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1

Spatio-temporal recharge patterns in a semi-arid alluvial basin with irrigated crops  

NASA Astrophysics Data System (ADS)

Recharge in semi-arid regions with irrigated crops is predominantly driven by irrigation technology and cropping patterns, but also by the seasonal distribution of rainfall and the availability of irrigation water. A significant amount of basin recharge occurs from ephemeral streams and unlined irrigation canals. A spatially distributed, GIS-based hydrologic model of water application and water use at the land-atmosphere interface was developed to estimate transient recharge to the deep vadose zone and into the unconfined alluvial aquifer. The spatial basis for the hydrologic model are individual landuse units (diffuse recharge) and a network of streams and canals with water seepage (lineal recharge). The land-atmosphere interface and unsaturated zone model component (LAIUZ) is coupled to a surface water supply model component (SWSM) that provides surface water deliveries by district or sub-district, depending on available information. Using LAIUZ and SWSM, we investigate the regional behavior and spatio-temporal variability of deep vadose zone recharge in the 3,800 square kilometer Tule groundwater basin of the San Joaquin Valley, California. Surface water management in the topographically flat basin is divided between two dozen irrigation and water districts. All surface water is imported or is natural discharge into the basin. Groundwater extractions are managed by landowners on a field-by-field basis. Monthly varying recharge and groundwater pumping rates are computed for the hydrologic years 1970 through 2000. The average size of the GIS landuse units is 0.4 sq. kilometers. The GIS coverage distinguishes over 60 landuse types. Applied and consumptive water use are computed based on actual evapotranspiration and known irrigation or water use efficiencies for each landuse unit. Seepage from streams is computed by mass balance. The resulting model estimates of groundwater recharge and pumping are in good agreement with measured groundwater level changes for the thirty-year period (model validation). Throughout the region, the deep vadose zone (up to 30 m deep) is found to account for a significant amount of intermediate-term basin storage, particularly during wet year cycles. The hydrologic model demonstrates that practically all of the annual precipitation (230 mm) is available for intermediate storage in the root zone, crop water uptake, or deep percolation. No direct losses to evaporation occur, presumably because most precipitation occurs during the winter months. Diffuse recharge is 110 mm/year (range: 38 - 200 mm/year). Lineal recharge accounts for one-third of the total recharge (170 mm/year) in the basin. In wet years, lineal recharge along streams and in intentional recharge basins may account for over 50% of the total recharge, whereas in dry years it may be as little as 8%.

Ruud, N. C.; Harter, T.; Naugle, A. W.

2001-12-01

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

Geomorphology-based index for detecting minimal flood stages in arid alluvial streams  

NASA Astrophysics Data System (ADS)

Identification of a geomorphic index to represent lower thresholds for minor flows in ephemeral, alluvial streams in arid environments is an essential step in reliable flash flood hazard estimations and establishing flood warning systems. An index, termed Alluvial wadi Flood Incipient Geomorphologic Index (AFIG), is presented. Analysis of data from an extensive field survey in the arid ephemeral streams in Southern and Eastern Israel was conducted to investigate the AFIG and the control over its value across the region. During the survey we identified distinguishable flow marks in the lower parts of streams' banks, such as niches, vegetation line, and change in bank material, which are indicative of low flows. The cross-sectional characteristics of the AFIG were studied in relationship with contributing drainage basin characteristics such as lithology, topography, and precipitation. Drainage area and hardness of the exposed lithology (presented as a basin-wide index) are the preferred descriptors to be used in estimating a specific AFIG in un-surveyed sites. Analyses of discharge records from seven hydrometric stations indicate that the recurrence interval of the determined AFIG is equal to or more frequent than 0.5 yr.

Shamir, E.; Ben-Moshe, L.; Ronen, A.; Grodek, T.; Enzel, Y.; Georgakakos, K.; Morin, E.

2012-11-01

4

Geomorphology-based index for detecting minimal flood stages in arid alluvial streams  

NASA Astrophysics Data System (ADS)

Identification of a geomorphic index to represent lower thresholds for minor flows in ephemeral, alluvial streams in arid environments is an essential step as a precursor for reliable flash flood hazard estimations and establishing flood warning systems. An index, termed Alluvial wadi Flood Incipient Geomorphologic Index (AFIG), is presented. Analysis of data from an extensive field survey in the arid ephemeral streams in southern and eastern Israel was conducted to investigate the AFIG and the control over its value across the region. During the survey we identified distinguishable flow marks in the lower parts of streams' banks, such as niches, vegetation line, and change in bank material, which are indicative of low flows. The cross-sectional characteristics of the AFIG were studied in relationship with contributing drainage basin characteristics such as lithology, topography, and precipitation. Drainage area and hardness of the exposed lithology (presented as a basin-wide index) are the preferred descriptors to be used in estimating a specific AFIG in unsurveyed sites. Analyses of discharge records from seven hydrometric stations indicate that the recurrence interval of the determined AFIG is equal to or more frequent than 0.5 yr.

Shamir, E.; Ben-Moshe, L.; Ronen, A.; Grodek, T.; Enzel, Y.; Georgakakos, K. P.; Morin, E.

2013-03-01

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  

Microsoft Academic Search

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

Lewis A. Owen; Robert C. Finkel; M. Haizhou; Patrick L. Barnard

2006-01-01

6

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

7

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

USGS Publications Warehouse

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 width increasing, and coverage of aquatic macrophytes expanding. Average stream velocity at Pinal Creek decreased from 0.8 to 0.2 m/s, average stream depth decreased from 0.09 to 0.04 m, and average channel width expanded from 3 to 13 m. Modeling of tracer experiments indicated that the hydrologic retention factor (Rh), a measure of the average time that solute spends in storage per unit length of downstream transport, increased from 0.02 to 8 s/m. At the same time the ratio of cross-sectional area of storage zones to main channel cross-sectional area (As/A) increased from 0.2 to 0.8 m2/m2, and average water residence time in storage zones (ts) increased from 5 to 24 min. Compared with published data from four other streams in the US, Pinal Creek experienced the greatest change in hydrologic retention for a given change in streamflow. The other streams differed from Pinal Creek in that they experienced a change in streamflow between tracer experiments without substantial geomorphic or vegetative adjustments. As a result, a regression of hydrologic retention on streamflow developed for the other streams underpredicted the measured increases in hydrologic retention at Pinal Creek. The increase in hydrologic retention at Pinal Creek was more accurately predicted when measurements of the Darcy-Weisbach friction factor were used (either alone or in addition to streamflow) as a predictor variable. We conclude that relatively simple measurements of channel friction are useful for predicting the response of hydrologic retention in streams to major adjustments in channel morphology as well as changes in streamflow. Published by Elsevier Ltd.

Harvey, J. W.; Conklin, M. H.; Koelsch, R. S.

2003-01-01

8

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

9

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

Microsoft Academic Search

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

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

2010-01-01

10

Alluvial sinkholes over gypsum in the Ebro basin (Spain): genesis and environmental impact  

Microsoft Academic Search

The Ebro Basin is located in the northeast of Spain. Its central part is filled with gypsum and carbonate deposits of Neogene age. Quaternary sediments overlie the Tertiary layers. Alluvial sinkholes have developed in this region, causing high economic losses. From the study of aerial photographs, from the compilation of historical cases of collapse and from data on the lithological

M. A. SORIANO; J. L. SIMON; J. GRACIA; T. SALVADOR

11

Orbital forcing in the early Miocene alluvial sediments of the western Ebro Basin, Northeast Spain  

NASA Astrophysics Data System (ADS)

Paleoclimatic reconstructions from terrestrial records are crucial to assess the regional variability of past climates. Despite the apparent direct connection between continental sedimentary environments and climate, interpreting the climatic signature in ancient non-marine sedimentary sequences is often overprinted by source-area related signals. In this regard, foreland basins appear as non-ideal targets as tectonically-driven subsidence and uplift play a major control on the distribution and evolution of sedimentary environments and facies. Foreland basins, however, often yield among the thickest and most continuous stratigraphic records available on continents. The Ebro Basin (north-eastern Spain) is of particular interest among the circum-mediterranean alpine foreland basins because it evolved into a land-locked closed basin since the late Eocene, leading to the accumulation of an exceptionally thick (>5500 m) and continuous sequence of alluvial-lacustrine sediments over a period of about 25 Myr. In this paper we present a detailed cyclostratigraphic study of a 115 m thick section in the Bardenas Reales de Navarra region (western Ebro Basin) in order to test orbital forcing in the Milankovitch frequency band. The study section corresponds to the distal alluvial-playa mud flats which developed in the central sector of the western Ebro Basin, with sediments sourced from both the Pyrenean and Iberian Ranges. Sediments consist of brown-red alluvial clay packages containing minor fine-grained laminated sandstones sheet-beds and channels, grey marls and thin bedded lacustrine limestones arranged in 10 to 20 m thick fining-upwards sequences. Red clayed intervals contain abundant nodular gypsum interpreted as representing a phase of arid and low lake level conditions, while grey marls and limestones indicate wetter intervals recording the expansion of the inner shallow lakes. A magnetostratigraphy-based chronology indicates that the Peñarroya section represents a time interval of about 500 kyr centered around chron C6r, although inferred absolute ages diverge depending on the assumed calibration of geomagnetic reversals with the astronomical time scale (Billups et al., 2004, Lourens et al., 2004). The section was sampled with a portable drill at regular intervals of about 30 cms, representing a time resolution of near 1 kyr. Spectral analysis of different measured parameters (lithology code, color, magnetic susceptibility and other rock magnetic parameters) revealed significant power at 20.4 m, 9.6 m and 4.2 m, which correspond to a ratio of 1:2.1:4.9 similar to that given by the Milankovitch cycles of eccentricity, obliquity and precession. Maximum power in the spetrum is focused in the eccentricity and obliquity bands while signal corresponding to precession is weakly expressed. The existing uncertainties in the astronomical tuning of the Early Miocene geomagnetic polarity time scale prevents us from using magnetostratigraphy to anchor the Peñarroya record with the astronomical solutions (Laskar et al., 2004). Instead, we have tried the expression of the eccentricity cycle to tune the Peñarroya section. We correlated the thick red clayed (dry phase) intervals with eccentricity minima, a phase relationship which is in agreement with that derived from earlier studies in marine and continental records from the Miocene of the Iberian plate (Abels et al., 2008, Sierro et al., 2000). The resulting tuning of the Peñarroya section yields an age for the base of geomagnetic chron C6r which fits with earlier work of Billups et al., (2004), while the top of C6r gives a significantly younger age. References Abels, H., Abdul Aziz, A., Calvo, J.P. and Tuenter, E., 2008. Shallow lacustrine carbonate microfacies document orbitally paced lake-level history in the Miocene Teruel Basin (North-East Spain), Sedimentology doi: 10.1111/j.1365-3091.2008.00976.x. Billups, K., Pälike, H., Channell, J.E.T., Zachos, J. and Shackleton, N.J., 2004. Astronomic calibration of the late Oligocene through early Miocene geomagnetic polarity time sca

Garces, M.; Larrasoaña, J. C.; Muñoz, A.; Margalef, O.; Murelaga, X.

2009-04-01

12

Occurrence of saltwater in the alluvial aquifer in the Boeuf-Tensas Basin, Arkansas  

USGS Publications Warehouse

The occurrence of saline water in the alluvial aquifer in the Boeuf-Tensas basin in southeastern Arkansas has been of increasing concern. A band of saline water containing chloride concentrations of greater than 50 milligrams per liter extends through the entire length of the basin. The most severely affected area is located in the southern part of the basin where chloride concentrations are as high as 1,360 milligrams per liter. The origin of the saline water in the alluvial aquifer is not definitely known, but can probably be attributed at least in part, to both upward movement from the Arkansas River. Upward instrusion of saline ground water has probably occurred through one or more of the following: 1) leakage where the Jackson confining unit is thinned or absent, 2) leakage along a fault, and 3) movement through abandoned oil and gas test holes. (USGS)

Fitzpatrick, D. J.

1985-01-01

13

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

14

Overlapping of pedogenesis and meteoric diagenesis in distal alluvial and shallow lacustrine deposits in the Madrid Miocene Basin, Spain  

NASA Astrophysics Data System (ADS)

The Miocene distal alluvial fan and palustrine deposits of the Madrid Basin (Paracuellos de Jarama area) were examined to establish the sequence of its pedogenic-diagenetic processes and the main factors controlling them. In this area the diagenetic processes operated not only on carbonates, as commonly studied, but also in high magnesium clays and opaline cherts. This paper provides a dynamic model for saline-alkaline lake margins that complements the existing freshwater palustrine model. Three sections (BER, PEL and UPC) containing limestones, sepiolite, dolostones and opaline cherts were examined; these represent the entire transition from alluvial fan deposit to lake environment. The alluvial fan deposits (PEL section) show the most complex sequence of processes. After a weak edaphic imprint, the primary mudstone and siltstones are affected by silicification (opaline levels formed mainly by selective replacement of sepiolites) and later dolomitization. Several types of dolomite are present, rounded crystals, spherules and globular bodies being the most characteristic. In the ponds situated at the foot of the alluvial fans or in interfan areas, sepiolite precipitated within free water bodies (BER section) and an intense pedogenesis led to the formation of palustrine sepiolite deposits. Later, the intense silicification of the sepiolite produced lenticular opaline levels that were locally transformed to quartz by aging. In the shallow lakes (UPC section), palustrine limestones and sepiolite were deposited. The carbonates are partially affected by silicification, the sepiolite becoming completely silicified. The opaline levels clearly preserve the structure of the limestones and sepiolite host rocks. All the opaline levels show local aging processes. The silicification processes were different in the three settings due to the interplay of groundwater with sedimentary environments and facies. In the distal alluvial fan sediments of the PEL section, the initial host rock affected by silicification is not preserved due to the later dolomitization that erased both it and its textures. The silicification environment was therefore not easy to determine. In the BER and UPC section, the main silicification took place in groundwater-influenced environments but evidence was seen of cements and silicifications in vadose environments. In all study settings, the overlapping of pedogenic, vadose and groundwater processes was controlled by changes in the position of the water table. Four stages were concluded to explain the transformation from the primary deposits to the later dolomitization process and the formation of vadose cements. The majority of the silicifications seen occurred as responses to changes in the water table position linked to the aggradation of this closed basin. In all the studied environments, the sepiolite deposits were preferentially silicified; their fibrous structure and high absorption capacity helping to retain interstitial fluids. Moreover sepiolite and opal are stable under relatively similar geochemical conditions in arid environments. The dissolution of the sepiolite caused an increase in silica in the interstitial fluids, favouring silicification and ruling out the need of a biogenic source. The replacement of limestones by silica is usually driven by variations in pH and salinity, which are very common in surface environments such as shallow lakes and soils.

Bustillo, M. a.. A.; Alonso-Zarza, A. M. a..

2007-06-01

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

Planning report for the southwest alluvial basins (east) regional aquifer-system analysis, parts of Colorado, New Mexico, and Texas  

USGS Publications Warehouse

The study of the Southwest alluvial basins (east) will involve an analysis of the regional aquifer system in parts of Colorado, New Mexico, and Texas. This area has been divided into 22 basins. The study of the alluvial aquifer-system will be made in the following stages: (1) project planning, (2) literature searches, (3) compiling existing data, (4) data collection, (5) basin modeling, (6) regional aquifer modeling, and (7) reports. The regional aquifer study will be accomplished through studying each of the 22 basins. Data compilation and limited data collection will be part of each basin study. Digital computer models will be made for those basins where data are sufficient. A regional aquifer model will be developed from the basin models. In addition to this report, there will be basin hydrology reports and the final regional report. Included in the final report will be a description of the regional hydrology and geology. (USGS)

Wilkins, D. W.; Scott, W. B.; Kaehler, C. A.

1980-01-01

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

Ground-water quality in alluvial aquifers in the eastern Iowa basins, Iowa and Minnesota  

USGS Publications Warehouse

The quality of shallow alluvial ground water that is used for domestic supplies in the Wapsipinicon, Cedar, Iowa, and Skunk River Basins (Eastern Iowa Basins) is described. Water samples from 32 domestic-supply wells were collected from June through July 1998. This study of ground-water quality in alluvial aquifers in the Eastern Iowa Basins is part of the U.S. Geological Survey's National Water-Quality Assessment Program. Calcium and bicarbonate were the dominant ions in solution, likely derived from the dissolution of carbonate minerals in the alluvial aquifer material. Concentrations of iron exceeded the U.S. Environmental Protection Agency Secondary Maximum Contaminant Level (300 micrograms per liter) for drinking water in 53 percent of the samples, and 50 percent of the samples exceeded the Secondary Maximum Contaminant Level for manganese (50 micrograms per liter). pH and alkalinity increased and sulfate concentrations decreased with increasing well depth. Nitrite plus nitrate nitrogen was detected in 53 percent of the samples and exceeded the U.S. Environmental Protection Agency Maximum Contaminant Level of 10 milligrams per liter for drinking water in 13 percent of the samples. Nitrite plus nitrate nitrogen concentrations were negatively correlated with well depth and positively correlated with percentage of oxygen saturation. Ammonia plus organic nitrogen concentrations were positively correlated with well depth, and ratios of nitrite plus nitrate to ammonia were positively correlated with percentage of oxygen saturation. The majority of samples, 72 percent, contained water recharged since the early 1950's. The recharge date of water was earlier in deeper wells. Nitrite plus nitrate and total pesticide concentrations were greater in more recently recharged water. Eight pesticides and eight pesticide metabolites were detected in ground-water samples. Atrazine was the most commonly detected pesticide, and metolachlor ethanesulfonic acid was the most commonly detected metabolite. No pesticide detections exceeded U.S. Environmental Protection Agency drinking-water Maximum Contaminant Levels. The effects of land use on ground-water quality also were examined. There was a positive correlation between percentage of land used for soybean production and concentrations of metolachlor, metolachlor ethanesulfonic acid, and metolachlor oxanilic acid in ground-water samples. Data from this study and from previous studies in the Eastern Iowa Basins were compared statistically by well type (domestic, municipal, and monitoring wells). Well depths were significantly greater in domestic and municipal wells than in monitoring wells. pH, calcium, sulfate, chloride, and atrazine concentrations were significantly higher in municipal-well samples than in domestic-well samples. pH and sulfate concentrations were significantly higher in municipal-well samples than in monitoring-well samples. Ammonia was significantly higher in domestic-well samples than in monitoring-well samples, chloride was significantly higher in monitoring-well samples than in domestic-well samples, and fluoride was significantly higher in domestic-well samples than in municipal-well samples.

Sadorf, Eric M.; Linhart, S. Michael

2000-01-01

21

Alluvial aquifer of the Cache and St. Francis River basins, northeastern Arkansas  

USGS Publications Warehouse

The alluvial aquifer underlies about 9,000 square miles of the study area. Well yields from the aquifer commonly are from 1,000 to 2,000 gallons per minute. Flow toward the main area of pumping stress is eastward from the Cache River and westward from the St. Francis River. The Memphis aquifer acts as a conduit through Crowleys Ridge for induced flow from the St. Francis River basin to the Cache River basn. Water use from the alluvial aquifer since the early 1900 's has been mostly for rice irrigation. Total pumpage for rice in 1978 was about 1,650 ,000 acre-feet, of which about 88 percent was pumped from the aquifer west of Crowleys Ridge. Water levels in wells west of the ridge in parts of Poinsett, Cross, and Craighead Counties in 1978 were 75 feet below land surface and declining about 2 feet per year. Digital-model analysis indicated that at the end of 1978 water was being removed from aquifer storage at the rate of 540,000 acre-feet per year, and streamflow, mostly from the Cache River and Bayou DeView, was being captured at the rate of 430,000 acre-feet per year. Projecting the 1978 pumping rate of 1,460,000 acre-feet per year, the pumping rate would have to be reduced by about 110,000 acre-feet per year by 1990 to sustain sufficient aquifer saturation for water needs through the year 2000 in all parts of Poinsett, Craighead, and Cross Counties west of Crowleys Ridge. (USGS)

Broom, Matthew E.; Lyford, Forest P.

1981-01-01

22

Analysis of the Carmel Valley alluvial ground-water basin, Monterey County, California  

USGS Publications Warehouse

A two-dimensional, finite-element, digital model was developed for the Carmel Valley alluvial ground-water basin using measured, computed, and estimated discharge and recharge data for the basin. Discharge data included evapotranspiration by phreatophytes and agricultural, municipal, and domestic pumpage. Recharge data included river leakage, tributary runoff, and pumping return flow. Recharge from subsurface boundary flow and rainfall infiltration was assumed to be insignificant. From 1974 through 1978, the annual pumping rate ranged from 5,900 to 9,100 acre-feet per year with 55 percent allotted to municipal use principally exported out of the valley, 44 percent to agricultural use, and 1 percent to domestic use. The pumpage return flow within the valley ranged from 900 to 1,500 acre-feet per year. The aquifer properties of transmissivity (about 5,900 feet squared per day) and of the storage coefficient (0.19) were estimated from an average alluvial thickness of 75 feet and from less well-defined data on specific capacity and grain-size distribution. During calibration the values estimated for hydraulic conductivity and storage coefficient for the lower valley were reduced because of the smaller grain size there. The river characteristics were based on field and laboratory analyses of hydraulic conductivity and on altitude survey data. The model is intended principally for simulation of flow conditions using monthly time steps. Time variations in transmissivity and short-term, highrecharge potential are included in the model. The years 1974 through 1978 (including "pre-" and "post-" drought) were selected because of the extreme fluctuation in water levels between the low levels measured during dry years and the above-normal water levels measured during the preceding and following wet years. Also, during this time more hydrologic information was available. Significantly, computed water levels were generally within a few feet of the measured levels, and computed flows were close to gaged riverflows for this simulation. However, the nonuniqueness of solutions with respect to different sets of data indicates the model does not necessarily validate the correctness of the individual variables. The model might be improved with additional knowledge of the distribution of confining sediments in the lower end of the valley and the aquifer properties above and below them. The solution algorithm could account for confinement or partial confinement in the lower end of the valley plus contributions from the Tularcitos aquifer.

Kapple, Glenn W.; Mitten, Hugh T.; Durbin, Timothy J.; Johnson, Michael J.

1984-01-01

23

Flood delineation in a large and complex alluvial valley, lower Panuco basin, Mexico  

NASA Astrophysics Data System (ADS)

Determining the extent of flooding is an important role of the hydrological research community and provides a vital service to planners and engineers. For large river systems located within distant settings it is practical to utilize a remote sensing approach. This study delineates the extent of a large flood event in the lower Panuco basin, the seventh largest (98,227 km^2) river system draining into the Gulf of Mexico. The lower Panuco basin is located within the coastal plain of east-central Mexico and has a complex alluvial valley. Data sources included a Landsat 5TM and Landsat 7ETM^+ scene, and topographic and particle size data from fieldwork and laboratory analysis. The Landsat 5TM scene was acquired after the peak of a large flood event in 1993, whereas the Landsat 7ETM^+ scene was acquired during the dry season in 2000. The increasing number of days between flood crest and image acquisition along the river valley provided the opportunity to examine several methods of flood delineation, and consider differences in floodplain environments. Backswamp environments were easily delineated in flooded reaches within the lower Panuco and Tamuin valleys, whereas in the Moctezuma valley more sophisticated methods were required because of the greater time between image acquisition and flood peak, and the complex floodplain topography. This included principal components analysis, as well as image merge (Landsat 5TM and Landsat 7ETM^+) and image classification. Floodplain environments that were topographically higher and had coarser sediments, such as natural levees, often were not classified as flooded because of their rapid rate of drainage upon recession of the flood crest. Within the floodplain, residual Holocene terraces may also complicate flood mapping. Image classification of merged images (Landsat 5TM and Landsat 7ETM^+) allowed the influence of permanent standing water to be considered. Although the flooded areas were greater in the lower reaches of the study area, because this portion of the valley contained large floodplain lakes, the amount of inundation was actually lower. Remote sensing offers the ability to examine large alluvial valleys in distant settings. However, utilizing a remote sensing approach does not imply that geomorphic criteria should be excluded. Indeed, because of heterogeneous floodplain topography this study illustrates the importance of including limited field based geomorphic analysis so that the complexity of distinct floodplain environments can be considered. The findings from this study are significant because most remote sensing data obtained for the purpose of flood mapping will not coincide with the flood crest. Thus, this study provides an appropriate method for mapping flood inundation after the flood crest in large and complex floodplain settings.

Colditz, R.; Hudson, P.

2003-04-01

24

Flood delineation in a large and complex alluvial valley, lower Pa´nuco basin, Mexico  

NASA Astrophysics Data System (ADS)

Determining the extent of flooding is an important role of the hydrological research community and provides a vital service to planners and engineers. For large river systems located within distant settings it is practical to utilize a remote sensing approach. This study combines a remote sensing and geomorphic approach to delineate the extent of a large hurricane generated flood event in the lower Pánuco basin (98,227 km 2), the seventh largest river system draining into the Gulf of Mexico. The lower Pánuco basin is located within the coastal plain of eastern Mexico and has a complex alluvial valley. Data sources included a Landsat 5TM and Landsat 7ETM + scene, and topographic and particle size data from fieldwork and laboratory analysis. The Landsat 5TM image was acquired after the peak of a large flood event in 1993, whereas the Landsat 7ETM + scene was acquired during the dry season in 2000. The increasing number of days between flood crest and the date of flood image acquisition along the river valley provided the opportunity to examine several methods of flood delineation and to consider differences in floodplain geomorphology. Backswamp environments were easily delineated in flooded reaches within the Panuco and Tamuin valleys, whereas in the Moctezuma valley more sophisticated methods were required because of the greater time between image acquisition and flood peak, and the complex floodplain topography. This included Principal Component (PC) analysis and image classification. Within the floodplain, residual Holocene terraces complicated flood mapping. Classification of both images allowed consideration of the influence of permanent standing water. Although the flooded areas were greater in the lower reaches of the study area, because this portion of the valley contained large floodplain lakes, the amount of inundation was actually lower. Remote sensing offers the ability to examine large alluvial valleys in distant settings but does not imply that geomorphic criteria should be excluded. Indeed, because of heterogeneous floodplain topography this study illustrates the importance of including field based geomorphic analysis so that the complexity of distinct floodplain environments are considered. The findings from this study are significant because most remote sensing data obtained for the purpose of flood mapping will not coincide with the flood crest. Thus, this study provides an appropriate method for mapping flood inundation in large and complex floodplain settings after flood crest recession.

Hudson, Paul F.; Colditz, René R.

2003-09-01

25

Palaeohydrological and palaeoecological studies on South Cameroonian alluvial sedimentary basins - New evidence on the palaeoenvironmental evolution of western Central Africa since the Late Pleistocene  

NASA Astrophysics Data System (ADS)

A new valuable and innovative contribution will be presented to ascertain the timing and extension of climatic and ecological changes in western equatorial Africa. Main focus is laid on the dynamics of climate, fluvial systems and the high sensitive tropical ecosystems (dense evergreen and semi-deciduous rain forest and savanna-rain forest margin) since the Late Pleistocene (~50 kyrs. BP). For this purpose extended fieldworks were carried out in South Cameroon (2004-2008) by the ReSaKo-Project (sub-project of DFG-Project 510) with abundant investigations on alluvial sedimentary basins of equatorial tropical fluvial systems. Suitable alluvial sediment-archives for palaeoenvironmental research were uncovered along selected braiding, meandering and anabranching/anastomosing reaches of major southwestern, into the Gulf of Guinea (Ntem, Nyong and Sanaga) and southeastern, into the Congo basin (Boumba, Dja and Ngoko) draining rivers (RUNGE et al. 2006, SANGEN 2008). Among geomorphological investigations and cross section discussions, 150 corings (Edelman, 20 cm layers) reaching maximum depths of 550 cm were carried out on river benches, levees, cut-off and periodical branches, islands and terraces as well as in seasonal inundated floodplains and backswamps. Corresponding sedimentary profiles and catenae recovered multilayered, sandy to clayey alluvia containing sedimentary form-units and palaeosurfaces which contribute to the reconstruction of palaeoenvironmental conditions in western equatorial Africa. Several (59) radiocarbon (AMS) dated samples (Erlangen and Lecce) from fossil organic layers and macro-rests embedded in these units yielded Late Pleistocene to recent ages (14C-ages around 48 to 0.2 kyrs. BP), spanning also the Last Glacial Maximum (LGM) and Holocene record. Abrupt grain-size modifications and alternating form-units (sandy and clayey layers, palaeosurfaces) in the stratigraphic records display fluctuations in the fluvial-morphological response of the fluvial systems to climatic variability and other extrinsic and intrinsic impacts. Although the sedimentary record varies among the studied river reaches, fossil organic sediment layers (palaeosurfaces) containing valuable proxy data were found in almost all alluvia basins of examined southern Cameroonian rivers. Around 56 ^13C-values corresponding to the dated samples (-31.4 to -18.0 ) evidence that despite major disturbances of the African rain forest over geological times (MALEY 2001) mainly rain forest ecosystems have prevailed during the corresponding time periods, presumably as gallery forests, which were able to persist in this fluvial habitat ("fluvial refuge"), even during arid periods (e.g. LGM). The results are consistent with earlier findings from lacustrine (SERVANT & SERVANT-VILDARY 2000), marine (WELDEAB et al. 2007) and additional sediment archives (GASSE et al. 2008) and will add additional insights and information to the unravelling of the complex respond of the African monsoon, the Central African ecosystems and fluvial systems to Late Quaternary climatic and environmental fluctuations within a globally teleconnected system. References: GASSE, F., CHALIé, F., VINCENS, A., WILLIAMS, M.A.J. & WILLIAMSON, D. (2008): Climatic patterns in equatorial and southern Africa from 30,000 to 10,000 years ago reconstructed from terrestrial and near-shore proxy data. Quaternary Science Reviews, 27 (25-26), 2316-2340. MALEY, J. (2001): The impact of arid phases on the African rain forest through geological history. In: WEBER, W., WHITE, L., VEDDER, A., NAUGHTON-TREVES, L. (Eds.): African rain forest ecology and conservation - An interdisciplinary perspective. Yale University Press, New Haven, 68-87. RUNGE, J., EISENBERG, J., SANGEN, M. (2006): Geomorphic evolution of the Ntem alluvial basin and physiogeographic evidence for Holocene environmental changes in the rain forest of SW Cameroon (Central Africa) - preliminary results. Z. Geomorph. N.F., Suppl. Bd. 145, 63-79. SERVANT, M. & SERVANT-VILDARY, S. (2000): Dynamique à long terme des

Sangen, M.

2009-04-01

26

Sinkhole Evolution in Alluvial Deposits within the Central Ebro Basin, Northeast Spain  

Microsoft Academic Search

We have used aerial photo analysis and geophysical data to study the evolution of sinkholes developed on alluvial deposits covering Tertiary gypsum. This data can be interpreted as indicating different mechanisms by which sinkholes form. Negative gravity anomalies reflect the movement of alluvial particles into deeper subsurface caves. Ground penetrating radar (GPR) anomalies may indicate formation of caves in the

G. BENITO

27

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

28

Generalized Diffuse Field Within a 2d Alluvial Basin: a Numerical Example  

NASA Astrophysics Data System (ADS)

Since the pioneering work of Aki (1957), the seismic noise has been used to infer the wave velocity distribution of soil formations. Later, diffuse-field concepts from room acoustics began to be used in elastodynamics by Weaver (1982) and flourished in many applications thanks to the contributions of Campillo and coworkers. It was established that diffusion like regimes are obtained when the field is produced by equipartitioned, uniform illumination. Within an elastodynamic diffuse-field the average correlation of the displacement field between two stations is proportional to the Green function of the system for those points. Usually, the surface waves can be interpreted by means of the retrieved Green function, from which very important information about the properties in depth can be obtained. Seismic noise and coda are frequently considered as diffuse-fields. This assumption is well supported by ideas of multiple scattering of waves and the resultant energy equipartition. There are few examples of numerically generated diffuse-fields. Some are based on random distributed forces (e.g. Sánchez-Sesma et al., 2006), while others used a set of plane waves with varying incidence angles and polarization (e.g. Sánchez-Sesma and Campillo 2006; Kawase et al. 2011). In this work we generate numerically a diffuse field within the Kawase and Aki (1989) 2D model using a random set of independent and uncorrelated incident plane P, SV and Rayleigh waves. For the simulations we use the indirect boundary element method (IBEM). Thus, we obtained the Green function for pairs of receivers by averaging correlations between different stations on the surface. In order to validate our results we compute the model's Green function as the response for a unit point load using the IBEM. Our numerical experiment provides guidelines for actual calculations of earthquakes in real alluvial basins.

Molina Villegas, J.; Baena, M.; Piña, J.; Perton, M.; Suarez, M.; Sanchez-Sesma, F. J.

2013-05-01

29

Late Quaternary alluvial fan response to climatic and tectonic base-level changes: Jakes Valley, Central Great Basin, USA  

NASA Astrophysics Data System (ADS)

Late Quaternary alluvial fans within the Jakes Valley region (White Pine County, Central Great Basin) are typically composed of up to 4 inset morphostratigraphic units. These units, Qf0 (oldest) through to Qf3 (youngest), are based upon field relationships (mapping & fan topographic profiles) and soil properties. Distal fan areas contain pluvial lake shoreline features (erosional benches and beach ridges) that record lake-level lowering since the last glacial maximum. Integration of the fan morphostratigraphy and pluvial lake shoreline features allows for the alluvial fan response to climate induced base-level lowering to be investigated. Geochronology is established by AMS C14 dating of gastropod shells sampled from a range of highstand (dates pending) through to lowstand (12,080 +/- 50 rcybp) beach ridges. Detailed analysis of two alluvial fans from the western (Cottonwood Fan) and eastern (Yamaha Fan) basin margins reveals some interesting differences in fan morphostratigraphy. The Cottonwood fan is characterised by a complete suite of morphostratigraphic units (Qf0-Qf3), whilst the Yamaha fan comprises only Qf0 and Qf3. The presence of a pronounced 17 m high scarp feature, some several hundreds of metres in length, within close proximity to the mountain front on the Cottonwood fan, suggests the occurrence of neotectonic activity. This extensional (?) faulting appears to be post QF0 and may have been responsible for influencing the observed stratigraphic differences between the Cottonwood and Yamaha fans via a tectonic lowering of base-level. Within this poster we explore the relative roles of climate and tectonic base-level lowering for alluvial fan development.

Stokes, M.; Garcia, A. F.

2003-12-01

30

RESERVOIR ARCHITECTURE IN A TERMINAL ALLUVIAL PLAIN: AN OUTCROP ANALOGUE STUDY (UPPER TRIASSIC, SOUTHERN GERMANY) PART II: CYCLICITY, CONTROLS AND MODELS  

Microsoft Academic Search

This outcrop analogue study investigates Triassic fluvial sandstones of the Stubensandstein Formation which were deposited on a terminal alluvial plain under semi- arid to sub-humid climatic conditions in the land-locked South German Keuper Basin. The Stubensandstein may serve as an analogue for reservoir units in comparable continental basins. Data came from studies of 13 large sandpits, together with a subsurface

J. Hornung; T. Aigner

2002-01-01

31

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

32

Seasonal Mineralogy and Biogeochemistry of an Arid-lands Hyporheic Corridor Along the Alluvial Rio Grande, New Mexico, USA  

Microsoft Academic Search

The Middle Rio Grande in central New Mexico flows through a semiarid, sand-dominated Quaternary rift basin. Flow regulation measures include dams, irrigation diversions, levees, and bank stabilization. These have caused severe eco-hydrologic impairment including 1) incision, lowered water tables, and the end of overbank flooding; 2) disruption of shallow groundwater cycling; 3) sediment depletion; 4) altered seasonal organic carbon dynamics;

D. S. Vinson; A. D. Pershall; M. N. Spilde; S. E. Block; L. J. Crossey; C. N. Dahm

2002-01-01

33

Water environmental degradation of the Heihe River Basin in arid northwestern China.  

PubMed

Water environmental degradation is a major issue in the Heihe River Basin belonging to the inland river basin of temperate arid zone in northwestern China. Mankind's activities, such as dense population and heavy dependence on irrigated agriculture, place immense pressure on available and limited water resources during the last century, especially the recent five decades. An investigation on the water environmental degradation in the Heihe River Basin and analysis of its causation were conducted. The results indicated that water environmental changes in the whole basin were tremendous mostly in the middle reaches, which reflected in surface water runoff change, decline of groundwater table and degeneration of surface water and groundwater quality. Some new forms of management based on traditional and scientific knowledge must be introduced to solve problems of water environmental degradation in the Heihe River Basin. PMID:16160787

Qi, Shan-Zhong; Luo, Fang

2005-09-01

34

Land-use change and its environmental impact in the Heihe River Basin, arid northwestern China  

NASA Astrophysics Data System (ADS)

Rapid land-use change has taken place in many arid and semi-arid regions of China over the last decade as the result of demand for food for its growing population. The Heihe River Basin, a typical inland river basin of temperate arid zone in northwestern China, was investigated to assess land-use change dynamics by the combined use of satellite remote sensing and geographical information systems (GIS), and to explore the interaction between these changes and the environment. Images were classified into six land-use types: cropland, forestland, grassland, water, urban or built-up land, and barren land. The objectives were to assess and analyze landscape change of land use/cover in Heihe River Basin over 15 years from 1987 to 2002. The results show that (1) grassland and barren land increase greatly by 22.3, and 268.2 km2, respectively, but water area decreased rapidly by 247.2 km2 in the upper reaches of Heihe River Basin; (2) cropland and urban or built-up land increased greatly by 174.9, and 64.6 km2, respectively, but grassland decreased rapidly by 210.3 km2 in the middle reaches of Heihe River Basin; and (3) barren land increased largely by 397.4 km2, but grassland degraded seriously and water area decreased obviously by 313.3, and 21.7 km2, respectively in the lower reaches of Heihe River Basin. These results show that significant changes in land-use occur within the whole basin over the study period and cause severe environmental degradation, such as water environmental changes (including surface water runoff change, decline of groundwater table and degeneration of surface water and groundwater quality), land desertification and salinization, and vegetation degeneracy.

