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1

Recharge sources and hydrogeochemical evolution of groundwater in alluvial basins in arid central Australia  

NASA Astrophysics Data System (ADS)

SummaryIt is necessary to define the role of various sources of recharge in the surficial alluvial aquifer system in arid Alice Springs in central Australia, for future management of water resources in the region. Multiple sources of natural recharge include infiltration from ephemeral stream flow in the Todd River; groundwater throughflow between connected alluvial basins; regional groundwater flow from the underlying Tertiary aquifer; and diffuse recharge. In addition treatment, storage and irrigation reuse of Alice Springs' waste water has resulted in additional recharge of effluent, via infiltration. Water resource management plans for the region include effluent reuse through Soil Aquifer Treatment (SAT) within one of the connected alluvial basins, with the purpose of managing the excess waste water overflows while also supplementing groundwater resources for irrigation and protecting their quality. Hydrogeochemical tracers, chloride and the stable isotopes of water, were used in a three-member mixing model to define and quantify the major recharge sources. The mixing model was not sensitive enough to quantify minor contributions from effluent in groundwater that were identified only by an evaporated isotopic signature. The contribution of the multiple recharge sources varied spatially with proximity to the recharge source; with Todd River, effluent and Town Basin throughflow contributing to the Inner Farm Basin groundwater. The Outer Farm Basin was largely influenced by the Todd River, the Inner Farm Basin throughflow and the older Tertiary aquifer. While Inner Farm groundwater throughflow contains an effluent component, only Outer Farm Basin groundwater near the interface between the two basins clearly illustrated an effluent signature. Aside from this, effluent recharge was not evident in the Outer Farm Basin, indicating that past unmanaged recharge practices will not mask signs of Managed Aquifer Recharge through the Soil Aquifer Treatment (SAT) operation. The long-term impact of effluent recharge is a shift from sodium and calcium as co-dominant cations in the groundwater, as evident in the Outer Farm Basin, to dominance by sodium alone, as typical for the Inner Farm Basin.

Vanderzalm, J. L.; Jeuken, B. M.; Wischusen, J. D. H.; Pavelic, P.; Le Gal La Salle, C.; Knapton, A.; Dillon, P. J.

2011-01-01

2

Impacts of urbanization on groundwater quality and recharge in a semi-arid alluvial basin  

NASA Astrophysics Data System (ADS)

SummaryThe management of groundwater resources is paramount in semi-arid regions experiencing urban development. In the southwestern United States, enhancing recharge of urban storm runoff has been identified as a strategy for augmenting groundwater resources. An understanding of how urbanization may impact the timing of groundwater recharge and its quality is a prerequisite for mitigating water scarcity and identifying vulnerability to contamination. We sampled groundwater wells along the Rillito Creek in southern Arizona that had been previously analyzed for tritium in the late 1980s to early 1990s and analyzed samples for tritium ( 3H) and helium-3 ( 3H/ 3He) to evaluate changes in 3H and age date groundwaters. Groundwater samples were also analyzed for chlorofluorocarbons (CFCs) and basic water quality metrics. Substantial changes in 3H values from waters sampled in the early 1990s compared to 2009 were identified after accounting for radioactive decay and indicate areas of rapid recharge. 3H- 3He groundwater ages ranged from 22 years before 2009 to modern recharge. CFC-11, -12 and -113 concentrations were anomalously high across the basin, and non-point source pollution in runoff and/or leaky infrastructure was identified as the most plausible source of this contamination. CFCs were strongly and positively correlated to nitrate ( r2 = 0.77) and a mobile trace metal, nickel ( r2 = 0.71), suggesting that solutes were derived from a similar source. Findings from this study suggest new waters from urban non-point sources are contributing to groundwater recharge and adversely affecting water quality. Reducing delivery of contaminants to areas of focused recharge will be critical to protect future groundwater resources.

Carlson, Mark A.; Lohse, Kathleen A.; McIntosh, Jennifer C.; McLain, Jean E. T.

2011-10-01

3

Predicting changes in hydrologic retention in an evolving semi-arid alluvial stream  

Microsoft Academic Search

Hydrologic retention of solutes in hyporheic zones or other slowly moving waters of natural channels is thought to be a significant control on biogeochemical cycling and ecology of streams. To learn more about factors affecting hydrologic retention, we repeated stream-tracer injections for 5 years in a semi-arid alluvial stream (Pinal Creek, Ariz.) during a period when streamflow was decreasing, channel

Judson W. Harvey; Martha H. Conklin; Roger S. Koelsch

2003-01-01

4

Water Balance within Intensively Cultivated Alluvial Plain in an Arid Environment  

Microsoft Academic Search

The Tuoshigan–Kumalake River alluvial plain is an oasis located in the Tarim River Basin of Xinjiang, China. Large water consumption\\u000a reduces the discharge and jeopardizes the ecosystem of the lower reaches of the Tarim River. Therefore a recent regulation\\u000a is enacted to limit water use in the plain. The objective of this paper is to investigate the hydrological cycle inside

Qiuhong Tang; Heping Hu; Taikan Oki; Fuqiang Tian

2007-01-01

5

Late Quaternary landscape evolution in the Kunlun Mountains and Qaidam Basin, Northern Tibet: A framework for examining the links between glaciation, lake level changes and alluvial fan formation  

USGS Publications Warehouse

The Qaidam Basin in Northern Tibet is one of the largest hyper-arid intermontane basins on Earth. Alluvial fans, pediment surfaces, shorelines and a thick succession of sediments within the basin, coupled with moraines and associated landforms in the adjacent high mountain catchments of the Kunlun Mountains, record a complex history of Late Quaternary paleoenvironmental change and landscape evolution. The region provides an ideal natural laboratory to examine the interaction between tectonics and climate within a continent-continent collision zone, and to quantify rates of landscape evolution as controlled by climate and the associated glacial and hydrological changes in hyper-arid and adjacent high-altitude environments. Geomorphic mapping, analysis of landforms and sediments, and terrestrial cosmogenic radionuclide surface exposure and optically stimulated luminescence dating serve to define the timing of formation of Late Quaternary landforms along the southern and northwestern margins of the Qaidam Basin, and in the Burhan Budai Shan of the Kunlun Mountains adjacent to the basin on the south. These dates provide a framework that suggests links between climatic amelioration, deglaciation, lake desiccation and alluvial fan evolution. At least three glacial advances are defined in the Burham Budai Shan of the Kunlun Mountains. On the northern side of this range these occurred in the penultimate glacial cycle or early in the last glacial cycle, during the Last Glacial Maximum (LGM)/Lateglacial and during the Holocene. On the south side of the range, advances occurred during the penultimate glacial cycle, MIS-3, and possibly the LGM, Lateglacial or Holocene. Several distinct phases of alluvial fan sedimentation are likewise defined. Alluvial fans formed on the southern side of the Kunlun Mountains prior to 200 ka. Ice-contact alluvial fans formed during the penultimate glacial and during MIS-3. Extensive incised alluvial fans that form the main valley fills north of the Burham Budai and extend into the Qaidam Basin are dated to ???30 ka. These ages suggest that there was a period of alluvial fan aggradation and valley filling that persisted until desiccation of the large lakes in the Qaidam Basin post ???30 ka led to base level lowering and active incision of streams into the valley fills. The continued Lateglacial and Holocene desiccation likely led to further degradation of the valley fills. Ice wedge casts in the Qaidam Basin date to ???15 ka, indicating significant Lateglacial climatic amelioration, while Holocene loess deposits north of the Burham Bdudai suggest that aridity has increased in the region since the early Holocene. From these observations, we infer that the major landscape changes within high glaciated mountains and their adjacent hyper-arid intermontane basins, such as the Kunlun Mountains and Qaidam Basin, occur rapidly over millennial timescales during periods of climatic instability. ?? 2006 Elsevier Ltd and INQUA.

Owen, L.A.; Finkel, R.C.; Haizhou, M.; Barnard, P.L.

2006-01-01

6

Variation in sedimentology and architecture of Eocene alluvial strata, Wind River and Washakie basins, Wyoming  

SciTech Connect

Eocene continental, alluvial strata of the Wind River Formation (Wind River Basin) and the Cathedral Bluffs Member of the Wasatch Formation (Washakie basin) provide two examples of Laramide intermontane basin aggradation. These alluvial sediments primarily represent overbank flood deposits marginal to channel complexes. Their sedimentology and architecture, although grossly similar, appear to vary somewhat with proximity to Laramide uplifts. In both cases, repetitive sedimentation on the floodplain produced a succession of depositional couplets, each composed of a light-gray sand overlain by a red clay-rich silt or sand. The lower sands are tabular bodies that, near their distal margins, taper discernibly. They commonly display planar and ripple-drift laminations. Upper clay-rich layers, which are laminated, are also generally tabular. Those floodplain strata depositional proximal to Laramide uplifts show little evidence of scouring prior to deposition of the next, overlying couplet. Most of these sedimentary layers, therefore, are laterally continuous (up to 2 km). This alluvial architecture results in relatively uniform porosity laterally within depositional units but variable porosity stratigraphically through the sequence. In contrast, alluvial sediments deposited farther from the Laramide uplifts have undergone sporadic incision (either during rising flood stage or subsequently) followed by aggradation. As a result, many of these floodplain couplets are discontinuous laterally and, hence, exhibit large-scale lateral variability in porosity. Both alluvial sequences have undergone similar types and extents of burial diagenesis.

Patterson, P.E.; Larson, E.E. (Univ. of Colorado, Boulder (United States))

1991-03-01

7

Ground-water data from selected wells in alluvial aquifers, Powder River basin, northeastern Wyoming  

USGS Publications Warehouse

Data on selected wells completed in alluvial aquifers in the Powder River structural basin in northeastern Wyoming are presented without interpretation. Records of 300 wells, chemical analyses of water from 43 wells, and logs of 113 wells are listed in three tables. A map showing location of wells is included. (USGS)

Wells, Deborah K.

1982-01-01

8

Ground-water quality in alluvial basins that have minimal urban development, south-central Arizona  

USGS Publications Warehouse

Ground-water quality data (1917-96) from 772 wells in 16 alluvial basins that have minimal urban development were used to determine the effect of nonurban factors on ground-water quality in south- central Arizona. Characterization of the spatial variability of ground-water quality within and among alluvial basins that have minimal urban development will provide a baseline to which water- quality problems associated with urbanization can be compared. Four water-type categories--calcium carbonate, calcium mixed anion, sodium carbonate, and sodium chloride--were used to classify the 13 alluvial basins for which adequate data were available. Ground-water quality was compared to U.S. Environmental Protaection Agency maximum contaminant levels for drinking water, depth of well, and depth to top of perforated interval for five alluvial basins that represented the four water-type categories. Exceedances of maximum contaminant levels for fluoride and nitrate occurred in three and four basins, respectively, of the five selected basins. Specific-conductance values for ground water in the five selected basins tend to increase in a northwesterly direction toward the central part of Arizona as the extent of evaporite deposits increases. The results of this study, which are part of the U.S. Geological Survey's National Water-Quality Assessment Program, can be used to determine the effects of urban land-use activities on ground-water quality in similar hydrogeologic conditions and may be the best indicator available for nonurban ground-water quality in the region.

Gellenbeck, Dorinda J.; Coes, Alissa L.

1999-01-01

9

Holocene climate change in arid Australia from speleothem and alluvial records  

Microsoft Academic Search

New high-resolution MC-ICPMS U\\/Th ages and C and O isotopic analyses from a Holocene speleothem in arid south-central Australia provide evidence for increased effective precipitation (EP) relative to present at c. 11.5 ka and c. 8—5 ka, peak moisture at 7—6 ka, and onset of an arid climate similar to present by c. 5 ka. ?18O and ?13C time-series data

Mark C. Quigley; Travis Horton; John C. Hellstrom; Matthew L. Cupper; Mike Sandiford

2010-01-01

10

Extreme Flood-Driven Dynamics of a mixed bedrock-alluvial Influenced Semi-Arid River  

NASA Astrophysics Data System (ADS)

Many of the large rivers draining southern Africa are characterised by incised bedrock ';macrochannels' cut 10-20 m into ancient planation surfaces but with variable amounts of unconsolidated sediment infill. Variations in lithology, structure, flow regime, sediment supply, and vegetation assemblages have created morphologically diverse river systems, many of which have been characterised by extended periods of alluviation on an historic timescale, thereby leading to the development of an increasingly alluviated set of channel types that commonly mask the underlying bedrock. However, cyclone-driven extreme flows are known to cause extensive erosion along these systems and may exert the primary control over their morphologic development. This paper reports on two significant cyclone events (2000 and 2012) that have impacted on the rivers of the Kruger National Park, with floods on the Sabie and Olifants estimated as among the largest documented Holocene floods for any South African river. Prior to the floods, both rivers displayed a diverse but well-ordered set of channel types (e.g. braided, anastomosed), with considerable lengths of both systems exhibiting fully alluvial conditions. Evaluation of post-flood aerial imagery has shown that the extreme flows have stripped this sediment, exposing and eroding the underlying weathered bedrock, particularly along the Olifants. This response suggests that although alluviation occurs over short timescales, the systems remain highly susceptible to alluvial and bedrock erosion during extreme floods. This is demonstrated by the results of a 2D hydraulic modelling study of the rivers. Simulation of the peak flood flow conditions shows that extreme shear stresses capable of eroding cohesive, well-vegetated sediments were predicted extensively within the macrochannels. Where remnant deposits remained from the 2000 floods, these areas were seen to be particularly vulnerable to erosion in the 2012 floods, due principally to their increased exposure to fluid forces. The ephemeral nature of the sediment infill is also supported by OSL dating, with preliminary ages from remnant bars, islands and floodplains suggesting that no deposits older than around 500 years can be found along the rivers. Together, the results imply that although periods of extensive alluviation may have been witnessed historically, on a longer (late Quaternary) timescale the alluvial morphologies are frequently reworked, with the geological setting and extreme climatic influence creating conditions conducive to the continuing erosion and development of the bedrock macrochannel template.

Entwistle, N. S.; Heritage, G. L.; Tooth, S.; Milan, D. J.

2013-12-01

11

Estimating recharge distribution by incorporating runoff from mountainous areas in an alluvial basin in the Great Basin region of the southwestern United States.  

PubMed

A method is described to estimate the distribution of ground water recharge within hydrographic basins in the Great Basin region of the southwestern United States on the basis of estimated runoff from high mountainous areas and subsequent infiltration in alluvial fans surrounding the intermontane basins. The procedure involves a combination of Geographic Information System (GIS) analysis, empirical surface-runoff modeling, and water-balance calculations. The method addresses the need to develop and incorporate constraints on the distribution of recharge in regional-scale ground water flow modeling of arid and semiarid environments. The conceptual approach and methodology were developed for Crescent Valley, Nevada. However, the concept and method are generally applicable to any region where excess precipitation in upland areas is conveyed to lower elevations before it infiltrates to recharge the ground water system. Application of the procedure to a ground water flow model of Crescent Valley appears both qualitatively and quantitatively to result in a more accurate representation of actual recharge conditions than might otherwise have been prescribed. PMID:11708447

Stone, D B; Moomaw, C L; Davis, A

2001-01-01

12

Groundwater and Surface Water Interaction of Several Irrigation Systems in the Mississippi River Basin Alluvial Aquifer  

NASA Astrophysics Data System (ADS)

The Lower Mississippi River Basin alluvial aquifer provides irrigation water for agriculture in most of eastern Arkansas, western Tennessee, southeastern Missouri, western Mississippi and northeastern Louisiana. The alluvial aquifer depth to water has been declining by approximately 1 foot per year due to unsustainable pumping levels. Replacing groundwater with surface water sources in the Lower Mississippi River Basin is one of the many solutions to declining groundwater stores that has taken root in the region, especially in eastern Arkansas. Surface water irrigation systems consist of an on-farm reservoir and tailwater recovery. The reservoir is used to store water for later use during wet periods of the year and the tailwater recovery creates a closed basin of the irrigation system, allowing for use and re-use of irrigation water. Several irrigation systems were instrumented to further understand the interaction between surface water and groundwater in alluvial aquifer region. Three reservoirs, 9 streams and ditches, and 8 groundwater wells were instrumented in fall of 2011. Groundwater potentiometric surface under the storage reservoirs showed a rebound while a potentiometric surface falls sharply south and west moving away from the storage reservoirs. Preliminary results from the findings from these sites are presented.

Reba, M. L.; Rigby, J.; Czarnecki, J.; Rawlings, L.

2013-12-01

13

Variation of physical properties of alluvium in an arid basin  

NASA Astrophysics Data System (ADS)

We have used geologic and geophysical data from 139 drill holes in Yucca Flat, an alluvium-filled basin within the Nevada Test Site, to study the ways in which differing sources and transport processes of the alluvium are reflected in variations in physical parameters. Bulk density, grain density, pore water, and carbon dioxide are routinely measured in the subsurface alluvium for each drill hole, and porosity is calculated from the first three of these parameters. The alluvium is derived principally from three source rocks exposed along the perimeter of the basin: Plleozoic elastic and carbonate sedimentary rocks, and Tertiary volcanic tuff. The alluvium of Yucca Flat is subdivided into an older volcanic-rich basal tuffaceous alluvium and an overlying younger mixed alluvium; the latter is composed of both Paleozoic and Tertiary fragments, except near isolated source terranes, where it may be derived from only one of these rock types. The mixing of different sources where individual fans merge and coalesce at the center of the basin is reflected by progressive changes in the physical properties. Alluvium consisting of dominantly Paleozoic debritus has high density and relatively low water content and porosity, whereas alluvium composed of dominantly volcanic debris has low density and high porosity and water content. Mixing of these deposits near the center of the basin is reflected by intermediate densities. Water content and porosity are greatest at the center of the basin, where the alluvial sediments have undergone the greatest amount of distal fining and sorting.

Wagoner, Jeffrey L.; McKague, H. Lawrence

1986-04-01

14

Hydrogeochemical indicators of groundwater flow systems in the Yangwu River alluvial fan, Xinzhou Basin, Shanxi, China.  

PubMed

Based on analysis of groundwater hydrochemical and isotopic indicators, this article aims to identify the groundwater flow systems in the Yangwu River alluvial fan, in the Xinzhou Basin, China. Groundwater delta(2)H and delta(18)O values indicate that the origin of groundwater is mainly from precipitation, with local evaporative influence. d-excess values lower than 10% in most groundwaters suggest a cold climate during recharge in the area. Major ion chemistry, including rCa/rMg and rNa/rCl ratios, show that groundwater salinization is probably dominated by water-rock interaction (e.g., silicate mineral weathering, dissolution of calcite and dolomite and cation exchange) in the Yangwu River alluvial fan, and locally by intensive evapotranspiration in the Hutuo River valley. Cl and Sr concentrations follow an increasing trend in shallow groundwater affected by evaporation, and a decreasing trend in deep groundwater. (87)Sr/(86)Sr ratios reflect the variety of lithologies encountered during throughflow. The groundwater flow systems (GFS) of the Yangwu River alluvial fan include local and intermediate flow systems. Hydrogeochemical modeling results, simulated using PHREEQC, reveal water-rock interaction processes along different flow paths. This modeling method is more effective for characterizing flow paths in the intermediate system than in the local system. Artificial exploitation on groundwater in the alluvial fan enhances mixing between different groundwater flow systems. PMID:19548025

Han, Dongmei; Liang, Xing; Jin, Menggui; Currell, Matthew J; Han, Ying; Song, Xianfang

2009-08-01

15

Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill-Hole Data in Yucca Flat, Nye County, Nevada  

USGS Publications Warehouse

Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill-hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin such as alluvial fan, channel, basin axis, and playa deposits.

Sweetkind, Donald S.; Drake, Ronald M., II

2007-01-01

16

Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill Hole Data in Yucca Flat, Nye County, Nevada  

USGS Publications Warehouse

Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site (NTS) in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin including alluvial fan, channel, basin axis, and playa deposits.

Sweetkind, Donald S.; Drake, Ronald M., II

2007-01-01

17

Estimating the age of arid-zone alluvial fan surfaces using roughness measurements from spaceborne radar backscatter  

NASA Astrophysics Data System (ADS)

Alluvial fan surfaces respond to geologic and climate changes as they record the deposition and erosion processes that govern their evolution, which amongst others is manifested in the micro and meso scale topography of the surface. Remote sensing provides a regional view that is very useful for mapping. Some previous publications have demonstrated that relative dating can also be achieved by remote sensing using techniques common in planetary geology such as overlap relationships. This work focuses on the use of radar backscatter as suggested originally by Evans et al., (1992) to map ages but here we will try to provide an absolute geologic age. The objective of this paper is to demonstrate the use of radar backscatter to constrain surface roughness as a calibrated proxy for estimating age of alluvial surfaces. With the unique regional spatial perspective provided by spaceborne imaging, we aim at providing a new and complementary regional perspective for studying neotectonic and recent landscape evolution processes as well as paleoclimate. Moreover, the method (by radar backscattering measure) can be applied to the geomorphology of other planets. The current study is located in the southeastern part of the Negev desert, Israel on the late Pleistocene - Holocene Shehoret alluvial fan sequence. High resolution (0.5 cm) 3D roughness measurements were collected using a ground-based LIDAR (Leica HDS 3000) and these show a robust relationship between independently obtained OSL surface age and surface roughness; the fan surfaces become smoother with time over 103-105 yr timescales. Spaceborne backscatter radar data respond primarily to surface slope, roughness at a scale comparable to the radar wavelength, and other parameters such as dielectric properties of the surface. Therefore, radar can provide a good quantitative indication of surface roughness in arid zones, where vegetation cover is low. Preliminary results show a relationship between surface age and roughness and the radar cross section extracted from polarimetric spaceborne data. The best result is found in cross polarization (HV), L-band measured at an incidence angle of 38°.

Hetz, G.; Mushkin, A.; Blumberg, D. G.; Baer, G.; Trabelsky, E.

2012-12-01

18

Evaluation of groundwater recharge in Choushui River alluvial fan and Mingchu Basin for specific rainfall events  

NASA Astrophysics Data System (ADS)

Sound groundwater resources planning and management are lack in the Choushui River alluvial fan, resulting in the occurrence of serious land subsidence and seawater intrusion. Even the disasters induced by overpumping of groundwater pose a potential threat on the Taiwan High Speed Rail. In addition to improving the water resources management in the alluvial fan, the development of groundwater resources in the neighboring hills. Mingchu Basin, which is located on the midstream segment of the Choushui River and comprised of the gravel formation of Pleistocene, is an effective solution to resolve the problem in limited water resources. Moreover, the Dongpurui River and Qingshui River both converge into Choushui River in this basin. Because of wide drainage areas and good hydrogeological conditions, the Mingchu Basin is considered a high potential recharging region of groundwater. This work is to evaluate the groundwater recharge in the Choushui River alluvial fan and Mingchu Basin, using the WASH123D model equipped with the Groundwater Modeling System (GMS) to simulate the interaction of surface water and groundwater for specific five rainfall events. This study particularly focuses on the simulation of the groundwater flow, and evaluates the effect of different rainfall events on the groundwater recharge. First, to meet in-situ hydrogeological structure and hydraulic parameters, the GMS is used to construct hydrogeological database, mesh, hydrogeological parameters, initial condition and boundary conditions. Then, simulated parameters, such as hydraulic conductivity and pumping rates, need to be calibrated and verified in the model. After the calibration and verification, the simulated groundwater flow can reflect actual groundwater situation. Finally, when specific five rainfall events impose on the ground, groundwater recharge can be determined using the groundwater model.

Lin, Zong Sheng; Chen, Jui-Sheng; Jang, Cheng-Shin

2014-05-01

19

Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill Hole Data in Yucca Flat, Nye County, Nevada  

Microsoft Academic Search

Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site (NTS) in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of

Donald S. Sweetkind; Ronald M. Drake II

2007-01-01

20

Spatial and temporal characteristics of aridity conditions in Tarim Basin, China  

NASA Astrophysics Data System (ADS)

Arid ecosystems are very sensitive to a variety of physical, chemical and biological degradation processes. Tarim Basin, the biggest endorheic basin in the Central Asia continent, is considered as one of the least water-endowed regions in the world and arid and semi-arid environmental conditions are dominant. For the purposes of the convention, arid, semi-arid and dry sub-humid areas were defined as "areas, other than polar and sub-polar regions, in which the ratio of annual precipitation to potential evapotranspiration falls within the range from 0.05 to 0.65." In this study, the Aridity Index (AI), the ratio of precipitation and land surface temperature, was also adopted as the base method for determining dry land types and thereby delineating boundaries and showing changes of aridity conditions in Tarim Basin. Here, precipitation is from TRMM/PR, and land surface temperature is from Modis LST. To analyze the spatial and temporal variations of arid environmental conditions in Tarim basin, we calculated the yearly aridity index (the ratio of total yearly rainfall to yearly mean Land Surface Temperature) based on the accumulated monthly precipitation and the monthly Land Surface Temperature in growing season for the period 2000-2009. The results indicated it is possible to work out an aridity index map with more detailed spatial patterns, which is valuable for identifying human impacts by associated with vegetation and soil moisture characters.

Sun, Zhandong; Chang, Ni-Bin; Opp, Christian; Hennig, Thomas

2010-10-01

21

Migration of recharge waters downgradient from the Santa Catalina Mountains into the Tucson basin aquifer, Arizona, USA  

Microsoft Academic Search

Aquifers in the arid alluvial basins of the southwestern U.S. are recharged predominantly by infiltration from streams and playas within the basins and by water entering along the margins of the basins. The Tucson basin of southeastern Arizona is such a basin. The Santa Catalina Mountains form the northern boundary of this basin and receive more than twice as much

Erin E. B. Cunningham; Austin Long; Chris Eastoe; R. L. Bassett

1998-01-01

22

Major ions chemistry of groundwater in the arid region of Zhangye Basin, northwestern China  

Microsoft Academic Search

As one of the most arid regions in the world, the study area, Zhangye Basin is located in the middle reaches of the Heihe\\u000a River, northwest China. Besides aridity, rapid social and economic development also stimulates greater demand for water, which\\u000a is gradually fulfilled by groundwater extraction. In this study, the conventional hydrochemical techniques and statistical\\u000a analyses were applied to

Juan Chang; Genxu Wang

2010-01-01

23

Hydrogeology and simulation of flow between the alluvial and bedrock aquifers in the upper Black Squirrel Creek basin, El Paso County, Colorado  

USGS Publications Warehouse

Anticipated increases in pumping from the bedrock aquifers in El Paso County potentially could affect the direction and rate of flow between the alluvial and bedrock aquifers and lower water levels in the overlying alluvial aquifer. The alluvial aquifer underlies about 90 square miles in the upper Black Squirrel Creek Basin of eastern El Paso County. The alluvial aquifer consists of unconsolidated alluvial deposits that unconformably overlie siltstones, sandstones, and conglomerate (bedrock aquifers) and claystone, shale, and coal (bedrock confining units) of the Denver Basin. The bedrock aquifers (Dawson, Denver, Arapahoe, and Laramie-Fox Hills aquifers) are separated by confining units (upper and lower Denver and the Laramie confining units) and overlie a relatively thick and impermeable Pierre confining unit. The Pierre confining unit is assumed to be a no-flow boundary at the base of the alluvial/ bedrock aquifer system. During 1949-90, substantial water-level declines, as large as 50 feet, in the alluvial aquifer resulted from withdrawals from the alluvial aquifer for irrigation and municipal supplies. Average recharge to the alluvial aquifer from infiltration of precipitation and surface water was an estimated 11.97 cubic feet per second and from the underlying bedrock aquifers was an estimated 0.87 cubic foot per second. Water-level data from eight bedrock observation wells and eight nearby alluvial wells indicate that, locally, the alluvial and bedrock aquifers probably are hydraulically connected and that the alluvial aquifer in the upper Black Squirrel Creek Basin receives recharge from the Denver and Arapahoe aquifers but-locally recharges the Laramie-Fox Hills aquifer. Subsurface-temperature profiles were evaluated as a means of estimating specific discharge across the bedrock surface (the base of the alluvial aquifer). However, assumptions of the analytical method were not met by field conditions and, thus, analyses of subsurface-temperature profiles did not reliably estimate specific discharge across the bedrock surface. The vertical hydraulic diffusivity of a siltstone and sandstone in the lower Denver confining unit was estimated, by an aquifer test, to be about 8 x 10'4 square foot per day. Physical and chemical characteristics of water from the bedrock aquifers in the study area generally differ from the physical and chemical characteristics of water from the alluvial aquifer, except for the physical and chemical characteristics of water from one bedrock well, which is completed in the Laramie-Fox Hills aquifer. In the southern part of the study area, physical and chemical characteristics of ground water indicate downward flow of water from the alluvial aquifer to the Laramie-Fox Hills aquifer. A three-dimensional numerical model was used to evaluate flow of water between the alluvial aquifer and underlying bedrock. Simulation of steady-state conditions indicates that flow from the bedrock aquifers to the alluvial aquifer was about 7 percent of recharge to the alluvial aquifer, about 0.87 cubic foot per second. The potential effects of withdrawal from the alluvial and bedrock aquifers at estimated (October 1989 to September 1990) rates and from the bedrock aquifers at two larger hypothetical rates were simulated for a 50-year projection period. The model simulations indicate that water levels in the alluvial aquifer will decline an average of 8.6 feet after 50 years of pumping at estimated October 1989 to September 1990 rates. Increases in withdrawals from the bedrock aquifers in El Paso County were simulated to: (1) Capture flow that currently discharges from the bedrock aquifers to springs and streams in upland areas and to the alluvial aquifer, (2) induce flow downward from the alluvial aquifer, and (3) accelerate the rate of waterlevel decline in the alluvial aquifer.

Watts, K.R.

1995-01-01

24

Hydrochemical Differentiation of Salinisation Process of the Water in Endoreic Semi-Arid Basin: Case of Rémila Basin, Algeria  

Microsoft Academic Search

The aim of this study is to determine and treat a hierarchical basis of the various mechanisms responsible for the space variation of the water quality in a endoreic semi-arid basin. The water chemistry showed a large variability in space and time. The total dissolved solid (TDS) in water increases from upstream to downstream due to the effect of the

Houha Belgacem; Kherici Nacer; Kachi Slimane; Valles Vincent

25

Hydrogeologic features of the alluvial deposits in the Nowood River drainage area, Bighorn Basin, Wyoming  

USGS Publications Warehouse

In the Nowood River drainage area, Wyoming, the principal deposits comprising the alluvial aquifer include the flood-plain and younger (generally undissected) alluvial-fan deposits and a unique boulder-fan gravel. Other deposits mapped, but virtually nonwater yielding, are the older (dissected) alluvial-fan, pediment, and terrace deposits. Terraces are capped by gravel and form levels at 30-40, 45-100, 120-150, 200-260, and 280-330 feet above the Nowood River. The thickness of the alluvial aquifer indicated from the sparse well-log data and 42 surface resistivity measurements is between 25 and 50 feet along the Nowood River and more than 60 feet along Tensleep and Paint Rock Creeks. The resistivity measurements indicate a buried bedrock ridge below the boulder-fan gravel between Paint Rock and Medicine Lodge Creeks and a buried channel filled by alluvium along Tensleep Creek. Well yields from the alluvial aquifer are estimated to be low. The most favorable areas for ground-water development are from the flood-plain alluvium along Tensleep Creek and from the boulder-fan gravel and adjoining flood-plain alluvium along Paint Rock and Medicine Creeks. Along the Nowood River the flood-plain alluvium, although its yields are small, has the best potential for ground-water development. (Kosco-USGS)

Cooley, M.E.; Head, William J.

1979-01-01

26

Preliminary results of chronostratigraphic field work, OSL-dating and morphogenetic reconstruction of an alluvial apron at Alborz southern foothill, Damghan basin, Iran  

NASA Astrophysics Data System (ADS)

Here we present preliminary results of a chronostratigraphic study of an alluvial fan in the Damghan Basin, northern Iran. The basin sediments date back to the Mio- and Pliocene and therefore represent the starting point of alluvial fan aggradation. Today, the still active alluvial fans prograde from the Albors Mountain ranges and sit on the older sediment bodies. In this study, our focus is on the late Pleistocene to Holocene alluvial fan sedimentation history. The upper stratigraphy of the alluvial fans and intercalated lake deposits is characterized by six individual layers of gravels and fines, representing six different stratigraphic units. These units are described and classified by detailed geomorphological and stratigraphic mapping. To establish an alluvial fan chronology, six profiles were sampled for OSL dating. As expected, due to the high-energy transport system of alluvial fan aggradation in semi-desert environments, OSL dating of these sediments is challenging due to the problem of insufficient bleaching. Consequently, most of the samples are interpreted as maximum ages. However, the measurements show a consistent internal age structure and the overall OSL-based chronology is in agreement with the age model derived from our geomorphological analysis. As a first interpretation, based on surveyed geomorphological features and chronological analysis, we could identify seven morphodynamic phases, leading to a genetic model of alluvial fan aggradation. The oldest Pleistocene age estimate is derived from a former lake terrace. The following ages represent ongoing lake sediment deposition and the development of a proximal and mid-fan gravel cover. After the youngest lake deposits were accumulated within the Holocene, the lake starts to retreat and small alluvial fans are filling up the former lake bottom. This last sedimentation phase can be divided in at least two sub-phases, probably coupled to a lateral shifting of the active depositional lobe and to the abandonment and shallow incision of mid fan surfaces.

Büdel, Christian; Fuchs, Markus; Majid Padashi, Seyed; Baumhauer, Roland

2014-05-01

27

Hydrogeologic features of the alluvial deposits in the Owl Creek Valley, Bighorn Basin, Wyoming  

USGS Publications Warehouse

The alluvial acquifer principally of the flood-plain alluvium and part of the Arapahoe Ranch terrace deposits and consists subordinately of alluvial-fan deposits. Thickness of the alluvial aquifer is generally 20 to 40 feet. Dissolved-solids concentration of water in the alluvial aquifer ranges from about 500 to more than 3,000 milligrams per liter. The most favorable areas for groundwater development are the flood-plain alluvium and part of the Arapahoe Ranch terrace deposits; however, in much of these units, the water contains more than 2,000 milligrams per liter of dissolved solids. Measurements of specific conductance of the flow of Owl Creek indicate a progressive increase in the down stream direction and range between 15 and 355 micromhos per centimeter at 25C per mile. The increases are due to return flow of irrigation water, inflow from tributaries, and inflow from groundwater. Conspicuous terraces in Owl Creek Valley included an unnamed terrace at 500 feet above Owl Creek, the Embar Ranch terrace 160 to 120 feet above the creek, and the Arapahoe Ranch terrace 50 to 20 feet above the creek. (USGS)

Cooley, M.E.; Head, W.J.

1982-01-01

28

Mapping and assessment of degraded land in the Heihe River Basin, arid northwestern China  

PubMed Central

Land degradation is a great threat in the Heihe River Basin, located in the arid inland of northwestern China and land desertification is one of the main aspects of environmental changes in this basin. Previous studies have focused on water resource utilization and soil erosion, but the status of degraded land in the Heihe River Basin, such as its distribution, extent and precise characteristics is often inadequately known. Based on field observations and TM images from the year 2003, this study provides classification and evaluation information concerning the degraded land in the basin of the Heihe River. There are five types of degraded land types in the Heihe River Basin: water eroded in the southern mountains, sandified and vegetation degraded near the oases, aridized in the low reaches, and salinized in the lowlands. The total degraded area covers 29,355.5 km2, 22.58% of the land in the study area. Finally, degraded land in the Heihe River Basin was evaluated according to changes in the physical structure and chemical components of soils, land productivity, secondary soil salt, and water conditions.

Qi, Shanzhong; Cai, Yumin

2007-01-01

29

The ecological features and significance of hydrology within arid inland river basins of China  

Microsoft Academic Search

Hydrology and ecology are two important factors affecting the rational utilization of limited water resources within the\\u000a arid inland basins of China. They depend on, are influenced by, and interact with each other. But, the functions and significance\\u000a of the hydrological ecology vary from upper through intermediate to lower reaches. Abundant rainfall and large runoff in the\\u000a upper regions favor

W. Genxu; C. Guodong

1999-01-01

30

S2-Project: Near-fault earthquake ground motion simulation in the Sulmona alluvial basin  

NASA Astrophysics Data System (ADS)

Recently the Italian Department of Civil Protection (DPC), in cooperation with Istituto Nazionale di Geofisica e Vulcanologia (INGV) has promoted the 'S2' research project (http://nuovoprogettoesse2.stru.polimi.it/) aimed at the design, testing and application of an open-source code for seismic hazard assessment (SHA). The tool envisaged will likely differ in several important respects from an existing international initiative (Open SHA, Field et al., 2003). In particular, while "the OpenSHA collaboration model envisions scientists developing their own attenuation relationships and earthquake rupture forecasts, which they will deploy and maintain in their own systems" , the main purpose of S2 project is to provide a flexible computational tool for SHA, primarily suited for the needs of DPC, which not necessarily are scientific needs. Within S2, a crucial issue is to make alternative approaches available to quantify the ground motion, with emphasis on the near field region. The SHA architecture envisaged will allow for the use of ground motion descriptions other than those yielded by empirical attenuation equations, for instance user generated motions provided by deterministic source and wave propagation simulations. In this contribution, after a brief presentation of Project S2, we intend to illustrate some preliminary 3D scenario simulations performed in the alluvial basin of Sulmona (Central Italy), as an example of the type of descriptions that can be handled in the future SHA architecture. In detail, we selected some seismogenic sources (from the DISS database), believed to be responsible for a number of destructive historical earthquakes, and derive from them a family of simplified geometrical and mechanical source models spanning across a reasonable range of parameters, so that the extent of the main uncertainties can be covered. Then, purely deterministic (for frequencies < 2Hz) and hybrid deterministic- stochastic source and propagation simulations are carried out for different fault rupture scenarios (but including important features such as the dominant near-surface geology), and the results in terms of representative ground motion parameters appropriately enveloped. The fully 3D problem is solved using the Spectral Element (SE) method, extensively published by Faccioli and his co-workers, and Quarteroni and co- workers, starting from 1996, and the computational code GeoELSE (http://GeoELSE.stru.polimi.it/). Finally, numerical results are compared with available data and attenuation relationships of peak values of ground motion in the near-fault regions elsewhere. Based on the results of this work, the unfavorable interaction between fault rupture, radiation mechanism and complex geological conditions may give rise to large values of peak ground velocity (exceeding 1 m/s) even in low-to-moderate seismicity areas, and therefore increase considerably the level of seismic risk, especially in highly populated and industrially active regions, such as the Central Italy.

Faccioli, E.; Stupazzini, M.; Galadini, F.; Gori, S.

2008-12-01

31

Water resource development and its influence on the environment in arid areas of China—the case of the Hei River basin  

Microsoft Academic Search

This paper outlines the influences of water resource development on the ecology of the arid regions of north-west China. The Hei River basin served as a case study. Water resources in the arid zones of north-west China, which have an inland hydrological basin as their unit, form relatively independent ecosystems. In such basins, surface runoff flowing out of the mountain

Wang Genxu; Cheng Guodong

1999-01-01

32

Predicting the Affects of Climate Change on Evapotranspiration and Agricultural Productivity of Semi-arid Basins  

NASA Astrophysics Data System (ADS)

Many arid and semi-arid regions around the world are experiencing water shortages that have become increasingly problematic. Since the late 1800s, upstream diversions in Nevada's Walker River have delivered irrigation supply to the surrounding agricultural fields resulting in a dramatic water level decline of the terminal Walker Lake. Salinity has also increased because the only outflow from the lake is evaporation from the lake surface. The Heihe River basin of northwestern China, a similar semi-arid catchment, is also facing losses from evaporation of terminal locations, agricultural diversions and evapotranspiration (ET) of crops. Irrigated agriculture is now experiencing increased competition for use of diminishing water resources while a demand for ecological conservation continues to grow. It is important to understand how the existing agriculture in these regions will respond as climate changes. Predicting the affects of climate change on groundwater flow, surface water flow, ET and agricultural productivity of the Walker and Heihe River basins is essential for future conservation of water resources. ET estimates from remote sensing techniques can provide estimates of crop water consumption. By determining similarities of both hydrologic cycles, critical components missing in both systems can be determined and predictions of impacts of climate change and human management strategies can be assessed.

Peri, L.; Tyler, S. W.; Zheng, C.; Pohll, G. M.; Yao, Y.

2013-12-01

33

Revisiting a classification scheme for U.S.-Mexico alluvial basin-fill aquifers.  

PubMed

Intermontane basins in the Trans-Pecos region of westernmost Texas and northern Chihuahua, Mexico, are target areas for disposal of interstate municipal sludge and have been identified as possible disposal sites for low-level radioactive waste. Understanding ground water movement within and between these basins is needed to assess potential contaminant fate and movement. Four associated basin aquifers are evaluated and classified; the Red Light Draw Aquifer, the Northwest Eagle Flat Aquifer, the Southeast Eagle Flat Aquifer, and the El Cuervo Aquifer. Encompassed on all but one side by mountains and local divides, the Red Light Draw Aquifer has the Rio Grande as an outlet for both surface drainage and ground water discharge. The river juxtaposed against its southern edge, the basin is classified as a topographically open, through-flowing basin. The Northwest Eagle Flat Aquifer is classified as a topographically closed and drained basin because surface drainage is to the interior of the basin and ground water discharge occurs by interbasin ground water flow. Mountains and ground water divides encompass this basin aquifer on all sides; yet, depth to ground water in the interior of the basin is commonly >500 feet. Negligible ground water discharge within the basin indicates that ground water discharges from the basin by vertical flow and underflow to a surrounding basin or basins. The most likely mode of discharge is by vertical, cross-formational flow to underlying Permian rocks that are more porous and permeable and subsequent flow along regional flowpaths beneath local ground water divides. The Southeast Eagle Flat Aquifer is classified as a topographically open and drained basin because surface drainage and ground water discharge are to the adjacent Wildhorse Flat area. Opposite the Eagle Flat and Red Light Draw aquifers is the El Cuervo Aquifer of northern Chihuahua, Mexico. The El Cuervo Aquifer has interior drainage to Laguna El Cuervo, which is a phreatic playa that also serves as a focal point of ground water discharge. Our evidence suggests that El Cuervo Aquifer may lose a smaller portion of its discharge by interbasin ground water flow to Indian Hot Springs, near the Rio Grande. Thus, El Cuervo Aquifer is a topographically closed basin that is either partially drained if a component of its ground water discharge reaches Indian Hot Springs or undrained if all its natural ground water discharge is to Laguna El Cuervo. PMID:16149972

Hibbs, Barry J; Darling, Bruce K

2005-01-01

34

Fault-sourced alluvial fans and their interaction with axial fluvial drainage: An example from the Plio-Pleistocene Upper Valdarno Basin (Tuscany, Italy)  

NASA Astrophysics Data System (ADS)

The present study deals with the fault-sourced, alluvial-fan deposits of the Plio-Pleistocene Upper Valdarno Basin (Northern Apennines, Italy). Different phases of alluvial fan aggradation, progradation and backstep are discussed as possible effects of the interaction among fault-generated accommodation space, sediment supply and discharge variations affecting the axial fluvial drainage. The Upper Valdarno Basin, located about 35 km SE of Florence, is filled with 550 m palustrine, lacustrine and alluvial deposits forming four main unconformity-bounded units (i.e. synthems). The study alluvial-fan deposits belong to the two uppermost synthems (Montevarchi and Torrente Ciuffenna synthems) and are Early to Middle Pleistocene in age. These deposits are sourced from the fault-bounded, NE margin of the basin and interfinger with axial fluvial deposits. Alluvial fan deposits of the Montevarchi Synthem consist of three main intervals: i) a lower interval, which lacks any evidence of a depositional trend and testify balance between the subsidence rate (i.e. fault activity) and the amount of sediment provided from the margin; ii) a coarsening-upward middle interval, pointing to a decrease in subsidence rate associated with an augment in sediment supply; iii) a fining-upward, upper interval (locally preserved), documenting a phase of tectonic quiescence associated with a progressive re-equilibration of the tectonically-induced morphological profile. The basin-scale unconformity, which separates the Montevarchi and Torrente Ciuffenna synthems was due to the entrance of the Arno River into the basin as consequence of a piracy. This event caused a dramatic increase in water discharge of the axial fluvial system, and its consequent embanking. Such an erosional surface started to develop in the axial areas, and propagated along the main tributaries, triggering erosion of the alluvial fan deposits. Alluvial-fan deposits of the Torrente Ciuffenna Synthem accumulated above the unconformity during a phase of tectonic quiescence, and show a fining-upward depositional trend. This trend was generated by a progressive decrease in sediment supply stemming out from upstream migration of the knickpoints developed during the embanking of the axial system.

Fidolini, Francesco; Ghinassi, Massimiliano; Aldinucci, Mauro; Billi, Paolo; Boaga, Jacopo; Deiana, Rita; Brivio, Lara

2013-05-01

35

Quantifying the effect of hydrologic variability on sediment transport in alluvial rivers  

NASA Astrophysics Data System (ADS)

Existing equations for predicting the time-averaged bedload sediment flux in alluvial rivers do not explicitly include variations in discharge. In this study, we develop an analytical equation for the time-averaged sediment flux in an alluvial river that incorporates the instantaneous sediment transport equation and the frequency-size distribution of flood events, taking into account both the mean and coefficient of variation of discharge for a channel with a prescribed slope and grain size distribution. Two applications of the resulting equation are then considered. First, the geomorphic effectiveness of end-member climate regimes is considered, taking into account the inverse relationship between the mean and coefficient of variation of discharge in alluvial rivers. The results indicate that an alluvial river located in a humid climate with high effective annual runoff and low variation in discharge transports more sediment per unit time than the same river located in a more arid basin. Second, the effective discharge and its corresponding return period are calculated using the analytical equation for alluvial rivers in climates that range between arid and humid end-members. Rivers in humid climates have effective discharge return periods of months to decades, while the return periods for extremely arid climates can be up to several hundred years.

Engelder, T. M.; Pelletier, J. D.

2010-12-01

36

Stages of the development of alluvial soils in the Bikin River valley (the Amur River basin) in the Middle and Late Holocene  

NASA Astrophysics Data System (ADS)

The evolution of alluvial soils in the Bikin River basin in the Middle and the Late Holocene is discussed. On the basis of biostratigraphic data, four pollen zones have been identified in the soils: Pinus koraiensis- Picea, Pinus koraiensis- Quercus- Sphagnum, Betula- Alnus- Alnaster, and Quercus. A set of soil characteristics (texture, acid-base properties, and the organic matter content and group composition) have also been determined. These data allow us to distinguish between four stages of alluvial soil formation in the Bikin River basin. They characterize humus-forming conditions in the Middle and the Late Holocene. Reconstruction of ancient vegetation conditions makes it possible to conclude that climatic fluctuations were synchronous with changes in the soil characteristics. During the Holocene climatic optimum, humus was formed in a slightly acid medium, and humic acids predominated. In cold periods with increased precipitation, fulvic acids predominated in the composition of humus, and the portion of insoluble residue was high because of the more acid medium. The stages of alluvial pedogenesis in the Bikin River valley follow the sedimentation model of soil evolution. Alluvial gray humus soils evolved from typical gray humus soils under meadow communities during warm periods to gleyic and gleyed soils under birch shrubs and alder groves in colder and wetter periods.

Nazarkina, A. V.; Belyanin, P. S.

2014-05-01

37

Ground water in the alluvial deposits of Cottonwood Creek Basin, Oklahoma  

USGS Publications Warehouse

Cottonwood Creek basin is a 377 square mile area in central Oklahoma. The rim of the basin has altitudes as high as 1,300 feet, and the mouth is at an altitude of 910. Deposits of Quaternary age consist of alluvium along the stream courses and high terrace deposits along the southern rim of the basin. The alluvium contains a high percentage of clay and silt, ranges in thickness from a few inches to 40 feet, and underlies about 36 square miles of the basin. Sandstone, siltstone, and shale of Permian age, which form the bedrock, consist of the Garber sandstone along the eastern edge, the Hennessey shale through the central part, and Flowerpot shale along the western edge. Replenishment of water in the alluvium is from precipitation, lateral seepage and runoff from adjoining areas, and infiltration from the stream channels during high flows. The major use of ground water in the alluvium is transpiration by cottonwood and willow trees. Virtually no water is withdrawn from the alluvium by wells. (available as photostat copy only)

Stacy, B.L.

1960-01-01

38

Conceptual model of the Great Basin carbonate and alluvial aquifer system  

USGS Publications Warehouse

Prior to groundwater development, total groundwater discharge was estimated to be 4,200,000 acre-ft/yr with an uncertainty of ± 30 percent (± 1,300,000 acre-ft/yr). The two major components of discharge are evapotranspiration and springs. Estimated groundwater discharge to evapotranspiration and springs for predevelopment conditions was 1,800,000 acre-ft/yr and 990,000 acre-ft/yr, respectively. Other forms of discharge include discharge to basin-fill streams/lakes/reservoirs (660,000 acre-ft/yr), disc

Editors: Heilweil, Victor M.; Brooks, Lynette E.

2011-01-01

39

Estimating basin-wide hydraulic parameters of a semi-arid mountainous watershed by recession-flow analysis  

E-print Network

hydraulic parameters, hydraulic conductivity or transmissivity is the most problematic to obtain, in part. Usually, hydraulic conductivity is unsatis- factorily estimated based on laboratory measurements, whichEstimating basin-wide hydraulic parameters of a semi-arid mountainous watershed by recession

Walter, M.Todd

40

Stable Water Isotope Tracing and Model Evaluation in Large Basins: the `` Special Case'' of Semi-Arid Catchments  

Microsoft Academic Search

The use of stable water isotopes in hydro-climate monitoring and modelling offers a new means of measuring and parameterizing critical processes. Here we review these specifically for the case of semi-arid basins where water resources are essential for potable supply and agriculture around the world. The verity and performance of existing models is examined using observations and simulations of stable

A. Henderson-Sellers; P. Airey; K. McGuffie; J. Bradd; D. Stone

2004-01-01

41

Sustainability of Water Resources in Arid Ecosystems: A View from Hei River Basin, China (Invited)  

NASA Astrophysics Data System (ADS)

The northwest of China is characterized by an arid climate and fragile ecosystems. With irrigated agriculture, the region is a prolific producer of cotton, wheat, and maize with some of the highest output per acre in the country. The region is also rich in ore deposits, with the reserves of numerous minerals ranked at or near the top in the country. However, the sustainability of irrigated agriculture and economic development in the region is threaten by severe eco-environmental problems resulting from both global changes and human activities, such as desertification, salinization, groundwater depletion, and dust storms. All these problems are a direct consequence of water scarcity. As global warming accelerates and rapid economic growth continues, the water shortage crisis is expected to worsen. To improve the bleak outlook for the health of ecosystem and environment in northwest China, the Chinese government has invested heavily in ecosystem restoration and watershed management in recent years. However, the effectiveness of such measures and actions depends on scientific understanding of the complex interplays among ecological, hydrological and socioeconomic factors. This presentation is intended to provide an overview of a major new research initiative supported by the National Natural Science Foundation of China to study the integration of ecological principles, hydrological processes and socioeconomic considerations toward more sustainable exploitation of surface water and groundwater resources in the Hei River Basin in northwest China. The Hei River Basin is an inland watershed located at the center of the arid region in East Asia, stretching from Qilianshan Mountains in the south to the desert in the north bordering China’s Inner Mongolia Autonomous Region and Mongolia. The total area of Hei River Basin is approximately 130,000 km2. The research initiative builds on existing research infrastructure and ecohydrological data and seeks to reveal complex interactions and feedbacks between ecosystem functioning and water resources in an arid inland watershed. The findings will provide scientific basis for sustainable water resource management that maximizes the economic benefits without irreparably damaging the ecosystem.

Zheng, C.; Cheng, G.; Xiao, H.; Ma, R.

2009-12-01

42

Simulation of Carbon-14 Migration Through a Thick Unsaturated Alluvial Basin Resulting from an Underground Nuclear Explosion  

NASA Astrophysics Data System (ADS)

Yucca Flat is one of several areas on the Nevada Test Site that was used for underground nuclear testing. Extensive testing performed in the unsaturated and saturated zones have resulted in groundwater contamination and surface subsidence craters in the vicinity of the underground test areas. Simulation of multiphase 14C transport through the thick Yucca Flat alluvial basin was performed to estimate the magnitude of radionuclide attenuation occurring within the unsaturated zone. Parameterization of the 14C transport in the multiphase flow and transport simulator (FEHM) was verified with experimental data collected from a large unsaturated soil column experiment. The experimental data included 14C as a radio-labeled bicarbonate solution, SF6 gas, and lithium bromide solution breakthroughs. Two representative simulation cases with working points located at shallow and deep depths relative to the water table were created to investigate the impact of subsidence crater-enhanced recharge, crater-playa areal extent, gas-phase partitioning, solid-phase partitioning, and a reduced permeability/porosity compressed zone created during the explosion on 14C transport. The representative shallow test had a detonation point located 175 m below land surface, and the deep test had a working point 435 m below land surface in a 500 m deep unsaturated zone. Carbon-14 transport is influenced by gas-phase diffusion and sorption within the alluvium. Gas-phase diffusion is an attenuation mechanism that transports 14C gas as 14CO2 throughout the unsaturated zone and exposes it to a large amount of soil moisture, resulting in dilute concentrations. The simulations indicated that the majority of the 14C inventory remains in the unsaturated zone over a 1,000-year time period after detonation because gas-phase diffusion moves the bulk of the 14C away from the higher recharge occurring in crater playas. Retardation also plays a role in slowing advective aqueous phase transport to the water table.

Martian, P.; Larentzos, J.

2008-12-01

43

Geohydrology, water quality, and preliminary simulations of ground-water flow of the alluvial aquifer in the Upper Black Squirrel Creek basin, El Paso County, Colorado  

USGS Publications Warehouse

The upper Black Squirrel Creek basin in eastern El Paso County, Colorado, is underlain by an alluvial aquifer and four bedrock aquifers. Groundwater pumpage from the alluvial aquifer has increased since the mid-1950's, and water level declines have been substantial; the bedrock aquifers virtually are undeveloped. Groundwater pumpage for domestic, stock, agricultural, and municipal uses have exceeded recharge for the past 25 years. The present extent of the effect of pumpage on the alluvial aquifer was evaluated, and a groundwater flow model was used to simulate the future effect of continued pumpage on the aquifer. Measured water level declines from 1974 through 1984 were as much as 30 ft in an area north of Ellicott, Colorado. On the basis of the simulations, water level declines from October 1984 to April 1999 north of Ellicott might be as much as 20 to 30 ft and as much as 1 to 10 ft in most of the aquifer. The groundwater flow models provided a means of evaluating the importance of groundwater evapotranspiration at various stages of aquifer development. Simulated groundwater evapotranspiration was about 43% of the outflow from the aquifer during predevelopment stages but was less than 3% of the outflow from the aquifer during late-development stages. Analyses of 36 groundwater samples collected during 1984 indicated that concentrations of dissolved nitrite plus nitrate as nitrogen generally were large. Samples from 5 of the 36 wells had concentrations of dissolved nitrite plus nitrate as nitrogen that exceeded drinking water standards. Water from the alluvial aquifer generally is of suitable quality for most uses. (USGS)

Buckles, D.R.; Watts, K.R.

1988-01-01

44

The content of chemical elements in alluvial soils and bottom sediments of the Urkan River (the Amur River basin)  

NASA Astrophysics Data System (ADS)

The distribution patterns of the chemical elements in the bottom sediments and alluvial soils of the Urkan River valley (one of the largest tributaries of the Zeya River, a tributary of the Amur River) have been examined. It is shown that the concentrations of the chemical elements in the bottom sediments generally correspond to those in the bedrocks composing the river catchment and in the upper part of the continental earth's crust, though the accumulation of most of the elements in the bottom sediments is somewhat lower. The composition of the microelements in the alluvial soils is mainly determined by the composition of the microelements in the bottom sediments. The alluvial soils are somewhat enriched in Mn, Zn, Co, and Cu, which is related to the biological accumulation of these elements entering the trophic chains.

Sorokina, O. A.; Zarubina, N. V.

2013-06-01

45

Survey of Martian Alluvial Fans  

NASA Astrophysics Data System (ADS)

Recent higher resolution images of the Martian surface reveal another complex geomorphic surface process - alluvial fans. Alluvial fans composed of water-transported, loose sediment deposited as the flow moves from steep, eroding terrain to low-gradient depositional basins. Martian alluvial fans are concentrated along crater rims where they erode into the higher surround topography depositing sediment into the crater interior. Initial work by Moore and Howard [2004] examined some of these fans in a band from 0-30 S. Their initial results included fan statistics, such as area and slope, and indicated that the fans were clustered in discrete areas. However, this survey was hampered by incomplete image coverage. We present the progress of our continuing, planet wide survey of alluvial fans. Specifically we focus on understanding if alluvial fans are indeed clustered in particular areas and if so, why. In addition, we expand fan statistics to include a comparison of fan volume to eroded area.

Kraal, E. R.; Moore, J.; Asphaug, E.; Howard, A.

2004-12-01

46

The influence of river regulation and land use on floodplain forest regeneration in the semi-arid upper Colorado River Basin, USA  

USGS Publications Warehouse

Flow regulation effects on floodplain forests in the semi-arid western United States are moderately well understood, whereas effects associated with changes in floodplain land use are poorly documented. We mapped land cover patterns from recent aerial photos and applied a classification scheme to mainstem alluvial floodplains in 10 subjectively selected 4th order hydrologic units (subbasins) in the Upper Colorado River Basin (UCRB) in order to document land use patterns (floodplain development) and assess their effects on Fremont cottonwood forest (CF) regeneration. Three of the mainstem rivers were unregulated, five were moderately regulated and two were highly regulated. We classified polygons as Undeveloped (with two categories, including CF) and Developed (with five categories). We ground-truthed 501 randomly selected polygons (4-28% of the floodplain area in each subbasin) to verify classification accuracy and to search for cottonwood regeneration, defined as stands established since regulation began or 1950, whichever is most recent. From 40% to 95% of the floodplain area remained undeveloped, but only 19-70% of the floodplain area was classified as forest. Regeneration occupied a mean of 5% (range 1-17%) of the floodplain. The likelihood of the presence of regeneration in a polygon was reduced 65% by development and independently in a complex manner by flow regulation. Our analyses indicate that floodplain forests may be in jeopardy on both regulated and unregulated rivers and that information on historical forest extent is needed to better understand their current status in the UCRB. Conservation efforts need to be coordinated at a regional level and address the potentially adverse affects of both flow regulation and floodplain development.

Northcott, K.; Andersen, D. C.; Cooper, D. J.

