharge (lowland), and the hydrologic landscape is useful for standardizing the evaluation of physical properties within any watershed. Singular spectrum analysis was used for a 50-year simulation to determine dominant modes and time scales for the hydrologic landscape units in the Whitewater River Basin. We found that the time scale of groundwater baseflow response increases with increasing drainage density. The sensitivity of this response is important to understand and close the water budget for a river basin through observation network design. The effects of climate forcing, both precipitation and evapotranspiration, can be seen through the hydrologic landscapes and channel networks by changes in the baseflow response time. Los Alamos National Laboratory, an affirmative action/equal opportunity employer, is operated by the University of

Geomorphic and substrate controls on spatial variability in river solute transport and biogeochemical cycling

NASA Astrophysics Data System (ADS)

Blaen, Phillip; Kurz, Marie; Knapp, Julia; Mendoza-Lera, Clara; Lee-Cullin, Joe; Klaar, Megan; Drummond, Jen; Jaeger, Anna; Zarnetske, Jay; Lewandowski, Joerg; Marti, Eugenia; Ward, Adam; Fleckenstein, Jan; Datry, Thibault; Larned, Scott; Krause, Stefan

2016-04-01

Nutrient concentrations in surface waters and groundwaters are increasing in many agricultural catchments worldwide as a result of anthropogenic activities. Increasing geomorphological heterogeneity in river channels may help to attenuate nutrient pollution by facilitating water exchange fluxes with the hyporheic zone; a site of intense microbial activity where biogeochemical transformation rates (e.g. denitrification) can be high. However, the controls on spatial variability in biogeochemical cycling, particularly at scales relevant for river managers, are not well understood. Here, we aimed to assess: 1) how differences in geomorphological heterogeneity control river solute transport and rates of biogeochemical cycling at sub-reach scales (102 m); and 2) the relative magnitude of these differences versus those relating to reach scale substrate variability (103 m). We used the reactive 'smart' tracer resazurin (Raz), a weakly fluorescent dye that transforms to highly fluorescent resorufin (Rru) under mildly reducing conditions, as a proxy to assess rates of biogeochemical cycling in a lowland river in southern England. Solute tracer tests were conducted in two reaches with contrasting substrates: one sand-dominated and the other gravel-dominated. Each reach was divided into sub-reaches that varied in geomorphic complexity (e.g. by the presence of pool-riffle sequences or the abundance of large woody debris). Slug injections of Raz and the conservative tracer fluorescein were conducted in each reach during baseflow conditions (Q ≈ 80 L/s) and breakthrough curves monitored using in-situ fluorometers. Preliminary results indicate overall Raz:Rru transformation rates in the gravel-dominated reach were more than 50% higher than those in the sand-dominated reach. However, high sub-reach variability in Raz:Rru transformation rates and conservative solute transport parameters suggests small-scale targeted management interventions to alter geomorphic heterogeneity may be

The complete mitochondrial genome of eastern lowland gorilla, Gorilla beringei graueri, and comparative mitochondrial genomics of Gorilla species.

PubMed

Hu, Xiao-di; Gao, Li-zhi

2016-01-01

In this study, we determined the complete mitochondrial (mt) genome of eastern lowland gorilla, Gorilla beringei graueri for the first time. The total genome was 16,416 bp in length. It contained a total of 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and 1 control region (D-loop region). The base composition was A (30.88%), G (13.10%), C (30.89%) and T (25.13%), indicating that the percentage of A+T (56.01%) was higher than G+C (43.99%). Comparisons with the other publicly available Gorilla mitogenome showed the conservation of gene order and base compositions but a bunch of nucleotide diversity. This complete mitochondrial genome sequence will provide valuable genetic information for further studies on conservation genetics of eastern lowland gorilla.

Downstream change in leucine aminopeptidase activity and leucine assimilation by epilithic microbiota along the River Swale, northern England.