Qi, Shanzhong; Luo, Fang

2006-07-01

35

Relations between climatic variability and hydrologic time series from four alluvial basins across the southwestern United States  

USGS Publications Warehouse

Hydrologic time series of groundwater levels, streamflow, precipitation, and tree-ring indices from four alluvial basins in the southwestern United States were spectrally analyzed, and then frequency components were reconstructed to isolate variability due to climatic variations on four time scales. Reconstructed components (RCs), from each time series, were compared to climatic indices like the Pacific Decadal Oscillation (PDO), North American Monsoon (NAM), and El Nin??o-Southern Oscillation (ENSO), to reveal that as much as 80% of RC variation can be correlated with climate variations on corresponding time scales. In most cases, the hydrologic RCs lag behind the climate indices by 1-36 months. In all four basins, PDO-like components were the largest contributors to cyclic hydrologic variability. Generally, California time series have more variation associated with PDO and ENSO than the Arizona series, and Arizona basins have more variation associated with NAM. ENSO cycles were present in all four basins but were the largest relative contributors in southeastern Arizona. Groundwater levels show a wide range of climate responses that can be correlated from well to well in the various basins, with climate responses found in unconfined and confined aquifers from pumping centers to mountain fronts. ?? Springer-Verlag 2006.

Hanson, R. T.; Dettinger, M. D.; Newhouse, M. W.

2006-01-01

36

Alluvial evidence for major climate and flow regime changes during the middle and late Quaternary in eastern central Australia  

Microsoft Academic Search

As a low-gradient arid region spanning the tropics to the temperate zone, the Lake Eyre basin has undergone gentle late Cenozoic crustal warping leading to substantial alluvial deposition, thereby forming repositories of evidence for palaeoclimatic and palaeohydrological changes from the Late Tertiary to the Holocene. Auger holes and bank exposures at five locations along the lower 500 km of Cooper Creek,

Gerald C. Nanson; David M. Price; Brian G. Jones; Jerry C. Maroulis; Maria Coleman; Hugo Bowman; Timothy J. Cohen; Timothy J. Pietsch; Joshua R. Larsen

2008-01-01

37

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

38

Study plan for the regional aquifer-system analysis of alluvial basins in south-central Arizona and adjacent states  

USGS Publications Warehouse

The U.S. Geological Survey has started a 4-year study of the alluvial basins in south-central Arizona and parts of California , Nevada, and New Mexico to describe the hydrologic setting, available groundwater resources, and effects of historical development on the groundwater system. To aid in the study, mathematical models of selected basins will be developed for appraising local and regional flow systems. Major components necessary to accomplish the study objectives include the accumulation of existing data on groundwater quantity and quality, entering the data into a computer file, identification of data deficiencies, and development of a program to remedy the deficiencies by collection of additional data. The approach to the study will be to develop and calibrate models of selected basins for which sufficient data exist and to develop interpretation-transfer techniques whereby general predevelopment and postdevelopment conceptual models of the hydrologic system in other basins may be synthesized. The end result of the project will be a better definition of the hydrologic parameters and a better understanding of the workings of the hydrologic system. The models can be used to study the effects of management alternatives and water-resources development on the system. (USGS)

Anderson, T. W.

1980-01-01

39

Sediment yield exceeds sediment production in arid region drainage basins  

Microsoft Academic Search

We use 10Be and 26Al to determine long-term sediment generation rates, identify significant sediment sources, and test for landscape steady state in Nahal Yael, an extensively studied, hyperarid drainage basin in southern Israel. Comparing a 33 yr sediment budget with 33 paired 10Be and 26Al analyses indicates that short-term sediment yield (113 138 t · km-2 · yr-1) exceeds long-term

Erik M. Clapp; Paul R. Bierman; Asher P. Schick; Judith Lekach; Yehouda Enzel; Marc Caffee

2000-01-01

40

Magnetostratigraphy of The Astronomically-forced Alluvial Fan To Lacustrine Sequences of The Teruel Basin (late Miocene, Spain)  

NASA Astrophysics Data System (ADS)

During the last years, more and more examples of allocyclic, astronomical forced variations in the continental record have been documented. Sedimentary hiatuses, tra- ditionally regarded as the primary reason for the absence of clear patterns of orbital signature in the terrestrial domain, may be absent or short, given the appropriate set- ting. Spanish endoreic basins, for instance, form a ideal setting for the registration of orbital-forced climate change, as has been demonstrated for the Middle Miocene distal-alluvial fan-floodplain to lacustrine deposits of the Calatayud Basin. Astronom- ical forcing of sedimentary cycles has also been demonstrated in the Late Miocene distal alluvial fan to lacustrine sequences of the Teruel Basin. The early Late Miocene Cascante and Cañizar sections South of the town of Teruel show distinct cyclic bed- ding of red and/or green mottled mudstones alternating with white carbonate beds, whereby the alternation is mainly controlled by precession and eccentricity. The car- bonate beds are interpreted as (shallow) lake highstands, which occur in response to submergence of the alluvial fan distal plain. Small mammal teeth have been recov- ered from organic-richer layers at the base of the carbonate cycles in the Cascante and Cañizar sections. The recovery of mammal remains in terrestrial Milankovitch forced settings is crucial for several reasons: 1) it provides a first approximate age estimation for the sequence, thereby constraining other sources of temporal information such as magnetostratigraphy; 2) it infers very accurate ages of the mammal localities after as- tronomical tuning of the cyclic patterns; 3) it formulates hypotheses on the climatic regime and its variability using precise correlations to the insolation curve and in- terpretation of phase relations; and 4) it confronts the astronomically-based climatic reconstruction with the paleoecological reconstructions and faunal changes observed in the mammals themselves. This will lead to a better understanding of the nature of the response terrestrial organisms exhibit to climatic change. Based on the cyclo- and magnetostratigraphy, two age models for the sections (10.1-9.4 Ma; 10.3-9.6 Ma) are possible. However, spectral analysis results and estimated duration of subchrons indicate a preference for the younger age model. Additional sampling for mammals and paleomagnetism is needed to solve the problem of the age models, to date more 1 precisely mammal subzones J1, 2 and 3, and to establish the exact relations between changes in the mammal communities and short- and long-term astronomical cycles. 2

van Dam, J.; Aziz, H. Abdul; Hilgen, F. J.; Krijgsman, W.

41

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

42

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

43

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

44

Integrated neural networks for monthly river flow estimation in arid inland basin of Northwest China  

NASA Astrophysics Data System (ADS)

Streamflow model including rainfall-runoff and river flow models play an important role in water resources management, especially in arid inland area. Traditional conceptual models have the disadvantage of requirement of spatial variation parameters about the physical characteristics of the catchments. To overcome this difficulty, in this study, several integrated Artificial Neural Networks (ANNs) were presented to estimate monthly river flow, and the models include the semi-distributed forms of ANNs that can explore spatial variation in hydrological process (such as rainfall distribution and evaporation distribution) and no requirement of physical characteristic parameters of the catchments. In an arid inland basin of Northwest, integrated ANNs were developed using hydrological and agricultural data, and its performance was compared with that of lumped ANN and local linear regression model (LLR). Results showed that the integrated ANNs perform well to estimate the monthly streamflow at outlet of mountain with Root Mean Square Error ( RMSE) of 0.36 × 10 7 m 3 and Relative Error ( RE) of 9%. Similarly, the integrated ANNs can also accurately estimate the monthly river flow downstream of the basin with RMSE of 0.35-0.38 × 10 7 m 3 and RE of 22-27%. When compared with integrated ANNs, the lumped ANN and LLR models have lower precision to simulate monthly streamflow in arid inland basin. Presented integrated ANN models retain the advantages of the semi-distributed models considering the heterogeneity and spatial variation of hydrological factors and the physical characteristics in the catchment, while taking advantage of the potential of ANNs as an effective tool in nonlinear mapping or functional relationship establishment. In contrast to traditional models either in the lumped ANN or in empirical regression forms, the new approach of integration of Artificial Neural Networks has shown great potential in streamflow modeling.

Huo, Zailin; Feng, Shaoyuan; Kang, Shaozhong; Huang, Guanhua; Wang, Fengxin; Guo, Ping

2012-02-01

45

Remotely-Sensed Regional-Scale Evapotranspiration of a Semi-Arid Great Basin Desert and its Relationship to Geomorphology, Soils, and Vegetation  

NASA Technical Reports Server (NTRS)

Landsat Thematic Mapper data is used to estimate instantaneous regional-scale surface water and energy fluxes in a semi-arid Great Basin desert of the western United States. Results suggest that it is possible to scale from point measurements of environmental state variables to regional estimates of water and energy exchange. This research characterizes the unifying thread in the classical climate-topography-soil-vegetation relation-the surface water and energy balance-through maps of the partitioning of energy throughout the landscape. The study was conducted in Goshute Valley of northeastern Nevada, which is characteristic of most faulted graben valleys of the Basin and Range Province of the western United States. The valley comprises a central playa and lake plain bordered by alluvial fans emanating from the surrounding mountains. The distribution of evapotranspiration (ET) is lowest in the middle reaches of the fans where the water table is deep and plants are small, resulting in low evaporation and transpiration. Highest ET occurs in the center of the valley, particularly in the playa, where limited to no vegetation occurs, but evaporation is relatively high because of a shallow water table and silty clay soil capable of large capillary movement. Intermediate values of ET are associated with large shrubs and is dominated by transpiration.

Laymon, C.; Quattrochi, D.; Malek, E.; Hipps, L.; Boettinger, J.; McCurdy, G.

1997-01-01

46

Remotely-Sensed Regional-Scale Evapotranspiration of a Semi-Arid Great Basin Desert and its Relationship to Geomorphology, Soils, and Vegetation  

NASA Technical Reports Server (NTRS)

Landsat thematic mapper data are used to estimate instantaneous regional-scale surface water and energy fluxes in a semi-arid Great Basin desert of the western United States. Results suggest that it is possible to scale from point measurements of environmental state variables to regional estimates of water and energy exchange. This research characterizes the unifying thread in the classical climate-topography-soil-vegetation relation -the surface water and energy balance-through maps of the partitioning of energy throughout the landscape. The study was conducted in Goshute Valley of northeastern Nevada, which is characteristic of most faulted graben valleys of the Basin and Range Province of the western United States. The valley comprises a central playa and lake plain bordered by alluvial fans emanating from the surrounding mountains. The distribution of evapotranspiration (ET) is lowest in the middle reaches of the fans where the water table is deep and plants are small, resulting in low evaporation and transpiration. Highest ET occurs in the center of the valley, particularly in the playa, where limited to no vegetation occurs, but evaporation is relatively high because of a shallow water table and silty clay soil capable of large capillary movement. Intermediate values of ET are associated with large shrubs and is dominated by transpiration.

Laymon, C.; Quattrochi, D.; Malek, E.; Hipps, L.; Boettinger, J.; McCurdy, G.

1998-01-01

47

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

48

Clay sized fraction and powdered whole-rock X-ray analyses from alluvial basin deposits in central and southern New Mexico  

USGS Publications Warehouse

As part of the study of the water quality and geochemistry of Southwest Alluvial Basins (SWAB) in parts of Colorado, New Mexico, and Texas, which is a Regional Aquifer-System Analysis (RASA) program, whole rock x-ray analysis and clay-size fraction mineralogy (x-ray) analysis of selected samples from alluvial basin deposits were done to investigate the types of minerals and clay types present in the aquifers. This was done to determine the plausible minerals and clay types in the aquifers that may be reacting with groundwater and affecting the water quality. The purpose of this report is only to present the whole rock x-ray and clay-fraction mineralogy data. Nineteen surface samples or samples from outcrop of Tertiary and Quaternary alluvial basin deposits in the central and southern Rio Grande rift were collected and analyzed. The analysis of the samples consisted of grain size analysis, and clay-size fraction mineralogy and semiquantitative analysis of the relative abundance of different clay mineral groups present. (USGS)

Anderholm, S. K.

1985-01-01

49

Physical stratigraphy and sedimentology of an alluvial fan delta complex (south Pyrenean basin, Spain)  

SciTech Connect

The Santa Liestra is comprised of four main stratigraphic units with a major stratigraphic unconformity separating unit 2 from unit 3. This unconformity is expressed by an abrupt facies change and large-scale shelf instability features, and it probably represents a depositional sequence boundary related to a phase of thrust movement within the Santa Liestra sequence. Field correlations on transverse cross sections through the basin show a typical foreland asymmetrical clastic wedge; these correlations also illustrate the sheet-like geometry of the fan delta-front deposits. This study of a large fan delta-front system furnishes insight into the complex interactions governing the geometry and sedimentological characteristics of potential petroleum reservoirs in foreland basin settings.

Crumeyrolle, P.

1988-08-01

50

Interaction of a river with an alluvial basin aquifer: Stable isotopes, salinity and water budgets  

NASA Astrophysics Data System (ADS)

SummaryDetailed sets of tracer data (isotopes, salinity) and the results of MODFLOW modeling of water budgets provide an unprecedented opportunity for comparing modeling with field data in the area where the Rio Grande enters the Hueco Bolson basin of Texas and Chihuahua. Water from the Rio Grande has recharged the Hueco Bolson aquifer to a depth of 300 m below the surface in the El Paso-Ciudad Juárez area, the depth of infiltration corresponding to the depth of ancestral Rio Grande fluvial sediments. Groundwater beneath the river exhibits complex isotope and salinity stratification. Post-dam (post -1916, type A) river water has infiltrated to depths up to 80 m. Pre-dam (type B) river water has infiltrated to 300 m depth near downtown El Paso, and has mixed with, or been displaced further downstream by high-salinity native Hueco Bolson groundwater (type C, present in the basin north of the river). Salinity and isotope boundaries do not correspond precisely. Isotope stratification corresponds to water residence time and (for type C) to degree of evaporation; the highest salinities are associated with the most evaporated water. Modeling of water budgets in the basin fill beneath the river predicts present-day mixing of water types B and C where changing rates of pumping have caused a reversal of groundwater flow direction between El Paso and Ciudad Juárez, and deep recharge of type B water under conditions prevailing in the 1960s.

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

2010-12-01

51

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

52

Estimation of alluvial-fill thickness in the Mimbres ground-water basin, New Mexico, from interpretation of isostatic residual gravity anomalies  

USGS Publications Warehouse

The geologic structure of the Mimbres ground-water basin in southwest New Mexico is characterized by north- and northwest-trending structural subbasins. Sedimentation of Miocene and Pliocene age has filled and obscured the boundaries of these subbasins and formed poten- tially productive aquifers of varied thickness. The location and depth of the subbasins can be esti- mated from analysis of isostatic residual gravity anomalies. Density contrasts of various basement lithologies generate complex regional gravity trends, which are convolved with the gravity signal from the Miocene and Pliocene alluvial fill. An iterative scheme was used to separate these regional gravity trends from the alluvial-fill grav- ity signal, which was inverted with estimated depth-density relations to compute the thickness of the alluvial fill at 1-kilometer spacing. The thickness estimates were constrained by explor- atory drill-hole information, interpreted seismic- refraction profiles, and location of bedrock lithol- ogy from surficial geologic mapping. The result- ing map of alluvial-fill thickness suggests large areas of thin alluvium that separate deep structural subbasins.

Heywood, Charles E.

2002-01-01

53

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

54

Ground water budget analysis and cross-formational leakage in an arid basin.  

PubMed

Ground water budget analysis in arid basins is substantially aided by integrated use of numerical models and environmental isotopes. Spatial variability of recharge, storage of water of both modern and pluvial age, and complex three-dimensional flow processes in these basins provide challenges to the development of a good conceptual model. Ground water age dating and mixing analysis with isotopic tracers complement standard hydrogeologic data that are collected and processed as an initial step in the development and calibration of a numerical model. Environmental isotopes can confirm or refute a priori assumptions of ground water flow, such as the general assumption that natural recharge occurs primarily along mountains and mountain fronts. Isotopes also serve as powerful tools during postaudits of numerical models. Ground water models provide a means of developing ground water budgets for entire model domains or for smaller regions within the model domain. These ground water budgets can be used to evaluate the impacts of pumping and estimate the magnitude of capture in the form of induced recharge from streams, as well as quantify storage changes within the system. The coupled analyses of ground water budget analysis and isotope sampling and analysis provide a means to confirm, refute, or modify conceptual models of ground water flow. PMID:18384598

Hutchison, William R; Hibbs, Barry J

2008-01-01

55

Stratigraphic architecture of alluvial-aeolian systems developed on active karst terrains: An Early Pleistocene example from the Ebro Basin (NE Spain)  

NASA Astrophysics Data System (ADS)

During the Early Pleistocene, fluvial, alluvial and aeolian depositional systems interacted in the central Ebro Basin, Spain, constructing wide alluvial plains over a Neogene evaporite substratum. Fluvial sediments, mainly longitudinal gravel bars and channels, are interdigitated with gravel mass flow and distal mudflat deposits. Aeolian sedimentation is registered as aeolian dunes and sand sheets. Episodes of fluvial deposition alternated with periods of alluvial fan progradation and aeolian deposition. These changes are related to climate-driven water availability. Stratigraphic units and deformation structures show synsedimentary karstification of the evaporite substratum that, although karst was not restricted to any particular climate scenario, was probably favoured during periods of high water availability. Karstification conditioned the development of local sedimentary depocentres which, in turn, influenced the distribution of sedimentary subenvironments as well as the accumulation and preservation of aeolian dunes and lacustrine-palustrine deposits. Stratigraphic architecture shows that thickening of the series due to karst subsidence did not occur homogeneously, but was controlled by diachronous subsidence resulting in numerous angular unconformities. In subsiding karst areas transport capacity was reduced and sediment preservation increased.

Gil, H.; Luzón, A.; Soriano, M. A.; Casado, I.; Pérez, A.; Yuste, A.; Pueyo, E.; Pocoví, A.

2013-10-01

56

Interaction of water components in the semi-arid Huasco and Limarí river basins, North Central Chile  

Microsoft Academic Search

For sustainable water resource management in semi-arid regions, sound information is required about interactions between the different components of the water system: rain\\/snow precipitation, surface\\/subsurface run-off, groundwater recharge. Exemplarily, the Huasco and Limarí river basins as water stressed river catchments have been studied by isotope and hydrochemical methods for (i) the origin of water, (ii) water quality, (iii) relations of

G. Strauch; R. Oyarzún; F. Reinstorf; J. Oyarzún; M. Schirmer; K. Knöller

2009-01-01

57

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

58

The impact of changing environments on the runoff regimes of the arid Heihe River basin, China  

NASA Astrophysics Data System (ADS)

This study analyzed the inter- and inner-annual variations of discharge regimes in the upper and mid reaches of the Heihe River basin. These variations then correlated with temperature and precipitation variations in the area. The differences between the runoff regimes at the upper and mid reaches were compared, and the human impacts on discharge variations in the Heihe River were discussed. The results indicate that in the upper reaches, the long-term trends and periods of discharge and precipitation correlate well. In the mid reaches, the discharge and temperature trends correlate well, and the short discharge and precipitation periods correlate well. Precipitation increases would generate more runoff in both the upper and mid reaches, but the effects of temperature increases on discharge are different in the upper and mid reaches. Temperature increases would enhance the glacial ablation processes and increase runoff in the upper reaches. However, temperature increases would increase the evaporation and decrease runoff in the mid reaches. After the 1980s, higher temperature enhanced snow and glacial melt, and increasing precipitation increased the discharge in the upper reaches. Although increasing precipitation increased some discharge, great human activities caused a notable discharge decrease in the 1990s in the mid reaches, especially during the spring to autumn when large amounts of water resources were used for irrigation. In summary, both precipitation and temperature impact the availability of water resources in the study area, and active and effective adaptation strategies should be developed to improve the efficiency of water resource exploration and to prevent the desertification processes in the arid Heihe River basin.

Sang, Yan-Fang; Wang, Zhonggen; Liu, Changming; Yu, Jingjie

2014-01-01

59

Regionalising a meso-catchment scale conceptual model for river basin management in the semi-arid environment  

NASA Astrophysics Data System (ADS)

Meso-scale catchments are often of great interest for water resources development and for development interventions aimed at uplifting rural livelihoods. However, in Sub-Saharan Africa IWRM planning in such catchments, and the basins they form part of, are often ungauged or constrained by poor data availability. Regionalisation of a hydrological model presents opportunities for prediction in ungauged basins and catchments. This study regionalises HBVx, derived from the conceptual hydrological model HBV, in the semi-arid Mzingwane Catchment, Limpopo Basin, Zimbabwe. Fifteen meso-catchments were studied, including three that were instrumented during the study. Discriminant analysis showed that the characteristics of catchments in the arid agro-ecological Region V were significantly different from those in semi-arid Region IV. Analysis of flow duration curves statistically separated sub-perennial catchments from (sub-)ephemeral catchments. Regionalised parameter sets for HBVx were derived from means of parameters from the sub-perennial catchments, the (sub-)ephemeral catchments and all catchments. The parameter sets that performed best in the regionalisation are characterised by slow infiltration with moderate/fast “overland flow”. These processes appear more extreme in more degraded catchments. This is points to benefits to be derived from conservation techniques that increase infiltration rate and from runoff farming. Faster, and possibly greater, sub-surface contribution to streamflow is expected from catchments underlain by granitic rocks. Calibration and regionalisation were more successful at the dekad (10 days) time step than when using daily or monthly data, and for the sub-perennial catchments than the (sub-)ephemeral catchments. However, none of the regionalised parameter sets yielded C NS ? 0.3 for half of the catchments. The HBVx model thus does offer some assistance to river basin planning in semi-arid basins, particularly for predicting flows in ungauged catchments at longer time steps, such as for water allocation purposes. However, the model is unreliable for more ephemeral and drier catchments. Without more reliable and longer rainfall and runoff data, regionalisation in semi-arid ephemeral catchments will remain highly challenging.

Love, David; Uhlenbrook, Stefan; van der Zaag, Pieter

60

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

61

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

62

Interaction of water components in the semi-arid Huasco and Limarí river basins, North Central Chile  

NASA Astrophysics Data System (ADS)

For sustainable water resource management in semi-arid regions, sound information is required about interactions between the different components of the water system: rain/snow precipitation, surface/subsurface run-off, groundwater recharge. Exemplarily, the Huasco and Limarí river basins as water stressed river catchments have been studied by isotope and hydrochemical methods for (i) the origin of water, (ii) water quality, (iii) relations of surface and groundwater. Applying the complex multi-isotopic and hydrochemical methodology to the water components of the Huasco and Limarí basins, a differentiation of water components concerning subsurface flow and river water along the catchment area and by anthropogenic impacts are detected. Sulphate and nitrate concentrations indicate remarkable input from mining and agricultural activities along the river catchment. The 2H-18O relations of river water and groundwater of both catchments point to the behaviour of river waters originated in an arid to semi-arid environment. Consequently, the groundwater from several production wells in the lower parts of the catchments is related to the rivers where the wells located, however, it can be distinguished from the river water. Using the hydrological water balance and the isotope mixing model, the interaction between surface and subsurface flows and river flow is estimated.

Strauch, G.; Oyarzún, R.; Reinstorf, F.; Oyarzún, J.; Schirmer, M.; Knöller, K.

2009-10-01

63

Geophysical and hydrogeologic investigations of two primary alluvial aquifers embedded in the southern San Andreas fault system: San Bernardino basin and upper Coachella Valley  

NASA Astrophysics Data System (ADS)

This study of alluvial aquifer basins in southern California is centered on observations of differential surface displacement and the search for the mechanisms of deformation. The San Bernardino basin and the Upper Coachella Valley aquifers are bound by range fronts and fault segments of the southern San Andreas fault system. I have worked to quantify long-term compaction in these groundwater dependent population centers with a unique synthesis of data and methodologies using Interferometric Synthetic Aperture Radar (InSAR) and groundwater data. My dissertation contributes to the understanding of alluvial aquifer heterogeneity and partitioning. I model hydrogeologic and tectonic interpretations of deformation where decades of overdraft conditions and ongoing aquifer development contribute to extreme rapid subsidence. I develop the Hydrogeologic InSAR Integration (HII) method for the characterization of surface deformation in aquifer basins. The method allows for the separation of superimposed hydraulic and/or tectonic processes in operation. This formalization of InSAR and groundwater level integration provides opportunities for application in other aquifer basins where overdraft conditions may be causing permanent loss of aquifer storage capacity through compaction. Sixteen years of SAR data for the Upper Coachella Valley exhibit rapid vertical surface displacement (? 48mm/a) in sharply bound areas of the western basin margin. Using well driller logs, I categorize a generalized facies analysis of the western basin margin, describing heterogeneity of the aquifer. This allowed for assessment of the relationships between observed surface deformation and sub-surface material properties. Providing the setting and context for the hydrogeologic evolution of California's primary aquifers, the mature San Andreas transform fault is studied extensively by a broad range of geoscientists. I present a compilation of observations of creep, line integrals across the Pacific-North America Plate Boundary, and strain tensor volumes for comparison to the Working Group 2007 (UCERF 2) seismicity-based deformation model. I find that the moment accumulation across the plate boundary is consistent with the deformation model, suggesting fault displacement observations within the plate boundary zone accurately capture the strain across the plate boundary. This dissertation includes co-authored materials previously published, and also includes unpublished work currently under revisions for submission to a technical journal.

Wisely, Beth Ann

64

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

65

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

66

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

67

Analysis of some peculiarities of the DREAM model parameterization in a semi-arid basin of Southern Italy  

NASA Astrophysics Data System (ADS)

Water resources management in semi-arid environments is a complex issue because of the time and spatial variability of weather and the insufficient monitoring network useful to derive input data for hydrological modelling. In this work a water balance model is revised with particular attention to the input dataset and the theoretical approach in order to improve the accuracy of the predicted outputs. The DREAM model (Manfreda et al., 2005) is applied in a semi-arid basin of Southern Italy (Carapelle torrent, basin area: 506 km2). Hydrological processes are computed on a grid schematization of the river which takes into account the spatial heterogeneity of the basin using distributed data concerning soil texture, land use, hydraulic characteristics and local slope. Time and spatial variability of vegetation coverage is considered using satellite data. Normalized Difference Vegetation Index values are converted into Leaf Area Index profiles to estimate interception and evapotranspiration. The performance of the hydrological model was improved varying four aspects of the model: the pedotransfers functions used to predict the soil hydraulic characteristics, the equations referring to the evapotranspiration process, the type of satellite images and the parameters used for calibration. Evapotranspiration is calculated using two different approaches: Thornthwaite and Penman-Monteith. Leaf Area Index is estimated using a linear regression LAI-NDVI (Caraux-Garson) and a logaritmic one (Beer). The calibration of the Beer law is carried out selecting some sample areas and comparing the literature LAI values to the simulated ones. The spatial resolution of the satellite data influences the hydrologic response: the use of the MODIS images instead of the NOAA-AVHRR ones determines higher values of evapotranspiration more realistic for Mediterranean environments. The analysis described will be useful to select the equations which are more suitable for semi-arid catchments and to individuate which factors need to be measured accurately in order to achieve better results in the model output.

Bisantino, T.; Gentile, F.; Iacobellis, V.; Milella, P.; Trisorio Liuzzi, G.

2009-04-01

68

Lower Eocene alluvial paleosols (Willwood Formation, Northwest Wyoming, U.S.A.) and their significance for paleoecology, paleoclimatology, and basin analysis  

USGS Publications Warehouse

The lower Eocene Willwood Formation of northwest Wyoming is a 700 m thick accumulation of alluvial floodplain and channel mudstones and sandstones, nearly all of which show paleopedogenic modifications. Pedogenesis of Willwood sandstones is indicated by taproot and vertebrate and invertebrate bioturbation, early local cementation by calcium carbonate, and thin illuviation cutans on clastic grains. Pedogenesis in Willwood mudstones is indicated by plant bioturbation, insect and other invertebrate burrow casts and lebensspuren; free iron, aluminum, and manganese mobilization, including hydromorphic gleying; sesquioxide and calcareous glaebule formation in lower parts of the solum; presence of clay-rich and organic carbon-rich zones; and well differentiated epipedons and albic and spodic horizons. Probable A horizons are also locally well developed. Occurrence of variegated paleosol units in thick floodplain mudstone deposits and their association with thin, lenticular, and unconnected fluvial sandstones in the Willwood Formation of the central and southeast Bighorn Basin suggest that these soils formed during times of rapid sediment accumulation. The tabular geometry and lateral persistence of soil units as well as the absence of catenization indicate that Willwood floodplains were broad and essentially featureless. All Willwood paleosols were developed on alluvial parent materials and are complex in that B horizons of younger paleosols were commonly superimposed upon and mask properties of suspected A and B horizons of the next older paleosols. The soils appear to be wet varieties of the Spodosol and Entisol groups (aquods and ferrods, and aquents, respectively), though thick, superposed and less mottled red, purple, and yellow paleosols resemble some ultisols. Most Willwood paleosols resemble warm temperate to subtropical alluvial soils that form today under alternating wet and dry conditions and (or) fluctuating water tables. The up-section decrease in frequency of gley mottles, increase in numerical proportion and thickness of red versus orange coloration, and increase in abundance of calcrete glaebules indicate better drained soils and probably drier climate in late Willwood time. This drying is believed to be related to creation of rain shadows and spacing of rainfall (but not necessarily decrease in absolute rainfall) due to progressive tectonic structural elevation of the mountainous margins of the Bighorn Basin. ?? 1981.

Bown, T. M.; Kraus, M. J.

1981-01-01

69

Mapping Ecological Processes and Ecosystem Services for Prioritizing Restoration Efforts in a Semi-arid Mediterranean River Basin  

NASA Astrophysics Data System (ADS)

Semi-arid Mediterranean regions are highly susceptible to desertification processes which can reduce the benefits that people obtain from healthy ecosystems and thus threaten human wellbeing. The European Union Biodiversity Strategy to 2020 recognizes the need to incorporate ecosystem services into land-use management, conservation, and restoration actions. The inclusion of ecosystem services into restoration actions and plans is an emerging area of research, and there are few documented approaches and guidelines on how to undertake such an exercise. This paper responds to this need, and we demonstrate an approach for identifying both key ecosystem services provisioning areas and the spatial relationship between ecological processes and services. A degraded semi-arid Mediterranean river basin in north east Spain was used as a case study area. We show that the quantification and mapping of services are the first step required for both optimizing and targeting of specific local areas for restoration. Additionally, we provide guidelines for restoration planning at a watershed scale; establishing priorities for improving the delivery of ecosystem services at this scale; and prioritizing the sub-watersheds for restoration based on their potential for delivering a combination of key ecosystem services for the entire basin.

Trabucchi, Mattia; O'Farrell, Patrick J.; Notivol, Eduardo; Comín, Francisco A.

2014-06-01

70

Mapping ecological processes and ecosystem services for prioritizing restoration efforts in a semi-arid Mediterranean river basin.  

PubMed

Semi-arid Mediterranean regions are highly susceptible to desertification processes which can reduce the benefits that people obtain from healthy ecosystems and thus threaten human wellbeing. The European Union Biodiversity Strategy to 2020 recognizes the need to incorporate ecosystem services into land-use management, conservation, and restoration actions. The inclusion of ecosystem services into restoration actions and plans is an emerging area of research, and there are few documented approaches and guidelines on how to undertake such an exercise. This paper responds to this need, and we demonstrate an approach for identifying both key ecosystem services provisioning areas and the spatial relationship between ecological processes and services. A degraded semi-arid Mediterranean river basin in north east Spain was used as a case study area. We show that the quantification and mapping of services are the first step required for both optimizing and targeting of specific local areas for restoration. Additionally, we provide guidelines for restoration planning at a watershed scale; establishing priorities for improving the delivery of ecosystem services at this scale; and prioritizing the sub-watersheds for restoration based on their potential for delivering a combination of key ecosystem services for the entire basin. PMID:24728487

Trabucchi, Mattia; O'Farrell, Patrick J; Notivol, Eduardo; Comín, Francisco A

2014-06-01

71

Watershed Airborne Telemetry Experimental Research (WATER): An Remote Sensing Experiment in a Typical Arid Region Inland River Basin of China  

NASA Astrophysics Data System (ADS)

Among the many land surface experiments have been carried out so far, arid and cold regions were paid little attentions. The land surface observations in arid and cold regions, both remotely sensed and in situ, need to be strengthened for a better understanding of hydrological and ecological processes at different scales. The Watershed Airborne Telemetry Experimental Research (WATER) is a simultaneous air-borne, satellite- borne, and ground-based remote sensing experiment conducted in the Heihe Basin, the second largest inland river basin in the northwest arid regions of China. The WATER is aiming at the research on water cycles, eco- hydrological and other land surface processes in catchment-scale. Data sets with high-resolution and spatiotemporal consistency will be generated based on this experiment. An integrated watershed model and a catchment-scale land/hydrological data assimilation system is proposed to be developed. The mission of WATER is to improve the observability, understanding, and predictability of hydrological and related ecological processes at catchmental scale, accumulate basic data for the development of watershed science and promote the applicability of quantitative remote sensing in watershed science studies. The objectives of the experiment will be (1) Observing major components of water cycle in three experiment areas, i.e., cold region, forest, and arid region hydrology experiment areas, by carrying out a simultaneous air-borne, satellite-borne, and ground-based experiment. (2) Developing the scaling method using airborne high-resolution remote sensing data and intensive in situ observations, and improving remote sensing retrieval models and algorithms of water cycle variables and corresponding ecological and other land variables/parameters. (3) Developing a catchment-scale land data assimilation system, which is capable of merging multi-source and multi-scale remote sensing data to generate high resolution and spatiotemporal consistent data sets in order to improve the predictability of water resources and environmental changes. (4) Using all the available data in the validation, possible improvement and development of catchment-scale hydrological and ecological models as well as decision support tools for water resource management.

Li, X.; Wang, J.; Ma, M.; Liu, Q.; Hu, Z.; Liu, Q.; Che, T.; Su, P.; Jin, R.; Wang, W.

2007-12-01

72

Volcaniclastic-alluvial sedimentation interaction in the Tordillo Fm., Upper Jurassic, Neuquén Basin (Argentina): An approach for paleogeographic and tectonic development.  

NASA Astrophysics Data System (ADS)

The Neuquén Basin is a Mesozoic back-arc basin located in central-western Argentina and eastern Chile and today incorporated into the Andean retro-arc foreland basin. The Upper Jurassic Tordillo Formation at the northern Neuquén Basin, Argentina, was developed during a generalized subsidence with still clear fault influence that followed a Late Triassic-Early Jurassic rifting phase. Although this formation comprises a multi-stage suit of predominantely alluvial sediments that is heterolithic in nature, aeolian and volcaniclastic sediments are also present. Volcaniclastic sediments are mainly andesitic in composition where subaerial pyroclastic flows and fallout deposits (and their remobilised sediments) are common. They are interbedded with fluvial braided and meandering sediments showing a clear interdependence. Sediment supply in the Neuquén Basin was markedly influenced by the uplift and later subsidence controlled by the magmatic activity. Explosive volcanic eruptions coupled with sporadic high rainfall events led to transportation and accumulation of large quantities of coarse volcaniclastic debris, including dm-scale blocks. Defined volcaniclastic facies include pyroclastic and epiclastic deposits of both primary and secondary origin. Pyroclastic deposits include flow and fall deposits, this latter with bombs and lapilli deposits. They are massive or show sequences. These latter normally show erosive base and are represented by 0.4 to 0.8m in thickness of reverse, normal and normal-reverse grading in which traction structures as lamination and cross-bedding appear. Associated flame, load and scour structures are also common at the top of the sequences. All of these deposits are related to a range that varies from subaerial to shallow water in origin. Some of those of shallow water may have resulted from the accumulation of decelerating turbulent suspensions of low density currents. Available detailed information from the evolution of the Neuquén Basin during the episodes without marine deposition is still scarce, particularly for the late Jurassic. This determines great limitations for reconstructing that evolution within a paleogeographic, magmatic and tectonic context. This study gives some clues for a better understanding of these aspects.

López-Gómez, José; Martín-Chivelet, Javier; Lago, Marceliano; Palma, Ricardo; Kietzmann, Diego

2010-05-01

73

Feedback mechanisms between water availability and water use in a semi-arid river basin: A spatially explicit multi-agent simulation approach  

Microsoft Academic Search

Understanding the processes responsible for the distribution of water availability over space and time is of great importance to spatial planning in a semi-arid river basin. In this study the usefulness of a multi- agent simulation (MAS) approach for representing these processes is discussed. A MAS model has been developed to represent local water use of farmers that both respond

Pieter R. Van Oel; Maarten S. Krol; Arjen Y. Hoekstra; Renzo R. Taddei

2010-01-01

74

Ground-water quality deterioration in arid areas: a case study of the Zerqa river basin as influenced by Khirbet Es-Samra waste water (Jordan)  

Microsoft Academic Search

The effects of the Khirbet Es-Samra Waste Water Treatment Plant (KS) on the deterioration of ground-water quality at Seil Zerqa basin were investigated in this study. The plant is located in an arid area in the eastern part of Jordan. It was built in 1985 to treat the waste water of about 60% of the Jordan population. It is composed

Atef Al-Kharabsheh

1999-01-01

75

History and Variability of aridity in the Tarim Basin since Late Miocene and its links to Tibetan Growth and global ice-volume change  

NASA Astrophysics Data System (ADS)

Modern climate environmental system in China is composed of monsoon region in the south-east where the annual precipitation is more than 400mm,, arid region in the north-west where the annual precipitation is less than 200mm, and the transitional zone between them. Results of numerical simulation show that the monsoon-arid environmental system of China has been influenced greatly by the growth of the Tibetan Plateau since Miocene (An et al., 2006). Numerous climate information, including the precipitation and temperature changes, has been obtained in the eastern monsoon-effected region, but that are very scarce in the western arid region. As the classical representative of the arid region, the Tarim Basin is very important to understand the coupling mechanisms among Tibet uplift, monsoon-arid environmental evolution, and global climate change. Lop Nor is located in the east part of the Tarim Basin, an ideal location to monitor drying of Asian inland. In year 2004, the LS2 core (39°46.65'N, 88°23.3'E, 1050.60m long) in the Lop Village was retrieved under the support of the project of Continental Environmental Scientific Drilling of China. Magnetostratigraphic result indicates that the age of the bottom of LS2 core is around 7.2Ma. Multiple proxies such as magnetic susceptibility, grain size, total organic carbon, total nitrogen, ?13Corg, and carbonate content as well as ?13C and ?18O of carbonate were generated to reconstruct the history and variability of aridity in the Tarim basin since 7.2Ma. The results reveal a remarkable drying in the Tarim basin around 5.5-5.3 Ma, possibly related to the growth of the Tibetan Plateau. Significant humid-dry variability under gradual drying trend is closely linked to global ice- volume change represented by marine ?18O records during the Plio-Pleistocene.