2007-01-01

47

The Italian Project S2 - Task 4:Near-fault earthquake ground motion simulation in the Sulmona alluvial basin  

NASA Astrophysics Data System (ADS)

Recently the Italian Department of Civil Protection (DPC), in cooperation with Istituto Nazionale di Geofisica e Vulcanologia (INGV) has promoted the 'S2' research project (http://nuovoprogettoesse2.stru.polimi.it/) aimed at the design, testing and application of an open-source code for seismic hazard assessment (SHA). The tool envisaged will likely differ in several important respects from an existing international initiative (Open SHA, Field et al., 2003). In particular, while "the OpenSHA collaboration model envisions scientists developing their own attenuation relationships and earthquake rupture forecasts, which they will deploy and maintain in their own systems", the main purpose of S2 project is to provide a flexible computational tool for SHA, primarily suited for the needs of DPC, which not necessarily are scientific needs. Within S2, a crucial issue is to make alternative approaches available to quantify the ground motion, with emphasis on the near field region. The SHA architecture envisaged will allow for the use of ground motion descriptions other than those yielded by empirical attenuation equations, for instance user generated motions provided by deterministic source and wave propagation simulations. In this contribution, after a brief presentation of Project S2, we intend to illustrate some preliminary 3D scenario simulations performed in the alluvial basin of Sulmona (Central Italy), as an example of the type of descriptions that can be handled in the future SHA architecture. In detail, we selected some seismogenic sources (from the DISS database), believed to be responsible for a number of destructive historical earthquakes, and derive from them a family of simplified geometrical and mechanical source models spanning across a reasonable range of parameters, so that the extent of the main uncertainties can be covered. Then, purely deterministic (for frequencies < 2Hz) and hybrid deterministic- stochastic source and propagation simulations are carried out for different fault rupture scenarios (but including important features such as the dominant near-surface geology), and the results in terms of representative ground motion parameters appropriately enveloped. The fully 3D problem is solved using the Spectral Element (SE) method, extensively published by Faccioli and his co-workers, and Quarteroni and co- workers, starting from 1996, and the computational code GeoELSE (Stupazzini et al., 2009; http://GeoELSE.stru.polimi.it/). Finally, numerical results are compared with available data and attenuation relationships of peak values of ground motion in the near-fault regions elsewhere. Based on the results of this work, the unfavorable interaction between fault rupture, radiation mechanism and complex geological conditions may give rise to large values of peak ground velocity (exceeding 1 m/s) even in low-to-moderate seismicity areas, and therefore increase considerably the level of seismic risk, especially in highly populated and industrially active regions, such as the Central Italy. Faccioli E., Maggio F., Paolucci R. and Quarteroni A. (1997),2D and 3D elastic wave propagation by a pseudo-spectral domain decomposition method, Journal of Seismology, 1, 237-251. Field, E.H., T.H. Jordan, and C.A. Cornell (2003), OpenSHA: A Developing Community-Modeling Environment for Seismic Hazard Analysis, Seism. Res. Lett. 74, 406-419. Stupazzini M., R. Paolucci, H. Igel (2009), Near-fault earthquake ground motion simulation in the Grenoble Valley by a high-performance spectral element code, accepted for publication in Bull. of the Seism. Soc. of America.

Stupazzini, M.; Smerzini, C.; Cauzzi, C.; Faccioli, E.; Galadini, F.; Gori, S.

2009-04-01

48

How Widely Applicable is River Basin Management? An Analysis of Wastewater Management in an Arid Transboundary Case  

NASA Astrophysics Data System (ADS)

The basin scale has been promoted universally as the optimal management unit that allows for the internalization of all external effects caused by multiple water uses. However, the basin scale has been put forward largely on the basis of experience in temperate zones. Hence whether the basin scale is the best scale for management in other settings remains questionable. To address these questions this paper analyzes the economic viability and the political feasibility of alternative management options in the Kidron/Wadi Nar region. The Kidron/Wadi Nar is a small basin in which wastewater from eastern Jerusalem flows through the desert to the Dead Sea. Various options for managing these wastewater flows were analyzed ex ante on the basis of both a cost benefit and a multi-criteria analysis. The paper finds that due to economies of scale, a pure basin approach is not desirable from a physical and economic perspective. Furthermore, in terms of political feasibility, it seems that the option which prompts the fewest objections from influential stakeholder groups in the two entities under the current asymmetrical political setting is not a basin solution either, but a two plant solution based on an outsourcing arrangement. These findings imply that the river basin management approach can not be considered the best management approach for the arid transboundary case at hand, and hence is not unequivocally universally applicable.

Dombrowsky, Ines; Almog, Ram; Becker, Nir; Feitelson, Eran; Klawitter, Simone; Lindemann, Stefan; Mutlak, Natalie

2010-05-01

49

The organic and mineral matter contents in deposits infilling floodplain basins: Holocene alluviation record from the K?odnica and Osob?oga river valleys, southern Poland  

NASA Astrophysics Data System (ADS)

The work examines the timing and environmental conditions of floodplain sedimentation in the valleys of the upland K?odnica and piedmont Osob?oga rivers in the Upper Odra River basin. A distribution of 52 14C-ages shows relatively high floodplain sedimentation at the Late Glacial-Holocene transition, more stable floodplain environments since the Early (in the K?odnica Valley) and Middle Holocene (in the Osob?oga Valley) and a gradual increase in floodplain deposition in the Late Holocene (since < 3.4 kyr BP). Organic matter [OM] and mineral matter [MM] fluctuations were correlated with variables responsible for the activation of erosion (i.e. vegetation changes, human impact and hydrological events) as well as factors affecting the local record of sedimentation (i.e. valley morphology, hydrologic conditions and episodes of local erosion). A clear relationship is shown between an increase in alluviation and climate- or human-induced extension of unforested areas. The deposition of mineral-rich sediments increases rapidly during periods characterized by non-arboreal pollen values exceeding approximately 8% in pollen diagrams. On the other hand, the results obtained do not confirm significant interactions between Holocene changes in forest composition and alluviation. Despite the settlement of agrarian groups, the sedimentary record of human activity in the Osob?oga catchment is very poor during the Neolithic and early Bronze Age. A large-scale alluviation of the Osob?oga and K?odnica valleys was initiated during the settlement of people of the Lusatian culture from the middle Bronze Age and escalated in the early Middle Ages and Modern Times. The deposition of products of soil erosion was limited to between ca. 1.9-1.2 kyr BP, probably due to demographic regression during the Migration Period. Comparison of OM/MM fluctuations with phases of increased fluvial activity does not show a relationship between Holocene wetter phases and catchment sediment yield. Sedimentary episodes in the Upper Odra basin also show a low degree of correlation with the probability density curve of the 14C-ages. The results obtained in the K?odnica and Osob?oga valleys indicate a strong to moderate correlation between the spatial distribution of the study sites and the origin of MM-rich deposits, but a weak correlation between the spatial distribution of the study sites and TOC content. Such a pattern suggests that OM/MM fluctuations relate predominantly to the changes in sediment yield, although morphological conditions have a significant impact on the capture potential of sedimentary basins during phases of alluviation. Additionally, high OM content is not a simple function of an increase in wetness of the sedimentary environment. On the other hand, hydrologically-conditioned hiatuses as well as erosion episodes impoverish the sedimentary record, complicating the consideration on the geochronology of deposits and making it difficult to calculate reliable accumulation rates. However, they do not reduce the value of OM/MM fluctuations as an indicator of alluviation events for a preserved series of sediments.

Wójcicki, K. J.; Marynowski, L.

2012-07-01

50

Regional groundwater-flow model of the Redwall-Muav, Coconino, and alluvial basin aquifer systems of northern and central Arizona  

USGS Publications Warehouse

A numerical flow model (MODFLOW) of the groundwater flow system in the primary aquifers in northern Arizona was developed to simulate interactions between the aquifers, perennial streams, and springs for predevelopment and transient conditions during 1910 through 2005. Simulated aquifers include the Redwall-Muav, Coconino, and basin-fill aquifers. Perennial stream reaches and springs that derive base flow from the aquifers were simulated, including the Colorado River, Little Colorado River, Salt River, Verde River, and perennial reaches of tributary streams. Simulated major springs include Blue Spring, Del Rio Springs, Havasu Springs, Verde River headwater springs, several springs that discharge adjacent to major Verde River tributaries, and many springs that discharge to the Colorado River. Estimates of aquifer hydraulic properties and groundwater budgets were developed from published reports and groundwater-flow models. Spatial extents of aquifers and confining units were developed from geologic data, geophysical models, a groundwater-flow model for the Prescott Active Management Area, drill logs, geologic logs, and geophysical logs. Spatial and temporal distributions of natural recharge were developed by using a water-balance model that estimates recharge from direct infiltration. Additional natural recharge from ephemeral channel infiltration was simulated in alluvial basins. Recharge at wastewater treatment facilities and incidental recharge at agricultural fields and golf courses were also simulated. Estimates of predevelopment rates of groundwater discharge to streams, springs, and evapotranspiration by phreatophytes were derived from previous reports and on the basis of streamflow records at gages. Annual estimates of groundwater withdrawals for agriculture, municipal, industrial, and domestic uses were developed from several sources, including reported withdrawals for nonexempt wells, estimated crop requirements for agricultural wells, and estimated per capita water use for exempt wells. Accuracy of the simulated groundwater-flow system was evaluated by using observational control from water levels in wells, estimates of base flow from streamflow records, and estimates of spring discharge. Major results from the simulations include the importance of variations in recharge rates throughout the study area and recharge along ephemeral and losing stream reaches in alluvial basins. Insights about the groundwater-flow systems in individual basins include the hydrologic influence of geologic structures in some areas and that stream-aquifer interactions along the lower part of the Little Colorado River are an effective control on water level distributions throughout the Little Colorado River Plateau basin. Better information on several aspects of the groundwater flow system are needed to reduce uncertainty of the simulated system. Many areas lack documentation of the response of the groundwater system to changes in withdrawals and recharge. Data needed to define groundwater flow between vertically adjacent water-bearing units is lacking in many areas. Distributions of recharge along losing stream reaches are poorly defined. Extents of aquifers and alluvial lithologies are poorly defined in parts of the Big Chino and Verde Valley sub-basins. Aquifer storage properties are poorly defined throughout most of the study area. Little data exist to define the hydrologic importance of geologic structures such as faults and fractures. Discharge of regional groundwater flow to the Verde River is difficult to identify in the Verde Valley sub-basin because of unknown contributions from deep percolation of excess surface water irrigation.

Pool, D.R.; Blasch, Kyle W.; Callegary, James B.; Leake, Stanley A.; Graser, Leslie F.

2011-01-01

51

Palaeoenvironments and palaeotectonics of the arid to hyperarid intracontinental latest Permian- late Triassic Solway basin (U.K.)  

NASA Astrophysics Data System (ADS)

The late Permian to late Triassic sediments of the Solway Basin consist of an originally flat-lying, laterally persistent and consistent succession of mature, dominantly fine-grained red clastics laid down in part of a very large intracontinental basin. The complete absence of body or trace fossils or palaeosols indicates a very arid (hyperarid) depositional environment for most of the sediments. At the base of the succession, thin regolith breccias and sandstones rest unconformably on basement and early Permian rift clastics. Overlying gypsiferous red silty mudstones, very fine sandstones and thick gypsum were deposited in either a playa lake or in a hypersaline estuary, and their margins. These pass upwards into thick-bedded, multi-storied, fine- to very fine-grained red quartzo-felspathic and sublithic arenites in which even medium sand is rare despite channels with clay pebbles up to 30 cm in diameter. Above, thick trough cross-bedded and parallel laminated fine-grained aeolian sandstones (deposited in extensive barchanoid dune complexes) pass up into very thick, multicoloured mudstones, and gypsum deposited in marginal marine or lacustrine sabkha environments. The latter pass up into marine Lower Jurassic shales and limestones. Thirteen non-marine clastic lithofacies are arranged into five main lithofacies associations whose facies architecture is reconstructed where possible by analysis of large exposures. The five associations can be compared with the desert pavement, arid ephemeral stream, sabkha, saline lake and aeolian sand dune environments of the arid to hyperarid areas of existing intracontinental basins such as Lake Eyre and Lake Chad. The accommodation space in such basins is controlled by gradual tectonic subsidence moderated by large fluctuations in shallow lake extent (caused by climatic change and local variation) and this promotes a large-scale layer-cake stratigraphy as exemplified in the Solway basin. Here, the dominant fine-grained mature sandstones above the local basal reg breccias suggest water-reworking of wind-transported sediment, as in the northern part of the Lake Chad basin. Growth faulting occurs in places in the Solway basin, caused by underlying evaporite movement, but these faults did not significantly affect pre-late Triassic sedimentation and did not expose pre-Permian units above the basal breccias. There is no evidence of post-early Permian rifting anywhere during deposition of the late Permian to middle Triassic British succession although the succession is often interpreted with a rift-basin model. The arid to hyperarid palaeoclimate changed little during deposition of the Solway basin succession, in contrast to Lakes Eyre and Chad: and this is attributed to tectonic and palaeolatitude stability. Unlike the later Mesozoic- Cenozoic, only limited plate movements took place during the Triassic in western Europe, palaeolatitude changed little, and the Solway Basin remained in the northern latitudinal desert belt from early to mid-Triassic times. However, the influence of the early Triassic impoverished biota on environmental interpretations needs further study.

Brookfield, Michael E.

2008-10-01

52

Quality of shallow ground water in alluvial aquifers of the Williamette Basin, Oregon, 1993-95. National water-quality assessment program. Water-resources investigations  

SciTech Connect

The purposes of this report are to describe the quality of shallow ground water in alluvial aquifers of the Willamette Basin and to identify relationships between shallow ground-water quality and various natural and anthropogenic factors. Several natural and anthropogenic factors (soil characteristics, cumulative thickness of clay above open interval of well, surficial geology, and land use) were evaluated because of the potential for these factors to either control or be related to contaminant occurrence and spatial distribution. Spatial distributions of nitrite plus nitrate, phosphorous, pesticides and pesticide degradation products, volatile organic compounds (VOCs), trace elements (primarily arsenic, a trace element of local concern), and radon were evaluated for 1993-95. Ancillary chemical data--nitrite, chloride, tritium (H-3), and dissolved-oxygen (DO) concentrations--also are presented.

Hinkle, S.R.

1997-12-31

53

Shallow subsurface stratigraphy and alluvial architecture of the Kosi and Gandak megafans in the Himalayan foreland basin, India  

NASA Astrophysics Data System (ADS)

The Kosi and the Gandak are two major Himalayan tributaries of the Ganga River in the north Bihar plains India. With a large hinterland in the Nepal Himalaya, both these rivers have generated megafans in the plains over the Quaternary time scale. Both these rivers are known to be highly dynamic and sediment-charged. A few conceptual models and limited field data suggested that these megafans have produced thick sand sheets over Late Quaternary period but these ideas have remained speculative and there is no data on the size and dimension of these sand bodies. This paper attempts to reconstruct the subsurface stratigraphy and alluvial architecture for the upper ~ 100 m of the megafans based on electrical resistivity soundings, borehole data and drill cores. Alluvial architecture of the Kosi megafan shows significant variability from proximal to medial parts of the fan in terms of sediment grain size and layer thicknesses. While the medial part shows ~ 20-30 m thick medium to coarse sand sheets which are laterally stacked, the proximal part of the fan has a dominantly gravel unit below ~ 15 m depth that is underlain and overlain by medium to coarse sand units. Further, the medial fan also shows significant vertical and lateral variability in alluvial stratigraphy. The near-surface (< 20 m depth) deposits from the Kosi megafan have pockets of clay and silt within large amalgamated sand bodies whereas the shallow sub-surface (50-100 m depth) sediments are largely sandy and devoid of clay and silt pockets. Alluvial architecture of the Gandak megafan shows two major lithounits; the upper fan succession has a higher stacking density of smaller sand bodies perhaps reflecting the migratory behavior of the river whereas the lower succession shows narrow but thick sand fills reflecting incised channels. The western part of the Gandak megafan has more abundant sand bodies compared to the eastern side of the river along both transects. There are no significant differences between proximal and medial transects across the Gandak megafan. The absence of gravel deposits in the shallow subsurface of the Gandak megafan may be attributed to the presence of a prominent intermontane valley in the hinterland of the Gandak river which has acted as a 'sediment filter' thereby trapping most of the coarser fraction. On the other hand, the Kosi river exits directly through the mountain front, and therefore, has been able to transport gravels into the plains in pre-historic times. Our study thus suggests significant variability in subsurface stratigraphy of the Kosi and the Gandak megafans even though they are located in similar geographic region. Such differences are attributed to the geomorphic diversity of the mountain exits of these megafans and their sediment transport history.

Sinha, Rajiv; Ahmad, Jawed; Gaurav, Kumar; Morin, Guillaume

2014-03-01

54

Formation of internally drained contractional basins by aridity-limited bedrock incision  

E-print Network

-Altiplano Plateau and the Tibetan Plateau and the Tarim basin. Structurally, these areas are reverse fault bounded basin, Tarim basin, orographic barrier, Tibetan Plateau Citation: Sobel, E. R., G. E. Hilley, and M. R; Horton and DeCelles, 1997; Tapponnier and Molnar, 1979; Tapponnier et al., 2001]. Similarly, the Tarim

Hilley, George

55

Water Resources, Land Exploration and Population Dynamics in Arid Areas - The Case of the Tarim River Basin in Xinjiang of China  

Microsoft Academic Search

Water resources are the root of life and development in arid areas like the Xinjiang Autonomous Region of China. In the Tarim Basin in Xinjiang, one of the driest places in the world, melting glaciers are the exclusive water source. Population growth, in particular in-migration, has greatly changed the ecological conditions of the Tarim River Basin in the past 2,500 years.

Jiang Leiwen; Tong Yufen; Zhao Zhijie; Li Tianhong; Liao Jianhua

2005-01-01

56

The effect of vegetation and beaver dams on geomorphic recovery rates of incised streams in the semi-arid regions of the Columbia River basin, USA  

Microsoft Academic Search

Channel incision is a common occurrence in semi-arid regions of the Columbia River basin and throughout the world, where a fragile balance between climate, vegetation and geology makes channels susceptible to changes in hillslope erosion, stream discharge and sediment yield. Incision is defined as a rapid downcutting and lowering of the stream bed such that it reduces the frequency and

M. Pollock; T. Beechie; C. Jordan

2005-01-01

57

Runoff generation processes during the wet-up phase in a semi-arid basin in Iran  

NASA Astrophysics Data System (ADS)

Understanding the hydrological processes in catchments is important for water resources management, particularly in semi-arid regions of the world. To contribute to this field, dominant runoff generation processes in a semi-arid basin (283 km2) in Southwestern Iran were investigated using analysis of hydrometric data in combination with natural isotopic tracers through the wet-up phase of a rainy season. The analysis of seven rainfall-runoff events during the rainfall dominated period illustrated the role of antecedent base flow and cumulative rainfall for explaining the hydrological response. Three distinct storm events and the corresponding discharge were collected and analyzed for oxygen-18 and deuterium isotope composition. The results show that during the wetting-up cycle, the runoff ratio during storm events increased progressively from 1 to 10%. Higher event runoff ratios following catchment wet-up were shown to be directly linked to changes in soil moisture, which in turn controlled the runoff generation processes. In line with the hydrometric results, the two-component hydrograph separation using ?18O and ?2H demonstrated a clear connection to the antecedent wetness conditions. The results suggest that the runoff ratios during storms and the partitioning of event and pre-event water fractions are sensitive to the amount of catchment wet-up and could hence be strongly impacted by changes in the timing, duration and amount of precipitation in the future.

Zarei, H.; Akhondali, A. M.; Mohammadzadeh, H.; Radmanesh, F.; Laudon, H.

2014-04-01

58

Late Eocene arid climate in Asia inferred from multi-proxy sclerochronology using oyster shells from the Tarim Basin  

NASA Astrophysics Data System (ADS)

The Asian climate is characterized by a strong duality between monsoon dominant climate in southeastern Asia and arid climate in central Asia. Based on climate modelling, this pattern has been explained by two main driving mechanisms associated to the Indo-Asia collision: uplift of Tibetan Plateau and/or retreat of an epicontinental sea formerly covering Asia. However, climate proxies are lacking to test these hypotheses and understand how and when this climate pattern was established. The aim of this study is to develop a new method to understand the Late Eocene climate in central Asia, when the Paratethys was still covering the continent. A crucial task to this end is to reconstruct the climate seasonality in central Asia: when and how the climate changed from a probably temperate climate, due to the sea presence, to an arid climate? Did this climate change have an impact on the monsoon intensification in southestern Asia? Here we use bivalve sclerochronology to assess the Eocene climate variability on seosonal time scales in Central Asia. Well preserved oyster shells (Sokolowia buhsii, Grewingk) were sampled in marine sediments from Lutetian to Bartonian age in southwestern Tarim Basin, Xinjiang, China (Aertashi and Kezi sections). The Paratethys sea was shallow and partially closed, thus the challenge is to distinguish temperature from salinity effects on the biomineralization. Here, we present a new method using multi-proxy approach. The fossils were cut perpendicularly to the maximum growth axis to expose incremental yearly growth lines of the shell to be analysed. We first obtained Mg/Ca record using LA ICP-MS indicative of the temperature variations. We then recovered an isotopic sclerogeochemistry (?18Oc) record using micromilling extraction to assess the ?18Ow (and thereby the salinity) of the sea. Results show that seasonal temperature variability was considerable. Furthemore salinity increase during summers indicating a negative water balance. Thus, we infer that central Asian climate was already very arid during the Late Eocene, although the Paratethys sea was still covering the Asian continent. This is an apparent contradiction with the first assumption of a temperate climate before sea retreat but is in agreement with coeval palynological data from the Tarim Basin and with recent climate models of Eocene Asian monsoons.

Bougeois, Laurie; de Rafélis, Marc; Reichart, Gert-Jan; de Nooijer, Lennart J.; Nicollin, Florence; Dupont-Nivet, Guillaume

2013-04-01

59

Biogeochemical Connectivity in a Semi-Arid River Basin: San Pedro River , Arizona, USA  

NASA Astrophysics Data System (ADS)

Streams and rivers are closely connected to the groundwater that supplies their baseflow, but only episodically connected to the biogeochemically diverse uplands that dominate catchment area. This disconnection with uplands is especially marked in semi-arid systems where full connection of the catchment to the drainage network is infrequent, occurring for only a few days each year. While these hydrologic connections are infrequent, they are critical for supplying the carbon and nitrogen that drive in and near stream biogeochemistry for non-flood periods in these systems. Here we discuss a conceptual model of river scale catchment biogeochemistry for the San Pedro River. An important element of biogeochemical linkages in semi-arid river systems is that dissolved constituents are consumed during transport and thus upland contributions of dissolved materials decrease with travel distance and catchment size. Suspended and particulate export do not decrease with catchment size and thus represent large fluxes of nitrogen and carbon during flood flows in a river system. While some fraction of this suspended load is transported through a system a significant percentage remains in stream bed sediments. This sediment load represents a key resource for biogeochemical processing and nutrient availability during non-flood periods. These resources are mobilized into the aquatic environment through groundwater flux into the surface water system, hyporheic exchange and diurnal ET pumping of the stream bank environment. Floods and the sediment and nutrients fluxes they transport thus represent a hot moment that later drives the hot spot of riparian systems on the landscape.

Meixner, T.; Brooks, P.; Hogan, J.

2008-12-01

60

Paired Catchment Modeling Study for a Monsoon Flood Event in Neighboring Semi-Arid Basins, New Mexico  

NASA Astrophysics Data System (ADS)

Flooding in ephemeral stream networks can significantly impact channel geomorphology, sediment transport, biogeochemical cycles, and water availability for consumptive and recreational use. In order to better understand the spatial patterns of flooding, distributed models may provide an opportunity for further investigation of rainfall-runoff dynamics in headwater semi-arid catchments including flood generation in ungauged portions of a watershed. For example, the Rio Puerco in west-central New Mexico is an ephemeral tributary of the Rio Grande spanning approximately 18,896 km2 with mountainous forests to the north and semi-arid desert to the south. In mid-September 2003, a series of late monsoonal storms traversed the northern extent of watershed resulting in a flood pulse which propagated through the main reach of the catchment and into the Rio Grande thereby substantially influencing streamflow as far south as Elephant Butte Reservoir (289 km). Radar data suggests flooding most likely emanated from two neighboring sub-catchments within the upper reaches of the watershed. In order to better understand the source of significant hydrologic events within the catchment, we utilize a fully distributed model to simulate the flood within the gauged Upper Rio Puerco Watershed (1119 km2) as well as the immediately adjacent but ungauged Torreon Wash (1344 km2). The TIN-Based Real-time Integrated Basin Simulator (tRIBS) prioritizes interactions between the vadose and saturated zone through the simulation of downward moving infiltration fronts and a variable groundwater surface. Topography is captured through a multiple resolution triangular irregular network (TIN) which accurately represents changes in elevation and simultaneously diminishes the model's computational demands. In addition to faithfully modeling topographic features, tRIBS requires accurate representation and calibration of soil, land use features, and geomorphic data. Calibration is performed through a manual procedure in which parameter values are adjusted in an effort to match an observed stream hydrograph with the model output for a series of storm and inter-storm periods. Following model calibration, we transfer the parameter set to the neighboring Torreon Wash. Model results for the paired catchment study demonstrate the appropriateness of parameter transfer between two neighboring semi-arid catchments.

Wyckoff, R. L.; Vivoni, E. R.

2005-12-01

61

Northwest Arid Lands : an introduction to the Columbia Basin shrub-steppe  

SciTech Connect

This book explores the rich variety of life in shrub-steppe lands of the Columbia River Basin. It describes, for a non-technical audience, the flora, fauna, and geology of the lower Columbia Basin in and around the Tri-Cities, Washington. Features include color photos and maps of shrub-steppe plants and animals; lists and illustration of common plants, mammals, reptiles, amphibians, birds, fish, and species of conservation concern; tips on places to see wildflowers and wildlife; geological travel logs from the Tri-Cities to Seattle and Spokane; and a comprehensive bibliography and definition of ecological terms.

O'Connor, Georganne P. (BATTELLE (PACIFIC NW LAB)); Wieda, Karen J. (BATTELLE (PACIFIC NW LAB))

2001-04-15

62

Water resources assessment in the Minqin Basin: an arid inland river basin under intensive irrigation in northwest China  

Microsoft Academic Search

The Minqin Basin is at the lower reach of the Shiyang River of Gansu province in northwest China. Dramatic decline in groundwater\\u000a level has resulted from over-abstraction of groundwater since the late 1950s to satisfy increasing irrigation and other demands.\\u000a Severe water shortage led to environmental degradation. To better understand the spatial–temporal variation of groundwater\\u000a levels and to evaluate the

Yanlin Zhang; Jinhui Ma; Xiaoli Chang; Jan van Wonderen; Lili Yan; Jinhua Han

63

Riparian vegetation of two semi-arid Mediterranean rivers: Basin-scale responses of woody and herbaceous plants to environmental gradients  

Microsoft Academic Search

Mediterranean fluvial ecosystems are subjected to ever-increasing water demands and to a wide variety of other human impacts\\u000a with potential negative effects on riparian vegetation. Nevertheless, few studies have compared the importance of human versus\\u000a natural factors in structuring riparian vegetation in this region, particularly in semi-arid areas. We examined basin-scale\\u000a responses of riparian vegetation to the main environmental gradient

M. Jacoba Salinas; J. Jesús Casas

2007-01-01

64

Late Miocene episodic lakes in the arid Tarim Basin, western China.  

PubMed

The Tibetan Plateau uplift and Cenozoic global cooling are thought to induce enhanced aridification in the Asian interior. Although the onset of Asian desertification is proposed to have started in the earliest Miocene, prevailing desert environment in the Tarim Basin, currently providing much of the Asian eolian dust sources, is only a geologically recent phenomenon. Here we report episodic occurrences of lacustrine environments during the Late Miocene and investigate how the episodic lakes vanished in the basin. Our oxygen isotopic (?(18)O) record demonstrates that before the prevailing desert environment, episodic changes frequently alternating between lacustrine and fluvial-eolian environments can be linked to orbital variations. Wetter lacustrine phases generally corresponded to periods of high eccentricity and possibly high obliquity, and vice versa, suggesting a temperature control on the regional moisture level on orbital timescales. Boron isotopic (?(11)B) and ?(18)O records, together with other geochemical indicators, consistently show that the episodic lakes finally dried up at ?4.9 million years ago (Ma), permanently and irreversibly. Although the episodic occurrences of lakes appear to be linked to orbitally induced global climatic changes, the plateau (Tibetan, Pamir, and Tianshan) uplift was primarily responsible for the final vanishing of the episodic lakes in the Tarim Basin, occurring at a relatively warm, stable climate period. PMID:25368156

Liu, Weiguo; Liu, Zhonghui; An, Zhisheng; Sun, Jimin; Chang, Hong; Wang, Ning; Dong, Jibao; Wang, Huanye

2014-11-18

65

Geochemistry and solute sources of surface waters of the Tarim River Basin in the extreme arid region, NW Tibetan Plateau  

NASA Astrophysics Data System (ADS)

Major ion concentrations of river, lake and snow waters were measured to better understand the water quality, hydrochemical processes and solute sources of surface waters within the Tarim River Basin in the extreme arid region. Surface waters are slightly alkaline and are characterized by high total dissolved solids (TDS). TDS values varies over two orders of magnitude from fresh (76%) to brackish (24%) with a mean value of 1000 mg/L, higher than the global river average and river waters draining the Himalayas and the southeastern Tibetan Plateau. Most of the samples were Ca2+sbnd (Mg2+)sbnd HCO3- type and suited for drinking and irrigation. Water quality of Aksu River (AK), Hotan River (HT) and Northern Rivers (NR) is better than the others. Rock weathering, ion exchange and precipitation are the major hydrogeochemical processes responsible for the solutes in rivers waters. Anthropogenic input to the water chemistry is minor and human activities accelerate increase of river TDS. The quantitative solute sources are first calculated using a forward model in this area. The results show that evaporite dissolution, carbonate weathering, atmospheric input, and silicate weathering contributed 58.3%, 25.7%, 8.7%, and 8.2% of the total dissolved cations for the whole basin. Evaporite dissolution dominated in Lake Waters (LW), HT, Yarkant River (YK), Tarim River (TR), and Southern Rivers (SR), contributing 73.5%, 53.4%, 56.7%, 77%, and 74.2% of the total dissolved cations, respectively. Carbonate weathering dominated in AK and NR, contributing 48% and 44.4% of the total dissolved cations, respectively. The TDS flux of HT, TR, AK, YK was 66.0, 118.6, 134.9, and 170.4 t/km2/yr, respectively, higher than most of the rivers in the world. Knowledge of our research can promote effective management of water resources in this desert environment and add new data to global river database.

Xiao, Jun; Jin, Zhang-Dong; Ding, Hu; Wang, Jin; Zhang, Fei

2012-08-01

66

Tamarix Abundance in Arid River Basins of Arizona (USA) Reflects Prevailing Hydrology  

NASA Astrophysics Data System (ADS)

Flow regimes are strong determinants of riparian vegetation structure. Flow regimes vary among rivers of the American Southwest because of intrinsic hydrogeomorphic differences and because of differing degrees and types of human influence. This study reports on a survey of river reaches in the Gila and Bill Williams drainage basins of Arizona. that varied in flow permanence (perennial, intermittent, ephemeral), presence or absence of an upstream flow-regulating dam, and presence or absence of municipal effluent as a water source. The study focused on abundance patterns of Tamarix ramosissima, a species introduced to North America, relative to those of Populus fremontii and Salix gooddingii, which historically were common pioneer trees in the region. Analysis indicated that Tamarix was significantly more abundant than Populus-Salix at sites with intermittent flow (and thus where groundwater seasonally declined below rooting zones of shallow-rooted phreatophytes) and at sites below flow-regulating dams. Populus-Salix, in contrast, was the dominant forest type along free-flowing, perennial rivers. In reaches with ephemeral flow, including those below diversion dams, all forest types were sparse or absent and xeric shrublands predominated. Riparian ecosystem restoration projects are underway along several rivers in the American Southwest, most of which have a goal of increasing the abundance of Populus-Salix forests. These data affirm the importance of flow regime restoration for re-establishing Populus-Salix as the dominant pioneer forest type.

Stromberg, J. C.

2005-12-01

67

Linkages between snow ablation and atmospheric boundary-layer conditions in a semi-arid basin of Western Canada  

NASA Astrophysics Data System (ADS)

High-elevation snowpacks provide critical inputs to the hydrological system of mountainous semi-arid regions where summer precipitation is insufficient to maintain adequate discharges for ecological and economic needs. The Okanagan Basin in Western Canada is an example of such a system, as most of the summer streamflow is derived from snowmelt. To better understand how snowmelt events vary as a result of atmospheric conditions, this study developed statistical models using upper-air atmospheric data for evaluating changes in snowpack ablation. Specifically, radiosonde data were statistically linked with detailed ground-based measurements of snowmelt and associated streamflow. Statistical models were developed based on data from the 2007 ablation season and concurrent data from the 850 hPa geopotential height. These models explained 57-68% of the variance in snowmelt for 2007, and were extended to predict snowmelt for the radiosonde period of record (1972-2012). Time-series analyses showed significant trends toward higher winter and spring temperatures, vertical temperature gradients in the atmospheric boundary layer in spring, and earlier dates for snowmelt and freshet initiation. Significant negative trends were also found towards decreasing spring precipitation. More broadly, ablation-season climatic and hydrological variables were significantly positively correlated with the winter and spring Multivariate El Niño Southern Oscillation and Pacific Decadal Oscillation indices, in which the positive (negative) phase was associated with higher (lower) magnitude and frequency of melt events. This combination of strong correlations and significant temporal trends indicates that with projected air-temperature increases, the magnitude and duration of melt events are likely to increase, particularly during favourable phases of the above teleconnections.

Jackson, Scott I.; Prowse, Terry D.; Bonsal, Barrie R.

2014-09-01

68

Evaluation of future climate change impacts on semi-arid Cobres basin in southern Portugal  

NASA Astrophysics Data System (ADS)

This study evaluated future climate change impacts on hydrological and sediment transport processes for the medium-sized (705 km2) agriculture dominated Cobres basin, Portugal, in the context of anti-desertification strategies. We used the Spatial-Temporal Neyman-Scott Rectangular Pulses (STNSRP) model—RainSim V3, a rainfall conditioned weather generator—ICAAM-WG, developed in this study but based on the modified Climate Research Unit daily weather generator (CRU-WG), and a PBSD hydrological model—SHETRAN, to downscale projections of change. Climate projections were derived from the RCM HadRM3Q0 output, provided by the ENSEMBLES project, for the SRES A1B scenario for the period 2041-2070. The RainSim V3 and ICAAM-WG models are demonstrated to be able to reproduce observed climatology for the period 1981-2010. The SHETRAN model reproduces hourly runoff with Nash-Sutcliffe Efficiency (NSE) of 0.86 for calibration (2004-2006) and 0.74 for validation (2006-2008) for basin outlet; it reproduces hourly sediment discharge with NSE of 0.48 for the storm from October 23rd 2006 to October 27th 2006. We found that future mean climate is drier, with mean annual rainfall decreased by ~88 mm (19%), mean annual PET increased ~196 mm (16%) and consequent mean annual runoff and sediment yield decreased respectively ~48 mm (50%) and 1.06 t/ha/year (45%). The future mean annual AET decreases ~41 mm (11%), which occurs mainly in spring indicating a more water-limited future climate for vegetation and crop growth. Under current conditions, November to February is the period in which runoff and sediment yield occur frequently; however, it is reduced to December to January in future, with changes in the occurrence rate of ~50%. On the other hand, future wet extremes are more right-skewed. Future annual maximum discharge and sediment discharge decrease for extremes with return periods (T) less than 20 years and the decreases are especially greater for those with T less than 2 years; besides, both quantities present the same or slightly lower magnitudes as those with T larger than 20 years. The annual maximum discharge (sediment discharge) series, under control climate, follows the GEV distribution with location parameter of 64.6 m3/s (164.4 kg/s), scale parameter of 46.5 m3/s (120.3 kg/s) and shape parameter of 0.09 (-0.24); under future climate, the annual maximum discharge series follows the gamma distribution with scale parameter of 75.2 m3/s and shape parameter of 0.97 and the annual maximum sediment discharge series follows the three-parameter lognormal distribution with location parameter of -46.2 kg/s, mean of 5.3 kg/s and standard deviation of 0.78. This study has confirmed the increasing concerns of water scarcity and drought problems in southern Portugal; but it also indicated the mitigation of sediment transport for most of time in the future except heavy events. However, the results should be interpreted carefully since we did not consider possible changes of land-use in the future, as well as the climate and hydrological modelling uncertainties.

Zhang, Rong; Corte-Real, João; Moreira, Madalena; Kilsby, Chris; Burton, Aidan; Blenkinsop, Stephen; Forsythe, Nathan; Nunes, João; Sampaio, Elsa

2014-05-01

69

Alluvial Fans on Mars  

NASA Technical Reports Server (NTRS)

Moore and Howard [1] reported the discovery of large alluvial fans in craters on Mars. Their initial survey from 0-30 S found that these fans clustered in three distinct regions and occurred at around the +1 km MOLA defined Mars datum. However, due to incomplete image coverage, Moore and Howard [1]could not conduct a comprehensive survey. They also recognized, though did not quantitatively address, gravity scaling issues. Here, we briefly discuss the identification of alluvial fans on Mars, then consider the general equations governing the deposition of alluvial fans and hypothesize a method for learning about grain size in alluvial fans on Mars.

Kraal, E. R.; Moore, J. M.; Howard, A. D.; Asphaug, E. A.

2005-01-01

70

Development of a 3D groundwater flow model with scarce data in semi-arid to arid region: the western drainage basin of the Dead Sea (Israel and West Bank)  

NASA Astrophysics Data System (ADS)

Water is scarce in the semi-arid to arid region around the Dead Sea where water supply mostly relies on restricted groundwater resources. Because of population increase the regional groundwater body is exposed to additional stress, which also results in a continuous decrease of the Dead Sea level. As the interdependency between water demand from population increase and the decrease in groundwater availability will proceed over the next years, the stressed water supply situation appears to proceed also and possibly worsens unless sustainable changes are introduced. These changes however, can only be suggested if the hydrogeological situation in the tectonically complex region is fully understood. A number of simplified models of the Judea Group aquifer have been formulated and employed using a two-dimensional (one horizontal layered) numerical simulation of groundwater flow (Baida et al. 1978; Goldschtoff & Shachnai, 1980; Guttman, 2000; Laronne Ben-Itzhak & Gvirtzmann, 2005). However, all previous approaches focused only on a limited area of the Judea Group aquifer. We developed a high resolution regional groundwater flow model for the entire western basin of the Dead Sea. Whereas the structural model could be defined using a large geological dataset, the challenge was to generate the groundwater flow model with only limited well data. With the help of the scientific software OpenGeoSys (OGS) the challenge was reliably solved resulting in a simulation of the hydraulic characteristics (hydraulic conductivity and hydraulic head) of the cretaceous aquifer system, which was calibrated using PEST.

Gräbe, A.; Rink, K.; Fischer, T.; Sun, F.; Rödiger, T.; Kolditz, O.

2012-04-01

71

Holocene dune accumulation in the Youledusi Basin of Tianshan Mt., NW China Response to the westerly-dominated climate in arid central Asia  

NASA Astrophysics Data System (ADS)

Understanding the spatial and temporal patterns of climate change in a given region may provide insights into the underlying climate-forcing mechanisms. In east and south Asia, Asian monsoon variations during the Holocene have been well-documented by precisely dated cave deposits, peat and lake and marine sediments. However, Holocene climate patterns in arid central Asia (ACA) dominated by the Westerlies are poorly documented and understood. Although there have been some published studies on lake cores recording Holocene moisture evolution in the ACA, we still know little about the climate evolutionary patterns and mechanisms that drive the westerlies. In the arid areas aeolian dunes are often regarded as indicators of past aridity, and the development of palaeosol implicates relatively wet condition. This study will first provide the chronostratigraphy of a set of palaeodunes in the Youledusi Basin (ca. 2400 m above sea level) of Tianshan Mt., NW China. Systematic optically stimulated luminescence dating (ca. 60 samples) of multiple sites (eight sections) is used together with stratigraphic analysis in order to reconstruct the evolution of the sand dunes, which is able to infer the history of Holocene moisture variation.

Long, Hao; Shen, Ji; Frechen, Manfred; Chen, Jianhui; Yang, Linhai

2013-04-01

72

Understanding hydrologic budgets, dynamics in an arid basin and explore spatial scaling properties using Process-based Adaptive Watershed Simulator (PAWS)  

NASA Astrophysics Data System (ADS)

The Southern California hot desert hosts a fragile ecosystem as well as a range of human economic activities, primarily mining, energy production and recreation. This inland arid landscape is characterized by occasional intensive precipitation events and year-round strong potential evapotranspiration. In this landscape, water and especially groundwater is vital for ecosystem functions and human use. However, the impact of recent development on the sustainability of groundwater resources in the area has not been thoroughly investigated. We apply an integrated, physically-based hydrologic-land surface model, the Process-based Adaptive Watershed Simulator + Community Land Model (PAWS+CLM) to evaluate the sustainability of the groundwater resources in the area. We elucidate the spatio-temporal patterns of hydrologic fluxes and budgets. The modeling results indicate that mountain front recharge is the essential recharging mechanism for the alluvial aquifer. Although pumping activities do not exceed annual-average recharge values, they are still expected to contribute significantly to groundwater drawdown in business-as-usual scenario. The impact of groundwater withdrawals is significant on the desert ecosystem. The relative importance of groundwater flow on NPP rises significantly as compared to other ecosystems. We further evaluate the fractal scaling properties of soil moisture in this very arid system and found the relationship to be much more static in time than that found in a humid continental climate system. The scaling exponents can be predicted using simple functions of the mean. Therefore, multi-scale model based on coarse-resolution surrogate model is expected to perform well in this system. The modeling result is also important for assessing the groundwater sustainability and impact of human activities in the desert environment.

Fang, K.; Shen, C.; Salve, R.

2013-12-01

73

Geomorphology and morphometric characteristics of alluvial fans, Guadalupe Mountains National Park and adjacent areas, west Texas and New Mexico  

E-print Network

analysis indicate that the morphometric relationships that exist between the alluvial fans of the GMR and their contributory drainage basins are comparably to those of alluvial fans of the western United States. Morphologic and morphometric differences...

Given, Jeffrey Lyle

2004-09-30

74

[Influence of soil salinization on soil animal community in an arid oasis of middle Heihe River basin].  

PubMed

An investigation was conducted on the status of soil salinization and the structure of soil animal community across six land use/cover types in an arid oasis of middle Heihe River basin, and the methods of redundancy analysis, regression analysis, and path analysis were adopted to analyze the responses of the soil animal community under different land use/cover types and different management modes to the various status of soil salinization. The six land use/cover types were 21-year old shrub land without irrigation and fertilization, 28-year old poplar and 33-year-old pine plantations with irrigation, 27- and 100-year-old farmlands with irrigation and fertilization, and natural grassland, from which all the other five land use/cover types were converted. The results demonstrated that land cover change in the absence of management practices did not lead to a significant change in the abundance and group richness of the soil animal community, while land cover change in the presence of management practices resulted in a significant change in the soil animal community. The evolvement of the soil animal community structure was co-affected by soil pH, soluble salt content, and Na+, Cl, HCO3-, and Mg2+ concentrations, among which, soil soluble salt and Na had the greatest contribution, being the key affecting factors. The abundance and group richness of the soil animal community had significant negative exponential correlations with soil soluble salt content and Na+ concentration, and significant quadratic correlations with soil Mg2+ and HCO3- concentrations. The calculated ecological threshold values of soil Mg2+ and HCO3- concentrations for the abundance and group richness of the soil animal community were 38.7-39.4 mg x kg(-1) and 324.9-335.3 mg x kg(-1), at which, the abundance and group richness reached their peaks 40-43 individuals x m(-2) and 13-14 families x m(-2), respectively. When the Mg2+ and HCO3- concentrations increased further, the abundance and group richness decreased. PMID:22937643

Liu, Ji-Liang; Li, Feng-Rui; Niu, Rui-Xue; Liu, Chang-An; Liu, Qi-Jun

2012-06-01

75

Using a physically-based model, tRIBS-Erosion, for investigating the effects of climate change in semi-arid headwater basins.  

NASA Astrophysics Data System (ADS)

Soil erosion due to rainfall detachment and flow entrainment of soil particles is a physical process responsible for a continuous evolution of landscapes. The rate and spatial distribution of this phenomenon depend on several factors such as climate, hydrologic regime, geomorphic characteristics, and vegetation of a basin. Many studies have demonstrated that climate-erosion linkage in particular influences basin sediment yield and landscape morphology. Although soil erosion rates are expected to change in response to climate, these changes can be highly non-linear and thus require mechanistic understanding of underlying causes. In this study, an integrated geomorphic component of the physically-based, spatially distributed hydrological model, tRIBS, the TIN-based Real-time Integrated Basin Simulator, is used to analyze the sensitivity of semi-arid headwater basins to climate change. Downscaled outputs of global circulation models are used to inform a stochastic weather generator that produces an ensemble of climate scenarios for an area in the Southwest U.S. The ensemble is used as input to the integrated model that is applied to different headwater basins of the Walnut Gulch Experimental Watershed to understand basin response to climate change in terms of runoff and sediment yield. Through a model application to multiple catchments, a scaling relationship between specific sediment yield and drainage basin area is also addressed and probabilistic inferences on future changes in catchment runoff and yield are drawn. Geomorphological differences among catchments do not influence specific changes in runoff and sediment transport that are mostly determined by precipitation changes. Despite a large uncertainty dictated by climate change projections and stochastic variability, sediment transport is predicted to decrease despite a non-negligible possibility of larger runoff rates.

Francipane, Antonio; Fatichi, Simone; Ivanov, Valeriy Y.; Noto, Leonardo V.

2013-04-01

76

Isotopic evidence for climatic influence on alluvial-fan development in Death Valley, California  

SciTech Connect

At least three semiarid to arid cycles are recorded by ..delta../sup 13/C values of organic matter in layers of rock varnishes on surfaces of Hanaupah Canyon and Johnson Canyon alluvial fans, Death Valley, California. These isotopic paleoenvironmental signals are interpreted as indicating major periods of fan aggradation during relatively more humid periods and fan entrenchment during subsequent lengthy arid periods.

Dorn, R.I.; DeNiro, M.J.; Ajie, H.O.

1987-02-01

77

Soil–water conservation and rainwater harvesting strategies in the semi-arid Mzingwane Catchment, Limpopo Basin, Zimbabwe  

Microsoft Academic Search

Various soil water management practices have been developed and promoted for the semi arid areas of Zimbabwe. These include a variety of infield crop management practices that range from primary and seconday tillage approaches for crop establishment and weed management through to land forming practices such as tied ridges and land fallowing. Tillage methods evaluated in this study include deep

Walter Mupangwa; David Love; Steve Twomlow

2006-01-01

78

Temporal correlation of fluvial and alluvial sequences in the Makran Range, SE-Iran  

NASA Astrophysics Data System (ADS)

The Makran region of southeastern Iran is an active accretionary wedge with a partially subaerial component. New investigations have revealed a rather complex geodynamic evolution of the Makran active accretionary wedge that is not yet fully understood in its entity. Ongoing convergence between the Arabian and Eurasian plates and tectonic activity since the late Mesozoic has extended all trough the Quaternary. We focus here on fluvial and alluvial sequences in tectonically separated basins that have been deposited probably in the Pliocene/Quaternary, based on stratigraphic classification in official geological maps, in order to understand the climatic and tectonic forces occurring during the ongoing accretionary wegde formation. Specifically, we investigate the influence of Quaternary climate variations (Pleistocene cold period, monsoonal variations) on erosional and depositional processes in the (semi)arid Makran as well as local and regional tectonic forces in the Coastal and Central Makran Range region. Necessary for such an analysis is a temporal calibration of alluvial and fluvial terrace sequences that will allow an inter-basin correlation. We utilize the exposure age dating method using terrestrial cosmogenic nuclides (TCN) due to the lack of otherwise datatable material in the arid Makran region. Limited radiocarbon data are only available for marine terraces (wave-cut platforms). Our preliminary 21Ne and 10Be TCN-ages of amalgamated clast samples from (un)deformed terrace and alluvial sequences range from ~250 ky to present day (modern wash). These ages agree in relative terms with sequences previously assigned by other investigations through correlation of Quaternary sequences from Central and Western Iran regions. However, our minimum ages suggest that all age sequences are of middle to late Pleistocene age, compared to Pliocene age estimates previously assigned for the oldest units. Although often suggested, a genetical relation and connection of those fluvial sequences to coastal terraces and wave-cut platforms is problematic due to ambiguous ages and obscured stratigraphic linkage. Our data suggest that events of terrace formation are roughly coeval between basins, but do not indicate a distinct climate forcing, though there is some tendency that terraces were formed during interglacial periods. Preliminary incision rates derived from strath terraces are on the order of 0.1-3 mm/yr with non-steady intervals. This in turn is well in the range of uplift rates deduced from coastal terraces. Further investigations are on the way, especially resolving complex exposure histories based on combining cosmogenic radionuclides and 21Ne.

Kober, F.; Zeilinger, G.; Ivy-Ochs, S.; Dolati, A.; Smit, J.; Burg, J.-P.; Bahroudi, A.; Kubik, P. W.; Baur, H.; Wieler, R.; Haghipour, N.

2009-04-01

79

The characteristics of ground-water resources and their changes under the impacts of human activity in the arid Northwest China—a case study of the Shiyang River Basin  

Microsoft Academic Search

Based on a hydrogeological survey and geochemical and isotopic technology, a case study of the Shiyang River Basin is presented to illustrate ground-water resources and geochemistry and their changes caused by the impact of human activity in the arid area of Northwest China. The aquifer is mainly recharged by surface water originating in mountain regions, and there is extensive transfer

J. Z. Ma; X. S. Wang; W. M. Edmunds

2005-01-01

80

The effect of vegetation and beaver dams on geomorphic recovery rates of incised streams in the semi-arid regions of the Columbia River basin, USA.  

NASA Astrophysics Data System (ADS)

Channel incision is a common occurrence in semi-arid regions of the Columbia River basin and throughout the world, where a fragile balance between climate, vegetation and geology makes channels susceptible to changes in hillslope erosion, stream discharge and sediment yield. Incision is defined as a rapid downcutting and lowering of the stream bed such that it reduces the frequency and duration of flooding onto the adjacent floodplain. We are studying the feasibility of restoring incised streams throughout the interior Columbia River basin. We hypothesize that under proper land use management, it is possible for them to aggrade such that they reconnect to their former floodplains within relatively short time frames. Theoretical and empirical evidence suggests that over decadal time scales, changes to land management that excludes grazing and allows riparian vegetation to become established can cause significant fill within the incised valleys. Preliminary modeling suggests that factors most affecting the length of time for an incised valley to completely aggrade and reconnect to its pre-incision floodplain are the depth of the incision, sediment production in the watershed, the amount and type of riparian vegetation, and the extent of beaver dam construction. While most natural resource and fisheries managers are aware of widespread incision throughout the Columbia River basin, the extent of incision within the range of the Pacific salmon is largely undocumented. However, we do know many incised streams that historically supported salmon no longer do so, and that habitat conditions are severely degraded in these incised streams. The historical record shows that numerous salmon-bearing streams in the semi-arid region of the interior Columbia River basin once contained narrow and deep, slowly meandering channels lined with cottonwoods, willows and/or sedges, contained numerous beaver dams, contained abundant and easily accessible off-channel habitat on the floodplain and had good flow and cool temperatures throughout most of the year. Today most of these streams are incised and contain little or no riparian vegetation or beaver dams. Stream temperatures are high and flow is ephemeral. Incision is thought to have lowered stream-adjacent water tables, causing both the loss of riparian vegetation and the increase in stream temperature. Many of these streams no longer support fish populations. We hypothesize that if incised streams were restored by creating conditions such that they could aggrade and reconnect to their former floodplains, that habitat conditions would be sufficient to again support salmon populations, and that this would greatly expand their range throughout much of the Columbia River basin.

Pollock, M.; Beechie, T.; Jordan, C.

2005-05-01

81

A groundwater-based, objective-heuristic parameter optimisation method for a precipitation-runoff model and its application to a semi-arid basin  

NASA Astrophysics Data System (ADS)

A hydrologic model calibration methodology that is based on groundwater data is developed and implemented using the US Geological Survey's precipitation-runoff modelling system (PRMS) and the modular modelling system (MMS), which performs automatic calibration of parameters. The developed methodology was tested in the Akrotiri basin, Cyprus. The necessity for the groundwater-based model calibration, rather than a typical runoff-based one, arose from the very intermittent character of the runoff in the Akrotiri basin, a case often met in semi-arid regions. Introducing a datum and converting groundwater storage to head made the observable groundwater level the calibration indicator. The modelling of the Akrotiri basin leads us to conclude that groundwater level is a useful indicator for hydrological model calibration that can be potentially used in other similar situations in the absence of river flow measurements. However, the option of an automatic calibration of the complex hydrologic model PRMS by MMS did not ensure a good outcome. On the other hand, automatic optimisation, combined with heuristic expert intervention, enabled achievement of good calibration and constitutes a valuable means for saving effort and improving modelling performance. To this end, results must be scrutinised, melding the viewpoint of physical sense with mathematical efficiency criteria. Thus optimised, PRMS achieved a low simulation error, good reproduction of the historic trend of the aquifer water level evolution and reasonable physical behaviour (good hydrologic balance, Reasonable match of aquifer level evolution, good estimation of mean natural recharge rate).

Mazi, K.; Koussis, A. D.; Restrepo, P. J.; Koutsoyiannis, D.

2004-05-01

82

Evaluation of oasis ecosystem risk by reliability theory in an arid area: a case study in the Shiyang River Basin, China.  

PubMed

Ecosystem risk is a new concept in understanding environmental problems. It is important to study and develop quantitative methods for regional ecosystem risk analysis. In this study, some new indicators and methods for measuring oasis ecosystem risk were established using reliability theory. These indicators are linked to water resource, which is the key restricting factor in arid area oasis ecosystems. They have clear meanings and can also be compared in different arid area oases. A case study in the Liangzhou oasis of the Shiyang River Basin in China shows how to calculate these ecosystem risk indicators. The results of the case study are as follows: the reliability indicator, risk indicator, stability indicator, and integrated loss indicator of the Liangzhou oasis are 0.686, 0.314, 0.743, and 0.301, respectively. This means that the reliability degree of the oasis's ecosystem safety is 68.6%; the degree of risk that it is unsafe is 31.4%; the stability degree is 74.3%; and 30.1% of the oasis's area is supported by over-exploiting underground water and damaging the lower reaches of the ecosystem. This result can be used as a guide in controlling and managing ecosystem risk in the research area. PMID:17915717

Li, Wei-de; Li, Zi-zhen; Wang, Ji-quan

2007-01-01

83

Bedload transport in alluvial channels  

USGS Publications Warehouse

Hydraulic, sediment, land-use, and rock-erosivity data of 22 alluvial streams were used to evaluate conditions of bedload transport and the performance of selected bedload-transport equations. Transport categories of transport-limited (TL), partially transport-limited (PTL), and supply-limited (SL) were identified by a semiquantitative approach that considers hydraulic constraints on sediment movement and the processes that control sediment availability at the basin scale. Equations by Parker et al. in 1982, Schoklitsch in 1962, and Meyer-Peter and Muller in 1948 adequately predicted sediment transport in channels with TL condition, whereas the equations of Bagnold in 1980, and Schoklitsch, in 1962, performed well for PTL and SL conditions. Overall, the equation of Schoklitsch predicted well the measured bedload data for eight of 22 streams, and the Bagnold equation predicted the measured data in seven streams.

Bravo-Espinosa, M.; Osterkamp, W.R.; Lopes, V.L.

2003-01-01

84

Assessment of the hydrogeochemistry and groundwater quality of the Tarim River Basin in an extreme arid region, NW China.  

PubMed

The concentrations of the major and trace elements in the groundwater of the Tarim River Basin (TRB), the largest inland river basin of China, were analyzed before and during rainy seasons to determine the hydrogeochemistry and to assess the groundwater quality for irrigation and drinking purposes. The groundwater within the TRB was slightly alkaline and characterized by high ionic concentrations. The groundwater in the northern sub-basin was fresh water with a Ca(2+)-HCO3(-) water type, whereas the groundwater in the southern and central sub-basins was brackish with a Na(+)-Cl(-) water type. Evaporite dissolution and carbonate weathering were the primary and secondary sources of solutes in the groundwater within the basin, whereas silicate weathering played a minor role. The sodium adsorption ratio (SAR), water quality index (WQI), and sodium percentage (%Na) indicated that the groundwater in the northern sub-basin was suitable for irrigation and drinking, but that in the southern and central sub-basins was not suitable. The groundwater quality was slightly better in the wet season than in the dry season. The groundwater could be used for drinking after treatment for B(3+), F(-), and SO4(2-) and for irrigation after control of the sodium and salinity hazards. Considering the high corrosivity ratio of the groundwater in this area, noncorrosive pipes should be used for the groundwater supply. For sustainable development, integrated management of the surface water and the groundwater is needed in the future. PMID:24221557

Xiao, Jun; Jin, Zhangdong; Wang, Jin

2014-01-01

85

Assessment of the Hydrogeochemistry and Groundwater Quality of the Tarim River Basin in an Extreme Arid Region, NW China  

NASA Astrophysics Data System (ADS)

The concentrations of the major and trace elements in the groundwater of the Tarim River Basin (TRB), the largest inland river basin of China, were analyzed before and during rainy seasons to determine the hydrogeochemistry and to assess the groundwater quality for irrigation and drinking purposes. The groundwater within the TRB was slightly alkaline and characterized by high ionic concentrations. The groundwater in the northern sub-basin was fresh water with a Ca2+-HCO3 - water type, whereas the groundwater in the southern and central sub-basins was brackish with a Na+-Cl- water type. Evaporite dissolution and carbonate weathering were the primary and secondary sources of solutes in the groundwater within the basin, whereas silicate weathering played a minor role. The sodium adsorption ratio (SAR), water quality index (WQI), and sodium percentage (%Na) indicated that the groundwater in the northern sub-basin was suitable for irrigation and drinking, but that in the southern and central sub-basins was not suitable. The groundwater quality was slightly better in the wet season than in the dry season. The groundwater could be used for drinking after treatment for B3+, F-, and SO4 2- and for irrigation after control of the sodium and salinity hazards. Considering the high corrosivity ratio of the groundwater in this area, noncorrosive pipes should be used for the groundwater supply. For sustainable development, integrated management of the surface water and the groundwater is needed in the future.