PubMed

Ainsworth, A M; Goulder, R

2000-05-05

Parallel determinations of epilithic extracellular leucine aminopeptidase activity and leucine assimilation were made at five sites along 112 km of the River Swale and also in two tributaries, the River Wiske and Cod Beck. Epilithic leucine aminopeptidase activity along the Swale increased with distance downstream; this increase was gradual, rather than stepwise in response to specific sewage-works outfalls. Epilithic leucine assimilation, in contrast, did not consistently increase along the river. Epilithic leucine aminopeptidase activity and leucine assimilation were both potentially controlled by epilithic microbial variables (bacterial abundance and chlorophyll a) while leucine aminopeptidase activity was also strongly related to water-quality variables, especially temperature, pH and conductivity. Epilithic leucine aminopeptidase activity and leucine assimilation were coupled, but the magnitude of aminopeptidase activity was always substantially greater than that of leucine assimilation. Arguments are presented, however, which suggest that this did not necessarily indicate the constant availability of excess leucine, and by inference amino-acid nitrogen, to epilithic bacteria. Values of epilithic leucine aminopeptidase activity and leucine assimilation, expressed relative to rates in overlying water, suggested that most activity and assimilation was epilithic rather than planktonic, although the planktonic contribution was proportionately greater at the deeper, more downstream, sites. In the tributaries, River Wiske and Cod Beck, values of epilithic leucine aminopeptidase activity and epilithic microbial abundance, as well as those of many water-quality variables, resembled values in the middle and lower Swale. Thus, these tributaries were essentially lowland, enriched watercourses being very different from the headstreams of the main river.

Post-project appraisals in adaptive management of river channel restoration.

PubMed

Downs, Peter W; Kondolf, G Mathias

2002-04-01

Post-project appraisals (PPAs) can evaluate river restoration schemes in relation to their compliance with design, their short-term performance attainment, and their longer-term geomorphological compatibility with the catchment hydrology and sediment transport processes. PPAs provide the basis for communicating the results of one restoration scheme to another, thereby improving future restoration designs. They also supply essential performance feedback needed for adaptive management, in which management actions are treated as experiments. PPAs allow river restoration success to be defined both in terms of the scheme attaining its performance objectives and in providing a significant learning experience. Different levels of investment in PPA, in terms of pre-project data and follow-up information, bring with them different degrees of understanding and tbus different abilities to gauge both types of success. We present four case studies to illustrate how the commitment to PPA has determined the understanding achieved in each case. In Moore's Gulch (California, USA), understanding was severely constrained by the lack of pre-project data and post-implementation monitoring. Pre-project data existed for the Kitswell Brook (Hertfordshire, UK), but the monitoring consisted only of one site visit and thus the understanding achieved is related primarily to design compliance issues. The monitoring undertaken for Deep Run (Maryland, USA) and the River Idle (Nottinghamshire, UK) enabled some understanding of the short-term performance of each scheme. The transferable understanding gained from each case study is used to develop an illustrative five-fold classification of geomorphological PPAs (full, medium-term, short-term, one-shot, and remains) according to their potential as learning experiences. The learning experience is central to adaptive management but rarely articulated in the literature. Here, we gauge the potential via superimposition onto a previous schematic

Interaction of surface water and groundwater in the Nile River basin: isotopic and piezometric evidence

NASA Astrophysics Data System (ADS)

Kebede, Seifu; Abdalla, Osman; Sefelnasr, Ahmed; Tindimugaya, Callist; Mustafa, Osman

2017-05-01

Past discussions around water-resources management and development in the River Nile basin disregard groundwater resources from the equation. There is an increasing interest around factoring the groundwater resources as an integral part of the Nile Basin water resources. This is hampered by knowledge gap regarding the groundwater resources dynamics (recharge, storage, flow, quality, surface-water/groundwater interaction) at basin scale. This report provides a comprehensive analysis of the state of surface-water/groundwater interaction from the headwater to the Nile Delta region. Piezometric and isotopic (δ18O, δ2H) evidence reveal that the Nile changes from a gaining stream in the headwater regions to mostly a loosing stream in the arid lowlands of Sudan and Egypt. Specific zones of Nile water leakage to the adjacent aquifers is mapped using the two sources of evidence. Up to 50% of the surface-water flow in the equatorial region of the Nile comes from groundwater as base flow. The evidence also shows that the natural direction and rate of surface-water/groundwater interaction is largely perturbed by human activities (diversion, dam construction) particularly downstream of the Aswan High Dam in Egypt. The decrease in discharge of the Nile River along its course is attributed to leakage to the aquifers as well as to evaporative water loss from the river channel. The surface-water/groundwater interaction occurring along the Nile River and its sensitivity to infrastructure development calls for management strategies that account groundwater as an integral part of the Nile Basin resources.