Chang, H.; Liu, W.; An, Z.; Sun, Y.; Song, C.; Wang, N.; Song, Y.; Fu, C.

2008-12-01

76

Comparing approaches for modeling spatially distributed direct recharge in a semi-arid region (Okanagan Basin, Canada)  

NASA Astrophysics Data System (ADS)

Spatially distributed recharge is compared at two different scales using three different modeling approaches within the semi-arid Okanagan Basin, British Columbia, Canada. Regional recharge was modeled by mapping results for one-dimensional soil columns from the water-balance code HELP (Hydrologic Evaluation of Landfill Performance, V3.80D). The regional model was then compared to two, independently derived, local-scale models to ensure local trends were captured in the regional model, and to compare modeling methods. Average annual recharge, predicted by the regional model, varied from no recharge to 186 mm/yr. For the north Okanagan (Vernon area), regional estimates were compared to Richards’ equation-based MIKE-SHE (V2007) estimates, which showed a significant difference in average annual recharge: 7 mm/yr (MIKE-SHE) and 109 mm/yr (HELP). In the south Okanagan (Oliver area), regional estimates were compared to high-resolution, local HELP estimates. Similar values of average annual recharge were obtained: 34 mm/yr (local) and 42 mm/yr (regional). A comparison with measured actual evapotranspiration data in the north Okanagan, showed HELP over-predicted recharge compared to MIKE-SHE by under-predicting evapotranspiration during summer months. Thus, the use of HELP in semi-arid areas may be limited if accurate estimates of recharge are needed. However, results may give satisfactory groundwater model calibrations results because of high uncertainty in hydraulic properties.

Liggett, Jessica E.; Allen, Diana M.

2010-03-01

77

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

78

Depositional environments in an alluvial-lacustrine system: molluscan paleoecology and lithofacies relations in upper part of Tongue River Member of Fort Union Formation, Powder River Basin, Wyoming  

SciTech Connect

The upper part of the Tongue River Member of the Fort Union Formation (Paleocene) in the northern Powder River basin, Wyoming, contains assemblages of excellently preserved nonmarine mollusks which occur in laterally continuous outcrops of diverse lithologic sequences and sedimentary structures. Three facies are recognized vertically within an alluvial-lacustrine system. The interfluvial lake and lake splay facies is characterized by sequences of coarsening-upward detritus, abundant continuous limestone beds, and few beds of discontinuous coal and continuous carbonaceous shale. Limestones contain two lacustrine mollusk assemblages: a locally reworked assemblage dominated by the bivalve Plesielliptio (two species), and the gastropods Viviparus, Lioplacodes (three species), and Clenchiella; and a quite-water assemblage dominated by sphaeriid bivalves. The interfluvial crevasse splay-crevasse channel facies is characterized by sequences of coarsening-upward detritus and few discontinuous limestone beds, separated vertically by thick, continuous coal and carbonaceous shale beds. This facies includes small crevasse channel sandstones which scour into splay sandstones. Biofabric of lacustrine mollusk assemblages, which are identical in composition (but with dwarfed species of Plesielliptio) to locally reworked lacustrine assemblages of the interfluvial lake and lake splay facies, reflects deterioration of lakes through active infilling by crevasses. The fluvial channel and interchannel facies is typified by thick channel sandstones laterally separated by sequences of coarsening-upward detritus, overbank sediments, and rare limestones. This facies includes thick, continuous coal and carbonaceous shale beds.

Hanley, J.H.; Flores, R.M.

1983-03-01

79

Identifying sources of groundwater nitrate contamination in a large alluvial groundwater basin with highly diversified intensive agricultural production.  

PubMed

Groundwater quality is a concern in alluvial aquifers underlying agricultural areas worldwide. Nitrate from land applied fertilizers or from animal waste can leach to groundwater and contaminate drinking water resources. The San Joaquin Valley, California, is an example of an agricultural landscape with a large diversity of field, vegetable, tree, nut, and citrus crops, but also confined animal feeding operations (CAFOs, here mostly dairies) that generate, store, and land apply large amounts of liquid manure. As in other such regions around the world, the rural population in the San Joaquin Valley relies almost exclusively on shallow domestic wells (?150 m deep), of which many have been affected by nitrate. Variability in crops, soil type, and depth to groundwater contribute to large variability in nitrate occurrence across the underlying aquifer system. The role of these factors in controlling groundwater nitrate contamination levels is examined. Two hundred domestic wells were sampled in two sub-regions of the San Joaquin Valley, Stanislaus and Merced (Stan/Mer) and Tulare and Kings (Tul/Kings) Counties. Forty six percent of well water samples in Tul/Kings and 42% of well water samples in Stan/Mer exceeded the MCL for nitrate (10mg/L NO3-N). For statistical analysis of nitrate contamination, 78 crop and landuse types were considered by grouping them into ten categories (CAFO, citrus, deciduous fruits and nuts, field crops, forage, native, pasture, truck crops, urban, and vineyards). Vadose zone thickness, soil type, well construction information, well proximity to dairies, and dominant landuse near the well were considered. In the Stan/Mer area, elevated nitrate levels in domestic wells most strongly correlate with the combination of very shallow (?21 m) water table and the presence of either CAFO derived animal waste applications or deciduous fruit and nut crops (synthetic fertilizer applications). In Tulare County, statistical data indicate that elevated nitrate levels in domestic well water are most strongly associated with citrus orchards when located in areas with a very shallow (?21 m) water table. Kings County had relatively few nitrate MCL exceedances in domestic wells, probably due to the deeper water table in Kings County. PMID:23800783

Lockhart, K M; King, A M; Harter, T

2013-08-01

80

Why conceptual groundwater flow models matter: a trans-boundary example from the arid Great Basin, western USA  

NASA Astrophysics Data System (ADS)

Spring and Snake valleys, western USA, are scheduled for development and groundwater export to Las Vegas, Nevada (USA). New work, compared to published studies, illustrates the critical role of conceptual models to underpin water withdrawals in arid regions. Interbasin flow studies suggest that 30-55 % of recharge to Snake Valley arrives from adjacent Spring Valley. This study, however, suggest little or no interbasin flow; rather, Spring and Snake valleys comprise separate systems. Contrary to expectation, ?D and ?18O contours are perpendicular to proposed interbasin flow paths. 14C age gradients up to 10 ka along interbasin flow paths indicate that old waters are not displaced by such fluxes. 14C and 3H patterns indicate local recharge occurs in adjacent mountain ranges and is transferred to basin-fill by losing streams, mountain front recharge, and upward leakage from carbonate bedrock beneath basins. The choice of conceptual models is critical for groundwater development. Simple analyses of water withdrawals indicate that monitoring discharges at desert springs is an inadequate protective measure. Once flows decline, recovery is lengthy even if pumping is stopped. The conceptual framework behind quantitative evaluations of sustainable yield is critical to determine the ability of a groundwater system to deliver sustained withdrawals.

Gillespie, J.; Nelson, S. T.; Mayo, A. L.; Tingey, D. G.

2012-09-01

81

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

82

Observed changes of drought\\/wetness episodes in the Pearl River basin, China, using the standardized precipitation index and aridity index  

Microsoft Academic Search

Monthly precipitation data of 42 rain stations over the Pearl River basin for 1960–2005 were analyzed to classify anomalously\\u000a wet and dry conditions by using the standardized precipitation index (SPI) and aridity index (I) for the rainy season (April–September) and winter (December–February). Trends of the number of wet and dry months decided\\u000a by SPI were detected with Mann-Kendall technique. Furthermore,

Qiang Zhang; Chong-Yu Xu; Zengxin Zhang

2009-01-01

83

Groundwater vulnerability to selenium in semi-arid environments: Amman Zarqa Basin, Jordan  

Microsoft Academic Search

An evaluation of ~250 samples of groundwater in the Amman Zarqa Basin for selenium along with other major and trace elements\\u000a showed that concentrations of Se ranged between 0.09 and 742 ?g\\/L, with an average value of about 24 ?g\\/L. Selenium concentrations\\u000a exceeded the recommended threshold for drinking water of the World Health Organization (WHO; 10 ?\\/L of Se) in 114 samples,\\u000a with

Mustafa Al Kuisi; Ahmad Abdel-Fattah

2010-01-01

84

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

85

Hydrogeology of an ancient arid closed basin: implications for tabular sandstone-hosted uranium deposits  

USGS Publications Warehouse

Hydrogeologic modeling shows that tabular-type uranium deposits in the Grants uranium region of the San Juan basin, New Mexico, formed in zones of ascending and discharging regional ground-water flow. The association of either lacustrine mudstone or actively subsiding structures and uranium deposits can best be explained by the occurrence of lakes at topographic depressions where ground water having different sources and compositions is likely to converge, mix, and discharge. Ascending and discharging flow also explains the association of uranium deposits with underlying evaporites and suggests a brine interface. The simulations contradict previous suggestions that ground water moved downward in the mudflat. -Author

Sanford, R. F.

1990-01-01

86

Modeling Spatial Recharge in the Arid Southern Okanagan Basin and Impacts of Future Predicted Climate Change  

NASA Astrophysics Data System (ADS)

Groundwater systems in arid regions will be particularly sensitive to climate change owing to the strong dependence of evapotranspiration rates on temperature, and potential shifts in the precipitation amounts and timing. In this study, future predicted climate change from three GCMs (CGCM1 GHG+A, CGCM3.1 A2, and HadCM3 A2) are used to evaluate the sensitivity of recharge in the Oliver region of the Okanagan Valley, south- central British Columbia, where annual precipitation is approximately 300~mm. Temperature data were downscaled using Statistical Downscaling Model (SDSM), while precipitation and solar radiation changes were estimated directly from the GCM data. Results for the region suggest that temperature will increase up to 4°C by the end of the century. Precipitation is expected to decrease in the spring, and increase in the fall. Solar radiation may decrease in the late summer. Shifts in climate, from present to future-predicted, were applied to the LARS-WG stochastic weather generator to generate daily stochastic weather series. Recharge was modeled spatially using output from the HELP hydrologic model applied to one-dimensional soil columns. An extensive valley-bottom soil database was used to determine both the spatial variation and vertical assemblage of soil horizons in the Oliver region. Soil hydraulic parameters were estimated from soil descriptions using pedotransfer functions through the ROSETTA program. Leaf area index (LAI) was estimated from ground-truthed Landsat 5 TM imagery, and surface slope was estimated from a digital elevation model. Irrigation application rates were modified for each climate scenario based on estimates of seasonal crop water demand. Daily irrigation was added to precipitation in irrigation districts using proportions of crop types along with daily climate and evapotranspiration data from LARS-WG. The two dominant crop classes are orchard (including peaches, cherries and apples) and vineyards (grapes). Recharge in irrigated areas is significantly higher, with irrigation return flow between 25--58%. Recharge results show a general increase of annual recharge, with the peak recharge shifting from March to February. Lower recharge rates and higher potential evapotranspiration rates are expected in the summer. The minor increase of annual recharge in future predicted climate states is due the shift of peak recharge from increased temperature. Growing season lengths, as determined from growing degree day accumulation, are expected to lengthen by 3--4 weeks by the 2080s.

Allen, D. M.; Toews, M. W.

2007-12-01

87

PLS regression-based pan evaporation and minimum-maximum temperature projections for an arid lake basin in India  

NASA Astrophysics Data System (ADS)

Climate change information required for impact studies is of a much finer scale than that provided by Global circulation models (GCMs). This paper presents an application of partial least squares (PLS) regression for downscaling GCMs output. Statistical downscaling models were developed using PLS regression for simultaneous downscaling of mean monthly maximum and minimum temperatures ( T max and T min) as well as pan evaporation to lake-basin scale in an arid region in India. The data used for evaluation were extracted from the NCEP/NCAR reanalysis dataset for the period 1948-2000 and the simulations from the third-generation Canadian Coupled Global Climate Model (CGCM3) for emission scenarios A1B, A2, B1, and COMMIT for the period 2001-2100. A simple multiplicative shift was used for correcting predictand values. The results demonstrated that the downscaling method was able to capture the relationship between the premises and the response. The analysis of downscaling models reveals that (1) the correlation coefficient for downscaled versus observed mean maximum temperature, mean minimum temperature, and pan evaporation was 0.94, 0.96, and 0.89, respectively; (2) an increasing trend is observed for T max and T min for A1B, A2, and B1 scenarios, whereas no trend is discerned with the COMMIT scenario; and (3) there was no trend observed in pan evaporation. In COMMIT scenario, atmospheric CO2 concentrations are held at year 2000 levels. Furthermore, a comparison with neural network technique shows the efficiency of PLS regression method.

Goyal, Manish Kumar; Ojha, C. S. P.

2011-10-01

88

Groundwater quality and management in arid and semi-arid regions: Case study, Central Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

This study presents a model budget for groundwater in the Central Eastern Desert of Egypt. The stable isotopic composition and hydrochemistry of groundwater samples collected from different aquifers were determined to identify recharge sources and water quality. Stable isotopic values suggest that shallow alluvial and fracture zone aquifers are recharged from seasonal precipitation, while groundwater in deeper sedimentary sub-basins is paleowater that was recharged during periods of less arid regional climate. Hydrochemical analysis indicates elevated salinity in each aquifer type, which is attributed to leaching and dissolution of terrestrial salts and to mixing with marine water. Groundwater from sedimentary sub-basin aquifers can be treated and used for drinking and domestic purposes. Groundwater from shallow alluvial and fracture zone wells is suitable for animal husbandry and mineral ore dressing. A model water budget shows that approximately 4.8 × 109 m3 of recoverable groundwater is stored in sedimentary sub-basin aquifers, or approximately 550 years of water at present utilization rates.

Amer, Reda; Ripperdan, Robert; Wang, Tao; Encarnación, John

2012-07-01

89

Valley-fill alluviation during the Little Ice Age (ca. A.D. 1400–1880), Paria River basin and southern Colorado Plateau, United States  

Microsoft Academic Search

Valley-fill alluvium deposited from ca. A.D. 1400 to 1880 is widespread in tribu- taries of the Paria River and is largely co- incident with the Little Ice Age epoch of global climate variability. Previous work showed that alluvium of this age is a map- pable stratigraphic unit in many of the larger alluvial valleys of the southern Col- orado Plateau.

Richard Hereford

2002-01-01

90

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

91

Remote sensing indices for monitoring land degradation in a semiarid to arid basin in Jordan  

NASA Astrophysics Data System (ADS)

Spectral reflectance for soils and vegetation of the Yarmouk basin were correlated with surficial soil properties and vegetation biomass and cover. The overall aim of the study was to identify bands suitable for assessing soil and vegetation as indices for land degradation and desertification. Results showed that vegetation was well separated from soils in the shortwave infrared wavelength at 1480 nm. For most sites, the differences in the bandwidths (in the range of 8.5 nm to 90 nm) did not improve the differentiation of vegetation types. For all wavelengths, stronger correlation values (maximum R2 = 0.85) were obtained for vegetation cover when compared with biomass (maximum R2 = 0.54). Soil spectral reflectance tended to increase with salinity, with maximum correlations obtained in the blue wavelengths (470±10 nm, 485±90 nm), followed by green and the NIR bands, where R2 values were around 0.60. Comparing results from radiometer measurements with results obtained from ASTER image bands showed that correlations tended to decrease with decreased spatial resolution for the investigated soil properties. For all wavelengths, spectral reflectance of degraded soils was higher than that for natural vegetation and irrigated crops with partial surface cover. Results of the study showed that the use of remote sensing indices related to vegetation cover and soil salinity would be recommended to map the extent of land degradation in the study area and similar environments. However, spectral unmixing should be applied to improve the correlations between satellite remote sensing data and surficial soil properties.

Al-Bakri, Jawad; Saoub, Hani; Nickling, William; Suleiman, Ayman; Salahat, Mohammad; Khresat, Saeb; Kandakji, Tareq

2012-10-01

92

Estimation of evapotranspiration in an arid region by remote sensing—A case study in the middle reaches of the Heihe River Basin  

NASA Astrophysics Data System (ADS)

Estimating surface evapotranspiration is extremely important for the study of water resources in arid regions. Data from the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer (NOAA/AVHRR), meteorological observations and data obtained from the Watershed Allied Telemetry Experimental Research (WATER) project in 2008 are applied to the evaporative fraction model to estimate evapotranspiration over the Heihe River Basin. The calculation method for the parameters used in the model and the evapotranspiration estimation results are analyzed and evaluated. The results observed within the oasis and the banks of the river suggest that more evapotranspiration occurs in the inland river basin in the arid region from May to September. Evapotranspiration values for the oasis, where the land surface types and vegetations are highly variable, are relatively small and heterogeneous. In the Gobi desert and other deserts with little vegetation, evapotranspiration remains at its lowest level during this period. These results reinforce the conclusion that rational utilization of water resources in the oasis is essential to manage the water resources in the inland river basin. In the remote sensing-based evapotranspiration model, the accuracy of the parameter estimate directly affects the accuracy of the evapotranspiration results; more accurate parameter values yield more precise values for evapotranspiration. However, when using the evaporative fraction to estimate regional evapotranspiration, better calculation results can be achieved only if evaporative fraction is constant in the daytime.

Li, Xingmin; Lu, Ling; Yang, Wenfeng; Cheng, Guodong

2012-07-01

93

Late Pleistocene alluvial plain sedimentation in Lower Narmada Valley, Western India: Palaeoenvironmental implications  

Microsoft Academic Search

Late Pleistocene fluvial sediments that were deposited in a slowly sinking basin are now exposed as 30–50 m high incised vertical cliffs all along the Lower Narmada Valley in western India. The exposed fluvial deposits have been classified into two sediment packages, alluvial fan sediments overlain by alluvial plain sediments. The alluvial plain sequence has not been studied previously. It

S. Bhandari; D. M. Maurya; L. S. Chamyal

2005-01-01

94

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

95

Environmental impacts on the hydrology of ephemeral streams and alluvial aquifers  

Microsoft Academic Search

In arid and semi-arid regions alluvial groundwater resources of ephemeral streams are highly important for water supplies and ecosystems. Recent projects have studied processes of indirect recharge in situ and in detail (Dahan et al., 2008; Klaus et al., 2008). Still, little is known about the vulnerability of these aquifers to environmental impacts like surface dam constructions, land-use changes and

C. Kuells; V. Marx; A. Bittner; R. Ellmies; M. Seely

2009-01-01

96

Large to intermediate-scale aquifer heterogeneity in fine-grain dominated alluvial fans (Cenozoic As Pontes Basin, northwestern Spain): insight based on three-dimensional geostatistical reconstruction  

NASA Astrophysics Data System (ADS)

Facies reconstructions are used in hydrogeology to improve the interpretation of aquifer permeability distribution. In the absence of sufficient data to define the heterogeneity due to geological processes, uncertainties in the distribution of aquifer hydrofacies and characteristics may appear. Geometric and geostatistical methods are used to understand and model aquifer hydrofacies distribution, providing models to improve comprehension and development of aquifers. However, these models require some input statistical parameters that can be difficult to infer from the study site. A three-dimensional reconstruction of a kilometer scale fine-grain dominated Cenozoic alluvial fan derived from more than 200 continuously cored, closely spaced, and regularly distributed wells is presented. The facies distributions were reconstructed using a genetic stratigraphic subdivision and a deterministic geostatistical algorithm. The reconstruction is only slightly affected by variations in the geostatistical input parameters because of the high-density data set. Analysis of the reconstruction allowed identification in the proximal to medial alluvial fan zones of several laterally extensive sand bodies with relatively higher permeability; these sand bodies were quantified in terms of volume, mean thickness, maximum area, and maximum equivalent diameter. These quantifications provide trends and geological scenarios for input statistical parameters to model aquifer systems in similar alluvial fan depositional settings.

Falivene, O.; Cabrera, L.; Sáez, A.

2007-08-01

97

[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

98

Rain events in an arid environment — Their distribution and ionic and isotopic composition patterns: Makhtesh Ramon Basin, Israel  

NASA Astrophysics Data System (ADS)

Forty-six individual rain events and successive fractions of these events were studied with a network of instruments in the arid Makhtesh Ramon Basin, southern Israel, during 1981/1983 Annual rainfall varied from 47 to 107 mm, number of rain events varied from 8 to 20 per year, start of the rainy season varied from September to January, termination of the rainy season varied from March to May and length of the rainy season varied from 4 to 9 months. About 85% of the rain events were recorded at more than one station, indicating an aerial distribution exceeding 20 km. A cliff amount effect was observed — the rain on the cliff (800 m) was 73% more than the rain at the bottom of the Makhtesh (500 m). Dust samples revealed the following soluble ions (in equivalents): Ca 2+ ? Mg 2+ > Na + ? K + and HCO -3 > Cl - > SO 2-4. The dust also contained CaCl 2. Rain composition of 61 analyzed samples revealed (in equivalents): Ca 2+ > Na + > Mg 2+ ? K + and HCO -3 > Cl - > SO 2-4, neutral pH of 7.1-7.6, and presence of CaCl 2. A similar pattern was observed in 54 samples collected during the same period at Sde Boker, 30 km north of the Ramon, thus typifying the Negev Heights. Two distinct sources of dissolved ions were inferred: dust, providing mainly Ca(HCO 3) 2, and cloud-borne sea spray, providing mainly Na +, Mg 2+, Cl - and SO 2-4. A chemical and isotopic effect was observed — the rain of the rainier year contained 34% less dissolved ions and was isotopically lighter in ? 18O by 54% than the rain of the less rainy year. A chemical and isotopic front effect was observed — the first fraction of the individual rain events contained more dissolved ions (32-69%) and was enriched by more ? 18O (31%) than the subsequent rain fractions. The observed rain distribution and chemical isotopic effects are discussed in terms of input sources, evaporation processes and altitude effects. The obtained data define rain and salt inputs into the hydrological systems.

Nativ, Ronit; Mazor, Emanuel

1987-01-01

99

Integrated Surface and Ground Water modeling of a tank cascaded sub basin using physically based model in a semi-arid region  

NASA Astrophysics Data System (ADS)

Hydrological Modeling of tank (small reservoirs) cascaded sub-basin of a semi-arid region is a complex process. Physically based approach can simulate the various processes in surface, unsaturated and saturated ground water zones of such sub basin in an integrated manner. The objectives of the study are (i) to characterize the study area to replicate the physical conditions of surface and saturated zones (ii) to carryout overland flow routing of a tank cascaded basin using physically based modular approach (iii) To simulate the ground water levels in the unconfined aquifer (iv) to study the surface and groundwater dynamics on incorporation of tank cascades in the integrated model. An integrated, physically based model MIKE 11 & MIKE SHE was applied to study the hydrological processes of a tank cascaded semi-arid basin in which flow through tanks were modeled using MIKE 11 and coupled with MIKE SHE in-order to best represent the surface water dynamics in a distributed manner. Sindapalli Uppodai sub-basin, Southern Tamilnadu, India is chosen as study area. There are 15 tanks connected in series forming a tank cascade. Other tanks and depressions in the sub basin are also considered for the study and their effectiveness were analysed. DEM was obtained from SRTM data. The maps such as drainage network, land use and soil are prepared. Soil sampling was carried out. The time series data of rainfall and climate parameters are given as input. The characterization of unconfined aquifer formation was done by Geo-Resistivity survey. 71 observation and pumping wells are monitored within and periphery of sub basin which are used for calibration of the model. The flow routing over the land is done by MIKE SHE's Overland Flow Module, using the diffusive wave approximation of the Saint Venant equation. The hydrograph of routed runoff from the tank cascaded catchment was obtained. The spatial and temporal variation of hydraulic head of the saturated ground water zone is simulated mathematically by three dimensional Darcy equation through ground water solver of MIKE SHE. Comprehensive budgeting of surface and ground water was made which will help the planners towards conserving and managing the scarce resources on a micro watershed level.

Ilampooranan, I.; Muthiah, K.; Athikesavan, R.

2013-05-01

100

Quantifying the effects of climate variability and human activities on runoff for Kaidu River Basin in arid region of northwest China  

NASA Astrophysics Data System (ADS)

Much attention has recently been focused on the effects that climate variability and human activities have had on runoff. In this study, data from the Kaidu River Basin in the arid region of northwest China were analyzed to investigate changes in annual runoff during the period of 1960-2009. The nonparametric Mann-Kendall test and the Mann-Kendall-Sneyers test were used to identify trend and step change point in the annual runoff. It was found that the basin had a significant increasing trend in annual runoff. Step change point in annual runoff was identified in the basin, which occurred in the year around 1993 dividing the long-term runoff series into a natural period (1960-1993) and a human-induced period (1994-2009). Then, the hydrologic sensitivity analysis method was employed to evaluate the effects of climate variability and human activities on mean annual runoff for the human-induced period based on precipitation and potential evapotranspiration. In 1994-2009, climate variability was the main factor that increased runoff with contribution of 90.5 %, while the increasing percentage due to human activities only accounted for 9.5 %, showing that runoff in the Kaidu River Basin is more sensitive to climate variability than human activities. This study quantitatively distinguishes the effects between climate variability and human activities on runoff, which can do duty for a reference for regional water resources assessment and management.

Chen, Zhongsheng; Chen, Yaning; Li, Baofu

2013-02-01

101

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

102

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

Microsoft Academic Search

Insufficient sub-surface hydraulic data from watersheds often hinders design of water resources structures. This is particularly true in developing countries and in watersheds with low population densities because well-drilling to obtain the hydraulic data is expensive. The objective of this study was to evaluate the applicability of ‘Brutsaert’ recession flow analysis to steeper and more arid watersheds than those that

Guillermo F. Mendoza; Tammo S. Steenhuis; M. Todd Walter; J.-Yves Parlange

2003-01-01

103

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

104

Variations in fluvial deposition on an alluvial plain: an example from the Tongue River Member of the Fort Union Formation (Paleocene), southeastern Powder River Basin, Wyoming, U.S.A.  

USGS Publications Warehouse

The Tongue River Member of the Paleocene Fort Union Formation is an important coal-bearing sedimentary unit in the Powder River Basin of Wyoming and Montana. We studied the depositional environments of a portion of this member at three sites 20 km apart in the southeastern part of the basin. Six lithofacies are recognized that we assign to five depositional facies categorized as either channel or interchannel-wetlands environments. (1) Type A sandstone is cross stratified and occurs as lenticular bodies with concave-upward basal surfaces; these bodies are assigned to the channel facies interpreted to be the product of low-sinuosity streams. (2) Type B sandstone occurs in parallel-bedded units containing mudrock partings and fossil plant debris; these units constitute the levee facies. (3) Type C sandstone typically lacks internal structure and occurs as tabular bodies separating finer grained deposits; these bodies represent the crevasse-splay facies. (4) Gray mudrock is generally nonlaminated and contains ironstone concretions; these deposits constitute the floodplain facies. (5) Carbonaceous shale and coal are assigned to the swamp facies. We recognize two styles of stream deposition in our study area. Laterally continuous complexes of single and multistoried channel bodies occur at our middle study site and we interpret these to be the deposits of sandy braided stream systems. In the two adjacent study sites, single and multistoried channel bodies are isolated in a matrix of finer-grained interchannel sediment suggesting deposition by anastomosed streams. A depositional model for our study area contains northwest-trending braided stream systems. Avulsions of these systems created anastomosed streams that flowed into adjacent interchannel areas. We propose that during late Paleocene a broad alluvial plain existed on the southeastern flank of the Powder River Basin. The braided streams that crossed this surface were tributaries to a northward-flowing, basin-axis trunk stream that existed to the west. ?? 1990.

Johnson, E. A.; Pierce, F. W.

1990-01-01

105

Enhanced sediment delivery in a changing climate in semi-arid mountain basins: Implications for water resource management and aquatic habitat in the northern Rocky Mountains  

NASA Astrophysics Data System (ADS)

The delivery and transport of sediment through mountain rivers affects aquatic habitat and water resource infrastructure. While climate change is widely expected to produce significant changes in hydrology and stream temperature, the effects of climate change on sediment yield have received less attention. In the northern Rocky Mountains, we expect climate change to increase sediment yield primarily through changes in temperature and hydrology that promote vegetation disturbances (i.e., wildfire, insect/pathogen outbreak, drought-related die off). Here, we synthesize existing data from central Idaho to explore (1) how sediment yields are likely to respond to climate change in semi-arid basins influenced by wildfire, (2) the potential consequences for aquatic habitat and water resource infrastructure, and (3) prospects for mitigating sediment yields in forest basins. Recent climate-driven increases in the severity and extent of wildfire suggest that basin-scale sediment yields within the next few years to decades could be greater than the long-term average rate of 146 T km - 2 year - 1 observed for central Idaho. These elevated sediment yields will likely impact downstream reservoirs, which were designed under conditions of historically lower sediment yield. Episodic erosional events (massive debris flows) that dominate post-fire sediment yields are impractical to mitigate, leaving road restoration as the most viable management opportunity for offsetting climate-related increases in sediment yield. However, short-term sediment yields from experimental basins with roads are three orders of magnitude smaller than those from individual fire-related events (on the order of 10 1 T km - 2 year - 1 compared to 10 4 T km - 2 year - 1 , respectively, for similar contributing areas), suggesting that road restoration would provide a relatively minor reduction in sediment loads at the basin-scale. Nevertheless, the ecologically damaging effects of fine sediment (material < 6 mm) chronically produced from roads will require continued management efforts.

Goode, Jaime R.; Luce, Charles H.; Buffington, John M.

2012-02-01

106

A multi-method approach to quantify groundwater/surface water-interactions in the semi-arid Hailiutu River basin, northwest China  

NASA Astrophysics Data System (ADS)

Identification and quantification of groundwater and surface-water interactions provide important scientific insights for managing groundwater and surface-water conjunctively. This is especially relevant in semi-arid areas where groundwater is often the main source to feed river discharge and to maintain groundwater dependent ecosystems. Multiple field measurements were taken in the semi-arid Bulang sub-catchment, part of the Hailiutu River basin in northwest China, to identify and quantify groundwater and surface-water interactions. Measurements of groundwater levels and stream stages for a 1-year investigation period indicate continuous groundwater discharge to the river. Temperature measurements of stream water, streambed deposits at different depths, and groundwater confirm the upward flow of groundwater to the stream during all seasons. Results of a tracer-based hydrograph separation exercise reveal that, even during heavy rainfall events, groundwater contributes much more to the increased stream discharge than direct surface runoff. Spatially distributed groundwater seepage along the stream was estimated using mass balance equations with electrical conductivity measurements during a constant salt injection experiment. Calculated groundwater seepage rates showed surprisingly large spatial variations for a relatively homogeneous sandy aquifer.

Yang, Zhi; Zhou, Yangxiao; Wenninger, Jochen; Uhlenbrook, Stefan

2014-05-01

107

Regional potentiometric-surface map of the Great Basin carbonate and alluvial aquifer system in Snake Valley and surrounding areas, Juab, Millard, and Beaver Counties, Utah, and White Pine and Lincoln Counties, Nevada  

USGS Publications Warehouse

Water-level measurements from 190 wells were used to develop a potentiometric-surface map of the east-central portion of the regional Great Basin carbonate and alluvial aquifer system in and around Snake Valley, eastern Nevada and western Utah. The map area covers approximately 9,000 square miles in Juab, Millard, and Beaver Counties, Utah, and White Pine and Lincoln Counties, Nevada. Recent (2007-2010) drilling by the Utah Geological Survey and U.S. Geological Survey has provided new data for areas where water-level measurements were previously unavailable. New water-level data were used to refine mapping of the pathways of intrabasin and interbasin groundwater flow. At 20 of these locations, nested observation wells provide vertical hydraulic gradient data and information related to the degree of connection between basin-fill aquifers and consolidated-rock aquifers. Multiple-year water-level hydrographs are also presented for 32 wells to illustrate the aquifer system's response to interannual climate variations and well withdrawals.

Gardner, Philip M.; Masbruch, Melissa D.; Plume, Russell W.; Buto, Susan G.

2011-01-01

108

Assessing impact of irrigation water on groundwater recharge and quality in arid environment using CFCs, tritium and stable isotopes, in the Zhangye Basin, Northwest China  

NASA Astrophysics Data System (ADS)

SummaryEnvironmental tracers CFCs, 18O, 2H and tritium were used to determine the natural groundwater recharge and the impact of irrigation activity on the groundwater system in the semi-arid Zhangye Basin of China. Groundwaters in the irrigated areas have been identified as mixtures containing fractions recharged in different periods of time. The CFC and 3H data show that the oldest fraction in the groundwater was recharged before 1950, whereas the younger fractions were recharged in different periods of time since 1950. Stable isotope ( 18O, 2H), CFC and electrical conductivity data show that most of the samples can be regarded as binary mixtures with the river/irrigation water presents the younger fraction and the regional groundwater presents the older fraction. Binary mixing model is used to estimate the age and fraction of the younger component. Most of the younger fraction was recharged after 1980s, in response to the increasing irrigation activities. Compared to local precipitation surface water plays a major role in recharging the aquifer in the irrigated area. The irrigation activity had more impact on the aquifer under thin unsaturated zone (<10 m), due to short travel times and high amounts of recharge, whereas it had less impact on the aquifer under thick unsaturated zone (tens of meters). CFCs are useful in identifying regions of different impact of irrigation return flow. The positive correlation between nitrate and CFC data show that contaminants are transported to the saturated zone by irrigation water. This study shows that in this semi-arid basin due to strong evaporation of infiltrating surface water and regional groundwater, ? 18O and EC values, in contrast to CFCs, do not show simple relationship with NO3- concentration in groundwater. Combined with a proper mixing model, however, they can provide evidences that the CFCs found in groundwater were introduced by infiltrating irrigation return flow and, therefore, reveal that human activities can produce a much localized water circulation and influence groundwater vulnerability.

Qin, Dajun; Qian, Yunping; Han, Liangfeng; Wang, Zhimin; Li, Chen; Zhao, Zhanfeng

2011-07-01

109

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

110

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

111

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

112

Study of crop coefficient and the ratio of soil evaporation to evapotranspiration in an irrigated maize field in an arid area of Yellow River Basin in China  

NASA Astrophysics Data System (ADS)

A field experiment was conducted in a maize field in 2006 in an arid area of the Yellow River Basin in China. The daytime evapotranspiration (ETc) and soil evaporation beneath the maize canopy ( E g) were measured by Bowen ratio energy balance method and micro-lysimeters, respectively. The results showed that the total ETc during maize growth season was 696 mm, and the maximum values occurred at about 90-140 days after sowing. The crop coefficient ( K c), which was calculated from the ratio of ETc to reference evapotranspiration (ET0), was quite different from the values reported by other researchers in similar climate areas, with average values of 0.34, 0.47, 1.0 and 0.9 for initial, development, mid-season and late-season stages, respectively. High correlations between leaf area index (LAI) and average K c for every 4 days were obtained. The total E g was 201.4 mm with average values ranged from 0.92 to 2.05 for four growth stages of maize; and accounted for around 28.9 % of ETc. The ratio E g/ETc showed high negative relationship with LAI. These results were very important in precise management of irrigation for maize in Yellow River Basin areas.

Zhang, Chuan; Yan, Haofang; Shi, Haibin; Sugimoto, Hideki

2013-08-01

113

The problems of overexploitation of aquifers in semi-arid areas: the Murcia Region and the Segura Basin (South-east Spain) case  

NASA Astrophysics Data System (ADS)

A general analysis of the problems arising from aquifer exploitation in semi-arid areas such as the Autonomous Region of Murcia, which belongs to the Segura Basin is presented, with particular reference to the Ascoy-Sopalmo aquifer, which is the most overexploited aquifer in Spain. It has suffered intense overabstraction over the last forty years, given renewable water resources of 2 Mm3 yr-1 and abstractions amounting to as much as 55 Mm3 yr-1. This has resulted in the drying of springs, continuous drawdown of water levels (5 m yr-1); piezometric drops (over 30 m in one year, as a consequence of it being a karstic aquifer); increase in pumping costs (elevating water from more than 320 m depth); abandoning of wells (45 reduced to 20), diminishing groundwater reserves, and deteriorating water quality (progressing from a mixed sodium bicarbonate-chloride facies to a sodium chloride one). This is a prime example of poor management with disastrous consequences. In this sense, a series of internal measures is proposed to alleviate the overexploitation of this aquifer and of the Segura Basin, with the aim of contributing to a sustainable future.

Rodríguez-Estrella, T.