Xiao, Jun; Jin, Zhangdong; Wang, Jin

2014-01-01

86

Holocene fire occurrence and alluvial responses at the leading edge of pinyon-juniper migration in the Northern Great Basin, USA  

NASA Astrophysics Data System (ADS)

Fire and vegetation records at the City of Rocks National Reserve (CIRO), south-central Idaho, display the interaction of changing climate, fire and vegetation along the migrating front of single-leaf pinyon (Pinus monophylla) and Utah juniper (Juniperus osteosperma). Radiocarbon dating of alluvial charcoal reconstructed local fire occurrence and geomorphic response, and fossil woodrat (Neotoma) middens revealed pinyon and juniper arrivals. Fire peaks occurred ~ 10,700-9500, 7200-6700, 2400-2000, 850-700, and 550-400 cal yr BP, whereas ~ 9500-7200, 6700-4700 and ~ 1500-1000 cal yr BP are fire-free. Wetter climates and denser vegetation fueled episodic fires and debris flows during the early and late Holocene, whereas drier climates and reduced vegetation caused frequent sheetflooding during the mid-Holocene. Increased fires during the wetter and more variable late Holocene suggest variable climate and adequate fuels augment fires at CIRO. Utah juniper and single-leaf pinyon colonized CIRO by 3800 and 2800 cal yr BP, respectively, though pinyon did not expand broadly until ~ 700 cal yr BP. Increased fire-related deposition coincided with regional droughts and pinyon infilling ~ 850-700 and 550-400 cal yr BP. Early and late Holocene vegetation change probably played a major role in accelerated fire activity, which may be sustained into the future due to pinyon-juniper densification and cheatgrass invasion.

Weppner, Kerrie N.; Pierce, Jennifer L.; Betancourt, Julio L.

2013-09-01

87

Responses of Surface Runoff to Climate Change and Human Activities in the Arid Region of Central Asia: A Case Study in the Tarim River Basin, China  

NASA Astrophysics Data System (ADS)

Based on hydrological and climatic data and land use/cover change data covering the period from 1957 to 2009, this paper investigates the hydrological responses to climate change and to human activities in the arid Tarim River basin (TRB). The results show that the surface runoff of three headstreams (Aksu River, Yarkant River and Hotan River) of the Tarim River exhibited a significant increasing trend since 1960s and entered an even higher-runoff stage in 1994. In the contrary, the surface runoff of Tarim mainstream displayed a persistent decreasing trend since 1960s. The increasing trend of surface runoff in the headstreams can be attributed to the combined effects of both temperature and precipitation changes during the past five decades. But, the decreasing trend of surface runoff in the mainstream and the observed alterations of the temporal and spatial distribution patterns were mainly due to the adverse impacts of human activities. Specifically, increasingly intensified water consumption for irrigation and the associated massive constructions of water conservancy projects were responsible for the decreasing trend of runoff in the mainstream. And, the decreasing trend has been severely jeopardizing the ecological security in the lower reaches. It is now unequivocally clear that water-use conflicts among different sectors and water-use competitions between upper and lower reaches are approaching to dangerous levels in TRB that is thus crying for implementing an integrated river basin management scheme.

Xu, Changchun; Chen, Yaning; Chen, Yapeng; Zhao, Ruifeng; Ding, Hui

2013-04-01

88

Responses of surface runoff to climate change and human activities in the arid region of central Asia: a case study in the Tarim River basin, China.  

PubMed

Based on hydrological and climatic data and land use/cover change data covering the period from 1957 to 2009, this paper investigates the hydrological responses to climate change and to human activities in the arid Tarim River basin (TRB). The results show that the surface runoff of three headstreams (Aksu River, Yarkant River and Hotan River) of the Tarim River exhibited a significant increasing trend since 1960s and entered an even higher-runoff stage in 1994. In the contrary, the surface runoff of Tarim mainstream displayed a persistent decreasing trend since 1960s. The increasing trend of surface runoff in the headstreams can be attributed to the combined effects of both temperature and precipitation changes during the past five decades. But, the decreasing trend of surface runoff in the mainstream and the observed alterations of the temporal and spatial distribution patterns were mainly due to the adverse impacts of human activities. Specifically, increasingly intensified water consumption for irrigation and the associated massive constructions of water conservancy projects were responsible for the decreasing trend of runoff in the mainstream. And, the decreasing trend has been severely jeopardizing the ecological security in the lower reaches. It is now unequivocally clear that water-use conflicts among different sectors and water-use competitions between upper and lower reaches are approaching to dangerous levels in TRB that is thus crying for implementing an integrated river basin management scheme. PMID:23377191

Xu, Changchun; Chen, Yaning; Chen, Yapeng; Zhao, Ruifeng; Ding, Hui

2013-04-01

89

Tectonic and climatic control on geomorphological and sedimentary evolution of the Mercure basin, southern Apennines, Italy  

NASA Astrophysics Data System (ADS)

The morpho-tectonic and sedimentary evolution of the Mercure intramontane basin (Calabria-Lucania boundary, southern Apennines) has been assessed through facies analysis, morphostratigraphy and geomorphological correlation with adjacent areas. The Mercure basin, one of the most active seismogenic zones of the southern Apennines, is a favorable area for reconstructing the main stages of landscape evolution of the axial zone because of its capability to record changes in base level during the Quaternary. In addition, the presence of both erosional and depositional Palaeosurfaces is a useful marker for reconstructing tectonic and morphogenetic events, and hence to detect the role played by tectonics and climate in its genesis, evolution and extinction. The present study identifies the key role of tectonics and denudation, combined with high-frequency floods, as mechanisms controlling alluvial sedimentation in the study area. During endorheic conditions, denudational processes driven by pulses of extensional deformation of the basin margin caused strong alluvial inputs that resulted in the development of alluvial fans. Alluvial facies are mainly characterized by turbulent, subaerial, hyperconcentrated flood flows deposited during the glacial, semi-arid conditions of MIS 14. The retrogradational stacking pattern of the alluvial system indicates decreasing rates of tectonic activity along with declining river gradients. The Mercure coalescing alluvial fans were inundated by lake transgression during MIS 13 in response to (i) abrupt tectonic subsidence at the basin margins and (ii) large decrease of coarse sediment supply due to the interplay among climate, tectonics and catchment size changes. In this regard, it is suggested that tectonic control on the drainage network along with climate and long-term slope evolution may have caused marked pulses in sediment supply, thus influencing the arrangement of facies associations in the sedimentary succession. In addition, the study points out that the main tectonic landforms developed during each period of the landscape evolution well correspond with some active fault segments.

Robustelli, Gaetano; Ermolli, Elda Russo; Petrosino, Paola; Jicha, Brian; Sardella, Raffaele; Donato, Paola

2014-06-01

90

A 30000 year record of vegetation dynamics at a semi-arid locale in the Great Basin  

Microsoft Academic Search

Plant macrofossils extracted from fossil woodrat (Neotoma spp.) middens at a single locale in the northwestern Great Basin were used to examine vegetation dynamics during the last 30 000 yr. Although the modem assemblage of xeric species at the study site is a recent occurrence, a large propor- tion of the modem plant taxa near the study locale were also

Robert S. Nowak

91

Attribution of satellite-observed vegetation trends in a hyper-arid region of the Heihe River basin, Western China  

NASA Astrophysics Data System (ADS)

Terrestrial vegetation dynamics are closely influenced by both climate and by both climate and by land use and/or land cover change (LULCC) caused by human activities. Both can change over time in a monotonic way and it can be difficult to separate the effects of climate change from LULCC on vegetation. Here we attempt to attribute trends in the fractional green vegetation cover to climate variability and to human activity in Ejina Region, a hyper-arid landlocked region in northwest China. This region is dominated by extensive deserts with relatively small areas of irrigation located along the major water courses as is typical throughout much of Central Asia. Variations of fractional vegetation cover from 2000 to 2012 were determined using Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation index data with 250 m spatial resolution over 16-day intervals. We found that the fractional vegetation cover in this hyper-arid region is very low but that the mean growing season vegetation cover has increased from 3.4% in 2000 to 4.5% in 2012. The largest contribution to the overall greening was due to changes in green vegetation cover of the extensive desert areas with a smaller contribution due to changes in the area of irrigated land. Comprehensive analysis with different precipitation data sources found that the greening of the desert was associated with increases in regional precipitation. We further report that the area of land irrigated each year can be predicted using the runoff gauged 1 year earlier. Taken together, water availability both from precipitation in the desert and runoff inflow for the irrigation agricultural lands can explain at least 52% of the total variance in regional vegetation cover from 2000 to 2010. The results demonstrate that it is possible to separate the satellite-observed changes in green vegetation cover into components due to climate and human modifications. Such results inform management on the implications for water allocation between oases in the middle and lower reaches and for water management in the Ejina oasis.

Wang, Y.; Roderick, M. L.; Shen, Y.; Sun, F.

2014-09-01

92

Calibration and application of a distributed land surface model for a semi-arid basin using remotely sensed data  

Microsoft Academic Search

A meso-scale medium-resolution land surface model using the NCEP's NOAH code has been setup over the San Pedro basin in Arizona. The model is driven using the 50-year hydrologically balanced land surface data set developed at the University of Washington. To explore the sensitivity of simulation results and model performance to the introduction of remote sensing information, the observed forcings

S. Yatheendradas; L. Bastidas; H. Gupta; S. Sorooshian

2003-01-01

93

Stable isotopes of lake and fluid inclusion brines, Dabusun Lake, Qaidam Basin, western China: Hydrology and paleoclimatology in arid environments  

Microsoft Academic Search

The Qaidam Basin, underlain by salt, is the largest (120,000 km2) on the Qinghai-Tibet Plateau, western China. Numerous shallow to ephemeral saline lakes and dry saline pans are present on the Qarhan Salt Plain. Dabusun Lake, the largest (about 200 km2), contains high salinity Na?Mg?Cl brines. Whereas it precipitates halite, it is fringed by a potash salt flat.The dominant inflow

Wenbo Yang; Ronald J. Spencer; H. Roy Krouse; Tim K. Lowenstein; E. Casas

1995-01-01

94

Nuclear-waste isolation in the unsaturated zone of arid regions  

SciTech Connect

The vadose zone in arid regions is considered as a possible environment for geologic isolation of nuclear waste. There are several topographic and lithologic combinations in the vadose zone of arid regions that may lend themselves to waste isolation considerations. In some cases, topographic highs such as mesas and interbasin ranges - comprised of several rock types, may contain essentially dry or partially saturated conditions favorable for isolation. The adjacent basins, especially in the far western and southwestern US, may have no surface or subsurface hydrologic connections with systems ultimately leading to the ocean. Some rock types may have the favorable characteristics of very low permeability and contain appropriate minerals for the strong chemical retardation of radionuclides. Environments exhibiting these hydrologic and geochemical attributes are the areas underlain by tuffaceous rocks, relatively common in the Basin and Range geomorphic province. Adjacent valley areas, where tuffaceous debris makes up a significant component of valley fill alluvium, may also contain thick zones of unsaturated material, and as such also lend themselves to strong consideration as respository environments. This paper summarizes the aspects of nuclear waste isolation in unsaturated regimes in alluvial-filled valleys and tuffaceous rocks of the Basin and Range province.

Wollenberg, H.A.; Wang, J.S.Y.; Korbin, G.

1982-05-01

95

Palaeoenvironmental reconstruction of a middle Miocene alluvial fan to cyclic shallow lacustrine depositional system  

E-print Network

sandstone and mudstone, the latter exhibiting incipient pedogenic features; (2) distal alluvial fan facies. The development of the basin was constrained by gradual alluvial fan aggradation. Additional support a clear trend of d18 O Sedimentology (2003) 50, 211­236 � 2003 International Association

Utrecht, Universiteit

96

The lower Mzingwane alluvial aquifer: managed releases, groundwater - surface water interactions and the challenge of salinity  

Microsoft Academic Search

The alluvial aquifers of the Mzingwane Catchments are the most extensive of any tributaries in the Limpopo Basin and are present in the lower reaches of most of the larger rivers. The alluvial aquifers form ribbon shapes covering over 20 km in length, generally less than 1 km in width and areal extents ranging from 100 ha to 255 ha

David Love; Richard Owen; Stefan Uhlenbrook; Pieter van der Zaag; William Moyce

2007-01-01

97

[Dynamic tendency of arid oasis under the influence of water resources decrease--a case study of Ejina oasis in Heihe River Basin].  

PubMed

The runoff changes of arid inland river seriously influenced on the formations and changes of oasis in the lower reach. By the oasis patches dynamic modeling, the vegetation-water interrelated analysis, and the estimation of water demand by the ecological system, the dynamic tendency of the Ejina oasis in the lower reach of Heihe River Basin under difference water resources allocating were studied. The results showed that the lowest water demanded for preserving the present oasis area was about 5.7 x 10(8) m3 based on rational usage of the water resources. Considering the water demand of people and livestock, and the water lose in the water transport process, the incoming runoff through the Langxinshan section should be about 6.0 x 10(8) m3 to preserve the present oasis area before 2015. To regain the oasis area to the level at the primary of 1980s, the demand incoming runoff should be about 8.9 x 10(8) m3, and the runoff through the Zhengyixia section should be 10.9 x 10(8)-13.1 x 10(8) m3. PMID:12181897

Wang, Genxu; Cheng, Guodong; Shen, Yongping

2002-05-01

98

Isotopes in the Hueco Bolson aquifer, Texas (USA) and Chihuahua (Mexico): local and general implications for recharge sources in alluvial basins  

NASA Astrophysics Data System (ADS)

Stable isotope data for the Hueco Bolson aquifer (Texas, USA and Chihuahua, Mexico) distinguish four water types. Two types relate to recharge from the Rio Grande: pre-dam (pre-1916) river water with oxygen-18 and deuterium (?18O, ?D, ‰) from (-11.9, -90) to (-10.1, -82), contrasts with present-day river water (-8.5, -74) to (-5.3, -56). Pre-dam water is found beneath the Rio Grande floodplain and Ciudad Juárez, and is mixed with post-dam river water beneath the floodplain. Two other types relate to recharge of local precipitation; evidence of temporal change of precipitation isotopes is present in both types. Recharge from the Franklin and Organ Mountains plots between (-10.9, -76) and (-8.5, -60) on the global meteoric water line (GMWL), and is found along the western side of the Hueco Bolson, north of the Rio Grande. Recharge from the Diablo Plateau plots on an evaporation trend originating on the GMWL near (-8.5, -58). This water is found in the southeastern Hueco Bolson, north of the river; evaporation may be related to slow recharge through fine-grained sediment. Pre-dam water, recognizable by isotope composition, provides information on groundwater residence times in this and other dammed river basins.

Eastoe, Christopher J.; Hibbs, Barry J.; Olivas, Alfredo Granados; Hogan, James F.; Hawley, John; Hutchison, William R.

2008-06-01

99

Configuration of water resources for a typical river basin in an arid region of China based on the ecological water requirements (EWRs) of desert riparian vegetation  

NASA Astrophysics Data System (ADS)

Desert riparian vegetation is a natural cover promoting the stability and development of inland river ecosystems in arid regions. Calculating the ecological water requirements (EWRs) of desert riparian vegetation is an important step in achieving reasonable water utilization. Therefore, this study examined the Tarim River, located in an extremely arid region of China, and collected relevant data on hydrology, weather and vegetation using remote sensing. Subsequently, we analyzed the spatial distribution of the desert riparian vegetation in four sections of the Tarim River and calculated the EWR of the desert riparian vegetation using the phreatic evaporation model; additionally, we determined the required runoffs at five hydrologic stations based on the water balance principle. Ultimately, the necessary protection ranges and goals for desert riparian vegetation were established according to the water resource variations in the Tarim River. Our research showed that the total area of desert riparian vegetation along the Tarim River is 16,285.3 km2; this distribution area gradually decreased as the distance from the river increased, and areas varied in the different river sections. The EWRs of desert riparian vegetation from Sections 1 to 5 are 5.698 × 108, 7.585 × 108, 4.900 × 108, 4.101 × 108 m3 and 1.078 × 108 m3, respectively. Therefore, the total EWR of the study region is 23.362 × 108 m3. In terms of the transpiration law of the "unimodal type", the peak value of EWR of natural vegetation occurs in July, and the decreasing trend appears in the other months. Based on the water balance principle, the required runoffs in Alar, Xinquman, Yingbaza, Wusiman and Qiala were determined to be 47.105 × 108, 35.174 × 108, 22.734 × 108, 15.775 × 108 and 7.707 × 108 m3, respectively. According to the water resource frequency and the EWR of the desert riparian vegetation along the Tarim River, we divided the region into three protection ranges: key protection (8.9-11.8 km from the river), basic protection (15.8-21.8 km from the river) and influence protection (43.0 km from the river). This research not only provides a reasonable calculation method for EWR on the scale of a river basin but also supports the healthy development of the desert riparian vegetation ecosystem and helps to achieve the optimal water allocation for this river.

Ling, Hongbo; Guo, Bin; Xu, Hailiang; Fu, Jinyi

2014-11-01

100

A debris flow deposit in alluvial, coal-bearing facies, Bighorn Basin, Wyoming, USA: Evidence for catastrophic termination of a mire  

USGS Publications Warehouse

Coal and clastic facies investigations of a Paleocene coal-bearing succession in the Grass Creek coal mine, southwestern Bighorn Basin, Wyoming, USA, suggest that disruption of peat accumulation in recurrent mires was caused by the repetitive progradation of crevasse splays and, ultimately, by a catastrophic mass movement. The mass movement, represented by deposits of debris flow, marked the termination of significant peat accumulation in the Grass Creek coal mine area. Megascopic and microscopic analyses of coal beds exposed along the mine highwalls suggest that these deposits developed in low-lying mires, as evidenced primarily by their ash yields and maceral composition. Disruption of peat accumulation in successive mires was caused by incursions of sediment into the mire environments. Termination by crevasse splay progradation is represented by coarsening-upward successions of mudrock and tabular, rooted sandstone, which overlie coal beds in the lower part of the coal-bearing interval. A more rapid process of mire termination by mass movement is exemplified by a debris flow deposit of diamictite, which overlies the uppermost coal bed at the top of the coal-bearing interval. The diamictite consists of a poorly sorted, unstratified mixture of quartzite cobbles and pebbles embedded in a claystone-rich or sandy mudstone matrix. Deposition of the diamictite may have taken place over a matter of weeks, days, or perhaps even hours, by catastrophic flood, thus reflecting an instantaneous process of mire termination. Coarse clastics and mud were transported from the southwest some 20-40 km as a viscous debris flow along stream courses from the ancestral Washakie Range to the Grass Creek area, where the flow overrode a low-lying mire and effectively terminated peat accumulation. ?? 1994.

Roberts, S.B.; Stanton, R.W.; Flores, R.M.

1994-01-01

101

Early Holocene fluvial activity from the sedimentology and palaeohydrology of gravel terrace in the semi arid Mahi River Basin, India  

NASA Astrophysics Data System (ADS)

Palaeocompetence analysis and palaeodischarge estimation techniques are applied to a late Pleistocene-early Holocene gravel terrace in the Mahi River Basin, western India. Terrace sedimentology, comprising gravels overlain by sand lithofacies suggests a gradual change in palaeohydrological conditions marking a switch from braided to meandering fluvial styles. The discharge values for the gravel bedforms based on the clast size and the cross bed set thickness are estimated between ˜150-180 m3 s-1 comparable with the present day observed values albeit with a much higher competence. Results indicate that fluvial aggradation occurred under low discharge conditions with intermittent high discharge events depositing longitudinal gravel bars. The incision of these gravel bars and the formation of terraces can be attributed to the higher discharge regime post 9.2 ka. The study further indicates that whereas the aggradation of the gravel terrace during the early Holocene was controlled by the large sediment influx, the incision that followed was in response to the increase in the discharge and competence of the river flow.

Sridhar, Alpa; Chamyal, L. S.; Bhattacharjee, Falguni; Singhvi, A. K.

2013-04-01

102

Impact of wind erosion on detecting active tectonics from geomorphic indexes in extremely arid areas: a case study from the Hero Range, Qaidam Basin, NW China  

NASA Astrophysics Data System (ADS)

Geomorphologic analysis has been used widely to detect active tectonics in regions where fluvial incision is the major erosional process. In this paper, however, we assess the feasibility of utilizing these frequently-used geomorphic indexes (e.g., hypsometric curves, longitudinal channel profiles, normalized stream length-gradient (SLK) index) to determine active tectonics in extremely arid areas where wind erosion also plays an important role. The case study is developed on the Hero Range in the western Qaidam Basin, one of the driest regions on Earth with severe wind erosion since late Pliocene. The result shows that in the west and south sectors, as well as the western part of the east sector, of the Hero Range where fluvial incision prevails, these geomorphic indexes are good indicators of active faulting and consistent with the geological result based on study of fault traces, scarps, faulted Holocene fans and historical seismicity within the past four decades. In contrast, along the northeastern margin (the NE and the SE parts of the east sector) of the range where wind erosion is also important, the results from the geomorphic indexes show quite active tectonics, contrary with the geological evidence favoring weakly active tectonics. Moreover, the positive SLK anomaly lies oblique to the fault trace and the anticline axis but parallel to the wind direction. To reconcile the contradiction, we propose that wind erosion caused by northwestern winds has a tendency to make geomorphic indexes exhibit anomalous values that indicate higher activities, by way of (1) lowering the base-level to generate knickpoints on the longitudinal channel profiles and therefore positive SLK anomalies, and (2) lateral erosion of the mountain front making the hypsometric curves and even the longitudinal channel profiles more convex, and producing obvious slope breaks.

Wu, Lei; Xiao, Ancheng; Yang, Shufeng

2014-11-01

103

Vegetation and geomorphic significance of the riparian greenline in the Sprague River basin, southern Oregon: implications for biogeomorphic monitoring of riparian corridors in semi-arid mountain valleys  

NASA Astrophysics Data System (ADS)

Like many regions in the western U.S., valley-floor environments of the semi-arid Sprague River basin of southern Oregon are heavily irrigated and widely grazed by cattle. To better understand the impacts of grazing and other land uses on river quality, the Klamath Tribes have begun a long-term, basin-wide program aimed at: (1) establishing baseline geomorphic and vegetative conditions along the Sprague River and its tributaries, and (2) monitoring changes in these conditions over time. Because of its widespread use and ease of application, determining the composition of the lowest line of perennial vegetation above baseflow, or the “greenline,” has been included. The goal of this paper is to summarize results of 38 greenline surveys conducted at 19 sites in 2008-9 and to explore geomorphic hypotheses that may explain vegetation patterns evident in the surveys. Spikerush (Eleocharis ssp.) and reed-canary grass (Phalaris arudinacea) were the most commonly occurring vegetation in the greenline across all sites. Because these species are aggressive colonizers, they indicate high availability of fresh alluvium, which may be associated with sustained channel-bank disturbance. Sedges dominated some portions of the greenline at most of the sites, but occurred in less abundance. The late successional or early-to-late transitional state of these sedges, combined with their relatively low frequency, further supports the hypothesis that channel-bank systems remain chronically disturbed and dynamic. Grazing is common, but variable in intensity, at nearly all of the study sites, likely contributing to the persistence of channel-bank disturbance. Among meandering channels, the richness of dominant species (i.e., “community diversity”) was higher on the outer bends than on the inner bends of meanders at 10 of 12 sites. The variability of geomorphic surfaces (old floodplain, new floodplain, failed bank, accreted toe, etc.) incorporated in the greenline by the spatially discontinuous processes of channel-bank erosion and failure on the outer meander bends appears to increase the types of habitats surveyed and their combined biodiversity. In contrast, the spatial continuity of bar accretion on the inner meander bends appears to result in a more uniform geomorphic setting with fewer dominant species in the greenline. Despite widespread recognition that geomorphic processes influence riparian vegetation, factors such as the type and severity of bank erosion, the location of the survey with respect to meander geometry, and the type of geomorphic surface underlying greenline observations are not explicitly included in published guidance for biogeomorphic monitoring of the riparian greenline. Inclusion of such factors would improve communication, study design, and application of research by fluvial geomorphologists, riparian ecologists, and resource managers utilizing the greenline methodology.

Hughes, M. L.; Leeseberg, C.

2009-12-01

104

Tectonically induced climate and its control on the distribution of depositional systems in a continental foreland basin, Cloverly and Lakota Formations (Lower Cretaceous) of Wyoming, U.S.A.  

NASA Astrophysics Data System (ADS)

Continental sediments of the Cloverly and Lakota Formations (Lower Cretaceous) in Wyoming are subdivided into three depositional systems: perennial to intermittent alluvial, intermittent to ephemeral alluvial, and playa. Chert-bearing sandstones, conglomerates, carbonaceous mudrocks, blocky mudrocks, and skeletal limestones were deposited by perennial to intermittent alluvial systems. Carbonaceous mudrocks contain abundant wood fragments, cuticle and cortical debris, and other vascular plant remains representing deposition in oxbow lakes, abandoned channels, and on floodplains under humid to seasonal conditions. Intraformational conglomerates, sandstones, bioturbated and blocky mudrocks with caliche nodules, and bioturbated limestones characterize deposition in intermittent to ephemeral alluvial systems. Bioturbated limestones are encased in bioturbated mudrocks with abundant pseudo-slickensides. The presence of caliche nodules in some of the blocky to bioturbated mudrocks is consistent with supersaturation and precipitation of calcium carbonate from groundwater under semi-arid conditions. Caliche nodules, pseudo-slickensides, and carbonate-rich floodplain sediments are interpreted to have been deposited by intermittent to ephemeral alluvial systems under seasonal to semi-arid climatic conditions. Laminated mudrocks, siltstones, vuggy carbonates, bedded to nodular evaporites, pebbly mudrocks, and diamictites were deposited in evaporative alkaline lakes or playas. Pebbly mudrocks and diamictites are interpreted to represent deposition from channelized and unchannelized hyperconcentrated flows on a playa, resulting from intense rain events within the basin. The areal abundance and distribution of these depositional systems change systematically across the overfilled portion of the Early Cretaceous Cordilleran foreland basin in Wyoming. The lower part (A-interval) of the Cloverly and Lakota Formations is characterized by deposits of perennial to intermittent rivers that existed 300 to 1000 km east of the Sevier fold-and-thrust belt. Proximal to the Sevier fold-and-thrust belt, the A-interval of the Cloverly Formation and upper Ephraim Formation of the Gannett Group are typified by deposits of intermittent to ephemeral rivers and their associated floodplains. In the middle part (B-interval) of the Cloverly Formation, intermittent to ephemeral alluvial systems expand to 600 km into the basin. The upper part (C-interval) of the Cloverly Formation is characterized by playa deposits in the Bighorn and Wind River Basins and intermittent to ephemeral alluvial deposits along the front of the ancestral Sevier Mountains. Deposits of perennial to intermittent alluvial systems in the C-interval of the Cloverly and Lakota Formations are restricted to the Black Hills region, almost 900 km to the east of the Sevier Mountains. The change in the areal distribution of depositional systems through time within this continental foreland basin may be attributed to the development of a rain shadow associated with the uplift of the Sevier Mountains in the Early Cretaceous.

Elliott, William S.; Suttner, Lee J.; Pratt, Lisa M.

2007-12-01

105

A comparison and integration of tree-ring and alluvial records of fire history at the Missionary Ridge Fire, Durango, Colorado, USA  

Microsoft Academic Search

We used tree-ring and alluvial sediment methods to reconstruct past fire regimes for a mixed conifer forest within a 1 km2 drainage basin which was severely burned by a wildfire near Durango, Colorado. Post-fire debris flow events incised the valley-filling alluvial sediments in the lower basin, and created exposures of fire-related of deposits of late-Holocene age. Tree-ring and alluvial sediment

Erica Bigio; Thomas W. Swetnam; Christopher H. Baisan

2010-01-01

106

The Tabernas alluvial fan and lake system, southeast Spain: applications of mineral magnetic and pedogenic iron oxide analyses towards clarifying the Quaternary sediment sequences  

Microsoft Academic Search

Mineral magnetic and soil iron oxide data are applied to questions of relative age correlation of alluvial fans and lake sediments in the Tabernas basin, southeast Spain, within a context of interaction between tectonics and climatic change. Within the Tabernas basin, the sediment sequences and morphological evolution of late Quaternary alluvial fans suggest climatic change as the primary control. The

Adrian M Harvey; Gez Foster; Jack Hannam; Anne E Mather

2003-01-01

107

The origin of groundwater in Zhangye Basin, northwestern China, using isotopic signature  

NASA Astrophysics Data System (ADS)

Zhangye Basin, in arid northwestern China, has recently been repeatedly flooded by rising groundwater. Isotope signatures of sampled waters gained insight into the recharge source of the groundwater. The summer Heihe River water and most of the spring water in Zhangye and Yongchang basins plotted above the global meteoric water line (GMWL) on the ?18O-?D plot. The spring water had R/Ra ratio >1, low TDS and high tritium, which indicates origin from Qilian Mountain glacier meltwater. The groundwater of Qilian Mountains was transported to the Hexi Corridor (in which Zhangye Basin is located) through underground fault zones. Additionally, some of the groundwater in the alluvial plain, and all spring water surrounding Zhangye Basin, plotted below the GMWL on the ?18O-?D plot along an evaporation line, and had R/Ra ratio < 1 and high TDS. It is proposed that the Tibetan rivers or lakes source the Hexi Corridor groundwater through either the NE-trending or NW-trending buried fault zones. The isotopic signatures presented as part of this study rule out the conventional viewpoint that groundwater of the Zhangye Basin was recharged by local precipitation and infiltration of Heihe River water on the alluvial plain.

Chen, Jiansheng; Liu, Xiaoyan; Sun, Xiaoxu; Su, Zhiguo; Yong, Bin

2014-03-01

108

Deep arid system hydrodynamics 2. Application to paleohydrologic reconstruction using vadose zone profiles from the northern Mojave Desert  

USGS Publications Warehouse

Site-specific numerical modeling of four sites in two arid alluvial basins within the Nevada Test Site employs a conceptual model of deep arid system hydrodynamics that includes vapor transport, the role of xeric vegetation, and long-term surface boundary transients. Surface boundary sequences, spanning 110 kyr, that best reproduce measured chloride concentration and matric potential profiles from four deep (230-460 m) boreholes concur with independent paleohydrologic and paleoecological records from the region. Simulations constrain a pluvial period associated with infiltration of 2-5 mm yr-1 at 14-13 ka and denote a shift linked to the establishment of desert vegetation at 13-9.5 ka. Retrodicted moisture flux histories inferred from modeling results differ significantly from those determined using the conventional chloride mass balance approach that assumes only downward advection. The modeling approach developed here represents a significant advance in the use of deep vadose zone profile data from arid regions to recover detailed paleohydrologic and current hydrologic information.

Walvoord, M.A.; Phillips, F.M.; Tyler, S.W.; Hartsough, P.C.

2002-01-01

109

Spatio-temporal variations of precipitation in arid and semiarid regions of China: The Yellow River basin as a case study  

NASA Astrophysics Data System (ADS)

Daily precipitation data from 64 precipitation gauging stations within the Yellow River basin were analyzed by defining 17 precipitation indices with the aim to investigate space and time changes in precipitation characteristics. The modified Mann-Kendall trend test method was used to detect trends in the precipitation series. The influence of Interdecadal Pacific Oscillation (IPO) on the basin precipitation was also investigated. Results indicate that: (1) the Yellow River basin is dominated by decreasing precipitation and precipitation deficit may further deteriorate the shortage of water resources. The middle Yellow River basin may encounter increasingly serious shortage of water resources and higher risk of floods would be expected in the lower Yellow River basin; (2) a higher risk of droughts can be expected in spring and autumn and precipitation in winter is increasing, which imply evident seasonality and seasonal shifts of precipitation changes within the basin; (3) short-duration consecutive precipitation events are prevalent in the basin and frequency and amount of short-duration consecutive precipitation events are increasing; (4) precipitation extremes are not dominant in the Yellow River basin, except for some regions in the North China Plain and rainstorm events are generally decreasing; and (5) no evident impact of IPO on the precipitation in the Yellow River basin is found. In this case, precipitation deficit would be a major problem the basin-scale water resources management may face in the future.

Zhang, Qiang; Peng, Juntai; Singh, Vijay P.; Li, Jianfeng; Chen, Yongqin David

2014-03-01

110

Late Miocene to Plio-Pleistocene fluvio-lacustrine system in the Karacasu Basin (SW Anatolia, Turkey): Depositional, paleogeographic and paleoclimatic implications  

NASA Astrophysics Data System (ADS)

The sedimentary record of the late Cenozoic Karacasu Basin, a long-lived continental half-graben from southwestern Turkey, is characterized by siliciclastic and carbonate deposits. Sedimentation was controlled by an active NW-SE trending major normal fault along the basin's southern margin and by climatically-induced lake-level changes. Detailed facies analysis subdivides the entire Neogene-Quaternary basin-fill into three distinct litostratigraphic units representing paleogeographic changes and sedimentation patterns throughout the basin evolution. Sedimentation commenced in the late Miocene with the deposition of proximal-medial alluvial fan and fluvial facies (Damdere Formation; FA1). At this stage, alluvial fans developed in elevated areas to the south, prograding towards the basin center. At the beginning of the Pliocene, fresh to slightly alkaline, shallow lake deposits (FA2a) of the Karacaören Formation formed. The lake became open and meromictic conditions developed (FA2b). Pollen data from the FA2b facies show that climate was arid to humid. Climate probably changed cyclically through time producing alternation of Artemisia steppe (cold and dry periods) and more forested vegetation (warm and wet). The open lake facies passes upwards into lake margin facies (FA2c), but it was still dominated by alkaline to slightly saline lake conditions. Sedimentation was almost continuous from the late Miocene to Pleistocene. In the early Quaternary, the basin was dissected by the re-activation of basin bounding faults. The unconformable base of the overlying Quaternary deposits (Karacasu Formation; FA3) reflected the basin's transformation from a half-graben into a full-graben system. Oxygen isotope data from carbonates show an alternation of humid climatic periods, when freshwater settings predominated, and semiarid/arid periods in which the basin hosted alkaline and saline water lakes. Neotectonic activity has rejuvenated many of the basin-bounding faults, causing development of talus aprons and local alluvial fans. The basin was progressively incised by modern rivers that have largely smoothed out the topographic relief of the graben margins. id="ab0010" The study highlights to the paleo-geography/-climatology in the east Mediterranean.

Alçiçek, Hülya; Jiménez-Moreno, Gonzalo

2013-06-01

111

Water sources accessed by arid zone riparian trees in highly saline environments, Australia  

Microsoft Academic Search

The flow regimes of arid zone rivers are often highly variable, and shallow groundwater in the alluvial aquifers can be very\\u000a saline, thus constraining the availability and quality of the major water sources available to riparian trees—soil water,\\u000a shallow groundwater and stream water. We have identified water sources and strategies used by riparian trees in more highly\\u000a saline and arid

Justin F. Costelloe; Emily Payne; Ian E. Woodrow; Elizabeth C. Irvine; Fred W. Leaney

2008-01-01

112

Co-contamination of As and F in alluvial aquifer  

NASA Astrophysics Data System (ADS)

Co-contamination of As and F is frequently observed in alluvial aquifers of many countries including Argentina, Mexico, China, and Pakistan. However, processes causing this phenomenon are still poorly understood. In arid or semi-arid areas, the aquifers are generally under oxidizing condition and As and F show a good correlation. In contrast, groundwaters under reducing condition generally show a poorer correlation. In this study, we explored the geochemical mechanisms causing the co-contamination of As and F and their poorer correlation in the reducing environment by investigating alluvial groundwaters of the Mankyeong River floodplain, Korea. For this study, we collected 72 groundwater samples from 42 shallow wells placed into the alluvial aquifer. Desorption experiments using soils collected from the study area were also performed. Groundwater chemistry data showed that waters are under strong reducing condition and the reductive dissolution of Fe oxides was the main process increasing As concentration in groundwaters. The co-contamination was also observed in the study area and F did not show a good correlation with As. F showed concentrations increasing with pH. Desorption experiments also showed the dependences of As and F on pH. The experiments using soils treated with Na citrate-NaHCO3-dithonite solution indicated that iron oxides were the main phases hosting both As and F in soils. In our study area, pH of groundwaters increases due to a series of reduction reactions, and which increased F concentration by desorption from iron oxides. This result suggests that sharing the same adsorption hosts and the pH increased by reduction reactions are the main reason for the co-occurrence of As and F in alluvial groundwater under reducing environments. The lack of correlation between As and F was derived by the precipitation of As as sulfides in sulfate reducing condition. However, the correlation could be much better in the oxidizing condition because As released from iron oxides by pH increase cannot be removed as sulfides.

Kim, S.; Kim, K.; Kim, B.; Zhu, W.; Lee, E.; Ko, K.

2010-12-01

113

Holocene dust deposition rates in Australia’s Murray-Darling Basin record the interplay between aridity and the position of the mid-latitude westerlies  

NASA Astrophysics Data System (ADS)

Millennial scale variability in the strength/position of the mid-latitude westerlies, as interpreted from rates of dust deposition in an alpine mire south-eastern Australia, is demonstrated to be a major driver of climate variability during the mid to late Holocene. Dust deposition rates were calculated with a trace element provenance model. This approach is capable of distinguishing between sedimentation of local alluvium and genuine deposition of aeolian dust into the studied mire. Low dust deposition from 6500 to 5500 cal. BP occurred during a period of enhanced south-westerly winds which advected moisture into south-eastern Australia resulting in wet conditions. A subsequent dust pulse at 5500-4000 cal. BP is interpreted as a relaxation in south-westerlies resulting in a more arid phase and possibly enhanced climate variability. Reduced dust deposition between 4000 and 2000 cal. BP indicates a return to increased precipitation/moisture in the lower MDB associated with increased south-westerly geostrophic flow. The onset of more arid conditions after 2000 cal. BP implies a reduction in the frequency of precipitation bearing south-westerly winds. A final further significant finding from this study is the identification of a major dust deposition/wind erosion episode coinciding with the onset of European land clearing and agriculture in Australia.

Marx, Samuel K.; Kamber, Balz S.; McGowan, Hamish A.; Denholm, John

2011-11-01

114

Ground-Water Recharge in the Arid and Semiarid Southwestern United States --  

E-print Network

and interglacial periods. Precipitation patterns reflect global-scale interactions among the oceans, atmo- sphere processes that led to numerous, variably connected alluvial-filled basins, exposure of extensive Paleozoic

115

Sedimentation of the Triassic Jurassic Adigrat Sandstone Formation, Blue Nile (Abay) Basin, Ethiopia  

NASA Astrophysics Data System (ADS)

Exploration of oil and gas deposits in the Blue Nile Basin targeted the Adigrat Sandstone Formation as a reservoir objective. Conglomerates, gravely sandstones, coarse to medium-grained sandstones, very fine-grained cross-bedded sandstones, siltstones and mudstones of the Adigrat Sandstone Formation were deposited in semi-arid to arid climates. The North-western highlands are the main source for the sedimentation. The poorly-sorted, crudely-bedded conglomerates and gravely sandstones are interpreted as alluvial fan deposits. The basal polymictic orthoconglomerate passes up vertically into gravely sandstone, possibly indicating proximal to mid-fan sedimentation. The alluvial fan sedimentation passes up vertically into channel, point bars and flood-plain fines. The meandering river sedimentation is characterized by single and amalgamated multi-storey sandstone bodies. In places, the uppermost part of the Adigrat Sandstone Formation is represented by coal-bearing sediments possibly reflect lacustrine depositional environment. The medium-coarse-grained sandstone is a possible oil and gas reservoir, whilst the fine-grained sediments are a possible gas reservoir.

Wolela, A.

2008-09-01

116

Flux and composition of wind-eroded dust from different landscapes of an arid inland river basin in north-western China  

Microsoft Academic Search

Using a simple æolian dust sampler, dust plumes generated from five landscape types (dry lakebed, gobi, farmland, seriously degraded grassland and sandy desert lands) in the inland basin of the Heihe River of north-western China, were monitored, along with wind velocity and temperature, from 2 April to 30 May 2001. Dust fluxes, conditions under which they occurred and an elemental

Genxu Wang; Tuo Wanquan; Du Mingyuan

2004-01-01

117

Using cosmogenic nuclides to contrast rates of erosion and sediment yield in a semi-arid, arroyo-dominated landscape, Rio Puerco Basin, New Mexico  

Microsoft Academic Search

Analysis of in-situ-produced 10 Be and 26 Al in 52 fluvial sediment samples shows that millennial- scale rates of erosion vary widely (7 to 366 m Ma ? ? ? ? ?1 ) through the lithologically and topo- graphically complex Rio Puerco Basin of northern New Mexico. Using isotopic analysis of both headwater and downstream samples, we determined that the

Paul R. Bierman; Joanna M. Reuter; Milan Pavich; Allen C. Gellis; Marc W. Caffee; Jennifer Larsen

2005-01-01

118

Using the Bidirectional Reflectance Distribution Function (BRDF) for remotely mapping surface roughness on alluvial fans: A comparison of Death Valley, CA to Mojave Crater on Mars  

NASA Astrophysics Data System (ADS)

The Bidirectional Reflectance Distribution Function (BRDF) describes how incoming light from a given direction is reflected from specific surfaces in response to different incoming solar radiation angles. The amount and directionality of reflected light is a function of surface roughness and orientation. The goal of this study is to assess whether a BRDF based approach may be applicable for creating surface roughness maps for Martian alluvial fans. Landsat 7 satellite imagery is used to make classifications of surfaces with different roughness and spectral properties for alluvial fan surfaces in Death Valley, California. The resulting classes have been interpreted to represent surfaces of different ages and also different deposit types. In Death Valley, older surfaces are classified based on the amount of shadowing due to gully formation, differences in the amount of surface smoothness from desert pavement formation, and desert varnish color variations. In contrast, the most recently formed surfaces have an assemblage of classes that represent surface deposits of different grain size and sorting, as well as different landform types - incised channels and elevated bars. Many Death Valley fans have a telescoping morphology where progressively younger surfaces reach basin-ward. This is more evident on some fans using a BRDF classification. A similar map was made for depositional landforms within Mojave Crater on Mars, identified as sub-kilometer alluvial fans by Williams and Malin (2008). These alluvial fans are the youngest found on Mars (Amazonian age) and have topographic similarities to fans in the southwestern US. Any geomorphic similarities between Death Valley fans and those within Mojave Crater can be assessed using surface roughness. Imagery from both the High Resolution Imaging Experiment (HiRISE) and Context Camera (CTX) onboard the Mars Reconnaissance Orbiter (MRO) were used to compare differences in spatial resolution on BRDF classifications. The resulting surface roughness maps are strikingly similar in classes and patterns to many fans within Death Valley. The surfaces interpreted by Williams and Malin (2008) to be evidence of multiple flow events are clearly classified using BRDF. In addition to age differences, possible locations of materials with different grain size and sorting are also identified. Since the BRDF classes of certain surface features on Earth and Mars fans largely overlap, field observations for each class type made for Death Valley fan surfaces may be useful for understanding the past fluvial processes on Mars and their similarities with fan forming processes in arid regions on Earth. This remote sensing approach has the potential to provide a tool for studying fans that may be inaccessible or too large for extensive fieldwork.

Doyle, S. L.; Wilkinson, M. J.; Scuderi, L. A.; Weissmann, G. S.; Scuderi, L. J.

2011-12-01

119

INFLUENCE OF SEDIMENT SUPPLY, LITHOLOGY, AND WOOD DEBRIS ON THE DISTRIBUTION OF BEDROCK AND ALLUVIAL CHANNELS  

EPA Science Inventory

Field surveys in the Willapa River basin, Washington State, indicate that the drainage area?channel slope threshold describing the distribution of bedrock and alluvial channels is influenced by the underlying lithology and that local variations in sediment supply can overwhelm ba...

120

Late Quaternary Upper Mississippi River alluvial episodes and their significance to the Lower Mississippi River system  

Microsoft Academic Search

The period in the Upper Mississippi Valley (UMV) from about 25 000 years B.P. until the time of strong human influence on the landscape beginning about 150–200 years ago can be characterized by three distinctly different alluvial episodes. The first episode is dominated by the direct and indirect effects of Late Wisconsin glacial ice in the basin headwaters. This period,

James C. Knox

1996-01-01

121

Aerial Transient Electromagnetic Surveys of Alluvial Aquifers in Rural Watersheds of Arizona  

Microsoft Academic Search

Development in rural areas of Arizona has led the State of Arizona (Arizona Department of Water Resources), in cooperation with the Arizona Water Science Center of the U.S. Geological Survey, to sponsor investigations of the hydrogeologic framework of several alluvial-basin aquifers. An efficient method for mapping the aquifer extent and lithology was needed due to sparse subsurface information. Aerial Transient

D. R. Pool; J. B. Callegary; R. W. Groom

2006-01-01

122

Climate changes and their impacts on water resources in the arid regions: a case study of the Tarim River basin, China  

Microsoft Academic Search

Streamflow series of five hydrological stations were analyzed with aim to indicate variability of water resources in the Tarim\\u000a River basin. Besides, impacts of climate changes on water resources were investigated by analyzing daily precipitation and\\u000a temperature data of 23 meteorological stations covering 1960–2005. Some interesting and important results were obtained: (1)\\u000a the study region is characterized by increasing temperature,

Qiang Zhang; Chong-Yu Xu; Hui Tao; Tao Jiang; Yongqin David Chen

2010-01-01

123

The morphology of alluvial rivers  

NASA Astrophysics Data System (ADS)

Alluvial rivers form their channel in the material they transport, producing a varied collection of bed shapes, from deep single-thread channels to wide and shallow braids. Laboratory flumes produce similar morphologies at the centimeter scale, while braided rivers can spread over a few kilometers, suggesting that the same basic phenomena express themselves across scales. We conjecture that the competition between gravity and diffusion, at the scale of a sediment grain, controls the morphology of alluvial rivers. The classical threshold theory, which neglects diffusion, explains the relationship between river width and discharge [1]. However, it is valid only when bedload transport vanishes. When the river transports sediments, gravity pulls the grains towards the center of the channel, precluding equilibrium within this theoretical framework [2]. Based on laboratory experiments, we suggest that each bedload grain follows a random walk in the transverse direction. Consequently, sediments diffuse towards the less active areas of the bed, thus counteracting gravity by continuously rebuilding the river's bank. As the sediment discharge increases, this balance requires a wider and narrower channel, until the river becomes unstable. [1] R.E. Glover and Q.L. Florey, Stable channel profiles, US Bur. Reclamation, Hydr., 325, 1951. [2] G. Parker, Self-formed straight rivers with equilibrium banks and mobile bed. Part 2. The gravel river, J. Fluid Mech., 89, 1, 1978.

Devauchelle, O.; Seizilles, G.; Lajeunesse, E.; Bak, M. T.; Marc, O.; Metivier, F.

2012-12-01

124

Geomorphological evolution of the Tilcara alluvial fan (Jujuy Province, NW Argentina): Tectonic implications and palaeoenvironmental considerations  

NASA Astrophysics Data System (ADS)

The development and evolution of the Tilcara alluvial fan, in the Quebrada de Humahuaca (Andean Eastern Cordillera, NW Argentina), has been analysed by using geomorphological mapping techniques, sedimentological characterisation of the deposits and OSL chronological methods. It is a complex segmented alluvial fan made up of five evolutionary stages (units Qf1, Qf2, Qf3, Qf4 and Qf5) developed under arid climatic environments as well as compressive tectonic conditions. Segmentation processes, including aggradation/entrenchment cycles and changes in the location of the depositional lobe, are mainly controlled by climatic and/or tectonic changes as well as channel piracy processes in the drainage system. Alluvial fan deposits include debris flows, sheet flows and braided channel facies associated with high water discharge events in an arid environment. The best mean OSL age estimated for stage Qf2 is 84.5 ± 7 ka BP. In addition, a thrust fault affecting these deposits has been recognized and, as a consequence, the compressive tectonics must date from the Upper Pleistocene in this area of the Andean Eastern Cordillera.

Sancho, Carlos; Peña, José Luis; Rivelli, Felipe; Rhodes, Ed; Muñoz, Arsenio

2008-07-01

125

Groundwater research in the alluvial of river Sitnica, Kosova  

NASA Astrophysics Data System (ADS)

In the today's world, the problems of too much, too little or too polluted water are increasing at a rapid rate. Water resources in Kosova are relatively small, the average of annual runoff is 3.61miliard m3, relatively 113m3/s. Territory of Kosova is divided in four river basins: Drini i Bardhë, Ibri, Morava e Binqës and Lepenci. Sitnica River belongs to the river basin Ibri. The total surface of in this river is 2.861km2, the average of the annual rainfalls is 686mm, from which around 93mm (13.6%) flows on the surface and around 593mm (84.6%) infiltrates. In this case study are applied different methods for groundwater research and calculations of hydro-geological parameters in the alluvial of river Sitnica. Geophysics researches carried out with geo-electrical sounding and geo-electrical profile line. The goal of the geophysics researches is to identify hydrogeological collector and to determine the best position for placement of the piezometers. The geophysics research are done in aquifer area, in which 10 profiles line with different lengths and placed in distance from 30 m between each other are done. After finishing of the geophysics works, seven drilling wells with general length from 95.5 m are completed. Based to the testing results of two drilling wells we have concluded that the quantity of 27.4(l/sec) water can be exploited. The achieved results from application of those methods in this case study show that alluvial of river Sitnica are rich with groundwater. Based to the statistics the population is increasing in Kosova also water needs will be increasing too, so it is necessary to explore the existing groundwater for improving drinking water supply, industrial waters, agriculture etc. Key works: river, alluvial, geophysics researches, drilling wells, hydrogeological collector, water

Avdullahi, S.; Fejza, I.; Osmani, L.

2009-04-01

126

Geomorphic Processes and Remote Sensing Signatures of Alluvial Fans in the Kun Lun Mountains, China  

NASA Technical Reports Server (NTRS)

The timing of alluvial deposition in arid and semiarid areas is tied to land-surface instability caused by regional climate changes. The distribution pattern of dated deposits provides maps of regional land-surface response to past climate change. Sensitivity to differences in surface roughness and composition makes remote sensing techniques useful for regional mapping of alluvial deposits. Radar images from the Spaceborne Radar Laboratory and visible wavelength images from the French SPOT satellite were used to determine remote sensing signatures of alluvial fan units for an area in the Kun Lun Mountains of northwestern China. These data were combined with field observations to compare surface processes and their effects on remote sensing signatures in northwestern China and the southwestern United States. Geomorphic processes affecting alluvial fans in the two areas include aeolian deposition, desert varnish, and fluvial dissection. However, salt weathering is a much more important process in the Kun Lun than in the southwestern United States. This slows the formation of desert varnish and prevents desert pavement from forming. Thus the Kun Lun signatures are characteristic of the dominance of salt weathering, while signatures from the southwestern United States are characteristic of the dominance of desert varnish and pavement processes. Remote sensing signatures are consistent enough in these two regions to be used for mapping fan units over large areas.

Farr, Tom G.; Chadwick, Oliver A.

1996-01-01

127

Use of TOPSAR digital elevation data to determine the 3-dimensional shape of an alluvial fan  

NASA Technical Reports Server (NTRS)

Landforms in arid regions record the interplay between tectonic forces and climate. Alluvial fans are a common landform in desert regions where the rate of uplift is greater than weathering or sedimentation. Changes in uplift rate or climatic conditions can lead to isolation of the currently forming fan surface through entrenchment and construction of another fan either further from the mountain front (decreased uplift or increased runoff) or closer to the mountain front (increased uplift or decreased runoff). Thus, many alluvial fans are made up of a mosaic of fan units of different age, some older than 1 million years. For this reason, determination of the stages of fan evolution can lead to a history of uplift and runoff. In an attempt to separate the effects of tectonic (uplift) and climatic (weathering, runoff, sedimentation) processes on the shapes of alluvial fan units, a modified conic equation developed by Troeh (1965) was fitted to TOPSAR digital topographic data for the Trail Canyon alluvial fan in Death Valley, California. This allows parameters for the apex position, slope, and radial curvature to be compared with unit age.

Farr, Tom G.

1995-01-01

128

Geophysical and Hydrological Characterization of Alluvial Fans in the Valle El Sauz Encinillas, Chihuahua, México.  

NASA Astrophysics Data System (ADS)

The Valle El Sauz Encinillas (VESE) is located 92 km north of Chihuahua City, México. Despite being the principal aquifer feeding Chihuahua City, and being flanked by two well studied geological features (Bloque Calera-Del Nido to the West, and the Sierra Peña Blanca to the East), a lack of available hydrogeological data prevails in the valley. The goals of this study are two: 1) geomorphometrical analysis of the sub-basins and alluvial fans, and 2) determination of the alluvial fan geoelectrical units via electrical-resistivity soundings. The Basin and Range system forms a closed sub-basin with a lacustrine basin system in extinction process. The aquifer is located in alluvial Quaternary sediments, with varying granulometry, reaching a thickness of 600 meters at the center of the valley. The biggest alluvial fan in the VESE is located at the Cañón de Santa Clara, and intersects the playa-lake deposits of the Laguna de Encinillas. This fan has a surface of 73.2 km2 and an average slope of 0.437°. The geomorphometrical analysis included the sub-basins, currents, and the fans in the area. These analyses allow a comparison between alluvial fans in the VESE and those in Death Valley, California, USA. The alluvial fans in both areas show a similar behavior in all plots. Twenty electrical resistivity soundings (Schlumberger array, AB/2 distance of 400 m) were performed in the alluvial fan. The basement and four other geoelectrical units were identified in the fan. The geophysical data, granulometric determinations, plus geochemical information of twelve wells in the area were analyzed. These data show how the decrease in granulometry, both frontally and laterally in the fan, results in a rise of the hydraulic conductivity and transmisivity values (water wells in Los Sauces and El Faro). However, both the permeability and the water quality in its distal portion, are affected by the playa lake deposits, the raising ratio of clay-size sediments (and evaporites) in the center of the valley, near to Laguna de Encinillas.

Villalobos-Aragón, A.; Chávez-Aguirre, R.; Osuna-Vizcarra, A.; Espejel-García, V. V.

2007-05-01

129

Geochemical evolution of groundwater salinity at basin scale: a case study from Datong basin, Northern China.  

PubMed

A hydrogeochemical investigation using integrated methods of stable isotopes ((18)O, (2)H), (87)Sr/(86)Sr ratios, Cl/Br ratios, chloride-mass balance, mass balance and hydrogeochemical modeling was conducted to interpret the geochemical evolution of groundwater salinity in Datong basin, northern China. The ?(2)H, ?(18)O ratios in precipitation exhibited a local meteoric water line of ?(2)H = 6.4 ?(18)O -5 (R(2) = 0.94), while those in groundwater suggested their meteoric origin in a historically colder climatic regime with a speculated recharge rate of less than 20.5 mm overall per year, in addition to recharge from a component of deep residual ancient lake water enriched with Br. According to the Sr isotope binary mixing model, the mixing of recharges from the Shentou karst springs (24%), the western margins (11%) and the eastern margins (65%) accounts for the groundwater from the deep aquifers of the down-gradient parts in the central basin is a possible mixing mechanism. In Datong, hydrolysis of silicate minerals is the most important hydrogeochemical process responsible for groundwater chemistry, in addition to dissolution of carbonate and evaporites. In the recharge areas, silicate chemical weathering is typically at the bisiallitization stage, while that in the central basin is mostly at the monosiallitization stage with limited evidence of being in equilibrium with gibbsite. Na exchange with bound Ca, Mg prevails at basin scale, and intensifies with groundwater salinity, while Ca, Mg exchange with bound Na locally occurs in the east pluvial and alluvial plains. Although groundwater salinity increases with the progress of water-rock/sediment interactions along the flow path, as a result of carbonate solubility control and continuous evapotranspiration, Na-HCO3 and Na-Cl-SO4 types of water are usually characterized respectively in the deep and the shallow aquifers of an inland basin with a silicate terrain in an arid climatic regime. PMID:24737419

Wu, Ya; Wang, Yanxin

2014-05-01

130

Flow resistance in alluvial and mountain rivers  

NASA Astrophysics Data System (ADS)

Open channel flow resistance has been fruitfully studied in alluvial rivers. However, due to the complex dynamics of shallow water flow, there remains difficulties in the flow resistance study of mountain rivers. Most of studies about resistance in mountain rivers inherit the modifications of resistance relations in alluvial rivers despite significant differences existing in the mechanisms of flow resistance. Resistance relationships of mountain rivers are almost semi-experienced relying on field data. To the author's best knowledge, there is no unified description of the resistance relation covering both mountain and alluvial rivers. In this study, we aim to propose the first attempt on the uniform of the resistance relation. Fluid resistance is partitioned into skin friction and bed form drag through the partitioning of hydraulic radius. Corresponding to the skin friction and the bed form drag, the grain roughness and the bed form roughness are considered separately. We formulate the equations of the energy losses due to bed form drag in mountain rivers e.g. step-pool structures, considering its consistency with bed form drag of alluvial rivers. Thus bed form roughness of mountain rivers could be estimated referring to those of alluvial rivers. The consistent expression of bed form roughness allows a unified form drag formula suitable to both alluvial and mountain rivers by a modified Einstein flow intensity parameter. The formula agrees with the field survey data very well, demonstrating the inherent uniformity in the resistance relations of mountain and alluvial rivers to some extent.

Fu, X.; Zhang, L.; Ma, H.; Li, T.; Guo, D.

2013-12-01

131

Mid late Holocene hydrological changes in the Mahi River, arid western India  

NASA Astrophysics Data System (ADS)

This paper attempts to quantify contemporary and palaeo-discharges and changes in the hydrologic regime through the mid-late Holocene in the alluvial reach of the arid Mahi River basin in western India. The occurrence of terraces and pointbars high above active river levels and change in the width/depth ratio can be regarded as geomorphic responses to changes in discharge. Discharge estimates are made based on the channel dimensions and established empirical relations for the three types of channels: mid-late Holocene, historic (the channel that deposited extensive pointbars above the present-day average flow level) and the present ones. The bankfull discharge of the mid-late Holocene channel was ˜ 55 000 m 3 s - 1 and that of the historic channel was ˜ 9500 m 3 s - 1 , some ˜ 25 times and ˜ 5 times greater than that of the present river (2000 m 3 s - 1 ), respectively. Since the mid-late Holocene, the channel form has changed from wide, large-amplitude meanders to smaller meanders, and decreases in the width/depth ratio, unit stream power and the bed shear stresses have occurred. It can be inferred that there has been a trend of decreasing precipitation since the mid-late Holocene.