Late Hesperian plains formation and degradation in a low sedimentation zone of the northern lowlands of Mars

USGS Publications Warehouse

Rodriguez, J.A.P.; Tanaka, K.L.; Berman, D.C.; Kargel, J.S.

2010-01-01

The plains materials that form the martian northern lowlands suggest large-scale sedimentation in this part of the planet. The general view is that these sedimentary materials were transported from zones of highland erosion via outflow channels and other fluvial systems. The study region, the northern circum-polar plains south of Gemini Scopuli on Planum Boreum, comprises the only extensive zone in the martian northern lowlands that does not include sub-basin floors nor is downstream from outflow channel systems. Therefore, within this zone, the ponding of fluids and fluidized sediments associated with outflow channel discharges is less likely to have taken place relative to sub-basin areas that form the other northern circum-polar plains surrounding Planum Boreum. Our findings indicate that during the Late Hesperian sedimentary deposits produced by the erosion of an ancient cratered landscape, as well as via sedimentary volcanism, were regionally emplaced to form extensive plains materials within the study region. The distribution and magnitude of surface degradation suggest that groundwater emergence from an aquifer that extended from the Arabia Terra cratered highlands to the northern lowlands took place non-catastrophically and regionally within the study region through faulted upper crustal materials. In our model the margin of the Utopia basin adjacent to the study region may have acted as a boundary to this aquifer. Partial destruction and dehydration of these Late Hesperian plains, perhaps induced by high thermal anomalies resulting from the low thermal conductivity of these materials, led to the formation of extensive knobby fields and pedestal craters. During the Early Amazonian, the rates of regional resurfacing within the study region decreased significantly; perhaps because the knobby ridges forming the eroded impact crater rims and contractional ridges consisted of thermally conductive indurated materials, thereby inducing freezing of the tectonically

Stock, turnover and functions of carbon in heavily weathered soils under lowland rainforest transformation systems

NASA Astrophysics Data System (ADS)

Guillaume, Thomas; Kuzyakov, Yakov

2013-04-01

Tropical rainforest are experiencing worldwide a strong lost through deforestation and transformation into agricultural systems. Land use changes in such ecosystems leads to major modifications of soils properties and processes. One indication of it are the losses of organic carbon content (Corg); an important soil fertility parameter in heavily weathered soil. Between 1985 and 2007, Sumatra (Indonesia) has lost half of his remaining natural rainforest, which currently covers only 30% the island. The deforestation is still ongoing and the main drivers of deforestation are oil palm, rubber and timber industries. Our study aims to identify and quantify the impacts of lowland rainforest transformation systems (TS): oil palm, rubber and jungle rubber plantations on soil organic carbon (SOC) and nitrogen (SON) quality, turnover and stocks and so, on soil fertility and functions. We hypothesize that transformation of natural lowland rainforest changes not only C stock and budget throughout quantity and quality of C input, but also DOM production and water consumption by vegetation, leading to a relocation of C in the subsoil. This should be reflected in C and N content in soil profile horizons as well as their δ13C and δ15N isotopic signatures. We will evaluate also C stability through biological, thermal and chemical stability in bulk soil and aggregate fractions. The TS investigated, including lowland rainforest as reference sites, are located in Jambi Province (Sumatra). Soil has been described and sampled per horizon on 4 replicates of each TS in 2 different regions (32 sites) in Autumn 2012. As hypothesized, first results show strong effects of forest transformation on C and N content, as well as on isotopic signatures of soil. Those results will also be used further to select DOM sampling depths and adequate horizons to perform sorption and incubation experiments.

The Effects of a Changing Climate and Urbanisation on River Flows in the Thames Basin, UK - a Hydrological Modelling Approach

NASA Astrophysics Data System (ADS)

Miller, J. D.; Rickards, N. J.; Kjeldsen, T. R.; Hutchins, M.; Rowland, C.; Prudhomme, C.; Maliko, T.; Fidal, J.; Hagen-Zanker, A.