2012-05-01

114

An integrative approach to sustainable groundwater and associated groundwater-dependent system management in arid karst aquifers: Cuatrociénegas Basin, Mexico  

Microsoft Academic Search

The Cuatrociénegas Basin (CCB), Coahuila, Mexico, is a UNESCO Biosphere Reserve with approximately 500 desert springs and associated groundwater-dependent ecosystems (called ciénegas). The reserve protects over 70 endemic species of fish, turtles, mollusks, snails, and other endangered biodiversity, as well as a diversity of globally extremely rare, active freshwater stromatolites. Groundwater development for agriculture in adjacent upgradient valleys threatens spring

Nuevo León

115

Redbeds from the Middle Muschelkalk (Middle Triassic) of the SW Germanic Basin: arid environments from Pangea's interior  

Microsoft Academic Search

The facies of a redbed succession from the lower Middle Muschelkalk of the SW Germanic Basin allows reconstruction of the depositional environment and inference with regard to the climate in a little studied part of Pangea's interior. The redbeds are dominated by fine-grained terrigenous deposits, with both intercalated thin sandstone and carbonate beds. The clastics were derived from the nearby

A. Vecsei; T. Mandau

2002-01-01

116

Mississippi Alluvial Valley  

USGS Publications Warehouse

Available data are summarized according to the following major topics: (1) characteristics of the Mississippi Alluvial Valley (MAV); (2) waterfowl populations associated with the MAV; (3) habitat requirements of migrating and wintering waterfowl in the MAV; (4) current habitat management practices in the MAV, including croplands, moist-soil impoundments, and forested wetlands; (5) status and classification of winter habitat in the MAV; and (6) research and management information needs.

Reinecke, K.J.; Kaminski, R.M.; Moorhead, D.J.; Hodges, J.D.; Nasser, J. R.

1989-01-01

117

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

118

[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

119

[Stem sap flow of grape under different drip irrigation patterns and its relationships with environmental factors in arid oasis region of Shiyang River basin].  

PubMed

This paper studied the stem sap flow of grape in arid oasis region of Shiyang River basin under conventional drip irrigation (CDI), alternate drip irrigation (ADI), and fixed drip irrigation (FDI), and its relationships with meteorological conditions and soil moisture content. The results showed that the stem sap flow of grape had an obvious day-night rhythm synchronous with solar radiation, and was significantly higher under CDI than under ADI and FDI during new branch growth and flowering stages. Solar radiation and air temperature were the main meteorological factors affecting the hourly sap flow, and the daily stem sap flow had linear relationships with daily air temperature and wind speed. The correlation coefficients between the stem sap flow and the meteorological factors ranked in the order of CDI > ADI > FDI. There was a significant correlation between daily stem sap flow and reference crop evapotranspiration (ET0). Compared with CDI, ADI could save 50% of irrigation water while the stem sap flow only reduced by 6.56%, and an obvious compensation effect between stem sap flow and hydraulic conductivity was observed. PMID:18464634

Du, Tai-Sheng; Kang, Shao-Zhong; Zhang, Bao-Zhong; Li, Si-En; Yang, Xiu-Ying

2008-02-01

120

Glacier contribution to flow in two high-altitude streams of the semi-arid Huasco Basin, northern-central Chile  

NASA Astrophysics Data System (ADS)

In the semi-arid north-central Chile, populated lowlands rely on runoff and groundwater recharge generated in the high altitude areas of the Andes mountain range. In spite of its importance in terms of water resources, the water balance in these areas is poorly known. In particular, the relative contribution of the cryosphere components (snowpack, glaciers, rock glaciers) to the regional water balance has not been thoroughly evaluated yet. We examine the hydrological importance of glaciers in the case of two well-monitored high-altitude watersheds of the Huasco Basin in northern-central Chile (29°S). We use data from a five years glaciological monitoring program to assess the quantity of water that comes from glaciers fusion per watershed. Then, we compare it with the measured discharge at five stream gauge stations located between 2620 m and 3980 m. The results reveal a substantial contribution of the glaciers to the hydrological balance of the study area. At the regional scale, the water balance is dominated by the snowpack dynamics.

Gascoin, Simon; Ponce, Rodrigo; Kinnard, Christophe; MacDonell, Shelley

2010-05-01

121

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

122

Environmental flow requirements in arid zone rivers--a case study from the Lake Eyre Basin, central Australia.  

PubMed

The ARIDFLO project takes a multi-disciplinary approach to the collection and analysis of data required to formulate appropriate environmental flow requirements for rivers in the Lake Eyre Basin. The key drivers of the ecological processes underpinning the health of these rivers are identified by modelling whole-of-ecosystem biological responses to hydrological events over a range of spatial and temporal scales. First, the hydrology of these poorly gauged (often ungauged) rivers needs to be modelled and validated to mimic real flow and inundation patterns at the catchment, reach and waterbody scale. Modelled and actual discharge data are then used to provide a suite of hydrological predictor variables which, in conjunction with other environmental variables, are used to model observed biotic responses. The key hydrologic and environmental drivers identified by the statistical models need to be taken into account when determining environmental flow requirements for these river systems. Further work is required to assess the predictive power of the models in the highly variable, complex systems of the Lake Eyre Basin rivers. PMID:14653635

Costelloe, J F; Puckridge, J T; Reid, J R W; Pritchard, J; Hudson, P; Bailey, V; Good, M

2003-01-01

123

Gully incision as a key factor in desertification in an arid environment, the Negev highlands, Israel  

Microsoft Academic Search

Gully incision has been eroding the alluvial sediments and loess soils deposited and developed along the valleys in the arid and semiarid regions of Israel. This phenomenon is critical in the arid regions of the Negev Highlands where the agricultural fields, the main floral biomass and the areas which have the highest grazing value, are limited to narrow valleys filled

Y. Avni

2005-01-01

124

Sedimentary facies, depositional environments and palaeogeographic evolution of the Neogene Denizli Basin, SW Anatolia, Turkey  

NASA Astrophysics Data System (ADS)

The Denizli Basin (southwestern Anatolia, Turkey) contains a record of environmental changes dating since the Early Miocene. Detailed facies analysis of the Neogene formations in this half-graben enables us to document successive depositional regimes and palaeogeographic settings. Sedimentation commenced in the Early Miocene with the deposition of alluvial-fan and fluvial facies (K?z?lburun Formation). At this stage, alluvial fans sourced from elevated areas to the south prograded towards the basin centre. The Middle Miocene time saw the establishment of marginal lacustrine and wetland environments followed by the development of a shallow lake (Sazak Formation). The uppermost part of this unit consists of evaporitic saline lake and saline mudflat facies that grade upward into brackish lacustrine deposits of Late Miocene-Pliocene age (Kolankaya Formation). The lake became shallower at the end of the Pliocene time, as is indicated by expansion shoreface/foreshore facies. In the Early Quaternary, the Denizli Basin was transformed into a graben by the activation of ESE-trending normal faults. Alluvial fans were active at the basin margins, whereas a meandering river system occupied the basin central part. Oxygen isotope data from carbonates in the successive formations show an alternation of wetter climatic periods, when fresh water settings predominated, and very arid periods, when the basin hosted brackish to hypersaline lakes. The Neogene sedimentation was controlled by an active, ESE-trending major normal fault along the basin's southern margin and by climatically induced lake-level changes. The deposition was more or less continuous from the Early Miocene to Late Pliocene time, with local unconformities developed only in the uppermost part of the basin-fill succession. The unconformable base of the overlying Quaternary deposits reflects the basin's transformation from a half-graben into a graben system.

Alçiçek, Hülya; Varol, Baki; Özkul, Mehmet

2007-12-01

125

Evaluation of the importance of clay confining units on groundwater flow in alluvial basins using solute and isotope tracers: the case of Middle San Pedro Basin in southeastern Arizona (USA)  

NASA Astrophysics Data System (ADS)

As groundwater becomes an increasingly important water resource worldwide, it is essential to understand how local geology affects groundwater quality, flowpaths and residence times. This study utilized multiple tracers to improve conceptual and numerical models of groundwater flow in the Middle San Pedro Basin in southeastern Arizona (USA) by determining recharge areas, compartmentalization of water sources, flowpaths and residence times. Ninety-five groundwater and surface-water samples were analyzed for major ion chemistry (water type and Ca/Sr ratios) and stable (18O, 2H, 13C) and radiogenic (3H, 14C) isotopes, and resulting data were used in conjunction with hydrogeologic information (e.g. hydraulic head and hydrostratigraphy). Results show that recent recharge (<60 years) has occurred within mountain systems along the basin margins and in shallow floodplain aquifers adjacent to the San Pedro River. Groundwater in the lower basin fill aquifer (semi confined) was recharged at high elevation in the fractured bedrock and has been extensively modified by water-rock reactions (increasing F and Sr, decreasing 14C) over long timescales (up to 35,000 years BP). Distinct solute and isotope geochemistries between the lower and upper basin fill aquifers show the importance of a clay confining unit on groundwater flow in the basin, which minimizes vertical groundwater movement.

Hopkins, Candice B.; McIntosh, Jennifer C.; Eastoe, Chris; Dickinson, Jesse E.; Meixner, Thomas

2014-06-01

126

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

127

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

128

Point sources of emerging contaminants along the Colorado River Basin: source water for the arid Southwestern United States.  

PubMed

Emerging contaminants (ECs) (e.g., pharmaceuticals, illicit drugs, personal care products) have been detected in waters across the United States. The objective of this study was to evaluate point sources of ECs along the Colorado River, from the headwaters in Colorado to the Gulf of California. At selected locations in the Colorado River Basin (sites in Colorado, Utah, Nevada, Arizona, and California), waste stream tributaries and receiving surface waters were sampled using either grab sampling or polar organic chemical integrative samplers (POCIS). The grab samples were extracted using solid-phase cartridge extraction (SPE), and the POCIS sorbents were transferred into empty SPEs and eluted with methanol. All extracts were prepared for, and analyzed by, liquid chromatography-electrospray-ion trap mass spectrometry (LC-ESI-ITMS). Log D(OW) values were calculated for all ECs in the study and compared to the empirical data collected. POCIS extracts were screened for the presence of estrogenic chemicals using the yeast estrogen screen (YES) assay. Extracts from the 2008 POCIS deployment in the Las Vegas Wash showed the second highest estrogenicity response. In the grab samples, azithromycin (an antibiotic) was detected in all but one urban waste stream, with concentrations ranging from 30ng/L to 2800ng/L. Concentration levels of azithromycin, methamphetamine and pseudoephedrine showed temporal variation from the Tucson WWTP. Those ECs that were detected in the main surface water channels (those that are diverted for urban use and irrigation along the Colorado River) were in the region of the limit-of-detection (e.g., 10ng/L), but most were below detection limits. PMID:22684090

Jones-Lepp, Tammy L; Sanchez, Charles; Alvarez, David A; Wilson, Doyle C; Taniguchi-Fu, Randi-Laurant

2012-07-15

129

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

130

Glacier contribution to flow in two high-altitude streams of the semi-arid Huasco Basin, northern-central Chile  

Microsoft Academic Search

In the semi-arid north-central Chile, populated lowlands rely on runoff and groundwater recharge generated in the high altitude areas of the Andes mountain range. In spite of its importance in terms of water resources, the water balance in these areas is poorly known. In particular, the relative contribution of the cryosphere components (snowpack, glaciers, rock glaciers) to the regional water

Simon Gascoin; Rodrigo Ponce; Christophe Kinnard; Shelley MacDonell

2010-01-01

131

Case studies of groundwater - surface water interactions and scale relationships in small alluvial aquifers  

Microsoft Academic Search

An alluvial aquifer can be described as a groundwater system, generally unconfined, that is\\u000ahosted in laterally discontinuous layers of gravel, sand, silt and clay, deposited by a river in a\\u000ariver channel, banks or flood plain. In semi-arid regions, streams that are associated with\\u000aalluvial aquifers tend to vary from discharge water bodies in the dry season, to recharge

David Love; Hamer de Wouter; Richard J. S. Owen; Martijn Booij; Stefan Uhlenbrook; Arjen Y. Hoekstra; Zaag van der Pieter

2007-01-01

132

Surface roughness as a calibrated proxy for dating alluvial surfaces  

NASA Astrophysics Data System (ADS)

Determining the age of alluvial deposits, which often constitute effective recorders of tectonic and climatic signals, is a pivotal component in many quantitative studies of recent tectonic activity, past climatic variations and landscape evolution processes. In arid to semi-arid desert environments the scarcity in suitable materials for dating commonly implies that numerical dating of alluvial surfaces remains a challenging and fairly expensive task, carried out on an opportunistic basis and typically requiring substantial commitment of resources. With the goal of addressing this problem, we present a new and widely applicable surface dating technique that builds on surface roughness as a quantitative calibrated proxy for the age of alluvial surfaces in desert environments. The well-studied development of reg soils provides the physical basis for the approach, and recent technological advances in the form of portable ground-based laser scanners (LiDAR), facilitate its application by allowing quantitative high resolution (~several millimeters) 3D characterization of the roughness of alluvial chronosequences as they mature into smooth and stable desert pavements. We construct regional age-roughness calibration curves using 'conventional' numerical dating techniques and LiDAR to quantitatively characterize the evolution trends and time-scales associated with roughness changes of reg soils through time. Here, we present results from two previously dated late Quaternary alluvial chronosequences along the Dead Sea Transform in the hyper-arid Negev desert of southern Israel. LiDAR scanning was applied on representative areas (~30-50 m2) of 10 separate terraces ranging from rough (active surfaces) to fairly smooth surfaces with well-developed pavements displaying an OSL age of 87 kyr. Power spectral density (PSD) analysis was used to characterize the roughness evolution trend of these terraces: We find typical and recurring time-dependent changes in the offset as well as shape of the PSD curves in both chronosequences: PSD offset is continuously reduced over time reflecting the overall reduction in the amplitude of roughness at all wavelengths. All PSD curves display moderation of slopes at the longer wavelengths, which consistently increases with increasing surface age. The kink point itself in the PSD curves is systematically shifted to shorter wavelengths. This characteristic evolution of PSD offset and slope moderation at longer wavelengths reflects the typical break up of boulder-sized clasts through time as such reg soil surfaces mature into well-developed desert pavements. Deviation of the PSD curve from the characteristic evolution pattern also serves as an indication in cases where the natural surface evolution was interrupted. Accordingly, we thus suggest that with suitable regional calibration curves, PSD analysis of desert alluvial surfaces can serve as a practical and quantitative proxy for constraining surface age in places where 'conventional' dating cannot be applied.

Mushkin, A.; Sagy, A.; Trabelci, E.

2012-12-01

133

Taphonomy and paleoecology of nonmarine mollusca: indicators of alluvial plain lacustrine sedimentation, upper part of the Tongue River Member, Fort Union Formation ( Paleocene), Northern Powder River Basin, Wyoming and Montana ( USA).  

USGS Publications Warehouse

The composition, species abundances, and spatial and temporal distributions of mollusc assemblages were controlled by the environments in which they lived and the depositional processes that affected the molluscs after death and before final burial. Post-mortem transport, reworking and concentration of shells, and mixing of faunal elements from discrete habitats produced a taphonomic 'overprint' on assemblage characteristics that directly reflects the processes of alluvial plain and floodbasin lacustrine sedimentation. The 'overprint' can be interpreted from outcrop analysis of molluscan biofabric, which consists of: 1) orientation, fragmentation, size-sorting, abrasion, density, and dispersion of shells, 2) the nature and extent of shell-infilling, and 3) ratio of articulated to disarticulated bivalves. Taphonomic characteristics were used with sedimentological properties to differentiate in-place, reworked, transported, and ecologically mixed mollusc assemblages. This study also defines the paleoecology of habitat preferences of mollusc species as a basis for recognition of the environments in which these assemblages were deposited: 1) large floodbasin lakes, 2) small floodbasin lakes, and 3) crevasse deltas and splays. Integration of sedimentology and paleoecology provides an interdisciplinary approach to the interpretation of alluvial environments through time in the Tongue River Member. -Authors

Hanley, J. H.; Flores, R. M.

1987-01-01

134

Ephemeral flow modelling in arid regions  

Microsoft Academic Search

Flow hydrographs in arid upland basins, where the runoff is directly related to the rainfall, are simulated by a combination of regression and differential equation techniques. The rising limb of the hydrograph is modelled through a regression analysis and the recession portion through a conceptual analog of discharge from a single leaky reservoir, which is described by a continuity equation

K. D. Sharma; J. S. R. Murthy

1996-01-01

135

Climatic controls on late Pleistocene alluvial fans, Cyprus  

NASA Astrophysics Data System (ADS)

Alluvial fans are commonly associated with tectonically active mountain ranges and tectonism is frequently held responsible for abrupt coarsening and cyclical sedimentation of alluvial fan sequences. Whilst it is accepted that tectonism provides the opportunity for alluvial fan development through the creation of topography, increasing gradients of fluvial systems supplying sediments, and creating accommodation for the storage of sediment flux, the role of climate in fan development is frequently neglected. The hypothesis that climatically controlled events can produce recognisable sedimentary signatures in alluvial fan deposits is tested in the active supra-subduction zone setting of the late Pleistocene of southern Cyprus. This study demonstrates through architectural analysis and the reconstruction of palaeoflood hydrology a recorded pattern of increasing and decreasing palaeoflow dynamics, with switches from a wetter to drier mode, clearly exhibited by changes in the sedimentology of the fan. At the present day Cyprus has a semi-arid climate and is influenced by a strongly seasonal rainfall pattern, largely restricted to the winter months (plus rare occurrences of summer cyclones). However at precession minima increased activity of western Mediterranean depressions produces wetter summers. Using inference we propose that longer-term increases in rainfall increased river discharge as recorded in the fan palaeoflood hydrology and occurred at minima in the precession. These periods correlate with the deposition of conglomeratic channels and open framework gravels. Drier periods are exhibited by sandier braided fluvial deposits. Shorter term or seasonal change is recorded in the form of 2nd and 3rd low order bounding surfaces. This increased activity of Mediterranean summer depressions increased precipitation to the wider Levantine area and was coincident with increased intensity of the north African and Indian Ocean (SW) monsoons. The resultant increase in river discharges at precession minima from both the Nile (and the wider Levant) resulted in the formation of sapropels in the eastern Mediterranean and is recorded as wet periods in speleothem deposits in the Soreq and Peqiin Caves of Israel. The predominant control of sedimentation on the late Pleistocene alluvial fans of southern Cyprus was climate.

Waters, J. V.; Jones, S. J.; Armstrong, H. A.

2010-03-01

136

Direct measurements of floodwater infiltration into shallow alluvial aquifers  

NASA Astrophysics Data System (ADS)

SummaryThe relationship between floodwater infiltration and groundwater recharge of a shallow alluvial aquifer in a hyper-arid desert was studied in the Arava valley, Israel. The study implemented an experimental system that simultaneously monitors all three hydrological domains controlling the recharge process: (1) floodwater stages on land surface, (2) water-content variations in the deep vadose zone, and (3) groundwater response to the infiltration. This experimental system makes use of a new technique for installing flexible time-domain reflectometry probes for continuous monitoring of the vadose zone moisture profiles. Water infiltration was monitored in controlled infiltration experiments and during a natural flood. The monitoring setup allowed real-time tracking of the wetting-front propagation velocities and assessment of water fluxes through the vadose zone. The results revealed a complex infiltration process that includes matrix and preferential flow together with lateral flow.

Dahan, Ofer; Shani, Yuval; Enzel, Yehouda; Yechieli, Yoseph; Yakirevich, Alex

2007-10-01

137

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

USGS Publications Warehouse

Ground-water recharge in the arid and semiarid southwestern United States results from the complex interplay of climate, geology, and vegetation across widely ranging spatial and temporal scales. Present-day recharge tends to be narrowly focused in time and space. Widespread water-table declines accompanied agricultural development during the twentieth century, demonstrating that sustainable ground-water supplies are not guaranteed when part of the extracted resource represents paleorecharge. Climatic controls on ground-water recharge range from seasonal cycles of summer monsoonal and winter frontal storms to multimillennial cycles of glacial and interglacial periods. Precipitation patterns reflect global-scale interactions among the oceans, atmosphere, and continents. Large-scale climatic influences associated with El Ni?o and Pacific Decadal Oscillations strongly, but irregularly, control weather in the study area, so that year-to-year variations in precipitation and ground-water recharge are large and difficult to predict. Proxy data indicate geologically recent periods of naturally occurring multidecadal droughts unlike any in the modern instrumental record. Any anthropogenically induced climate change will likely reduce ground-water recharge through diminished snowpack at higher elevations. Future changes in El Ni?o and monsoonal patterns, both crucial to precipitation in the study area, are highly uncertain in current models. Current land-use modifications influence ground-water recharge through vegetation, irrigation, and impermeable area. High mountain ranges bounding the study area?the San Bernadino Mountains and Sierra Nevada to the west, and the Wasatch and southern Colorado Rocky Mountains to the east?provide external geologic controls on ground-water recharge. Internal geologic controls stem from tectonic processes that led to numerous, variably connected alluvial-filled basins, exposure of extensive Paleozoic aquifers in mountainous recharge areas, and distinct modes of recharge in the Colorado Plateau and Basin and Range subregions. The chapters in this professional paper present (first) an overview of climatic and hydrogeologic framework (chapter A), followed by a regional analysis of ground-water recharge across the entire study area (chapter B). These are followed by an overview of site-specific case studies representing different subareas of the geographically diverse arid and semiarid southwestern United States (chapter C); the case studies themselves follow in chapters D?K. The regional analysis includes detailed hydrologic modeling within the framework of a high-resolution geographic-information system (GIS). Results from the regional analysis are used to explore both the distribution of ground-water recharge for mean climatic conditions as well as the influence of two climatic patterns?the El Ni?o-Southern Oscillation and Pacific Decadal Oscillation?that impart a high degree of variability to the hydrologic cycle. Individual case studies employ a variety of geophysical and geochemical techniques to investigate recharge processes and relate the processes to local geologic and climatic conditions. All of the case studies made use of naturally occurring tracers to quantify recharge. Thermal and geophysical techniques that were developed in the course of the studies are presented in appendices. The quantification of ground-water recharge in arid settings is inherently difficult due to the generally low amount of recharge, its spatially and temporally spotty nature, and the absence of techniques for directly measuring fluxes entering the saturated zone from the unsaturated zone. Deep water tables in arid alluvial basins correspond to thick unsaturated zones that produce up to millennial time lags between changes in hydrologic conditions at the land surface and subsequent changes in recharge to underlying ground water. Recent advances in physical, chemical, isotopic, and modeling techniques have foster

Edited by Stonestrom, David A.; Constantz, Jim; Ferre, Ty P.A.; Leake, Stanley A.

2007-01-01

138

Nitrate in Arid Basin Groundwater: How Historical Trends in Water Quality, Pumping Practices, and Land Use Inform our Understanding of Flow in these Systems  

NASA Astrophysics Data System (ADS)

During the past 60 years, an overall increase in nitrate (NO3-) concentration has been observed in basinal groundwaters of the Trans-Pecos region of West Texas. In wells where data from multiple decades are available (n = 60), 75% had an increase in NO3- concentration of greater than 1mg/L that appears largely independent of changes in salinity; some wells experienced an increase in NO3- and TDS while others experienced an increase in NO3- with no change or a decrease in TDS. These changes in water quality are rapid in comparison to previously estimated rates of recharge to these basins (~10,000 yrs). We infer that changes in land use and pumping practices over the past 6 decades are partially responsible for the observed changes in water quality and water level in the basin aquifers. In the summer of 2011, we collected water quality information (including NO3 and TDS) from approximately 80 wells in five basins located in the Trans-Pecos Region of West Texas; Red Light Draw, Lobo and Ryan Flats, Eagle Flats, Wild Horse and Michigan Flats, and the Northern Salt Basin. We have combined these data with past water quality data, water level monitoring, pumping records, and historical land use data (including historical aerial photographs and historical land cover data sets) to examine how anthropogenic effects have altered recharge, flow systems, and water quality in these basins over the past 60 years. We observe that the largest historical users of water in the region have water with some of the highest NO3- concentrations and the largest increases in NO3- during the period of examination; this indicates a potential anthropogenic source for (at least some of) the NO3- in the basin aquifers. Water tables have rebounded and salinity has decreased in areas of some basins where irrigated agriculture has been curtailed, though the trends in NO3- concentrations are less clear. These observations point to flow systems that are more preferentially permeable and more complex than is reflected in current groundwater models.

Robertson, W. M.; Sharp, J. M., Jr.

2011-12-01

139

Anthropogenic driven modern recharge and solute flux to arid basin aquifers: Results and implications for sustainability based on field observations and computational modeling  

NASA Astrophysics Data System (ADS)

Development of natural grass and scrubland for agricultural use (grazing and irrigated agriculture) has changed recharge mechanisms and raised questions about the sustainability of groundwater resources in the Trans-Pecos region of Texas. When quantifying the availability of water in the region, previous research relied upon the ';classic' conceptual model; minimal modern recharge, no widespread recharge on basin floors, and no recharge from anthropogenic sources such as irrigation return flow. Increasing nitrate (NO3-) concentrations in basin groundwater from the 1950's to present (median increase of 3-4 mg/L (as NO3-) over approximately 40 years) belie the model of limited modern recharge and pose a risk to water quality throughout the basins. We posit that grazing practices and irrigated agriculture have affected hydrologic processes in the basins by altering 1) the vegetation regime on the basin floors and 2) the magnitude and spatial distribution of infiltrating water. These impacts have increased recharge and transported Cl- and mobile nitrogen (N) from the vadose zone to the underlying groundwater. Using a spatially distributed net infiltration model, we estimate that between 7-20% of recharge occurring in the basins results from widespread recharge on the basin floors and that between 1960 and 2000 an additional 8.5 x 10^3 to 1.2 x 10^6 cubic meters of irrigation water has potentially been returned through irrigation return flow. Vadose zone cores collected from beneath land used for agricultural purposes document changes in water content and pore water chemistry that imply an increase in downward flux of moisture and solute resulting from human alteration of the natural system; reservoirs of NO3- and Cl- typically observed beneath the rooting depth of un-impacted vegetation are either displaced downward or flushed beyond the core depth under land with historical or ongoing irrigated agriculture. There are significant implications for the sustainability of groundwater resources in this system based upon the trends in groundwater NO3- concentrations, vadose zone core data, and results of the net infiltration models: 1) there may be more recharge to the basins than previously estimated and 2) there is a potential long-term concern for water quality. Due to the thick unsaturated zone in much of the system, long travel times are expected between the base of the root zone and the water table. It is unclear if the flux of NO3- and Cl- to the groundwater has peaked or if effects from the alteration of the natural vegetation regime will continue for years to come.

Robertson, W. M.; Sharp, J. M.

2013-12-01

140

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...

141

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

Microsoft Academic Search

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

1980-01-01

142

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

143

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

144

Guidelines for Determining Flood Hazards on Alluvial Fans.  

National Technical Information Service (NTIS)

Alluvial fans, and flooding on alluvial fans, show great diversity. This document provides an approach that considers site-specific conditions in the identification and mapping of flood hazards on alluvial fans.

2000-01-01

145

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

146

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

147

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

148

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

149

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

150

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

151

A physically-based sediment delivery model for arid regions  

Microsoft Academic Search

A sediment delivery model has been developed for estimating the sediment delivery rates in an arid upland basin. The model uses a steady- state sediment continuity equation and a first-order reaction model for deposition, since the initial potential sediment load is greater than the overland flow transport capacity—calculated by the Yalin method—in the arid regions. Spatial sediment delivery is analysed

K. D. SHARMA

1998-01-01

152

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

2014-05-28

153

Characterization of alluvial sources in the Owens Valley of eastern California using Fourier shape analysis  

SciTech Connect

Two-dimensional quartz grain shape was used to characterize sand grains from different source areas in the Owens Valley of eastern California. Combining a mathematical description of the grain outline and multivariate discriminant analysis, we have shown that quartz from clastic source rocks has a distinctive imprint when compared to samples from granitic, volcanic, or mixed fluvial source areas. Alternatively, quartz provided by a granitic source could equally well have been interpreted as if it were derived from any of the other sources considered. This study provides a standard of comparison for further analysis of sediment deposited in arid alluvial environments.

Wagoner, J.L.; Younker, J.L.

1982-03-01

154

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

155

An Alluvial Fan at Apollinaris Patera, Mars  

NASA Astrophysics Data System (ADS)

The large fan-like deposit at Apollinaris Patera, Mars, is demonstrated from Mola, Themis and Moc data to have an alluvial origin, indicating that active volcanism and a caldera lake coexisted for an extended period of time.

Ghail, R. C.; Hutchison, J. E.

2003-03-01

156

Input Data Formats for Alluvial Channel Experiments.  

National Technical Information Service (NTIS)

Various experiments covering hydraulic, morphologic and sediment characteristics of alluvial channels are being conducted on the Link Canals of Pakistan. Data from these experiments are to be punched on cards for use on digital computers. The formats have...

K. Mahmood T. Masood G. L. Eyster

1976-01-01

157

Impact and sustainability of low-head drip irrigation kits, in the semi-arid Gwanda and Beitbridge Districts, Mzingwane Catchment, Limpopo Basin, Zimbabwe  

NASA Astrophysics Data System (ADS)

Resource-poor smallholder farmers in the semi-arid Gwanda and Beitbridge districts face food insecurity on an annual basis due to a combination of poor and erratic rainfall (average 500 mm/a and 345 mm/a, respectively, for the period 1970-2003) and technologies inappropriate to their resource status. This impacts on both household livelihoods and food security. In an attempt to improve food security in the catchment a number of drip kit distribution programmes have been initiated since 2003 as part of an on-going global initiative aimed at 2 million poor households per year. A number of recent studies have assessed the technical performance of the drip kits in-lab and in-field. In early 2005 a study was undertaken to assess the impacts and sustainability of the drip kit programme. Representatives of the NGOs, local government, traditional leadership and agricultural extension officers were interviewed. Focus group discussions with beneficiaries and other villagers were held at village level. A survey of 114 households was then conducted in two districts, using a questionnaire developed from the output of the interviews and focus group discussions. The results from the study showed that the NGOs did not specifically target the distribution of the drip kits to poor members of the community (defined for the purpose of the study as those not owning cattle). Poor households made up 54% of the beneficiaries. This poor targeting of vulnerable households could have been a result of conditions set by some implementing NGOs that beneficiaries must have an assured water source. On the other hand, only 2% of the beneficiaries had used the kit to produce the expected 5 harvests over the 2 years, owing to problems related to water shortage, access to water and also pests and diseases. About 51% of the respondents had produced at least 3 harvests and 86% produced at least 2 harvests. Due to water shortages during the dry season 61% of production with the drip kit occurred during the wet season. This suggests that most households use the drip kits as supplementary irrigation. Conflicts between beneficiaries and water point committees or other water users developed in some areas especially during the dry season. The main finding from this study was that low cost drip kit programs can only be a sustainable intervention if implemented as an integral part of a long-term development program, not short-term relief programs and the programme should involve a broad range of stakeholders. A first step in any such program, especially in water scarce areas such as Gwanda and Beitbridge, is a detailed analysis of the existing water resources to assess availability and potential conflicts, prior to distribution of drip kits.

Moyo, Richard; Love, David; Mul, Marloes; Mupangwa, Walter; Twomlow, Steve

158

Changing Nitrate Concentrations in Arid Basin Aquifers- How Anthropogenic and Natural Processes Affect Water Quality and Availability in Trans-Pecos, TX  

NASA Astrophysics Data System (ADS)

For the past six decades nitrate concentrations in groundwater of the West Texas Bolson Aquifers have been increasing. Long-term records (from 1950 to present) indicate an average increase of 3-5 mg/L (as nitrate) with some wells increasing by over 40 mg/L within 1-2 decades. While irrigated agriculture is the second largest land use in the region (range land being the largest), isotopic analyses indicate that direct leaching of synthetic fertilizers is not a primary source of nitrate to the groundwater; the isotopic composition of the nitrate in the groundwater (delta 18-O of +2 to +10 per mil and delta 15-N of +6 to +13 per mil) is more similar to that of natural soil-derived nitrate in the region, or possibly manure-derived nitrate. Various anion ratios (chloride/bromide, nitrate/chloride, and nitrate/bromide) provide additional insight into the likely sources of groundwater nitrate and the mechanisms by which it is transported through the unsaturated zone; compared to atmospheric deposition, groundwater N/Cl and N/Br ratios appear to be relatively low, consistent with net N loss accompanied by relatively high delta 15-N of residual N. The observed decadal scale changes in groundwater nitrate concentration and presence of young (<70 year old) recharge (as measured using CFCs) are coincident with the growth of irrigated agriculture and intensive grazing within the basins. We hypothesize that past and present land use practices have contributed to the increase in nitrate in the groundwater in three ways; 1) plowing and grazing of previously undisturbed grasslands led to mobilization of soil nitrogen, 2) irrigation of crops has increased recharge beneath agricultural fields and mobilized naturally occurring nitrate from the unsaturated zone, and 3) deposition of manure by grazing animals may have contributed to high delta 15-N values, and in the case of now disused CAFO operations (confined feed lots) may have contributed locally to the total mass of reactive nitrogen. These effects are likely temporally and spatially variable, but have a substantial impact on strategies for addressing water quality and sustainability concerns in these basins and similar environments elsewhere.

Robertson, W. M.; Bohlke, J. K.; Sharp, J. M.

2012-12-01

159

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

160

Investigating Source to Sink Processes with Cosmogenic 10Be Concentrations in Multiple Alluvial Grain Sizes  

NASA Astrophysics Data System (ADS)

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 effect the interpretation of TCN concentrations in alluvium, and hence, the denudation rates and surface exposure ages derived from these data sets. We are using 10Be TCN concentrations in various alluvial sediment grain sizes to investigate the geomorphic processes responsible for eroding and transporting sediments from hillslopes, through drainage networks, and ultimately to sedimentary depocenters in two contrasting tectonic and climatic environments. The first is Red Wall Canyon in northern Death Valley, California, an arid tectonically active region. The second is the Blue Ridge Escarpment in the southern Appalachian Mountains, a humid tectonically inactive region. We collected sand (0.025-0.050 cm) and gravel (3-6cm) from active channels within the study areas for analysis of 10Be concentrations in the two distinct grain sizes; 19 samples were collected from Red Wall Canyon and 16 samples from the Blue Ridge Escarpment. By analyzing TCN concentrations in multiple alluvial grain sizes this project will explore the geomorphic processes responsible for transporting sediments from source area to depocenter, determine the geomorphic controls on TCN concentrations among variable grain size fractions in alluvial sediment, and ultimately help establish the most appropriate sample material for dating alluvial fans and measuring catchment-wide denudation rates.

Marstellar, T. L.; Frankel, K. L.; Belmont, P.

2010-12-01

161

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

162

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.

163

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

NASA Astrophysics Data System (ADS)

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 Electro-Magnetic (ATEM) methods were selected because they can be used to quickly survey large areas and with a great depth of investigation. Both helicopter and fixed-wing ATEM methods are available. A fixed-wing method (GEOTEM) was selected because of the potential for a depth of investigation of 300 m or more and because previous surveys indicated the method is useful in alluvial basins in southeastern Arizona. About 2,900 km of data along flight lines were surveyed across five alluvial basins, including the Middle San Pedro and Willcox Basins in southeastern Arizona, and Detrital, Hualapai, and Sacramento Basins in northwestern Arizona. Data initially were analyzed by the contractor (FUGRO Airborne Surveys) to produce conductivity-depth-transforms, which approximate the general subsurface electrical-property distribution along profiles. Physically based two-dimensional physical models of the profile data were then developed by PetRos- Eikon by using EMIGMA software. Hydrologically important lithologies can have different electrical properties. Several types of crystalline and sedimentary rocks generally are poor aquifers that have low porosity and high electrical resistivity. Good alluvial aquifers of sand and gravel generally have an intermediate electrical resistivity. Poor aquifer materials, such as silt and clay, and areas of poor quality water have low electrical resistivity values. Several types of control data were available to constrain the models including drill logs, electrical logs, water levels , and water quality information from wells; and gravity, seismic, direct-current resistivity, and transient-electromagnetic information from ground-based geophysical surveys. Results of the surveys will be used along with available subsurface information to describe the spatial extent of the alluvial aquifers and the general lithologic distribution within the alluvial aquifers.

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

2006-12-01

164

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

165

Timing and nature of alluvial fan and strath terrace formation in the Eastern Precordillera of Argentina  

NASA Astrophysics Data System (ADS)

Sixty-eight 10Be terrestrial cosmogenic nuclide (TCN) surface exposure ages are presented to define the timing of alluvial fan and strath terrace formation in the hyper-arid San Juan region of the Argentine Precordillera. This region is tectonically active, and numerous fault scarps traverse Quaternary landforms. The three study sites, Marquesado strath complex, Loma Negra alluvial fan and Carpintería strath complex reveal a history of alluvial fan and strath terrace development over the past ˜225 ka. The Marquesado complex Q3m surface dates to ˜17 ± 3 ka, whereas the Loma Negra Q1ln, Q2ln, Q3ln, Q4ln, and Q5ln surfaces date to ˜24 ± 3 ka, ˜48 ± 2 ka, ˜65 ± 13 ka, ˜105 ± 21 ka, and ˜181 ± 29 ka, respectively. The Carpintería complex comprises eight surfaces that have been dated and include the Q1c (˜23 ± 3 ka), Q2c (˜5 ± 5 ka), Q3ac (˜25 ± 12 ka), Q3bc (˜29 ± 15 ka), Q4c (˜61 ± 12 ka), Q5c (˜98 ± 18 ka), Q6c (˜93 ± 18 ka), and Q7c (˜212 ± 37 ka). 10Be TCN depth profile data for the Loma Negra alluvial fan complex and Carpintería strath terrace complex, as well as OSL ages on some Carpintería deposits, aid in refining surface ages for comparison with local and global climate proxies, and additionally offer insights into inheritance and erosion rate values for TCNs (˜10 × 10410Be atoms/g of SiO2 and ˜5 m Ma-1, respectively). Comparison with other alluvial fan studies in the region show that less dynamic and older preserved surfaces occur in the Carpintería and Loma Negra areas with only younger alluvial fan surfaces preserved both to the north and south. These data in combination with that of other studies illustrate broad regional agreement between alluvial fan and strath terrace ages, which suggests that climate is the dominant forcing agent in the timing of terrace formation in this region.