Sridhar, Alpa

2007-08-01

132

Modern and ancient alluvial fan deposits  

SciTech Connect

Understanding the structure and depositional processes of alluvial fans (river outwash deposits) has a special interest for those involved with the exploration of petroleum and many minerals. This collection of facsimile reprints of significant and classical research papers sheds new light on the subject. This reference covers the stratigraphy, sedimentology, and depositional processes of modern and ancient alluvial fans. Geographical areas considered include Arctic Canada, the American Southwest, Australia, Wyoming, Norway, and Spain. It includes a state-of-the-art introduction by the editor along with commentaries on all the papers included, a master author citation index and a subject index, and a chronological listing of early studies of alluvial fans.

Nilsen, T.H.

1985-01-01

133

Cenozoic North American Drainage Basin Evolution, Sediment Yield, and Accumulation in the Gulf of Mexico Basin  

NASA Astrophysics Data System (ADS)

The Cenozoic fill of the Gulf of Mexico basin contains a continuous record of sediment supply from the North American continental interior for the past 65 million years. Regional mapping of unit thickness and paleogeography for 18 depositional episodes defines patterns of shifting entry points of continental fluvial systems and quantifies the total volume of sediment supplied during each episode. Eight fluvio-deltaic depocenters, named for geographic similarities to entry points and drainage basins of modern rivers, are present. From southwest to northeast, they are the Rio Bravo, Rio Grande, Guadalupe, Colorado, Houston-Brazos, Red, Mississippi, and Tennessee axes. Sediment volume was calculated from hand-contoured unit thickness maps compiled from basin-wide well and seismic control. Using a GIS algorithm to sum volumes within polygons bounding interpreted North American river contribution, the total extant volume was then calculated. General compaction factors were used to convert modern volume to quantitative approximations of total grain volume. Grain volume rate of supply for each depositional episode was then calculated. Values vary by more than an order of magnitude. Supply rate has commonly varied by two-fold or more between successive depositional episodes. Sediment supply is a significant, independent variable in development of stratigraphic sequences within the Gulf basin. Paleogeographic maps of the continental interior for eleven Cenozoic time intervals display the evolving and complex interplay of intracontinental tectonism, climate change, and drainage basin evolution. Five tectono-climatic eras are differentiated: Paleocene late Laramide era; early to middle Eocene terminal Laramide era; middle Cenozoic (Late Eocene—Early Miocene) dry, volcanogenic era; middle Neogene (Middle—Late Miocene) arid, extensional era; and late Neogene (Plio—Pleistocene) monsoonal, epeirogenic uplift era. Sediment supply to the GOM reflects the interplay of (1) areal extent of river drainage basins, (2) source area relief, (3) climate of the source areas and tributary systems, (4) source lithology, and (5) sediment storage within the upper drainage basin. Climate has played an important and complex role in modulating supply. In wet tropical to temperate climate regimes, abundant runoff efficiently removed entrained sediment. Arid climate limited runoff; resultant transport-limited tributaries and trunk streams deposited aggradational alluvial aprons, storing sediment in the drainage basin even in the absence of a structural depression. Eolian deposition commonly accompanied such alluvial aggradation. In contrast, seasonality and consequent runoff variability favored erosion and efficient sediment evacuation from the upper parts of drainage basins. Tectonism has played a prominent but equally complex role. Elevation of uplands by compression, crustal heating, or extrusive volcanism created primary loci of erosion and high sediment yield. At the same time, accompanying subsidence sometimes created long-lived sediment repositories that intercepted and sequestered sediment adjacent to sources. Regional patterns of uplift and subsidence relocated drainage divides and redirected trunk stream paths to the Gulf margin.

Galloway, W.; Ganey-Curry, P. E.

2010-12-01

134

Improving assessment of groundwater-resource sustainability with deterministic modelling: a case study of the semi-arid Musi sub-basin, South India  

NASA Astrophysics Data System (ADS)

Since the 1990s, Indian farmers, supported by the government, have partially shifted from surface-water to groundwater irrigation in response to the uncertainty in surface-water availability. Water-management authorities only slowly began to consider sustainable use of groundwater resources as a prime concern. Now, a reliable integration of groundwater resources for water-allocation planning is needed to prevent aquifer overexploitation. Within the 11,000-km2 Musi River sub-basin (South India), human interventions have dramatically impacted the hard-rock aquifers, with a water-table drop of 0.18 m/a over the period 1989-2004. A fully distributed numerical groundwater model was successfully implemented at catchment scale. The model allowed two distinct conceptualizations of groundwater availability to be quantified: one that was linked to easily quantified fluxes, and one that was more expressive of long-term sustainability by taking account of all sources and sinks. Simulations showed that the latter implied 13 % less available groundwater for exploitation than did the former. In turn, this has major implications for the existing water-allocation modelling framework used to guide decision makers and water-resources managers worldwide.

Massuel, S.; George, B. A.; Venot, J.-P.; Bharati, L.; Acharya, S.

2013-11-01

135

Occurrence of arsenic species in algae and freshwater plants of an extreme arid region in northern Chile, the Loa River Basin.  

PubMed

This study reports data on arsenic speciation in two green algae species (Cladophora sp. and Chara sp.) and in five aquatic plants (Azolla sp., Myriophyllum aquaticum, Phylloscirpus cf. desserticola, Potamogeton pectinatus, Ruppia filifolia and Zannichellia palustris) from the Loa River Basin in the Atacama Desert (northern Chile). Arsenic content was measured by Mass spectrometry coupled with Inductively Coupled Plasma (ICP-MS), after acidic digestion. Liquid chromatography coupled to ICP-MS was used for arsenic speciation, using both anionic and cationic chromatographic exchange systems. Inorganic arsenic compounds were the main arsenic species measured in all samples. The main arsenic species in the extracts of freshwater algae and plants were arsenite and arsenate, whereas glycerol-arsenosugar (gly-sug), dimethylarsinic acid (DMA) and methylarsonic acid (MA) were present only as minor constituents. Of the samples studied, algae species accumulated more arsenic than aquatic plants. Total arsenic content ranged from 182 to 11100 and from 20 to 248 mg As kg(-1) (d.w.) in algae and freshwater plants, respectively. In comparison with As concentration in water samples, there was hyper-accumulation (>0.1% d.w.) in Cladophora sp. PMID:22981629

Pell, Albert; Márquez, Anna; López-Sánchez, José Fermín; Rubio, Roser; Barbero, Mercedes; Stegen, Susana; Queirolo, Fabrizio; Díaz-Palma, Paula

2013-01-01

136

Bedrock versus alluvial channel geometry  

NASA Astrophysics Data System (ADS)

We present observations of channel geometry obtained on a 524 km long continuous traverse of Fraser River, British Columbia, Canada, as it passes through the Fraser canyons. The channel alternates between gravel-bedded reaches that are incised into semi-consolidated glacial deposits and bedrock-bound reaches (7.7% of the reach above Hope). We obtained data of 71 cross-sections using 600 kHz and 1200 kHz aDcp and, in addition, obtained measures of channel width from Google® imagery at 0.5 km spacing throughout the traverse. To homogenize the data of sectional geometry along the river (to compensate increasing flows at tributary junctions), we computed w/Q^1/2 and d/Q^1/3, following commonly observed scaling relations. For the sounded cross sections Q is the recorded flow at the time of the survey; for the map measurements, Q is mean annual flood for the reach, leading to some difference between the two sets of statistics. From the more abundant map data, alluvial reaches are 2.3x wider than and, from soundings, 0.60 as deep as rock-bound reaches, implying that mean velocity is accelerated in rock reaches by 38%. These data are based on section averages: extremes of depth and velocity in rock canyons are substantially greater. There is also variation from reach to reach along the river controlled by variation in rock lithologies, with the narrowest canyons occurring in Fraser Canyon proper (w/Q^1/2 = 0.083 compared with 1.4 elsewhere). The uppermost ('Marguerite') and lowermost ('Agassiz') alluvial reaches are considerably wider (w/Q^1/2 = 3.9 and 7.1 respectively) than intervening ones (~2.35). These reaches have lower gradients and exhibit wandering channels. Because of lithological control, the downstream hydraulic geometry of the river does not, in fact, conform with the common pattern, even when sections are analyzed according to boundary material. However, river gradient is well correlated with scaled width, inversely for gravel reaches and directly, but with little sensitivity for rock-bound reaches. We show distributions of channel width and depth along the river.

Church, M. A.; Venditti, J. G.; Rennie, C. D.

2012-12-01

137

Miocene to Recent history of the western Altiplano in northern Chile revealed by lacustrine sediments of the Lauca Basin (18°15'-18°40'S/69°30'-69°05'W)  

NASA Astrophysics Data System (ADS)

The intramontane Lauca Basin at the western margin of the northern Chilean Altiplano lies to the west of and is topographically isolated from the well-known Plio-Pleistocene lake system of fluvio-lacustrine origin that covers the Bolivian Altiplano from Lake Titicaca to the north for more than 800km to the Salar de Uyuni in the south. The Lauca Basin is filled by a sequence of some 120m of mainly upper Miocene to Pliocene clastic and volcaniclastic sediments of lacustrine and alluvial origin. Volcanic rocks, partly pyroclastic, provide useful marker horizons. In the first period (6-4Ma) of its evolution, the 'Lago Lauca' was a shallow ephemeral lake. Evaporites indicate temporarily closed conditions. After 4Ma the lake changed to a perennial water body surrounded by alluvial plains. In the late Pleistocene and Holocene (2-0Ma) there was only marginal deposition of alluvial and glacial sediments. The basin formed as a half-graben or by pull-apart between 10 and 15Ma (tectonic displacement of the basal ignimbrite sequence during the 'Quechua Phase') and 6.2Ma (maximum K/Ar ages of biotites of tuff horizons in the deepest part of the basin). Apart from this early basin formation, there has been surprisingly little displacement during the past 6Ma close to the Western Cordillera of the Altiplano. Also, climate indicators (pollen, evaporites, sedimentary facies) suggest that an arid climate has existed for the past 6Ma on the Altiplano. Together, these pieces of evidence indicate the absence of large scale block-faulting, tilt and major uplift during the past 5-6Ma in this area.

Kött, A.; Gaupp, R.; Wörner, G.

138

Miocene to recent history of the western Altiplano in northern Chile revealed by lacustrine sediments of the Lauca basin (18°15' 18°40' S/69°30' 69°05'W)  

NASA Astrophysics Data System (ADS)

The intramontane Lauca Basin at the western margin of the northern Chilean Altiplano lies to the west of and is topographically isolated from the well-known Plio-Pleistocene lake system of fluvio-lacustrine origin that covers the Bolivian Altiplano from Lake Titicaca to the north for more than 800 km to the Salar de Uyuni in the south. The Lauca Basin is filled by a sequence of some 120 m of mainly upper Miocene to Pliocene elastic and volcaniclastic sediments of lacustrine and alluvial origin. Volcanic rocks, partly pyroelastic, provide useful marker horizons. In the first period (6 4 Ma) of its evolution, the ‘Lago Lauca’ was a shallow ephemeral lake. Evaporites indicate temporarily closed conditions. After 4 Ma the lake changed to a perennial water body surrounded by alluvial plains. In the late Pleistocene and Holocene (2-0 Ma) there was only marginal deposition of alluvial and glacial sediments. The basin formed as a half-graben or by pull-apart between 10 and 15 Ma (tectonic displacement of the basal ignimbrite sequence during the ‘Quechua Phase’) and 6.2 Ma (maximum K/Ar ages of biotites of tuff horizons in the deepest part of the basin). Apart from this early basin formation, there has been surprisingly little displacement during the past 6 Ma close to the Western Cordillera of the Altiplano. Also, climate indicators (pollen, evaporites, sedimentary facies) suggest that an arid climate has existed for the past 6 Ma on the Altiplano. Together, these pieces of evidence indicate the absence of large scale block-faulting, tilt and major uplift during the past 5 6 Ma in this area.

Kött, A.; Gaupp, R.; Wörner, G.

1995-12-01

139

Geometry and evolution of a syntectonic alluvial fan, Southern Pyrenees  

SciTech Connect

Syntectonic alluvial fans formed on the northern margin of the Ebro Foreland Basin along the South Pyrenean thrust front during late orogenic thrust movements in the late Oligocene/early Miocene. The present-day geometry, structural relations and sedimentology of one of these fans, the Aguero fan in the province of Huesca, Spain, were studied. Field observations of the architecture of depositional facies and the geometries of syn-tectonic folds and unconformities indicate that the Aguero fan formed as the result of several phases of sedimentation which were primarily controlled by periods of tectonic activity and quiescence. The syntectonic unconformities and growth folds in the fan deposits provide a detailed record of the evolution of a fan adjacent to an active thrust front. Using a computer program to simulate sedimentation and deformation of an alluvial fan it is possible to constrain rates of both sedimentary and tectonic processes by modeling the evolution of the fan body. A facies model for the fan phases indicates that the facies change from proximal (coarse-grained, amalgamated) to distal (finger grained, stacked fining up cycles) in less than 1 km across a fan of radius estimated to be about 2 km.

Arminio, J.F. (Maraven S.A., Caracas (Venezuela)); Nichols, G.J. (Univ. of London, Egham, Surrey (United Kingdom))

1993-02-01

140

Vegetation and carbon sequestration and their relation to water resources in an inland river basin of Northwest China.  

PubMed

In the Heihe River Basin in the arid inland area of northwest China, the distribution of water resources in vegetation landscape zones controls the ecosystems. The carbon sequestration capacity of vegetation is analyzed in relation to water resources and vegetation growing conditions. During the last 20 years, the vegetation ecosystems have degenerated in the Heihe River Basin. Simulation using the C-FIX model indicates that, at present, the total amount of NPP of vegetation accounts for about 18.16 TgC, and the average value is 106 gC/m(2)/yr over the whole basin. NPP has generally the highest value in the upperstream mountain area, middlestream artificial oases area, downstream river bank area, alluvial fan and the terminal lake depression where vegetation grows relatively well. The lowest value is found in the vast downstream desert and Gobi area. Protection of vegetation ecosystems and enhancement of carbon sequestration require such inland river basins as the Heihe River Basin to be brought under management in a comprehensive way, taking water as a key, to carry out a rational and efficient allocation and utilization of water resources. PMID:17126989

Kang, E; Lu, L; Xu, Z

2007-11-01

141

Impacts of hydroelectric dams on alluvial riparian plant communities in Eastern Brazilian Amazonian.  

PubMed

The major rivers of the Amazon River basin and their biota are threatened by the planned construction of large hydroelectric dams that are expected to have strong impacts on floodplain plant communities. The present study presents forest inventories from three floodplain sites colonized by alluvial riparian vegetation in the Tapajós, Xingu and Tocantins River basins in eastern Amazonian. Results indicate that tree species of the highly specialized alluvial riparian vegetation are clearly distinct among the three river basins, although they are not very distinct from each other and environmental constraints are very similar. With only 6 of 74 species occurring in all three inventories, most tree and shrub species are restricted to only one of the rivers, indicating a high degree of local distribution. Different species occupy similar environmental niches, making these fragile riparian formations highly valuable. Conservation plans must consider species complementarily when decisions are made on where to place floodplain forest conservation units to avoid the irreversible loss of unique alluvial riparian vegetation biodiversity. PMID:24068089

Ferreira, Leandro Valle; Cunha, Denise A; Chaves, Priscilla P; Matos, Darley C L; Parolin, Pia

2013-09-01

142

Geological and geochemical characteristics of sedimentary rocks in Kremna, basin (Serbia)  

NASA Astrophysics Data System (ADS)

Studying lacustrine sediments is important because of their potential economic value since they often bear coal, oil shales and non-metallic mineral raw materials. Besides this, lacustrine sediments offer valuable information on the climate conditions which existed during the sedimentation. In Serbia there are 14 lacustrine basins spanning in age from Oligocene to Lower Pliocene. The aim of this study was to examine Lower Miocene Kremna basin, located in southwest Serbia. Kremna basin is a small basin, covering 15km2, but sedimentologically very interesting. For the purpose of this study, 43 sediment samples were taken from a borehole at different depths, from surface to 343 m depth of the basin. The borehole ended in weathered serpentinite. Mineralogical composition of sediments was determined using thin-sections and X-ray diffraction analysis, contents of macro-and microelements and rare-earth elements were determined by ICP-ES and ICP-MS techniques. Also, elemental analysis was applied to determine the contents of carbon, sulphur and nitrogen and n-alkanes, isoprenoide aliphatic alkanes and bitumen were also determined using GC-MS technique. Mineralogical analyses proved presents of several lithological types in Kremna basin: clastic sediments, tuffs, tuffaceous sediments, marlstones, dolomites, magnezites, and coal of non-economic value. Occurrence of sirlezite and sepiolite was also determined. Furthermore, according to all obtained results two faciae were determined: alluvial-marginal lacustrine and intrabasinal. Alluvial-marginal facies originated from predominantly ultramafic rocks which underlie the basin. Magnezites and Mg-marls and Mg-dolomites are dominant sediments in this facies. These sediments formed under arid, slightly saline conditions. Intrabasinal facies is represented mostly with marls, Mg-marls and dolomitic limestones. These sediments were deposited under a more humid climate with increase in paleoproductivity. The uppermost sediments of Kremna basin are represented with marly dolomite. Due to the swallowing of the basin sediments became relatively rich in predominantly land plant material. Tuffs and tuffaceous sediments were determined in both faciae.

Perunovi?, Tamara; Jovan?i?evi?, Branimir; Br?eski, Ilija; Šajnovi?, Aleksandra; Stojanovi?, Ksenija; Simi?, Vlada; Kašanin-Grubin, Milica

2014-05-01

143

Investigation of groundwater response to overland flow and topography using a coupled MIKE SHE\\/MIKE 11 modeling system for an arid watershed  

Microsoft Academic Search

The distribution of groundwater and dynamic fluctuations in groundwater levels have direct impacts on the eco-environment of arid areas. Investigations of groundwater recharge in arid areas are typically limited by a lack of adequate meteorological and hydrogeological records. This study focuses on groundwater recharge in a seasonally flooded arid area within the Tarim Basin, China, with the aim of analyzing

Hai-Long Liu; Xi Chen; An-Ming Bao; Ling Wang

2007-01-01

144

Morphodynamic equilibrium of alluvial estuaries  

NASA Astrophysics Data System (ADS)

The evolution of the longitudinal bed profile of an estuary, with given plan-form configuration, subject to given tidal forcing at the mouth and prescribed values of water and sediment supply from the river is investigated numerically. Our main goal is to ascertain whether, starting from some initial condition, the bed evolution tends to reach a unique equilibrium configuration asymptotically in time. Also, we investigate the morphological response of an alluvial estuary to changes in the tidal range and hydrologic forcing (flow and sediment supply). Finally, the solution helps characterizing the transition between the fluvially dominated region and the tidally dominated region of the estuary. All these issues play an important role also in interpreting how the facies changes along the estuary, thus helping to make correct paleo-environmental and sequence-stratigraphic interpretations of sedimentary successions (Dalrymple and Choi, 2007). Results show that the model is able to describe a wide class of settings ranging from tidally dominated estuaries to fluvially dominated estuaries. In the latter case, the solution is found to compare satisfactory with the analytical asymptotic solution recently derived by Seminara et al. (2012), under the hypothesis of fairly 'small' tidal oscillations. Simulations indicate that the system always moves toward an equilibrium configuration in which the net sediment flux in a tidal cycle is constant throughout the estuary and equal to the constant sediment flux discharged from the river. For constant width, the bed equilibrium profile of the estuarine channel is characterized by two distinct regions: a steeper reach seaward, dominated by the tide, and a less steep upstream reach, dominated by the river and characterized by the undisturbed bed slope. Although the latter reach, at equilibrium, is not directly affected by the tidal wave, however starting from an initial uniform stream with the constant 'fluvial' slope, the final equilibrium state is reached through an erosional wave, which leads to bed degradation of the upstream 'fluvial reach'. For a given river discharge, the length of the tidal reach increases quite rapidly with tidal amplitude, up to some threshold value of the tidal amplitude above which the length of the estuary becomes comparable with the length of the tidal wave. When the channel plan-form is convergent, deposition of sediments of fluvial origin in the funnel-shaped region drastically changes the equilibrium configuration. The effect of an increasing channel convergence is thus to induce bed aggradation close to the inlet. Nevertheless, tidal forcing only slightly changes the non-tidal profile. The effect of increasing tidal oscillations again leads to an increase of the bed slope at the inlet and to a general bed degradation upstream. The effects of varying sediment supply, flow discharge and river width in the upstream reach have also been investigated and play an important role. Further geomorphological implications of these results will be discussed at the meeting. References Dalrymple, R. W., and K. Choi (2007), Morphologic and facies trends through the fluvialmarine transition in tide-dominated depositional systems: A schematic framework for environmental and sequence-stratigraphic interpretation, Earth-Science Reviews, 81(3-4), 135-174, doi:10.1016/j.earscirev.2006.10.002. Seminara, G., M. Bolla Pittaluga, and N. Tambroni (2012), Morphodynamic equilibrium of tidal channels, Environmental Fluid Mechanics: Memorial Volume in Honour of Prof. Gerhard H. Jirka, 153-174

Tambroni, Nicoletta; Bolla Pittaluga, Michele; Canestrelli, Alberto; Lanzoni, Stefano; Seminara, Giovanni

2014-05-01

145

Luminescence ages for alluvial-fan deposits in Southern Death Valley: Implications for climate-driven sedimentation along a tectonically active mountain front  

USGS Publications Warehouse

Controversy exists over whether alluvial-fan sedimentation along tectonically active mountain fronts is driven by climatic changes or tectonics. Knowing the age of sedimentation is the key to understanding the relationship between sedimentation and its cause. Alluvial-fan deposits in Death Valley and throughout the arid southwestern United States have long been the subjects of study, but their ages have generally eluded researchers until recently. Most mapping efforts have recognized at least four major relative-age groupings (Q1 (oldest), Q2, Q3, and Q4 (youngest)), using observed changes in surface soils and morphology, relation to the drainage net, and development of desert pavement. Obtaining numerical age determinations for these morphologic stages has proven challenging. We report the first optically stimulated luminescence (OSL) ages for three of these four stages deposited within alluvial-fans along the tectonically active Black Mountains of Death Valley. Deposits showing distinct, remnant bar and swale topography (Q3b) have OSL ages from 7 to 4 ka., whereas those with moderate to poorly developed desert pavement and located farther above the active channel (Q3a) have OSL ages from 17 to 11 ka. Geomorphically older deposits with well-developed desert pavement (Q2d) have OSL ages ???25 ka. Using this OSL-based chronology, we note that alluvial-fan deposition along this tectonically active mountain front corresponds to both wet-to-dry and dry-to-wet climate changes recorded globally and regionally. These findings underscore the influence of climate change on alluvial fan deposition in arid and semi-arid regions. ?? 2007 Elsevier Ltd and INQUA.

Sohn, M. F.; Mahan, S. A.; Knott, J. R.; Bowman, D. D.

2007-01-01

146

Spatial patterns of ecohydrologic properties on a hillslope-alluvial fan transect, central New Mexico  

USGS Publications Warehouse

Spatial patterns of soil properties are linked to patchy vegetation in arid and semi-arid landscapes. The patterns of soil properties are generally assumed to be linked to the ecohydrological functioning of patchy dryland vegetation ecosystems. We studied the effects of vegetation canopy, its spatial pattern, and landforms on soil properties affecting overland flow and infiltration in shrublands at the Sevilleta National Wildlife Refuge/LTER in central New Mexico, USA. We studied the patterns of microtopography and saturated conductivity (Ksat), and generally found it to be affected by vegetation canopy and pattern, as well as landform type. On gently sloping alluvial fans, both microtopography and Ksat are high under vegetation canopy and decay with distance from plant center. On steeper hillslope landforms, only microtopography was significantly higher under vegetation canopy, while there was no significant difference in Ksat between vegetation and interspaces. Using geostatistics, we found that the spatial pattern of soil properties was determined by the spatial pattern of vegetation. Most importantly, the effects of vegetation were present in the unvegetated interspaces 2-4 times the extent of vegetation canopy, on the order of 2-3??m. Our results have implications for the understanding the ecohydrologic function of semi-arid ecosystems as well as the parameterization of hydrologic models. ?? 2007 Elsevier B.V. All rights reserved.

Bedford, D.R.; Small, E.E.

2008-01-01

147

Channel form and processes in bedrock and alluvial reaches of the Raritan River, New Jersey  

NASA Astrophysics Data System (ADS)

Fluvial geomorphologists have generally considered alluvial and bedrock channels to be fundamentally different in character, alluvial channels being shaped by sediment-transport processes and bedrock channels being shaped by structural and lithologic controls. This study examines a 12-km bedrock-floored reach of the Raritan River that separates two gravel-bed reaches, above and below. The bedrock channel has a patchy veneer of sandy gravel that covers the bed in areas of low slope but elsewhere consists of lateral bars and discrete, two-dimensional gravel bed forms perched on bedrock. Mean B-axes of the 25 largest clasts on the crests of these bed forms range from 10.4 to 13.8 cm. Shear stresses estimated from measured velocity profiles and depth-slope calculations indicate that most clasts on the bed forms are entrained by the bankfull discharge (290 m/s) which is equaled or exceeded about 1%of the time. The thalweg of the 80-m-wide channel is incised about 0.5 to 0.7 m, and it meanders with a wavelength of about 750 m, or approximately 10 times channel width. This thalweg meander wavelength is consistent with reference to drainage area when compared to channel meander wavelengths in other locations within the basin and is similar to that in other rivers of comparable dimensions and discharge. The bedrock-alluvial reach is similar to alluvial channels with reference to meander geometry and sediment distribution. It occupies an intermediate position on a continuum of channels-of varying sediment supply in relation to transport capacity, ranging from alluvial channels to those completely formed in bedrock.

Ashley, Gail M.; Renwick, William H.; Haag, Gary H.

1988-05-01

148

Downstream effects of dams on alluvial rivers  

Microsoft Academic Search

This study describes changes in mean channel-bed elevation, channel width, bed-material sizes, vegetation, water discharges, and sediment loads downstream from 21 dams constructed on alluvial rivers. Most of the studied channels are in the semiarid western US. Flood peaks generally were decreased by the dams, but in other respects the post-dam water-discharge characteristics varied from river to river. Sediment concentrations

G. P. Williams; M. G. Wolman

1985-01-01

149

Fertilizers mobilization in alluvial aquifer: laboratory experiments  

Microsoft Academic Search

In alluvial plains, intensive farming with conspicuous use of agrochemicals, can cause land pollution and groundwater contamination.\\u000a In central Po River plain, paleo-channels are important links between arable lands and the underlaying aquifer, since the\\u000a latter is often confined by clay sediments that act as a barrier against contaminants migration. Therefore, paleo-channels\\u000a are recharge zones of particular interest that have

M. Mastrocicco; N. Colombani; S. Palpacelli

2009-01-01

150

The application of remotely sensed data to pedologic and geomorphic mapping on alluvial fan and playa surfaces in Saline Valley, California  

NASA Technical Reports Server (NTRS)

Arid and semiarid regions yield excellent opportunities for the study of pedologic and geomorphic processes. The dominance of rock and soil exposure over vegetation not only provides the ground observer with observational possibilities but also affords good opportunities for measurement by aircraft and satellite remote sensor devices. Previous studies conducted in the area of pedologic and geomorphic mapping in arid regions with remotely sensed data have utilized information obtained in the visible to near-infrared portion of the spectrum. Thermal Infrared Multispectral Scanner (TIMS) and Thematic Mapping (TM) data collected in 1984 are being used in comjunction with maps compiled during a Bureau of Land Management (BLM) soil survey to aid in a detailed mapping of alluvial fan and playa surfaces within the valley. The results from this study may yield valuable information concerning the application of thermal data and thermal/visible data combinations to the problem of dating pedologic and geomorphic features in arid regions.

Miller, D. A.; Petersen, G. W.; Kahle, A. B.

1986-01-01

151

Chronology of the late Turolian deposits of the Fortuna basin (SE Spain): implications for the Messinian evolution of the eastern Betics  

Microsoft Academic Search

The magnetostratigraphy of the mammal-bearing alluvial fan–fan delta sequences of the Fortuna basin (SE Spain) has yielded an accurate chronology for the late Turolian (Messinian) basin infill. From early to late Messinian (at least between 6.8 and 5.7 Ma), the Fortuna basin records the sedimentation of alluvial–palustrine deposits over a confined shallow basin. Changing environmental conditions in the latest Messinian

Miguel Garcés; Wout Krijgsman; Jorge Agust??

1998-01-01

152

Development and lithogenesis of the palustrine and calcrete deposits of the Dibdibba Alluvial Fan, Kuwait  

NASA Astrophysics Data System (ADS)

A model is proposed for the development of the Quaternary palustrine carbonate-calcrete association, which occurs as hard crust capping low hills at a distal flood plain of Al Dibdibba alluvial fan located at southwestern Kuwait. Field occurrence, detailed petrographic investigation and geochemical analysis revealed that a single cycle of groundwater calcrete with vertical gradational maturity pattern was developed. This represents a continuous sedimentological cycle during which flood sheet conditions prevailed with intermittent periods of humid and arid conditions. Subsequently, calcitic micrite was continuously precipitated from small, shallow, local, isolated and short lived ponds fringed by freshwater marshes with abundant charophyte meadows. The latter were developed as a result of flooding scattered depressions by groundwater supersaturated with respect to calcite due to rise of groundwater table. The deposition of two facies of carbonate muds, namely; biomicrite and pelintraclasts skeletal micrites was followed by a drought phase which witnessed desiccation of the fresh water ponds and significant drop in groundwater level. A sequence of pedogenic and diagenetic processes acted on the deposited carbonate muds are manifested by: (a) desiccation cracks, (b) micrite neomorphism, (c) infilling of root burrows and some cracks by aeolian siliciclastics, (d) karstification, (e) marmorization, (f) calcretization of root burrow infill and development of pseudo-rhizocrete, (g) calcite cementation and mineral authigenesis, and (h) silcretization. These processes are responsible for the development of hard palustrine carbonate crust. At the advent of aridity, the whole system of Al Dibdibba alluvial fan was subjected to deflation. This resulted in reversing the paleotopography of the hard crusted palustrine depressions into carbonate capped domal hills.

AlShuaibi, Arafat A.; Khalaf, Fikry I.

2011-08-01

153

Late Quaternary eolian and alluvial response to paleoclimate, Canyonlands, southeastern Utah  

USGS Publications Warehouse

In upland areas of Canyonlands National Park, Utah, thin deposits and paleosols show late Quaternary episodes of eolian sedimentation, pedogenesis, and climate change. Interpretation of the stratigraphy and optically stimulated luminescence ages of eolian and nearby alluvial deposits, their pollen, and intercalated paleosols yields the following history: (1) Eolian deposition at ca. 46 ka, followed by several episodes of alluviation from some time before ca. 40 ka until after 16 ka (calibrated). (2) Eolian deposition from ca. 17 ka to 12 ka, interrupted by periods of pedogenesis, coinciding with late Pleistocene alluviation as local climate became warmer and wetter. (3) A wetter period from 12 to 8.5 ka corresponding to the peak of summer monsoon influence, during which soils formed relatively quickly by infiltration of eolian silt and clay, and trees and grasses were more abundant. (4) A drier period between ca. 8.5 and 6 ka during which sheetwash deposits accumulated and more desertlike vegetation was dominant; some dunes were reactivated at ca. 8 ka. (5) Episodic eolian and fluvial deposition during a wetter, cooler period that began at ca. 6 ka and ended by ca. 3-2 ka, followed by a shift to drier modern conditions; localized mobilization of dune sand has persisted to the present. These interpretations are similar to those of studies at the Chaco dune field, New Mexico, and the Tusayan dune field, Arizona, and are consistent with paleoclimate interpretations of pollen and packrat middens in the region. A period of rapid deposition and infiltration of eolian dust derived from distant igneous source terranes occurred between ca. 12 and 8 ka. Before ca. 17 ka, and apparently back to at least 45 ka, paleosols contain little or no such infiltrated dust. After ca. 8 ka, either the supply of dust was reduced or the more arid climate inhibited translocation of dust into the soils. ?? 2005 Geological Society of America.

Reheis, M. C.; Reynolds, R. L.; Goldstein, H.; Roberts, H. M.; Yount, J. C.; Axford, Y.; Cummings, L. S.; Shearin, N.

2005-01-01

154

Fluoride distribution in water and the governing factors of environment in arid north-west China  

Microsoft Academic Search

In arid areas of north-west China, fluorides occur predominantly as NaF and KF. They are fairly ubiquitous in both natural surface waters such as rivers, lakes and reservoirs, and in ground-water. Abundant fluoride sources, a relatively closed hydrological network, and the dry climate of the arid inland basin provide favorable conditions to the dissolution, migration and enrichment of fluoride. The

Wang Genxu; Cheng Guodong

2001-01-01

155

Semi-Arid Land-Surface-Atmosphere (SALSA) Program  

NSDL National Science Digital Library

The Semi-Arid Land-Surface-Atmosphere (SALSA) Program is "a multi-agency, multi-national global-change research effort that seeks to evaluate the consequences of natural and human-induced changes in semi-arid environments." Current research efforts focus on the upper San Pedro River basin, encompassing southeastern Arizona and northeastern Sonora (Mexico). At the site, users will find summaries of current research in the Research section, including study area maps and project summaries for the Transborder Watershed Research Program, Ecosystem Fragmentation and Restoration Study, the 1998 Mexico Campaign (an intensive field campaign "to measure upland water and energy fluxes during August and September 1998"), and Riparian Ecophysiology (coming soon). Also available are numerous archived summaries from research conducted before 1998. An excellent collection of links on global change research and "other information sources related to the hydrology and ecology of the Upper San Pedro River Basin" rounds out the site.

156

Fire, climate, and alluvial system dynamics: A Holocene record from Yellowstone National Park  

SciTech Connect

Many large debris-flow, hyperconcentrated-flow, and flood-streamflow sediment transport events have been produced in steep basins that were burned in the 1988 fires in northeaster Yellowstone National Park. The charcoal- and fines-rich character of fire-related debris-flow deposits and the abundance of similar facies in Holocene fan sections have allowed them to construct a [sup 14]C-dated chronology of fire-related sedimentation in the Soda Butte and Slough Creek drainages for the last 3500 years. Major periods of fire-related alluvial fan aggradation are interpreted as drought-dominated with the support of local paleoenvironmental data and statistical analyses of historical climate-fire relations; however, some fire-related events may occur due to high climatic variability and severe short-term drought within generally moist intervals. The last major episode of fire-related debris-flow activity encompasses the Medieval Warm Period of 900--1300 AD and peaks ca. 1150 AD; a prior episode culminates ca. 350--100 BC. Wetter periods contain minimal fire-related fan sedimentation; however, floodplain broadening and aggradation occurs along axial streams. Higher average snowmelt runoff discharges are probably involved, such that the dominant alluvial activity shifts to removal of sediment from alluvial fan storage and transport to downstream floodplains. The Little Ice Age (ca. 1300--1900 AD) contains minimal fire-related debris0flow activity and is associated with floodplain aggradation of the T4 terrace, and independent evidence suggests substantially wetter conditions during T3 aggradation ca. 350--650 AD. Thus, small-scale climate changes of the late Holocene effectively control the dominant mode of alluvial activity.

Meyer, G.A. (Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Geology); Wells, S.G. (Univ. of California, Riverside, CA (United States). Dept. of Earth Sciences); Jull, A.J. (Univ. of Arizona, Tucson, AZ (United States). NSF-Arizona Accelerator Facility For Isotope Dating)

1992-01-01

157

The volcano-sedimentary evolution of a post-Variscan intramontane basin in the Swiss Alps (Glarus Verrucano) as revealed by zircon U-Pb age dating and Hf isotope geochemistry  

NASA Astrophysics Data System (ADS)

The Late Palaeozoic Glarus Verrucano basin (GVB, Glarus Alps, eastern Switzerland) formed as an intramontane graben in the aftermath of the Variscan orogeny. Its fill, the Glarus Verrucano, consists of immature alluvial fan and playa lake deposits with intercalated bimodal volcanics (basalts and rhyolites). Despite its importance for local and regional geology, no modern sedimentologic or stratigraphic studies on the GVB exist. By means of sedimentologic and geochronologic studies, we reconstruct the volcano-sedimentary evolution of the GVB: it developed at the Carboniferous/Permian boundary and experienced a first (bimodal) volcanic phase around 285 Ma. For the same time, indications for temporarily humid climate in the otherwise rather arid Early Permian are demonstrated (e.g. pyrite-bearing sandstones). During the Middle and Early Late Permian, increasing aridity is indicated by playa deposits, fanglomerates and subaerial ignimbrites, which mark a second (silicic) volcanic phase at 268 Ma. The detrital zircon age spectra are dominated by Late Variscan ages and thus demonstrate that older sedimentary and metamorphic rocks once forming the Variscan nappe edifice were already mostly eroded at that time. Finally, some larger-scale speculations are given which could indicate a causal connection between the widespread tectono-magmatic Mid-Permian Episode and the local development of the Glarus Verrucano basin.

Letsch, Dominik; Winkler, Wilfried; von Quadt, Albrecht; Gallhofer, Daniela

2014-07-01

158

Fertilizers mobilization in alluvial aquifer: laboratory experiments  

NASA Astrophysics Data System (ADS)

In alluvial plains, intensive farming with conspicuous use of agrochemicals, can cause land pollution and groundwater contamination. In central Po River plain, paleo-channels are important links between arable lands and the underlaying aquifer, since the latter is often confined by clay sediments that act as a barrier against contaminants migration. Therefore, paleo-channels are recharge zones of particular interest that have to be protected from pollution as they are commonly used for water supply. This paper focuses on fertilizer mobilization next to a sand pit excavated in a paleo-channel near Ferrara (Italy). The problem is approached via batch test leaking and columns elution of alluvial sediments. Results from batch experiments showed fast increase in all major cations and anions, suggesting equilibrium control of dissolution reactions, limited availability of solid phases and geochemical homogeneity of samples. In column experiments, early elution and tailing of all ions breakthrough was recorded due to preferential flow paths. For sediments investigated in this study, dispersion, dilution and chemical reactions can reduce fertilizers at concentration below drinking standards in a reasonable time frame, provided fertilizer loading is halted or, at least, reduced. Thus, the definition of a corridor along paleo-channels is recommended to preserve groundwater quality.

Mastrocicco, M.; Colombani, N.; Palpacelli, S.

2009-02-01

159

Sedimentology and palaeontology of the Upper Jurassic Puesto Almada Member (Cañadón Asfalto Formation, Fossati sub-basin), Patagonia Argentina: Palaeoenvironmental and climatic significance  

NASA Astrophysics Data System (ADS)

Six facies associations are described for the Puesto Almada Member at the Cerro Bandera locality (Fossati sub-basin). They correspond to lacustrine, palustrine, and pedogenic deposits (limestones); and subordinated alluvial fan, fluvial, aeolian, and pyroclastic deposits. The lacustrine-palustrine depositional setting consisted of carbonate alkaline shallow lakes surrounded by flooded areas in a low-lying topography. The facies associations constitute four shallowing upward successions defined by local exposure surfaces: 1) a Lacustrine-Palustrine-pedogenic facies association with a 'conchostracan'-ostracod association; 2) a Palustrine facies association representing a wetland subenvironment, and yielding 'conchostracans', body remains of insects, fish scales, ichnofossils, and palynomorphs (cheirolepidiacean species and ferns growing around water bodies, and other gymnosperms in more elevated areas); 3) an Alluvial fan facies association indicating the source of sediment supply; and 4) a Lacustrine facies association representing a second wetland episode, and yielding 'conchostracans', insect ichnofossils, and a palynoflora mainly consisting of planktonic green algae associated with hygrophile elements. The invertebrate fossil assemblage found contains the first record of fossil insect bodies (Insecta-Hemiptera and Coleoptera) for the Cañadón Asfalto Formation. The succession reflects a mainly climatic control over sedimentation. The sedimentary features of the Puesto Almada Member are in accordance with an arid climatic scenario across the Upper Jurassic, and they reflect a strong seasonality with periods of higher humidity represented by wetlands and lacustrine sediments.

Cabaleri, Nora G.; Benavente, Cecilia A.; Monferran, Mateo D.; Narváez, Paula L.; Volkheimer, Wolfgang; Gallego, Oscar F.; Do Campo, Margarita D.

2013-10-01

160

Simulating Fine grained Alluvial Fan Sedimentation on Mars  

NASA Astrophysics Data System (ADS)

The alluvial fans on Mars date to as late as the Hesperian Period and may be representative of the last major episode of widespread fluvial modification to the red planet's surface. These fans lie within enclosed crater basins, and are characterized by their large size (tens of km in length) and gentle gradient (less than 1-3°). The fans generally feature a network of channel distributaries floored with coarser sediment and what we have interpreted to be fine grained overbank deposits that comprise the bulk of the fan material [1]. We have developed a landform evolution model based on the approach of [2] to simulate the growth of these fans in order to answer several questions about their formation, including: (1) what are the characteristics of water discharge (flow magnitude and duration) and sediment supply (quantity and grain size); and (2) what are the associated implications for the responsible climatic environment (e.g. amount and frequency of precipitation sourcing the fans). The model combines discharge and sediment deposition with channel avulsion and abandonment, allowing for an analysis of both the micro and macro scale processes concerning fan formation. Water and sediment is routed through a distributary network that can branch, recombine, and avulse. The model simulates deposition of both coarse-grained bedload and a fine-grained suspended load material that can be deposited overbank during flood events. The model records the stratigraphy of the deposited material in terms of the relative proportions of coarse and fine-grained sediment. Using measures such as channel width, relative proportions of channel versus overbank deposited sediment, and frequency of channel branching, output is statistically compared with digital elevation models that have been produced from high-resolution CTX and HiRISE stereo pairs. Initial results suggest fans formed from hundreds of flow events over many thousands of years. Fan formation processes appear to be similar to those active in terrestrial fans in northern Chile's Atacama Desert. Additional model runs will simulate fan development under different patterns of precipitation (uniform over the fan versus an orographic pattern of greater precipitation on upper crater walls) and variations in sediment size distribution. References: [1] Morgan, A. M., Howard, A. D., Hobley, D. E. J., Moore, J. M., Dietrich, W. E., Williams, R. M. E., Burr, D. M., Grant, J. A., Wilson, S. A., and Matsubara, Y. (in review) Sedimentology and Climatic Environment of Alluvial Fans in the Martian Saheki Crater and a Comparison with Terrestrial Fans in the Atacama Desert [2] Sun, T., C. Paola, G. Parker, and P. Meakin (2002), Water Resour. Res., 38, no.8, 10.

Morgan, A. M.; Howard, A. D.; Moore, J. M.; Beyer, R. A.

2013-12-01

161

Modelling the distribution of detrital cosmogenic nuclide concentrations: a new tool to study drainage basin evolution.  

NASA Astrophysics Data System (ADS)

Cosmogenic nuclide concentrations (CNCs) in alluvial sediments are now routinely being used to estimate time- and space-averaged drainage basin denudation rates but have the potential to offer considerably more. This is because each grain leaving a drainage basin has a potentially unique history of erosion, transport and storage, meaning that the distribution of CNCs in large numbers of grains can provide an integrated signature of the basin's geomorphic history. We use a numerical model describing cosmogenic nuclide acquisition in sediments moving through an arid- zone drainage basin to explore the sensitivity of alluvial CNC distributions to assumptions about the geomorphic settings of the sediment's source areas. The model fully accounts for variations in nuclide production due to changes in latitude, altitude and topographic shielding and allows for spatially variable erosion and sediment transport rates. Data for model validation are provided by measurements of cosmogenic 21Ne concentrations in 32 16-22 mm diameter quartzite clasts from a 200 m reach of the Gaub river (a tributary of the Kuiseb, Namibia) along with measurements of cosmogenic 10Be in 12 amalgamated fluvial sediment samples from the outlets of the Gaub's tributaries. Model results show that detrital CNC distributions are highly sensitive to the geomorphic settings of the sediments' source areas and have the potential to be able to differentiate tectonic settings and/or geomorphic histories. The clast 21Ne concentrations vary between 2.6×106 and 1.6×108 atoms/g and exhibit a non-Gaussian distribution. The shape of this distribution, also predicted by the model, confirms the non-random nature of detrital CNC acquisition. These results also emphasise the importance of the assumptions made when using cosmogenic nuclides to estimate basin-wide denudation rates. The non- Gaussian distribution shows that the assumption of random inheritance of CNCs in the sediments cannot always be made, such that there may be scope for using this method for a priori estimates of inheritance that can be used in dating sedimentary deposits.

Codilean, A. T.; Hoey, T. B.; Bishop, P.; Stuart, F. M.; Fabel, D.; Willgoose, G. R.

2006-12-01

162

Alluvial Fan Records of Climatically Driven Changes in Hillslope Eerosion Rates: Successes, Limitations, and Future Directions  

NASA Astrophysics Data System (ADS)

The erosional response of semi-arid landscapes to changes in the frequency and intensity of precipitation is poorly understood. Some have argued that hillslope erosion rates are greater when precipitation is dominated by short-duration, high-intensity events that generate intense overland flow on poorly vegetated hillslopes, whereas others have suggested that hillslope erosion and sediment transport rates are greater when precipitation is dominated by long-duration, low-intensity events due to higher rates of sediment production on hillslopes and sustained stream discharge. Both of these models suggest that hillslope erosion rates will vary as a function of the relative balance of low-intensity, long-duration (e.g., winter frontal storms) to high-intensity, short-duration (e.g., monsoons and convective storms) precipitation. Variations in hillslope erosion rates should affect sediment supply to alluvial fan heads, and so the timing and magnitude of fan head depositional events may provide a record of temporal changes in the style of precipitation. Preliminary depositional ages, interpreted from new cosmogenic 10Be measurements, are combined with existing soils, sedimentologic, and existing 10Be data from an alluvial fan head in the semi-arid Providence Mountains, eastern Mojave Desert, CA, to test this hypothesis. The Providence Mountains expose Proterozoic gneisses and Mesozoic granites and show no evidence of Quaternary faulting, indicating that Pleistocene fan complexes exposed at the mountain front are primarily climatically driven. Erosion rates determined from 10Be concentrations in active wash sediments vary from 33.27 ± 1.20 to 62.40 ± 1.40 m/My and show no apparent relation to grain size. Additionally, soil stratigraphic observations from a 5.5 m thick alluvial package exposed in the fan head include a ~70 cm thick stage IV calcic horizon that is cross cut by a ~3 m deep paleochannel, which contains at least four separate soils. The paleochannel is overlain by a laterally continuous deposit possessing a Bt horizon, a capping Av, and moderately developed pavement that, based on microlamination stratigraphy, is at least 56 ky old. These observations, combined with preliminary 10Be interpretations, indicate that the top of the older alluvial sequence, which contains the stage IV calcic horizon, is at least 375 ka. Using this limiting age, two end-member models for the depositional history of the alluvial sequence, and our observations of soil development elsewhere in the region, we can use several different methods to arrive at the paleoerosion rates at the time of deposition of the oldest stratigraphic interval. These rates are between ~25 and ~135 m/My or between ~30 and ~850 m/My, depending on the preferred age model and interpretive method. Although the lack of tighter age control does not allow us to establish whether faster paleoerosion rates are the result of periods of dominantly more or less intense precipitation, our results do demonstrate that erosion rates may have varied by up to an order of magnitude through time. Perhaps more importantly, even though the results are broadly similar in this case, it appears that it is possible for one to arrive at completely different answers to the same question depending on how the cosmogenic nuclide data are interpreted.

Cyr, A. J.; Miller, D. M.; Reheis, M. C.

2012-12-01

163

Debris-flow dominance of alluvial fans masked by runoff reworking and weathering  

NASA Astrophysics Data System (ADS)

Arid alluvial fan aggradation is highly episodic and fans often comprise active and inactive sectors. Hence the morphology and texture of fan surfaces are partly determined by secondary processes of weathering and erosion in addition to primary processes of aggradation. This introduces considerable uncertainty in the identification of formative processes of terrestrial and Martian fans from aerial and satellite imagery. The objectives of this study are (i) to develop a model to describe the sedimentological and morphological evolution of inactive fan surfaces in arid settings, and (ii) to assess the relative importance of primary processes of aggradation and secondary processes of weathering and reworking for surface morphology and sedimentology and for the stratigraphic record. We studied an alluvial fan characterized by a recently active sector and a long-abandoned, inactive sector along the coast of the hyperarid Atacama Desert. Here, rates of primary geomorphic activity are exceptionally low because of extreme aridity, while weathering rates are relatively high because of the effects of coastal fogs. Long-term processes of fan aggradation and reworking were determined through sedimentological facies analysis of stratigraphic sections. Ground surveys for textural and morphological patterns at the fan surface were integrated with remote-sensing by an Unmanned Airborne Vehicle (UAV). Discharges and sediment-transport capacities were calculated to estimate the efficiency of secondary runoff in reshaping the inactive fan sector. Stratigraphic sections reveal that the fan was dominantly aggraded by debris flows, whereas surface morphology is dominated by debris-flow signatures in the active sector and by weathering and runoff on the inactive sector. On the latter, rapid particle breakdown prevents the formation of a coarse desert pavement. Furthermore, relatively frequent local runoff events erode proximal debris-flow channels on the inactive sector to form local lag deposits and accumulate fine sediment in low-gradient distal channels, forming a well-developed drainage pattern that would suggest a runoff origin from aerial images. Nevertheless, reworking is very superficial and barely preserved in the stratigraphic record. This implies that fans on Earth and Mars that formed dominantly by sporadic mass flows may be masked by a surface morphology related to other processes.

de Haas, Tjalling; Ventra, Dario; Carbonneau, Patrice E.; Kleinhans, Maarten G.

2014-07-01

164

Combining point and distributed snowpack data with landscape-based discretization for hydrologic modeling of the snow-dominated Maipo River basin, in the semi-arid Andes of Central Chile.  

NASA Astrophysics Data System (ADS)

The 5000-km2 upper Maipo River Basin, in central Chile's Andes, has an adequate streamgage network but almost no meteorological or snow accumulation data. Therefore, hydrologic model parameterization is strongly subject to model errors stemming from input and model-state uncertainty. In this research, we apply the Cold Regions Hydrologic Model (CRHM) to the basin, force it with reanalysis data downscaled to an appropriate resolution, and inform a parsimonious basin discretization, based on the hydrologic response unit concept, with distributed data on snowpack properties obtained through snow surveys for two seasons. With minimal calibration the model is able to reproduce the seasonal accumulation and melt cycle as recorded in the one snow pillow available for the basin, and although a bias in maximum accumulation persists, snowpack persistence in time is appropriately simulated based on snow water equivalent and snow covered area observations. Blowing snow events were simulated by the model whenever daily wind speed surpassed 8 m/s, although the use of daily instead of hourly data to force the model suggests that this phenomenon could be underestimated. We investigate the representation of snow redistribution by the model, and compare it with small-scale observations of wintertime snow accumulation on glaciers, in a first step towards characterizing ice distribution within a HRU spatial discretization. Although built at a different spatial scale, we present a comparison of simulated results with distributed snow depth data obtained within a 40 km2 sub-basin of the main Maipo watershed in two snow surveys carried out at the end of winter seasons 2011 and 2012, and compare basin-wide SWE estimates with a regression tree extrapolation of the observed data.

McPhee, James; Videla, Yohann

2014-05-01

165

Movement of water infiltrated from a recharge basin to wells  

USGS Publications Warehouse

Local surface water and stormflow were infiltrated intermittently from a 40-ha basin between September 2003 and September 2007 to determine the feasibility of recharging alluvial aquifers pumped for public supply, near Stockton, California. Infiltration of water produced a pressure response that propagated through unconsolidated alluvial-fan deposits to 125 m below land surface (bls) in 5 d and through deeper, more consolidated alluvial deposits to 194 m bls in 25 d, resulting in increased water levels in nearby monitoring wells. The top of the saturated zone near the basin fluctuates seasonally from depths of about 15 to 20 m. Since the start of recharge, water infiltrated from the basin has reached depths as great as 165 m bls. On the basis of sulfur hexafluoride tracer test data, basin water moved downward through the saturated alluvial deposits until reaching more permeable zones about 110 m bls. Once reaching these permeable zones, water moved rapidly to nearby pumping wells at rates as high as 13 m/d. Flow to wells through highly permeable material was confirmed on the basis of flowmeter logging, and simulated numerically using a two-dimensional radial groundwater flow model. Arsenic concentrations increased slightly as a result of recharge from 2 to 6 ?g/L immediately below the basin. Although few water-quality issues were identified during sample collection, high groundwater velocities and short travel times to nearby wells may have implications for groundwater management at this and at other sites in heterogeneous alluvial aquifers.

O'Leary, David R.; Izbicki, John A.; Moran, Jean E.; Meeth, Tanya; Nakagawa, Brandon; Metzger, Loren; Bonds, Chris; Singleton, Michael J.

2012-01-01

166

Movement of water infiltrated from a recharge basin to wells.  

PubMed

Local surface water and stormflow were infiltrated intermittently from a 40-ha basin between September 2003 and September 2007 to determine the feasibility of recharging alluvial aquifers pumped for public supply, near Stockton, California. Infiltration of water produced a pressure response that propagated through unconsolidated alluvial-fan deposits to 125 m below land surface (bls) in 5 d and through deeper, more consolidated alluvial deposits to 194 m bls in 25 d, resulting in increased water levels in nearby monitoring wells. The top of the saturated zone near the basin fluctuates seasonally from depths of about 15 to 20 m. Since the start of recharge, water infiltrated from the basin has reached depths as great as 165 m bls. On the basis of sulfur hexafluoride tracer test data, basin water moved downward through the saturated alluvial deposits until reaching more permeable zones about 110 m bls. Once reaching these permeable zones, water moved rapidly to nearby pumping wells at rates as high as 13 m/d. Flow to wells through highly permeable material was confirmed on the basis of flowmeter logging, and simulated numerically using a two-dimensional radial groundwater flow model. Arsenic concentrations increased slightly as a result of recharge from 2 to 6 µg/L immediately below the basin. Although few water-quality issues were identified during sample collection, high groundwater velocities and short travel times to nearby wells may have implications for groundwater management at this and at other sites in heterogeneous alluvial aquifers. PMID:21740423

O'Leary, David R; Izbicki, John A; Moran, Jean E; Meeth, Tanya; Nakagawa, Brandon; Metzger, Loren; Bonds, Chris; Singleton, Michael J

2012-01-01

167

Causes of farmland salinization and remedial measures in the Aral Sea basin—Research on water management to prevent secondary salinization in rice-based cropping system in arid land  

Microsoft Academic Search

In the Lower Syr Darya region of the Aral Sea basin, secondary salinization of irrigated lands has been a crucial problem. To clarify the mechanism of secondary salinization, studies on water and salt behavior were conducted in an irrigation block where a rice-based cropping system has been practiced. Results of on-site studies are summarized as follows: (1) since the performance

Yoshinobu Kitamura; Tomohisa Yano; Toshimasa Honna; Sadahiro Yamamoto; Koji Inosako

2006-01-01

168

Extended stratigraphy, palynology and depositional environments record the initiation of the Himalayan Gyirong Basin (Neogene China)  

NASA Astrophysics Data System (ADS)

Here we report new sedimentological and paleontological data from a 603.5 m thick Neogene sequence (Woma section) in the Gyirong Basin, a basin induced by east-west extension in the Himalayas of southern Tibet. We document the conglomeratic Danzengzhukang Formation, at the base of the section, and the overlying finer grained Woma Formation that includes a Hipparion fauna. Based on stratigraphic correlations and earlier thermochronology and magnetostratigraphic results, we bracket the depositional age of this section between 10.8 Ma and 1.7 Ma. Lithology, paleo-current directions and provenance analysis, together with palynological and paleontological data, have revealed three depositional environments for the deposition of the studied section. (1) Alluvial-fan to braided river environments with ESE transport directions (Danzengzhukang Formation, <10.8 to ˜7.2 Ma) were associated with a warm and humid coniferous- and broad-leaved mixed forest. (2) Lacustrine dominated conditions (Lower Woma Formation, ˜7.2 to 3.2 Ma) with WSW transport directions were associated with locally warm and humid environments in the low-lying areas while input from a new source area suggests the presence of a high-altitude, cold and arid deciduous coniferous-leaved forests. (3) A fan delta dominated environment (Upper Woma Formation, 3.2 to >1.7 Ma) with increased denudation and WSW paleo-currents was associated with a deciduous coniferous and broad-leaved mixed forest that suggests an increase in climate variability. Our data indicate that the Gyirong Basin was under overall warm and humid conditions throughout most of its history, in agreement with high-resolution oxygen and carbon isotope data collected from the same section (this issue). We interpret our warm climate in the Gyirong Basin to reflect the prevalence of the monsoonal influence and the distal pollen sources to result from orographic effects.

Xu, Ya-Dong; Zhang, Ke-Xin; Wang, Guo-Can; Jiang, Shang-Song; Chen, Fen-Ning; Xiang, Shu-Yuan; Dupont-Nivet, Guillaume; Hoorn, Carina

2012-01-01

169

Multiphase, multicomponent parameter estimation for liquid and vapor fluxes in deep arid systems using hydrologic data and natural environmental tracers  

USGS Publications Warehouse

Multiphase, multicomponent numerical models of long-term unsaturated-zone liquid and vapor movement were created for a thick alluvial basin at the Nevada Test Site to predict present-day liquid and vapor fluxes. The numerical models are based on recently developed conceptual models of unsaturated-zone moisture movement in thick alluvium that explain present-day water potential and tracer profiles in terms of major climate and vegetation transitions that have occurred during the past 10 000 yr or more. The numerical models were calibrated using borehole hydrologic and environmental tracer data available from a low-level radioactive waste management site located in a former nuclear weapons testing area. The environmental tracer data used in the model calibration includes tracers that migrate in both the liquid and vapor phases (??D, ??18O) and tracers that migrate solely as dissolved solutes (Cl), thus enabling the estimation of some gas-phase as well as liquid-phase transport parameters. Parameter uncertainties and correlations identified during model calibration were used to generate parameter combinations for a set of Monte Carlo simulations to more fully characterize the uncertainty in liquid and vapor fluxes. The calculated background liquid and vapor fluxes decrease as the estimated time since the transition to the present-day arid climate increases. However, on the whole, the estimated fluxes display relatively little variability because correlations among parameters tend to create parameter sets for which changes in some parameters offset the effects of others in the set. Independent estimates on the timing since the climate transition established from packrat midden data were essential for constraining the model calibration results. The study demonstrates the utility of environmental tracer data in developing numerical models of liquid- and gas-phase moisture movement and the importance of considering parameter correlations when using Monte Carlo analysis to characterize the uncertainty in moisture fluxes. ?? Soil Science Society of America.