2016-12-01

The UK population is set to increase by 16% by 2035; it is therefore increasingly important to understand the impact this may have on urban populations, and in turn how this will affect river flow regimes and water quality in urban areas. A growing population is likely to lead to an increase in urban land use and impervious surfaces, the implications of which are not yet fully understood for issues such as future flood risk. The aim of this paper is to develop a greater understanding of the impacts of both an increasing population and urban extent in the context of a changing climate, and to assess the effect these may have on urban streamflow regimes and water security in the future. Flows are modelled for selected catchments in the Thames basin using URBMOD, a lumped rainfall runoff model that is able to represent both pervious and impervious surfaces, reducing infiltration in catchments where there is a greater urban extent. The model uses daily catchment average rainfall and evapotranspiration derived from gridded data, and is calibrated against long-term river flow records. Historic satellite imagery is used to train cellular automata land use models, which are then applied under different scenarios of urban development up to 2035. These changes in land use are combined with a range of climate change scenarios to give an indication of how urban flow regimes may be altered in the Thames basin over the next 20 years. Results suggest an intensification of the hydrological regime in the majority of catchments, with increases in high flow magnitudes (Q10) of up to 5%. The trend for low flows (Q90) is less clear, with some catchments displaying reductions of around 4%, whilst others show slight increased flows. We identify the main drivers behind these changes, from which the fine-scale impacts of urbanisation on water resources can be better understood. Research findings are being used to inform a regional-scale model, coupling water quantity and quality and

Morphological and molecular characterization and phylogenetic relationships of a new species of trypanosome in Tapirus terrestris (lowland tapir), Trypanosoma terrestris sp. nov., from Atlantic Rainforest of southeastern Brazi.

PubMed

Acosta, Igor da Cunha Lima; da Costa, Andrea Pereira; Nunes, Pablo Henrique; Gondim, Maria Fernanda Naegeli; Gatti, Andressa; Rossi, João Luiz; Gennari, Solange Maria; Marcili, Arlei

2013-12-11

The Lowland tapir (Tapirus terrestris) is the largest Brazilian mammal and despite being distributed in various Brazilian biomes, it is seriously endangered in the Atlantic Rainforest. These hosts were never evaluated for the presence of Trypanosoma parasites. The Lowland tapirs were captured in the Brazilian southeastern Atlantic Rainforest, Espírito Santo state. Trypanosomes were isolated by hemoculture, and the molecular phylogeny based on small subunit rDNA (SSU rDNA) and glycosomal-3-phosphate dehydrogenase (gGAPDH) gene sequences and the ultrastructural features seen via light microscopy and scanning and transmission electron microscopy are described. Phylogenetic trees using combined SSU rDNA and gGAPDH data sets clustered the trypanosomes of Lowland tapirs, which were highly divergent from other trypanosome species. The phylogenetic position and morphological discontinuities, mainly in epimastigote culture forms, made it possible to classify the trypanosomes from Lowland tapirs as a separate species. The isolated trypanosomes from Tapirus terrestris are a new species, Trypanosoma terrestris sp. n., and were positioned in a new Trypanosoma clade, named T. terrestris clade.

Morphological and molecular characterization and phylogenetic relationships of a new species of trypanosome in Tapirus terrestris (lowland tapir), Trypanosoma terrestris sp. nov., from Atlantic Rainforest of southeastern Brazi

PubMed Central

2013-01-01

Background The Lowland tapir (Tapirus terrestris) is the largest Brazilian mammal and despite being distributed in various Brazilian biomes, it is seriously endangered in the Atlantic Rainforest. These hosts were never evaluated for the presence of Trypanosoma parasites. Methods The Lowland tapirs were captured in the Brazilian southeastern Atlantic Rainforest, Espírito Santo state. Trypanosomes were isolated by hemoculture, and the molecular phylogeny based on small subunit rDNA (SSU rDNA) and glycosomal-3-phosphate dehydrogenase (gGAPDH) gene sequences and the ultrastructural features seen via light microscopy and scanning and transmission electron microscopy are described. Results Phylogenetic trees using combined SSU rDNA and gGAPDH data sets clustered the trypanosomes of Lowland tapirs, which were highly divergent from other trypanosome species. The phylogenetic position and morphological discontinuities, mainly in epimastigote culture forms, made it possible to classify the trypanosomes from Lowland tapirs as a separate species. Conclusions The isolated trypanosomes from Tapirus terrestris are a new species, Trypanosoma terrestris sp. n., and were positioned in a new Trypanosoma clade, named T. terrestris clade. PMID:24330660