Hedrick, Kathryn; Owen, Lewis A.; Rockwell, Thomas K.; Meigs, Andrew; Costa, Carlos; Caffee, Marc W.; Masana, Eulalia; Ahumada, Emilio

2013-11-01

166

Hydrogeologic Behavior of an Alluvial Aquifer, Salta Province, Argentina: Simulations of Hydraulic Conductivity Field, Groundwater Flow, and Chloride Migration  

Microsoft Academic Search

This work was designed to analyze the hydrogeological behavior of an alluvial aquifer in the River Mojotoro basin site in the Province of Salta, Argentina. The study area presents coarse-grained sediments with high infiltration capacity. The hydraulic conductivity field is affected by the physical heterogeneity of the medium and a geostatistical method, kriging, was used to construct this field from

Jacqueline Köhn; Eduardo E. Kruse; Juan E. Santos

2002-01-01

167

Groundwater Recharge In Semi-Arid Regions Of India: An Overview Of Results Obtained Using Tracers  

NASA Astrophysics Data System (ADS)

Natural direct groundwater recharge was measured in the semi-arid/arid regions of India using techniques that employ environmental, geochemical, and artificial tracers. India is a sub-continent and has diverse hydrogeological and hydrometeorological conditions, including monsoon-type rainfall. Various geologic units were investigated, including unconsolidated, semiconsolidated, and consolidated materials and crystalline granitic/gneissic rocks. In the arid sands of Western Rajasthan and the semi-arid alluvial tracts of Gujarat, recharge rate is 3-10 percent (20-50 mm) of local average annual rainfall, whereas in the alluvial tracts of Uttar Pradesh, Punjab, and Haryana, recharge rates are about 12-20 percent (120-200 mm). The coastal semiconsolidated sandstone aquifers of Pondicherry and Neyveli have an average recharge rate of about 15-25 percent (200-300 mm). The consolidated aquifers, consisting of the basaltic and granitic-gneissic complexes, have a natural recharge rate of 3-15 percent (20-100 mm). Low values of recharge in Rajasthan and Gujarat are primarily due to arid conditions. The relatively high values of recharge to coastal aquifers are due to favourable hydrogeologic and climatic conditions. The weathered granitic and gneissic complexes of southern India have neither hydrogeological nor hydrometeorological factors in their favour, which accounts for their small recharge rates. The basaltic regions have intermediate recharge values (8-12 percent). Limited natural rainfall recharge and increased water use throughout the sub-continent calls for conservation as well as augmentation by artificial recharge techniques.

Sukhija, B. S.; Nagabhushanam, P.; Reddy, D. V.

1996-03-01

168

Facies analysis of tertiary alluvial fan deposits in the Jundiaí region, São Paulo, southeastern Brazil  

NASA Astrophysics Data System (ADS)

This article presents an analysis of facies of sedimentary sequences that occur as discontinuous bodies in the Jundiaí region, west of the main Tertiary continental basins of the southeastern Brazil continental rift. Nine identified sedimentary facies, grouped into four associations, suggest the existence of an ancient alluvial fan system whose source area was the Japi mountain range (Serra do Japi). The deposits are considered Tertiary in age and chronocorrelated with those identified in the Atibaia region and at other sites up to 100 km east and northeast of Jundiaí. The depositional model adopted to explain the filling of the basin proposes that the alluvial fans, which directly derive from the source area, terminated in a braided channel longitudinal to the basin axis that flowed to northwest, in a similar configuration to that of the present day. This basin may have extended to the Atibaia region or formed a set of small basins laterally contiguous to the faults associated with the rift. Such occurrences show that the formation of rift basins was broader than the area presently occupied by the main deposits.

Neves, M. A.; Morales, N.; Saad, A. R.

2005-09-01

169

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

170

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

171

Stable Isotopic Insights into Sedimentary Basin Evolution Along the Northern Tibetan Margin  

NASA Astrophysics Data System (ADS)

Oxygen isotopic data from 14 sections collected along the northern margin of Tibet show two distinct trends indicative of northward growth of the plateau in the Paleogene followed by basin isolation and growth of local mountain ranges in the Neogene. Our isotopic study encompass many of the large basins found north of Tibet including the Tarim, Qaidam, and Junggar basins, the Hexi Corridor, and basins in the Altun Shan. The oxygen isotopic results from paleosol, lacustrine, fluvial, and alluvial carbonate preserved in sedimentary basins show a general increase from the mid-Miocene to Recent, which we attribute to increased aridity as a result of basin isolation beginning in the Miocene. In contrast, in the Paleogene oxygen isotope values decrease with decreasing age within sections located along the northern margin of the plateau. We suggest that these decreases result from northward growth of Tibet and rearrangement of drainage patterns in the Paleogene. These isotopic stratigraphies provide records of the growth of adjacent ranges and segmentation of the landscape with this growth. Isotopic transects of basins perpendicular to the margin of the Tibetan orogen most likely support the growth of topography northwards through time. Additionally, isotopic gradients change with time, suggesting that each basin underwent a similar progression of climatic changes associated with the growth of topography. Isotopic records also vary depending on lithology sampled, and thus isotopic trends dependent on lithology are identified as well as regional isotopic trends. This study emphasizes the challenges of interpreting isotopic records in locales of extreme continentality, where isotopic records during known periods of surface uplift behave differently than predicted by models of isotopic distillation with elevation. To address these challenges, we have attempted to conduct spatially and temporally comprehensive sampling in this region, and have interpreted oxygen and carbon isotope stratigraphies in the context of available structural and thermochronological information.

Kent-Corson, M. L.; Ritts, B. D.; Charreau, J.; Zhuang, G.; Bovet, P. M.; Graham, S. A.; Chamberlain, P.

2008-12-01

172

Alluvial Pollen on the North China Plain  

NASA Astrophysics Data System (ADS)

Mordern alluvial pollen varies with geomorphic setting and depositional facies in sediments of the Yellow, Hutuo, and Luan rivers and in Baiyangdian and Hengshuihu lakes. Most of the arboreal pollen is derived from the mountains, whereas most of the nonarboreal pollen is derived from the plain itself. Alluvium dominated by Pinuspollen and Selaginellaspores was deposited during a flood. Hydrodynamic sorting of alluvial pollen exists in the sediments of floodplain, central bar, natural levees, and point bar. In reconstructing the ancient vegetation and past climate based on pollen in alluvium, it is important to consider sedimentary facies and geomorphologic setting.

Qinghai, Xu; Xiaolan, Yang; Chen, Wu; Lingyao, Meng; Zihui, Wang

1996-11-01

173

Spatiotemporal trends of aridity index in arid and semi-arid regions of Iran  

NASA Astrophysics Data System (ADS)

The spatiotemporal trends of aridity index in the arid and semi-arid regions of Iran in 1966-2005 were investigated using the Mann-Kendall test and Theil-Sen's slope estimator. The results of the analysis showed negative trends in annual aridity index at 55 % of the stations, while just one site had a statistically significant ( ? = 0.1) negative trend. Furthermore, the positive trends in the annual aridity index series were significant at the 95 % confidence level at Bushehr and Isfahan stations. The significant negative trend in the annual aridity index was obtained over Mashhad at the rate of -0.004. In the seasonal series, the negative trends in the spring and winter aridity index were larger compared with those in the other seasonal series. A noticeable decrease in the winter aridity index series was observed mostly in the southeast of the study area. In the summer and autumn aridity index, two significant positive trends were found.

Shifteh Some'e, B.; Ezani, Azadeh; Tabari, Hossein

2013-01-01

174

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

175

The paradox of large alluvial rivers (Invited)  

NASA Astrophysics Data System (ADS)

Large alluvial rivers exhibit large floodplains, very gentle slopes, a good selection of bed materials (generally sand), low specific stream power, and could represent the ultimate examples of “dynamic equilibrium” in fluvial systems. However, equilibrium can be discussed at different temporal scales. Base level changes by tectonic or climatic effects, modifications in sediment and water supply or different kinds of human impacts are the traditional causes that could trigger “disequilibrium” and changes in the longitudinal profile. Simultaneously, adjustments of longitudinal profiles were thought to be evolving from downstream to upstream by several processes, being the most common receding erosion. Some authors,have demonstrated that when changes in base level happen, a variety of adjustments can be reached in the lower course in function of the available sediment and water discharge, slopes articulations between the fluvial reach and the continental shelve, among others, and that the adjustments can be transferred upstream significantly in small rivers but not far upstream along large fluvial systems. When analyzing the Quaternary fluvial belts of large rivers in the millennium scale, paleohydrological changes and modifications in floodplain constructional processes or erosion, are associated normally to late Quaternary climatic changes. The study of several of the largest rivers demonstrates that climatic changes and fluvial responses are not always working totally in phase and those direct cause-consequences relations are not a rule. This paper describes floodplain evolution and the lagged geomorphic responses of some large river system to recent climatic changes. Information from some of the largest rivers of the world such as the Amazon, Parana, several tributaries of the Amazon (Negro, Xingú, Tapajos) as well as some large Siberian Rivers was used. Since the last deglaciation, these large fluvial systems have not had enough time to reach equilibrium conditions along whole the river and present several stages of “incomplete floodplains”. Furthermore, minor climatic changes during the Holocene have possibly also affected their fluvial style, producing additional and partial adjustments. A main concept presented here is that large rivers achieved equilibrium conditions mainly from upstream to downstream by partially filling up their valleys and local sedimentary basins/sediment sinks (e.g. wide valleys, flood basins and permanent water saturated floodplains, tectonic sunken blocks, among others) with a variety of morpho-sedimentological processes, and transferring equilibrium conditions from upstream to downstream. When the “available space” (sedimentary sink) becomes as full of sediments as possible, the rivers adjust on a more efficient corridor of channels in quasi-equilibrium conditions. Valley infilling processes progress downstream as a prograding system on areas of the channel-floodplain system that have not yet reached quasi-equilibrium conditions Because most results in the literature are focused on small to medium size rivers, these results intend to open a new discussion about floodplain mechanisms of construction, demystifying some traditional concepts relating floodplains and equilibrium, and climatic changes and river responses in large rivers.

Latrubesse, E. M.

2010-12-01

176

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

177

Detection and Mapping of Sedimentary Features on Alluvial Fans Using High-Resolution Overhead Thermal Imaging  

NASA Astrophysics Data System (ADS)

In this study we evaluate the utility of thermal imagery for revealing geomorphic features and evidence of sedimentary processes on the surfaces of alluvial fans. Prior studies of alluvial fans have made extensive use of visible imagery and traditional field-based mapping techniques to identify surface geomorphic features and sedimentary processes. Here we present a comparison of features mapped using thermal images acquired from the ground, a light aircraft (altitude ~5000 ft, resolution ~2 m/pixel) and ASTER satellite imagery (resolution 90 m/pixel), to a preexisting ground-based map of features on an example alluvial fan in Owens Valley, California. Thermal images from a light aircraft were acquired at several times of day to determine how the surface temperatures of the alluvial fan rise and fall throughout a diurnal cycle. We have also acquired thermal images of the same fan from the ground at 5 minute intervals over the course of a full diurnal cycle. ASTER thermal data also covers the Owens Valley, and was used to determine if this technique can be used from orbit at significantly lower resolution (90 m/pixel). In an arid climate with low vegetation cover, the temperature of a surface at any given time of day is a complex function of many parameters, including slope, azimuth, composition, degree of induration, and grain size. By analyzing the temperatures on the surface of an alluvial fan with comparable slopes, azimuth, and composition, we make estimates of the relative particle size or degree of induration. We utilize the fact that several sedimentary processes acting on the surface of alluvial fans sort particles by size. For example, both debris flow and channelized flow processes can form linear features of large and small clasts. Therefore, thermal imagery could be expected to reveal evidence of these processes at the surfaces of alluvial fans in the form of spatial patterns of surface thermal properties. Process-related sedimentary features, such as clast-rich and clast-poor debris flows, debris-flow levees, and the change in particle size at the toe of the fan are all clearly revealed in the aerial thermal images of the Dolomite Fan in Owens Valley, California. The locations of these features in the thermal imagery match the locations of the features as mapped using traditional ground-based field sedimentology techniques by Blair and McPherson (1998). All debris flows that are exposed at the fan surface are evident in the aerial thermal imagery, including those that have been heavily weathered and are difficult to observe in visible aerial or orbital imagery. ASTER satellite thermal image data does not show the same sedimentary features as our aerial thermal images, presumably due to the significantly poorer spatial resolution of the satellite data. Our aerial thermal imagery suggests that higher resolution satellite data from a future satellite experiment could be used to detect sedimentary processes on alluvial fans anywhere on Earth. High resolution thermal imagery from above can be used to provide preliminary reconnaissance of an alluvial fan, suggest what processes have most recently acted on the surface of the fan, and to prioritize sites for detailed study on the ground. Future work will expand our database of alluvial fans and the list of process-related surface features that can be identified with thermal imagery.

Hardgrove, C. J.; Moersch, J. E.; Whisner, S.

2008-12-01

178

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

179

Soil Carbonate Dynamics on Arid Cropland in North China  

NASA Astrophysics Data System (ADS)

Pedogenic carbonate (PIC) is an important element for carbon sequestration. However, field data necessary to quantify carbon sequestration as carbonate have been lacking. Here, we report recent studies of carbonate accumulation in soils of the arid and semi-arid regions of north China. First study was carried out in southern Xinjiang, the Yanqi Basin, where more than 100 soil samples were collected from desert land, shrub land and cropland, and soil organic carbon (SOC) and inorganic carbon (SIC) and their stable 13C compositions were determined. This study showed that both SOC and SIC stocks were significantly higher on the cropland than on the desert land and shrub land. Our analyses suggested that cropping might have led to large PIC accumulation (24-116 g C m-2 year-1) in the Yanqi Basin. Second study was to evaluate carbon sequestration on cropland using archived soil samples from three long-term experiment (LTE) sites in north China: Urumqi, Yangling and Zhengzhou. SOC and SIC, and their stable 13C compositions were determined in two sets of soil samples (130 samples in total) collected in the early and late 2000's under various fertilization treatments. Our study showed an overall increase of SIC content in soil profiles over time, particularly under fertilizations. Accumulation rate of SIC stock over the 0-100 cm ranged from ~100 to 200 g C m-2 year-1, with the greatest rate found under the highest fertilization rate. Our analyses indicated that fertilization might have led to an average accumulation rate of > 60 g C m-2 year-1 for PIC on these arid croplands. Our studies showed that more carbon sequestrated in the form of carbonate than as SOC on arid and semi-arid lands, and suggests that increasing SOC stock through straw incorporation and manure application in the arid and semi-arid regions would also enhance carbonate accumulation in soil profiles over long-term.

Wang, X.; Xu, M.; Wang, J.; Zhang, W.; Yang, X.; Huang, S.; Liu, H.

2013-12-01

180

Tectonic controls on the morphometry of alluvial fans around Danehkhoshk anticline, Zagros, Iran  

NASA Astrophysics Data System (ADS)

Alluvial fans are important landforms where their morphology and morphometry reflect changes in tectonic, climate, base level, and drainage basin characteristics. Along the margins of tectonically active mountain ranges like the Zagros Mountains, alluvial fans are generally assumed to act as useful landforms for identifying the level of tectonic activity. The purpose of this paper is to evaluate the relationship between active tectonics and morphometric characteristics of alluvial fans around Danehkhoshk anticline in the Simply Folded Belt of Zagros. Morphometric characteristics of alluvial fans, such as area (FA), slope (SF) length of base (BF), width/length ratio (W/L), radius (R), sweep angle (SA) and entrenchment (E) as well as valley floor width-to-height ratio (Vf) and strata dips of anticline limbs (DAL), were measured. The study area was sub-divided into eight tectonic zones and then the mean values of the above-mentioned parameters were calculated in each zone. Result reveals that values of SA, BF and E are directly proportional to DAL. The poor relationships between catchment characteristics (slope and area) and fan parameters are probably due to extensive karstic landforms of catchments having complex hydrologic systems and, hence, result in complex catchment/fan relations. The highly entrenched fans with high sweep angles and long bases are characteristic of tectonically active fronts of Danehkhoshk anticline, having V-shaped valleys (higher Vf values), steep triangular facets and more rotated limbs (higher DAL values). Apart from the tectonic control on fan development, the fan head entrenchment and negative accumulation spaces on most alluvial fans can be attributed to decreased sediment load and discharge the drier the present-day climate regime.

Bahrami, Shahram

2013-01-01

181

UNESCO's G-WADI Program - Developing and Delivering Tools for Improved Water Management in Semi-arid and Arid Lands  

NASA Astrophysics Data System (ADS)

UNESCO's Water and Development Information for Arid Lands - A Global Network (G-WADI) aims to strengthen the capacity to manage the water resources of arid and semi-arid areas around the globe through a network of international and regional cooperation. Six centers, including SAHRA headquartered at the University of Arizona and CHRS at UC-Irvine, are cooperating to improve water resource management by sharing knowledge and tools. Specific objectives include: improved understanding of the special characteristics of hydrological systems and water management needs in arid areas, through shared data and experiences; capacity building of individuals and institutions; raising awareness of advanced technologies for data provision, data assimilation, and system analysis; and promoting integrated basin management and the use of appropriate decision support tools. SAHRA coordinates G-WADI's information dissemination via G-WADI's web site and publications. Web-based resources include Global Water News Watch and the subscription service, Water News Tracker, plus access to remotely sensed precipitation data from HyDIS. Information on use of isotopes and chemical tracers is also featured. Materials and outcomes from various workshops and short courses on modeling, water harvesting, and impacts of climate change also are provided. While the intent is to benefit water resource managers in semi- arid and arid developing countries, the collaboration among international water centers, and perspectives and traditional knowledge gained from users, has benefitted U.S. researchers in many ways.

Woodard, G. C.; Imam, B.; Sorooshian, S.

2007-12-01

182

Longitudinal profiles in simple alluvial systems  

NASA Astrophysics Data System (ADS)

Theoretical considerations suggest that exponential or quadratic functions are apt for describing the longitudinal profiles of aggrading, alluvial systems that are unaffected by significant lateral inputs of water or sediment. A new set of field data confirms this for individual sedimentary links along a wandering gravel-bed river in British Columbia, Canada. Each link is viewed as a simple alluvial system, without major water or sediment inputs, within which grain size typically fines downstream in a relatively systematic manner. Such homogeneous reaches are suitable for the investigation of simple profile form. It is found that quadratic approximations are the most flexible descriptor for link longitudinal profiles. Overall, the river forms an irregularly cuspate long profile structured by these fundamental length-scale units. Both link gradients and link fining rate reflect size-selective aggradation associated with the bounding lateral inputs.

Rice, Stephen P.; Church, Michael

2001-02-01

183

Interaction of fine sediment with alluvial streambeds  

USGS Publications Warehouse

An alluvial streambed can have a large capacity to store fine sediments that are extracted from the flow when instream concentrations are high and it can gradually release fine sediment to the flow when the instream concentrations are low. Several types of storage mechanisms are available depending on the relative size distribution of the suspended load and bed material, as well as the flow hydraulics. -from Authors

Jobson, H. E.; Carey, W. P.

1989-01-01

184

Punctuated aridity in southern Africa during the last glacial cycle: The chronology of linear dune construction in the northeastern Kalahari  

Microsoft Academic Search

The Mega Kalahari of central southern Africa is one of the most extensive Quaternary desert basins. On a regional scale, present-day aeolian activity is restricted to episodic dune crest reactivation in the most arid southwestern desert core. There is, however, abundant evidence of former periods of both more arid and more humid conditions, many of which have little or no

S. Stokes; G. Haynes; D. S. G. Thomas; J. L. Horrocks; M. Higginson; M. Malifa

1998-01-01

185

Geospatial Data to Support Analysis of Water-Quality Conditions in Basin-Fill Aquifers in the Southwestern United States  

USGS Publications Warehouse

The Southwest Principal Aquifers study area consists of most of California and Nevada and parts of Utah, Arizona, New Mexico, and Colorado; it is about 409,000 square miles. The Basin-fill aquifers extend through about 201,000 square miles of the study area and are the primary source of water for cities and agricultural communities in basins in the arid and semiarid southwestern United States (Southwest). The demand on limited ground-water resources in areas in the southwestern United States has increased significantly. This increased demand underscores the importance of understanding factors that affect the water quality in basin-fill aquifers in the region, which are being studied through the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) program. As a part of this study, spatial datasets of natural and anthropogenic factors that may affect ground-water quality of the basin-fill aquifers in the southwestern United States were developed. These data include physical characteristics of the region, such as geology, elevation, and precipitation, as well as anthropogenic factors, including population, land use, and water use. Spatial statistics for the alluvial basins in the Southwest have been calculated using the datasets. This information provides a foundation for the development of conceptual and statistical models that relate natural and anthropogenic factors to ground-water quality across the Southwest. A geographic information system (GIS) was used to determine and illustrate the spatial distribution of these basin-fill variables across the region. One hundred-meter resolution raster data layers that represent the spatial characteristics of the basins' boundaries, drainage areas, population densities, land use, and water use were developed for the entire Southwest.

McKinney, Tim S.; Anning, David W.

2009-01-01

186

Water-quality assessment of the Carson River ground-water basin, Nevada and California; project description  

USGS Publications Warehouse

In April 1986, the U.S. Geological Survey began a pilot program to assess the quality of the nation 's surface water and groundwater resources. This program, called the National Water-Quality Assessment (NAWQA) program, is designed to acquire and interpret information about a wide range of water quality issues. The program is in its early stages and consists of four surface water and three groundwater pilot projects. The objectives of the Carson River basin NAWQA project are described in the context of the national program, the study area and its associated water quality issues, and a proposed study approach. The objectives of the Carson River basin NAWQA project are to: (1) investigate regional groundwater quality; (2) describe relations of groundwater quality to land use, geohydrology, and other pertinent factors; (3) provide a general description of the location, nature and possible causes of selected widespread water quality problems in the project area; and (4) develop new techniques for characterizing regional groundwater quality, especially in arid alluvial basins. There are to be three major phases of the Carson River basin project. The first will consist of compilation and analysis of existing data. The second phase will consist of a regional water quality survey that will produce a consistent set of data that can be used to: (1) define regional quality of groundwater within the Carson River basin; and (2) compare that water quality with other aquifers in the Nation. The third phase will include topical studies that will define groundwater quality in the Carson River basin with respect to certain constituents, either basin wide or within specific areas of concern. (Lantz-PTT)

Welch, A. H.; Plume, R. W.

1987-01-01

187

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

188

Accumulation of salt-rich dust from Owens Lake playa in nearby alluvial soils  

NASA Astrophysics Data System (ADS)

Over the last 100 years, Owens Lake playa in eastern California has been one of the largest point sources of PM-10 dust in the United States. Here we evaluate the spatial impact of the salt-rich playa dust on the alluvial piedmont soils of Owens Valley with the expectation that those nearest the playa will have the highest concentrations of playa-derived salts. We sampled soils of similar age on alluvial fans derived from Sierra Nevada granites along the valley axis to determine soluble salt and specific ion concentrations. Salt concentrations are indeed highest in those soils most proximate to the playa, with higher levels of sodium and elevated pH. However, one site directly north of the playa has significantly higher salt concentrations as measured by electrical conductivity (EC) compared to all other soils sampled, an average pH of about 10 and a sodium adsorption ratio (SAR) greater than 15, suggesting a strong impact of local dust as a result of local topography and wind patterns. Although EC, pH, and SAR of other sampled soils fall into normal ranges for sandy granitic soils in a semi-arid climate, the soils closer to the playa show greater salt and sodium impact than those further away. The strong local impact of playa salts and the patterns of salt contribution away from the playa suggest a spatial effect of dust on the alluvial soils that will grow both in intensity of impact and in distance from the playa if dust fluxes remain at recent levels.

Quick, Dayna J.; Chadwick, Oliver A.

2011-06-01

189

Luminescence chronology of river adjustment and incision of Quaternary sediments in the alluvial plain of the Sabarmati River, north Gujarat, India  

Microsoft Academic Search

River adjustment and incision in the Sabarmati basin, Gujarat, India have been examined at a site near Mahudi. Towards this, the morphostratigraphy and depositional chronometry of the middle alluvial plains were investigated. The upper fluvial sequence, along with the overlying aeolian sand and riverbed scroll plains, provide clues to the evolution of the present Sabarmati River. Sedimentological analyses of the

Pradeep Srivastava; Navin Juyal; Ashok K Singhvi; Robert J Wasson; Mark D Bateman

2001-01-01

190

Controls on alluvial fan long-profiles  

USGS Publications Warehouse

Water and debris flows exiting confined valleys have a tendency to deposit sediment on steep fans. On alluvial fans where water transport of gravel predominates, channel slopes tend to decrease downfan from ???0.10-0.04 to ???0.01 across wide ranges of climate and tectonism. Some have argued that this pattern reflects grain-size fining downfan such that higher threshold slopes are required just to entrain coarser particles in the waters of the upper fan, whereas lower slopes are required to entrain finer grains downfan (threshold hypothesis). An older hypothesis is that slope is adjusted to transport the supplied sediment load, which decreases downfan as deposition occurs (transport hypothesis). We have begun to test these hypotheses for alluvial fan long-profiles using detailed hydraulic and particle-size data in sediment transport models. On four alluvial fans in the western U.S., we find that channel hydraulic radiiare largely 0.5-0.9 m at fan heads, decreasing to 0.1-0.2 m at distal margins. We find that median gravel diameter does not change systematically along the upper 60%-80% of active fan channels as slope declines, so downstream gravel fining cannot explain most of the observed channel slope reduction. However, as slope declines, channel-bed sand cover increases systematically downfan from areal fractions of <20% above fan heads to distal fan values in excess of 70%. As a result, entrainment thresholds for bed material might decrease systematically downfan, leading to lower slopes. However, current models of this effect alone tend to underpredict downfan slope changes. This is likely due to off-channel gravel deposition. Calculations that match observed fan long-profiles require an exponential decline in gravel transport rate, so that on some fans approximately half of the load must be deposited off channel every -0.20-1.4 km downfan. This leads us to hypothesize that some alluvial fan long-proffies are statements about the rate of overbank deposition of coarse particles downfan, a process for which there is currently no mechanistic theory. ?? 2007 Geological Society of America.

Stock, J. D.; Schmidt, K. M.; Miller, D. M.

2008-01-01

191

CHANNEL EVOLUTION IN MODIFIED ALLUVIAL STREAMS.  

USGS Publications Warehouse

This study (a) assesses the channel changes and network trends of bed level response after modifications between 1959 and 1972 of alluvial channels in western Tennessee and (b) develops a conceptual model of bank slope development to qualitatively assess bank stability and potential channel widening. A six-step, semiquantitative model of channel evolution in disturbed channels was developed by quantifying bed level trends and recognizing qualitative stages of bank slope development. Development of the bank profile is defined in terms of three dynamic and observable surfaces: (a) vertical face (70 to 90 degrees), (b) upper bank (25 to 50 degrees), and (c) slough line (20 to 25 degrees).

Simon, Andrew; Hupp, Cliff, R.

1987-01-01

192

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

193

Macro-roughness model of bedrock-alluvial river morphodynamics  

NASA Astrophysics Data System (ADS)

The 1-D saltation-abrasion model of channel bedrock incision of Sklar and Dietrich, in which the erosion rate is buffered by the surface area fraction of bedrock covered by alluvium, was a major advance over models that treat river erosion as a function of bed slope and drainage area. Their model is, however, limited because it calculates bed cover in terms of bedload sediment supply rather than local bedload transport. It implicitly assumes that as sediment supply from upstream changes, the transport rate adjusts instantaneously everywhere downstream to match. This assumption is not valid in general, and thus can give rise unphysical consequences. Here we present a unified morphodynamic formulation of both channel incision and alluviation which specifically tracks the spatiotemporal variation of both bedload transport and alluvial thickness. It does so by relating the cover fraction not to a ratio of bedload supply rate to capacity bedload transport, but rather to the ratio of alluvium thickness to a macro-roughness characterizing the bedrock surface. The new formulation predicts waves of alluviation and rarification, in addition to bedrock erosion. Embedded in it are three physical processes: alluvial diffusion, fast downstream advection of alluvial disturbances and slow upstream migration of incisional disturbances. Solutions of this formulation over a fixed bed are used to demonstrate the stripping of an initial alluvial cover, the emplacement of alluvial cover over an initially bare bed and the advection-diffusion of a sediment pulse over an alluvial bed. A solution for alluvial-incisional interaction in a channel with a basement undergoing net rock uplift shows how an impulsive increase in sediment supply can quickly and completely bury the bedrock under thick alluvium, so blocking bedrock erosion. As the river responds to rock uplift or base level fall, the transition point separating an alluvial reach upstream from an alluvial-bedrock reach downstream migrates upstream in the form of a "hidden knickpoint". A solution for the case of a zone of rock subsidence (graben) bounded upstream and downstream by zones of rock uplift (horsts) yields a steady-state solution that is unattainable with the original saltation-abrasion model. A solution for the case of bedrock-alluvial coevolution upstream of an alluviated river mouth illustrates how the bedrock surface can be progressive buried not far below the alluvium. Because the model tracks the spatiotemporal variation of both bedload transport and alluvial thickness, it is applicable to the study of the incisional response of a river subject to temporally varying sediment supply. It thus has the potential to capture the response of an alluvial-bedrock river to massive impulsive sediment inputs associated with landslides or debris flows.

Zhang, L.; Parker, G.; Stark, C. P.; Inoue, T.; Viparelli, E.; Fu, X.; Izumi, N.

2014-05-01

194

Management of Arid Lands: An Agenda for Research.  

National Technical Information Service (NTIS)

Characteristics of arid lands, arid lands under stress, and issues in arid lands policy are considered. The inherent environmental variability of arid lands and the modes of adaptation evolved by arid lands peoples are discussed. Forces effecting rapid ch...

H. Ingram R. Nichols A. Gault P. Rosenfield

1978-01-01

195

Estimating mountain block recharge to downstream alluvial aquifers from standard methods  

NASA Astrophysics Data System (ADS)

SummaryThe purpose of the study is to assess the applicability in estimating the mountain block recharge (MBR) to the downstream alluvial aquifers in the sub-tropical area using baseflow separation and rainfall infiltration methods. The Choushui-Wu River basin, the largest groundwater region in Taiwan was the study area. The high slope mountainous catchment located in the upstream of Choushui-Wu River basin, act as an important conduit in conveying surface and subsurface runoff to the recharge of the downstream alluvial aquifers. Geographic Information Systems (GISs) was applied to facilitate the estimation processes. The estimated MBR using the baseflow separation method was 1.08 × 109 m3/year of which Wu River and Choushui River basins comprised 0.27 × 109 m3/year (25.2%) and 0.81 × 109 m3/year (74.8%), respectively. These results are similar to the previous O18 isotopic study indicating that 22% and 78% were from the Wu River and Choushui River basins, respectively. Moreover, the estimated amount of lateral flow using C14 technique from the upstream of Choushui River basin was 0.83 × 109 m3/year, which is close to the result (0.81 × 109 m3/year) of this study. For comparison, groundwater recharged by rainfall infiltration in the mountainous catchment was derived from the precipitation, evapotranspiration, land use and soil types of the region. The estimated MBR by the rainfall infiltration method is 1.06 × 109 m3/year, which is close to 1.08 × 109 m3/year determined by the baseflow separation method. These results are also similar to the groundwater hydrograph analysis. The proposed methods show simple and efficient computation and do not require complex hydrological modeling and detailed knowledge of soil characteristics. They can reasonably estimate the lateral boundary influx contributing from the MBR and are thus applicable to estimate the MBRs in other sub-tropical regions.

Kao, Yu-Hsuan; Liu, Chen-Wuing; Wang, Sheng-Wei; Lee, Cheng-Haw

2012-03-01

196

Design of flood protection for transportation alignments on alluvial fans  

Microsoft Academic Search

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

1991-01-01

197

Late Cenozoic tectonic activity and its significance in the Northern Junggar Basin, Northwestern China  

NASA Astrophysics Data System (ADS)

The Dingshan area located in the northern part of the Junggar Basin of northwestern China is a significant prospect area for sandstone-type uranium deposits in China, where mainly Cenozoic rocks were deposited. The Cenozoic strata can be divided into four units according to the prior data and our own field observation. Sedimentary studies indicate that most Cenozoic strata were deposited under a hot and arid climate in a continental environment. The sedimentary facies are alluvial-fan, meandering-fluvial, and fluvio-lacustrine. Field investigation and interpretation of satellite images suggest that Cenozoic tectonics in the area is characterized by reactivation of early deep-seated thrusts, resulting in extensional fractures and formation of many small depressions in the shallow crustal level. Measurement of joint orientations suggests that regional shortening direction trends in north-south in the middle Pleistocene as indicated by the ESR (Electronic Spin Resonance) age of 0.1-0.4 Ma obtained from fault gouge and gypsum deposits. A four-stage sedimentation-tectonic evolution model of the northern Junggar Basin during the Late Cenozoic can be established based on reconstruction of sedimentary filling processes and Cenozoic tectonic movements. We suggest that landform evolution and groundwater movement are controlled by active tectonics, indicating that Late Cenozoic tectonic activities may also play important roles in the formation of sandstone-type uranium deposits. Therefore, a new metallogenic model for sandstone-type uranium deposits is proposed.

Chen, Zhengle; Liu, Jian; Gong, Hongliang; Han, Fengbin; Briggs, Stephanie Marion; Zheng, Enjiu; Wang, Guo

2011-01-01

198

Mapping Quaternary Alluvial Fans in the Southwestern United States based on Multi-Parameter Surface Roughness of LiDAR Topographic Data  

NASA Astrophysics Data System (ADS)

Quaternary alluvial fans, common landforms in hyper- to semi-arid regions, have diverse surface morphology, desert varnish accumulation, clasts rubification, desert pavement formation, soil development, and soil stratigraphy. Their age and surface topographic expression vary greatly within a single fan between adjacent fans. Numerous studies have demonstrated that the surface expression and morphometry of alluvial fans can be used as an indicator of their relative age of deposition, but only recently has there been an effort to utilize high resolution topographic data to differentiate alluvial fans with automated and quantifiable routines We developed a quantitative model for mapping the relative age of alluvial fan surfaces based on a multi-parameter surface roughness computed from 1-meter resolution LiDAR topographic data. Roughness is defined as a function of scale of observation and the integration of slope, curvature (tangential), and aspect topographic parameters. Alluvial fan roughness values were computed across multiple observation scales (3m×3m to 150m×150m moving observation windows) based on the standard deviation (STD) of slope, curvature, and aspect. Plots of roughness value versus size of observation scale suggest that the STD of each of the three topographic parameters at 7m×7m observation window best identified the signature of surface roughness elements. Roughness maps derived from the slope, curvature, and aspect at this scale were integrated using fuzzy logic operators (fuzzy OR and fuzzy gamma). The integrated roughness map was then classified into five relative morpho-stratigraphic surface age categories (active wash to ~400 ka) and statistically compared with a similar five-fold surface age map of alluvial fans developed using traditional field surveys and aerial photo interpretation. The model correctly predicted the distribution and relative surface age of ~61% of the observed alluvial fan map. The results of the multi-parameter model imply that the first order roughness elements of alluvial fan surfaces have the average wavelength of 7m, and the roughness contributed by these elements decreases with the age of alluvial fans.

Regmi, N. R.; McDonald, E.; Bacon, S. N.

2012-12-01

199

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

200

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

201

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

202

Evolution of Devonian alluvial systems in an oblique-slip mobile zone—an example from the Broken River Province, northeastern Australia  

NASA Astrophysics Data System (ADS)

The lower 1500 m of the Late Devonian Bulgeri Formation was deposited in a tectonically active foreland basin in response to a major Late Devonian orogeny in the Broken River Province, northeastern Australia. The basin was bounded to the east by an uplifted belt of Palaeozoic sedimentary and volcanic rocks that was deformed east of an active thrust zone (Gray Creek Fault). To the south, the basin was bounded by igneous and metamorphic basement rocks, uplifted along a major oblique-slip fault zone (Clarke River Fault). Facies analysis and mapping of alluvial stratigraphy has resulted in the recognition of compositionally distinct, coalescing, axial and transverse alluvial drainage systems. The axial drainage system flowed to the northeast, approximately parallel to the Gray Creek Fault and away from the Clarke River Fault. The system drained the cratonic basement to the south and west, and accumulated mainly feldspathic and quartzose sediments. A lower, fine-grained succession, and an upper coarse-grained succession are recognised. The lower succession ('Rockfields' alluvial system) was deposited in broad, sandy, low-sinuosity channels and semi-permanent floodplain lakes. These rivers drained ultimately northward into a retreating coastal plain and shallow sea that lay over the Georgetown Province. The upper succession ('Bulgeri' alluvial system) was deposited in gravelly and sandy braided rivers emanating from south of the Clarke River Fault. The transverse distributary system ('Stopem Blockem' alluvial system), accumulated mainly lithic, coarse-grained sediments deposited in gravelly braided rivers sourced from the uplifted orogenic belt to the east. These rivers flowed towards the northwest before coalescing with the axial drainage system where they changed to a northerly orientation. Uplifted fault blocks of Devonian limestone within the basin locally contributed limestone gravel to these rivers. Between the coalescing axial and transverse river systems lay extensive floodplains, which received a slow, but compositionally mixed supply of mainly fine-grained sediments. Long periods of weathering resulted in the development of reddened palaeosols, with well developed calcrete horizons. The palaeogeography and fluvial style of the lower Bulgeri Formation is compared to the Gulf of Carpentaria in northeastern Australia. Analysis of the architecture of these alluvial systems has led to recognition of at least three, subsidence-driven, tectonic cyclothems and this is supported by simple quantitative modelling. The lower part of each cycle begins with a thin conglomeratic succession above an unconformity, and is overlain by thick, relatively fine-grained, syn-tectonic alluvial facies deposited during maximum subsidence. The upper part of each cycle is marked by increasingly coarse-grained, post-tectonic alluvial facies. These were deposited by gravel progradation following cessation of uplift or thrusting in the source areas and concomitant slowing of subsidence rates.