Kwicklis, E. M.; Wolfsberg, A. V.; Stauffer, P. H.; Walvoord, M. A.; Sully, M. J.

2006-01-01

170

Alluvial Bars of the Obed Wild and Scenic River, Tennessee  

USGS Publications Warehouse

In 2004, the U.S. Geological Survey (USGS) and the National Park Service (NPS) initiated a reconnaissance study of alluvial bars along the Obed Wild and Scenic River (Obed WSR), in Cumberland and Morgan Counties, Tennessee. The study was partly driven by concern that trapping of sand by upstream impoundments might threaten rare, threatened, or endangered plant habitat by reducing the supply of sediment to the alluvial bars. The objectives of the study were to: (1) develop a preliminary understanding of the distribution, morphology, composition, stability, and vegetation structure of alluvial bars along the Obed WSR, and (2) determine whether evidence of human alteration of sediment dynamics in the Obed WSR warrants further, more detailed examination. This report presents the results of the reconnaissance study of alluvial bars along the Obed River, Clear Creek, and Daddys Creek in the Obed WSR. The report is based on: (1) field-reconnaissance visits by boat to 56 alluvial bars along selected reaches of the Obed River and Clear Creek; (2) analysis of aerial photographs, topographic and geologic maps, and other geographic data to assess the distribution of alluvial bars in the Obed WSR; (3) surveys of topography, surface particle size, vegetation structure, and ground cover on three selected alluvial bars; and (4) analysis of hydrologic records.

Wolfe, W.J.; Fitch, K.C.; Ladd, D.E.

2007-01-01

171

A geochemical approach for the evaluation of water availability and salinity in closed basins: the Draa Basin, Morocco  

Microsoft Academic Search

In the sub-Saharan Draa Basin of southern Morocco, winter snowmelt from the Atlas Mountains is captured in a reservoir, stored, and discharged downstream for irrigation in six oases. The combined imported surface water and shallow groundwater exploitation for sustaining local agriculture is a common practice in many worldwide arid basins.. Like in many basins, the salinization of groundwater in the

N. Warner; Z. Lgourna; S. Boutaleb; T. Tagma; D. S. Vinson; N. Ettayfi; L. Bouchaou; A. Vengosh

2010-01-01

172

Distribution and Orientation of Alluvial Fans in Martian Craters  

NASA Technical Reports Server (NTRS)

We present the results of the complete survey of Martian alluvial fans from 0-30 S, initiated by Moore and Howard. Nineteen impact craters contain alluvial fans. They are regionally grouped into three distinct areas. We present our initial results regarding their distribution and orientation in order to understand what controls their formation. Since alluvial fans are formed by water transport of sediment, these features record wetter episodes of Martian climate. In addition, their enigmatic distribution (in regional groups and in some craters, but not similar adjacent ones) needs to be understood, to see how regional geology, topographic characteristics, and/or climate influence their formation and distribution.

Kraal, E. R.; Moore, J. M.; Howard, A. D.; Asphaug, E. I.

2005-01-01

173

Design of flood protection for transportation alignments on alluvial fans  

SciTech Connect

The method of floodplain delineation on alluvial fans developed for the national flood insurance program is modified to provide estimates of peak flood flows at transportation alignments crossing an alluvial fan. The modified methodology divides the total alignment length into drainage design segments and estimates the peak flows that drainage structures would be required to convey as a function of the length of the drainage design segment, the return period of the event, and the location of the alignment on the alluvial fan. An example of the application of the methodology is provided. 16 refs., 5 figs.

French, R.H.

1991-01-01

174

INTRODUCTION Mesopotamia is the broad, flat alluvial plain  

E-print Network

INTRODUCTION Mesopotamia is the broad, flat alluvial plain between the Tigris and Euphrates Rivers to the headwaters of the Tigris and Euphrates Rivers from ca. 4300 to 4200 B.P. Particularly important

deMenocal, Peter B.

175

The Shape of Trail Canyon Alluvial Fan, Death Valley  

NASA Technical Reports Server (NTRS)

A modified conic equation has been fit to high-resolution digital topographic data for Trail Canyon alluvial fan in Death Valley, California. Fits were accomplished for 3 individual fan units of different age.

Farr, Tom G.; Dohrenwend, John C.

1993-01-01

176

Kinematic wave model of bed profiles in alluvial channels  

E-print Network

A mathematical model, based on the kinematic wave (KW) theory, is developed for describing the evolution and movement of bed profiles in alluvial channels. The model employs a functional relation between sediment transport rate and concentration, a...

Tayfur, Gokmen; Singh, Vijay P.

2006-06-21

177

Alluvial Fans as a Record of Late Precipitation on Mars  

NASA Astrophysics Data System (ADS)

Alluvial Fans on Mars provide a record of late activity likely driven by synoptic precipitation as snowfall. Snowfall may have been concentrated into topography around craters, thereby facilitating weathering and enabling runoff during melting.

Grant, J. A.; Wilson, S. A.

2014-07-01

178

Significance of Overland Flow in Sustaining Water Resources of Arid and Semi-Arid Rivers - Water Quantity and Quality Implications  

NASA Astrophysics Data System (ADS)

Overland flow is known to be a dominant runoff generation mechanism in arid and semiarid river systems. Despite its prevalence, little is known about the impact of overland flow on the quantity and quality of water in arid and semi-arid rivers and riparian systems. Several studies along the San Pedro and Rio Grande Rivers in the Southwest United States have documented the importance of ephemeral overland flows to the quantity and quality of river water in the stream and near stream zones. First, studies on both rivers have documented the importance of flood flows in providing a significant source of water to near stream aquifers. On the San Pedro River studies have shown that ~50% of baseflow water originates from summer Monsoon floods with a stronger influence on losing versus gaining river reaches. In the Rio Grande, stable isotope data indicate that nearly 100% of the increase in discharge during a Monsoon flood event can be attributed to ephemeral overland flow with approximately 40% of this flood pulse in the Rio Grande lost to the shallow alluvial aquifer. Second, nutrient studies on both rivers demonstrate that reconnecting the river with its uplands during flood events causes a dramatic increase in nutrient concentrations and fundamentally alters near and in-stream biogeochemical conditions and processes by providing a large pulse of allochthonous nutrients and organic matter. Despite the large nutrient influx with flood events the sustained impact on nutrient composition is limited; with upwelling zones, possibly reworking particulate organic matter, having more influence than water source on in-stream nutrient concentrations. Furthermore the influence of flood events attenuates significantly over a period of months with the influence of flood events diminishing from 40% of river flow to 20% in a period of just 6 months.

Meixner, T.; Hogan, J. F.; Brooks, P. D.; Oelsner, G. P.; Soto-López, C. D.; Baillie, M. N.; Simpson, S. C.

2007-12-01

179

Inference of lithologic distributions in an alluvial aquifer using airborne transient electromagnetic surveys  

USGS Publications Warehouse

An airborne transient electromagnetic (TEM) survey was completed in the Upper San Pedro Basin in southeastern Arizona to map resistivity distributions within the alluvial aquifer. This investigation evaluated the utility of 1D vertical resistivity models of the TEM data to infer lithologic distributions in an alluvial aquifer. Comparisons of the resistivity values and layers in the 1D resistivity models of airborne TEM data to 1D resistivity models of ground TEM data, borehole resistivity logs, and lithologic descriptions in drill logs indicated that the airborne TEM identified thick conductive fine-grained sediments that result in semiconfined groundwater conditions. One-dimensional models of ground-based TEM surveys and subsurface lithology at three sites were used to determine starting models and constraints to invert airborne TEM data using a constrained Marquardt-styleunderparameterized method. A maximum structural resolution of six layers underlain by a half-space was determined from the resistivity structure of the 1D models of the ground TEM data. The 1D resistivity models of the airborne TEM data compared well with the control data to depths of approximately 100 m in areas of thick conductive silt and clay and to depths of 200 m in areas of resistive sand and gravel. Comparison of a 3D interpolation of the 1D resistivity models to drill logs indicated resistive (mean of 65 ohm-m ) coarse-grained sediments along basin margins and conductive (mean of 8 ohm-m ) fine-grained sediments at the basin center. Extents of hydrologically significant thick silt and clay were well mapped by the 1D resistivity models of airborne TEM data. Areas of uncertain lithology remain below conductive fine-grained sediments where the 1D resistivity structure is not resolved: in areas where multiple lithologies have similar resistivity values and in areas of high salinity.

Dickinson, Jesse E.; Pool, D. R.; Groom, R. W.; Davis, L. J.

2010-01-01

180

Geomorphologic flood-hazard assessment of alluvial fans and piedmonts  

USGS Publications Warehouse

Geomorphologic studies are an excellent means of flood-hazard assessment on alluvial fans and piedmonts in the southwestern United States. Inactive, flood-free, alluvial fans display well developed soils, desert pavement, rock varnish, and tributary drainage networks. These areas are easily distinguished from flood-prone active alluvial fans on aerial photographs and in the field. The distribution of flood-prone areas associated with alluvial fans is strongly controlled by fanhead trenches dissecting the surface. Where fanhead trenches are permanent features cut in response to long-term conditions such as tectonic quiescence, flood-prone surfaces are situated down-slope from the mountain front and their positions are stable for thousands of years. Since the length and permanency of fanhead trenches can vary greatly between adjacent drainages, it is not appropriate to use regional generalizations to evaluate the distribution and stability of flood-hazard zones. Site-specific geomorphologic studies must be carried out if piedmont areas with a high risk of flooding are to be correctly identified and losses due to alluvial-fan flooding minimized. To meet the growing demand for trained professionals to complete geomorphologic maps of desert piedmonts, undergraduate and graduate geomorphology courses should adopt an instructional unit on alluvial-fan flood hazards that includes: 1) a review of geomorphologic characteristics that vary with surface age; 2) a basic mapping exercise; and 3) a discussion of the causes of fanhead trenching.

Field, J.J.; Pearthree, P.A.

1997-01-01

181

The "Alluvial Mesovoid Shallow Substratum", a New Subterranean Habitat  

PubMed Central

In this paper we describe a new type of subterranean habitat associated with dry watercourses in the Eastern Iberian Peninsula, the “Alluvial Mesovoid Shallow Substratum” (alluvial MSS). Historical observations and data from field sampling specially designed to study MSS fauna in the streambeds of temporary watercourses support the description of this new habitat. To conduct the sampling, 16 subterranean sampling devices were placed in a region of Eastern Spain. The traps were operated for 12 months and temperature and relative humidity data were recorded to characterise the habitat. A large number of species was captured, many of which belonged to the arthropod group, with marked hygrophilous, geophilic, lucifugous and mesothermal habits. In addition, there was also a substantial number of species showing markedly ripicolous traits. The results confirm that the network of spaces which forms in alluvial deposits of temporary watercourses merits the category of habitat, and here we propose the name of “alluvial MSS”. The “alluvial MSS” may be covered or not by a layer of soil, is extremely damp, provides a buffer against above ground temperatures and is aphotic. In addition, compared to other types of MSS, it is a very unstable habitat. It is possible that the “alluvial MSS” may be found in other areas of the world with strongly seasonal climatic regimes, and could play an important role as a biogeographic corridor and as a refuge from climatic changes. PMID:24124544

Ortuno, Vicente M.; Gilgado, Jose D.; Jimenez-Valverde, Alberto; Sendra, Alberto; Perez-Suarez, Gonzalo; Herrero-Borgonon, Juan J.

2013-01-01

182

Quaternary climate change and hillslope processes: What can we learn from alluvial fans?  

NASA Astrophysics Data System (ADS)

Examining the timing of sediment deposition on alluvial fans may clarify relationships among Quaternary changes in climate, sediment production, and sediment removal from uplifted mountain blocks. Deposition on fans indicates that (1) ample sediment is available for transport within contributing basins and (2) that stream power is adequate to move that sediment to the fan environment. Dating alluvial fan deposition clarifies relationships among climatically controlled factors (e.g. precipitation, vegetation, temperature), and hydrologic and geomorphic responses (e.g. weathering rates, frost action, glaciation, stream power) that influence landscape evolution. Numerous 2-5 km radius, low gradient alluvial fans head along the western side of the Lost River Range (LRR) in east-central Idaho. Timing of deposition on these fans is based on optically stimulated luminescence dating (OSL). In addition we described general deposit characteristics and mapped different aged fan surfaces to explore how fan deposition has changed over time. OSL results indicate that evacuation of sediment from contributing basins and deposition on fans was enhanced ~10-14 ka and ~40-50 ka. The younger episode is more robust in this record, with deposition recorded on all five studied fans despite differences in Quaternary glacial extent in contributing basins that varied from ~0-80%. Glacial chronologies from the nearby Sawtooth Range (Thackray, 2008) and Yellowstone-Teton region (Licciardi and Pierce, 2008; Gosse et al, 1995) suggest that this time period may have coincided with and followed the last glacial maxima in the northern Rocky Mountains. Deposition during the ~40-50 ka episode is recorded on the two largest studied fans, both with <10% glaciation in basin areas, as well as a ~40 m terrace of the East Fork Big Lost River that drains the Pioneer Range west of the LRR. A ~60-65 ka moraine in the northern LRR dated by U-series on pedogenic carbonate, an extensive glacio-fluvial terrace in the Wind River Basin (~200 km east of the LRR) dated to >55 ± 8.6 ka (Sharp et al, 2003), and substantial loess accumulation near the Teton Range at ~46-54 ka (Pierce et al, personal comm.) suggest that this episode of fan deposition was late- to post-glacial with respect to the MIS 4 glaciation and associated climatic conditions. Deposition on alluvial fans generally results from (1) increases in the sediment supply and/or (2) changes in stream power that alter the relative balance between sediment supply and stream power. In this region, sediment supply could increase following glacial conditions if reduced effective moisture decreases hillslope vegetation cover, freeing accumulated regolith for transport to fans, or greater temperature fluctuations increase the effectiveness of frost weathering. Stream power following a glacial maxima may have decreased in response to effectively drier climate, but may still have been adequate to transport sediment to fans. It’s also possible that stream power increased following glacial maxima with greater frequency of stochastic events such as rain on snow.

Kenworthy, M.; Pierce, J. L.; Rittenour, T. M.; Sharp, W. D.; Pierce, K. L.

2009-12-01

183

Symbiotic nitrogen fixation by Trifolium arvense in semi?arid short tussock grasslands  

Microsoft Academic Search

We have measured symbiotic N fixation from the widespread annual Trifolium arvense (haresfoot clover) in two studies in the semi?arid zone of the Mackenzie Basin using a N dilution technique over two growing seasons. Apart from one low value of 69%, the percentage of plant nitrogen derived from the atmosphere (%Ndfa) was consistently high in one study at Tomahawk Gully

C. C. Boswell; W. L. Lowther; A. J. Rutherford

2007-01-01

184

Aerodynamic roughness parameters for semi-arid natural shrub communities of Wyoming, USA  

Microsoft Academic Search

Estimates of aerodynamic roughness length (z0) were calculated at nine sites for natural sagebrush (Artemisia tridentata spp.), saltbush (Atriplex nuttallii) and greasewood (Sarcobatus vermiculatus) plant communities in two semi-arid basins in Wyoming, USA. Estimates were based on wind and temperature profiles measured above the plant canopies during summer (August) of 1994 and fall (September and October) of 1995. Values of

Kenneth L. Driese; William A. Reiners

1997-01-01

185

A classification of Meso-Cenozoic continental basins and their oil-gas potentials in China  

SciTech Connect

Most of the oilfields in China are located in Mesozoic-Cenozoic continental basins. Characteristics of continental sediments are controlled by such factors as paleoclimatic zones, distance from oceans, paleogeomorphic features, and tectonic settings. Based on paleoclimatic zonation, the continental basins in China can be divided into humid, arid, and humid-arid transitional types. Furthermore, based on the distances from oceans, they can be classified into inland and onshore types, and based on regional geomorphic features, they can be classified into faulted and depressional types. According to three factors, the Mesozoic-Cenozoic continental petroliferous basins in China can be grouped under ten types as follows: (1) onshore humid faulted type such as Zhujiangkou (Pearl River Mouth; E); (2) onshore humid depressional type such as Songliao (K); (3) inland humid faulted type such as Baise (E); (4) inland humid depressional type such as Ordos (T); (5) onshore arid-humid faulted type such as Bohai Bay (E); (6) inland arid-humid faulted type such as Jiuxi (K); (7) inland arid-humid depressional type such as Junggar (E); (8) onshore arid depressional type such as Tarim (E); (9) inland arid faulted type such as Jianghan (E); and (10) inland arid depressional type such as Tsaidam (E-N). Sedimentary systems in different basins have different depositional characteristics and petroliferous potentials. Onshore basins in humid zone and arid-humid transitional zone have best petroleum prospects, and inland basins in humid and arid-humid transitional zones are second while the basins in arid zone are third.

Wu Changlin (Louisiana State Univ., Baton Rouge (United States)); Xue Shuhao (Research Inst. of Petroleum Exploration, Beijing (China))

1991-03-01

186

Effects of the Biofuels Initiative on Water Quality and Quantity in the Mississippi Alluvial Plain  

NASA Astrophysics Data System (ADS)

In the search for renewable fuel alternatives, biofuels have gained strong political momentum. In the last decade, extensive mandates, policies, and subsidies have been adopted to foster the development of a biofuels industry in the United States. The manifestation of the Biofuels Initiative in the Mississippi Delta was a 47-percent decrease in cotton acreage with a concurrent 288 percent increase in corn acreage in 2007. Because corn uses 80 percent more water for irrigation than cotton, and more nitrogen fertilizer is recommended for corn cultivation, this crop type change has implications for water quantity and quality in the Delta. Increased water use for corn is accelerating water-level declines in the Mississippi River Valley alluvial aquifer at a time when conservation is being encouraged due to concerns about sustainability. A mathematical model calibrated to existing conditions in the Delta shows that increased fertilizer applications on corn will increase the extent of nitrate movement into the alluvial aquifer. Estimates based on surface-water modeling results indicate that higher application rates of nitrogen from increased corn production increases the amount of nitrogen exported from the Yazoo River basin to the Gulf of Mexico by about 7 percent; increasing the Delta’s contribution to hypoxic conditions in the Gulf of Mexico.

Welch, H. L.; Green, C. T.; Coupe, R. H.

2010-12-01

187

Understanding Hydrologic Processes in Semi-Arid Cold Climates  

NASA Astrophysics Data System (ADS)

Water shortages destabilize economies and ecosystems. These shortages are caused by complex interactions between climate variability, ecosystem processes, and increased demand from human activities. In the semi-arid region of the northwestern U.S., water availability during drought periods has already reached crisis levels and the problems are expected to intensify as the effects of global climate change and population growth continue to alter the supply and demand patterns. Many of the problems are critical to this region because hydropower, agriculture, navigation, fish and wildlife survival, water supply, tourism, environmental protection, and water-based recreation are vital to state economies and our way of life. In order to assess the spatial and temporal nature of hydrologic responses, consistent and comprehensive long-term data sets are needed. In response to these needs, we would like to propose the Spokane River drainage basin as a long-term hydrologic observatory. The Spokane River basin is located in eastern Washington and northern Idaho and is a tributary of the Columbia River. The watershed consists of several major surface water tributaries as well as natural and man-made lakes and reservoirs. With headwaters beginning in the Rocky Mountains, the drainage area is approximately 6,640 mi2. In addition to providing an excellent study area for examining many conventional water resource problems, the Spokane River watershed also presents a unique opportunity for investigating many of the hydrologic processes found in semi-arid cold climates. Snowfall in the watershed varies spatially between 35 inches near the mouth of the basin to over 112 inches at the headwaters. These varied hydrologic uses provide a unique opportunity to address many common challenges faced by water resource professionals. This broad array of issues encompasses science, engineering, agriculture, social sciences, economics, fisheries, and a host of other disciplines. In addition, because precipitation patterns in this semi-arid region tend to be temporally distributed, storage and global climate change issues are significant.

Barber, M. E.; Beutel, M.; Lamb, B.; Watts, R.

2004-12-01

188

Digital-model simulation of the Toppenish alluvial aquifer, Yakima Indian Reservation, Washington  

USGS Publications Warehouse

Increasing demands for irrigating additional lands and proposals to divert water from the Yakima River by water users downstream from the Yakima Indian Reservation have made an accounting of water availability important for present-day water management in the Toppenish Creek basin. A digital model was constructed and calibrated for the Toppenish alluvial aquifer to help fulfill this need. The average difference between observed and model-calculated aquifer heads was about 4 feet. Results of model analysis show that the net gain from the Yakima River to the aquifer is 90 cubic feet per second, and the net loss from the aquifer to Toppenish Creek is 137 cubic feet per second. Water-level declines of about 5 feet were calculated for an area near Toppenish in response to a hypothetical tenfold increase in 1974 pumping rates. (USGS)

Bolke, E.L.; Skrivan, James A.

1981-01-01

189

ARID1B is a specific vulnerability in ARID1A-mutant cancers  

PubMed Central

Summary Recent studies have revealed that ARID1A is frequently mutated across a wide variety of human cancers and also has bona fide tumor suppressor properties. Consequently, identification of vulnerabilities conferred by ARID1A mutation would have major relevance for human cancer. Here, using a broad screening approach, we identify ARID1B, a related but mutually exclusive homolog of ARID1A in the SWI/SNF chromatin remodeling complex, as the number one gene preferentially required for the survival of ARID1A-mutant cancer cell lines. We show that loss of ARID1B in ARID1A-deficient backgrounds destabilizes SWI/SNF and impairs proliferation. Intriguingly, we also find that ARID1A and ARID1B are frequently co-mutated in cancer, but that ARID1A-deficient cancers retain at least one ARID1B allele. These results suggest that loss of ARID1A and ARID1B alleles cooperatively promotes cancer formation but also results in a unique functional dependence. The results further identify ARID1B as a potential therapeutic target for ARID1A-mutant cancers. PMID:24562383

Helming, Katherine C.; Wang, Xiaofeng; Wilson, Boris G.; Vazquez, Francisca; Haswell, Jeffrey R.; Manchester, Haley E.; Kim, Youngha; Kryukov, Gregory V.; Ghandi, Mahmoud; Aguirre, Andrew J.; Jagani, Zainab; Wang, Zhong; Garraway, Levi A.; Hahn, William C.; Roberts, Charles W. M.

2014-01-01

190

Calibration of the ARID robot  

NASA Technical Reports Server (NTRS)

The author has formulated a new, general model for specifying the kinematic properties of serial manipulators. The new model kinematic parameters do not suffer discontinuities when nominally parallel adjacent axes deviate from exact parallelism. From this new theory the author develops a first-order, lumped-parameter, calibration-model for the ARID manipulator. Next, the author develops a calibration methodology for the ARID based on visual and acoustic sensing. A sensor platform, consisting of a camera and four sonars attached to the ARID end frame, performs calibration measurements. A calibration measurement consists of processing one visual frame of an accurately placed calibration image and recording four acoustic range measurements. A minimum of two measurement protocols determine the kinematics calibration-model of the ARID for a particular region: assuming the joint displacements are accurately measured, the calibration surface is planar, and the kinematic parameters do not vary rapidly in the region. No theoretical or practical limitations appear to contra-indicate the feasibility of the calibration method developed here.

Doty, Keith L

1992-01-01

191

Caribbean basin framework, 3: Southern Central America and Colombian basin  

SciTech Connect

The authors recognize three basin-forming periods in southern Central America (Panama, Costa Rica, southern Nicaragua) that they attempt to correlate with events in the Colombian basin (Bowland, 1984): (1) Early-Late Cretaceous island arc formation and growth of the Central American island arc and Late Cretaceous formation of the Colombian basin oceanic plateau. During latest Cretaceous time, pelagic carbonate sediments blanketed the Central American island arc in Panama and Costa Rica and elevated blocks on the Colombian basin oceanic plateau; (2) middle Eocene-middle Miocene island arc uplift and erosion. During this interval, influx of distal terrigenous turbidites in most areas of Panama, Costa Rica, and the Colombian basin marks the uplift and erosion of the Central American island arc. In the Colombian basin, turbidites fill in basement relief and accumulate to thicknesses up to 2 km in the deepest part of the basin. In Costa Rica, sedimentation was concentrated in fore-arc (Terraba) and back-arc (El Limon) basins; (3) late Miocene-Recent accelerated uplift and erosion of segments of the Central American arc. Influx of proximal terrigenous turbidites and alluvial fans in most areas of Panama, Costa Rica, and the Colombian basin marks collision of the Panama arc with the South American continent (late Miocene early Pliocene) and collision of the Cocos Ridge with the Costa Rican arc (late Pleistocene). The Cocos Ridge collision inverted the Terraba and El Limon basins. The Panama arc collision produced northeast-striking left-lateral strike-slip faults and fault-related basins throughout Panama as Panama moved northwest over the Colombian basin.

Kolarsky, R.A.; Mann, P. (Univ. of Texas, Austin (United States))

1991-03-01

192

Hydrological Responses to Climate Change and to LUCC in Asian Arid Zone  

NASA Astrophysics Data System (ADS)

The arid Asian zone is one of the most sensitive areas to the global climate change. For instance, the temperature has been rising at a rate of 0.39K/10yrs in the arid northwestern China during the past an half of century, being 2.78 times of the global average. In the arid Asian zone, water resource is a key factor restricting the socio-economic development and threatening the ecological security. Under the global warming conditions, water resource systems of the arid Asian zone are most likely becoming increasingly vulnerable, especially under the projected increasing population and expanding economy in arid Asian zone. Hydrological data from glacier-supplied rivers in the Tian Shan Mountains for example show that the runoff has been increasing primarily as a result of rising temperature that caused increases in ice melting. But, the decreasing trend of surface runoff in low-elevation basins is undeniable and the decreasing trend is attributable to the increasingly intensified human activities. Specifically, increasingly intensified water consumption for irrigation and the associated massive constructions of water conservancy projects were responsible for the decreasing trend of runoff. And, the decreasing trend has been severely jeopardizing the ecological security in the lower reaches of the arid river basins. In arid northwestern China, about 85% of the water resources are formed in high elevations and the glacier-melting contribution to runoff has been doubled since 1980's. Approaching to the turning point of glacier-melting supplies to runoff will pose a great threat to socio-economic sustainability and to ecological security. The turning point refers to the transition from increasing runoff to decreasing runoff within glacier-melting supplied watersheds under warming climate.

Feng, Zhaodong

2013-04-01

193

Hydrological Response of Semi-arid Degraded Catchments in Tigray, Northern Ethiopia  

NASA Astrophysics Data System (ADS)

To address water scarcity in the arid and semi-arid part of developing countries, accurate estimation of surface runoff is an essential task. In semi-arid catchments runoff data are scarce and therefore runoff estimation using hydrological models becomes an alternative. This research was initiated in order to characterize runoff response of semi-arid catchments in Tigray, North Ethiopia to evaluate SCS-CN for various catchments. Ten sub-catchments were selected in different river basins and rainfall and runoff were measured with automatic hydro-monitoring equipments for 2-3 years. The Curve Number was estimated for each Hydrological Response Unit (HRU) in the sub-catchments and runoff was modeled using the SCS-CN method at ? = 0.05 and ? = 0.20. The result showed a significant difference between the two abstraction ratios (P =0.05, df = 1, n= 132) and reasonable good result was obtained for predicted runoff at ? = 0.05 (NSE = -0.69; PBIAS = 18.1%). When using the CN values from literature runoff was overestimated compared to the measured value (e= -11.53). This research showed the importance of using measured runoff data to characterize semi-arid catchments and accurately estimate the scarce water resource. Key words: Hydrological response, rainfall-runoff, degraded environments, semi-arid, Ethiopia, Tigray

Teka, Daniel; Van Wesemael, Bas; Vanacker, Veerle; Hallet, Vincent

2013-04-01

194

Aridity threshold in controlling ecosystem nitrogen cycling in arid and semi-arid grasslands  

NASA Astrophysics Data System (ADS)

Higher aridity and more extreme rainfall events in drylands are predicted due to climate change. Yet, it is unclear how changing precipitation regimes may affect nitrogen (N) cycling, especially in areas with extremely high aridity. Here we investigate soil N isotopic values (?15N) along a 3,200?km aridity gradient and reveal a hump-shaped relationship between soil ?15N and aridity index (AI) with a threshold at AI=0.32. Variations of foliar ?15N, the abundance of nitrification and denitrification genes, and metabolic quotient along the gradient provide further evidence for the existence of this threshold. Data support the hypothesis that the increase of gaseous N loss is higher than the increase of net plant N accumulation with increasing AI below AI=0.32, while the opposite is favoured above this threshold. Our results highlight the importance of N-cycling microbes in extremely dry areas and suggest different controlling factors of N-cycling on either side of the threshold.

Wang, Chao; Wang, Xiaobo; Liu, Dongwei; Wu, Honghui; Lü, Xiaotao; Fang, Yunting; Cheng, Weixin; Luo, Wentao; Jiang, Ping; Shi, Jason; Yin, Huaqun; Zhou, Jizhong; Han, Xingguo; Bai, Edith

2014-09-01

195

Sediment mixing and basin-wide cosmogenic nuclide analysis in rapidly-eroding mountainous environments  

E-print Network

nuclide concentrations in alluvial sediments have been widely used to estimate basin-wide denudation rates Mountains, California 1. Introduction Measuring basin-wide denudation rates using the concentration of in al., 2000; Granger et al., 2001; Safran et al., 2005). Furthermore, recording an integrated

196

Field surveys in the Willapa River basin, Washington State, indicate that the drainage  

E-print Network

ABSTRACT Field surveys in the Willapa River basin, Washington State, indicate that the drainage, but that the pro- portion of forced alluvial channels varies from 0% to 84%. Using the drainage area be considered at two different scales. At the scale of entire drainage basins, bedrock channels are mountain

Montgomery, David R.

197

A summary of methods for the collection and analysis of basic hydrologic data for arid regions  

USGS Publications Warehouse

This report summarizes and discusses current methods of collecting and analyzing the data required for a study of the basic hydrology of arid regions. The fundamental principles behind these methods are no different than those that apply to studies of humid regions, but in arid regions the infrequent occurrence of precipitation, the great variability of the many hydrologic elements, and the inaccessibility of most basins usually make it economically infeasible to use conventional levels of instrumentation. Because of these economic considerations hydrologic studies in arid regions have been commonly of the reconnaissance type; the more costly detailed studies are generally restricted to experimental basins and to those basins that now have major economic significance. A thorough search of the literature and personal communication with workers in the field of arid-land hydrology provided the basis for this summary of methods used in both reconnaissance and detailed hydrologic studies. The conclusions reached from a consideration of previously reported methods are interspersed in this report where appropriate.

Rantz, S.E.; Eakin, T.E.

1971-01-01

198

75 FR 62137 - Notice of Public Meeting; Proposed Alluvial Valley Floor Coal Exchange Public Interest Factors...  

Federal Register 2010, 2011, 2012, 2013

...Public Meeting; Proposed Alluvial Valley Floor Coal Exchange Public Interest Factors; Montana...to consider a proposal to exchange Federal coal deposits for Alluvial Valley Floor (AVF) fee coal pursuant to the Federal Land Policy and...

2010-10-07

199

SEDIMENTOLOGY AND GEOMORPHOLOGY OF QUATERNARY ALLUVIAL FANS WITH IMPLICATIONS TO GROWTH STRATA, LOST RIVER RANGE,  

E-print Network

The Wyoming Geological Association's J.D. Love Fellowship The Letters and Science Enhancement Award Hayley......................................................................................14 5. UPPER CEDAR CREEK ALLUVIAL FAN.............................................. 19 Surface 6. JONES CREEK ALLUVIAL FAN......................................................... 67 Surface

Lawrence, Rick L.

200

Challenges in Arid-Land Meteorology  

NASA Astrophysics Data System (ADS)

A fundamental challenge in desert meteorology involves quantifying the various components of the water cycle for the coupled land-atmospheric system. Important issues include defining the fraction of precipitated water that actually reaches the ground, and, of the water that does reach the surface, how much is partitioned among evaporation, runoff to reservoirs, retention near the surface in substrates for use by vegetation, and percolation to the water table. Because monsoon rainfall is often a significant source of water in the hydrologic cycle in arid lands, understanding its inter-annual variability and improving its predictability are challenges. In addition, there are questions about how continued anthropogenic modification of the landscape will influence local weather processes and climate, in terms of changes due to agricultural conversion (including reversion away from agriculture as water tables drop), the urban conversion of prairie grassland and desert vegetation to asphalt and trees, and the trans-basin diversion of water. Predicting the elevation from the surface and the transport of natural and anthropogenic aerosols is also important in terms of their affect on the local and global radiation budget and climate, downwind effects on human health, and local and remote cloud processes. Lastly, large substrate and vegetation heterogeneities, frequently very complex orography, and extreme diurnal cycles present challenges in understanding and modeling land-atmosphere interaction and boundary-layer processes.

Warner, T. T.

2005-12-01

201

A GIS-based Estimate of Net Erosion Rate for Semi-arid Watersheds in New Mexico Richardson, C.P.1  

E-print Network

A GIS-based Estimate of Net Erosion Rate for Semi-arid Watersheds in New Mexico Richardson, C.P.1 subsequent management for beneficial use. GIS-based modeling and evaluation is another tool to evaluate-basin of the Rio Puerco basin to the Rio Grande. Objective The objective of this work is to utilize a GIS platform

Cal, Mark P.

202

Myxobacters from Arid Mexican Soil  

PubMed Central

Myxobacters were found to be common inhabitants of the arid soils from the Monterrey, Nuevo Leon, Mexico, area. Thirteen species of the genera Myxococcus, Archangium, Cystobacter, Stigmatella, Polyangium, and Chondromyces were isolated on a mineral salts agar supplemented with bakers' yeast and filter paper. Greater species diversity per soil sample was found in the region receiving 400 to 800 mm of annual rainfall as compared with soils from an area having only 200 to 400 mm of rainfall. PMID:16345178

Brockman, Ellis R.

1976-01-01

203

Ephemeral rivers and their development: testing an approach to basin management committees on the Kuiseb River, Namibia  

NASA Astrophysics Data System (ADS)

Ephemeral rivers are located in the world’s drylands where aridity and climate variability are key environmental determinants. The Kuiseb River is one of two diversely developed ephemeral rivers in western-central Namibia. From up to down stream, freehold-tenure farmers, a national park, communal farmers and the port and municipality of Walvis Bay all derive water from this source. Upstream farmers impound surface water during brief rainfall periods while remaining stakeholders’ abstract water from the alluvial aquifer. The draft Water Resources Management Act for Namibia devotes one chapter to basin management committees as mechanisms to ensure more equitable, efficient and effective sharing of water resources and their benefits. Two pilot committees are being established in Namibia, one of which is in the Kuiseb basin. The Environmental Learning and Action in the Kuiseb project, implemented by the Desert Research Foundation of Namibia in close consultation with Namibia’s Water Resources Management Review with funding from the European Union, has brought all stakeholders together. The Department of Water Affairs, NamWater and the Gobabeb Training and Research Centre are contributing information to enhance understanding of the river’s functions and services provided. All stakeholders are sharing information concerning their needs, expectations and contributions toward integrated management of the Kuiseb. After negotiation for one-and-a-half years, a formal committee is established and mechanisms for its functioning and sustainability are being identified. The main benefit to date is the dialogue, good will and interest that have been established amongst the stakeholders. If the momentum is maintained, this will lead to a new, more integrated approach to resource management in the entire basin.

Botes, A.; Henderson, J.; Nakale, T.; Nantanga, K.; Schachtschneider, K.; Seely, M.

204

Alluvial aquifer contamination: Exchangeable heavy metals and factors affecting their spatial distribution  

Microsoft Academic Search

The distributions of ammonium acetate — extracted (‘exchangeable’) Co, Ni, Cu, Zn, Cd and Pb were determined in alluvial sediments of the Sava River at Novi Beograd (Belgrade aquifer, Yugoslavia). Samples were taken from the river bottom and from three drill-holes in the alluvial formation (in increasing distance from the river-bed). The alluvial samples included the quaternary formation — humified

Predrag Poli?; Petar Pfendt

1994-01-01

205

Rapid post-Pliocene crustal shortening in northern Tibet: Evidence from the Kumkuli Basin, Xinjiang Province, China  

NASA Astrophysics Data System (ADS)

The Altyn Tagh and Kunlun strike-slip faults dominate the modern deformation of northern Tibetan Plateau. We present shortening magnitudes and rates from the deformed Kumkuli Basin (~4000 m a.s.l.), located near the intersection of these faults ~80 km south of the Altyn Tagh and ~200 km northwest of the termination of the Kunlun fault. Quaternary vertical uplift rates of ~2.5-3 mm/yr occur beneath range front faults and folding of Eocene - Pliocene sediments record a total of >26% of post-Pliocene shortening. Basin infilling initiated in Eocene time and continued through Pliocene time with deposition of conglomerates to fluvial and lacustrine sediments. Notable Miocene gypsum beds indicate an arid environment and likely act as a zone of structural weakness in ongoing deformation. Paleocurrent directions indicate northward paleo-flow that sourced material from the Hoh Xil Basin located 150 km to the south of the Kumkuli Basin depocenter. Subsequent basin closure in Miocene time resulted from the uplift of the Quimen Tagh range to the north. Post-Pliocene deformation of basin sediments form a ~ 1 km high mountain range where a net of >12 km shortening is estimated from balanced cross sections. Folded Quaternary alluvial fan surfaces indicate that crustal shortening is ongoing. We combine new 36Cl cosmogenic radionuclide dating of depth profiles at the peaks of two folds with geomorphic reconstructions to estimate ~550 m of vertical fault motion since ~200 ka on subsurface thrust faults. We relate upper crustal shortening of the Kumkuli Bsain with left-lateral slip along the nearby Altyn Tagh fault and continued upward growth of the plateau in a region between major strike-slip faults and the rigid basement material of the Qaidam Basin. Although localized, Quaternary rates presented here are among the highest shortening rates documented in northern Tibet. Rapid upper crustal shortening at high elevations compounded with an addition of lower crustal material at depth may provide a mechanism by which northern Tibet reached elevations of >5000 m.

Yakovlev, P. V.; Clark, M. K.; Niemi, N. A.; Chang, H.; Yi, J.

2013-12-01

206

On Earthquake Ground Motion and Structural Response in Alluvial Valleys  

E-print Network

On Earthquake Ground Motion and Structural Response in Alluvial Valleys By Jacobo Bielak 1 , Member amplification and structural dam­ age due to local site conditions in sedimentary valleys during earthquakes the 1988 Armenia Earthquake. A more realistic two­dimensional finite element analysis is performed herein

Shewchuk, Jonathan

207

MAP OF ECOREGIONS OF THE MISSISSIPPI ALLUVIAL PLAIN  

EPA Science Inventory

The ecoregions of The Mississippi Alluvial Plain (73) have been identified, mapped, and described and provide a geographic structure for environmental resources research, assessment, monitoring, and management. This project is part of a larger effort by the U.S. EPA to create a ...

208

Bed Material Transport and the Morphology of Alluvial River  

E-print Network

Bed Material Transport and the Morphology of Alluvial River Channels Michael Church DepartmentUniversityofBritishColumbiaLibraryon12/27/06.Forpersonaluseonly. #12;Bed material: material that forms the bed and lower banks of the river and chiefly determines the morphology of the channel Wash material: material that, once entrained

Jellinek, Mark

209

Bed Material Transport and the Morphology of Alluvial River  

E-print Network

Bed Material Transport and the Morphology of Alluvial River Channels Michael Church DepartmentSimonFraserUniversityon08/10/06.Forpersonaluseonly. #12;Bed material: material that forms the bed and lower banks of the river and chiefly determines the morphology of the channel Wash material: material that, once entrained

Venditti, Jeremy G.

210

Modern alluvial fan and deltaic sedimentation in a foreland tectonic setting: the Lower Mesopotamian Plain and the Arabian Gulf  

NASA Astrophysics Data System (ADS)

The Arabo-Persian Gulf, generally considered as a classical carbonate basin, in fact also includes important terrigenous systems whose nature and geometry are related closely to the tectonic framework. The Gulf is bordered along its northeastern periphery by an active alpine system which constitutes a major source of both siliceous and calcareous detritus. There are four types of terrigenous discharge which are classified according to their structural relationships. Numerous alluvial fans terminate ephemeral consequent streams draining the flanks of anticlines forming the external parts of the Zagros Mountain belt. Alluvial-fan deltas studied in detail in southeastern Iran terminate semi-permanent streams which flow along major synclinal axis. They are composed mainly of fine carbonate detritus, part of which accumulates as spectacular marine mud banks. Two major types of delta occur. Relatively small marine deltas, associated with permanent antecedent streams which cross the Zagros fold system, are scattered along the Persian shoreline. The other is the a major deltaic complex which is associated with the Tigris-Euphrates Rivers. This system has prograded along the main axis of the Gulf, the resulting Mesopotamian Plain filling at least half of the original basin which, in early Quaternary times, extended from Hormuz to Syria.

Baltzer, Frédéric; Purser, Bruce H.

1990-05-01

211

Structure of Alluvial Valleys from 3-D Gravity Inversion: The Low Andarax Valley (Almería, Spain) Test Case  

NASA Astrophysics Data System (ADS)

This paper presents a gravimetric study (based on 382 gravimetric stations in an area about 32 km2) of a nearly flat basin: the Low Andarax valley. This alluvial basin, close to its river mouth, is located in the extreme south of the province of Almería and coincides with one of the existing depressions in the Betic Cordillera. The paper presents new methodological work to adapt a published inversion approach (GROWTH method) to the case of an alluvial valley (sedimentary stratification, with density increase downward). The adjusted 3D density model reveals several features in the topography of the discontinuity layers between the calcareous basement (2,700 kg/m3) and two sedimentary layers (2,400 and 2,250 kg/m3). We interpret several low density alignments as corresponding to SE faults striking about N140-145°E. Some detected basement elevations (such as the one, previously known by boreholes, in Viator village) are apparently connected with the fault pattern. The outcomes of this work are: (1) new gravimetric data, (2) new methodological options, and (3) the resulting structural conclusions.

Camacho, Antonio G.; Carmona, Enrique; García-Jerez, Antonio; Sánchez-Martos, Francisco; Prieto, Juan F.; Fernández, José; Luzón, Francisco

2014-08-01

212

Increased storminess during MIS3 altered the late Quaternary basin-scale weathering, erosion, and deposition in Nahal Yael, hyperarid Negev, Israel  

NASA Astrophysics Data System (ADS)

A conceptual model for geomorphic response to Pleistocene to Holocene climate change (Bull and Schick, 1979, Quat. Res. 11: 153-171) was probably based on earlier observations in the southwestern US, but first applied to the hyperarid (<30 mm yr-1) Nahal Yael watershed, southern Negev desert. This influential model includes a chain of events following a climate change from semiarid late Pleistocene to hyperarid Holocene: reduced vegetation cover, increased yield of sediments from slopes, and accelerated aggradation of terraces and export of sediment from the basin to deposit an alluvial fan. The model is now >30 years old and during this time chronologic, paleoenvironmental and hydrogeomorphic research have all advanced but the discussions are still within the framework put forward then. The model is revaluated here by using data acquired in Nahal Yael over the 30 years since the original model was proposed. Recent studies indicate late Pleistocene climate was hyperarid and the transition from semiarid to hyperarid climates did not occur. The revised chronology reveals a 35-20 ka episode (probably already beginning at ~50 ka with lower rates) of accelerated weathering and sediment production and distinct talus accretion on slopes. Coeval with accretion on slopes, sediments were also transported and aggraded in fluvial terraces and alluvial fans, without noticeable lag time or a chain of discernable events. This intensified sediment production and delivery phase is unrelated to the Pleistocene-Holocene transition. The depositional landforms were rapidly incised during 20-18 ka; since this approximately LGM incision, sediment yield is from the storage in these depositional landforms and is not produced from bedrock in significant quantities. We propose that in such hyperarid environment, the main operators are individual extreme storms, and in this case specifically an episode of frequent storms and floods is the driver of change regardless the mean climatic conditions. It created a pulse of intense weathering due to numerous cycles of wetting and drying on slopes and sediment transport to fluvial terraces and alluvial fans; its impact continues all the way to the present. We suggest that even if aspects of the original conceptual model of Bull and Schick (1979) are correct, it has been applied too frequently, too generally, across very diverse arid climates and settings, and for too long in lieu of collecting new data at a full basin scale and testing the model.

Enzel, Y.; Amit, R.; Grodek, T.; Ayalon, A.; Lekach, J.; Porat, N.; Bierman, P. R.; Blum, J. D.; Erel, Y.

2012-12-01

213

Morphostructural characterization of the Charco basin and its surrounding areas in the Chihuahua segment of north Mexican Basin and Range Province  

NASA Astrophysics Data System (ADS)

The Chihuahua Basin and Range (CBR) is the eastern branch of the northern Mexican Basin and Range Province that, from a morphostructural point of view, presently is one amongst the lesser-known zones of the southern portion of the North America Basin and Range Province. The study area covers an approximately 800 km2-wide portion of the CBR and encompasses the fault-bounded Charco basin and its surrounding areas. The bedrock of the area pertains to the large siliceous-igneous province of the Sierra Madre Occidental and consists of volcanoclastic rocks including Oligocene dacite, rhyolite, rhyolitic tuffs, and polimitic conglomerates. The region is characterized by a series of NW-SE oriented valleys delimited by tilted monoclinal blocks bounded by high angle, SW-dipping, normal faults. Abrupt changes in elevation, alternating between narrow faulted mountain chains and flat arid valleys or basins are the main morphological elements of the area. The valleys correspond to structural grabens filled with Plio-Pleistocene continental sediments. These grabens are about 10 km wide, while the extensional fault system extend over a distance of more than 15 km. The mountain ranges are in most cases continuous over distances that range from 10 to 70 km including different branches of the extensional and transfer faults. The morphogenesis is mainly erosive in character: erosional landforms (such as rocky scarps, ridges, strath-terraces, erosional pediment, reverse slopes, landslide scar zones, litho-structural flat surfaces) dominate the landscape. In contrast, Quaternary depositional landforms are mainly concentrated within the flat valleys or basins. The Quaternary deposits consist of wide alluvial fans extending to the foot of the main ridges, fluvial and debris-slope deposits. The morphostructural characterization of the area integrated different methodologies, including: i) geomorphological and structural field analyses; ii) remote sensing and geo-morphometric investigations based on aerial photos and Digital Elevation Models (a 28x28 m DEM and high-resolution LIDAR dataset in key sites), and iii) geophysical investigations (high resolution reflection seismic profiling combined with refraction seismic tomography). The main outputs of this research are as follows: i) the Charco basin master-faults and their conjugate extensional system were geometrically characterized and their main associated landforms mapped and described; ii) the morphostratigraphic correlations amongst both deformed and tectonically unaffected Quaternary deposits revealed that the Charco basin master fault has been inactive over the Holocene; iii) the main extensional fault system is associated with conjugate faults, oriented approximately SSW-NNE, that segmented the Charco basin master faults and favored the deposition of the most recent piedmont fans along the eastern margin of the basin; iv) the local morphostructures had played a dominant influence on the Quaternary evolution of both drainage network and relief landforms.

Troiani, Francesco; Menichetti, Marco

2014-05-01

214

Sediment-water interaction as a control on geochemical evolution of playa lake systems in the Australian arid interior  

Microsoft Academic Search

Saline playa lakes represent major geomorphic and hydrologic components of internal drainage basins in the arid to semiarid interior of Australia. These lakes mark the outcrop areas of regional shallow groundwater; thus, they are effective hydro-chemical sinks for elemental concentration and authigenic formation of carbonate, evaporite, and silica\\/silicate minerals.

A. V. Arakel; G. Jacobson; W. B. Lyons

1990-01-01

215

Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia  

NASA Astrophysics Data System (ADS)

The magnitude and timing of deep drainage and salt leaching through clay soils is a critical issue for dryland agriculture in semi-arid regions (<500 mm yr-1 rainfall), such as parts of Australia's Murray-Darling Basin (MDB). In this unique study, hydrogeological measurements and estimations of the historic water balance of crops grown on overlying Grey Vertosols were combined to estimate the contribution of deep drainage below crop roots to recharge and salinization of shallow groundwater. Soil sampling at two sites on the alluvial flood plain of the Lower Namoi catchment revealed significant peaks in chloride concentrations at 0.8-1.2 m depth under perennial vegetation and at 2.0-2.5 m depth under continuous cropping indicating deep drainage and salt leaching since conversion to cropping. Total salt loads of 91-229 t ha-1 NaCl equivalent were measured for perennial vegetation and cropping, with salinity to ?10 m depth that is not detected by shallow soil surveys. Groundwater salinity varied spatially from 910 to 2430 mS m-1 at 21 to 37 m depth (N = 5), whereas deeper groundwater was less saline (290 mS m-1) with use restricted to livestock and rural domestic supplies in this area. The Agricultural Production Systems Simulator (APSIM) software package predicted deep drainage of 3.3-9.5 mm yr-1 (0.7-2.1% rainfall) based on site records of grain yields, rainfall, salt leaching and soil properties. Predicted deep drainage was highly episodic, dependent on rainfall and antecedent, and over a 39 yr period was restricted mainly to the record wet winter of 1998. During the study period, groundwater levels were unresponsive to major rainfall events (70 and 190 mm total), and most piezometers at about 18 m depth remained dry. In this area, at this time, recharge negligible due to low rainfall and large potential evapotranspiration, transient hydrological conditionsafter changes in land use and a thick clay dominated vadose zone. This is in contrast to regional groundwater modelling that assumes annual recharge of 0.5% of rainfall. Importantly, it was found that leaching from episodic deep drainage could not cause discharge of saline groundwater in the area, since the water table was several meters below the incised river bed.

Timms, W. A.; Young, R. R.; Huth, N.

2011-11-01

216

Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia  

NASA Astrophysics Data System (ADS)

The magnitude and timing of deep drainage and salt leaching through clay soils is a critical issue for dryland agriculture in semi-arid regions (<500 mm yr-1 rainfall, potential evapotranspiration >2000 mm yr-1) such as parts of Australia's Murray-Darling Basin (MDB). In this rare study, hydrogeological measurements and estimations of the historic water balance of crops grown on overlying Grey Vertosols were combined to estimate the contribution of deep drainage below crop roots to recharge and salinization of shallow groundwater. Soil sampling at two sites on the alluvial flood plain of the Lower Namoi catchment revealed significant peaks in chloride concentrations at 0.8-1.2 m depth under perennial vegetation and at 2.0-2.5 m depth under continuous cropping indicating deep drainage and salt leaching since conversion to cropping. Total salt loads of 91-229 t ha-1 NaCl equivalent were measured for perennial vegetation and cropping, with salinity to ? 10 m depth that was not detected by shallow soil surveys. Groundwater salinity varied spatially from 910 to 2430 mS m-1 at 21 to 37 m depth (N = 5), whereas deeper groundwater was less saline (290 mS m-1) with use restricted to livestock and rural domestic supplies in this area. The Agricultural Production Systems Simulator (APSIM) software package predicted deep drainage of 3.3-9.5 mm yr-1 (0.7-2.1% rainfall) based on site records of grain yields, rainfall, salt leaching and soil properties. Predicted deep drainage was highly episodic, dependent on rainfall and antecedent soil water content, and over a 39 yr period was restricted mainly to the record wet winter of 1998. During the study period, groundwater levels were unresponsive to major rainfall events (70 and 190 mm total), and most piezometers at about 18 m depth remained dry. In this area, at this time, recharge appears to be negligible due to low rainfall and large potential evapotranspiration, transient hydrological conditions after changes in land use and a thick clay dominated vadose zone. This is in contrast to regional groundwater modelling that assumes annual recharge of 0.5% of rainfall. Importantly, it was found that leaching from episodic deep drainage could not cause discharge of saline groundwater in the area, since the water table was several meters below the incised river bed.

Timms, W. A.; Young, R. R.; Huth, N.

2012-04-01

217

Depth to bedrock using gravimetry in the Reno and Carson City, Nevada, basins Robert E. Abbott and John N. Louie  

E-print Network

of geothermal wells, and one wildcat oil well. Depths in Carson City are consistent with depths from existing rarely exceed 200 m. INTRODUCTION Alluvial basins can amplify the magnitude and lengthen the duration-to-bedrock data to create a 3-D simulation of seismic waves in the Santa Clara, California, basin. Efforts

218

Landform map of the Kaiparowits Coal-Basin area, Utah  

SciTech Connect

A 1:125,000 scale map of the Kaiparowits Coal-Basin area of Utah is presented. The map portrays the shape and erosional resistance of and features, and it is intended to be a modified slope-analysis map for use by planners in their identification of areas suitable for transportation routes and construction sites. Depositional landforms such as alluvial flats, stream courses, dune fields, and alluviated pediments are shown, and a stratigraphic section of the rocks in the area is provided. (JMT)

Sargent, K.A.; Hansen, D.E.

1980-01-01

219

Detectability of minerals on desert alluvial fans using reflectance spectra  

NASA Technical Reports Server (NTRS)

The visible and near-infrared reflectance spectra of soil samples collected from desert alluvial and colluvial surfaces in the Cuprite mining district, Nevada, were analyzed. These surfaces are downslope from hydrothermally altered volcanic rocks that contain spectrally characteristic minerals such as alunite and kaolinite. Coarse fractions of the soils on the alluvial fans are mineralogically variable and express the upslope lithologies; fine fractions are remarkably similar mineralogically and spectrally in all samples because of dilution of local mineral components by regionally derived windblown dust. Theoretical models for spectral mixing and for particle-size effects were used to model the observed spectral variations. Diagnostic mineral absorption bands in the spectra of fan materials were enhanced by computationally removing the spectrum of the homogeneous fine-soil component. Results show that spectral mixing models are useful for analyzing data with high spectral resolution obtained by field and aircraft spectrometers.

Shipman, Hugh; Adams, John B.

1987-01-01

220

RIVERBANK FILTRATION EFFECTIVENESS IN AN ARID ENVIRONMENT  

EPA Science Inventory

This experiment is a field test of bank filtration at a site where water level and salinity vary on an annual basis, as they do in many arid and semi-arid streams. No other studies of bank filtration have been performed in this kind of setting. Along the border with Mexico, shall...

221

Kinematic analysis of the ARID manipulator  

NASA Technical Reports Server (NTRS)

The kinematic structure of the ARID manipulator lends itself to simple forward and inverse kinematics analysis. The purpose of this paper is to fully document and verify an existing analysis. The symbolic software package MATHEMATICA was used to produce and verify the equations presented here. In the analysis to follow, the standard Devenit-Hartenberg kinematic parameters of the ARID were employed.

Doty, Keith L

1992-01-01

222

Contrasting soil physical properties after zero and traditional tillage of an alluvial soil in the semi-arid subtropics  

Microsoft Academic Search

Zero till is commonly advocated as a preferred cropping system to conventional, multicultivation practices. Zero till is particularly attractive on clay soils, to minimise compaction and induce natural structure formation through shrink–swell cycles. Increases in soil water storage and increased numbers of (beneficial) soil fauna with zero till have been reported, relative to traditional tillage. This work identifies reasons for

D. McGarry; B. J. Bridge; B. J. Radford

2000-01-01

223

A Numerical Model of Retreating Alluvial Fan Coasts  

Microsoft Academic Search

A numerical model has been developed that simulates the wave-driven retreat of partially-consolidated alluvial- fan shores over millennium time-scales. It has been developed to reproduce the shore profiles and coastal erosion rates observed along the Pleistocene glacial-outwash fan built by the Waitaki River on the east coast of New Zealand's South Island. This cliffed shore is currently fronted by a

M. Hicks; M. Dickson; G. Coco

2006-01-01

224

Contaminated Alluvial Ground Water in the Butte Summit Valley  

Microsoft Academic Search

.  Ground water in alluvial sediments of upper Silver Bow Creek is chronically contaminated with heavy metals, including Cd,\\u000a Cu, Fe, Mn, and Zn. Most of this contamination stems from slag, mill tailings, and waste rock from the Butte mining district\\u000a that had been deposited along the ancestral Silver Bow Creek floodplain. Much of this mine waste is now buried by

Christopher H. Gammons; James P. Madison

2006-01-01

225

A model of channel response in disturbed alluvial channels  

USGS Publications Warehouse

Dredging and straightening of alluvial channels between 1959 and 1978 in West Tennessee caused a series of morphologic changes along modified reaches and tributary streams. Degradation occurred for 10 to 15 years at sites upstream of the area of maximum disturbance and lowered bed-levels by as much as 6.1 m. Following degradation, reaches upstream of the area of maximum disturbance experienced a secondary aggradation phase in response to excessive incision and gradient reduction. -from Author

Simon, A.

1989-01-01

226

Bahia Adair and vicinity, Sonora: modern siliciclastic-dominated arid macrotidal coastline  

SciTech Connect

The northwestern Sonoran coastline, in the vicinity of Bahia Adair, combines several important geologic features. The arid landward environments are dominated by the dunes of the Gran Desierto and the surrounding alluvial fans and ephemeral streams. The Colorado River, whose delta lies to the northwest, has been an important source of sediment until very recently. The high tidal energy of the region has profoundly influenced the distribution and geometries of coastal and shallow-marine sand bodies, and the active tectonic setting has also played a role. The Cerro Prieto splay of the San Andreas fault system has been responsible for local uplift and downwarp and resulting transgression and regression. The intertidal and supratidal zones are dominated by sand and constitute a sand-body type that has been seldom considered by petroleum explorationists or other students of ancient sand bodies, and the associated evaporites are rather different from those described from the superficially analogous Persian Gulf sabkhas.

Lock, B.E.; Sinitiere, S.M.; Williams, L.J.