River Ecosystem Response to Prescribed Vegetation Burning on Blanket peatland

PubMed Central

Brown, Lee E.; Johnston, Kerrylyn; Palmer, Sheila M.; Aspray, Katie L.; Holden, Joseph

2013-01-01

Catchment-scale land-use change is recognised as a major threat to aquatic biodiversity and ecosystem functioning globally. In the UK uplands rotational vegetation burning is practised widely to boost production of recreational game birds, and while some recent studies have suggested burning can alter river water quality there has been minimal attention paid to effects on aquatic biota. We studied ten rivers across the north of England between March 2010 and October 2011, five of which drained burned catchments and five from unburned catchments. There were significant effects of burning, season and their interaction on river macroinvertebrate communities, with rivers draining burned catchments having significantly lower taxonomic richness and Simpson’s diversity. ANOSIM revealed a significant effect of burning on macroinvertebrate community composition, with typically reduced Ephemeroptera abundance and diversity and greater abundance of Chironomidae and Nemouridae. Grazer and collector-gatherer feeding groups were also significantly less abundant in rivers draining burned catchments. These biotic changes were associated with lower pH and higher Si, Mn, Fe and Al in burned systems. Vegetation burning on peatland therefore has effects beyond the terrestrial part of the system where the management intervention is being practiced. Similar responses of river macroinvertebrate communities have been observed in peatlands disturbed by forestry activity across northern Europe. Finally we found river ecosystem changes similar to those observed in studies of wild and prescribed forest fires across North America and South Africa, illustrating some potentially generic effects of fire on aquatic ecosystems. PMID:24278367

Modelling metaldehyde in catchments: a River Thames case-study.

PubMed

Lu, Q; Whitehead, P G; Bussi, G; Futter, M N; Nizzetto, L

2017-04-19

The application of metaldehyde to agricultural catchment areas to control slugs and snails has caused severe problems for drinking water supply in recent years. In the River Thames catchment, metaldehyde has been detected at levels well above the EU and UK drinking water standards of 0.1 μg l -1 at many sites across the catchment between 2008 and 2015. Metaldehyde is applied in autumn and winter, leading to its increased concentrations in surface waters. It is shown that a process-based hydro-biogeochemical transport model (INCA-contaminants) can be used to simulate metaldehyde transport in catchments from areas of application to the aquatic environment. Simulations indicate that high concentrations in the river system are a direct consequence of excessive application rates. A simple application control strategy for metaldehyde in the Thames catchment based on model results is presented.

The Demonstration Test Catchment Approach to Land and Water Management in the river Eden Watershed, UK. (Invited)

NASA Astrophysics Data System (ADS)

Jonczyk, J.; Quinn, P. F.; Haygarth, P.; Reaney, S.; Wilkinson, M.; Burke, S.; McGonigle, D.; Harris, B.

2010-12-01

The Demonstration Test Catchment (DTC) initiative is a five year project to address pollution issues in catchments. The initiative will study the wider environmental problems suffered by catchments which are under intense farming pressures and potential climate change impacts. The UK Department for Food, Agriculture and Rural Affairs (Defra) in partnership with the Environment Agency for England and Wales (EA) have funded this initiative to answer key policy concerns in catchments. The first key step has been the establishment of a ‘research platform’ at three catchments in the UK (The Eden, Wensum and Hampshire Avon) whereby funding of 9.3 million dollars has gone into funding new equipment and pollution sampling regimes have been established. Within each catchment between three and four, 8-10km2 sub-catchments have been established. The experimental design and thinking for DTCs will be explained fully in this paper. The next phase of the project will install an extensive suite of land management and pollution mitigation interventions. In parallel to this monitoring work, a full knowledge exchange package will seek to engage with farmers, the rural community and understand the governance regime at the broader catchment scale. There is also a need for a modelling component to upscale the findings to the whole of the UK. Whilst this is an ambitious goal, there is a very basic commitment of working with rural communities to come up with real solutions that will help underpin effective policy making for the future. The research platform covers a multi-scale approach to the monitoring strategy that will allow local grouping of mitigation measures to be studied local in terms of impact and propagated to the catchment scale. Even with high level of funding, the DTC can only fully instrument a catchment of 8-10km2. Beyond this scale, the EA and the standard catchment monitoring will continue as normal. The focus here is to prove that mitigation can be achieved within