Lang, Simon C.

1993-05-01

203

Late Cretaceous to Mid-Tertiary Basin Evolution in the Central Tibetan Plateau: Changing Environments in Response to Tectonic Partitioning, Aridification, and Regional Elevation Gain  

NASA Astrophysics Data System (ADS)

Located in the Bangong-Nujiang suture (BNS) between the Lhasa and Qiangtang terranes of central Tibet, the Nima basin records Cretaceous through Late Miocene sediment accumulation during a period of drastically changing paleogeography, paleoclimate, and paleoelevation. The BNS formed during Latest Jurassic-Early Cretaceous time as the Lhasa terrane collided with the Qiangtang terrane. During Early to mid-Cretaceous time the region was located at or below sea level. By Aptian time (115 Ma), Nima basin was above sea level and strongly influenced by local volcanic activity and crustal shortening in the reactivated BNS zone. In the southern Nima basin, a roughly 50 Myr (Late Cretaceous through Paleocene) depositional hiatus correlates with significant crustal shortening and ensuing voluminous ignimbrite eruptions in the Lhasa terrane. In the northern Nima basin, deposition continued during latest Cretaceous time, recording arid paleoclimate in evaporitic lacustrine and eolian dunefield deposits. By Oligocene time the Nima basin comprised two depocenters accumulating coarse-grained alluvial, fluvial, lacustrine (evaporitic) and fan-delta deposits in close association with reactivated thrusts in the BNS zone. Stable carbon and oxygen isotopic data indicate that climate was arid and regional paleoelevation during the Late Oligocene was about 4.7 km, as it is today. Overall the Nima basin depositional record, combined with structural and geochronological studies, demonstrates that the BNS was reactivated during mid-Cretaceous and mid-Tertiary time, that the intervening 50 Myr interval was a time of regional upper crustal shortening in the Lhasa terrane followed by widespread ignimbrite eruptions, and that arid paleoclimate and high paleoelevation were established by Late Cretaceous and Late Oligocene time, respectively. Within the context of other data sets from the Lhasa terrane, the Nima record is consistent with low-angle subduction of Neotethyan oceanic lithosphere during Early Cretaceous time, followed by shortening within the Gangdese retroarc and northern Lhasa terrane thrust belts during mid- Cretaceous to early Tertiary time (105 to 50 Ma), accompanied, but also outlasted, by lithospheric delamination/dripping and regional magmatic flare-up during latest Cretaceous through Eocene time, followed by underthrusting of Indian lower crust and lithosphere as far north as the BNS during Late Oligocene time.

Decelles, P. G.; Kapp, P.

2006-12-01

204

Deglacial Flood Origin of the Charleston Alluvial Fan, Lower Mississippi Alluvial Valley  

NASA Astrophysics Data System (ADS)

Large-magnitude flooding of the Mississippi River from proglacial lakes Agassiz and Superior most likely occurred between 11,300 and 10,900 and 9900 and 9500 yr B.P. The Charleston alluvial fan, a depositional remnant of one of these floods, is located at the head of a wide alluvial plain near Charleston, Missouri. The fan is an elongate, convex-up sand body (16 × 24 km) composed of medium- and fine-grained sand at least 8 m thick. This sand contrasts with the older coarse-grained sand of the braided stream surface to the west and south and younger silty clay of the meandering stream level to the north and east. A weakly developed soil separates the underlying braided steam deposits from the alluvial fan. A bulk-soil radiocarbon date of 10,590 ± 200 yr B.P. from the contact between the fan and clays of the meandering stream system indicates that the Charleston fan was deposited near the end of the early interval of flooding from Lake Agassiz about 10,900 yr B.P. If the Charleston fan is the last remnant of deglacial flooding in the lower Mississippi Valley, then deposition of significant quantities of sediment from largemagnitude floods between 10,000 and 9500 yr B.P. did not extend into the lower Mississippi Valley through Thebes Gap.

Porter, Donna A.; Guccione, Margaret J.

1994-05-01

205

Annual plants in arid and semi-arid desert regions  

Microsoft Academic Search

Annual plants are the main vegetation in arid and semi-arid desert regions. Because of their unique traits, they are the optimal\\u000a experimental subjects for ecological studies. In this article, we summarize annual plants’ seed germination strategies, seedling\\u000a adaptability mechanism to environments, seed dispersal, and soil seed banks. We also discuss the biotic and abiotic factors\\u000a affecting the composition and dynamics

Xuehua Li; Xiaolan Li; Deming Jiang; Zhimin Liu; Qinghe Yu

2008-01-01

206

Chloride mass-balance method for estimating ground water recharge in arid areas: Examples from western Saudi Arabia  

USGS Publications Warehouse

The chloride mass-balance method, which integrates time and aerial distribution of ground water recharge, was applied to small alluvial aquifers in the wadi systems of the Asir and Hijaz mountains in western Saudi Arabia. This application is an extension of the method shown to be suitable for estimating recharge in regional aquifers in semi-arid areas. Because the method integrates recharge in time and space it appears to be, with certain assumptions, particularly well suited for and areas with large temporal and spatial variation in recharge. In general, recharge was found to be between 3 to 4% of precipitation - a range consistent with recharge rates found in other arid and semi-arid areas of the earth.

Bazuhair, A. S.; Wood, W. W.

1996-01-01

207

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

208

Modeling the Surface Water-Groundwater Interaction in Arid and Semi-Arid Regions Impacted by Agricultural Activities  

NASA Astrophysics Data System (ADS)

In many semi-arid and arid regions, interaction between surface water and groundwater plays an important role in the eco-hydrological system. The interaction is often complicated by agricultural activities such as surface water diversion, groundwater pumping, and irrigation. In existing surface water-groundwater integrated models, simulation of the interaction is often simplified, which could introduce significant simulation uncertainty under certain circumstance. In this study, GSFLOW, a USGS model coupling PRMS and MODFLOW, was improved to better characterize the surface water-groundwater interaction. The practices of water diversion from rivers, groundwater pumping and irrigation are explicitly simulated. In addition, the original kinematic wave routing method was replaced by a dynamic wave routing method. The improved model was then applied in Zhangye Basin (the midstream part of Heihe River Baisn), China, where the famous 'Silk Road' came through. It is a typical semi-arid region of the western China, with extensive agriculture in its oasis. The model was established and calibrated using the data in 2000-2008. A series of numerical experiments were conducted to evaluate the effect of those improvements. It has been demonstrated that with the improvements, the observed streamflow and groundwater level were better reproduced by the model. The improvements have a significant impact on the simulation of multiple fluxes associated with the interaction, such as groundwater discharge, riverbed seepage, infiltration, etc. Human activities were proved to be key elements of the water cycle in the study area. The study results have important implications to the water resources modeling and management in semi-arid and arid basins.

Tian, Y.; Wu, B.; Zheng, Y.

2013-12-01

209

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

210

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

211

Comparison of three evapotranspiration models to Bowen ratio-energy balance method for a vineyard in an arid desert region of northwest China  

Microsoft Academic Search

The accurate determination of vineyard evapotranspiration (ET) in the arid desert region of northwest China is important for allocating irrigation water and improving water use efficiency. Taken a vineyard at the Shiyang river basin of the Hexi corridor of Gansu Province as an example, this study evaluated the applicability of the Bowen ratio-energy balance (BREB) method in the arid desert

Baozhong Zhang; Shaozhong Kang; Fusheng Li; Lu Zhang

2008-01-01

212

ROLES OF NATURAL LEVEES ON THE ARA RIVER ALLUVIAL FAN  

NASA Astrophysics Data System (ADS)

For the comprehensive flood control measures for alluvial fans, it is required to understand the effects of natural levees and micro-topography on reducing flood damages. We investigate the role of natural levees in the flood control measures for the alluvial fan of the Ara River by mapping historical community development and using the hazard maps.As a result, it is clarified that many communities have been developed on natural levees, and that natural levees are resistant to spreading of flood waters. The above indicates the significance of researches on natural levees and micro-topography as control measures on alluvial fans.

Saito, Shigeru; Fukuoka, Shoji

213

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

214

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

215

Long-term interactions between man and the fluvial environment - case of the Diyala alluvial fan, Iraq  

NASA Astrophysics Data System (ADS)

The Mesopotamian alluvial plain is dominated by large aggradading river systems (the Euphrates, Tigris and their tributaries), which are prone to avulsions. An avulsion can be defined as the diversion of flow from an existing channel onto the floodplain, eventually resulting in a new channel belt. Early civilizations depended on the position of rivers for their economic survival and hence the impact of channel shifts could be devastating (Wilkinson 2003; Morozova 2005; Heyvaert & Baeteman 2008). Research in the Iranian deltaic part of the Mesopotamian plain has demonstrated that deliberate human action (such as the construction of irrigation canals and dams) triggered or obstructed the alluvial processes leading to an avulsion on fluvial megafans (during preconditioning, triggering and post-triggering stages) (Walstra et al. 2010; Heyvaert et al. 2012, Heyvaert et al.2013). Thus, there is ample evidence that the present-day alluvial landscapes in the region are the result of complex interactions between natural and anthropogenic processes. Here we present a reconstruction of the Late Holocene evolution of the Diyala alluvial fan (one of the main tributaries of the Tigris in Iraq), with particular attention to the relations between alluvial fan development, changes in channel pattern, the construction of irrigation networks and the rise and collapse of societies through historic times. The work largely draws on the use of remote sensing and GIS techniques for geomorphological mapping, and previously published archaeological field data (Adams 1965). By linking archaeological sites of known age with traces of ancient irrigation networks we were able to establish a chronological framework of alluvial activity of the Diyala alluvial fan. Our results demonstrate that centralized and technologically advanced societies were able to maintain a rapidly aggradading distibutary channel system, supplying water and sediment across the entire alluvial fan. As a consequence, during these periods (Parthian, Sasanian and again in modern times), significant human modification of the landscape took place. Periods of societal decline are associated with reduced human impact and the development of a single-threaded incising river system. Adams, R.M. (1965). Land behind Baghdad: A history of settlement on the Diyala plains. University of Chicago Press, Chicago, Illinois. Heyvaert, V.M.A. & Baeteman, C. (2008). A Middle to Late Holocene avulsion history of the Euphrates river: a case study from Tell ed-D-er, Iraq, Lower Mesopotamia. Quaternary Science Reviews, 27, 2401-2410. Heyvaert, V. M. A., Walstra, J., Verkinderen, P., Weerts, H. J. T. & Ooghe, B. (2012). The role of human interference on the channel shifting of the river Karkheh in the Lower Khuzestan plain (Mesopotamia, SW Iran). Quaternary International, 251, 52-63. Heyvaert, V.M.A., Walstra, J., Weerts, H.J.T. (2013). Human impact on avulsion and fan development in a semi-arid region: examples from SW Iran. Abstractbook of the 10th International Fluvial Sedimentology Conference, July 2013,Leeds, United Kingdom. Morozova, G.S. (2005). A review of Holocene avulsions of the Tigris and Euphrates rivers and possible effects on the evolution of civilizations in lower Mesopotamia. Geoarchaeology, 20, 401-423. Walstra, J., Heyvaert, V. M. A. & Verkinderen, P. (2010). Assessing human impact on alluvial fan development: a multidisciplinary case-study from Lower Khuzestan (SW Iran). Geodinamica Acta, 23, 267-285. Wilkinson, T.J. (2003). Archaeological Landscapes of the Near East. The University of Arizona Press, Tucson, Arizona.

Heyvaert, Vanessa M. A.; Walstra, Jan; Mortier, Clément

2014-05-01

216

Mass balance from alluvial fan isopachs: a case study from the Chinese Tian Shan  

NASA Astrophysics Data System (ADS)

Continental surfaces are incessantly reworked through erosion and sedimentation. Markers of erosion within drainage areas are often scarce and temporary, but at the outlet of mountain belts, more continuous and perennial records of deposition can be found in alluvial fans. These fans are constructed by the deposition through time of the coarse part of sediments transported by rivers. Volume of sediments trapped in alluvial fans can then be used in order to reconstruct sediment fluxes coming out from their catchment areas and the associated erosion rates. Quantifying such erosion rates is of great interest for the study of mass transfer. It is also necessary to understand relief dynamics, as well as the influence of tectonic and climate on this dynamics. We propose here a complete method to estimate erosion fluxes from alluvial fans in a specific area, the northern piedmont of the Tian Shan in China. Along the piedmont of this range, series of fans of different ages are clearly identified. In particular, abandoned fans (which were active before 10 000 years ago) are well preserved in the landscape, and easily identifiable on satellite images. These fans have been deeply incised during the last deglaciation (about 10 000 years ago), and therefore, their basal surface can be observed. In this specific area, it is then possible to obtain field constraints on the real fan thickness. First, we draw a morpho-sedimentary map of the fans and their drainage basins. Then, we went on the field to estimate the fan thickness wherever it is possible. Finally, based on this data set, and on geometrical considerations, we built isopach maps of the fans and calculate their volumes. These 3D reconstructions can then be compared to the geometrical relationships classically used to assess alluvial fan volumes from their upper surface only. Erosion rates of ten drainage basins can be derived from these volumes, allowing a sink to source investigation, for the period of fan activity. In north Tian Shan, these erosion rates can be compared with other values calculated from bedload measurements and cosmogenic data, providing thus an opportunity to discuss results coming from different methods

Guerit, Laure; Barrier, Laurie; Métivier, François; Jolivet, Marc; Fu, Bihong

2013-04-01

217

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

218

Environmental impacts on the hydrology of ephemeral streams and alluvial aquifers  

NASA Astrophysics Data System (ADS)

In arid and semi-arid regions alluvial groundwater resources of ephemeral streams are highly important for water supplies and ecosystems. Recent projects have studied processes of indirect recharge in situ and in detail (Dahan et al., 2008; Klaus et al., 2008). Still, little is known about the vulnerability of these aquifers to environmental impacts like surface dam constructions, land-use changes and climatic conditions as well as the time and type of response to such external impacts. With a catchment size of about 30.000 km² the Swakop River in Namibia is the largest of the country's twelve major ephemeral streams draining westwards into the Atlantic Ocean. The alluvial groundwater resources have been affected by the construction of two major surface water dams in the upper catchment as well as by abstractions for rural water supply, farming and mining downstream of the constructed dams (referred to as lower catchment). The determination of environmental impacts in the Swakop River catchment is difficult due to scarce hydrometric and water quality data. In order to obtain a better understanding of the hydrological system under changing environmental conditions a spatially distributed environmental tracer approach was applied. A longitudinal profile of groundwater samples was taken within a field study along the alluvial aquifer of the Swakop River. The samples were analysed for stable isotopes (18O, 2H), major ions and trace elements as well as for the residence time indicators CFC and SF6. The combined application of groundwater residence time analysis, stable isotope measurements and hydrochemical characterisation was used in order to associate a time scale with groundwater quality data. This method provides dated information on recharge and water quality before and after dam construction and can be used to detect environmental impacts on the hydrological system. CFC-12 analysis resulted in recharge years ranging from 1950 (0.01 pmol/l) to 1992 (1.4 pmol/l). Seven of 14 groundwater samples represent mainly groundwater recharged before or between the construction of surface water dams (1970 and 1978), the remaining samples represent groundwater recharge after dam construction. The groundwater residence time is generally short (recharge mainly after 1980) in the upper catchment and much higher (recharge mainly before 1980 and before dam construction) in the lower part of the catchment. Combining the age and isotope information shows how the surface water dams modified the pattern of groundwater recharge. The lower catchment has been partly cut off from the upper part in terms of indirect groundwater recharge by floods which means that most large floods originating in the headwaters of the Swakop River do not reach the lower alluvial aquifer anymore. The relationship between groundwater age and groundwater constituents helped to define baselines of hydrological properties (origin of water, recharge altitude) and of hydrochemical composition prior to the construction of dams (and other anthropogenic impacts). The well defined relationship between groundwater age and altitude of the river further helps to assess how fast different segments will be affected by these environmental impacts. References Dahan, O., Tatarsky, B., Enzel, Y., Kuells, C., Seely, M., Benito, G. (2008) Dynamics of Flood Water Infiltration and Ground Water Recharge in Hyperarid Desert. Ground Water, Vol. 46, 3. (6-2008), pp. 450-461. Klaus, J., Kuells, C., Dahan, O. (2008): Evaluating the recharge mechanism of the Lower Kuiseb Dune Area using mixing cell modeling and residence time data. Journal of Hydrology, v. 358, p. 304-316.

Kuells, C.; Marx, V.; Bittner, A.; Ellmies, R.; Seely, M.

2009-04-01

219

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

220

Optimal alluvial channel width under a bank stability constraint  

NASA Astrophysics Data System (ADS)

To properly predict alluvial channel width using rational regime models, an analysis of bank stability must be included in the model. When bank stability is not considered, optimizations assuming maximum sediment transport capacity (MTC) typically under-predict alluvial channel width for natural and laboratory streams. Such discrepancies between regime model predictions and observed channel widths have been used to argue that optimizations such as MTC do not describe the behaviour of alluvial systems. However, rational regime models that explicitly consider bank stability exhibit no such bias and can predict alluvial channel widths quite accurately. We present an analysis of both laboratory and natural alluvial channels, using both kinds of models, and demonstrate the importance of bank stability in constraining optimization solutions. We also identify a scale effect, whereby the effect of vegetation on bank strength declines as the absolute scale of the system increases. We argue that comparisons of alluvial channel widths against predictions from rational regime models unconstrained by bank stability are inappropriate, because they introduce a known and quantifiable bias (toward under-prediction by the model) due to the absence of a bank stability constraint.

Eaton, Brett C.; Millar, Robert G.

2004-09-01

221

Ecotonal Control on Vadose-Zone Fluxes in Arid Regions Over Very Long Time Scales  

Microsoft Academic Search

Recent studies indicate that vegetation plays an important role in regulating recharge in semiarid and arid basins over very long time scales. Several lines of evidence from desert floor environments in the southwestern United States suggest that vegetation has established essentially permanent upward hydraulic gradients, effectively precluding diffuse recharge since the transition from woodland to xeric scrub in the early

F. M. Phillips; M. A. Walvoord; R. Sandvig

2003-01-01

222

Sensitivity of riparian ecosystems in arid and semiarid environments to moisture pulses  

Microsoft Academic Search

Structural and functional dynamics of riparian vegetation in arid and semiarid basins are controlled by hydrological processes operating at local, landscape and catchment scales. However, the importance of growing-season precipitation as a control on evapotranspiration (ET) and carbon cycling in these ecosystems varies considerably across the riparian landscape, depending largely on access to the near-surface water table. Here we describe

D. G. Williams; R. L. Scott; T. E. Huxman; D. C. Goodrich; G. Lin

2006-01-01

223

Boundary Layer Circulations Driven by Land Surface Contrasts within an Arid Environment  

Microsoft Academic Search

This talk will illustrate the variety of locally forced PBL circulations that are driven by heterogeneities in the land surface within an arid environment. The presenter will use observations and MM5 model data from a study done within the Great Basin Desert (or Great Salt Lake Desert), located to the southwest o Salt Lake City, Utah. This region is characteristic

D. Rife

2006-01-01

224

Chemistry of Coalbed Methane Discharge Water Interacting with Semi-arid Ephemeral Stream Changes  

Microsoft Academic Search

The objective of this study was to examine the chemistry of Coalbed Methane (CBM) discharge water reacting with semi-arid ephemeral stream channels in the Powder River Basin, Wyoming. The study area consisted of two ephemeral streams: Burger Draw and Sue Draw. These streams are tributaries to the perennial Powder River. Samples were collected bimonthly from three CBM discharge points and

Marji; J. Patz; Katta J. Reddy; Quentin D. Skinner

2004-01-01

225

ARID1B is a specific vulnerability in ARID1A-mutant cancers.  

PubMed

Recent studies have revealed that ARID1A, encoding AT-rich interactive domain 1A (SWI-like), is frequently mutated across a 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, an ARID1A homolog whose gene product is mutually exclusive with ARID1A in SWI/SNF complexes, as the number 1 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 in both cancer cells and primary cells. We also find that ARID1A and ARID1B are frequently co-mutated in cancer but that ARID1A-deficient cancers retain at least one functional 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

2014-03-01

226

Research on land degradation in arid and semi-arid zone: a case of Hebei Province  

Microsoft Academic Search

Land degradation is the most important environmental issue facing arid and semi-arid region, affecting regional land sustainable development. This article analyzed land degradation in Hebei province of China located in arid and semi-arid region with TM images of 1991 and 2000, and 1991 to 2000 land use change surveying data. Based on RS and GIS, comprised with statistic methods, land

Chunyan Lv; Zhenrong Yu; Yunzhe Cao

2006-01-01

227

New crops for arid lands.  

PubMed

Five plants are described that could be grown commercially under arid conditions. Once the most valuable component has been obtained from each plant (rubber from guayule; seed oil from jojoba, buffalo gourd, and bladderpod; and resin from gumweed), the remaining material holds potential for useful products as well as fuel. It is difficult to realize the full potential of arid land plants, however, because of the complexities of developing the necessary agricultural and industrial infrastructure simultaneously. To do so, multicompany efforts or cooperative efforts between government and the private sector will be required. PMID:17770060

Hinman, C W

1984-09-28

228

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

229

From source to sink in the sediment cascade of the Hei-River Basin: Implications for late Quaternary landscape dynamics in the Gobi Desert, NW China  

NASA Astrophysics Data System (ADS)

The Hei River Basin with a catchment size of ~130,000 km² is host to one of the largest continental alluvial fans in the world. The basin comprises: (1) its high-elevated river sources in the glacier and the permafrost zone of the Qilian Mountains, (2) the semi-arid foreland of the Hexi Corridor in the middle reaches and (3) the endorheic Ejina Basin (Gaxun Nur Basin) as its recent sink. The river basin is characterized by small subcatchments of hyper-arid mountain ranges of the Gobi-Tienshan and Beishan as well as of smooth and fuzzy water divides of the Hexi-Corridor and the Badain Jaran Sand Sea. Up to 300 m of Quaternary sediments establish the large Ejina Basin, with a size of 28,000 km², as an excellent archive for environmental reconstructions located at the recent intersection of westerly and monsoonal air masses. Three sediment cores (up to 230 m long) provide evidence of sedimentation dynamics over the last 250,000 years, and cover at least two terminations since OIS 6. The sediments have to be regarded as a result of the interplay between tectonic activity and climate dynamics, accompanied by a related eolian and hydrological response of the catchment. Thus, it is crucial to understand and reconstruct the sedimentary processes along the huge sediment cascades, and to identify the most important sediment sources. Here we present a provenance analysis from mineralogical fingerprints of modern sediments that have been deposited along recent pathways from the sources to the Ejina Basin. The methodical approach combines the analysis of clay minerals, bulk mineralogy, and bulk geochemistry. Furthermore, we use heavy mineral data obtained from automated particle-analysis via a computer-controlled scanning electron microscope (CCSEM) and XRD measurements. We analyzed ~200 surface samples from the whole catchment as reference material, as well as the upper 19 m of cored sediments, to gain insight into temporal changes of depositional processes and provenance. Geostatistical analyses of the compositional data reveal a clear discrimination between sediments from the Qilian Shan in the south and from local basin sediments in the north. Moreover the mineralogical fingerprints allow the differentiation of sources from intrusive rocks that are dominant in the Bei Shan mountain sub-catchment, and from greenschist-bearing metamorphic rocks, that are widespread in the Qilian Mountain catchment. Finally, we draw conclusions about the main transport processes and pathways from assumed source regions to the sink (Ejina Basin). The provenance analysis of the sediment core reveals strong changes from local (Bei Shan) to long-distant (Qilian Shan) sources. The Late Pleistocene record reveals frequently changing sediment supply between periodic high mountain runoff and local episodic runoff. We assume that these variations are related to basin internal processes (e.g. fan dynamics, tectonics) and changing environmental conditions that are linked with variations in meltwater runoff and precipitation in the upper reaches of the southern catchment. These conclusions are supported by grain size characteristics that indicate phases of predominant alluvial activity and limnic deposition around the Late Glacial to Holocene transition and enhanced pre-Holocene eolian activity.

Schimpf, Stefan; Nottebaum, Veit; Diekmann, Bernhard; Hartmann, Kai; Lehmkuhl, Frank; Wünnemann, Bernd; Zhang, Chi

2014-05-01

230

Facies analysis and tectonic significance of lacustrine fan-deltaic successions in the Pliocene–Pleistocene Mugello Basin, Central Italy  

Microsoft Academic Search

The Mugello Basin is an intermontane asymmetric basin, trending WNW–ESE and filled with Pliocene–Pleistocene alluvial and lacustrine deposits. The study focuses on the sedimentary succession deposited at the basin's northern margin and uses facies analysis to reconstruct the margin's depositional and deformation history. The controversial concepts of “fan delta” and “hyperconcentrated flow,” adopted in this study, are firstly discussed. The

Marco Benvenuti

2003-01-01

231

A landscape-scale study of land use and parent material effects on soil organic carbon and total nitrogen in the Konya Basin, Turkey  

NASA Astrophysics Data System (ADS)

In ecosystems where intensive farming and grazing have been occurring for millennia, there is poor understanding of how present-day soil biogeochemical properties relate to factors associated with soil parent materials (e.g. texture, mineralogy), and the net effects of long-term land use practices. Soil organic carbon (SOC) and total soil nitrogen (TN) are important for their roles in maintaining soil structure, moisture, fertility and contributing to carbon sequestration. Our research used a state factor approach (Jenny 1981) to study effects of soil parent materials and land use practices on SOC, TN, and other properties across thirty-five sites in the Konya Basin, an arid region in south-central Turkey farmed and grazed for over 8,000 years. This project is one of the first to study land use impacts on soils at a landscape scale (500 km2) in south-central Turkey, and incorporate geospatial data (e.g. a satellite imagery-derived land cover map we developed) to aid selection of field sites. Focusing on the plough layer (0-25cm) in two depth intervals, we compared effects of agriculture, orchard cultivation and grazing land use practices and clay-loam alluvial, sandy-loam volcanic and lacustrine clay soils on soil properties using standard least squares regression analyses. SOC and TN depended strongly on parent materials, but not on land use. Averaged across both depth intervals, alluvial soil SOC and TN concentrations (19.4 ± 1.32 Mg/ha SOC, 2.86 ± 1.23 Mg/ha TN) were higher and significantly different than lacustrine (9.72 ± 3.01 Mg/ha SOC, 1.57 ± 0.69 Mg/ha TN) and volcanic soil concentrations (7.40 ± 1.72 Mg/ha SOC, 1.02 ± 0.35 Mg/ha TN). Land use significantly affected SOC and TN on alluvial soils, but not on volcanic or lacustrine soils. Our results demonstrate the potential for land use to have different effects on different soils in this region. Our data on SOC, TN and other soil properties illustrate patterns in regional SOC and TN variability not shown by previous modeling or soil survey efforts. We provide baseline information on SOC and TN that can inform benchmarks for future soil monitoring and land use planning in an arid region that is likely to be highly impacted by future climatic changes, agricultural intensification and urban development. Our results suggest the importance of accounting for soil physical properties, and land use effects that are dependent on soil parent materials in future efforts to model or account for SOC and TN in similar ancient agricultural landscapes.

Mayes, M. T.; Marin-Spiotta, E.; Ozdogan, M.; Erdogan, M. A.

2011-12-01

232

Conduits to Catchments: Deformation Band Faults in Arid and Semi-Arid Vadose Zone Sands  

NASA Astrophysics Data System (ADS)

Where fault movement intercepts sandy sediments, deformational processes create narrow, tabular zones of reduced pore and grain sizes, called deformation band faults, which possess markedly different hydraulic properties than the parent sands. These faults are commonly found where tectonic extension and erosion have combined to create basins containing variably lithified, heterolithic sediments, which in turn form thick vadose and saturated zones. Under arid or semi-arid conditions the unsaturated property differences between these faults and their poorly lithified parent sands appear to be large enough that the faults can potentially act as paths for preferential flow and transport, or as liquid phase catchments, depending on the conditions. We measured the unsaturated hydraulic properties of three small-displacement normal faults and adjacent sands found in the Bosque del Apache Wildlife Refuge, central New Mexico, USA using UFA centrifuge systems. Fits to commonly used unsaturated property models revealed consistent differences between sands and faults. Analytical one-dimensional models of steady infiltration, exfiltration, and solute transport confirm that faults can become paths for preferential flow and transport. Under dry conditions and observed fault spatial densities, faulted sands can infiltrate and exfiltrate orders of magnitude more liquid phase water than unfaulted sands. Solute residence times are two to four orders of magnitude shorter through faulted than unfaulted sand beds and diagenetic alteration is far more likely to occur in faults than sands because faults are predicted to transmit as many as 10 4 pore volumes in the time needed to transmit a single pore volume through the sand. Numerical modeling of steady two dimensional downwards flow near a dipping fault suggests that, under relatively wet conditions, faults with sufficiently low dip angles can intercept enough water to form sizeable zones of increased water content in the hanging wall. These wetter zones can act as fast paths for subsequent water or solute pulses. Deformation band faults can thus act as catchments under relatively wet vadose zone conditions and as conduits under much drier conditions. In either case, faults can significantly increase water and solute transport through sandy beds in arid and semi-arid vadose zones.

Sigda, J. M.; Wilson, J. L.; Goodwin, L. B.; Conca, J. L.

2002-12-01

233

Geohydrology of the alluvial and terrace deposits of the North Canadian River from Oklahoma City to Eufaula Lake, central Oklahoma  

USGS Publications Warehouse

This investigation was undertaken to describe the geohydrology of the alluvial and terrace deposits along the North Canadian River between Lake Overholser and Eufaula Lake, an area of about 1,835 square miles, and to determine the maximum annual yield of ground water. A 1982 water-level map of the alluvial and terrace aquifer was prepared using field data and published records. Data from test holes and other data from the files of the U.S. Geological Survey and the Oklahoma Water Resources Board were used to establish the approximate thickness of the alluvial and terrace deposits. The North Canadian River from Lake Overholser, near Oklahoma City, to Eufaula Lake is paralleled by a 2- to 3-mile wide band of alluvium. Scattered terrace deposits on either side of the alluvium reach an extreme width of 8 miles. Rocks of Permian age bound the alluvial and terrace deposits from the west to the midpoint of the study area; Pennsylvanian rocks bound the alluvial and terrace deposits from that point eastward. Three major aquifers are present in the study area: the alluvial and terrace aquifer, consisting of alluvium and terrace deposits of Quaternary age in a narrow band on either side of the North Canadian River; the Garber-Wellington aquifer of Permian age, consisting of an upper unconfined zone and a lower confined zone separated by relatively impermeable shales; and the Ada-Vamoosa aquifer of Pennsylvanian age. At locations were the alluvial and terrace aquifer overlies either of the other aquifers, there is hydraulic continuity between the alluvial and terrace aquifer and the other aquifers, and water levels are the same. Most large-scale municipal and industrial pumping from the Garber-Wellington aquifer is from the lower zone and has little discernible effect upon the alluvial and terrace aquifer. The total estimated base flow of the North Canadian River for the studied reach is 264 cubic feet per second. Evapotranspiration from the basin in August is about 60 cubic feet per second for the North Canadian River from Lake Overholser to a measuring station above Eufaula Lake. Estimated recharge rates to the alluvial and terrace aquifer in the basin range from 1.7 inches at the west edge of the study area to 7.0 inches at the east edge. Total permitted withdrawal from the aquifer, according to records of the Oklahoma Water Resources Board, ranged from 2,107 acre-feet per year in 1942 to about 21,415 acre-feet per year in 1982. Simulations of the alluvial and terrace aquifer from Lake Overholser to Eufaula Lake were made using a finite-difference model developed by McDonald and Harbaugh (1984). The area of the aquifers was subdivided into a finite-difference grid having 30 rows and 57 columns with cells measuring 1 mile in the north-south direction and 2 miles in the east-west direction. The model was calibrated in two steps: A steady-state calibration simulated head distribution prior to extensive pumping of the aquifer in 1942, and a transient calibration simulated head distribution after extensive pumpage. The final horizontal hydraulic conductivity used for the alluvial and terrace aquifer was 0.0036 feet per second (310 feet per day) at all locations. The recharge rate for the alluvial and terrace aquifer ranged from 1.7 inch per year in the west to 7.0 inches per year in the east, and averaged about 3.3 inches per year. A specific yield of 15 percent was used for the transient simulation. Permitted pumpage for 1942 through 1982 was used in the digital model to estimate the annual volume of water in storage in the alluvial and terrace aquifer for the years for this time period. The 1982 permitted pumpage rates were used for projections for 1983 to 2020. The estimated volume of water in storage was 1,940,000 acre-feet in 1982. Because the estimated recharge rate is equal to the allowed pumpage rate in 1982, the projected volume of water in storage in both 1993 and 2020 was 1,890,000 acre-feet.

Havens, J. S.

1989-01-01

234

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

235

Late Neogene and Quaternary alluvial fans give evidence for tectonic events at the eastern margin of the Eastern Alps  

NASA Astrophysics Data System (ADS)

The deposition of Neogene and Quaternary alluvial sediments along the southwestern margin of the Vienna Basin record significant tectonic events for the eastern margin of the Alps. After the early to middle Miocene marine sedimentation phase fresh-water environments prevailed in the Vienna Basin during the Pannonian (Lake Pannon). Unconformably above early to middle Pannonian sediments, a late Pannonian to Pliocene conglomerate succession, the Rohrbach Formation, was deposited, followed by Pleistocene gravels of the Mitterndorf basin. The Rohrbach Formation builds a fan-like sedimentary body from the southwestern margin of the Vienna Basin near Neunkirchen up to the city of Wiener Neustadt, where these conglomerates occur within a depth of about 40 m below Pleistocene gravels. Outcrops of these probably Pliocene (Dacian) conglomerates have been investigated at the quarry Rohrbach. Conglomerates are mainly coarse to fine-grained, crudely bedded, and display maximum particle sizes up to 10 cm. Erosive fluvial channels with dimensions from 1 to several meters are present. Sandstone intercalations are common and sometimes graded. Laterally extensive silt- and claystones layers are present in minor amounts. Clasts include mainly limestones, dolomites and sandstones, and minor amounts of mica schists, gneisses and quartzites. Heavy minerals are dominated by garnet, epidote and stable minerals like tourmaline. Minor amounts of chrome spinel and higher metamorphic minerals like kyanite and sillimanite are present in most of the samples. The Rohrbach Formation is interpreted as an alluvial fan-braided river system fed by source areas mainly in the Northern Calcareous Alps and subsidiary source areas in the Greywacke Zone and the Austro-Alpine basement units. Synsedimentary deformations may point to the activity of basin margin faults during the Pliocene/Dacian. After a stable and tectonically quiet period, subsidence in the Pleistocene Mitterndorf basin started around ~ 250.000 yrs BP. Subsidence created accommodation for alluvial fans (Piesting Fan, Schwarza Fan), which filled the basin and unconformably overly the Rohrbach Formation. Calculated maximum subsidence rates show values of ~ 0.7 mm/yr, largely corresponding to recent precise leveling values of around -1 mm/yr for that area. Although the stratigraphic architecture of the fans is largely controlled by climate cycles (Salcher et al., in press), the development of these mountain front alluvial fans calls for a renewed phase of tectonism which is still active today. As evidenced by pebble composition and heavy mineral assemblages the source areas for the fans are largely similar to that of the Rohrbach Formation. Our investigations thus point to two significant phases of Late Neogene to Quaternary tectonism at the eastern margin of the Eastern Alps: A first tectonic phase in the Dacian (early Pliocene, ca. 5.3 - 4.6 Ma, but starting in late Pannonian) resulted in sedimentation of the Rohrbach Formation, a second phase in the Middle to Late Pleistocene resulted in subsidence of the Mitterndorf subbasin and formation of mountain front alluvial fans.

Wagreich, M.; Salcher, B.; Koukal, V.

2009-04-01

236

Exome sequencing reveals frequent inactivating mutations in ARID1A, ARID1B, ARID2 and ARID4A in microsatellite unstable colorectal cancer.  