1989-03-01

227

New constraints on the uplift history of the western Andes, north Chile, using cosmogenic He-3 in alluvial boulders  

NASA Astrophysics Data System (ADS)

To constrain mechanisms responsible for mountain belt growth independent methods for determining accurately the rate and timing of surface uplift are needed. Within the Central Andes paleoelevation proxies are afflicted by either large uncertainties or reliance on assumptions about past climate-elevation histories (Barnes and Ehmer. 2009). This leads to paleoelevation data being unable to distinguish between the two main uplift models of the Andes; gradual uplift of the Andes from the Late Eocene due to crustal shortening/thickening, and rapid uplift in the Late Miocene due to large-scale mantle delamination (Barnes and Ehmer. 2009). Here we present a new paleoelevation tool based on the varying production rate of in situ cosmogenic isotopes with elevation. It can constrain surface uplift histories independently of paleoclimatic fluctuations, making it potentially more accurate than previous methods. Within the Atacama Desert Northern Chile, a stable arid-hyperarid climate has persisted over the last 23 Ma (Dunai et al. 2005). This has lead to exceptionally low erosion rates and high cosmogenic nuclide concentrations within alluvial boulders overlying the Pacific Planation Surface (PPS). In the Aroma Quebrada region, the PPS can be constrained as forming post 13.4 Ma, using underlying volcanics (Evenstar 2007). Alluvial boulders that lie on this PPS have high concentrations of cosmogenic He-3 that suggest deposition soon after surface formation. Comparing concentrations of cosmogenic 3He in the boulders to those calculated for varying uplift histories the timing of the uplift of the western margin of the Andes can be constrained. The models require the Pacific Planation Surface to reach at least 2/3 of its current elevation by 13.4 Ma. These results are not consistent with rapid uplift of the Andes due to mantle delamination in the Late Miocene but support progressive shortening and thickening of continental crust initiating in the Early Miocene or earlier.

Evenstar, Laura; Stuart, Finlay; Hartley, Adrian

2014-05-01

228

Geomorphic Characterization of the FortyMile Wash Alluvial Fan, Nye County, Nevada, In Support of the Yucca Mountain Project  

SciTech Connect

In the event of an unlikely volcanic eruption through the proposed high-level radioactive waste repository at Yucca Mountain, contaminated ash would be deposited in portions of the Fortymile Wash drainage basin and would subsequently be redistributed to the Fortymile Wash alluvial fan by fluvial processes. As part of an effort to quantify the transport of contaminated ash throughout the fluvial system, characterization of the Fortymile Wash alluvial fan is required, especially the spatial distribution of fluvial activity over time scales of repository operation, and the rates of radionuclide migration into different soils on the fan. The Fortymile Wash alluvial fan consists of extremely low relief terraces as old as 70 ka. By conducting soils-geomorphic mapping and correlating relative surface ages with available geochronology from the Fortymile Wash fan and adjacent piedmonts, we identified 4 distinct surfaces on the fan. Surface ages are used to predict the relative stability of different areas of the fan to fluvial activity. Pleistocene-aged surfaces are assumed to be fluvially inactive over the 10 kyr time scale, for example. Our mapping and correlation provides a map of the depozone for contaminated ash that takes into account long-term channel migration the time scales of repository operation, and it provides a geomorphic framework for predicting radionuclide dispersion rates into different soils across the fan. The standard model for vertical migration of radionuclides in soil is diffusion; therefore we used diffusion profiles derived from {sup 137}Cs fallout to determine infiltration rates on the various geomorphic surfaces. The results show a strong inverse correlation of the geomorphic surface age and diffusivity values inferred from the {sup 137}Cs profiles collected on the different surfaces of the fan.

Cline; De Long; Pelletier; Harrington

2005-09-06

229

Semi-Arid Landscapes: The Canary in the Climate-Change Coalmine (Invited)  

NASA Astrophysics Data System (ADS)

The balance between precipitation as a driving force of sediment transport (via hillslope erosional processes) or a resisting force (via increases in vegetation cover) is reflected by the landforms and denudation rates in semi-arid landscapes. While exact values vary, studies examining the relationship between land surface lowering and mean annual precipitation show a ';sweet spot' of peak denudation rates for semi-arid landscapes receiving ~300-500 mm precipitation/year. Ongoing and future climate change necessitates the investigation of how landscapes may respond as they move towards or away from this erosional threshold; semi-arid landscapes on the edge of ecohydrologic thresholds (e.g. treelines) may experience dramatic environmental changes as ongoing and future climate change alters ecosystems. Semi-arid landscapes are the equivalent to canaries in a coal-mine, and studying them advances understanding of how other sensitive landscapes may respond to climate change. Landforms, however, are a product of thousands to millions of years of climatic forcing. Direct measurement of both short and long-term erosion rates is complicated, and observations of modern erosional processes may not reflect the past. Over 10 years of environmental data collected in the heavily instrumented Dry Creek Experimental Watershed (DCEW) outside Boise, Idaho facilitates 2nd order analysis of climate-driven environmental variability across a large area (27 km2). Multi-scaled analyses relate runoff production from pedons to catchments, and erosion rates and processes from hillslopes to landforms, while prior mapping results (Poulos et al, 2012) allow application of results to similar semi-arid montane landscapes. Preliminary data reveal intriguing, but counterintuitive, feedbacks among soil properties, hillslope hydrology, ecology, and drainage development. Despite steeper slope angles, north-facing slopes have thicker soils than south-facing slopes, suggesting slower erosion rates. This conflicts with theories of hillslope processes which predict that erosion rates increase and soil thicknesses decrease with increasing slope angles. Could future increases in temperatures and decreased vegetation push north-facing slopes beyond a geomorphic tipping point, where their soils and drainages erode like south-facing slopes? Also, shallower soils and reduced plant cover on south-facing slopes appear to limit soil water storage and evapotranspiration, culminating in increased runoff and streamflow from these relatively drier ecosystems. What impact do these pedon- and hillslope-scale differences in runoff have on catchment-scale drainage erosion, incision and expansion? Finally, while landforms and erosion rates reflect, to some degree, the annual to centennial-scale climate conditions and precipitation events, episodic events such as wildfires exert a major control on erosion rates. Alluvial fans act as natural (albeit a bit leaky) sediment traps for hillslope erosion from 1st order drainage systems, while charcoal fragments in alluvial fan stratigraphic sequences provide both evidence of fire, and (through 14C dating) a means to estimate erosion rates. Ongoing fire studies in the DCEW, combined with surveys of alluvial fan sediment volumes, will reveal 1) the contribution of fire events to overall erosion rates, 2) variability in erosion rates between north and south facing slopes and 3) changes in Holocene fire activity with changes in climate.

Pierce, J. L.; Poulos, M. J.

2013-12-01

230

Glacier retreat as a result of climate warming and increased precipitation in the Tarim river basin, northwest China  

Microsoft Academic Search

The Tarim river basin, a river system formed by the convergence of nine tributaries, is the most heavily glacierized watershed in arid northwest China. In the basin, there are 11 665 glaciers with a total area of 19 878 km2 and a volume of 2313 km3. Glaciers in the basin play a significant role in the water resource system. It

Shiyin Liu; Yongjian Ding; Donghui Shangguan; Yong Zhang; Jing Li; Haidong Han; Jian Wang; Changwei Xie

2006-01-01

231

Rainbow Basin, CA mapping project  

NSDL National Science Digital Library

Rainbow Basin is just north of Barstow, CA, and is an excellent badlands-style exposure of the Barstow syncline in the Miocene Barstow Formation. In the first mapping class, their assignment is to map the basic geology of the basin, using a couple of distinctive marker beds within the Barstow Formation. Several faults postdate the fold, and three different ages of alluvial deposits occur within the basin. We camp in the nearby Owl Canyon campground, and spend three days in the field. More time could be spent with an introductory class, but three suffices to get most of the basin on the map. They are charged with writing up descriptions of the rock units they encounter. From the field map, students transfer information to an office copy, add a map explanation, and draw a cross-section through the map area. Mapping is done on a topographic map, specifically developed for the basin, with 10-foot contour intervals. This is a proprietary map, so permission is needed for its use.

Fryxell, Joan

232

Competing Interests and Concerns in the Rio Grande Basin: Mountain Hydrology, Desert Ecology, Climate Change, and Population Growth  

Microsoft Academic Search

In the mountainous American Southwest, the Rio Grande basin is a prime example of how conflicts, misconceptions, and competition regarding water can arise in arid and semi-arid catchments. Much of the Rio Grande runoff originates from snow fields in the San Juan Mountains of southern Colorado and the Sangre De Cristo Mountains of northern New Mexico, far from population centers.

A. Rango

2004-01-01

233

Vegetation ecology of Early Pennsylvanian alluvial fan and piedmont environments in southern New Brunswick, Canada  

Microsoft Academic Search

The vegetation ecology of Pennsylvanian upland\\/dryland regions is poorly known, despite its evolutionary significance. Here, fossil plant assemblages are described from well-drained alluvial fan\\/piedmont deposits in the uppermost Boss Point and Tynemouth Creek formations (late Yeadonian–Langsettian), southern New Brunswick. Beds record the northward building of a large alluvial fan complex over alluvial plain deposits in response to near-continuous sourceland uplift.

Howard J. Falcon-Lang

2006-01-01

234

ARID relative calibration experimental data and analysis  

NASA Technical Reports Server (NTRS)

Several experiments measure the orientation error of the ARID end-frame as well as linear displacements in the Orbiter's y- and z-axes. In each experiment the position of the ARID on the trolley is fixed and the manipulator extends and retracts along the Orbiter's y-axis. A sensor platform consisting of four sonars arranged in a '+' pattern measures the platform pitch about the Orbiter's y-axis (angle b) and yaw about the Orbiter's x-axis (angle alpha). Corroborating measurements of the yaw error were performed using a carpenter's level to keep the platform perpendicular to the gravity vector at each ARID pose being measured.

Doty, Keith L

1992-01-01

235

Attributes of an alluvial river and their relation to water policy and management  

PubMed Central

Rivers around the world are being regulated by dams to accommodate the needs of a rapidly growing global population. These regulatory efforts usually oppose the natural tendency of rivers to flood, move sediment, and migrate. Although an economic benefit, river regulation has come at unforeseen and unevaluated cumulative ecological costs. Historic and contemporary approaches to remedy environmental losses have largely ignored hydrologic, geomorphic, and biotic processes that form and maintain healthy alluvial river ecosystems. Several commonly known concepts that govern how alluvial channels work have been compiled into a set of “attributes” for alluvial river integrity. These attributes provide a minimum checklist of critical geomorphic and ecological processes derived from field observation and experimentation, a set of hypotheses to chart and evaluate strategies for restoring and preserving alluvial river ecosystems. They can guide how to (i) restore alluvial processes below an existing dam without necessarily resorting to extreme measures such as demolishing one, and (ii) preserve alluvial river integrity below proposed dams. Once altered by dam construction, a regulated alluvial river will never function as before. But a scaled-down morphology could retain much of a river's original integrity if key processes addressed in the attributes are explicitly provided. Although such a restoration strategy is an experiment, it may be the most practical solution for recovering regulated alluvial river ecosystems and the species that inhabit them. Preservation or restoration of the alluvial river attributes is a logical policy direction for river management in the future. PMID:11050220

Trush, William J.; McBain, Scott M.; Leopold, Luna B.

2000-01-01

236

Desert Pavement Process and Form: Modes and Scales of Landscape Stability and Instability in Arid Regions  

NASA Astrophysics Data System (ADS)

Desert pavements are recognized in arid landscapes around the world, developing via diminution of constructional/depositional landform relief and creating a 1-2 stone thick armor over a "stone free" layer. Surface exposure dating demonstrates that clasts forming the desert pavements are maintained at the land surface over hundreds of thousands of years, as aeolian fines are deposited on the land surface, transported into the underlying parent material and incorporated into accretionary soil horizons (e.g., the stone free or vesicular [Av] horizon). This surface armor provides long-term stability over extensive regions of the landscape. Over shorter time periods and at the landform-element scale, dynamic surficial processes (i.e., weathering, runoff) continue to modify the pavement form. Clast size reduction in comparison to underlying parent material, along with armoring and packing of clasts in pavements contribute to their persistence, and studies of crack orientations in pavement clasts indicate physical weathering and diminution of particle size are driven by diurnal solar insolation. Over geologic time, cracks form and propagate from tensile stresses related to temporal and spatial gradients in temperature that evolve and rotate in alignment with the sun's rays. Observed multimodal nature of crack orientations appear related to seasonally varying, latitude-dependent temperature fields resulting from solar angle and weather conditions. Surface properties and their underlying soil profiles vary across pavement surfaces, forming a landscape mosaic and controlling surface hydrology, ecosystem function and the ultimate life-cycle of arid landscapes. In areas of well-developed pavements, surface infiltration and soluble salt concentrations indicate that saturated hydraulic conductivity of Av horizons decline on progressively older alluvial fan surfaces. Field observations and measurements from well-developed desert pavement surfaces landforms also yield significantly lower infiltration rates, enhanced rates of overland flow characterized by high water:sediment ratios and reduced production of desert ecosystems. Consequently, regionally extensive pavement and significantly decreased infiltration over geologic time have resulted in widespread overland flow, elaborate drainage networks on alluvial and eolian-mantled bedrock landscapes, and channel incision and regional dissection of the pavement-mantled landforms. However, these once stable landscapes become progressively unstable with time, serving as sediment source areas for younger alluvial deposits (i.e., geologic life-cycle). Thus, regional dissection (instability) of these desert landscapes can be influenced by the intrinsic properties of pavement-mantled landscapes and not necessarily to external forces of climate change and tectonics.

Wells, Stephen G.; McFadden, Leslie D.; McDonald, Eric V.; Eppes, Martha C.; Young, Michael H.; Wood, Yvonne A.

2014-05-01

237

Thermal tracer tests for characterizing a shallow alluvial aquifer  

NASA Astrophysics Data System (ADS)

Using heat as an active tracer in different types of aquifers is a topic of increasing interest [e.g. Vandenbohede et al.; 2008, Wagner et al., 2013; Read et al., 2013]. In this study, we investigate the potential interest of coupling heat and solute tracer tests for characterization of a shallow alluvial aquifer. A thermal tracer test was conducted in the alluvial aquifer of the Meuse River, Belgium. The tracing experiment consisted in simultaneously injecting heated water and a dye tracer in a piezometer and monitoring the evolution of groundwater temperature and tracer concentration in the recovery well and in nine monitoring wells located according to three transects with regards to the main groundwater flow direction. The breakthrough curves measured in the recovery well showed that heat transfer in the alluvial aquifer is slower and more dispersive than solute transport. Recovery is very low for heat while in the same time it is measured as relatively high for the solute tracer. This is due to the fact that heat diffusion is larger than molecular diffusion, implying that exchange between groundwater and the porous medium matrix is far more significant for heat than for solute tracers. Temperature and concentrations in the recovery well are then used for estimating the specific heat capacity with the energy balance approach and the estimated value is found to be consistent with those found in the literature. Temperature breakthrough curves in other piezometers are contrasted with what would be expected in an ideal layered aquifer. They reveal strongly unequal lateral and vertical components of the transport mechanisms. By means of a numerical heat transport model, we provide a preliminary interpretation of these temperature breakthrough curves. Furthermore, these data could be included in the calibration of a complex heat transfer model for estimating the entire set of heat transfer parameters and their spatial distribution by inverse modeling.

Wildemeersch, Samuel; Klepikova, Maria; Jamin, Pierre; Orban, Philippe; Hermans, Thomas; Brouyère, Serge; Dassargues, Alain

2014-05-01

238

Use of composts in revegetating arid lands.  

National Technical Information Service (NTIS)

Compost has been suggested as a soil amendment for arid lands at the US Department of Energy's Hanford Site in southeastern Washington State. The operating contractor of the site, Westinghouse Hanford Company, requested that the Pacific Northwest Laborato...

C. A. Brandt, P. L. Hendrickson

1991-01-01

239

Deposition and early hydrologic evolution of Westwater Canyon wet alluvial-fan system  

SciTech Connect

The Westwater Canyon Member is one of several large, low-gradient alluvial fans that compose the Morrison Formation in the Four Corners area. Morrison fans were deposited by major laterally migrating streams entering a broad basin bounded by highlands to the west and south. The Westwater Canyon sand framework consists of a downfan succession of 1) proximal braided channel, 2) straight bed-load channel, 3) sinuous mixed-load channel, and 4) distributary mixed-load-channel sand bodies. Regional sand distribution and facies patterns are highly digitate and radiate from a point source located northwest of Gallup, New Mexico. Early ground-water flow evolution within the Westwater Canyon fan aquifer system can be inferred by analogy with Quaternary wet-fan deposits and by the interpreted paragenetic sequence of diagenetic features present. Syndepositional flow was controlled by the downfan hydrodynamic gradient and the high horizontal and vertical transmissivity of the sand-rich fan aquifer. Dissolution and transport of soluble humate would be likely in earliest ground water, which was abundant, fresh, and slightly alkaline. With increasing confinement of the aquifer below less permeable tuffaceous Brushy Basin deposits and release of soluble constituents from volcanic ash, flow patterns stabilized, and relatively more saline, uranium-rich ground water permeated the aquifer. Uranium mineralization occurred during this early postdepositional, semiconfined flow phase. Development of overlying Dakota swamps suggests a shallow water table indicative of regional dischare or stagnation. In either event, only limited downward flux of acidic water is recorded by local, bleached, kaolinized zones where the Westwater Canyon directly underlies the Dakota swamps. Subsequent ground-water flow phases have further obscured primary alteration patterns and caused local oxidation and redistribution of uranium.

Galloway, W.E.

1980-01-01

240

Geomorphologic, stratigraphic and sedimentologic evidences of tectonic activity in Sone-Ganga alluvial tract in Middle Ganga Plain, India  

NASA Astrophysics Data System (ADS)

The basement of the Ganga basin in the Himalayan foreland is criss-crossed by several faults, dividing the basin into several sub-blocks forming horsts, grabens, or half-grabens. Tectonic perturbations along basement faults have affected the fluvial regime and extent of sediment fill in different parts of the basin during Late Quaternary. The East Patna Fault (EPF) and the West Patna Fault (WPF), located in Sone-Ganga alluvial tract in the southern marginal parts of Middle Ganga Plain (MGP), have remained tectonically active. The EPF particularly has acted significantly and influenced in evolving the geomorphological landscape and the stratigraphic architecture of the area. The block bounded by the two faults has earlier been considered as a single entity, constituting a half-graben. The present investigation (by morpho-stratigraphic and sedimentologic means) has revealed the existence of yet another fault within the half-graben, referred to as Bishunpur-Khagaul Fault (BKF). Many of the long profile morphological characters (e.g., knick-zone, low width-depth ratio) of the Sone River at its lower reaches can be ascribed to local structural deformation along BKF. These basement faults in MGP lie parallel to each other in NE-SW direction.

Sahu, Sudarsan; Saha, Dipankar

2014-08-01

241

Global and continental changes of arid areas using the FAO Aridity Index over the periods 1951-1980 and 1981-2010  

NASA Astrophysics Data System (ADS)

An increase in arid areas and progressing land degradation are two of the main consequences of global climate change. In the 2nd edition of the World Atlas of Desertification (WAD), published by the United Nation Environment Program (UNEP) in 1997, a global aridity map was presented. This map was based on the Food and Agriculture Organization (FAO) Aridity Index (AI) that takes into account the annual ratio between precipitation (RR) and Potential Evapo-Transpiration (PET). According to the long-term mean value of this ratio, climate is therefore classified in hyper-arid (<0.05), arid (0.05-0.2), semi-arid (0.2-0.5), dry sub-humid (0.5-0.65), and humid (>0.65); a special case are cold climates, which occur if the mean annual PET is below 400 mm. In the framework of the 3rd edition of the WAD, we computed new global aridity maps to improve and update the old version that was based on a single dataset (CRU dataset, Climate Research Unit of University of East Anglia) related to the 1951-80 period only. We computed the AI on two different time intervals (1951-80 and 1981-2010) in order to account for shifts in classes between the two periods and we used two different datasets: PET from CRU (version 3.2), and precipitation from the global 0.5?x0.5? gridded monthly precipitation of the Global Precipitation Climatology Center (GPCC) of the Deutscher Wetterdienst (DWD). We used the GPCC Full Data Reanalysis Version 6.0, which showed a high reliability during many quality checks and is based on more stations than the CRU's precipitation counterpart. The results show that the "arid areas" (i.e. AI <0.5) globally increased from 28.4% to 29.6% and in Northern Hemisphere the cold climate areas decreased from 26.6% to 25.4%. Comparing the aridity maps of the two periods, the areas which most remarkably moved to lower AI values ("more arid" conditions) are: Canada, Brazil, the Mediterranean Region, Eastern Europe, almost all of Africa, the Middle East, Eastern China, Borneo, and Australia. At regional or country level, a shift of one class towards a "more arid" class can be found in Alaska (U.S.), Alberta (Canada), Patagonia (Argentina), Pernambuco (Brazil), Western Peru, Spain, the Southern Sahara and North-Eastern Kalahari deserts, Rajasthan and Madhya Pradesh (India), Mongolia, the Yang-Tze Basin (China), and the North-Eastern and South-Western Australian coasts. On the other hand, Central U.S., Paraguay and Northern Argentina, Scandinavia, Northern Australia, and Western China moved to a wetter climate in the last period. Due to the low data availability, we assumed that no changes took place in Antarctica, which is meant to be under a permanent ice cap, excluding the northernmost Graham Land.

Spinoni, Jonathan; Micale, Fabio; Carrao, Hugo; Naumann, Gustavo; Barbosa, Paulo; Vogt, Jürgen

2013-04-01

242

Depositional character of a dry-climate alluvial fan system from Palaeoproterozoic rift setting using facies architecture and palaeohydraulics: Example from the Par Formation, Gwalior Group, central India  

NASA Astrophysics Data System (ADS)

The ?20 m thick coarse-grained clastic succession in the basal part of Palaeoproterozoic Par Formation, Gwalior Group has been investigated using process-based sedimentology and deductive palaeohydraulics. Bounded between granitic basement at its base and shallow marine succession at the top, the studied stratigraphic interval represents products of an alluvial fan and its strike-wise co-existent braided river system that possibly acted as a tributary for the fan. Detailed facies, facies association analysis allowed identification of two anatomical parts for the fan system viz. proximal and mid fan. While thin proximal fan is represented by products of rock avalanche and hyperconcentrated flows with widely varying rheology, the mid fan is represented by products of sheet floods and flows within streamlets. The interpretation found support from palaeoslope estimation carried out on the fluvial part of the mid fan that plot dominantly within the alluvial fan field demarcated by Blair and McPherson (1994). Dry climatic condition suggested from dominance of stream flow over mass flow deposition within the Par alluvial fan. Strike-wise, the fan is discontinuous and juxtaposed with a braid plain system. In contrast to the fluvial part of fan system, the palaeoslope data from the braid plain system dominantly plot within the ‘natural depositional gap' defined by Blair and McPherson. A raised palaeoslope for the river systems, as suggested from Proterozoic braid plain deposits around the Globe, is found valid for the Par braid plain system as well. From preponderance of granular and sandy sediments within the alluvial fan and braid plain systems and a pervasive north-westward palaeocurrent pattern within the fluvial systems the present study infers a gently sloping bevelled source area in the south-southeast of the basin with occurrence of steep cliffs only locally.

Chakraborty, Partha Pratim; Paul, Pritam

2014-09-01

243

Preface paper to the Semi-Arid Land-Surface-Atmosphere (SALSA) Program special issue  

USGS Publications Warehouse

The Semi-Arid Land-Surface-Atmosphere Program (SALSA) is a multi-agency, multi-national research effort that seeks to evaluate the consequences of natural and human-induced environmental change in semi-arid regions. The ultimate goal of SALSA is to advance scientific understanding of the semi-arid portion of the hydrosphere-biosphere interface in order to provide reliable information for environmental decision making. SALSA approaches this goal through a program of long-term, integrated observations, process research, modeling, assessment, and information management that is sustained by cooperation among scientists and information users. In this preface to the SALSA special issue, general program background information and the critical nature of semi-arid regions is presented. A brief description of the Upper San Pedro River Basin, the initial location for focused SALSA research follows. Several overarching research objectives under which much of the interdisciplinary research contained in the special issue was undertaken are discussed. Principal methods, primary research sites and data collection used by numerous investigators during 1997-1999 are then presented. Scientists from about 20 US, five European (four French and one Dutch), and three Mexican agencies and institutions have collaborated closely to make the research leading to this special issue a reality. The SALSA Program has served as a model of interagency cooperation by breaking new ground in the approach to large scale interdisciplinary science with relatively limited resources.

Goodrich, D.C.; Chehbouni, A.; Goff, B.; MacNish, B.; Maddock, T.; Moran, S.; Shuttleworth, W.J.; Williams, D.G.; Watts, C.; Hipps, L.H.; Cooper, D.I.; Schieldge, J.; Kerr, Y.H.; Arias, H.; Kirkland, M.; Carlos, R.; Cayrol, P.; Kepner, W.; Jones, B.; Avissar, R.; Begue, A.; Bonnefond, J.-M.; Boulet, G.; Branan, B.; Brunel, J.P.; Chen, L.C.; Clarke, T.; Davis, M.R.; DeBruin, H.; Dedieu, G.; Elguero, E.; Eichinger, W.E.; Everitt, J.; Garatuza-Payan, J.; Gempko, V.L.; Gupta, H.; Harlow, C.; Hartogensis, O.; Helfert, M.; Holifield, C.; Hymer, D.; Kahle, A.; Keefer, T.; Krishnamoorthy, S.; Lhomme, J.-P.; Lagouarde, J.-P.; Lo, Seen D.; Luquet, D.; Marsett, R.; Monteny, B.; Ni, W.; Nouvellon, Y.; Pinker, R.; Peters, C.; Pool, D.; Qi, J.; Rambal, S.; Rodriguez, J.; Santiago, F.; Sano, E.; Schaeffer, S.M.; Schulte, M.; Scott, R.; Shao, X.; Snyder, K.A.; Sorooshian, S.; Unkrich, C.L.; Whitaker, M.; Yucel, I.

2000-01-01

244

Herbicide interchange between a stream and the adjacent alluvial aquifer  

USGS Publications Warehouse

Herbicide interchange between a stream and the adjacent alluvial aquifer and quantification of herbicide bank storage during high streamflow were investigated at a research site on the Cedar River flood plain, 10 km southeast of Cedar Rapids, Iowa. During high streamflow in March 1990, alachlor, atrazine, and metolachlor were detected at concentrations above background in water from wells as distant as 20, 50, and 10 m from the river's edge, respectively. During high streamflow in May 1990, alachlor, atrazine, cyanazine, and metolachlor were detected at concentrations above background as distant as 20, 50, 10, and 20 m from the river's edge, respectively. Herbicide bank storage took place during high streamflow when hydraulic gradients were from the river to the alluvial aquifer and the laterally infiltrating river water contained herbicide concentrations larger than background concentrations in the aquifer. The herbicide bank storage can be quantified by multiplying herbicide concentration by the "effective area" that a well represented and an assumed porosity of 0.25. During March 1990, herbicide bank storage values were calculated to be 1.7,79, and 4.0 mg/m for alachlor, atrazine, and metolachlor, respectively. During May 1990, values were 7.1, 54, 11, and 19 mg/m for alachlor, atrazine, cyanazine, and metolachlor, respectively. ?? 1994 American Chemical Society.

Wang, W.; Squillace, P.

1994-01-01

245

A comparison of Nannochloropsis salina growth performance in two outdoor pond designs: conventional raceways versus the ARID pond with superior temperature management  

SciTech Connect

The present study examines how climatic conditions and pond design affect the growth performance of microalgae. From January to April of 2011, outdoor batch cultures of Nannochloropsis salina were grown in three replicate 780 L conventional raceways, as well as in an experimental 7500 L ARID (Algae Raceway Integrated Design) pond. The ARID culture system utilizes a series of 8 to 20 cm deep basins and a 1.5 m deep canal to enhance light exposure and mitigate temperature variations and extremes. The ARID culture reached the stationary phase 27 days earlier than the conventional raceways, which can be attributed to its superior temperature management and shallower basins. On a night when the air temperature dropped to -9 °C, the water temperature was 18 °C higher in the ARID pond than in the conventional raceways. Lipid and fatty acid content ranged from 16 - 25 % and 5 - 15 %, respectively, as a percentage of AFDW. Palmitic, palmitoleic, and eicosapentaenoic acid comprised the majority of fatty acids. While the ARID culture system achieved nearly double the volumetric productivity relative to the conventional raceways (0.023 vs 0.013 g L-1day-1), areal biomass productivities were of similar magnitude in both pond systems (3.34 vs. 3.47 g m-2day-1), suggesting that the ARID pond design has to be further optimized, most likely by increasing the culture depth or operating at higher cell densities while maintaining adequate mixing.

Crowe, Braden J.; Attalah, Said; Agrawal, Shweta; Waller, Peter; Ryan, Randy; Van Wagenen, Jonathan M.; Chavis, Aaron R.; Kyndt, John; Kacira, Murat; Ogden, Kimberly L.; Huesemann, Michael H.

2012-10-01

246

Rivers turned to rock: Late Quaternary alluvial induration influencing the behaviour and morphology of an anabranching river in the Australian monsoon tropics  

NASA Astrophysics Data System (ADS)

Late Quaternary alluvial induration has greatly influenced contemporary channel morphology on the anabranching Gilbert River in the monsoon tropics of the Gulf of Carpentaria. The Gilbert, one of a number of rivers in this region, has contributed to an extensive system of coalescing low-gradient and partly indurated riverine plains. Extensive channel sands were deposited by enhanced flow conditions during marine oxygen isotope (OI) Stage 5. Subsequent flow declined, probably associated with increased aridity, however, enhanced runoff recurred again in OI Stages 4-3 (˜65-50 ka). Aridity then capped these plains with 4-7 m of mud. A widespread network of sandy distributary channels was incised into this muddy surface from sometime after the Last Glacial Maximum (LGM) to the mid Holocene during a fluvial episode more active than the present but less so than those of OI Stages 5 and 3. This network is still partly active but with channel avulsion and abandonment now occurring largely proximal to the main Gilbert flow path. A tropical climate and reactive catchment lithology have enhanced chemical weathering and lithification of alluvium along the river resulting in the formation of small rapids, waterfalls and inset gorges, features characteristic more of bedrock than alluvial systems. Thermoluminescence (TL) and comparative optically stimulated luminescence (OSL) ages of the sediments are presented along with U/Th ages of pedogenic calcrete and Fe/Mn oxyhydroxide/ oxide accumulations. They show that calcrete precipitated during the Late Quaternary at times similar to those that favoured ferricrete formation, possibly because of an alternating wet-dry climate. Intense chemical alteration of the alluvium leading to induration appears to have prevailed for much of the Late Quaternary but, probably due to exceptional dryness, not during the LGM. The result has been restricted channel migration and a reduced capacity for the channel to adjust and accommodate sudden changes in bedload. Consequent avulsions have caused local stream powers to increase by an order of magnitude, inducing knickpoint erosion, local incision and the sudden influx of additional bedload that has triggered further avulsions. The Gilbert River, while less energetic than its Pleistocene ancestors, is clearly an avulsive system, and emphasizes the importance in some tropical rivers of alluvial induration for reinforcing the banks, generating nickpoints, reworking sediment and thereby developing and maintaining an indurated and anabranching river style.

Nanson, Gerald C.; Jones, Brian G.; Price, David M.; Pietsch, Timothy J.

2005-09-01

247

RIVER TRANSPORT - INDUCED CHANGES IN CHEMICAL COMPOSITION OF ALLUVIAL GOLD (DOCUMENTED ON LOCALITIES THE WESTERN CARPATHIANS)  

Microsoft Academic Search

Alluvial gold is influenced by various physical, chemical and biological factors. As type- localities for study of changes in chemical composition of alluvial gold we chose Pukanec (Central Slovakia Neovolcanic Field) and Magurka and Ni?ná Boca (Nízke Tatry Mts). The most distinctive are morphological and chemical changes (dissolution and precipitation), the latter is most commonly represented by the formation of

B. BAHNA; A. SMIRNOV; M. CHOVAN; F. BAKOS

248

A. Reservoir Effects of Stream Channels DAM IMPACTS ON AND RESTORATION OF AN ALLUVIAL RIVER  

E-print Network

A. Reservoir Effects of Stream Channels DAM IMPACTS ON AND RESTORATION OF AN ALLUVIAL RIVER ­ RIO and reservoirs on alluvial rivers extends both upstream and downstream of the dam. Downstream of dams, both and sediment retention. Prior to dam construction, the Rio Grande was a wide, sandy braided river. Following

Julien, Pierre Y.

249

Interpreting alluvial archives: sedimentological factors in the British Holocene fluvial record  

Microsoft Academic Search

A Holocene alluvial archive of 506 dated units for Great Britain is analysed in terms of the sedimentation styles involved. The database is classified by sedimentation unit (channel sediments, palaeochannel fills, floodplain surface sediments, floodbasins and colluvial deposits) and alluvial ensemble (fans and cones, upland gullies and streams, braided systems and active\\/inactive meandering and anastomosing systems).Floodplain, palaeochannel and floodbasin sediments

J. Lewin; M. G. Macklin; E. Johnstone

2005-01-01

250

The Late Quaternary biogeographic histories of some Great Basin mammals (western USA)  

Microsoft Academic Search

The Great Basin of arid western North America provides one of the most detailed late Pleistocene and Holocene mammal records available for any part of the world, though the record is by far strongest for small mammals. Of the 35 genera of now-extinct North American Pleistocene mammals, 19 are known to have occurred in the Great Basin, a list that

Donald K. Grayson

2006-01-01

251

Groundwater replenishment analysis by using natural isotopes in Ejina Basin, Northwestern China  

Microsoft Academic Search

The Ejina Basin underlying complex aquifers is located in the lower reaches of the Heihe River with an arid climate and 40 mm mean annual precipitation. As the balance of the natural ecosystem in the Ejina Basin is fragile and easily upset, it is very important to estimate and rationally use the limited groundwater resources to maintain the balance. Water samples

Yinghua Zhang; Y. Wu; J. Su; X. Wen; F. Liu

2005-01-01

252

Boundary Layer Evolution within a Canyonland Basin. Part I: Mass, Heat, and Moisture Budgets from Observations  

Microsoft Academic Search

Individual terms of the mass, heat, and moisture budget equations are evaluated for an atmospheric control volume in Colorado's Sinbad Basin using tethered balloon and surface energy budget data obtained during a 16.5-h period on 15 16 July 1988. The basin was chosen for its simple topography and arid climate, which simplified the evaluation of some of the budget terms.

C. David Whiteman; Thomas B. McKee; J. C. Doran

1996-01-01

253

Making sense of the mixed alluvium in the Yucca Flat basin  

Microsoft Academic Search

In an attempt to unravel the stratigraphy of the mixed alluvium in the Yucca Flat basin, the author reviewed lithologic descriptions for most of the exploratory and emplacement holes in northern Yucca Flat and identified seven types of alluvial deposits. These lithostratigraphic units were defined by the percentage of detritus derived from the three main source terranes: Paleozoic clastic and

Wagoner

1987-01-01

254

Sedimentology and geochemistry of carbonates from lacustrine sequences in the Madrid Basin, central Spain  

Microsoft Academic Search

Lacustrine and alluvial carbonate facies have been investigated in Middle Miocene successions of the western side of the Madrid Basin in order to evaluate paleoenvironments in which carbonates formed. Carbonate facies are varied and include: (1) calcrete and dolocrete; (2) pond deposits; (3) lake margin dolostone; (4) mudflat carbonate; and (5) open-lake carbonate facies. The dominant mineralogy of these is

J. P. Calvo; B. F. Jones; M. Bustillo; R. Fort; A. M. Alonso Zarza; C. Kendall

1995-01-01

255

A Mapping and Geographical Analysis of Japanese Gardens in the Kyoto Basin  

Microsoft Academic Search

This study analyzes the location of 164 renowned Japanese gardens in the Kyoto basin, that is the Kamogawa alluvial fan and the Katsuragawa flood plain. The gardens were mapped using Geographic Information System (GIS) technology. The mapped data indicate that physiographic environments constrain the location of the gardens. Rock gardens (karesansui type gardens) are located accross the whole area of

Takayuki Ogata; Wei li; Shöji Yamada

2010-01-01

256

Extended stratigraphy, palynology and depositional environments record the initiation of the Himalayan Gyirong Basin (Neogene China)  

E-print Network

Extended stratigraphy, palynology and depositional environments record the initiation, a basin induced by east­west extension in the Himalayas of south- ern Tibet. We document the conglomeratic, have revealed three depositional environ- ments for the deposition of the studied section. (1) Alluvial

Utrecht, Universiteit

257

Water harvesting techniques for small communities in arid areas.  

PubMed

Limited water resources exist in numerous remote indigenous settlements around Australia. Indigenous people in these communities are still living in rudimentary conditions while their urban counterparts have full amenities, large scale water supplies and behavioral practices which may not be appropriate for an arid continent but are supported by extensive infrastructure in higher rainfall coastal areas. As remote indigenous communities continue to develop, their water use will increase, and in some cases, costly solutions may have to be implemented to augment supplies. Water harvesting techniques have been applied in settlements on a small scale for domestic and municipal purposes, and in the large, broadacre farm setting for productive use of the water. The techniques discussed include swales, infiltration basins, infiltration trenches and "sand dam" basins. This paper reviews the applications of water harvesting relevant to small communities for land rehabilitation, landscaping and flood control. Landscaping is important in these communities as it provides shelter from the sun and wind, reduces soil erosion and hence reduced airborne dust, and in some cases provides food and nutrition. Case studies of water harvesting systems applied in the Pilbara Region, Western Australia for landscaping around single dwellings in Jigalong and Cheeditha, in a permaculture garden in Wittenoon and at a college and carpark in Karratha are described. PMID:11700659

Yuen, E; Anda, M; Mathew, K; Ho, G

2001-01-01

258

Quaternary Faults and Basin-fill Sediments of the Las Vegas Basin, Southern Nevada  

NASA Astrophysics Data System (ADS)

The N-S elongated extensional Las Vegas basin, southern Nevada, contains 100's of meters of Cenozoic basin-fill sediments that are cut by several Quaternary (Q) faults. These faults define or influence the basin geometry. The basin is generally an asymmetrical half graben defined by the W-dipping, Q Frenchman Mountain fault (FMF) along its E side and a series of smaller offset E-dipping faults to the W. The N terminus of the basin is controlled by the Las Vegas Valley shear zone, along which the majority of the offset occurred prior to the Q. Here, we asses the influence of the Q faults on the distribution of the sedimentary units. Well, exposure, seismic reflection and seismic refraction data show that sedimentary units of different grain sizes or seismic velocity dominate different parts of the basin. Sections dominated by coarse clastic deposits occupy a narrow area along the E side of the basin. Coarse clastic sediments are mixed with finer grained sediments in a broader area along the W side of the basin. Based on provenance and alluvial fan distribution, the coarse deposits along the E side of the basin appear to be trapped in close proximity to the W-dipping FMF. The coarse-grained deposits along the opposite, W side of the basin, are sourced from the nearby Spring Mountains. Because of the structural asymmetry of the basin, these sediments traveled farther from their source area than those on the E side. Some of these E-dipping faults influence the depth to Paleozoic bedrock and some faults form small sub-basins filled with finer grained sediments. Along a WNW trend near the center of the basin and near the present-day Las Vegas Wash, a change in the grain size distribution occurs up stratgraphic section: continuous clay layers are less common and coarse-grained deposits are more common. This difference may reflect a change from internal drainage early in the basin history to external drainage through the Las Vegas Wash in the latter history of the basin-fill sedimentation. This interpretation implies that the FMF was breached by a wash connected to the Colorado River drainage system during basin development. The basin fill deposits suggest an early history of alluvial fan dominated deposits showing internal drainage. That depositional system was followed by E- and W-sloping alluvial fans cut by a NW-trending external drainage system that probably flowed to the Colorado River. The greatest structural influence on sediment distribution was from the Q FMF on the E side of the basin and the dominantly Miocene Las Vegas Valley shear zone on the north, but the structural influence is reduced as Colorado River system and base level imposes on the basin up section.

Taylor, W. J.; Fossett, E.; Luke, B.; Snelson, C.; Rasmussen, T.; McCallen, D.; Rodgers, A.; Louie, J.

2003-12-01

259

Soil texture controls vegetation biomass and soil organic carbon storage in arid desert grassland in the middle of Hexi Corridor region of northwest China  

NASA Astrophysics Data System (ADS)

Soil texture may play an important role in controlling vegetation distribution pattern and net primary production, as well as soil organic carbon (SOC) concentration and stock in arid desert grassland ecosystem. However, little information is available in the current literature on the occurrence and extent of these textural effects in arid desert grasslands in northwest China. The main objective of this study was to quantify the relationships between soil texture (silt + clay) and above-and below-ground biomass, SOC concentration and stock in arid Hexi corridor desert grasslands of northwest China. Above-and below-ground biomass were investigated and SOC concentration, bulk density, stone content, and soil particle size distribution at the seven layers of 100cm profile were determined in the selected 32 grassland sites located in the similar topographical units (alluvial-diluvial fans) in the study area. The results showed that above-ground biomass was higher than below-ground biomass, with a mean value of 0.67 in the below-ground biomass / above-ground biomass ratio (R/S). More than 95% of below-ground biomass distributed in the top 30 cm depth. Spatially, desert grassland vegetation biomass was positively related to soil sit+clay content. The mean SOC density in the 0-100 cm depth was 2.94 kg m-2 in the arid desert grasslands. SOC concentrations and stocks were positively and significantly related to silt+clay content for the seven soil layers sampled up to a depth of 100 cm. Soil silt+clay content explained 42%-79% of the variation in SOC stocks. In conclusion, soil texture appeared to have an important impact on the vegetation productivity and distribution pattern, and is an important controlling factor of SOC stocks in arid Hexi Corridor grassland soils. Keywords: soil texture, vegetation biomass, SOC stock, arid desert grassland, northwest China

su, Yong-zhong

2014-05-01

260

Comparison of planform multi-channel network characteristics of alluvial and bedrock constrained large rivers  

NASA Astrophysics Data System (ADS)

The Mekong River in northern Cambodia is an multi-channel mixed bedrock-alluvial river but it was poorly researched until present. Preliminary study of the Mekong geomorphology was conducted by gathering existing knowledge of its geological and tectonic settings, specific riparian vegetation and ancient alluvial terraces in which the river has incised since the Holocene. Altogether this process has allowed a geomorphological portrait of the river to be composed within the Quaternary context. Following this outline, the planform characteristics of the Mekong River network are compared, using analysis of channel network and islands configurations, with the fluvial patterns of the Orange River (South Africa), Upper Columbia River (Canada) and the Ganga River (India, Bangladesh). These rivers are selected as examples of multi-channel mixed bedrock alluvial, anastomosed alluvial and braided alluvial rivers respectively. Network parameters such as channel bifurcation angles asymmetry, sinuosity, braid intensity and island morphometric shape metrics are compared and contrasted between bedrock and alluvial systems. In addition, regional and local topographic trend surfaces produced for each river planform help explain the local changes in river direction and the degree of anastomosis, and distinguish the bedrock-alluvial rivers from the alluvial rivers. Variations between planform characteristics are to be explained by channel forming processes and in the case of mixed bedrock-alluvial rivers mediated by structural control. Channel metrics (derived at the reach-scale) provide some discrimination between different multi-channel patterns but are not always robust when considered singly. In contrast, island shape metrics (obtained at subreach-scale) allow robust discrimination between alluvial and bedrock systems.

Carling, P. A.; Meshkova, L.; Robinson, R. A.

2011-12-01

261

Exploration in the Ombilin Intermontane Basin, West Sumatra  

SciTech Connect

The Ombilin Basin is a Tertiary intermontane basin located within the Barisan Mountain Range of Sumatra. Oil exploration commenced in the Ombilin Basin in the early 1980s when geological mapping was carried out, a synthetic aperture radar survey was flown, and a basin-wide geophysical survey was completed. This effort led to the drilling of Sinimar No. 1 to a total depth 3020 m. Sinimar No. 1 was a historic well in Indonesia`s oil industry since it was the first oil exploration well drilled in the Ombilin Basin and also the first well drilled in an intermontane basin in Indonesia. Oil, gas and condensate was tested in the well. An integrated interpretation of the well, geophysical and outcrop data indicates that despite its small areal size (30 km x 50 km), the Ombilin Basin is a deep pull-apart basin containing up to 4500 m of Tertiary sediments, ranging in age from Middle Eocene to Early Miocene. The basin currently is in an intermontane basin structural setting but it was also an intermontane basin during its Early Tertiary depositional history. During the Eocene, alluvial fans and massive debris flows were deposited on the basin margins and a large lake occupied the basin center. Fluvial deposition occurred in the basin during the Oligocene followed by deposition of marine shales, sandstones, and isolated reefs during the Miocene. Although the Ombilin Basin is located within Sumatra`s magmatic arc and is partially covered by volcanics from extinct and active volcanoes, the subsurface temperature gradients of 1.62 deg. F/100 ft. recorded in Sinimar No. I and 1.47 deg F/100 ft. measured in a deep (670 m) coal exploration core hole are significantly cooler than the average subsurface temperature gradients in the Sumatra back-arc basins. Organic-rich Eocene lacustrine shales are the likely source rocks for the hydrocarbons tested in Sinimar No. 1 and the oil seeps located along the basin margins.

Koning, T. [Texaco Overseas (Nig.) Petroleum Co., Lagos (Nigeria)

1996-12-31

262

Exploration in the Ombilin Intermontane Basin, West Sumatra  

SciTech Connect

The Ombilin Basin is a Tertiary intermontane basin located within the Barisan Mountain Range of Sumatra. Oil exploration commenced in the Ombilin Basin in the early 1980s when geological mapping was carried out, a synthetic aperture radar survey was flown, and a basin-wide geophysical survey was completed. This effort led to the drilling of Sinimar No. 1 to a total depth 3020 m. Sinimar No. 1 was a historic well in Indonesia's oil industry since it was the first oil exploration well drilled in the Ombilin Basin and also the first well drilled in an intermontane basin in Indonesia. Oil, gas and condensate was tested in the well. An integrated interpretation of the well, geophysical and outcrop data indicates that despite its small areal size (30 km x 50 km), the Ombilin Basin is a deep pull-apart basin containing up to 4500 m of Tertiary sediments, ranging in age from Middle Eocene to Early Miocene. The basin currently is in an intermontane basin structural setting but it was also an intermontane basin during its Early Tertiary depositional history. During the Eocene, alluvial fans and massive debris flows were deposited on the basin margins and a large lake occupied the basin center. Fluvial deposition occurred in the basin during the Oligocene followed by deposition of marine shales, sandstones, and isolated reefs during the Miocene. Although the Ombilin Basin is located within Sumatra's magmatic arc and is partially covered by volcanics from extinct and active volcanoes, the subsurface temperature gradients of 1.62 deg. F/100 ft. recorded in Sinimar No. I and 1.47 deg F/100 ft. measured in a deep (670 m) coal exploration core hole are significantly cooler than the average subsurface temperature gradients in the Sumatra back-arc basins. Organic-rich Eocene lacustrine shales are the likely source rocks for the hydrocarbons tested in Sinimar No. 1 and the oil seeps located along the basin margins.

Koning, T. (Texaco Overseas (Nig.) Petroleum Co., Lagos (Nigeria))

1996-01-01

263

A semi-distributed, physics-based hydrologic model using remotely sensed and Digital Terrain Elevation Data for semi-arid catchments  

Microsoft Academic Search

A practical, hydrologic model (DPHM-RS) is developed for the semi-arid climate of the Canadian Prairies that could adequately account for a river basin's terrain features by sub-dividing it to sub-basins of uneven shapes and sizes (semi-distributed) based on topographic information derived from the digital terrain elevation (DTED) data. Even though computationally modest, DPHM-RS is scientifically vigorous, can effectively assimilate remotely

Getu Fana Biftu

2004-01-01

264

The Tabernas alluvial fan and lake system, southeast Spain: applications of mineral magnetic and pedogenic iron oxide analyses towards clarifying the Quaternary sediment sequences  

NASA Astrophysics Data System (ADS)

Mineral magnetic and soil iron oxide data are applied to questions of relative age correlation of alluvial fans and lake sediments in the Tabernas basin, southeast Spain, within a context of interaction between tectonics and climatic change. Within the Tabernas basin, the sediment sequences and morphological evolution of late Quaternary alluvial fans suggest climatic change as the primary control. The fans toe out at the upper margins of a former lake, created in response to tectonic uplift. Magnetic and iron oxide data from soils, particularly dithionite-extractable iron (Fe d), and frequency-dependent magnetic susceptibility ( ?FD%) accord with the relative age relationships suggested by more conventional field-based geomorphic observations. Magnetic data from the lake sediments suggest the main provenance characteristics of the sediments, but also reveal a shift in sediment sources towards the end of the lake period (probably during the late Pleistocene) to sediment supplied from a more active fluvial system from soil erosion within the Sierra de los Filabres part of the catchment. Hence, although the locations of the fans and the existence of the lake relate primarily to tectonics, the fan sequences themselves appear to be primarily climatically controlled, and there is evidence of a climatic influence over the source of sediment input into the lake during the late Pleistocene.

Harvey, Adrian M.; Foster, Gez; Hannam, Jack; Mather, Anne E.

2003-02-01

265

Sedimentology and climatic environment of alluvial fans in the martian Saheki crater and a comparison with terrestrial fans in the Atacama Desert  

NASA Astrophysics Data System (ADS)

The deflated surfaces of the alluvial fans in Saheki crater reveal the most detailed record of fan stratigraphy and evolution found, to date, on Mars. During deposition of at least the uppermost 100 m of fan deposits, discharges from the source basin consisted of channelized flows transporting sediment (which we infer to be primarily sand- and gravel-sized) as bedload coupled with extensive overbank mud-rich flows depositing planar beds of sand-sized or finer sediment. Flow events are inferred to have been of modest magnitude (probably less than ?60 m3/s), of short duration, and probably occupied only a few distributaries during any individual flow event. Occasional channel avulsions resulted in the distribution of sediment across the entire fan. A comparison with fine-grained alluvial fans in Chile’s Atacama Desert provides insights into the processes responsible for constructing the Saheki crater fans: sediment is deposited by channelized flows (transporting sand through boulder-sized material) and overbank mudflows (sand size and finer) and wind erosion leaves channels expressed in inverted topographic relief. The most likely source of water was snowmelt released after annual or epochal accumulation of snow in the headwater source basin on the interior crater rim during the Hesperian to Amazonian periods. We infer the Saheki fans to have been constructed by many hundreds of separate flow events, and accumulation of the necessary snow and release of meltwater may have required favorable orbital configurations or transient global warming.

Morgan, A. M.; Howard, A. D.; Hobley, D. E. J.; Moore, J. M.; Dietrich, W. E.; Williams, R. M. E.; Burr, D. M.; Grant, J. A.; Wilson, S. A.; Matsubara, Y.

2014-02-01

266

Seismic Response of Alluvial Valleys to SH Waves  

SciTech Connect

This paper presents a theoretical study on the seismic response of alluvial valleys. The considered model consists of a two-dimensional elastic inclusion of arbitrary shape embedded in a stiffer half-plane excited by vertically or obliquely incident SH waves. Computations are conducted using a procedure based on the boundary element method. As known, this numerical technique is well suited to deal with wave propagation in infinite media as it avoids the introduction of fictitious boundaries and reduces by one the dimensions of the problem. This provides significant advantages from a computational point of view. A one-dimensional closed form solution is also used for comparison, and the most significant differences between the results obtained using the two methods are highlighted.

Ausilio, Ernesto; Conte, Enrico; Dente, Giovanni [Dipartimento di Difesa del Suolo, Universit della Calabria (Italy)

2008-07-08

267

The measurement of total sediment load in alluvial streams  

USGS Publications Warehouse

The measurement of the total sediment load transported by streams that flow in alluvial channels has been a perplexing problem to engineers and geologists for over a century. Until the last decade the development of equipment to measure bed load and suspended load was carried on almost independently, and without primary consideration of the fundamental laws governing the transportation of fluvial sediments. French investigators during the nineteenth century described methods of measurement and a mathematical approach for computing the rate of bed-load movement. The comprehensive laboratory investigations by Gilbert early in this century provided data that are still being used for studies of sediment transport. Detailed laboratory investigations of bed-load movement conducted during the last two decades by a number of investigators have resulted in the development of additional mathematical formulas for computing rates of bed-load movement. Likewise, studies of turbulent flow have provided the turbulence suspension theory for suspended sediment as it is known today.

Benedict, P.C.; Matejka, D.Q.

1953-01-01

268

Estimating contaminant attenuation half-lives in alluvial groundwater systems  

SciTech Connect

One aspect of describing contamination in an alluvial aquifer is estimating changes in concentrations over time. A variety of statistical methods are available for assessing trends in contaminant concentrations. We present a method that extends trend analysis to include estimating the coefficients for the exponential decay equation and calculating contaminant attenuation half-lives. The conceptual model for this approach assumes that the rate of decline is proportional to the contaminant concentration in an aquifer. Consequently, the amount of time to remove a unit quantity of the contaminant inventory from an aquifer lengthens as the concentration decreases. Support for this conceptual model is demonstrated empirically with log-transformed time series of contaminant data. Equations are provided for calculating system attenuation half-lives for non-radioactive contaminants.

Tardiff, Mark F.; Katzman, Danny

2007-03-13

269

Methodologies for hydraulic hazard mapping in alluvial fan areas  

NASA Astrophysics Data System (ADS)

Hydraulic hazards in alluvial fan areas are mainly related to torrential floods and debris flows. These processes are characterized by their fast time evolution and relevant sediment load. Rational approaches for the estimation of hazard levels in flood-prone areas make use of the maps of depth and velocity, which are provided by numerical simulations of the event. This paper focuses on national regulations regarding quantitative debris-flow hazard mapping and compares them to a simple conceptual model for the quantification of the hazard levels on the basis of human stability in a flood. In particular, the proposed method takes into account, in a conceptual fashion, both the local slope and the density of the fluid, that are crucial aspects affecting stability for processes in mountain environments. Physically-based hazard criteria provide more comprehensible and objective maps, increasing awareness among stakeholders and providing more acceptable constraints for land planning.

Milanesi, L.; Pilotti, M.; Ranzi, R.; Valerio, G.

2014-09-01

270

S2Project: Near-fault earthquake ground motion simulation in the Sulmona alluvial basin  

Microsoft Academic Search

Recently the Italian Department of Civil Protection (DPC), in cooperation with Istituto Nazionale di Geofisica e Vulcanologia (INGV) has promoted the 'S2' research project (http:\\/\\/nuovoprogettoesse2.stru.polimi.it\\/) aimed at the design, testing and application of an open-source code for seismic hazard assessment (SHA). The tool envisaged will likely differ in several important respects from an existing international initiative (Open SHA, Field et

E. Faccioli; M. Stupazzini; F. Galadini; S. Gori

2008-01-01

271

Late Holocene Soil Stratigraphy and Geochronology of Alluvial Sedimentation in the Sonoran Desert, Arizona  

NASA Astrophysics Data System (ADS)

The integration of soil stratigraphic investigations and radiocarbon dating at two sites in combination with geomorphic mapping at scales of 1:50k and 1:5k offer insight to the timing and magnitude of alluvial sedimentation during the late Holocene within the Sonoran Desert near Yuma, Arizona. Mapping at 1:50k was performed over an area of 3400 km2 and alluvial landforms were labeled Qf1 to Qf5, from oldest to youngest, using 1- and 5-meter resolution satellite imagery within the U.S. Army Yuma Proving Ground (YPG). Approximately 70% of the identified landforms within YPG are Quaternary alluvial fans, alluvial plains, and active washes, whereas the other 30% consist of mountain highlands, pediments, and badlands. In the southwest portion of YPG near Muggins Mountains, alluvial fan terraces (Qf4) positioned 0.5 m above active washes are characterized as having moderate bar-and-swale microtopography, moderately developed desert pavement, and a Av/ Bw/ Cky/ Cky1/ Cky2/ Cky3 gravelly soil profile. A large piece of charcoalized Ironwood ( Olneya tesota) was recovered from a depth of 0.75 m and yielded three AMS 14C dates that range from 3330 to 2860 cal yr B.P. Geomorphic mapping at a scale of 1:5k indicates that in an area of 25 km2 at the site, the distribution of late Holocene alluvial fan terraces comprise 17% of the surrounding Quaternary alluvium. Similar aged alluvial features were observed about 70 km to the north near South Trigo Peak at YPG. Terraces of a broad and flat alluvial plain positioned 0.5 m above active channels are characterized as having moderate bar- and-swale microtopography, poorly developed desert pavement, and a AC/ C/ Bwkb1/ Bwk1b2/ Bwk2b2/ BCkb2/ Bwkb3 sandy soil profile. A terrestrial gastropod shell ( Lymnea sp.) fragment was recovered from a depth of 0.5 m and yielded an AMS 14C date of 2360-2310 cal yr B.P. Additional geomorphic mapping at 1:5k shows that in an area of 30 km2, the distribution of late Holocene alluvial plain terraces and equivalent alluvial fans include 35% of the surrounding Quaternary alluvium. Of the total Quaternary alluvium identified at 1:50k, 10% of the landforms consist of gravelly alluvial fans and sandy alluvial plains deposited between 3330 and 2310 cal yr B.P. The numerical ages and associated soil development provide evidence of regional alluvial sedimentation near Yuma, Arizona, and provides well constrained geomorphic data for paleoclimatic modeling in the Sonoran Desert during the late Holocene.

Bacon, S. N.; McDonald, E. V.; Dalldorf, G. K.; Caldwell, T. G.

2007-12-01

272

Miocene fluvial-tidal sedimentation in a residual forearc basin of the Northeastern Pacific Rim: Cook Inlet, Alaska case study  

SciTech Connect

Cook Inlet in southern Alaska represents a Cenozoic residual forearc basin in a convergent continental margin, where the Pacific Plate is being subducted beneath the North American Plate. This basin accumulated the >6,700-m-thick, mainly nonmarine, Eocene-Pliocene Kenai Group. These rocks contain biogenic coal-bed methane estimated to be as high as 245 TCF. Lignites to subbituminous coals with subsurface R{sub o} ranging from 0.38 to 0.73 percent and the stage of clay-mineral diagenesis and expandibility indicate a thermally {open_quotes}cool{close_quotes} basin. Miocene Tyonek and Beluga Formations compose 65 percent (>4,300 m thick) of the Kenai Group. The Tyonek includes conglomeratic sandstones, siltstones, mudstones, coals, and carbonaceous shales, interpreted as braided- stream deposits. These fluvial deposits are interbecided with burrowed, lenticular, and flaser-bedded sandstones, siltstones, and mudstones, interpreted as tidal deposits. Tyonek framework conglomerates formed in wet alluvial fans incised on paleovalleys of the Chugach terrane. Coal-forming mires are well developed on abandoned braided-stream deposits. Tyonek drainages formed in high-gradient alluvial plains inundated by tides similar to environments in the modern upper Cook Inlet. The upper Miocene Beluga consists of sandstones, siltstones, mudstones, carbonaceous shales, and coals deposited in meandering (low sinuosity) and anastomosed fluvial systems. These fluvial deposits alternated vertically with deposits of coal-forming mires. The Beluga drainages formed in low-gradient alluvial plains. The high-gradient Tyonek alluvial plain was probably controlled by provenance uplift and eustatic change, whereas the low-gradient Beluga alluvial plain was influenced by subdued provenance uplift and rapid basin subsidence. Rapid sedimentation on both these low- and high-gradient alluvial plains, which kept up with subsidence, produced a thermally {open_quotes}cool{close_quotes} basin.