Connecting the Yakima fold and thrust belt to active faults in the Puget Lowland, Washington

USGS Publications Warehouse

Blakely, R.J.; Sherrod, B.L.; Weaver, C.S.; Wells, R.E.; Rohay, A.C.; Barnett, E.A.; Knepprath, N.E.

2011-01-01

High-resolution aeromagnetic surveys of the Cascade Range and Yakima fold and thrust belt (YFTB), Washington, provide insights on tectonic connections between forearc and back-arc regions of the Cascadia convergent margin. Magnetic surveys were measured at a nominal altitude of 250 m above terrain and along flight lines spaced 400 m apart. Upper crustal rocks in this region have diverse magnetic properties, ranging from highly magnetic rocks of the Miocene Columbia River Basalt Group to weakly magnetic sedimentary rocks of various ages. These distinctive magnetic properties permit mapping of important faults and folds from exposures to covered areas. Magnetic lineaments correspond with mapped Quaternary faults and with scarps identified in lidar (light detection and ranging) topographic data and aerial photography. A two-dimensional model of the northwest striking Umtanum Ridge fault zone, based on magnetic and gravity data and constrained by geologic mapping and three deep wells, suggests that thrust faults extend through the Tertiary section and into underlying pre-Tertiary basement. Excavation of two trenches across a prominent scarp at the base of Umtanum Ridge uncovered evidence for bending moment faulting possibly caused by a blind thrust. Using aeromagnetic, gravity, and paleoseismic evidence, we postulate possible tectonic connections between the YFTB in eastern Washington and active faults of the Puget Lowland. We suggest that faults and folds of Umtanum Ridge extend northwestward through the Cascade Range and merge with the Southern Whidbey Island and Seattle faults near Snoqualmie Pass 35 km east of Seattle. Recent earthquakes (MW ≤ 5.3) suggest that this confluence of faults may be seismically active today.

Development of sedentary communities in the Maya lowlands: Coexisting mobile groups and public ceremonies at Ceibal, Guatemala

PubMed Central

Inomata, Takeshi; MacLellan, Jessica; Triadan, Daniela; Munson, Jessica; Burham, Melissa; Aoyama, Kazuo; Nasu, Hiroo; Pinzón, Flory; Yonenobu, Hitoshi

2015-01-01

Our archaeological investigations at Ceibal, a lowland Maya site located in the Pasión region, documented that a formal ceremonial complex was built around 950 B.C. at the onset of the Middle Preclassic period, when ceramics began to be used in the Maya lowlands. Our refined chronology allowed us to trace the subsequent social changes in a resolution that had not been possible before. Many residents of Ceibal appear to have remained relatively mobile during the following centuries, living in ephemeral post-in-ground structures and frequently changing their residential localities. In other parts of the Pasión region, there may have existed more mobile populations who maintained the traditional lifestyle of the preceramic period. Although the emerging elite of Ceibal began to live in a substantial residential complex by 700 B.C., advanced sedentism with durable residences rebuilt in the same locations and burials placed under house floors was not adopted in most residential areas until 500 B.C., and did not become common until 300 B.C. or the Late Preclassic period. During the Middle Preclassic period, substantial formal ceremonial complexes appear to have been built only at a small number of important communities in the Maya lowlands, and groups with different levels of sedentism probably gathered for their constructions and for public rituals held in them. These collaborative activities likely played a central role in socially integrating diverse groups with different lifestyles and, eventually, in developing fully established sedentary communities. PMID:25831523

Contribution of bank erosion to the sediment budget of a drained agricultural lowland catchment

NASA Astrophysics Data System (ADS)

Cerdan, Olivier; Foucher, Anthony; Vandromme, Rosalie; Salvador-Blanes, Sébastien; Gay, Aurore; Landemaine, Valentin; Evrard, Olivier