PubMed

ARID1A has been identified as a novel tumor suppressor gene in ovarian cancer and subsequently in various other tumor types. ARID1A belongs to the ARID domain containing gene family, which comprises of 15 genes involved, for example, in transcriptional regulation, proliferation and chromatin remodeling. In this study, we used exome sequencing data to analyze the mutation frequency of all the ARID domain containing genes in 25 microsatellite unstable (MSI) colorectal cancers (CRCs) as a first systematic effort to characterize the mutation pattern of the whole ARID gene family. Genes which fulfilled the selection criteria in this discovery set (mutations in at least 4/25 [16%] samples, including at least one nonsense or splice site mutation) were chosen for further analysis in an independent validation set of 21 MSI CRCs. We found that in addition to ARID1A, which was mutated in 39% of the tumors (18/46), also ARID1B (13%, 6/46), ARID2 (13%, 6/46) and ARID4A (20%, 9/46) were frequently mutated. In all these genes, the mutations were distributed along the entire length of the gene, thus distinguishing them from typical MSI target genes previously described. Our results indicate that in addition to ARID1A, other members of the ARID gene family may play a role in MSI CRC. PMID:24382590

Cajuso, Tatiana; Hänninen, Ulrika A; Kondelin, Johanna; Gylfe, Alexandra E; Tanskanen, Tomas; Katainen, Riku; Pitkänen, Esa; Ristolainen, Heikki; Kaasinen, Eevi; Taipale, Minna; Taipale, Jussi; Böhm, Jan; Renkonen-Sinisalo, Laura; Mecklin, Jukka-Pekka; Järvinen, Heikki; Tuupanen, Sari; Kilpivaara, Outi; Vahteristo, Pia

2014-08-01

237

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

238

Characterizing avulsion stratigraphy in ancient alluvial deposits  

NASA Astrophysics Data System (ADS)

Guidelines for identifying ancient avulsion deposits were set forth by Kraus and Wells [Kraus, M.J., Wells, T.M., 1999. Recognizing avulsion deposits in the ancient stratigraphical record. In: Smith, N.D., Rogers, J. (Eds.), Fluvial Sedimentology VI, Special Publication of the International Association of Sedimentologists, vol. 28, pp. 251-268], building on the study by Smith et al. [Smith, N.D., Cross, T.A., Dufficy, J.P., Clough, S.R., 1989. Anatomy of an avulsion. Sedimentology 36, 1-23] of the modern Saskatchewan River system (Cumberland Marshes, central Canada), and serve to characterize avulsion depositional sequences in the ancient Willwood and Fort Union Formations (Paleogene, Bighorn Basin, NW Wyoming, USA). We recognize, however, that the model is not universally applicable to avulsion-dominated successions, specifically systems which lack defining "heterolithic avulsion deposits", set forth by Kraus and Wells [Kraus, M.J., Wells, T.M., 1999. Recognizing avulsion deposits in the ancient stratigraphical record. In: Smith, N.D., Rogers, J. (Eds.), Fluvial Sedimentology VI, Special Publication of the International Association of Sedimentologists, vol. 28, pp. 251-268]. Observations in several fluvial intervals suggest that the avulsion stratigraphy outlined by Kraus and Wells [Kraus, M.J., Wells, T.M., 1999. Recognizing avulsion deposits in the ancient stratigraphical record. In: Smith, N.D., Rogers, J. (Eds.), Fluvial Sedimentology VI, Special Publication of the International Association of Sedimentologists, vol. 28, pp. 251-268] represents one category of avulsion stratigraphy found in the rock record, but does not capture the nature of avulsion deposits everywhere. Based on observations (using measured sections, outcrop photo-panels, and aerial photographs) in the Willwood Formation (Eocene, Wyoming) and Ferris Formation (Cretaceous/Paleogene, Wyoming), we present two end-member categories of avulsion stratigraphy in ancient deposits; stratigraphically abrupt, when a main paleochannel is stratigraphically juxtaposed directly atop floodplain/overbank deposits, and stratigraphically transitional, where crevasse splays and other non-floodplain/-overbank deposits stratigraphically precede a main paleochannel. This characterization provides a broader, more inclusive way to recognize and describe avulsion stratigraphy in ancient deposits and may be an important factor to consider when modeling connectivity in fluvial reservoirs. Furthermore, our observations show that one type of avulsion channel stratigraphy may prevail over another within an ancient basin, suggesting that system-wide factors such as splay-proneness or avulsion style (i.e. aggradational, incisional, etc.; [Slingerland, R., Smith, N.D., 2004. River avulsions and their deposits. Annual Review of Earth and Planetary Sciences 32, 257-285]) may be primary controls on the type of avulsion stratigraphy deposited and preserved in ancient basin-fills.

Jones, H. L.; Hajek, E. A.

2007-11-01

239

Chloride mass-balance method for estimating ground water recharge in arid areas: examples from western Saudi Arabia  

NASA Astrophysics Data System (ADS)

The chloride mass-balance method, which integrates time and aerial distribution of ground water recharge, was applied to small alluvial aquifers in the wadi systems of the Asir and Hijaz mountains in western Saudi Arabia. This application is an extension of the method shown to be suitable for estimating recharge in regional aquifers in semi-arid areas. Because the method integrates recharge in time and space it appears to be, with certain assumptions, particularly well suited for and areas with large temporal and spatial variation in recharge. In general, recharge was found to be between 3 to 4% of precipitation — a range consistent with recharge rates found in other and and semi-arid areas of the earth.

Bazuhair, Abdulghaffar S.; Wood, Warren W.

1996-11-01

240

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

241

A Sediment Transport Model for Straight Alluvial Channels  

Microsoft Academic Search

The paper presents a simple mathematical model for sediment transport in straight alluvial channels. The model, which is based on physical ideas related to those introduced by Bagnold (1954), was originally developed in two steps, the first describing the bed load transport (Engelund 1975) and the second account- ing for the suspended load (Fredsae and Engelund 1976). The model is

Frank Engelund; Jergen Fredsee

1976-01-01

242

Finite amplitude bars in mixed bedrock-alluvial channels  

NASA Astrophysics Data System (ADS)

We present a nonlinear asymptotic theory of fully developed flow and bed topography in a wide channel of constant curvature to describe finite amplitude perturbations of bottom topography, subject to an inerodible bedrock layer. The flow field is evaluated at the leading order of approximation as a slowly varying sequence of locally uniform flows, slightly perturbed by a weak curvature-induced secondary flow. Using the constraint of constant fluid discharge and sediment flux, we calculate an analytical solution for the cross-sectional profile of flow depth and bed topography, and we determine the average slope in the bend necessary to transport the sediment supplied from a straight, alluvial, upstream reach. Both fully alluvial bends and bends with partial bedrock exposure are shown to require a larger average slope than a straight upstream reach; the relative slope increase is much larger for mixed bedrock-alluvial bends. Curvature and sediment supply are shown to have a strong effect on the characteristics of the point bars in mixed bedrock-alluvial channels. Higher curvature bends produce bars of larger amplitude and more bedrock exposure through the cross section, and increasing the sediment supply leads to taller and wider point bars. Differences in the relative roughness of sediment and bedrock have a smaller, secondary effect on point bar characteristics. Our analytical approach can potentially be extended to the case of arbitrary, yet slowly varying, curvature, and should ultimately lead to an improved understanding of the formation of meanders in bedrock channels.

Nelson, Peter A.; Bolla Pittaluga, Michele; Seminara, Giovanni

2014-03-01

243

Alluvial charcoal in the Sigatoka Valley, Viti Levu Island, Fiji  

Microsoft Academic Search

Charcoal concentrations in alluvial sediments throughout the Sigatoka (and adjacent) catchments, western Viti Levu Island, Fiji were located, sampled and, where possible, dated. The earliest date (5579–5052 cal year BP) almost certainly predates human arrival and represents a natural fire, perhaps associated with drought conditions during an El Niño event. The next three dates are clustered around the time just

Patrick D. Nunn; Roselyn Kumar

2004-01-01

244

Effect of coal ash disposal upon an unconfined alluvial system  

Microsoft Academic Search

Fly and bottom ash from coal combustion has been disposed in four ash ponds in an alluvial valley. Three of the ash ponds are receiving ash and one was filled and closed. Twenty eight monitoring wells ranging in depth from 10 feet to 65 feet have been installed at the site to study groundwater flow and chemistry. Hydraulic heads are

B. S. Shergill; L. V. A. Sendlein; J. S. Dinger

1992-01-01

245

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

246

Seasonal Solute Cycling by Evapotranspiration and Flooding in a Semi-Arid Delta: The Okavango Delta, Botswana  

NASA Astrophysics Data System (ADS)

The Okavango River in semi-arid northwestern Botswana flows into an endorheic basin where its distributaries are developed on a large alluvial fan to form the dispersal system of the Okavango Delta. The river and its distributaries support a large pristine wetland complex which they inundate annually for 4 to 6 months. The semi-arid climate subjects the river and tributaries to high rates of evapotranspiration causing about 96% of the inflow into Botswana to be lost within the Delta. As an endorheic basin, it is one of the few river systems for which solutes are cycled entirely within the terrestrial system. We hypothesized that the seasonal flood pulse initiated by discharge from tropical Angola and the dense vegetation and hot climate cause variable response to influx, the temporal and spatial distribution and the recycling of solutes. Over a period of two years, we made hourly measurements of water levels, water temperature and electrical conductivity at four select locations distributed spatially across the Okavango Delta. We used SolonistTM level, temperature and conductivity loggers to record the readings. One of our objective was to document changes in water level that reflect flooding and non flooding conditions, water temperature which reflect seasonality and electrical conductivity which approximated the aqueous solute behavior. A second objective was to assess the timing and behavior of the aqueous solutes on a seasonal and short term (daily) basis in order to elucidate the effects of flooding and vegetation on the solute behavior. The flood pulse which enters the delta in February-March is highly attenuated by the redistribution in the distributaries and flooding of the wetlands. Discharge decreases from upstream to downstream due to this and the effects of evapotranspiration. The seasons are clearly observed in the water temperatures with higher water temperatures in the wet summer season and lower temperatures in the dry winter season. Overall, the aqueous solute concentration in the delta is generally higher in the wet summer season due to evapotranspiration and lower in the dry winter season due to dilution by flood waters. The solute concentration increase from upstream to downstream due to the longer residence time of water in the delta and greater exposure to evapotranspiration with distance downstream. During the winter when flooding occurs, the aqueous solute concentration increase initially during the rising limb of the flood pulse before decreasing as continued flooding of the delta continues. We suggest that the initial increase in the aqueous solute concentration is due to dissolution of solutes that accumulated in the floodplains and numerous islands from evapotranspiration in the summer and flushing of the solutes into the river and distributaries. The effect of vegetative evapo-concentration is observed on a diel basis with markedly higher solute concentrations during the day and lower concentrations at night. We conclude that evapotranspiration has a pronounced effect in controlling the aqueous solute concentration and its downriver concentration. In addition, previously precipitated solutes on land are cycled to river water by the initial phase of flooding.

Atekwana, E. A.; Molwalefhe, L.

2012-12-01

247

Do invasive riparian Tamarix alter hydrology of riparian areas of arid and semi-arid regions under climate change scenarios?  

NASA Astrophysics Data System (ADS)

Competitiveness of riparian invasive species, Tamarix, in arid and semi-arid riparian areas of the southwestern United States under climate change scenario (SRES A2) was investigated. Tamarix has been replacing native vegetation along the riparian corridors of these areas for the past several decades and is thought to alter water balance. Changes in depth to groundwater, soil moisture distribution and flood frequency are critical in survival and growth of a facultative phreatophyte such as Tamarix. In this study, a fully coupled 2d surface flow and 3d subsurface flow hydrologic model, HydroGeoSphere, was used to simulate surface-subsurface hydrology of the lower Virgin River basin (4500 sq. km), located in Nevada, Utah and Arizona. The hydrologic model results, depth to groundwater and soil saturation, were then applied to the species distribution model, Maxent, along with other bioclimatic parameters to asses future Tamarix distribution probability. Simulations were made for the climate scenarios of the end of 21st centry conditions. Depth to groundwater is found to be the most important predictor variable to the Maxent model. Future Tamarix distribution range is not uniform across the basin. It is likely to decrease at lower elevations and increase in some higher elevation areas.

Bhattarai, M. P.; Acharya, K.; Chen, L.

2012-12-01

248

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

249

Tectonic evolution of the Niksar and Tasova–Erbaa pull-apart basins, North Anatolian Fault Zone: their significance for the motion of the Anatolian block  

Microsoft Academic Search

The Tasova–Erbaa and Niksar basins are two adjacent pull-apart basins along the North Anatolian Fault Zone (NAFZ). Within the Tasova–Erbaa basin, sedimentary lithofacies of the Upper Pontus Formation (Plio-Pleistocene) are asymmetrically distributed, with laterally derived alluvial fans, coarse braid plain deposits, and axial braided stream deposits dominating the northern and western parts of the basin. The basin has gently dipping

Aykut Barka; H. Serdar Akyüz; Harvey A. Cohen; Fred Watchorn

2000-01-01

250

Modeling ground water flow in alluvial mountainous catchments on a watershed scale.  

PubMed

In large mountainous catchments, shallow unconfined alluvial aquifers play an important role in conveying subsurface runoff to the foreland. Their relatively small extent poses a serious problem for ground water flow models on the river basin scale. River basin scale models describing the entire water cycle are necessary in integrated water resources management and to study the impact of global climate change on ground water resources. Integrated regional-scale models must use a coarse, fixed discretization to keep computational demands low and to facilitate model coupling. This can lead to discrepancies between model discretization and the geometrical properties of natural systems. Here, an approach to overcome this discrepancy is discussed using the example of the German-Austrian Upper Danube catchment, where a coarse ground water flow model was developed using MODFLOW. The method developed uses a modified concept from a hydrological catchment drainage analysis in order to adapt the aquifer geometry such that it respects the numerical requirements of the chosen discretization, that is, the width and the thickness of cells as well as gradients and connectivity of the catchment. In order to show the efficiency of the developed method, it was tested and compared to a finely discretized ground water model of the Ammer subcatchment. The results of the analysis prove the applicability of the new approach and contribute to the idea of using physically based ground water models in large catchments. PMID:18459959

Wolf, Jens; Barthel, Roland; Braun, Jürgen

2008-01-01

251

The complementary relationship in estimation of regional evapotranspiration: The complementary relationship areal evapotranspiration and advection-aridity models  

NASA Astrophysics Data System (ADS)

Two implementations of the complementary relationship hypothesis for regional evapotranspiration, the Complementary Relationship Areal Evapotranspiration (CRAE) model and the Advection-Aridity (AA) model, are evaluated against independent estimates of regional evapotranspiration derived from long-term, large-scale water balances (1962-1988) for 120 minimally impacted basins in the conterminous United States. The CRAE model overestimates annual evapotranspiration by 2.5% of mean annual precipitation, and the AA model underestimates annual evapotranspiration by 10.6% of precipitation. Generally, increasing humidity leads to decreasing absolute errors for both models, and increasing aridity leads to increasing overestimation by the CRAE model and underestimation by the AA model, with the exception of high, arid basins, where the AA model overestimates evapotranspiration. Overall, the results indicate that the advective portion of the AA model must be recalibrated before it may be used successfully on a regional basis and that the CRAE model accurately predicts monthly regional evapotranspiration.

Hobbins, Michael T.; RamíRez, Jorge A.; Brown, Thomas C.; Claessens, Lodevicus H. J. M.

2001-05-01

252

Lake Murray, Fly and Strickland River Basins, Papua, New Guinea  

NASA Technical Reports Server (NTRS)

Lake Murray, a manmade reservoir, lies between the Fly and Strickland River Basins, Papua, New Guinea (7.0S, 141.5E). The region, photographed in sunglint, shows the water level in the reservoir and the full extent of the drainage basins of both river systems as the rivers meander through wide alluvial floodplains. Some forest clearing can be seen in places throughout the region, but most of the area remains in closed canopy forest.

1991-01-01

253

Reconstruction of the sediment transport conditions in the Quaternary Ürümqi alluvial system (northeast Tian Shan, China)  

NASA Astrophysics Data System (ADS)

Over the last twenty years, sediment transport by rivers and erosion dynamics have been the focus of a huge research effort. However, the morphological makers of erosion are often scarce, fragmented and they correspond to a very discontinuous record. At the outlet of drainage basins submitted to erosion, sedimentary series often constitute more frequent, perennial and continuous archives in space and through time for the evolution of reliefs upstream. Thus, some studies have used volumes of these deposits to roughly reconstruct this evolution. Yet, beyond their volume, the alluvial sediments also contain information about physical parameters of palaeorivers that have deposited them. That is why we decided to couple a physical analysis of water flow, erosion and transport in an active river with a faciological analysis of its present and past deposits to reconstruct some of its palaeohydraulic characteristics. As an example, we chose the northeastern foothills of the Tian Shan range where the Ürümqi braided and gravel-bed river is inset in its own Quaternary deposits. Hence, in this area, it is possible to observe and compare the present and ancient sediments of a single alluvial system. First, we gathered an extensive dataset on hydraulics and transport dynamics of the present river, as well as on grain size and structure of its deposits. These depositional features were characterized at the river-bed surface, but also in depth by the means of a trench. From the measurements performed, we built a facies model fully quantified, in term of grain and structure sizes of the present sediments, and calibrated regarding the relationships between deposition, transport and water flow. Additionally, we documented also the grain size and structure of the ancient Ürümqi deposits by describing the sediments of the Quaternary alluvial fan and terraces of the river. Eventually, the facies model calibrated in term of transport law and the data collected for the old deposits would be associated to reconstruct evolution curves of variables such as flow velocity or bed load during the study period (from - 250 to 0 kyr approximately). In this way, we hope to set the basis of palaeohydraulic reconstructions of the ancient Ürümqi river, which will bring precious information about the long-term sediment transport and erosion dynamics in the study area.

Guérit, Laure; Barrier, Laurie; Métivier, François; Narteau, Clément; Lajeunesse, Éric; Liu, Youcun; Ye, Beicheng

2010-05-01

254

Experimental alluvial fan evolution: Channel dynamics, slope controls, and shoreline growth  

NASA Astrophysics Data System (ADS)

River deltas and alluvial fans have channelization and deposition dynamics that are not entirely understood, but which dictate the evolution of landscapes of great social, economic, and ecologic value. Our lack of a process-based understanding of fan dynamics hampers our ability to construct accurate prediction and hazard models, leaving these regions vulnerable. Here we describe the growth of a series of experimental alluvial fans composed of a noncohesive grain mixture bimodal in size and density. We impose conditions that simulate a gravel/sand fan prograding into a static basin with constant water and sediment influx, and the resulting fans display realistic channelization and avulsion dynamics. We find that we can describe the dynamics of our fans in terms of a few processes: (1) an avulsion sequence with a timescale dictated by mass conservation between incoming flux and deposit volume; (2) a tendency for flow to reoccupy former channel paths; and (3) bistable slopes corresponding to separate entrainment and deposition conditions for grains. Several important observations related to these processes are: an avulsion timescale that increases with time and decreases with sediment feed rate; fan lobes that grow in a self-similar, quasi-radial pattern; and channel geometry that is adjusted to the threshold entrainment stress. We propose that the formation of well-defined channels in noncohesive fans is a transient phenomenon resulting from incision following avulsion, and can be directly described with dual transport thresholds. We present a fairly complete, process-based description of the mechanics of avulsion and its resulting timescale on our fans. Because the relevant dynamics depend only on threshold transport conditions and conservation of mass, we show how results may be directly applied to field-scale systems.

Reitz, Meredith D.; Jerolmack, Douglas J.

2012-06-01

255

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...

256

The timing of alluvial activity in Gale crater, Mars  

NASA Astrophysics Data System (ADS)

Curiosity rover's discovery of rocks preserving evidence of past habitable conditions in Gale crater highlights the importance of constraining the timing of responsible depositional settings to understand the astrobiological implications for Mars. Crater statistics and mapping reveal the bulk of the alluvial deposits in Gale, including those interrogated by Curiosity, were likely emplaced during the Hesperian, thereby implying that habitable conditions persisted after the Noachian. Crater counting data sets and upper Peace Vallis fan morphology also suggest a possible younger period of fluvial activation that deposited ~10-20 m of sediments on the upper fan after emplacement of the main body of the fan. If validated, water associated with later alluvial activity may have contributed to secondary diagenetic features in Yellowknife Bay.

Grant, John A.; Wilson, Sharon A.; Mangold, Nicolas; Calef, Fred; Grotzinger, John P.

2014-02-01

257

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

258

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

259

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

260

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

261

A review of the stratigraphy and sedimentary environments of the Karoo-aged basins of Southern Africa  

NASA Astrophysics Data System (ADS)

The Karoo Basin of South Africa was one of several contemporaneous intracratonic basins in southwestern Gondwana that became active in the Permo-Carboniferous (280 Ma) and continued to accumulate sediments until the earliest Jurassic, 100 million years later. At their maximum areal extent, during the early Permian, these basins covered some 4.5 million km 2. The present outcrop area of Karoo rocks in southern Africa is about 300 000 km 2 with a maximum thickness of some 8000 m. The economic importance of these sediments lies in the vast reserves of coal within the Ecca Group rocks of northern and eastern Transvaal and Natal, South Africa. Large reserves of sandstone-hosted uranium and molybdenum have been proven within the Beaufort Group rocks of the southern Karoo trough, although they are not mineable in the present market conditions. Palaeoenvironmental analysis of the major stratigraphic units of the Karoo succession in South Africa demonstrates the changes in depositional style caused by regional and localized tectonism within the basin. These depocentres were influenced by a progressive aridification of climate which was primarily caused by the northward drift of southwestern Gondwana out of a polar climate and accentuated by the meteoric drying effect of the surrounding land masses. Changing palaeoenvironments clearly influenced the rate and direction of vertebrate evolution in southern Gondwana as evidenced by the numerous reptile fossils, including dinosaurs, which are found in the Karoo strata of South Africa, Lesotho, Namibia and Zimbabwe. During the Late Carboniferous the southern part of Gondwana migrated over the South Pole resulting in a major ice sheet over the early Karoo basin and surrounding highlands. Glacial sedimentation in upland valleys and on the lowland shelf resulted in the Dwyka Formation at the base of the Karoo Sequence. After glaciation, an extensive shallow sea covered the gently subsiding shelf, fed by large volumes of meltwater. Marine clays and muds accumulated under cool climatic conditions (Lower Ecca Group) including the distinctive Mesosaurus-bearing carbonaceous shales of the Whitehill Formation. Subduction of the palaeo-Pacific plate reslted in an extensive chain of mountains which deformed and later truncated the southern rim of the main Karoo Basin. Material derived from these "Gondwanide" mountains as well as from the granitic uplands to the north-east, accumulated in large deltas that prograded into the Ecca sea (Upper Ecca Group). The relatively cool and humid climate promoted thick accumulations of peat on the fluvial and delta plains which now constitute the major coal reserves of southern Africa. As the prograding deltas coalesced, fluvio-lacustrine sediments of the Beaufort Group were laid down on broad gently subsiding alluvial plains. The climate by this time (Late Permian) had warmed to become semi-arid with highly seasonal rainfall. Vegetation alongside the meander belts and semi-permanent lakes supported a diverse reptilian fauna dominated by therapsids or "mammal-like reptiles". Pulses of uplift in the southern source areas combined with possible orographic effects resulted in the progadation of two coarse-grained alluvial fans into the central parts of the basin (Katberg Sandstone Member and Molteno Formation). In the upper Karoo Sequence, progressive aridification and tectonic deformation of the basin through the late Triassic and early Jurassic led to the accumulation, in four separate depositories, of "redbeds" which are interpreted as fluvial and flood-fan, playa and dune complexes (Elliot Formation). This eventually gave way to westerly wind-dominated sedimentation that choked the remaining depositories with fine-grained dune sand. The interdune areas were damp and occasionally flooded and provided a habitat for small dinosaurs and the earliest mammals. During this time (Early Jurassic), basinwide volcanic activity began as a precursor to the break-up of Gondwana in the late Jurassic and continued until the early Cretaceous. This

Smith, R. M. H.; Eriksson, P. G.; Botha, W. J.

1993-02-01

262

Valuing Water: variability and the Lake Eyre Basin, central Australia  

Microsoft Academic Search

‘Environmental values’ form an increasingly important component of natural resource management, but use of the term ‘value’ is dominated by a narrow and limiting utility-based definition. In this paper I consider theories of value and practices of valuing water in the arid and semi-arid Lake Eyre Basin, central Australia. While value is the subject of diverse meanings—both within a range

Leah M. Gibbs

2006-01-01

263

Estimates of Ground-Water Recharge in Wadis of Arid, Mountainous Areas Using the Chloride Mass-Balance Approach  

NASA Astrophysics Data System (ADS)

Evaluation of ground-water supply in arid areas requires estimation of annual recharge. Traditional physical-based hydrologic estimates of ground-water recharge result in large uncertainties when applied in arid, mountainous environments because of infrequent, intense rainfall events, destruction of water-measuring structures associated with those events, and consequent short periods of hydrologic records. To avoid these problems and reduce the uncertainty of recharge estimates, a chloride mass-balance (CMB) approach was used to provide a time-integrated estimate. Seven basins exhibiting dry-stream beds (wadis) in the Asir and Hijaz Mountains, western Saudi Arabia, were selected to evaluate the method. Precipitation among the basins ranged from less than 70 mm/y to nearly 320 mm/y. Rain collected from 35 locations in these basins averaged 2.0 mg/L chloride. Ground water from 140 locations in the wadi alluvium averaged 200 mg/L chloride. This chloride concentration ratio of precipitation to ground water suggests that on average, approximately 1 percent of the rainfall is recharged, while the remainder is lost to evaporation. Ground-water recharge from precipitation in individual basins ranged from less than 1 to nearly 4 percent and was directly proportional to total precipitation. Independent calculations of recharge using Darcy's Law were consistent with these findings and are within the range typically found in other arid areas of the world. Development of ground water has lowered the water level beneath the wadis and provided more storage thus minimizing chloride loss from the basin by river discharge. Any loss of chloride from the basin results in an overestimate of the recharge flux by the chloride-mass balance approach. In well-constrained systems recharge in arid, mountainous areas where the mass of chloride entering and leaving the basin is known or can be reasonably estimated, the CMB approach provides a rapid, inexpensive method for estimating time-integrated ground-water recharge.

Wood, W. W.; Wood, W. W.

2001-05-01

264

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

265

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

266

Hydrology of the Bayou Bartholomew alluvial aquifer-stream system, Arkansas  

USGS Publications Warehouse

The study area comprises about 3,200 square miles of the Mississippi Alluvial Plain in southeast Arkansas. About 90 percent of the area drains south to the Ouachita River in Louisiana. The alluvial aquifer and the streams are hydraulically connected and are studied as an aquifer-stream system. Bayou Bartholomew is a principal stream of the system. The aquifer is underlain by confining strata of the Jackson Group and Cockfield Formation. The mean annual surface-water yield of the area that drains to the Ouachita River basin is nearly 2 million acre-feet. Flood-control projects have significantly reduced flooding in the area. Basin boundaries and low-flow characteristics of streams have been altered as a result of the flood-control projects and streamflow diversion for irrigation. The direction of ground-water flow generally is southward. Bayou Bartholomew functions mostly as a drain for ground-water flow from the west and as a recharge source to the aquifer east of the bayou. As a result of navigation pools, the Arkansas River is mostly a steady-recharge source to the aquifer. Pumpage from the aquifer and streams increased from about 20,000 acre-feet in 1941 to 237,000 acre-feet in 1970. Estimates of flow, derived from analog analysis but lacking field verification, indicate that recharge to the aquifer in 1970 was about 161,000 acre-feet. About 70 percent of the recharge was by capture from streams as a result of ground-water pumpage. Discharge from the aquifer was about 233,000 acre-feet. About 80 percent of the discharge was through wells. Stream diversion in 1970 from capture and open channel, excluding capture from the Arkansas and Mississippi Rivers, was about 110,000 acre-feet. Return flow to streams from rice irrigation and fishponds was about 60,000 acre-feet. The chemical quality of streamflows is excellent for irrigation. Water from the aquifer generally ranges from permissible to excellent for irrigation. The use of water from the aquifer in the flood-plain area, exclusive of irrigation, is severely limited unless it is treated to remove the iron and reduce the hardness.

Broom, M. E.; Reed, J. E.

1973-01-01

267

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

268

Hydrologic and geologic factors controlling surface and groundwater chemistry in Indian Wells-Owens Valley area, southeastern California, USA  

Microsoft Academic Search

The Indian Wells-Owens Valley area is located in the semi-arid Basin and Range province, which is characterized by alternating mountains and alluvial basins. Surface water resources are limited in this arid region and water demand is mainly met by groundwater pumpage. In a classic Basin and Range groundwater system, water flows from recharge areas in the mountains to discharge areas

Cüneyt Güler; Geoffrey D. Thyne

2004-01-01

269

Stratigraphy of Pennsylvanian detrital reservoirs, Permian basin  

SciTech Connect

Significant oil reserves have been found to date in stratigraphic traps in Pennsylvanian detrital reservoirs on the Central Basin platform and Reagan uplift of the Permian basin. The 32 MMBOEG Arenoso field area, discovered in 1966, is the largest producing field. Along a 75 mi northwest-southeast trend, 23 other smaller fields will produce an average 850 MBOEG each, for a total estimated ultimate recovery to date in the trend of 52 MMBOEG. These stratigraphic traps are elusive and complex. However, reservoir quality is excellent, and because of the poorly understood trap types, significant reserves remain to be found in the trend. The Pennsylvanian detrital consists of chert cobble conglomerates, coarse sands, red shales, and gray limestones deposited in an environment that grades seaward from alluvial fan to braided stream to shallow marine. The chert cobble conglomerates of the alluvial fan facies and the coarse sands of the braided stream facies are the highest quality pay zones. Porosities range from 5 to 20%, with permeability ranging up to 26 d. The total unit is seldom more than 400 ft thick; reservoir rock thicknesses within the unit range up to 100 ft. Because of the complex nature of the alluvial fan and braided stream deposits, dry development wells can be expected within fields. These Strawn deposits are located adjacent to and overlying the eroded lower Paleozoic uplifts of the southern Central Basin platform. The major source of the chert cobbles is erosion of the Devonian tripolitic chert. Renewed structural uplift combined with sea level drop in the middle Wolfcampian locally truncated some Pennsylvanian detrital alluvial fan deposits, and complicated or destroyed a potential trap by depositing Wolfcamp chert conglomerates on top of the Pennsylvanian conglomerates.

Van Der Loop, M. (Arco Oil and Gas Co., Midland, TX (United States))

1992-04-01

270

Probable flood predictions in ungauged coastal basins of El Salvador  

USGS Publications Warehouse

A regionalization procedure is presented and used to predict probable flooding in four ungauged coastal river basins of El Salvador: Paz, Jiboa, Grande de San Miguel, and Goascoran. The flood-prediction problem is sequentially solved for two regions: upstream mountains and downstream alluvial plains. In the upstream mountains, a set of rainfall-runoff parameter values and recurrent peak-flow discharge hydrographs are simultaneously estimated for 20 tributary-basin models. Application of dissimilarity equations among tributary basins (soft prior information) permitted development of a parsimonious parameter structure subject to information content in the recurrent peak-flow discharge values derived using regression equations based on measurements recorded outside the ungauged study basins. The estimated joint set of parameter values formed the basis from which probable minimum and maximum peak-flow discharge limits were then estimated revealing that prediction uncertainty increases with basin size. In the downstream alluvial plain, model application of the estimated minimum and maximum peak-flow hydrographs facilitated simulation of probable 100-year flood-flow depths in confined canyons and across unconfined coastal alluvial plains. The regionalization procedure provides a tool for hydrologic risk assessment and flood protection planning that is not restricted to the case presented herein. ?? 2008 ASCE.

Friedel, M. J.; Smith, M. E.; Chica, A. M. E.; Litke, D.

2008-01-01

271

Remote sensing classification of the arid watersheds of Iran  

NASA Astrophysics Data System (ADS)

Iran's most obvious hydroclimatic problems are compounded of the disadvantages of scanty and highly seasonal precipitation and a surface configuration which tends to concentrate moisture on the periphery of the country, leaving its vast heart an area of irreconcilable sterility. Most of the central Iran has arid conditions with dry and hot summer months, when streams with and the land is parched. Nowhere in Iran is there an annual surplus of water, and significant seasonal surpluses occur in only the wishbone of high mountains that encloses the central plateau on the north and west. In most parts (about 80 percent of the total of country) the nature of human activity depends upon the availability of surface water that can be tapped by wells and qantas. Runoff is episodic and occurs only because the precipitation, meagre as it is momentarily exceeds the infiltration capability of the surface. Such precipitation is not of course capricious in terms of quantity, location and distribution in time. For more accurate investigation, remote sensing data was used to overcome the large area. Finally for arid basins, combined data from remote sensing (Cosmos and Aerial photographs) data and topography maps provided significant results.

Solaimani, Karim; Habibnejad-Roshan, Mahmud

2002-01-01

272

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

273

InSAR Reveals Aquifer System Response in Heavily Pumped Basins in Nevada: A Tool for Groundwater Resource Management  

Microsoft Academic Search

Owing to the arid climate and a rapidly growing population, many pumped groundwater basins in Nevada are experiencing declining water levels. We have been conducting InSAR studies in selected groundwater basins of Nevada in order to better understand the physical character and response of these heavily pumped aquifer systems. Our results for three basins in southern Nevada illustrate how InSAR

J. W. Bell; F. Amelung; M. Bianchi; A. Ferretti; F. Novali; G. W. Bawden

2005-01-01

274

Estimating Terrestrial Water Storage Changes in the Colorado River Basin: Atmospheric Data Analysis, Satellite Remote Sensing and Hydrologic Modeling  

Microsoft Academic Search

The Colorado River basin covers about 637 000 km2 and spreads over the southwestern United States and a small portion of Mexico. Much of the basin is arid, and runoff derives from the high elevation snow pack over the Rocky Mountains, which contributes about 70% of the annual runoff. A secondary source of water for the basin is the summer

P. A. Troch; S. Seneviratne; M. Hirschi; R. Hurkmans; S. Hasan; M. Durcik

2006-01-01

275

Water and the arid lands of the western United States  

SciTech Connect

The United States is water-rich, but conflicts over water development and use are increasing. Today, economic scarcity - not absolute physical scarcity - is the key issue in many places. In the arid American West, traditionally over 90 percent of the water consumed has been used to irrigate agriculture. But as cities grow and the states's economies diversify, municipal, commercial, and industrial uses exert more pressure. At the same time, groundwater mining and water quality degradation are becoming commonplace. The challenge is to increase productivity while equitably distributing the costs and benefits of water use. This book includes three case studies that cover primarily agricultural areas (the Central Valley of California, the High Plains of Texas, and the upper Colorado River basin) and three on the problems of metropolitan areas (Denver, Tucson, and the southern California megalopolis). The authors also identify policies that could help the West sustain economic growth without destroying or undervaluing its natural resources.

El-Ashry, M.T.; Gibbons, D.C.

1988-01-01

276

Tectonics of west central New Mexico and adjacent Arizona: a remote sensing and field study in arid and semi-arid areas  

SciTech Connect

Large-scale fault zones in west-central New Mexico and eastern Arizona were mapped using conventional fieldwork aided by Landsat and Seasat images and high altitude air photos. These faults, which are of post-early Miocene age, trend NE-SW and N-S and extend over 200 km. The fault zones bound very large horst and graben blocks which, although located on the physiographic Colorado Plateau, are characteristic of Basin and Range deformation. Their intersection has been the locus of extensive Cenozoic volcanism. The procedure developed in this project permitted investigation of an area of about 1.8 x 10/sup 5/ km/sup 2/ of arid and semi-arid land whose structures previously were poorly defined.

Baldridge, W.S.; Bartov, Y.; Kron, A.

1981-01-01

277

Using major ions and ?15N-NO3(-) to identify nitrate sources and fate in an alluvial aquifer of the Baiyangdian lake watershed, North China Plain.  

PubMed

In semi-arid regions, most human activities occur in alluvial fan areas; however, NO3(-) pollution has greatly threatened the shallow groundwater quality. In this paper, ?(15)N-NO3(-) and multi-tracers were used to identify the origin and fate of NO3(-) in groundwater of the Baiyangdian lake watershed, North China Plain. The investigation was conducted in two typical regions: one is the agricultural area located in the upstream of the watershed and another is the region influenced by urban wastewater in the downstream of the watershed. Results indicate that the high NO3(-) concentrations of the upstream shallow groundwater were sourced from fertilizer and manure or sewage leakage, whilst the mixture and denitrification caused the decrease in the NO3(-) concentration along the flow path of the groundwater. In the downstream, industrial and domestic effluent has a great impact on groundwater quality. The contaminated rivers contributed from 45% to 76% of the total recharge to the groundwater within a distance of 40 m from the river. The mixture fraction of the wastewater declined with the increasing distance away from the river. However, groundwater with NO3(-) concentrations larger than 20 mg l(-1) was only distributed in areas near to the polluted river or the sewage irrigation area. It is revealed that the frontier and depression regions of an alluvial fan in a lake watershed with abundant organics, silt and clay sediments have suitable conditions for denitrification in the downstream. PMID:23743546

Wang, Shiqin; Tang, Changyuan; Song, Xianfang; Yuan, Ruiqiang; Wang, Qinxue; Zhang, Yinghua

2013-07-01

278

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.

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

2000-01-01

279

Dynamics of Floodwater Infiltration and Groundwater Recharge Under Ephemeral Channels in Arid Regions  

NASA Astrophysics Data System (ADS)

Shallow alluvial aquifers underneath ephemeral streams are often the only reliable source of water that can sustain human habitation in arid environments (e.g. Arava Valley, Israel; Rio Andarax, Spain; Kuiseb River, Namibia). The main source of replenishment of these alluvial aquifers is recharge from floodwater infiltration. Accordingly, effective management of surface water and groundwater in arid regions requires a better understanding of the processes controlling floodwater infiltration and recharge of alluvial aquifers. This study focuses on understanding the dynamic process of floodwater infiltration from ephemeral channels while implementing innovative methods specifically designed to quantify the recharge fluxes. The monitoring system provides real-time continuous measurements of the hydraulic conditions in all three domains involved in the recharge process: (a) the flood, (b) water-content variations along the unsaturated profile, (c) the groundwater response to the recharge event. Water-content variations along the unsaturated profile were monitored using flexible TDR (FTDR) probes installed along slanted boreholes underneath the stream channel. Water levels and salinity of both the flood and the groundwater were measured simultaneously. Two study sites were selected for this work: the Buffels River, South Africa and the Kuiseb River, Namibia. The monitoring stations installed at those sites recorded several flood events during 2005/2006. Data collected during this period revealed the dynamic process in which floodwater percolates through the vadose zone and recharges the groundwater. Each flood initiated an infiltration event expressed by wetting of the vadose zone and a rise in the water table. The sequential wetting of the vadose zone allowed direct calculations of the wetting-front propagation velocities and percolation fluxes from land surface down to the groundwater. With the arrival of the wetting front to the water table, groundwater began to rise, indicating an increase in groundwater storage in response to the recharge event. Water fluxes were calculated using several independent methods: (a) combining the calculated wetting-front propagation velocity with the change in moisture profile, (b) the rate at which the water table rises as an indication of the percolation rate, and (c) the final increase in groundwater storage through the measured change in groundwater levels. Interestingly, the calculations performed for all of the floods yielded corresponding flux values of approximately 1 cm/h. Aquifer dimensions, as well as total recharge estimations, were also derived from the data. Salt-transport dynamics at each site and the positive influence of the flood events on groundwater quality were revealed from the EC measurements.