Stricker, G.D.; Flores, R.M. [Geological Survey, Denver, CO (United States)

1996-12-31

273

Management implications of the ecology of free-roaming horses in semi-arid ecosystems of the western United States  

USGS Publications Warehouse

Compared to other ungulates of North America, free-roaming horses (Equus caballus) possess a unique evolutionary history that has given rise to a distinct suite of behavioral, morphological, and physiological traits. Because of their unique combination of cecal digestion, an elongate head with flexible lips, and non-uniform use of the landscape, horses represent a unique disturbance agent in semi-arid ecosystems of the western United States. Consequently, it is inappropriate to assume that influences of horses on the structure, composition, function, and pattern of arid and semi-arid ecosystems will mirror influences of cattle or other artiodactyls. Although management areas for free-roaming horses occupy 18.6 million ha of land across western North America, we know relatively little about how western ecosystems and their components have responded to this uniquely managed ungulate. I draw on my research of horse habitats in the western Great Basin (U.S.A.) to examine predictions of horses' unique influence, and advocate for continued research to refine our understanding of synecological relationships among horses and diverse ecosystem components in arid and semi-arid regions.

Beever, Erik A.

2003-01-01

274

An aridity index defined by precipitation and specific humidity  

NASA Astrophysics Data System (ADS)

SummaryThe United Nations Environmental Programme (UNEP), defined an aridity index (AI) by the ratio of the annual precipitation and potential evapotranspiration (PET) totals. In this work, specific humidity was used instead of PET and a new aridity index (Iq) has been defined using the ratio of annual precipitation totals and annual mean specific humidity (Sh). As shown in this study, Sh can be easily computed with very high accuracy (3.569% error rate) with mean temperature, relative humidity and local pressure which are most commonly and widely measured meteorological data. The single point correlation graph of Sh which shows the entrance of aridity through the South Eastern Anatolia Region into Turkey and the distribution of the aridity over Turkey explains the relationship with Sh and aridity. According to the common and different aspects of arid zones found with AI, Iq and Erinç aridity index (Im), Iq found to be applicable for monitoring climate change and distribution of arid zones.

Sahin, Sinan

2012-06-01

275

Extent and source of saltwater intrusion into the alluvial aquifer near Brinkley, Arkansas, 1984  

USGS Publications Warehouse

An approximate area of 56 sq mi of the alluvial aquifer just north of Brinkley, Arkansas, has been contaminated by saltwater (chloride concentration > or = 50 mg/L) intruded from underlying aquifers. The contamination was mapped from water quality data for 217 wells. Saltwater problems appear to have spread rapidly in the alluvial aquifer since the late 1940's. Chemical comparisons indicate that the alluvial aquifer was contaminated by water from the Sparta aquifer which in turn was contaminated by the underlying Nacatoch aquifer. The possibility of intrusion into the alluvial aquifer through abandoned oil and gas test wells was investigated but no evidence could be found to support this possibility. Upward movement into the alluvial aquifer from the underlying Sparta aquifer through the thinned or absent Jackson confining unit appears to be the principal reason for saltwater in the alluvial aquifer. Increased withdrawals of water from the alluvial aquifer for irrigation and public supply appear to have contributed to this upward movement. (Author 's abstract)

Morris, E. E.; Bush, W. V.

1986-01-01

276

The plight of arid land agriculture  

SciTech Connect

This book analyses the problems of the agricultural environment worldwide and possible solutions. Problems covered include the following: famines caused by agricultural land mismanegment in Subsaharan Africa and population increase; improved productivity leading to salinity, erosion, and water depletion; toxic wastes; loging, deforestation, and over-grazing. Agricultural practices, both ancient and modern, in arid lands are described. Food crops suited for arid lands, potential industrial crops, oil extraction from seed and rubber extraction, and biomass as a source of energy are discussed in different chapters. Finally the book deals with optimization of water use, prevention of salinization, and the prospect of global warming.

Hinman, C. W.; Hinman, K.W.

1992-01-01

277

Remote sensing of threshold conditions in an arid ecosystem  

NASA Astrophysics Data System (ADS)

Land management in the arid southwestern USA increasingly addresses thresholds in response to recent concepts adopted by private and public lands agencies and conservation organizations. Vegetation in arid rangelands typically presents as distinctive mosaics of vegetation patches, which persist in dynamic equilibrium with the abiotic environment and facilitative-competitive interactions between organisms. Theory and observation suggest that as an area approaches a threshold in response to disturbance, there is a concomitant change in the spatial arrangement of vegetation patches. This change is readily identifiable on fine spatial resolution aerial photography or satellite sensor imagery. We propose a classification method for identifying threshold-inducing change in vegetation pattern. To illustrate this method, we have applied an object-oriented, supervised classification to subsets of Quickbird imagery (70 cm ground resolution) over the Jornada basin in southern New Mexico. The imagery covers several land management regimes (private, public, federal) and provides spatial variation in ecosystem conditions. Imagery was first segmented to create fine and coarse resolution image objects. Fine resolution image objects are defined as having within-object spectral homogeneity at the scale of the shrub or single patch of grass or soil. Coarse resolution image objects are defined as containing spectral homogeneity at the scale of the vegetation stand. A classification tree was used to classify coarse resolution image objects to high risk of a threshold, low risk of a threshold, or post-threshold according to the content and spatial arrangement of shrub, grass and soil patches within them. Ground-based monitoring to detect localized threshold conditions across broad management areas is intractable so the use of remote sensing is essential to successful prevention of threshold development.

Steele, C. M.; Bestelmeyer, B. T.; Rango, A.; Smith, P. L.; Laliberte, A. S.

2007-12-01

278

Hydrogeochemical processes in the groundwater environment of Heihe River Basin, northwest China  

Microsoft Academic Search

The Heihe River Basin is a typical arid inland river basin for examining stress on groundwater resources in northwest China.\\u000a The basin is composed of large volumes of unconsolidated Quaternary sediments of widely differing grain size, and during the\\u000a past half century, rapid socio-economic development has created an increased demand for groundwater resources. Understanding\\u000a the hydrogeochemical processes of groundwater and

Zhu Gaofeng; Su Yonghong; Huang Chunlin; Feng Qi; Liu Zhiguang

2010-01-01

279

Agricultural and environmental changes after irrigation management transfer in the Develi Basin, Turkey  

Microsoft Academic Search

Develi Basin is a semi-arid basin in central Turkey where water sustains both irrigated agriculture and an internationally\\u000a important wetland, the Sultan Marshes. Agricultural and environmental changes in the Develi Basin have occurred since irrigation\\u000a management was transferred in 1994 from a state authority (DSI) to irrigation associations (Koval? and A?caa?ar IAs). In this\\u000a paper we evaluate the practices of

Filiz Dadaser-Celik; Patrick L. Brezonik; Heinz G. Stefan

2008-01-01

280

Distinctive channel geometry and riparian vegetation: A geomorphic classification for arid ephemeral streams  

NASA Astrophysics Data System (ADS)

Interactions between hydrology, channel form, and riparian vegetation along arid ephemeral streams are not thoroughly understood and current stream classifications do not adequately represent variability in channel geometry and associated riparian communities. Relatively infrequent hydrologic disturbances in dryland environments are responsible for creation and maintenance of channel form that supports riparian communities. To investigate the influence of channel characteristics on riparian vegetation in the arid southwestern United States, we develop a geomorphic classification for arid ephemeral streams based on the degree of confinement and the composition of confining material that provide constraints on available moisture. Our conceptual model includes five stream types: 1) bedrock channels entirely confined by exposed bedrock and devoid of persistent alluvium; 2) bedrock with alluvium channels at least partially confined by bedrock but containing enough alluvium to create bedforms that persist through time; 3) incised alluvium channels bound only by unconsolidated alluvial material into which they are incised; 4) braided washes that exhibit multi-thread, braided characteristics regardless of the composition of confining material; and 5) piedmont headwater 0-2nd order streams (Strahler) confined only by unconsolidated alluvium and which initiate as secondary channels on piedmont surfaces. Eighty-six study reaches representing the five stream types were surveyed on the U.S. Army Yuma Proving Ground in the Sonoran Desert of southwestern Arizona. Non-parametric multivariate analysis of variance (PERMANOVA) indicates significant differences between the five stream types with regards to channel geometry (i.e., stream gradient, width-to-depth ratio, the ratio between valley width and channel width (Wv/Wc), shear stress, and unit stream power) and riparian vegetation (i.e., presence and canopy coverage by species, canopy stratum, and life form). Discriminant analysis of the physical driving variables is being conducted to produce a model that predicts stream type and resulting riparian vegetation communities based on channel geometry. This model will be tested on a separate set of 15 study reaches surveyed on the Barry M. Goldwater Air Force Range in southern Arizona. The resulting classification will provide a basis for examining relationships between hydrology, channel and watershed characteristics, riparian vegetation and ecosystem sensitivity of ephemeral streams in arid regions of the American Southwest.

Sutfin, N.; Shaw, J. R.; Wohl, E. E.; Cooper, D.

2012-12-01

281

Sedimentation of the Triassic–Jurassic Adigrat Sandstone Formation, Blue Nile (Abay) Basin, Ethiopia  

Microsoft Academic Search

Exploration of oil and gas deposits in the Blue Nile Basin targeted the Adigrat Sandstone Formation as a reservoir objective. Conglomerates, gravely sandstones, coarse to medium-grained sandstones, very fine-grained cross-bedded sandstones, siltstones and mudstones of the Adigrat Sandstone Formation were deposited in semi-arid to arid climates. The North-western highlands are the main source for the sedimentation. The poorly-sorted, crudely-bedded conglomerates

A. Wolela

2008-01-01

282

Strategies for cooler cities? Ecophysiological responses of semi-arid street trees to storm water harvesting  

NASA Astrophysics Data System (ADS)

As the southwestern U.S. moves into an uncertain future in terms of water supply and climate, communities are seeking creative ways to harvest urban runoff. One such solution is to implement water-sensitive urban design features such as rain basins, which are designed to capture and facilitate infiltration of precipitation and storm water as it runs off impermeable surfaces like streets and sidewalks. Rain basins essentially act as temporary cisterns, allowing a given rain event to have a much larger impact in recharging soil water profiles. In this sense, even a 'small' rain may yield a more saturated soil profile and stimulate plant physiological activity well beyond plants that lack this additional moisture input. However, the impacts of rain basins on plant function remain unquantified. Therefore, the purpose of our research is to characterize the performance of native mesquite trees in basins relative to non-basin native mesquites. To answer our question, we randomly sampled basin and non-basin native mesquites in two different neighborhoods in Tucson, AZ, and characterized their response to precipitation events. We measured stomatal conductance, a proxy for transpiration, on the first and third days following rain events in 2013. Numerous environmental factors, such as photosynthetically available radiation (PAR), temperature, relative humidity, and soil moisture, were also measured in order to explore relationships with conductance. These measurements were conducted before and during monsoon season in order to determine the significance of water in basin performance, enabling us to better characterize plant response to medium (6 to 12 mm) rain events. Findings from this study indicate that basin and non-basin mesquites have similar pre-monsoon conductance rates, with a mean basin value of 70 +/-10 mmol/(m2*s) and a mean non-basin value of 57 +/-6 mmol/(m2*s) at peak conductance. In contrast, during the monsoon, basin mesquites showed significantly higher peak conductance rates (179 +/-22 mmol/(m2*s)) than non-basin trees (126 +/-9 mmol/(m2*s)). Perhaps more importantly, basin mesquite conductance remained elevated for an extended period of time into the afternoon as compared to non-basin mesquites. While this difference was negligible before the monsoon, it was significant during the monsoon. The day immediately after a medium rainfall event, non-basin mesquites shut down around 13:00, while basin mesquites never shut down completely before the end of the measurement period around 17:30. Soil moisture levels were elevated in the rain basins relative to the non-basin soils, suggesting that basins impact plant functioning through enhanced soil water availability. These preliminary results demonstrate that basins are an effective means of capturing water and irrigating plants. Here we have demonstrated how an appreciation of wildland plant ecophysiology can be applied to an urban setting in support of a suite of ecosystem services. Notably, there is a potential for enhanced urban heat island mitigation in semi-arid cities through the application of water-sensitive urban design features such as rain basins, due to their supporting a longer duration of latent heat flux cooling (i.e., transpiration) into the afternoon.

DeMets, C. M.; Pavao-zuckerman, M.; Barron-Gafford, G.

2013-12-01

283

Elementary and Secondary Education in Arid Lands.  

ERIC Educational Resources Information Center

The basic point to be considered in establishing a curriculum for elementary and secondary schools in the arid areas of the world is relevancy. Usually, the educational system of an area reflects the dominant culture of the political power in control. However, the educational system of the dominant culture might not be relevant to the people of…

Wilson, Herbert B.

284

Mountains and Arid Climates of Middle Latitudes  

Microsoft Academic Search

Simulations from a global climate model with and without orography have been used to investigate the role of mountains in maintaining extensive arid climates in middle latitudes of the Northern Hemisphere. Dry climates similar to those observed were simulated over central Asia and western interior North America in the experiment with mountains, whereas relatively moist climates were simulated in these

S. Manabe; A. J. Broccoli

1990-01-01

285

Unbalanced sediment budgets in the catchment-alluvial fan system of the Kuitun River (northern Tian Shan, China): Implications for mass-balance estimates, denudation and sedimentation rates in orogenic systems  

NASA Astrophysics Data System (ADS)

Mass balances are often used to calculate sediment fluxes in foreland basins and denudation rates in adjacent mountain ranges on intermediate to long timescales (from a few tens of thousand to a million years). Here, we study the simple Quaternary catchment-alluvial fan system of the Kuitun River, in northern Tian Shan, to discuss some ideas about sediment storage, release, and bypass in relatively short (100 km long) sediment routing systems. This study shows that the Kuitun catchment and piedmont areas clearly present evidence of a significant and temporary storage of sediments during the Pleistocene. These sediments were then excavated and delivered farther into the foreland basin during the Holocene. The difference between the volumes of materials released from the catchment and piedmont areas (5.5 ± 1.7 km3) and the volume stored in a contemporaneous fan downstream (2.6 ± 0.6 km3) indicates that the latter did not trap the whole sediment load transported by the river. The alluvial fan was bypassed by 27 to 78% of this load toward its distal alluvial plain. If this value is well estimated, it implies a major volumetric partitioning of the deposits between the fan and the alluvial plain, with a very high sedimentation rate in the fan (1.97 ± 0.52 mm·y- 1) and a much lower one downstream (0.11 ± 0.11 mm·y- 1). However, this volumetric partitioning might only occur during periods with a very specific hydrological regime such as the Holocene deglaciation. Eventually, the peculiar sediment storage and release pattern within the Kuitun catchment and piedmont areas during the Pleistocene and Holocene complicates the calculation of mean paleodenudation rates using either sediment budgets or in situ produced cosmogenic nuclides.

Jolivet, Marc; Barrier, Laurie; Dominguez, Stéphane; Guerit, Laure; Heilbronn, Gloria; Fu, Bihong

2014-06-01

286

Kinematic wave model for transient bed profiles in alluvial channels under nonequilibrium conditions  

E-print Network

deficiency) of sediment supply due to mostly flows during flash floods or floods resulting from dam break or dike failure. In such situations the sediment transport process occurs under nonequilibrium conditions, and extensive changes in alluvial river...

Tayfur, Gokmen; Singh, Vijay P.

2007-12-27

287

Natural arsenic contamination of Holocene alluvial aquifers by linked tectonic, weathering, and microbial processes  

E-print Network

Natural arsenic contamination of Holocene alluvial aquifers by linked tectonic, weathering tectonic, geochemical, and biologic processes lead to natural arsenic contamination of groundwater are commonly found a long distance from their ultimate source of arsenic, where chemical weathering of As

Fayek, Mostafa

288

Systematic oversteepening in longitudinal profiles of mixed bedrock-alluvial channels at tributary junctions : Appalachians, Virginia  

E-print Network

Certain mixed bedrock/alluvial channels located in the Valley and Ridge province of the Appalachians in Virginia were identified as having a pattern of systematic oversteepening of channel gradients at tributary junctions. ...

Windhorst, Leah M. (Leah Marie), 1981-

2004-01-01

289

INFILTRATION OF ATRAZINE AND METABOLOTES FROM A STREAM TO AN ALLUVIAL AQUIFER  

EPA Science Inventory

The infiltration of atrazine, deethylatrazine, and deisopropylatrazine from Walnut Creek, a tributary stream, to the alluvial valley aquifer along the South Skunk River in central Iowa occurred where the stream transects the river's flood plain. A preliminary estimate indicated t...

290

Performance study on basin type double slope solar still with different wick materials and minimum mass of water  

Microsoft Academic Search

Solar still is one of the best solutions to solve water problem in remote arid areas. This device is not popular because of its lower productivity. One of the methods to increase the productivity is by decrease the volumetric heat capacity of the basin. A layer of water with wick material in the basin will increase the evaporation area and

K. Kalidasa Murugavel; K. Srithar

2011-01-01

291

Interactions Between Tectonics, Sedimentation and Climate in the Intramontane Bólson de Fiambalá Basin: Southern Puna Plateau (NW Argentina)  

NASA Astrophysics Data System (ADS)

The Puna Plateau is part of the larger Puna-Altiplano region which is the second largest Plateau on Earth. The Puna is characterized by high mean elevation at ~3700m with peaks above 6000m, internal drainage and hyper-aridity. The uplift of this important region must have influenced climate patterns, erosion, sediment- dispersal patterns and the evolution of the tectonic stress field in adjacent regions. In order to better understand the interactions between these important processes we have investigated the intramontane Bolsón de Fiambalá Basin (BF) at about 27 \\deg45'S, 67 \\deg45'W. The BF is located in the structural transition between the high-angle reverse fault bounded Sierra Pampeanas structural province and the southern margin of the intra-Andean Puna. The investigation of clastic sediments deposited in intramontane basins straddling the eastern and southern margin of the Puna provides fundamental information on timing and spatial patterns of plateau evolution in the orogen interior. Our sedimentologic and structural data show that sedimentation in the BF started under E-W contraction in late Miocene time in an climate characterized by an ephemeral fluvial system sourced in the west. Subsidence analysis suggests that accommodation space was provided by tectonic loading due to the eastward advance of thrust sheets. Sedimentation with more humid intervals continued during the late Miocene-Pliocene associated with further thrust-front advance and the influence of proximal western sediment sources and the formation of an established fluvial system. Probably by late Pliocene time the BF became overfilled and thick, coarse alluvial fan conglomerates sourced in the W and NE were deposited. Our analysis suggests that subsidence in this last period was mainly due to sediment loading, while tectonic loading by western thrusts apparently played a minor role. This interpretation is in line with provenance data which suggest an enlargement of the drainage system with the contribution of Puna-related rocks to the basin fill, suggesting an uplift pulse in the plateau realm. These events appear to have been roughly coeval with a change in the shortening direction from E-W to WNW-ESE to a neotectonic ENE-WSW orientation, also observed in other parts of the Argentine Andes farther north. Our new observations in the BF thus provide important information on the last phase of plateau uplift at the transition between the late Pliocene and early Pleistocene.

Carrapa, B.; Barbieri, C.; Hauer, J.; Sosa Gomez, J.; Strecker, M.; Schoenbohm, L.

2004-12-01

292

Rapid migration of heavy metals and 137 Cs in alluvial sediments, Upper Odra River valley, Poland  

Microsoft Academic Search

The studies presented explore post-depositional changes of zinc, cadmium, lead, manganese and 137Cs distribution in alluvial sediments accumulated in the upper Odra River valley in southern Poland. The rate of these changes\\u000a was estimated by comparing metal and 137Cs distributions in four vertical alluvial profiles with a history of river pollution and sediment deposition. The untypical\\u000a 137Cs distribution with peaks

Dariusz Ciszewski; Agnieszka Czajka; Sylwia B?a?ej

2008-01-01

293

An engineering geologic impact analysis of hydraulic dredging for lignite in Texas alluvial valleys  

E-print Network

AN ENGINEERING GEOLOGIC IMPACT ANALYSIS OF HYDRAULIC DREDGING FOR LIGNITE IN TEXAS ALLUVIAL VALLEYS A Thesis by ERICH DONALD LUIS NOLAN Submitted to the Graduate College of Texas ASM University in partial fulfillment of the reguirement... for the degree of NASTER OF SCIENCE Nay 1985 Najor Subject: Geology AN ENGINEERING GEOLOGIC IMPACT ANALYSIS OF HYDRAULIC DREDGING FOR LIGNITE IN TEXAS ALLUVIAL VALLEYS A Thesis by ERICH DONALD LUIS NOLAN Approved as to style and content by: C rz top er...

Nolan, Erich Donald Luis

2012-06-07

294

Eocene exhumation and basin development in the Puna of northwestern Argentina  

NASA Astrophysics Data System (ADS)

The Puna is part of the larger Puna-Altiplano Plateau (also known as the Central Andean Plateau), characterized by high elevation, low relief, and aridity, located in the central Andes of Bolivia and Argentina. Tertiary sedimentary rocks preserved within the Puna contain a unique archive of information regarding the paleogeography, depositional environments, and timing of sediment source exhumation during the early stages of Andean mountain building. The Eocene Geste Formation in the Salar de Pastos Grandes area (within the central Puna of northwestern Argentina) consists of deposits that are the result of confined to unconfined flows in a sandy to gravelly, braided fluvial system and alluvial fans proximal to the source terrane. Paleocurrent data document an overall eastward flow direction. Up-section coarsening of the Geste Formation suggests that topographic relief in the source area increased through time, possibly owing to enhanced tectonic activity and source terrane unroofing. Sandstone petrography and conglomerate clast-count data document quartzose and phyllitic compositions typical of Ordovician rocks preserved just west of the Salar de Pastos Grandes area. Paleocene-Eocene detrital apatite fission track age populations (P1: ˜35-52 Ma; P2: ˜52-65 Ma) of the Geste Formation and their consistent trends up-section suggest moderate to rapid (˜0.4 mm/a to >1 mm/a) exhumation of western sediment sources during the early to mid-Tertiary stages of Andean mountain building. Sedimentation rates increase up-section from ˜0.1 mm/a to 1 mm/a. Our data, when combined with other structural, stratigraphic and seismic evidence from surrounding regions, suggest that the Geste Formation was deposited in response to crustal shortening and resulting erosion and sedimentation, which started as early as Cretaceous in the Chilean Cordillera de Domeyko and in the Salar de Pastos Grandes area by Eocene time. The Geste Formation could be interpreted either as a local wedge-top accumulation on the eastward propagating central Andean orogenic wedge, or as a local intermontane basin. The similarities between wedge-top deposits preserved in Bolivia and Eocene deposits in northwestern Argentina, south of ˜25°S, lead us to favor the wedge-top scenario for the Geste Formation. If correct, this implies that the deformation front of the Andean orogenic wedge incorporated both thin- and thick-skinned structures as it migrated, possibly unsteadily, from the Cordillera de Domeyko during the Cretaceous-Paleocene to areas within the Puna and Eastern Cordillera by mid-late Eocene time. Contemporaneously, a regional-scale foreland basin system developed over an along-strike distance of at least 650 km.

Carrapa, B.; Decelles, P. G.

2008-02-01

295

The influence of fires on the properties of forest soils in the Amur River basin (the Norskii Reserve)  

Microsoft Academic Search

The influence of forest fires on the properties of taiga brown, gley taiga brown, and alluvial bog soils widespread in the area of the Norskii Reserve (the Amur River basin) was studied. During several years after the fire, the humus content increased, especially in the soils subjected to fires of high intensity. In the soils of steep slopes, the humus

A. S. Tsibart; A. N. Gennadiev

2008-01-01

296

Sedimentation and depositional environments of the Barremian-Cenomanian Debre Libanose Sandstone, Blue Nile (Abay) Basin, Ethiopia  

Microsoft Academic Search

Exploration of oil and gas deposits in the Blue Nile Basin targeted the Debre Libanose Sandstone as a reservoir objective. The unit was deposited in broad alluvial plains, and shows some elements of the Platte type braided river sedimentation in the lower and middle succession. The braided river sedimentation is dominated by single storey and multistorey amalgamated sandstone bodies, and

A. Wolela

2009-01-01

297

Ecological effects of water retention in the River Rhine valley: a review assisting future retention basin classification  

Microsoft Academic Search

This review paper summarizes the ecological effects of the use of floodplains and flood retention basins to control river flow in the River Rhine (Rhein) valley. Early River Rhine regulation strategies including channel straightening are assessed. The subsequent disappearance of alluvial hardwood forests has been highlighted as the major disadvantage. The response of trees to more recent strategies such as

M. Scholz

2007-01-01

298

Diazotrophy in Alluvial Meadows of Subarctic River Systems  

PubMed Central

There is currently limited understanding of the contribution of biological N2 fixation (diazotrophy) to the N budget of large river systems. This natural source of N in boreal river systems may partially explain the sustained productivity of river floodplains in Northern Europe where winter fodder was harvested for centuries without fertilizer amendments. In much of the world, anthropogenic pollution and river regulation have nearly eliminated opportunities to study natural processes that shaped early nutrient dynamics of large river systems; however, pristine conditions in northern Fennoscandia allow for the retrospective evaluation of key biochemical processes of historical significance. We investigated biological N2 fixation (diazotrophy) as a potential source of nitrogen fertility at 71 independent floodplain sites along 10 rivers and conducted seasonal and intensive analyses at a subset of these sites. Biological N2 fixation occurred in all floodplains, averaged 24.5 kg N ha?1 yr?1 and was down regulated from over 60 kg N ha?1 yr?1 to 0 kg N ha?1 yr?1 by river N pollution. A diversity of N2-fixing cyanobacteria was found to colonize surface detritus in the floodplains. The data provide evidence for N2 fixation to be a fundamental source of new N that may have sustained fertility at alluvial sites along subarctic rivers. Such data may have implications for the interpretation of ancient agricultural development and the design of contemporary low-input agroecosystems. PMID:24223119

DeLuca, Thomas H.; Zackrisson, Olle; Bergman, Ingela; Diez, Beatriz; Bergman, Birgitta

2013-01-01

299

Age-dating volcanic and alluvial surfaces with multipolarization data  

NASA Technical Reports Server (NTRS)

A false-color multipolarization version of one of the images of Owens Valley area acquired by the JPL Synthetic Aperture Radar (SAR) is given. A geologic map of the alluvial fans there (Gillespie, 1982) is also given for comparison. In general, brightness in the multipolarization images can be seen to be inversely proportional to the age of the surfaces. A more detailed investigation of the relationship between backscatter and age of the surfaces was undertaken with calibrated aircraft SAR data. The quantitative relationship between backscatter coefficient and age for the three polarizations is shown. The straight lines connecting the measured data points imply a steady-state process, although the process or processes leading to this relationship may have operated at rates that varied with climate fluctuations, such as the glacial ages. It is expected that the relationship between radar brightness and age is a consistent one, and that with the wider availability of calibrated radar backscatter data, these relationships can be less well-known areas. The effect of variable such as past climate fluctuations, tectonic disturbance, and rock type must be understood before extension beyond the Mojave Desert region can be attempted.

Farr, T. G.

1985-01-01

300

Floodplain biogeochemical mosaics: A multidimensional view of alluvial soils  

NASA Astrophysics Data System (ADS)

alluvial floodplains of large rivers are exceptionally productive and dynamic ecosystems, characterized by a complex mosaic of vegetation at different successional stages overlying soils sorted by historic floods. Natural floodplains are widely credited with efficiently removing nitrogen from surface waters and accumulating carbon in biomass, yet very little floodplain research has examined carbon and nitrogen cycling below surficial soils. We evaluated the extent to which vegetation cover could be used to predict subsurface carbon and nitrogen dynamics and to estimate whole-floodplain carbon storage and denitrification rates. We dug soil pits under three dominant vegetation communities on a gravel-bedded floodplain in northwest Montana to the depth of the permanent water table (1-3 m). We compared depth profiles of total and dissolved carbon (C) and nitrogen (N), denitrification potentials (DEAs), organic particulates, moisture, and pH across vegetation types. Near-surface soils (0-10 cm) of forests had larger C and N pools and DEAs than grasslands or gravel bars, but such vegetation effects dissipated within the upper ~50 cm of soil. At depth, spatial heterogeneity in carbon and nitrogen pools and fluxes depended instead on soil texture, and relatively high rates of DEA and carbon storage were measured in zones of buried organic debris. Although C storage and denitrification potential are generally low in subsurface soils, these deep soils might nonetheless contribute substantially to whole-floodplain C storage and denitrification because of their large volume, high hydrologic connectivity, and heterogeneous biogeochemistry.

Appling, Alison P.; Bernhardt, Emily S.; Stanford, Jack A.

2014-08-01

301

Proterozoic silcretes and arid climate lithogenesis in the northwest Canadian shield  

SciTech Connect

Siliciclastic sedimentary rocks at the base of the 1.7 Ga Hornby Bay Group record sedimentation in an intracratonic basin developed following terminal tectonic activity in the underlying Wopmay Orogen. Clastic and pedogenic sediments at the basal unconformity contain abundant evidence of penecontemporaneous silica cementation and share many aspects of their petrography and general geologic setting with Cenozoic arid silcretes of the Kalahari region (S. Africa) and are likewise inferred to have formed in an arid paleoclimate. Sedimentation along the unconformity was dominated by spallation and formation of silica-cemented rock fan pediments that mantle basement paleohighs. Ephemeral lake sediments are locally present and consist of silica-cemented sheetwash and aeolian sandstone, silicified mudstone and evaporitic/pisolitic chert. Early pedogenic cements consist of isopachous fibrous-prismatic chalcedony that was followed by generation of clotted to laminoid fenestral cavities infilled first by massive cryptocrystalline silica and then crusts of zoned spherular megaquartz and both length-fast and length-slow chalcedony. The association of various silica types, evaporite pseudomorphs and inferred arid paleoclimate are consistent with complex history of modification of alkaline groundwater by precipitation and evaporitive concentration. The results of this study demonstrate the significance of early pedogenetic/diagenetic events in paleosols and underscores the necessity for careful petrographic analysis before approaching the vagaries of paleosol chemistry.

Ross, G.M.

1985-01-01

302

Nutrient uptake as a contributing explanation for deep rooting in arid and semi-arid ecosystems.  

PubMed

Explanations for the occurrence of deep-rooted plants in arid and semi-arid ecosystems have traditionally emphasized the uptake of relatively deep soil water. However, recent hydrologic data from arid systems show that soil water potentials at depth fluctuate little over long time periods, suggesting this water may be rarely utilized or replenished. In this study, we examine the distributions of root biomass, soil moisture and nutrient contents to 10-m depths at five semi-arid and arid sites across southwestern USA. We couple these depth distributions with strontium (Sr) isotope data that show deep (>1 m) nutrient uptake is prevalent at four of the five sites. At all of the sites, the highest abundance of one or more of the measured nutrients occurred deep within the soil profile, particularly for P, Ca2+ and Mg2+. Phosphate contents were greater at depth than in the top meter of soil at three of five sites. At Jornada, for example, the 2-3 m depth increment had twice the extractable P as the top meter of soil, despite the highest concentrations of P occurring at the surface. The prevalence of such deep resource pools, and our evidence for cation uptake from them, suggest nutrient uptake as a complementary explanation for the occurrence of deep-rooted plants in arid and semi-arid systems. We propose that hydraulic redistribution of shallow surface water to deep soil layers by roots may be the mechanism through which deep soil nutrients are mobilized and taken up by plants. PMID:15322902

McCulley, R L; Jobbágy, E G; Pockman, W T; Jackson, R B

2004-12-01

303

Late Holocene upper bounds of flood magnitudes and twentieth century large floods in the ungauged, hyperarid alluvial Nahal Arava, Israel  

NASA Astrophysics Data System (ADS)

The impact of large twentieth century floods on the riparian vegetation and channel morphology of the relatively wide anabranching and braided Nahal Arava, southern Israel, was documented as part of developing tools to (a) identify recent large floods, (b) determine these flood's respective magnitudes in alluvial ungauged streams, and (c) determine long-term upper bounds to flood stages and magnitudes. Along most of its course Nahal Paran, a major tributary that impacts the morphology, floods and sediments of Nahal Arava at the study reach, is a coarse-gravel, braided ephemeral stream. Downstream of the Arava-Paran confluence, aeolian and fluvial sand delivered from eastern Arava valley alters the channel morphology. The sand has accreted up to 2.5 m above the distinct current channels, facilitating the recording of large floods. This sand enhances the establishment of denser riparian vegetation (mainly Tamarix nilotica and Haloxylon persicum) that interacts with floods and affects stream morphology. A temporal association was found between specific floods recorded upstream and tree-ring ages of re-growth of flood-damaged tamarix trees ('Sigafoos trees') in the past 30 years. This association can be utilized for developing a twentieth century flood chronology in hyperarid ungauged basins in the region. The minimum magnitude of the largest flood that covered the entire channel width, estimated from flood deposits, is approximately 1700-1800 m 3s - 1 . This is a larger magnitude than the largest gauged flood of 1150 m 3s - 1 that occurred in 1970 about 30 km upstream in Nahal Paran. Our estimation agrees with flood magnitude estimated from the regional envelope curve of the largest floods. Based on Holocene alluvial stratigraphy and OSL dating in the study reach we also conclude that flood stages did not reach the late Holocene (˜ 2.2 ka) surface and therefore we estimate a non-exceedance upper bound of ˜ 2000 m 3s - 1 flood magnitudes for Nahal Arava during that interval. This study indicates that in unfavorable areas the combination of hydrology, fluvial morphology and botanic evidence can increase our understanding of ungauged basins and give information crucial for hydrology planning.

Jacoby, Yael; Grodek, Tamir; Enzel, Yehouda; Porat, Naomi; McDonald, Eric V.; Dahan, Ofer

2008-03-01

304

Landscape ecological risk assessment study in arid land  

NASA Astrophysics Data System (ADS)

The ecosystem risk assessment is an essential decision making system for predicting the reconstruction and recovery of a damaged ecosystem after intensive mankind activities. The sustainability of environment and resources of the lake ecosystem in arid districts have been paid close attention to by international communities as well as numerous experts and scholars. The ecological risk assessment offered a scientific foundation for making the decision and execution of ecological risk management. Bosten Lake, the largest inland freshwater lake in China, is the main water source of the industrial and agricultural production as well as the local residence in Yanqi basin, Kuara city and Yuri County in the southern Xinjiang. Bosten Lake also provides a direct water source for emergency transportation in the Lower Reaches of Tarim River. However, with the intensive utilizations of water and soil resources, the environmental condition in the Bosten Lake has become more and more serious. In this study, the theory and method of landscape ecological risk assessment has been practiced using 3S technologies combined with the frontier theory of landscape ecology. Defining the mainly risk resource including flood, drought, water pollution and rich nutrition of water has been evaluated based on the ecosystem risk assessment system. The main process includes five stages: regional natural resources analysis, risk receptor selection, risk sources evaluation, exposure and hazard analysis, and integrated risk assessment. Based on the risk assessment results, the environmental risk management countermeasure has been determined.

Gong, Lu; Amut, Aniwaer; Shi, Qingdong; Wang, Gary Z.

2007-09-01

305

Lower Palaeozoic Alluvial Systems: The Sedimentological Impact of Evolving Vegetation in Terrestrial Environments  

NASA Astrophysics Data System (ADS)

In present-day alluvial environments, the impact of vegetation on sedimentological processes and deposits is well known. A vegetated catchment may decrease sediment yield, sediment erodability, Hortonian overland flow, aeolian winnowing of fines, the proportion of sediment transported as bedload, may increase bank stability, infiltration into substrates, bed roughness, and can promote the production of chemically-weathered clays and soils and the adoption of a meandering style. It is generally understood that, prior to the evolution of terrestrial vegetation during the Lower Palaeozoic, ancient alluvial systems were markedly different from modern systems, with many systems adopting a "sheet-braided" style. This understanding has previously informed the interpretations of many Precambrian pre-vegetation alluvial successions, but there has been relatively little work regarding Lower Palaeozoic alluvial successions that existed during the active terrestrialization of plants. In this study, a comprehensive review of 141 Cambrian to Devonian alluvial successions documented in published literature was combined with original field data from 20 alluvial successions from across Europe and North America, in order to identify changes in the sedimentary style of alluvial strata while vegetation was evolving and colonizing alluvial environments. This approach has established clear trends indicating an increase in mudrocks and sandstone maturity and a decrease in overall sand grain size through the Lower Palaeozoic, suggesting that primitive vegetation cover was able to promote the production and preservation of muds and increase the residence time of sand-grade sediment (and thus sediment reworking) in alluvial systems. It has also enabled the first stratigraphic occurrence of certain vegetation-dependent sedimentary features to be pinpointed and tied directly to the onset of specific evolutionary adaptations recorded in the palaeobotanical fossil record. As such, the first markedly heterolithic alluvial sequences can be shown to first appear at the same time as the most primitive terrestrial vegetation in the Lower Ordovician, whilst pedogenic calcite first appears in the rock record at the same time as vascular plants in the Lower Silurian. Vertisols, coal, and certain indicators of meandering fluvial style (lateral accretion surfaces) only appear after the development of plant arborescence and deep rooting in the Devonian.

Davies, N. S.; Gibling, M. R.

2009-04-01

306

Cambrian to Devonian evolution of alluvial systems: The sedimentological impact of the earliest land plants  

NASA Astrophysics Data System (ADS)

In present-day alluvial environments, the impact of vegetation on sedimentological processes and deposits is well known. A vegetated catchment may decrease sediment yield, sediment erodibility, Hortonian overland flow, aeolian winnowing of fines, the proportion of sediment transported as bedload, and may increase bank stability, infiltration into substrates, and bed roughness. Vegetation also promotes the production of chemically-weathered clays and soils and the adoption of a meandering style. It is generally understood that, prior to the evolution of terrestrial vegetation during the Early Palaeozoic, ancient alluvial systems were markedly different from modern systems, with many systems adopting a "sheet-braided" style. This understanding has previously informed the interpretations of many Precambrian pre-vegetation alluvial successions, but there has been relatively little work regarding Early Palaeozoic alluvial successions laid down prior to and during the initial colonization of the Earth's surface by plants. A comprehensive review of 144 Cambrian to Devonian alluvial successions documented in published literature was combined with original field data from 34 alluvial successions across Europe and North America. The study was designed to identify changes in alluvial style during the period that vegetation was evolving and first colonizing alluvial environments. An increase in mudrock proportion and sandstone maturity is apparent, along with a decrease in overall sand grain size through the Early Palaeozoic. These trends suggest that primitive vegetation cover promoted the production and preservation of muds from the mid Ordovician onwards and increased the residence time of sand-grade sediment in alluvial systems. The compilation also enables the first stratigraphic occurrence of certain vegetation-dependent sedimentary features to be pinpointed and related to the evolution of specific palaeobotanical adaptations. The first markedly heterolithic alluvial sequences appeared at about the same time as the most primitive terrestrial vegetation in the Ordovician, and prolific pedogenic calcite, charcoal and bioturbated floodplain fines first appeared in the rock record at about the same time as vascular-plant macrofossils became abundant in the late Silurian. Lateral accretion sets in channel deposits appeared near the Silurian-Devonian boundary, at or shortly before the appearance of underground rooting systems, and become progressively more abundant in the record during the Devonian, implying a major expansion of meandering rivers as rooted plants stabilized river banks. Coals become abundant after the development of plant arborescence. The analysis suggests that the evolution of embryophytes had a profound effect on fluvial processes and deposits, and this period of landscape evolution must be considered amongst the most significant environmental and geomorphological changes in Earth history, with profound consequences for all aspects of the Earth system.

Davies, Neil S.; Gibling, Martin R.

2010-02-01

307

Geohydrologic framework of the Roswell ground-water basin, Chaves and Eddy Counties, New Mexico  

USGS Publications Warehouse

This report describes the geohydrology of the Roswell ground-water basin and shows the long-term hydrostatic-head changes in the aquifers. The Roswell ground-water basin consists of a carbonate artesian aquifer overlain by a leaky confining bed, which, in turn is overlain by an alluvial water-table aquifer. The water-table aquifer is hydraulically connected to the Pecos River. Ground-water pumpage from about 1,500 wells in the basin was about 378,000 acre-feet in 1978. Irrigation use on about 122,000 acres accounted for 95 percent of that pumpage.

Welder, G. E.

1983-01-01

308

Guatemalan forest synthesis after Pleistocene aridity  

PubMed Central

Sediments from two lakes in the Peten Department, Guatemala, provide palynological evidence from Central America of late Pleistocene aridity and subsequent synthesis of mesic forests. Late Glacial vegetation consisted of marsh, savanna, and juniper scrub. An early Holocene temperate forest preceded a mesic tropical forest with Brosimum (ramon). Thus “primeval” rain forests of Guatemala are no older than 10,000 to 11,000 years and are considerably younger in the Peten due to Mayan disturbances. Among dated Neotropical sites, the Peten has the most mesic vegetation yet shown to have supplanted xeric vegetation present during the Pleistocene. The arid late Glacial-humid early Holocene transition appears to have been pantropical in the lowlands. The Peten was not a Pleistocene refugium for mesophytic taxa, as has been suggested. Thus genesis of extant rain forests in northern Central America and southern Mexico remains unexplained. Images PMID:16593498

Leyden, Barbara W.

1984-01-01

309

VOCs in Arid soils: Technology summary  

SciTech Connect

The Volatile Organic Compounds In Arid Soils Integrated Demonstration (VOC-Arid ID) focuses on technologies to clean up volatile organic compounds and associated contaminants in soil and groundwater at arid sites. The initial host site is the 200 West Area at DOE`s Hanford site in southeastern Washington state. The primary VOC contaminant is carbon tetrachloride, in association with heavy metals and radionuclides. An estimated 580--920 metric tons of carbon tetrachloride were disposed of between 1955 and 1973, resulting in extensive soil and groundwater contamination. The VOC-Arid ID schedule has been divided into three phases of implementation. The phased approach provides for: rapid transfer of technologies to the Environmental Restoration (EM-40) programs once demonstrated; logical progression in the complexity of demonstrations based on improved understanding of the VOC problem; and leveraging of the host site EM-40 activities to reduce the overall cost of the demonstrations. During FY92 and FY93, the primary technology demonstrations within the ID were leveraged with an ongoing expedited response action at the Hanford 200 West Area, which is directed at vapor extraction of VOCs from the vadose (unsaturated) zone. Demonstration efforts are underway in the areas of subsurface characterization including: drilling and access improvements, off-gas and borehole monitoring of vadose zone VOC concentrations to aid in soil vapor extraction performance evaluation, and treatment of VOC-contaminated off-gas. These current demonstration efforts constitute Phase 1 of the ID and, because of the ongoing vadose zone ERA, can result in immediate transfer of successful technologies to EM-40.

Not Available

1994-02-01

310

Geotechnical Parameters of Alluvial Soils from in-situ Tests  

NASA Astrophysics Data System (ADS)

The article concentrates on the identification of geotechnical parameters of alluvial soil represented by silts found near Poznan and Elblag. Strength and deformation parameters of the subsoil tested were identified by the CPTU (static penetration) and SDMT (dilatometric) methods, as well as by the vane test (VT). Geotechnical parameters of the subsoil were analysed with a view to using the soil as an earth construction material and as a foundation for buildings constructed on the grounds tested. The article includes an analysis of the overconsolidation process of the soil tested and a formula for the identification of the overconsolidation ratio OCR. Equation 9 reflects the relation between the undrained shear strength and plasticity of the silts analyzed and the OCR value. The analysis resulted in the determination of the Nkt coefficient, which might be used to identify the undrained shear strength of both sediments tested. On the basis of a detailed analysis of changes in terms of the constrained oedometric modulus M0, the relations between the said modulus, the liquidity index and the OCR value were identified. Mayne's formula (1995) was used to determine the M0 modulus from the CPTU test. The usefullness of the sediments found near Poznan as an earth construction material was analysed after their structure had been destroyed and compacted with a Proctor apparatus. In cases of samples characterised by different water content and soil particle density, the analysis of changes in terms of cohesion and the internal friction angle proved that these parameters are influenced by the soil phase composition (Fig. 18 and 19). On the basis of the tests, it was concluded that the most desirable shear strength parameters are achieved when the silt is compacted below the optimum water content.

M?ynarek, Zbigniew; Stefaniak, Katarzyna; Wierzbicki, Jedrzej

2012-10-01

311

Fluvial transport and surface enrichment of arsenic in semi-arid mining regions: examples from the Mojave Desert, California.  

PubMed

As a result of extensive gold and silver mining in the Mojave Desert, southern California, mine wastes and tailings containing highly elevated arsenic (As) concentrations remain exposed at a number of former mining sites. Decades of weathering and erosion have contributed to the mobilization of As-enriched tailings, which now contaminate surrounding communities. Fluvial transport plays an intermittent yet important and relatively undocumented role in the migration and dispersal of As-contaminated mine wastes in semi-arid climates. Assessing the contribution of fluvial systems to tailings mobilization is critical in order to assess the distribution and long-term exposure potential of tailings in a mining-impacted environment. Extensive sampling, chemical analysis, and geospatial mapping of dry streambed (wash) sediments, tailings piles, alluvial fans, and rainwater runoff at multiple mine sites have aided the development of a conceptual model to explain the fluvial migration of mine wastes in semi-arid climates. Intense and episodic precipitation events mobilize mine wastes downstream and downslope as a series of discrete pulses, causing dispersion both down and lateral to washes with exponential decay behavior as distance from the source increases. Accordingly a quantitative model of arsenic concentrations in wash sediments, represented as a series of overlapping exponential power-law decay curves, results in the acceptable reproducibility of observed arsenic concentration patterns. Such a model can be transferable to other abandoned mine lands as a predictive tool for monitoring the fate and transport of arsenic and related contaminants in similar settings. Effective remediation of contaminated mine wastes in a semi-arid environment requires addressing concurrent changes in the amounts of potential tailings released through fluvial processes and the transport capacity of a wash. PMID:22718027

Kim, Christopher S; Stack, David H; Rytuba, James J

2012-07-01

312

Habitat Use, Movements, and Survival of Radio-Marked Female Mallards in the Lower Mississippi Alluvial Valley.  

E-print Network

??Mallard (Anas platyrhynhcos) populations in the Lower Mississippi Alluvial Valley (LMAV) historically averaged 1.6 million and represented the largest concentrations of wintering mallards in North… (more)

Davis, Bruce Edward

2007-01-01

313

Anthropic Modification of The Alluvial Plain and Flood Control In Some Marchean Rivers (central Italy).  

NASA Astrophysics Data System (ADS)

The fluvial axis of the marchean rivers display an essentially sinuate character, whereas in its terminal portion, where it runs through a wide valley, it assumes an anastomosed form. In the initial portion, where it runs inside the Umbro-Marchean calcareous ridge, the regime is prevalently stream like, while in the arenaceous and clayey hilly belt, it follows a more regular trend. In the middle-lower portion, and especially in summer, the hydrological regime is significantly influenced by the water drawn off for hydroelectric and irrigation purposes. The particular hydrographic and orographic setting of the study territory and the considerable amount of anthropic activity, both in the past and present, are responsible for the frequent and disastrous flooding and flash flooding phenomena that, during intense rainfall, affected vast areas of the middle-terminal portion of the alluvial plain. An analysis of the flooding events of the last years has in fact led to the observation that flooding and flash flooding phenomena, and the damage deriving from them, are connected especially with mistaken management of the territory and subordinately with abundant rainfalls in a short span of time. This includes the following factors: insufficient, or complete absence of works for maintaining natural levees and river beds; the obstruction of watercourses due to building with no respect for adequate hydraulic criteria; an excessive narrowing or straightening of the main river axis, above all in those portions near the mouth; runoff difficulties in the works connecting the main hydrographic network with the secondary one; insufficient disposal capacity or efficiency of the rain water outlet network; insufficient measures, or a lack of planning of measures and/or works for emergency protection systems; widespread situations of hydrogeological accident and slope instability, accentuated by the progressive abandoning of agriculture and repeated occurrence of forest fires. In particular, after the atmospheric events of the April, 1992, November 1998 and September 2000, which caused vast damages, it could be shown that the causes determining the flash flooding, as well as the occurrence of floods with return times of less than 20 years (flow rate of the order of 120 m3/sec) and which are increasing in the last decade, were attributable to four main causes: · deviations and artificial banks along the lower valley, dating from 1400 to 1500, for land reclamation and agriculture; · 15th century alterations and destruction due to anthropic settlements and more extensive agricultural cultivation; · beginning from the year 1900, the building of transversal works to deviate the water for hydroelectric and agricultural purposes with a hydraulic profile rate incompatible with that of the existent hydraulic defenses such as to cause flash floods due to breaking of the banks; · underestimation in measuring the fluvial discharge due to indiscriminate and strong exploitations of the aquifers for agriculture during arid periods.

Farabollini, P.; Materazzi, M.

314

Environmental significance of vesicular sediment structure in arid regions  

NASA Astrophysics Data System (ADS)

Vesicular structure is a frequent and widely spread phenomenon in surficial fine-grained sediments in arid environments. It typically affects the upper few millimetres to decimetres of sediment and consists of isolated, spherical to ovoid pores, some 100 to 1000 micrometres in diameter, which give the sediment a foamy appearance. The vesicular layer has, together with an often genetically associated stone pavement cover, major control functions for dust trapping as well as dust mobilisation, water infiltration, soil moisture and surface runoff, as well as ecological site characteristics. Accordingly, there are numerous but often contradictory hypotheses about vesicular structure formation. Most of them are based on individual experiments with settings that were never consistent and overarching but rather focused on one sediment or environmental variable and its relative influence on vesicle formation. We present highlights of extensive laboratory experiments where physical and chemical sediment properties as well as environmental variables such as wetting technique, wetting amount, surface cover type or drying temperature were changed systematically over the entire range of published characteristics of vesicular layers. A series of measures of vesicle features, derived from digitised sediment sections, forms the base for quantitative sample comparison. Furthermore, the experimental results are related to natural analogues from severe regions throughout a climatic gradient from the hyper-arid part of Baja California, Mexico, to the sub-humid southern Sevier Basin, USA. Based on the results, the plausibility of published vesicle formation hypotheses is discussed and a genetic model is formulated. Vesicles are no transient feature but rather evolve exponentially and become stabilised. They form due to surface puddling and a wetting front which advances downward, thereby elevating the gas pressure within the sediment matrix. Translocation of clay and calcium carbonate support stabilisation. An increasing sand content leads to larger and rounder vesicles, whereas calcium carbonate content has the opposite effect. The amount of dissolved ions does not considerably influence vesicle formation. Under a clast cover vesicles were not formed at all, which has consequences for the published genetic coupling of stone pavement and vesicular layer. Vesicular structures can be connected to environmental parameters which allows one to use fossilised formations as palaeo-environment proxy in sediment archives.

Dietze, M.; Kleber, A.

2012-04-01

315

Identification of rock weathering and environmental control in arid catchments (northern Xinjiang) of Central Asia  

NASA Astrophysics Data System (ADS)

Chemical weathering is an integral part of the earth surface processes, whose spatial patterns and controlling factors on continental scale are still not fully understood. Highlands of the Asian continent have been shown having some of the highest observed rates of chemical weathering yet reported. However, the paucity of river gauge data in many of these terrains has limited determination of chemical weathering budget in a continental scale. A dataset of three large watersheds throughout northern Xinjiang in Central Asia is used to empirically identify chemical weathering regimes and interpret the underlying controlling factors. Detailed analysis of major ion ratios and a forward model of mass budget procedure are presented to distinguish the relative significances and contributions of silicate, carbonate weathering and evaporite dissolution. The analytical results show that carbonic acid is the most important weathering agent to the studied watersheds. Silicate weathering contributes, on average, ˜17.8% (molar basis) of total cations on a basin wide scale with an order of Zhungarer > Erlqis > Yili, indicating that silicate weathering, however, does not seem to be intense in the study basins. Evaporite dissolution, carbonate weathering and precipitation input contribute 43.6%, 29.7% and 8.9% of the total dissolved cations on average for the whole catchment, respectively. The three main morphological and hydrological units are reflected in water chemistry. Rivers from the montane areas (recharge area) of the three watersheds are very dilute, dominated by carbonate and silicate weathering, whereas the rivers of piedmont areas as well as the rivers of the sedimentary platform (runoff area) are dominated by carbonate weathering, and rivers of desert plain in the central Zhungarer basin (discharge area) are dominated by evaporite dissolution and are SO4 rich. This spatial pattern indicates that, beside lithology, runoff conditions have significant role on the regional chemical weathering regimes. Chemical weathering processes in the areas appear to be significantly climate controlled, displaying a tight correlation with runoff and aridity. Carbonate weathering are mostly influenced by runoff, which is higher in the mountainous part of the studied basins. The identification of chemical weathering regimes from our study confirmed the weathering potential and complexity of temperate watersheds in arid environment and that additional studies of these terrains are warranted. However, because the dominant weathering reactions in the sedimentary platform of northern Xinjiang are of carbonates and evaporites rather than silicate minerals, and the climatic factors have important role on the rock weathering regimes, we think that weathering at the arid temperate drainage system (Central Asia) is maybe not an important long-term sink for atmospheric CO2, if the future climate has no great change.

Zhu, Bingqi; Yu, Jingjie; Qin, Xiaoguang; Rioual, Patrick; Zhang, Yichi; Liu, Ziting; Mu, Yan; Li, Hongwei; Ren, Xiaozong; Xiong, Heigang

2013-04-01

316

Estimating Impacts of Reforestation on Water Outflow and Sediment Load in a Watershed from Lower Mississippi River Alluvial Valley  

NASA Astrophysics Data System (ADS)

Lower Mississippi River Alluvial Valley (LMRAV) is one of the most disturbed by human activities among the world largest coastal and river basins. This study estimated the impacts of reforestation on water outflow attenuation (i.e., water flow out of the watershed outlet) and sediment load reduction in the Lower Yazoo River Watershed (LYRW) within the LMRAV using the US-EPA's BASINS-HSPF model. The model was calibrated and validated with available experimental data prior to its application. Two simulation scenarios were then performed: one was chosen to predict the water outflow and sediment load without reforestation and the other was selected to project the potential impacts of reforestation upon water outflow attenuation and sediment load reduction following the conversion of 25, 50, 75, and 100% of the agricultural lands with most lands near or in the batture of the streams. Comparison of the two simulation scenarios (i.e., with and without reforestation) showed that a conversion of agricultural land into forests attenuated water outflow and reduced sediment load. In general, a two-fold increase in forest land area resulted in approximately a two-fold reduction in annual water outflow volume and sediment load mass, which occurred because forests absorb water and reduce surface water runoff and prevent soil erosion. On average, over a 10-year simulation, the specific water outflow attenuation and sediment load reduction were, respectively, 250m3/ha/y and 4.02 metric ton/ha/y. Seasonal variations of water outflow attenuation and sediment load reduction occurred with the maximum attenuation/reduction in winter and the minimum attenuation/reduction in summer. Our load duration curve analysis further confirmed that an increase in forest land area reduced the likelihood of a given sediment load out of the watershed outlet. This study suggests that reforestation in or around the batture of streams is a useful practice for water outflow attenuation and sediment load reduction.

Ouyang, Y.; Leininger, T.; Moran, M.

2013-12-01

317

Heavy metals in Ratnapura alluvial gem sediments, Sri Lanka  

NASA Astrophysics Data System (ADS)

The valuable gems in Sri Lanka are found from the sedimentary gem deposits in Ratnapura District, which are found as alluvial deposits some are about >50 m deep. Gem bearing gravel layer is taken out from the mine, washed by panning to recover the gem minerals in the heavy mineral fraction, is a common practice in the gem mining area. Gem bearing sediment layer is associated with different heavy minerals in which different trace metals as Co, Cr, Cu, Al, Zr, Pb and As also can be present. During panning, the sediment is washed away and the heavy metals attached to the sediments are released into the environment. Hence we studied the lability and bioavailability of arsenic and other heavy metals from the gem sediments. Sediment samples were collected from 15 small scale gem mines (3 soil layers- top, gem mineral layer and layer below gem bearing gravel layer), air dried and sieved to obtain <63?m fraction. Bioavailable, exchangeable and residual fractions were 0.01M CaCl2, 1M NaOAc, pH 8.2 and microwave digestion using HF, HNO3 and HClO4. Filtered samples were analyzed for As, Co, Zn, Mn, Cu, Ni, Pb and Fe using atomic absorption spectrophotometer (GBC 933AA). Total digestion results in different layers indicated that heavy metals show an increasing pattern with depth. About 4 gem bearing gravel layers were consist of high concentrations of Ni (>150 mg/kg), Cu (>150 mg/kg), Pb (>400 mg/kg), Zn (>600 mg/kg) and Co ions (>100 mg/kg). Arsenite in the gem sediments were low and recorded as <5mg/kg. Total arsenic analysis is under investigation. Highest concentrations for bioavailable and exchangeable (leach to water) metals were Fe>Co>Zn>Mn>Ni>Cu>Pb. Sediments from few gem pits showed considerably high concentrations of metals analyzed. In some places Fe, Ni, Cu, Zn reported high in bioavailable fractions 70, 25, 20, 10 mg/kg respectively. Mobilization of these metals may increase due to changes in the pH and the presence of other ions in the environment. High concentrations of toxic metals in exchangeable and bioavailable fractions indicate the risk on plant and animals as well as the open water bodies and groundwater sources.

Vithanage, M. S.; Hettiarachchi, J. K.; Rajapaksha, A. U.; Wijesekara, H.; Hewawasam, T.

2011-12-01

318

Effects of potential surface coal mining on dissolved solids in Otter Creek and in the Otter Creek alluvial aquifer, southeastern Montana  

USGS Publications Warehouse

Otter Creek drains an area of 709 square miles in the coal-rich Powder River structural basin of southeastern Montana. The Knobloch coal beds in the Tongue River Member of the Paleocene Fort Union Formation is a shallow aquifer and a target for future surface mining in the downstream part of the Otter Creek basin. A mass-balance model was used to estimate the effects of potential mining on the dissolved solids concentration in Otter Creek and in the alluvial aquifer in the Otter Creek valley. With extensive mining of the Knobloch coal beds, the annual load of dissolved solids to Otter Creek at Ashland at median streamflow could increase by 2,873 tons, or a 32-percent increase compared to the annual pre-mining load. Increased monthly loads of Otter Creek, at the median streamflow, could range from 15 percent in February to 208 percent in August. The post-mining dissolved solids load to the subirrigated part of the alluvial valley could increase by 71 percent. The median dissolved solids concentration in the subirrigated part of the valley could be 4,430 milligrams per liter, compared to the pre-mining median concentration of 2,590 milligrams per liter. Post-mining loads from the potentially mined landscape were calculated using saturated-paste-extract data from 506 overburdened samples collected from 26 wells and test holes. Post-mining loads to the Otter Creek valley likely would continue at increased rates for hundreds of years after mining. If the actual area of Knobloch coal disturbed by mining were less than that used in the model, post-mining loads to the Otter Creek valley would be proportionally smaller. (USGS)

Cannon, M.R.

1985-01-01

319

Evaluation of genetic programming-based models for simulating friction factor in alluvial channels  

NASA Astrophysics Data System (ADS)

The bed resistance is one of the most complex aspects of water flow studies in natural streams. Most of the existing non-linear formulas for describing alluvial channel flows are based on dimensional analysis and statistical fitting of data to the parameters considered in the functional relationships implicitly, which are partially valid. The present study aims at developing genetic programming (GP) - based formulation of Manning roughness coefficient in alluvial channels. The training and testing data are selected from original experiments, performed in a hydraulic flume using a sand mobile bed. A comparison was also made between GP and traditional nonlinear approaches of resistance modeling. The obtained results revealed the GP capability in modeling resistance coefficient of alluvial channels' bed.

Roushangar, Kiyoumars; Mouaze, Dominique; Shiri, Jalal

2014-09-01

320

Predicting the Future Impact of Droughts on Ungulate Populations in Arid and Semi-Arid Environments  

PubMed Central

Droughts can have a severe impact on the dynamics of animal populations, particularly in semi-arid and arid environments where herbivore populations are strongly limited by resource availability. Increased drought intensity under projected climate change scenarios can be expected to reduce the viability of such populations, yet this impact has seldom been quantified. In this study, we aim to fill this gap and assess how the predicted worsening of droughts over the 21st century is likely to impact the population dynamics of twelve ungulate species occurring in arid and semi-arid habitats. Our results provide support to the hypotheses that more sedentary, grazing and mixed feeding species will be put at high risk from future increases in drought intensity, suggesting that management intervention under these conditions should be targeted towards species possessing these traits. Predictive population models for all sedentary, grazing or mixed feeding species in our study show that their probability of extinction dramatically increases under future emissions scenarios, and that this extinction risk is greater for smaller populations than larger ones. Our study highlights the importance of quantifying the current and future impacts of increasing extreme natural events on populations and species in order to improve our ability to mitigate predicted biodiversity loss under climate change. PMID:23284700

Duncan, Clare; Chauvenet, Alienor L. M.; McRae, Louise M.; Pettorelli, Nathalie

2012-01-01

321

Remote sensing parameterization of land surface heat fluxes over arid and semi-arid areas  

NASA Astrophysics Data System (ADS)

Dealing with the regional land surfaces heat fluxes over inhomogeneous land surfaces in arid and semi-arid areas is an important but not an easy issue. In this study, one parameterization method based on satellite remote sensing and field observations is proposed and tested for deriving the regional land surface heat fluxes over inhomogeneous landscapes. As a case study, the method is applied to the Dunhuang experimental area and the HEIFE (Heihe River Field Experiment, 1988 1994) area. The Dunhuang area is selected as a basic experimental area for the Chinese National Key Programme for Developing Basic Sciences: Research on the Formation Mechanism and Prediction Theory of Severe Climate Disaster in China (G1998040900, 1999 2003). The four scenes of Landsat TM data used in this study are 3 June 2000, 22 August 2000, and 29 January 2001 for the Dunhuang area and 9 July 1991 for the HEIFE area. The regional distributions of land surface variables, vegetation variables, and heat fluxes over inhomogeneous landscapes in arid and semi-arid areas are obtained in this study.

Ma, Yaoming; Wang, Jiemin; Huang, Ronghui; Wei, Guoan; Menenti, Massimo; Su, Zhongbo; Hu, Zeyong; Gao, Feng; Wen, Jun

2003-07-01

322

Responses of terrestrial aridity to global warming  

NASA Astrophysics Data System (ADS)

dryness of terrestrial climate can be measured by the ratio of annual precipitation (P) to potential evapotranspiration (PET), where the latter represents the evaporative demand of the atmosphere, which depends on the surface air temperature, relative humidity, wind speed, and available energy. This study examines how the terrestrial mean aridity responds to global warming in terms of P/PET using the Coupled Model Intercomparison Project phase 5 transient CO2 increase to 2 × CO2 simulations. We show that the (percentage) increase (rate) in P averaged over land is ~1.7%/°C ocean mean surface air temperature increase, while the increase in PET is 5.3%/°C, leading to a decrease in P/PET (i.e., a drier terrestrial climate) by ~3.4%/°C. Noting a similar rate of percentage increase in P over land to that in evaporation (E) over ocean, we propose a framework for examining the change in P/PET, in which we compare the change in PET over land and E over ocean, both expressed using the Penman-Monteith formula. We show that a drier terrestrial climate is caused by (i) enhanced land warming relative to the ocean, (ii) a decrease in relative humidity over land but an increase over ocean, (iii) part of increase in net downward surface radiation going into the deep ocean, and (iv) different responses of PET over land and E over ocean for given changes in atmospheric conditions (largely associated with changes in temperatures). The relative contributions to the change in terrestrial mean aridity from these four factors are about 35%, 35%, 15%, and 15%, respectively. The slight slowdown of the surface wind over both land and ocean has little impact on the terrestrial mean aridity.

Fu, Qiang; Feng, Song

2014-07-01

323

Patterns of human occupation during the early Holocene in the Central Ebro Basin (NE Spain) in response to the 8.2 ka climatic event  

Microsoft Academic Search

The Central Ebro River Basin (NE Spain) is the most northern area of truly semi-arid Mediterranean climate in Europe and prehistoric human occupation there has been strongly influenced by this extreme environmental condition. Modern climate conditions single out this region due to the harsh environment, characterised by the highest absolute summer temperatures of the Ebro River Basin. The Bajo Aragón

P. González-Sampériz; P. Utrilla; C. Mazo; B. Valero-Garcés; Mc. Sopena; M. Morellón; M. Sebastián; A. Moreno; M. Martínez-Bea

2009-01-01

324

Geomorphic changes upstream of beaver dams in Bridge Creek, an incised stream channel in the interior Columbia River basin, eastern Oregon  

Microsoft Academic Search

Channel incision is a widespread phenomenon throughout the dry interior Columbia River basin and other semi-arid regions of the world, which degrades stream habitat by funda- mentally altering natural ecological, geomorphological and hydrological processes. We examined the extent of localized aggradation behind beaver dams on an incised stream in the interior Columbia River basin to assess the potential for using

Michael M. Pollock; Timothy J. Beechie; Chris E. Jordan

2007-01-01

325

Use of composts in revegetating arid lands  

SciTech Connect

Compost has been suggested as a soil amendment for arid lands at the US Department of Energy's Hanford Site in southeastern Washington State. The operating contractor of the site, Westinghouse Hanford Company, requested that the Pacific Northwest Laboratory conduct a literature review to compile additional information on the use of compost amendments and their benefits. This report provides background information on the factors needed for plant growth and the consequences of severe soil disturbance. This report also discussed the characteristics of composts relative to other amendments and how they each affect plant growth. Finally,regulatory requirements that could affect land application of sludge-based compost on the Hanford Site are reviewed.

Brandt, C.A.; Hendrickson, P.L.

1991-09-01

326

Changes of climate extremes in a typical arid zone: Observations and multimodel ensemble projections  

NASA Astrophysics Data System (ADS)

This article presents an analysis of the spatiotemporal changes (1960-2100) in temperature and precipitation extremes of a typical arid zone (i.e., the Tarim River Basin) in Central Asia. The latest observations in the past five decades (1960-2009) and Coupled General Circulation Model (CGCM) multimodel ensemble projections (2010-2100) using the Bayesian Model Average (BMA) approach are employed for analysis in this study. Results indicate: (1) Most warm (cold) extreme temperature indices have shown significantly positive (negative) trends in the Tarim River Basin in past five decades, while only slight changes in precipitation extremes can be observed. From the spatial perspective, more significantly warm (cold) extremes are found in the desert zones than in upstream mountain zones (i.e., the Tian Shan Mountain and Kunlun Mountain systems which surround the basin). Whereas, there are no identical spatial patterns for the change in extreme precipitation; (2) Ensemble of five CGCM models in Phase 3 of the Coupled Model Intercomparison Project (CMIP3) based on the BMA method suggests that the increasing consecutive dry days (CDD), together with the decreasing frost day (FD) and increasing warm nights frequency (TN90) may lead to more frequent droughts in Tarim in future. Meanwhile, slight increase of annual count of days with precipitation of more than 10 mm (R10), maximum 5-day precipitation total (R5D), simple daily intensity index (SDII), and annual total precipitation with precipitation >95th percentile (R95) in projections indicate a probability of flood occurrence in summer together with frequent occurrence of droughts. The results can provide beneficial reference to water resource and eco-environment management strategies in arid zones for associated policymakers and stakeholders.

Yang, Tao; Wang, Xiaoyan; Zhao, Chenyi; Chen, Xi; Yu, Zhongbo; Shao, Quanxi; Xu, Chong-Yu; Xia, Jun; Wang, Weiguang

2011-10-01

327

Seismic mapping of alluvial fans and sub-fan bedrock in Big Bend National Park, Texas  

E-print Network

of the hydrogeology of alluvium covering an area of more than 40 square miles requires a multi-phase approach. Phase one was completed by Archer (1982). That effort involved the detailed study of a single alluvial fan to determine the most effective use of instru... of the hydrogeology of alluvium covering an area of more than 40 square miles requires a multi-phase approach. Phase one was completed by Archer (1982). That effort involved the detailed study of a single alluvial fan to determine the most effective use of instru...

Monti, Joseph

2012-06-07

328

Sediment geochemistry and tectonic setting: Application of discrimination diagrams to early stages of intracontinental rift evolution, with examples from the Okavango and Southern Tanganyika rift basins  

Microsoft Academic Search

In this article, we have applied discriminant diagrams and bivariate plots for tectonic setting to Quaternary sediments from the East African Rift System (EARS). Sediment samples used in this study represent two different phases in early stage intracontinental rift evolution: the alluvial fan of the nascent Okavango system and a lacustrine basin within the relatively more mature Tanganyika system. The

P. Huntsman-Mapila; J.-J. Tiercelin; M. Benoit; S. Ringrose; S. Diskin; J. Cotten; C. Hémond

2009-01-01

329

Reconciling Holocene Alluvial Records in Buckskin Wash, Utah--Where do Arroyo Cycles end and Paleofloods Begin?  

Microsoft Academic Search

Drainages that undergo arroyo cut-and-fill cycles clearly change their grade over time, probably in response to climatic forcing. Reconstructions of this behavior are usually based on alluvial records found in broad alluvial valleys. Conversely, paleoflood hydrologists have constructed flood records by studying slackwater deposits preserved in nearby bedrock canyons, typically assuming a constant grade over millennial timescales. These contrasting approaches

J. E. Harvey; J. Pederson; T. Rittenour

2008-01-01

330

Uses of tree legumes in semi-arid regions  

SciTech Connect

Uses of tree legumes in semi-arid and arid regions are reviewed. This review is divided into sections according to the following general use categories: fuels; human food; livestock food; to increase yields of crops grown beneath their canopies;and control of desertification. (MHR)

Felker, P.

1980-01-01

331

ENVIRONMENTAL MONITORING AND ASSESSMENT PROGRAM - ARID ECOSYSTEMS 1992 PILOT REPORT  

EPA Science Inventory

The Environmental Monitoring and Assessment Program (EMAP) is being implemented to provide quantitative assessments of status and trends in the condition of ecological resources within the United States. n 1992 the EMAP Arid Ecosystems Resource Group (EMAP-Arid) conducted a pilot...

332

PROBLEMS OF ADAPTATION OF PASTORAL BUSINESSES IN THE ARID ZONE  

Microsoft Academic Search

With emphasis upon Central Australia, an assessment is made of the economic problems of pastoral firms in meeting the climatic conditions of the arid zone. Analysis ranges over the responsibility for conservation and drought planning, the inadequacy of a purely physical approach to conservation, the difficulties of station organization and management in the arid zone, the array of possible managerial

Keith O. Campbell

1966-01-01

333

A stable isotope aridity index for terrestrial environments  

E-print Network

composition of tooth enamel from multiple mammalian taxa across eastern Africa to present a proxy for aridity. Here we report tooth enamel 18O values of 14 species from 18 locations and classify them according sensitive (ES) and evaporation insensitive (EI). Tooth enamel 18O values of ES animals increase with aridity

Ehleringer, Jim

334

Feast to famine: Sediment supply control on Laramide basin fill  

NASA Astrophysics Data System (ADS)

Erosion of Laramide-style uplifts in the western United States exerted an important first-order influence on Paleogene sedimentation by controlling sediment supply rates to adjacent closed basins. During the latest Cretaceous through Paleocene, these uplifts exposed thick intervals of mud-rich Upper Cretaceous foreland basin fill, which was quickly eroded and redeposited. Cretaceous sedimentary lithologies dominate Paleocene conglomerate clast compositions, and the volume of eroded foreland basin strata is approximately twice the volume of preserved Paleocene basin fill. As a result of this sediment oversupply, clastic alluvial and paludal facies dominate Paleocene strata, and are associated with relatively shallow and ephemeral freshwater lake facies. In contrast, large, long-lived, carbonate-producing lakes occupied several of the basins during the Eocene. Basement-derived clasts (granite, quartzite, and other metamorphic rocks) simultaneously became abundant in lower Eocene conglomerate. We propose that Eocene lakes developed primarily due to exposure of erosion-resistant lithologies within cores of Laramide uplifts. The resultant decrease in erosion rate starved adjacent basins of sediment, allowing the widespread and prolonged deposition of organic-rich lacustrine mudstone. These observations suggest that geomorphic evolution of the surrounding landscape should be considered as a potentially important influence on sedimentation in many other interior basins, in addition to more conventionally interpreted tectonic and climatic controls.

Carroll, Alan R.; Chetel, Lauren M.; Elliot Smith, M.

2006-03-01

335

Nest survival of forest birds in the Mississippi Alluvial Valley  

USGS Publications Warehouse

In the Mississippi Alluvial Valley, flood control has led to a drastic reduction in the area of forest habitat and altered the patchwork of forest cover types. Silvicultural management of the remaining fragmented forests has changed to reflect the altered hydrology of the forests, current economic conditions of the area, and demand for forest products. Because forest type and silvicultural management impact forest birds, differences in avian productivity within these forests directly impact bird conservation. To assist in conservation planning, we evaluated daily nest survival, nest predation rates, and brood parasitism rates of forest birds in relation to different forest cover types and silvicultural management strategies within this floodplain. Within bottomland hardwood forests, nest success of blue-gray gnatcatcher (Polioptila caerulea, 13%), eastern towhee (Pipilo erythrophthalmus, 28%), indigo bunting (Passerina cyanea, 18%), northern cardinal (Cardinalis cardinalis, 22%), and yellow-billed cuckoo (Coccyzus americanus, 18%) did not differ from that within intensively managed cottonwood plantations. However, average daily survival of 542 open-cup nests of 19 bird species in bottomland hardwoods (0.9516 + 0.0028, -27% nest success) was greater than that of 543 nests of 18 species in cotlonwood plantations (0.9298 + 0.0035, -15% nest success). Differences in daily nest survival rates likely resulted from a combination of differences in the predator community--particularly fire ants (Solenopsis invicta)--and a marked difference in species composition of birds breeding within these 2 forest types. At least 39% of nests in bottomland hardwood forests and 65% of nests in cottonwood plantations were depredated. Rates of parasitism by brown-headed cowbirds (Molothrus ater) were greater in managed cottonwoods (24%) than in bottomland hardwoods (9%). Nest success in planted cottonwood plantations for 18 species combined (-14%), and for yellow-breasted chat (Icteria vimns, 7%), eastern towhee (14%), indigo bunting (14%), and northern cardinal (17%) did not differ from nest success in cottonwood plantations that were coppiced from root sprouts following pulpwood harvest. Within bottomland hardwood forests, uneven-aged group-selection timber harvest reduced the combined daily nest survival of all species from 0.958 to 0.938, which reduced nest success by about 14%. Specifically, timber harvest reduced nest success of species that nest in the forest midstory and canopy, such as Acadian flycatcher (Empidonax virescens)--from 32% before harvest to 14% after harvest. Conversely, those species that nest primarily in the shrubby understory--such as northern cardinal--were not affected by timber harvest and maintained an overall nest success of about 33%. Thus, birds nesting in the understory of bottomland hardwood forests are not adversely impacted by selective timber harvest, but there is a short-term reduction in nest success for birds that nest in the canopy and midstory.

Twedt, D.J.; Wilson, R.R.; Henne-Kerr, J.L.; Hamilton, R.B.

2001-01-01

336

Alluvial deposits and plant distribution in an Amazonian lowland megafan  

NASA Astrophysics Data System (ADS)

A large volume of sandy alluvial deposits (> 1000 km2) characterizes a flat wetland in northern Amazonia. These have been recently described as the sedimentary record of a megafan system, which have a distinct triangular shape produced by highly migratory distributary rivers. The vegetation map suggests that this megafan is dominated by open vegetation in sharp contact with the surround rainforest. Understanding the relationship between geomorphological processes and vegetation distribution is crucial to decipher and conserve the biodiversity in this Amazonian ecosystem. In this study we interpret plant dynamics over time, and investigate its potential control by sedimentary processes during landscape evolution. The study area is located in the Viruá National Park. Two field campaigns were undertaken in the dry seasons of 2010 and 2011 and the sampling sites were selected by combining accessibility and representativeness. Vegetation contrasts were recorded along a transect in the medial section of the Viruá megafan. Due to the absence of outcrops, samples were extracted using a core device, which allowed sampling up to a depth of 7.5 m. All cores were opened and described in the field, with 5 cm3 samples collected at 20 cm intervals. The ?13C of organic matter was used as a proxy to distinguish between C3 and C4 plant communities. The chronology was established based on radiocarbon dating. The results suggest that the cores from forested areas show the most depleted values of ?13C, ranging from -32.16 to -27.28‰. The ?13C curve in these areas displays typical C3 land plant values for the entire record, which covers most of the Holocene. This finding indicates that either the vegetation remained stable over time or the sites were dominated by aquatic environments with freshwater plants before forest establishment. The cores from the open vegetation areas show a progressive upward enrichment in ?13C values, which range from -28.50 to -19.59‰. This trend is more pronounced after de mid-Holocene, suggesting that the open vegetation, represented mostly by C4 land plants, evolved only more recently. Based on our isotope data, a model is proposed taking into account the influence of sedimentary dynamics on the modern pattern of plan distribution. The establishment of open vegetation occurred at different times depending on location over the megafan area, varying from around 3,000 to 6,400 cal yrs BP. As sedimentation took place, areas located far from the surrounding rainforest were prone to inputs of organic matter derived from open vegetation, whereas the contribution of organic matter derived from arboreous vegetation increases toward the areas located closer to the rainforest. In general, open vegetation is constrained to depositional sites that remained active until relatively recent Holocene times, while surrounding areas with a relatively older geological history are covered by dense forest. The results presented here consist in a striking example of the influence of sedimentary processes during the Late Pleistocene-Holocene on the development of modern plants of this Amazonian lowland.

Zani, H.; Rossetti, D.; Cremon; Cohen, M.; Pessenda, L. C.

2012-12-01

337

Basin-wide Holocene environmental changes in the marginal area of the Asian monsoon, northwest China  

Microsoft Academic Search

In arid regions, because of spatial variability, using single climate records is difficult to reconstruct the past climate\\u000a change for the drainage basins. Holocene environmental records were collected from the upper, middle and lower regions of\\u000a the Shiyang River drainage basin in the marginal area of the Asian monsoon (northwest China). The main objective of this paper\\u000a was to compare

Yu LiNai; Nai’ang Wang; Zhuolun Li; Hua’an Zhang

338

Mountains and arid climates of middle latitudes  

SciTech Connect

Simulations from a global climate model with and without orography have been used to investigate the role of mountains in maintaining extensive arid climates in middle latitudes of the Northern hemisphere. Dry climates similar to those observed were simulated over central Asia and western interior North America in the experiment with mountains, whereas relatively moist climates were simulated in these areas in the absence of orography. The experiments suggest that these interior regions are dry because general subsidence and relatively infrequent storm development occur upstream of orographically induced stationary wave troughs. Downstream of these troughs, precipitation-bearing storms develop frequently in association with strong jet streams. In contrast, both atmospheric circulation and precipitation were more zonally symmetric in the experiment without mountains. In addition, orography reduces the moisture transport into the continental interiors from nearby oceanic sources. The relative soil wetness of these regions in the experiment without mountains is consistent with paleoclimatic evidence of less aridity during the late Tertiary, before substantial uplift of the Rocky Mountains and Tibetan Plateau is believed to have occurred.

Manabe, S.; Broccoli, A.J. (Princeton Univ., NJ (USA))

1990-01-12

339

Environmental controls on perennial and ephemeral carbonate lakes: the central palaeo-Andean Basin of Bolivia during Late Cretaceous to early Tertiary times  

Microsoft Academic Search

In the central palaeo-Andean Basin (Potosí Basin) of Bolivia, the up to 450-m-thick El Molino Formation (Campanian-Maastrichtian to early Tertiary) includes two main carbonate lacustrine episodes each of different extent and duration. These episodes are separated by an extensive development of alluvial facies (floodplain deposits) and limestones deposited in playa lakes or isolated ponds. The El Molino Formation has been

Gilbert Camoin; Joël Casanova; Jean-Marie Rouchy; Marie-Madeleine Blanc-Valleron; Jean-François Deconinck

1997-01-01

340

Desert evolution and climatic changes in the Tarim River basin since 12 ka BP  

Microsoft Academic Search

Climatic changes in the Tarim River basin since 12 kaBP were divided into four stages based on the analyses of sedimentary\\u000a phase, the features of some climatic and environmental biomarks in the sedimentary strata and desert evolution. During the\\u000a Holocene, cool-dry and temperate-dry climates resulted in apparent alluvial-fluvial and weak aeolian activities. During 10–8\\u000a kaBP, the climate was dry and

Qi Feng; Huijun Jin; Zhizhu Su

1999-01-01

341

Predicting Reservoir Quality in the Cretaceous Maceio Member of the Sergipe - Alagoas Basin, Northeast Brazil  

Microsoft Academic Search

Fifty-one cores were studied to determine the porosity and permeability of the sandstones of the Cretaceous Maceio Member of the Muribeca Formation in the northeastern half of the Sergipe-Alagoas basin of Brazil's passive continental margin. Here, the Maceio Member is a feldspar-rich sandstone that thickens offshore to more than 5,000 m. The Maceio includes seven facies ranging from alluvial to

Carlos de Abreu; P. E. Potter

1990-01-01

342

Diagenetic contrast of sandstones in hydrocarbon prospective Mesozoic rift basins (Ethiopia, UK, USA)  

NASA Astrophysics Data System (ADS)

Diagenetic studied in hydrocarbon-prospective Mesozoic rift basins were carried out in the Blue Nile Basin (Ethiopia), Ulster Basin (United Kingdom) and Hartford Basin (United States of America). Alluvial fan, single and amalgamated multistorey meandering and braided river, deep and shallow perennial lake, shallow ephemeral lake, aeolian and playa mud-flat are the prominent depositional environments. The studied sandstones exhibit red bed diagenesis. Source area geology, depositional environments, pore-water chemistry and circulation, tectonic setting and burial history controlled the diagenetic evolution. The diagenetic minerals include: facies-related minerals (calcrete and dolocrete), grain-coating clay minerals and/or hematite, quartz and feldspar overgrowths, carbonate cements, hematite, kaolinite, illite-smectite, smectite, illite, chlorite, actinolite, laumontite, pyrite and apatite. Diversity of diagenetic minerals and sequence of diagenetic alteration can be directly related to depositional environment and burial history of the basins. Variation in infiltrated clays, carbonate cements and clay minerals observed in the studied sandstones. The alluvial fan and fluviatile sandstones are dominated by kaolinite, illite calcite and ferroan calcite, whereas the playa and lacustrine sandstones are dominated by illite-smectite, smectite-chlorite, smectite, chlorite, dolomite ferroan dolomite and ankerite. Albite, pyrite and apatite are predominantly precipitated in lacustrine sandstones. Basaltic eruption in the basins modified mechanically infiltrated clays to authigenic clays. In all the studied sandstones, secondary porosity predominates over primary porosity. The oil emplacement inhabited clay authigenesis and generation of secondary porosity, whereas authigenesis of quartz, pyrite and apatite continued after oil emplacement.

Wolela, A.

2014-11-01

343

Effects of Land Use and Hydrogeology on the Water Quality of Alluvial Aquifers in Eastern Iowa and Southern Minnesota, 1997  

USGS Publications Warehouse

Ground-water samples were collected from monitoring wells at 31 agricultural and 30 urban sites in the Eastern Iowa Basins study unit during June-August 1997 to evaluate the effects of land use and hydrogeology on the water quality of alluvial aquifers. Ground-water samples were analyzed for common ions, nutrients, dissolved organic carbon, tritium, radon-222, pesticides and pesticide metabolites, volatile organic compounds, and environmental isotopes. Calcium, magnesium, and bicarbonate were the dominant ions in most samples and were likely derived from solution of carbonate minerals (calcite and dolomite) present in alluvial detrital deposits. Chloride and nitrate were dominant anions in samples from several wells. Sodium and chloride concentrations were significantly higher in samples from urban areas, where roads are more numerous and road salts may be more frequently applied, than in agricultural areas. Nitrate was detected in 94 percent of samples from agricultural areas and 77 percent of samples from urban areas. Nitrate concentrations were significantly higher in agricultural areas than in urban areas and exceeded the U.S. Environmental Protection Agency maximum contaminant level for drinking water (10 milligrams per liter as N) in 39 percent of samples from agricultural areas. Nitrate concentrations in samples from urban areas did not exceed the maximum contaminant level. Greater use of fertilizers in agricultural areas most likely contributes to higher nitrate concentrations in samples from those areas. Tritium-based ages indicate ground water was most likely recharged after the 1950's at all but one sampling site. Agricultural and urban land-use areas have remained relatively stable in the study area since the 1950's; therefore, the effects of current land use should be reflected in ground water sampled during this study. Radon-222 was detected in all samples and exceeded the U.S. Environmental Protection Agency's previously proposed maximum contaminant level for drinking water (300 picocuries per liter) in 71 percent of samples. Pesticides were detected in 84 percent of samples from agricultural areas and 70 percent from urban areas. Atrazine and metolachlor were the most frequently detected pesticides in samples from agricultural areas; atrazine and prometon were the most frequently detected pesticides in samples from urban areas. None of the pesticide concentrations exceeded U.S. Environmental Protection Agency maximum contaminant levels or lifetime health advisories for drinking water. Pesticide metabolites were detected in 94 percent of samples from agricultural areas and 53 percent from urban areas. Metolachlor ethane sulfonic acid and deethylatrazine were the most frequently detected metabolites in samples from agricultural areas; metolachlor ethane sulfonic acid and alachlor ethane sulfonic acid were the most frequently detected metabolites in samples from urban areas. Total metabolite concentrations were significantly higher in samples from agricultural areas than in samples from urban areas. Total pesticide concentrations (parent compounds) tended to be higher in samples from agricultural areas; however, this difference was not statistically significant. Metabolites constituted the major portion of the total residue concentration in the alluvial aquifer. Volatile organic compounds were detected in 40 percent of samples from urban areas and 10 percent from agricultural areas. Methyl tertbutyl ether was the most commonly detected volatile organic compound and was present in 23 percent of samples from urban areas. Elevated concentrations (greater than 30 micrograms per liter) of methyl tert-butyl ether and BTEX compounds (benzene, toluene, ethylbenzene, and xylene) in two samples from urban areas suggest the possible presence of point-source gasoline leaks or spills. Factors other than land use may contribute to observed differences in water quality between and within agricultural and urban

Savoca, Mark E.; Sadorf, Eric M.; Linhart, S. Mike; Akers, Kim K.B.

2000-01-01

344

A modified climate diagram displaying net water requirements of wetlands in arid and semi-arid regions  

Microsoft Academic Search

Flooding regimes in arid and semi-arid regions are heavily influenced by climate change and water shortage, water regulations, and increased water demands. Wetlands managed as part of regulated water systems in agricultural landscapes often require external water supplies to sustain or support desired properties or services. Therefore, water resource managers must weigh water requirements necessary to support wetland functions alongside

Z. Jia; W. Luo

2009-01-01

345

BIOGEOGRAPHIC IMPLICATIONS OF RECENT LOW-ELEVATION RECOLONIZATION BY NEOTOMA CINEREA IN THE GREAT BASIN  

Microsoft Academic Search

Homestead Cave, a paleontological site located in a low-elevation arid setting in the north- ern Bonneville Basin of northcentral Utah, documents the local extinction of Neotoma cinerea during the Middle Holocene. N. cinerea is present there today, and the Homestead Cave record suggests that recolonization likely occurred sometime prior to 1,000 years ago. This history supports the view (forwarded by

Donald K. Grayson; David B. Madsen

2000-01-01

346

Estimating discharge of shallow groundwater by transpiration from greasewood in the Northern Great Basin  

Microsoft Academic Search

Evapotranspiration from bare soil and phreatophytes is a principal mechanism of groundwater discharge in arid and semiarid regions of the midwestern and western United States including the Great Basin. The imbalance between independent estimates of groundwater recharge from precipitation and of groundwater discharge based on estimates of groundwater evapotranspiration leads to large uncertainties in groundwater budgets. Few studies have addressed

William D. Nichols

1993-01-01

347

pecos river basin wpp implementation The Pecos River winds more than 900 miles through semi-  

E-print Network

pecos river basin wpp implementation The Pecos River winds more than 900 miles through semi- arid with abundant water to irrigate crops and water livestock. Today, the river's flow has dwindled to a trickle in many instances, and dissolved oxy- gen (DO) levels in portions of the river do not meet Texas' water

348

Petrographically deduced triassic climate for the Deep River Basin, eastern piedmont of North Carolina  

SciTech Connect

A petrographic comparison of Triassic, fluvial sandstones from the Deep River Basin in the eastern piedmont of North Carolina with nearby Holocene stream sands (1) indicates that he Triassic climate was more arid than today's and (2) distinguishes an eastern, more plutonic terrane from a western, more metamorphic source terrane. The paleoclimatic interpretation is based on differences in framework composition between modern and ancient sands of the same grain size, derived from the same rock type, transported similar distances and deposited in similar settings. The Triassic sandstones contain more lithic-fragments but less quartz than otherwise equivalent, modern sand in the Deep River Basin. Feldspar content is more complex, controlled by both source-rock composition and climate. Sand from the more plutonic terrane contains more feldspar and plutonic lithic-fragments than sand from the more metamorphic terrane, which contains more quartz and metamorphic lithic-fragments. This petrographic interpretation of the Triassic sandstones along with the presence of coal, limestone, chert and caliche in the middle of the section suggests that the Triassic climate was cyclic, changing from arid to humid and back to arid. Plate-tectonic reconstructions place the Deep River Basin between the Triassic equator and Tropic of cancer, where the easterly trade winds would predominate. Therefore, the arid portions of the cycle could have been due to a periodic, orographic, rain shadow formed as the result of intermittent movement along the Jonesboro Fault, creating a highland area east of the Deep River Basin.

McCarn, S.T.; Mansfield, C.F.

1985-01-01

349

Introduction to the Special Section on Alternative Futures for Great Basin Ecosystems  

Microsoft Academic Search

Natural and anthropogenic processes are causing exten- sive and rapid ecological, social, and economic changes in arid and semiarid ecosystems worldwide. Nowhere are these changes more evident than in the Great Basin of the western United States, a region of 400,000 km2 that largely is managed by federal agencies. Major drivers of ecosys- tems and human demographics of the Great

Erica Fleishman; Jeanne C. Chambers; Michael J. Wisdom

2009-01-01

350

Effects of livestock grazing on nutrient retention in a headwater stream of the Rio Basin  

E-print Network

Effects of livestock grazing on nutrient retention in a headwater stream of the Rio Basin Mark A-arid Southwest have been attributed to both over-grazing by livestock and to climatic cycles that influence arroyo forma- tion. Considerable effort has been directed toward the influence of livestock grazing

351

Luminescence and radiocarbon chronologies of playa sedimentation in the Murray Basin, southeastern Australia  

Microsoft Academic Search

Playa lakes are important palaeoenvironmental repositories in arid landscapes. As geochemically open and organically poor systems, however, accurate dating of playa sequences is often hampered. This study paired accelerator mass spectrometry radiocarbon (AMS 14C) and optically stimulated luminescence (OSL) ages from four Murray Basin playa lakes to assess the accuracy of the chronometric techniques in these environments. The OSL dating

Matthew L. Cupper

2006-01-01

352

A Conceptual Framework for SAHRA Integrated Multi-resolution Modeling in the Rio Grande Basin  

Microsoft Academic Search

The sustainable management of water resources in a river basin requires an integrated analysis of the social, economic, environmental and institutional dimensions of the problem. Numerical models are commonly used for integration of these dimensions and for communication of the analysis results to stakeholders and policy makers. The National Science Foundation Science and Technology Center for Sustainability of semi-Arid Hydrology

Y. Liu; H. Gupta; E. Springer; T. Wagener; D. Brookshire; C. Duffy

2004-01-01

353

Characteristics of bedrock-alluvial anastomosed rivers: the Mekong River in Cambodia  

Microsoft Academic Search

The Mekong River is the 12th largest river in the world in terms of its length and mean annual discharge and yet it is poorly investigated. In the north eastern regions of Cambodia the Mekong River develops a multichannel pattern. It is characterised by a complex of intersecting bedrock channels, well vegetated alluvial and seasonally inundated islands, various types of

Liubov. V. Meshkova; Paul. A. Carling

2010-01-01

354

Landscape evolution, alluvial architecture, environmental history, and the archaeological record of the Upper Mississippi River Valley  

Microsoft Academic Search

The alluvial fill in the Upper Mississippi River Valley (UMV) is a palimpsest of past landscapes, environments, and physical evidence of human life ways. The valley has undergone significant changes in fluvial style during the time humans have occupied its landscapes, including changes in channel pattern, location of depocenters, and sediment lithology. Remnants of late-glacial braidplains that predate human presence

E. Arthur Bettis; David W. Benn; Edwin R. Hajic

2008-01-01

355

River bank filtration : spatial evolution with time of the reduced zone in a pumped alluvial aquifer  

Microsoft Academic Search

Biogeochemical processes occurring during the infiltration of river water into alluvial aquifers induce the development of a reduced zone due to the biodegradation of oxydizable dissolved components. Such geochemical conditions might be favorable or unfavorable to improvement of water quality, depending on the compounds. Choosing the location of a well in aquifer is therefore a key issue. To complicate things,

M. A. M. Kedziorek; A. C. M. Bourg; C. Crouzet

2003-01-01

356

Coseismic Hydrologic Response of an Alluvial fan to the 1999 Chi-Chi Earthquake, Taiwan  

Microsoft Academic Search

Alluvial fans along active mountain belts are often subjected to severe earthquake shaking that has led to some of the worst historical landslides even on very gentle slope. Despite the suggestion that these may have been caused by rising pore-pressure in sediment, direct evidence from systematic field measurements has been lacking. Widespread coseismic change in pore-water pressure occurred across a

Chi-Yuen Wang; Li-Hsin Cheng; Chi-Van Chin; Shui-Beih Yu

2001-01-01

357

Influence of Six Nitrification Inhibitors on Methane Production in a Flooded Alluvial Soil  

Microsoft Academic Search

The influence of six nitrification inhibitors (NI) on CH4 production in an alluvial soil under flooded condition was studied in a laboratory incubation experiment. The inhibition of CH4 production followed the order of sodium azide > dicyandiamide (DCD) > pyridine > aminopurine > ammonium thiosulfate > thiourea. Inhibition of CH4 production in DCD-amended soils was related to a high redox

K. Bharati; S. R. Mohanty; P. V. L. Padmavathi; V. R. Rao; T. K. Adhya

2000-01-01

358

NATURAL ARSENIC CONTAMINATION OF HOLOCENE ALLUVIAL AQUIFERS BY LINKED TECTONIC, WEATHERING, AND MICROBIAL PROCESSES  

EPA Science Inventory

Linked tectonic, geochemical, and biologic processes lead to natural arsenic contamination of groundwater in Holocene alluvial aquifers, which are the main threat to human health around the world. These groundwaters are commonly found a long distance from their ultimate source of...

359

Lindera melissifolia Seed Bank Study in a Lower Mississippi Alluvial Valley Bottomland Forest  

E-print Network

and the other half le on the soil surface. Additionally, bags contained seeds either with the oily fruit pulpLindera melissifolia Seed Bank Study in a Lower Mississippi Alluvial Valley Bottomland Forest K. Although L. melissifolia can annu- ally produce many bright red spicy scented drupes, information on repro

Fried, Jeremy S.

360

Investigating Source to Sink Processes with Cosmogenic 10Be Concentrations in Multiple Alluvial Grain Sizes  

Microsoft Academic Search

Recent studies suggest that concentrations of terrestrial cosmogenic nuclides (TCN) in varying grain sizes can provide important information about sediment source to sink pathways. However, some basic questions remain regarding the role that geomorphic processes play in determining TCN concentrations in alluvial sediment. As a result, there exists a critical need for an increased understanding of how sediment transport histories

T. L. Marstellar; K. L. Frankel; P. Belmont

2010-01-01

361

Using Geology to Improve Flood Hazard Management on Alluvial Fans -- an Example From Laughlin, Nevada  

Microsoft Academic Search

A study of the piedmont of the Newberry Mountains near Laughlin, Nevada, demonstrates that geologic information can improve the scientific basis of flood-hazard management on alluvial fans in desert areas. Comparison of geologic information against flood insurance rate maps (FIRMs) reveals flaws in conventional methods for flood hazard delineation in this setting. Geologic evidence indicates that large parts of the

P. Kyle House

2005-01-01

362

Spatio-temporal patterns of fish assemblages in a large regulated alluvial  

E-print Network

or to the nearest large woody debris. However, PLS regression revealed no significant differences in habitat of woody debris and lateral/longitudinal location. Eighteen fish species were sampled by electrofishingSpatio-temporal patterns of fish assemblages in a large regulated alluvial river. Freshwater

Paris-Sud XI, Université de

363

Arsenic enrichment in groundwater of the alluvial aquifers in Bangladesh: an overview  

Microsoft Academic Search

Arsenic in the groundwater of Bangladesh is a serious natural calamity and a public health hazard. Most groundwater from the shallow alluvial aquifers (<150 m), particularly in the Holocene plain lands, are vulnerable to As-enrichment. Delta plains and flood plains of the Ganges–Brahmaputra river system are moderately to severely enriched and more than 60% of the tube wells are affected.

K. Matin Ahmed; Prosun Bhattacharya; M. Aziz Hasan; S. Humayun Akhter; S. M. Mahbub Alam; M. A. Hossain Bhuyian; M. Badrul Imam; Aftab A Khan; Ondra Sracek

2004-01-01

364

Determine the optimum spectral reflectance of juniper and pistachio in arid and semi-arid region  

NASA Astrophysics Data System (ADS)

Arid and semi-arid areas of northeast Iran cover about 3.4 million ha are populated by two main tree species, the broadleaf Pistacia vera. L (pistachio) and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper). Natural stands of pistachio in Iran are not only environmentally important but genetically essential as seed sources for pistachio production in orchards. In this study, we estimated the optimum spectral reflectance of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. In this research spectral reflectance are able to specify of multispectral from Advanced Land Observing Satellite (ALOS) that provided by JAXA. These data included PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, has one band with a wavelength of 0.52-0.77 ?m and AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, has four multispectral bands: blue (0.42-0.50 ?m), green (0.52-0.60 ?m), red (0.61-0.69 ?m), and near infrared (0.76-0.89 ?m). Total ratio vegetation index (TRVI) of optimum spectral reflectance of juniper and pistachio have been evaluated. The result of TRVI for Pistachio and juniper were (R2= 0.71 and 0.55). I hope this research can provide decision of managers to helping sustainable management for arid and semi-arid regions in Iran.

Fadaei, Hadi; Suzuki, Rikie

2012-11-01

365

Alluvial records of late Quaternary environmental change along the eastern Andes  

NASA Astrophysics Data System (ADS)

The piedmont in eastern Bolivia and northwestern Argentina is built from a series of coalescent alluvial fans and constitutes the transition between the Andean mountains and their foreland. As these alluvial fans receive their sediments from small local catchments in the Subandean ranges, past geomorphic and environmental changes are potentially stored in their alluvial stratigraphic record. The paleosol-sediment-sequences contained in these fans generally exhibit marked shifts between morphological activity with sedimentation and/or erosion, and periods of soil formation. Here, we present data from two different locations in eastern Bolivia and northwestern Argentina, and interpret them with regard to late Quaternary geomorphic, environmental and paleoclimatic changes in central South America. New chronological data (14C, OSL) from the laterally extensive exposures at Cabezas (eastern Bolivia) are combined with detailed sedimentological documentation of these sequences, and indicate important changes in sediment supply and transport capacities at least since Marine Isotope Stage (MIS) 3. In northwestern Argentina at Riacho Seco, piedmont stratigraphy is exposed in a profoundly incised stream valley, providing insights into downstream variations of paleosols, sediments and alluvial fan architecture. Interpretation of these data is complemented by new isotopic data from soil organic matter which contributes to an improved understanding of regional late Quaternary paleoenvironments. The comparison of both sites shows surprising similarities over the last 20-30 ka, but points to substantial differences during MIS 3, providing hints to potential changes in larger-scale circulation patterns and moisture sources. In summary, alluvial records contain valuable and largely unexplored regional archives for future application of a variety of methods. This way the investigation of the piedmont along the eastern Andes in Bolivia and Argentina can provide further data necessary for an improved understanding of the complex interplay between geological, geomorphic and environmental controls on landscape evolution over different late Quaternary timescales.

May, J.; Preusser, F.; Veit, H.

2010-12-01

366

Some Cenozoic hydrocarbon basins on the continental shelf of Vietnam  

SciTech Connect

The formation of the East Vietnam Sea basins was related to different geodynamic processes. The pre-Oligocene basement consists of igneous, metamorphic, and metasediment complexes. The Cretaceous-Eocene basement formations are formed by convergence of continents after destruction of the Tethys Ocean. Many Jurassic-Eocene fractured magmatic highs of the Cuulong basin basement constitute important reservoirs that are producing good crude oil. The Paleocene-Eocene formations are characterized by intramountain metamolasses, sometimes interbedded volcanic rocks. Interior structures of the Tertiary basins connect with rifted branches of the widened East Vietnam Sea. Bacbo (Song Hong) basin is predominated by alluvial-rhythmic clastics in high-constructive deltas, which developed on the rifting and sagging structures of the continental branch. Petroleum plays are constituted from Type III source rocks, clastic reservoirs, and local caprocks. Cuulong basin represents sagging structures and is predominated by fine clastics, with tidal-lagoonal fine sandstone and shalestone in high-destructive deltas that are rich in Type II source rocks. The association of the pre-Cenozoic fractured basement reservoirs and the Oligocene-Miocene clastic reservoir sequences with the Oligocene source rocks and the good caprocks is frequently met in petroleum plays of this basin. Nan Conson basin was formed from complicated structures that are related to spreading of the oceanic branch. This basin is characterized by Oligocene epicontinental fine clastics and Miocene marine carbonates that are rich in Types I, II, and III organic matter. There are both pre-Cenozoic fractured basement reservoirs, Miocene buildup carbonate reservoir rocks and Oligocene-Miocene clastic reservoir sequences, in this basin. Pliocene-Quaternary sediments are sand and mud carbonates in the shelf facies of the East Vietnam Sea back-arc basin. Their great thickness provides good conditions for maturation and trapping.

Dien, P.T.

1994-07-01

367

The lithium, boron and strontium isotopic systematics of groundwaters from an arid aquifer system: Implications for recharge and weathering processes  

NASA Astrophysics Data System (ADS)

Saline groundwaters are common to inland Australia, but their hydrochemical evolution and origin remain largely unknown. The saline groundwaters in the alluvial aquifers of the Darling River have previously been found to exhibit broad similarity in traditional hydrochemical and isotopic tracers. By contrast, in this study the trace element isotopes (?7Li, ?11B and 87Sr/86Sr) have illuminated more complex hydrogeochemical processes in the same aquifer system. This paper reports the first ever set of ?7Li values in any groundwater system in Australia. They varied from +5.8 to +16.2 with an average value of +9.7‰ (n = 19) in the alluvial aquifers of the Darling River catchment. The ?11B values were all higher than seawater and close to some of the highest ?11B values ever reported in the literature for a groundwater system (+44.4 to +53.9; average: +48.8, n = 17). The 87Sr/86Sr ratios ranged from 0.708 to 0.713, with an average value of 0.709 (n = 19). The differing signatures in these trace element isotope values, highlighted by discovery of the deeper older groundwater system with heavier Li isotope values and higher 87Sr/86Sr, is an important finding of this research. Simple mixing models between river water and saline groundwater cannot explain the observed variation in trace element isotopes. Hydrochemical evolution was found to be dependent on proximity to the Darling River and depth. Varying degrees of Li and B isotopic fractionation during water-sediment interaction were interpreted to account for the evolution of the saline groundwaters. The measurement of these trace element isotopes has permitted delineation of groundwater end-members that would have otherwise not been identified; in their absence an inaccurate interpretation of the hydrochemical evolution of these saline groundwaters would have been made. This study highlights the importance of a multi-tracer approach, which includes trace element isotopes, in resolving complex geochemical processes in groundwater in semi-arid to arid zone environments.

Meredith, Karina; Moriguti, Takuya; Tomascak, Paul; Hollins, Suzanne; Nakamura, Eizo

2013-07-01

368

Development of an arid site closure plan  

SciTech Connect

This document describes the development of a prototype plan for the effective closure and stabilization of an arid low-level waste disposal site. This plan will provide demonstrated closure techniques for a trench in a disposal site at Los Alamos. The accuracy of modeling soil water storage by two hydrologic models, CREAMS and HELP, was tested by comparing simulation results with field measurements of soil moisture in eight experimental landfill cover systems having a range of well-defined soil profiles and vegetative covers. Regression analysis showed that CREAMS generally represented soil moisture more accurately than HELP simulations. Precautions for determining parameter values for model input and for interpreting simulation results are discussed. A specific example is presented showing how the field-validated hydrologic models can be used to develop a final prototype closure plan. 15 refs., 13 figs., 3 tabs.

Nyhan, J.W.; Barnes, F.J.

1987-01-01

369

PRESERVATION OF ARCHAEOLOGICAL MATERIALS IN ARID ENVIRONMENTS RELEVANT TO YUCCA MOUNTAIN  

SciTech Connect

The objective of this study was to evaluate archaeological materials from underground openings or shallow burial in arid environments relevant to Yucca Mountain and to draw conclusions about how their state and their environment of preservation could be of relevance to design and operational aspects of the high-level waste repository. The study has evaluated materials from cultures in the arid regions of the ancient Middle East and compared them with the preservation of ancient materials in dry cave sites in the Great Basin desert area of Nevada. The emphasis has been on materials found in undisturbed underground openings such as caves and un-backfilled tombs. Long-term preservation of such materials in underground openings and the stability of the openings themselves provide useful analogue information that serves as a reference point for considering the operation and evolution of the Yucca Mountain repository. Being able to shed light, by close physical and environmental analogy, on what happens in underground openings over many thousands of years provides valuable underpinning to illustrations of expected system performance and offers pointers towards optimizing repository system and operational design.

N. Chapman, A. Dansie, C. McCombie

2006-02-24

370

Holocene landscape evolution and geoarcheology of low-order streams in the Rio Grande basin, San Juan Mountains, Colorado, USA  

NASA Astrophysics Data System (ADS)

This geoarcheological study investigates soil stratigraphy and geochronology of alluvial deposits to determine Holocene landscape evolution within the Hot Creek, La Jara Creek, and Alamosa River drainage basins in the San Juan Mountains of Colorado. Geomorphic mapping and radiocarbon dating indicate synchronicity in patterns of erosion, deposition, and stability between drainage basins. In all three basins, the maximum age of mapped alluvial terraces and fans is ~ 3300 cal yr BP. A depositional period seen at both Hot Creek and the Alamosa River begins ~ 3300 to 3200 cal yr BP. Based on soil development, short periods of stability followed by alluvial fan aggradation occur in the Alamosa River basin ~ 2200 cal yr BP. A period of landscape stability at Hot Creek before ~ 1100 cal yr BP is followed by a period of rapid aggradation within all three drainages between ~ 1100 and 850 cal yr BP. A final aggradation event occurred between ~ 630 and 520 cal yr BP at La Jara Creek. These patterns of landscape evolution over the past ~ 3300 yr provide the framework for an archeological model that predicts the potential for buried and surficial cultural materials in the research area.

Carver, Daniel P.; Beeton, Jared M.

2014-09-01

371

Evaluation of Flow Dynamics in a Karst Aquifer System at Sapanca Lake Basin (turkey) via Hydrochemical and Isotopic Data  

NASA Astrophysics Data System (ADS)

Sapanca Lake, located 20 km west of Izmit bay, is a fresh water lake with tectonic origin and supplies drinking and municipal water to the region. Groundwater discharges from a karstic aquifer developed in Permo-Triassic and Late Jurassic-Early Cretaceous aged marbles and an alluvial aquifer distributed in east-west direction on the Sapanca plain play an important role in the recharge of the lake. In the Sapanca lake basin, there are numerous springs discharging (1 to 75 lt/s) from different elevations of the karstic aquifer system. Dolines, sinkholes, depression fields, and disappearing rivers developed on the southern heights of the basin are directly connected with the karstic aquifer and allow the aquifer system to show rapid recharge and discharge characteristics. In the scope of the study, 25 karst spring waters as well as 25 wells drilled in the alluvial aquifer were sampled as representatives of dry and rainy periods. Hydrochemical and isotopic (18O/2D/3H) compositions of the samples were evaluated along with the hydrogeology and the fracture analysis of the basin in order to assess the hydraulic relationship between the aquifer systems and the groundwater circulation in the basin. Results show that groundwaters from alluvial and karstic aquifers are modern water and demonstrate similar hydrochemical facies (Ca-HCO3 ve Ca+Mg-HCO3). Although showing seasonal differences, isotopic composition (18O/2D) of the karst springs resembles those of the streams and groundwaters from alluvial aquifer. This suggests that ground and surface waters feed each other periodically and characterize a mixing. Fracture analysis of the basin suggests that faulting has significant control over groundwater discharge and circulation in the karst aquifer and form discontinuities in the system, subdividing it into several aquifer sub-systems.

Gunduz, O. C.; Yolcubal, I.

2013-12-01

372

Estimates of mountain-front streamflow available for potential recharge to the Tularosa Basin, New Mexico  

USGS Publications Warehouse

Streamflow in the Tularosa Basin, New Mexico, infiltrates into alluvial-basin aquifers at or near mountain fronts. Streamflow at or near mountain fronts is a substantial component of potential recharge to these aquifers. Streamflow response from precipitation differs substantially between the streams draining the Sacramento Mountains on the eastern side of the basin and those draining the San Andres Mountains on the western side. Mean annual streamflow at mountain fronts that is available for potential recharge to the Tularosa Basin was estimated using two regional regression methods. The method for estimating mean annual streamflow using basin-climatic characteristics was applied to 46 subbasins in the Tularosa Basin. Drainage areas for the subbasins ranged from 0.87 to 157 square miles, and mean annual precipitation ranged from 11.80 to 24.89 inches. Mean annual streamflow to the basin is estimated to be about 95 cubic feet per second or 68,800 acre-feet using the basin-climatic characteristics method. The method for estimating mean annual streamflow using channel-geometry characteristics was applied to 12 subbasins in the Tularosa Basin. Of the 46 basins, 31 had drainage areas less than 20.7 square miles and 3 had active-channel widths less than 15 feet, which were outside the ranges used to develop the regression equations.

Waltemeyer, Scott D.

2001-01-01

373

Thermal influence on the groundwater fluid dynamics of the shallow Santiago forearc basin: 2D numerical simulations  

NASA Astrophysics Data System (ADS)

A thorough understanding of the thermal processes that occur in aquifers is essential to assess local and regional low enthalpy geothermal resources. The relationship between heat convection and heat conduction has been widely studied in basins around the world at a regional scale. However, few studies have focused on smaller, shallower basins containing free aquifers hosted in unconsolidated fluvial-alluvial sediments, like Santiago Basin. We use numerical modeling to simulate the fluid dynamics of the Santiago basin groundwater system under different thermal conditions. Despite the current computational advances, modeling such a complex system with a full 3D approach is still numerically time demanding and unstable. Besides, the basin has irregular geometry and variable hydraulic and thermal features. Thus, we performed a 2D model comprising a thin water saturated slice of sediments beneath the central part of the city, where the basin morphology is well constrained. We simulate coupled groundwater and heat flow throughout this vertical slice and we compare results for different scenarios that comprise different hydraulic, thermal and geometric parameters. Results obtained with certain hydraulic conductivities show that instabilities appear giving rise to free thermal convection in the deepest parts of the basin. If the system is split into several hydrogeological units, the onset of these instabilities is inhibited. Consequently, we suggest that the stratigraphic complexities of a fluvial-alluvial deposit should be considered to better understanding the thermal-driven groundwater fluid dynamics.

Gramusset, Anneli; Herrera, Paulo; Parada, Miguel Angel

2014-05-01

374

Reconstruction of Soil Moisture and Vegetation Water Use Conditions Based on Tree-Ring Widths From Qilian Juniper in Qaidam Basin, Northwestern China  

Microsoft Academic Search

Tree-ring widths have been used widely in studies of environmental changes and reconstructions of past climate. Eleven tree-ring chronologies of approximately 800-1500 years long were developed from Qilian juniper (Sabina przewalskii Kom.) for the eastern part of the Qaidam Basin, northwestern China. The study area is located in an arid\\/semi-arid region with desert and dry grassland vegetation, but sparse juniper

Z. Yin; X. Shao; E. Liang; N. Qin

2005-01-01

375

Spatial variability of soil apparent electrical conductivity(ECa) and the water table depth in an alluvial valley under different uses.  

NASA Astrophysics Data System (ADS)

The apparent soil electrical conductivity (ECa), measured by contact or by electromagnetic induction (EMI), has been widely used as a variable that is correlated with physical and chemical soil properties. Therefore this property is used as a parameter in precision agriculture, to enable assessment of soil spatial variability and defining management units, allowing obtaining information about other soil properties like texture, salinity, water content, among others. These conditions are adequate to study spatial variability of data with the help of geostatistics, which models the spatial variability of soil properties, allowing the construction of spatial variability maps unbiased and with minimum variance. Thus, the goal this work was assess the variability special of electrical conductivity apparent soil (ECa) and the water table level in an alluvial valley in the brazilian semi-arid adopting different uses. The studied alluvial valley is located in Pesqueira (Pernambuco State, Brazil) and has 421.0 hectares. The main soil types occurring in the valley are: Fluvic Neosols , litholic Neossols and regolithic Neosols . Climate according to Koppen's classification is BSsh type, with total annual rainfall average of 730mm. The attributes evaluated in this study were sampled at 88 piezometric wells. The apparent soil electrical conductivity (ECa) was measured by electromagnetic induction with the EM38 device (Geonics Ltd) in vertical dipole (effective depth 1.5m). The ground water table was determined in piezometric wells with the aid of a measuring tape. Data were analyzed by using descriptive statistics and geostatistical tools. The land use map was constructed using field verification and spatialized by means of GIS. The attributes analyzed showed Normal frequency distribution. ECa readings ranged between 8 and 79 mS m-1. The major differences between the ECa values are due to the variation of water content in soil and distance from the water table at the soil surface. The water table in the study area ranged from 0.8 to 3.8 m deep. The Pearson linear correlation found for the data in the study was zero (r = -0.0185). The Gaussian model was the best fit to the data, and the water table had the highest range value (a = 500.00 m). The maps of spatial variability of water table and ECa have similar spatial behavior, indicating that where the water table is deeper at places with the lowest ECa.

Siqueira, G. M.; Fontes Júnior, R. V. P.; Montenegro, A. A. A.; Barros, Y. L.; Silva, E. F. F.

2012-04-01

376

Late Tertiary and Quaternary geology of the Tecopa basin, southeastern California  

SciTech Connect

Stratigraphic units in the Tecopa basin, located in southeastern California, provide a framework for interpreting Quaternary climatic change and tectonism along the present Amargosa River. During the late Pliocene and early Pleistocene, a climate that was appreciably wetter than today`s sustained a moderately deep lake in the Tecopa basin. Deposits associated with Lake Tecopa consists of lacustrine mudstone, conglomerate, volcanic ash, and shoreline accumulations of tufa. Age control within the lake deposits is provided by air-fall tephra that are correlated with two ash falls from the Yellowstone caldera and one from the Long Valley caldera. Lake Tecopa occupied a closed basin during the latter part, if not all, of its 2.5-million-year history. Sometime after 0.5 m.y. ago, the lake developed an outlet across Tertiary fanglomerates of the China Ranch Beds leading to the development of a deep canyon at the south end of the basin and establishing a hydrologic link between the northern Amargosa basins and Death Valley. After a period of rapid erosion, the remaining lake beds were covered by alluvial fans that coalesced to form a pediment in the central part of the basin. Holocene deposits consist of unconsolidated sand and gravel in the Amargosa River bed and its deeply incised tributaries, a small playa near Tecopa, alluvial fans without pavements, and small sand dunes. The pavement-capped fan remnants and the Holocene deposits are not faulted or tilted significantly, although basins to the west, such as Death Valley, were tectonically active during the Quaternary. Subsidence of the western basins strongly influenced late Quaternary rates of deposition and erosion in the Tecopa basin.

Hillhouse, J.W.

1987-12-31