Tatarsky, B.; Dahan, O.; Enzel, Y.

2007-05-01

280

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

281

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

282

THE STATE OF UNDERSTANDING ON GROUNDWATER RECHARGE FOR THE SUSTAINABLE MANAGEMENT OF TRANSBOUNDARY AQUIFER IN THE LAKE CHAD BASIN  

Microsoft Academic Search

Water resource management in the arid to semi-arid areas requires not only exploration and assessment of the available reserves, but also determination of groundwater recharge in order to evaluate the sustainable yield of the ressource. This paper highlights some key groundwater recharge studies on the Chad basin Quaternary aquifer using diverse methodologies : piezometric map, water balance, water table fluctuation

B. Ngounou Ngatcha; J. Mudry; C. Leduc

283

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

284

Combined velocity and depth mapping on developing laboratory alluvial fans  

NASA Astrophysics Data System (ADS)

Large-scale particle image velocimetry (LSPIV) is a nonintrusive method for measuring free-surface velocities using tracer patterns in a sequence of images. This method has been applied in both natural rivers and large-scale hydraulic models (Muste et al., 2008). Here the method is used to map channel and sheet flow velocity during the development of laboratory-scale alluvial fans. Measuring the time and space varying hydraulics on laboratory fans by traditional methods is not practical since flows are quite shallow (~1 cm). Additionally, the highly dynamic environment makes positioning of traditional probe-type instruments difficult and their physical presence could alter autogenic fan evolution. These difficulties can be overcome by using particle image velocimetry techniques. Furthermore, images collected in the LSPIV method can be used to extract flow depth using a calibrated dye-intensity method (Gran and Paola, 2001). This allows for simultaneous measurement of flow velocity and depth everywhere over the fan at any point in time. To validate the method, a set of controlled small-scale experiments were run for depths ranging from 0.2-1.5 cm and velocities from 10-100 cm/sec. Comparison of the LSPIV and dye-intensity method measurements to the known values indicated that the methodology was able to accurately capture simultaneous flow velocity and depth in this range of conditions, i.e., those encountered during the development of laboratory-scale alluvial fans and streams. The method is then used to map the hydraulics associated with various fan processes during development as demonstrated in figure 1. The ability to measure hydraulic properties during fan development is important since physical models provide an arena for observing the time evolution and morphodynamic feedback in depositional systems such as alluvial fans.

Hamilton, P.; Strom, K. B.; Hoyal, D. C.

2011-12-01

285

Sediment Transfer-Storage Relations for Degrading Alluvial Reservoirs  

NASA Astrophysics Data System (ADS)

The routing of sediment through a drainage system is mediated by transfer-storage relations that are particular to each alluvial reservoir, which contains a channel and floodplain. We propose that sediment transfer rate for a given annual distribution of streamflow is a positive function of sediment storage and examine these relations for degrading reservoirs in which sediment is evacuated by incision and corrasion. Previous laboratory experiments of sediment-starved channels that model gravel-bed rivers show rapid, linear degradation in initially unarmored beds during non-selective transport, followed by decreasing rates of incision with the onset of selective transport, armoring, and bed structuring. Together, these phases of incision produce nonlinear decreases in sediment output with decreasing bed elevation. A comparison of experimental results and numerical simulations of armoring indicates that the depth of incision achieved at a final low reference transport rate depends on initial transport stage and particle sorting. Typical values of Shields stress for gravel-bed rivers force deep incision in well-sorted material (sigmaG<1) and shallow incision (a few surface layers or less) in poorly sorted material (sigmaG>1.5). This contrast suggests that changes in storage in response to variations in sediment supply are small in river reaches with poor sorting and large in those with superior sorting. Nakamura and Kikuchi [1996] find that, in the absence of large floods, the annual rate of erosion of floodplain surfaces decreases exponentially with age. We use their model for corrasion in the Saru River, Japan, and arbitrary functions for rates of incision suggested by our previous analysis to simulate degradation over a 40-year period, starting with an initially filled alluvial reservoir. Storage volume decreases more rapidly than exponential regardless of whether or not incision is modeled as exponential with time. This suggests that a general form of sediment transfer-storage relations for degrading alluvial reservoirs is positive and nonlinear.

Lisle, T. E.; Church, M.

2001-12-01

286

Unsaturated Flow in an Arid Environment.  

National Technical Information Service (NTIS)

Unsaturated flow of water in an arid environment requires a more exacting application of theory/experiment than needed in irrigated agriculture, which heretofore has been the principal motivation for developing unsaturated flow understanding in the U.S. S...

C. M. Case

1981-01-01

287

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

288

Elevated Mercury Concentrations in Alluvial Deposits of the Humid Tropics of South America: Natural vs. Anthropogenic Sources  

NASA Astrophysics Data System (ADS)

Mercury (Hg) amalgamation is extensively used throughout the humid tropics of South America for the extraction of fine-gold particles from secondary ore deposits. Early studies of water, sediments and fish generally concluded that these gold mining operations have extensively contaminated the aquatic environment. However, investigations along a 900-km reach of the Maderia River, Brazil suggest that while Hg values in sediments and water are above global averages, the high mercury levels are largely due to natural sources. Of primary significance is the inability to distinguish between Hg concentrations in upland soils (oxisols) and modern channel and floodplain deposits. Spatial trends in the data suggest that the impact of anthropogenically released Hg from mine sites is relatively localized. This conclusion is supported by other, independent studies in the Rio Negro basin where elevated Hg values were found in terrace deposits in spite of the fact that no modern mining activities are known to occur within the watershed. Moreover, Roulet and his colleagues have demonstrated using mass balance calculations that within the Tapajos River basin as much as 97 percent of Hg in the alluvial deposits is derived from Hg enriched oxisols eroded during deforestation. In a regional examination of Hg levels within alluvial deposits of Essequibo and Mazaruni Rivers of Guyana, we again found that Hg levels were above both regional background values (10 to 80 ppb) and global averages. However, deforestation within these watersheds is limited, reducing the influx of Hg from eroded upland soils. In addition, the spatial trends in Hg concentrations suggest a closer link between mining activities and Hg values than is found in Maderia River of Brazil. It is unclear at this time, however, whether the primary Hg source in Guyana is the direct input of Hg to the river during amalgamation, or to the influx of Hg enriched soils eroded during the dredging of channel bed sediments and hydraulic mining of floodplain materials.

Miller, J. R.; Lechler, P. J.

2001-12-01

289

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

290

Photodegradation Pathways in Arid Ecosystems  

NASA Astrophysics Data System (ADS)

Recent interest in improving our understanding of decomposition patterns in arid and semi-arid ecosystems and under potentially drier future conditions has led to a flurry of research related to abiotic degradation processes. Oxidation of organic matter by solar radiation (photodegradation) is one abiotic degradation process that contributes significantly to litter decomposition rates. Our meta-analysis results show that increasing solar radiation exposure corresponds to an average increase of 23% in litter mass loss rate with large variation among studies associated primarily with environmental and litter chemistry characteristics. Laboratory studies demonstrate that photodegradation results in CO2 emissions. Indirect estimates suggest that photodegradation could account for as much as 60% of ecosystem CO2 emissions from dry ecosystems, but these CO2 fluxes have not been measured in intact ecosystems. The current data suggest that photodegradation is important, not only for understanding decomposition patterns, but also for modeling organic matter turnover and ecosystem C cycling. However, the mechanisms by which photodegradation operates, along with their environmental and litter chemistry controls, are still poorly understood. Photodegradation can directly influence decomposition rates and ecosystem CO2 flux via photochemical mineralization. It can also indirectly influence biotic decomposition rates by facilitating microbial degradation through breakdown of more recalcitrant compounds into simpler substrates or by suppressing microbial activity directly. All of these pathways influence the decomposition process, but the relative importance of each is uncertain. Furthermore, a specific suite of controls regulates each of these pathways (e.g., environmental conditions such as temperature and relative humidity; physical environment such as canopy architecture and contact with soil; and litter chemistry characteristics such as lignin and cellulose content), and these controls have not yet been identified or quantified. To advance our understanding of photodegradation and its role in decomposition and in ecosystem C cycling, we must characterize its mechanisms and their associated controls and incorporate this understanding into biogeochemical models. Our objective is to summarize the current state of understanding of photodegradation and discuss some paths forward to address remaining critical gaps in knowledge about its mechanisms and influence on ecosystem C balance.

King, J. Y.; Lin, Y.; Adair, E. C.; Brandt, L.; Carbone, M. S.

2013-12-01

291

The migration, dissolution, and fate of chlorinated solvents in the urbanized alluvial valleys of the southwestern USA  

NASA Astrophysics Data System (ADS)

The migration, dissolution, and subsequent fate of spilled chlorinated solvents in the urban alluvial valleys of the southwestern U.S. appear to be governed by a unique set of hydrogeologic and geochemical processes occurring within terrigeneous clastic depositional systems. The alluvial and lacustrine fill of the basins, the trapping of solvents in fine-grained sediments beneath the urbanized valley centers, the oxic conditions typical of the deeper alluvium, and the contaminant-transport patterns produced by large-scale basin pumping combine to produce long aqueous-phase plumes derived from the dissolution of trapped chlorinated solvents. Although of limited aqueous solubility, these dense solvents are sufficiently mobile and soluble in the southwestern alluvial valleys to have produced aqueous plumes that have migrated several kilometers through the deeper alluvium and have contaminated valuable water-supply well fields in California, Arizona, and New Mexico. The typical length of these plumes and the presence of oxic groundwater indicate that it is unlikely that natural attenuation will be a practical remedial option in the southwestern alluvial valleys or in other alluvial systems in which similar hydrogeologic and geochemical conditions exist. Résumé La migration, la dissolution et l'évolution consécutive des rejets de solvants chlorés dans les vallées alluviales du sud-ouest des États-Unis paraissent déterminées par un même ensemble de processus hydrogéologiques et géochimiques intervenant dans des formations de dépôts clastiques terrigènes. Les remplissages alluviaux et lacustres des bassins, le piégeage des solvants par des sédiments fins sous les centres des vallées urbanisées, les conditions oxiques typiques des alluvions plus profondes et les types de transport de contaminants provoqués par le pompage à l'échelle du bassin se combinent pour produire des panaches, étendus dans la phase aqueuse, provenant de la dissolution de solvants chlorés piégés. Malgré leur faible solubilité dans l'eau, ces solvants denses sont suffisamment mobiles et solubles pour avoir produit, dans le sud-ouest des vallées alluviales, des panaches aqueux qui ont migré de plusieurs kilomètres dans les alluvions plus profondes et ont contaminé des champs captants pour l'eau potable en Californie, en Arizona et au Nouveau-Mexique. La longueur de ces panaches et la présence d'eau souterraine en conditions oxiques indiquent qu'il est peu probable que la décroissance naturelle soit un recours pratique de décontamination dans les vallées alluviales du sud-ouest ou dans d'autres systèmes alluviaux dans lesquels existent des conditions hydrogéologiques et géochimiques semblables. Resumen La migración, disolución y transporte de compuestos clorados en valles aluviales urbanos del sudoeste de los Estados Unidos de América parecen estar gobernados por un conjunto único de procesos hidrogeológicos y geoquímicos que tienen lugar en los depósitos clásticos. El relleno aluvial y lacustre de las cuencas, la inmovilización de los solutos en sedimentos de grano fino bajo las zonas urbanizadas, los condiciones óxicas típicas del aluvial profundo y las direcciones de transporte regidas por los fuertes bombeos en las cuencas se combinan para producir grandes penachos en fase acuosa procedentes de la disolución de los compuestos clorados atrapados en el medio. Aunque la solubilidad de estos compuestos clorados densos es pequeña, es suficiente para producir penachos que en algunos casos se han desplazado varios kilómetros a través del aluvial profundo y han llegado a contaminar zonas de extracción muy productivas en California, Arizona y Nuevo México. La longitud de estos penachos y la presencia de agua subterránea oxidante indican que es improbable que la degradación natural sea un buen método de limpieza de estos acuíferos o de otros sistemas aluviales que presenten características hidrogeológicas y geoquímicas semejantes.

Jackson, R. E.

292

Responses of Riparian Cottonwoods to Alluvial Water Table Declines  

Microsoft Academic Search

Populus   species typically dominate riparian ecosystems throughout arid and semiarid regions of North American and efforts to minimize\\u000a loss of riparian Populus requires an integrated understanding of the role of surface and groundwater dynamics in the establishment of new, and maintenance\\u000a of existing, stands. In a controlled, whole-stand field experiment, we quantified responses of Populus morphology, growth, and mortality to

MICHAEL L. SCOTT; PATRICK B. SHAFROTH; GREGOR T. AUBLE

1999-01-01

293

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

294

The emerging roles of ARID1A in tumor suppression.  

PubMed

ARID1A has emerged as a tumor suppressor gene, which is mutated in a broad spectrum of cancers, especially in those arising from ectopic or eutopic endometrium. As a subunit of SWI/SNF chromatin remodeler, ARID1A facilitates target-specific binding of SWI/SNF complexes to chromatin, thereby altering the accessibility of chromatin to a variety of nuclear factors. In human cancer, ARID1A possesses not only features of a gatekeeper, regulating cell cycle progression, but also features of a caretaker, preventing genomic instability. An increasing body of evidence suggests crosstalk between ARID1A and PI3K/Akt pathways, and between ARID1A and p53. In this review, we discuss the spectrum of ARID1A alterations in cancers, tumor suppression mechanisms of ARID1A, oncogenic pathways cooperating with ARID1A, and clinical implications of ARID1A mutation. PMID:24618703

Wu, Ren-Chin; Wang, Tian-Li; Shih, Ie-Ming

2014-06-01

295

Stratigraphy and stable isotope results from an Eocene-Miocene section of the western Qaidam Basin, NW China  

NASA Astrophysics Data System (ADS)

The climate of central Asia has changed significantly throughout the Cenozoic, with surface uplift of the Himalaya and Tibetan Plateau cited as the primary cause of the change. However, the timing and mechanisms of plateau uplift, especially the northern plateau, is still unclear. Sedimentary basin deposits and their stable isotopic composition record both paleo-environment and paleoclimate information and thus can be used to study the climate evolution and ultimately-the surface uplift history. The Qaidam Basin, in the northern part of the Tibetan Plateau, deposited thick fluviolacustrine sediments from Eocene to Pleistocene time. Here, we report a newly documented 4440 m long sedimentary section near Huatugou town in the western Qaidam Basin, and preliminary O and C stable isotope results from sedimentary carbonates. The section includes four formations. Xiaganchaigou Formation (XGCG Fm), with a late Eocene age, is dominated by alluvial to fluvial conglomerates, sandstones and sandy mudstones in the lower part, and siltstones, mudstones with gypsum of lacustrine origin in the upper part. The Oligocene Shangganchaigou Formation (SGCG Fm) and early to middle Miocene Xiayoushashan Formation (XYSS Fm) both consist mainly of lacustrine mudstones, siltstones, sandstones, intercalated with marls, limestones and minor conglomerates. The late Miocene Shangyoushashan Formation (SYSS Fm, the lower part) is dominated by alluvial to delta-front conglomerates, gravelly sandstones and siltstones; paleosols with root traces are also common in this formation. Between 232 and 1196 m (XGCG Fm), both the ?18O (VPDB) and ?13C (VPDB) values of marls show large variability between -3.3 and -8.9‰ and between 0.7 and -2.7‰, respectively. Between 1196 and 2524 m (SGCG Fm), the ?18O values of marls and limestones show a more narrow range of lower values between -7.0 and -8.6‰, and the ?13C values decrease to between -1.5 and -4.9‰. We speculate that the large variability in XGCG Fm resulted from late Eocene climate cyclicity, followed by decreasing ? values related to global cooling during the Eocene-Oligocene transitions and cooling associated with the horizontal translation of the Basin to higher latitudes. From 2500 to 3500 m (XYSS Fm), there is a more pronounced decrease in the ?18O values of paleosols and carbonate cements to between -8.2 and -10.0‰, but their ?13C values show large variations between -0.6 and -6.8‰. A plausible explanation for these changes is localized climate perturbations associated with the growth of surrounding mountain ranges. At the top of the section, between 3500 and 4400 m (XYSS and SYSS Fm), both the ?18O and ?13C values of paleosols and carbonate cements show a positive shift by 1 to 2‰. This positive shift is interpreted as the result of mid-Miocene aridification, a regional climatic change event that was also documented in Tarim Basin, eastern Qaidam Basin, and in the northeastern Tibetan Plateau. Extreme aridity that is comparable to present day is not recorded in the Huatuguo section, most likely because these deposits predate the Plio-Pleistocene time period when modern conditions were established.

Li, L.; Garzione, C. N.; Pullen, A.; Chang, H.; Molnar, P. H.

2012-12-01

296

The deep channel and alluvial deposits of the Ohio Valley in Kentucky  

USGS Publications Warehouse

The alluvial deposits of Pleistocene age in the Ohio Valley form a ground-water reservoir of large storage capacity and yield. In this region it is the only source of large supplies of water that are both cool and of good quality the year round. The reservoir is heavily drawn upon, yet has very large potentialities for future development because of the favorable conditions for both natural and artificially induced infiltration of water from the river into the alluvial deposits. The principal features of the Ohio Valley were formed during the Pleistocene, or glacial, epoch. The drainage area upriver from Cincinnati was added when ice first advanced south, blocked rivers draining northwestward off the Appalachians, and diverted their waters southwest into the headwaters of the early Ohio River. A deep channel, the bottom of which is at a lower altitude than the present river bed, was excavated before the third (Illinoian) glacial stage. The thick body of sand and gravel that now lies in the deep channel was deposited by floods of melt water as the ice sheet of the Wisconsin stage melted away from the Ohio basin. The vertical distance between river pool level and the base of the old channel increases from 25 feet at Ashland, Ky., to 110 feet at the mouth of the river, for the old channel has a steeper gradient than the present river. The width of the bedrock valley ranges from half a mile at one point near Cincinnati to almost 10 miles near Uniontown, Ky. Where the valley is narrow, the flat-floored deep channel extends from one side of the valley to. the other. Where the valley is wide, the deep channel occupies only part of the width of the valley, the rest being underlain by rock benches mantled with alluvium. The alluvium consists of a sheet of sand and gravel overlain by a thinner layer of silt and clay. The sheet of sand and gravel is continuous across and up and down the valley, and at most places along the valley it is exposed in part of the river channel. The gravel is coarse and cobbly near Cincinnati but finer downstream, and near Paducah most of it is no larger than pea size. The thickness of water-saturated sand and gravel increases downvalley in the same way as does the distance between river level and the base of the old channel, roughly from 2b to 110 feet. The storage coefficient is likely to about 0.2, or 1.5 gallons of water per cubic foot of sand and gravel.

Walker, Eugene H.

1957-01-01

297

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

298

Alluvial fan and catchment initiation by rock avalanching, Owens Valley, California  

Microsoft Academic Search

The North Long John alluvial fan of the Inyo Mountains piedmont, Owens Valley, CA, was catastrophically initiated by a prehistoric (early Holocene?) rock avalanche. This avalanche resulted from the collapse and disintegration of the central part of a 1.1×2.0 km range front bedrock facet comprising the divide between the catchments of two large, adjoining alluvial fans. Failure rapidly produced and

Terence C Blair

1999-01-01

299

Influence of some physicochemical and biological parameters on soil structure formation in alluvial soils  

Microsoft Academic Search

This study examines the role of abiotic (texture, calcium carbonates or iron) and biotic parameters (earthworm and enchytraeid activities) on the initial phases of soil aggregation. Our research focused on humus forms in alluvial soils, which are considered as young and heterogeneous environments. We hypothesized that the soil structure formation is determined by both the nature of the recent alluvial

Géraldine Bullinger-Weber; Renée-Claire Le Bayon; Claire Guenat; Jean-Michel Gobat

2007-01-01

300

Physicochemical characteristics of the soils developed from alluvial deposits on Chongming Island in Shanghai, China  

Microsoft Academic Search

Characterization of the physico-chemical properties of the soils collected from Chongming Island in Shanghai, China, which is the largest alluvial island with a total area of about 1,070 km in the world, has been conducted in order to investigate the current status of agricultural soils, with special reference to the effect of alluvial deposits on the development and utilization of

Ming He; Katsutoshi Sakurai; Guoqing Wang; Zonghui Chen; Yi Shu; Jinjin Xu

2003-01-01

301

Sources and transport of nitrogen in arid urban watersheds.  

PubMed

Urban watersheds are often sources of nitrogen (N) to downstream systems, contributing to poor water quality. However, it is unknown which components (e.g., land cover and stormwater infrastructure type) of urban watersheds contribute to N export and which may be sites of retention. In this study we investigated which watershed characteristics control N sourcing, biogeochemical processing of nitrate (NO3-) during storms, and the amount of rainfall N that is retained within urban watersheds. We used triple isotopes of NO3- (?15N, ?18O, and ?17O) to identify sources and transformations of NO3- during storms from 10 nested arid urban watersheds that varied in stormwater infrastructure type and drainage area. Stormwater infrastructure and land cover--retention basins, pipes, and grass cover--dictated the sourcing of NO3- in runoff. Urban watersheds were strong sinks or sources of N to stormwater depending on runoff, which in turn was inversely related to retention basin density and positively related to imperviousness and precipitation. Our results suggest that watershed characteristics control the sources and transport of inorganic N in urban stormwater but that retention of inorganic N at the time scale of individual runoff events is controlled by hydrologic, rather than biogeochemical, mechanisms. PMID:24803360

Hale, Rebecca L; Turnbull, Laura; Earl, Stevan; Grimm, Nancy; Riha, Krystin; Michalski, Greg; Lohse, Kathleen A; Childers, Daniel

2014-06-01

302

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

303

Sustainable fresh water resources management in northern Kuwait---A remote sensing view from Raudatain basin  

Microsoft Academic Search

The paper presents time and cost effective remote sensing technology to estimate recharge potential of fresh water shallow aquifers for their sustainable management of water resources in arid ecosystem. Precipitation measurement of Raudatain basin in Kuwait from TRMM data has been made and integrated with geological, geomorphological and hyrological data, to estimate the recharge potential of this basin. The total

Saif Ud Din; Ahmad Al Dousari; Abdul Nabi Al Ghadban

2007-01-01

304

Sustainable fresh water resources management in northern Kuwait—A remote sensing view from Raudatain basin  

Microsoft Academic Search

The paper presents time and cost effective remote sensing technology to estimate recharge potential of fresh water shallow aquifers for their sustainable management of water resources in arid ecosystem. Precipitation measurement of Raudatain basin in Kuwait from TRMM data has been made and integrated with geological, geomorphological and hyrological data, to estimate the recharge potential of this basin. The total

Saif Ud Din; Ahmad Al Dousari; Abdul Nabi Al Ghadban

2007-01-01

305

Characterization of the hydrological functioning of the Niger basin using the ISBA-TRIP model  

Microsoft Academic Search

During the 70s and 80s, West Africa has faced extreme climate variations with extended extreme drought conditions. Of particular importance is the Niger basin, since it traverses a large part of the Sahel and is thus a critical source of water in this semi arid region. However, the understanding of the hydrological processes over this basin is currently limited by

V. Pedinotti; A. Boone; B. Decharme; J. F. Crétaux; N. Mognard; G. Panthou; F. Papa

2011-01-01

306

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

307

Managing water-use trade-offs in a semi-arid river delta to sustain multiple ecosystem services: a modeling approach  

Microsoft Academic Search

Managing trade-offs among water uses in a river basin to sustain multiple ecosystem services is crucial for adaptation to\\u000a changing river flow regimes. Here we analyze the trade-off between irrigation and fisheries in the Amudarya, a semi-arid river\\u000a basin in Central Asia, using an optimal control and an agent-based modeling approach. With the optimal control approach (OCA),\\u000a we identify the

Maja Schlüter; Heather Leslie; Simon Levin

2009-01-01

308

Band reporting rates of mallards in the Mississippi alluvial valley  

USGS Publications Warehouse

We captured 2,182 mallards (Anas platyrhynchos) in eastcentral Arkansas and marked 730 with standard bands, 728 with 10 reward bands, and 724 with 'dummy' radio transmitters during November 1986-89 to estimate band reporting rates in the Mississippi Alluvial Valley (MAV). Assuming all transmitters were reported, reporting rates were 0.16 (SE=0.049) for standard bands and 0.34 (SE=0.081) for 10 reward bands. Interviews with hunters indicated that flock size distributions differed (P=0.03) between mallards wearing transmitters and those wearing bands (standard or reward). Mallards wearing transmitters were more likely to be alone and less likely to be in large flocks when recovered than were mallards wearing bands. These results suggest that either band reporting rates of mallards in the MAV are substantially less than those of midcontinent mallards (P=0.03), or marking mallards with external transmitters increases susceptibility to hunting mortality.

Reinecke, K.J.; Shaiffer, C.W.; Delnicki, D.

1992-01-01

309

Chromium and nickel as indicators of source-to-sink sediment transfer in a Holocene alluvial and coastal system (Po Plain, Italy)  

NASA Astrophysics Data System (ADS)

A reliable quantitative estimate of changes in source-to-sink sediment transfer requires that high-resolution stratigraphic studies be coupled with accurate reconstructions of spatial and temporal variability of the sediment-routing system through time. Source-to-sink patterns from the contributing upland river catchments to the deltaic and coastal system are reconstructed from the Holocene succession of the Po Plain on the basis of selected geochemical indicators. Sediment supplied to the delta area by the major trunk river (the Po) exhibits naturally high Cr and Ni values, which invariably exceed the maximum permissible concentrations for unpolluted sites. This 'anomaly' reflects remarkable sediment contribution from ultramafic (ophiolitic) parent rocks cropping out in the Po drainage basin (Western Alps and NW Apennines). In contrast, alluvial and coastal plain deposits supplied by ophiolite-free, Apenninic catchments invariably display lower Cr and Ni contents. For constant sediment provenance domain, Cr and Ni distribution is observed to be controlled primarily by hydraulic sorting. Clay-silt deposits (floodplain, swamp and lagoon/bay facies associations) invariably show higher metal concentrations than their sandy counterparts (fluvial-channel, distributary-channel and beach-ridge facies associations). From a stratigraphic perspective, in sedimentary basins characterized by strong differences in sediment composition geochemical fingerprinting of individual facies associations framed by surfaces of chronostratigraphic significance is proposed as an invaluable approach towards an accurate quantitative assessment of sediment storage in alluvial and coastal depositional systems as opposed to volumetric reconstructions based on lithologic or geometric criteria alone.

Amorosi, Alessandro

2012-12-01

310

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

311

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

312

Late Neogene loess deposition in southern Tarim Basin: tectonic and palaeoenvironmental implications  

Microsoft Academic Search

Uplift of the Tibetan Plateau during the late Cainozoic resulted in a thick apron of molassic sediments along the northern piedmonts of the Kunlun and Altyn Mountains in the southern Tarim Basin. Early Neogene sediments are characterised by sandstone, siltstone and red mudstone, representing floodplain to distal alluvial fan environments. The Early Pliocene Artux Formation consists of medium-grained sandstone and

Hongbo Zheng; Chris McA Powell; Katherine Butcher; Junji Cao

2003-01-01

313

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

314

Water Through Life, A New Technique for Mapping Shallow Water Tables in Arid and Semi-Arid Climates using Color Infrared Aerial Photographs  

NASA Astrophysics Data System (ADS)

Two of the fundamental issues in water resources in arid regions are (1) the ability to accurately predict the presence of groundwater shallow enough to support riparian ecosystems and (2) the ability to assess the vulnerability of those ecosystems to withdrawals by an ever-increasing human population. A new technique for finding areas of shallow groundwater in arid and semi-arid environments has been developed that addresses both of these concerns by using the relative health of natural vegetation as an indicator of perennial shallow groundwater in environments where water is the main biolimiting factor to growth. The technique revolves around the differences in the spectral response between: actively transpiring vegetation; dormant vegetation; and dry, bare soil in the 400-900nm range as recorded by color infrared film in the dry pre-monsoon months. Distilling out only the active vegetation from aerial photographs was achieved through the creation of an index-based filter using readily available, inexpensive photo processing software. The output of the filter was carefully designed to maximize the qualitative interpretability by an analyst through the careful selection of display colors that are tuned to the maximum sensitivity range of the human vision system. When the analyst combines the qualitative interpretation of the spatial distribution of active vegetation with an understanding of the rooting depth of the native species it becomes possible to extrapolate a quantitative, basin-scale reconnaissance level map which defines the lateral extent of areas of shallow <20m(+/-5m) groundwater with a spatial accuracy of just a few meters. The research plan for the development of this technique also explored the potential for conducting the entire analysis procedure in three dimensions by projecting the filtered aerial photographs onto 10m resolution Digital Elevation Models (DEMs). When this is done and the geomorphology of the region is carefully considered the usefulness of the technique becomes greatly enhanced. By extending the analysis from 2D to 3D, the technique evolves from being a powerful descriptive tool for mapping the lateral extent of shallow groundwater into a very powerful predictive tool that can aid in unlocking the dynamics of shallow aquifers and groundwater flow regimes within basins in arid and semi-arid climates.

Fielding, G.

2003-04-01

315

Architectural analysis and chronology of an Alpine alluvial fan using 3D ground penetrating radar investigation and quantitative outcrop analysis  

NASA Astrophysics Data System (ADS)

Alluvial fans represent sediment sinks directly at the outlet of the source area in mountain landscapes. They contain multiple information on short-term as well as on long-term changes of sediment supply and of environmental parameters like climate and vegetation. However, most studies on alluvial fans are restricted to selective surface analysis and almost no studies exist which aim to clear the subsurface geometry of an alluvial fan in total. Our study is embedded in the SedyMONT research program within the TOPO-EUROPE framework and aims to clarify the subsurface structure of an alluvial fan by a time-controlled 3D architectural model. The Illgraben fan is located in the Central Alps of Switzerland within the Rhone valley and covers an area of about 6.5 km2. Currently construction works for a highway cuts through the fan exposing its deposits (mainly gravel and diamicton) up to 15 m depth and therefore offers the unique opportunity to link ground penetrating radar (GPR) investigations with quantitative outcrop analysis. GPR measurements on the Illgraben fan have been carried out at two different scales: (i) a fan-wide scale with about 80 km radar sections forming a half spiderweb pattern to identify the fundamental architecture of the fan (using 100 MHz and 40 MHz antenna), and (ii) four orthogonal grids of about 50 m x 100 m for detailed architectural analysis (using a 200 MHz antenna). Penetration depth was up to 15 m for high and low frequency antennas. The radargrams were processed, georeferenced and transferred into a 3D-modeling software (GOCAD®) to map radar facies units. By means of quantitative sedimentological analyses and precisely scaled photo panels we could translate radar facies pattern into sedimentary facies, and interpret reflectors and their properties in terms of sedimentary units. These geobodies can be characterized in terms of volume, shape, geometrical key parameters, their spatial distribution, as well as internal sedimentary structures in order to identify depositional processes. Preliminary results show distinct horizons ('palaeosurfaces') indicating fan-wide depositional starvation and minimized sediment supply. Furthermore, between these horizons the Illgraben fan is built up by multi-storey and multilateral architectural elements of different type and at characteristic scales which can be attributed to specific depositional processes (e.g. debris flows, channel fills, levees). At small-scale a heterogeneous and complex stacking pattern of geobody interfaces was observed, showing a distinct multi-fold hierarchy of mainly concave, convex and horizontal structures. First 14C AMS ages from the central part of the alluvial fan (ca. 10 m depth) indicate high sedimentation rates during the past 2000 years. We found no control of natural spectral gamma-ray radiation by lithofacies units. Hence variations must indicate changes in the source areas and/or climate-controlled weathering conditions in the drainage basin (ca. 9.5 km2).

Franke, D.; Hornung, J.; Hinderer, M.

2012-04-01

316

Depositional setting and diagenetic evolution of some Tertiary unconventional reservoir rocks, Uinta Basin, Utah.  

USGS Publications Warehouse

The Douglas Creek Member of the Tertiary Green River Formation underlies much of the Uinta basin, Utah, and contains large volumes of oil and gas trapped in a complex of fractured low-permeability sandstone reservoirs. In the SE part of the basin at Pariette Bench, the Eocene Douglas Creek Member is a thick sequence of fine- grained alluvial sandstone complexly intercalated with lacustrine claystone and carbonate rock. Sediments were deposited in a subsiding intermontane basin along the shallow fluctuating margin of ancient Lake Uinta. Although the Uinta basin has undergone postdepositional uplift and erosion, the deepest cored rocks at Pariette Bench have never been buried more than 3000m.-from Authors

Pitman, J. K.; Fouch, T. D.; Goldhaber, M. B.

1982-01-01

317

Stochastic modelling of an heterogeneous porous media: the Komadougu Yobe alluvial aquifer, Lake Chad basin  

Microsoft Academic Search

The downstream Komadugu Yobe river valley, a Lake Chad tributary straddling the Niger-Nigeria border, is an area of well-developed irrigated cropping. Increasing pressure on both surface water and groundwater resources require a better understanding of the hydrogeological processes, changing water balance and aquifer vulnerability. The upper part of the aquifer is made up of fine sand matrix with numerous clay

M. Le Coz; P. Genthon; G. Favreau

2009-01-01

318

Stochastic modelling of an heterogeneous porous media: the Komadougu Yobe alluvial aquifer, Lake Chad basin  

NASA Astrophysics Data System (ADS)

The downstream Komadugu Yobe river valley, a Lake Chad tributary straddling the Niger-Nigeria border, is an area of well-developed irrigated cropping. Increasing pressure on both surface water and groundwater resources require a better understanding of the hydrogeological processes, changing water balance and aquifer vulnerability. The upper part of the aquifer is made up of fine sand matrix with numerous clay lenses. Such facies heterogeneities influence flow and transport in the subsurface and need to be taken into account for hydrogeological modelling. To this goal, the origin of these heterogeneities was first examined; secondly, a methodology to describe the structure of the media by means of a stochastic simulation procedure is suggested. Drilling in the unsaturated zone (~ 0-10 m) and granulometric analysis of sediments showed that clay lenses in the Komadugu valley have two main sources. On the one hand, lenses can be due to the filling of abandoned channel resulting from meander cut-off and have then a specific, elongated geometry. On the other hand, they can correspond to overbank deposits formed on floodplains and have less predictable shape and extent. Cell-based geostatistical simulation methods are commonly used for facies modelling but are inefficient when deposits have complex variation patterns such channel fill deposits. Object-based simulation methods should be more relevant but require a clear knowledge of object geometries. In the study area, complex variation patterns would rule out the cell-based approach whereas overbank deposits may limit the relevance of object based simulations. A facies modelling via image analysis and multiple point statistic simulations was therefore initiated. In a first step, available hard data (geological logs, satellite images) together with soft constraints arising from the general geological knowledge of the area were used to generate synthetic images of the heterogeneous media. A second step will consist in the calculation of statistical relations between multiple location considered jointly based on these images. Finally, conditional simulations of the upper part of the aquifer will be computed by means of these statistical relations.

Le Coz, M.; Genthon, P.; Favreau, G.

2009-04-01

319

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

320

BARRIERS TO WATER CONSERVATION IN THE RIO GRANDE BASIN1  

Microsoft Academic Search

The Rio Grande basin shares problems faced by many arid regions of the world: growing and com- peting demands for water and river flows and uses that are vulnerable to drought and climate change. In recent years legislation, administrative action, and other measures have emerged to encourage private investment in efficient agricultural water use. Nevertheless, several institutional barriers discourage irrigators

Frank A. Ward; Ari M. Michelsen; Leeann DeMouche

2007-01-01

321

Historical Sagebrush Establishment Practices in the Powder River Basin  

Microsoft Academic Search

The Powder River Basin of Wyoming is a semi-arid area dominated by sagebrush grassland vegetation communities. This region includes 15 surface coal mines. Reclamation of mined lands requires re-establishment of native species to meet the post mine land use. The Wyoming Department of Environmental Quality (WDEQ) serves as the regulatory authority for the State's surface coal mines. Wyoming statutes require

Laurel E. Vicklund

322

Three-dimensional geologic mapping of the Cenozoic basin fill, Amargosa Desert basin, Nevada and California  

USGS Publications Warehouse

Understanding the subsurface geologic framework of the Cenozoic basin fill that underlies the Amargosa Desert in southern Nevada and southeastern California has been improved by using borehole data to construct three-dimensional lithologic and interpreted facies models. Lithologic data from 210 boreholes from a 20-kilometer (km) by 90-km area were reduced to a limited suite of descriptors based on geologic knowledge of the basin and distributed in three-dimensional space using interpolation methods. The resulting lithologic model of the Amargosa Desert basin portrays a complex system of interfingered coarse- to fine-grained alluvium, playa and palustrine deposits, eolian sands, and interbedded volcanic units. Lithologic units could not be represented in the model as a stacked stratigraphic sequence due to the complex interfingering of lithologic units and the absence of available time-stratigraphic markers. Instead, lithologic units were grouped into interpreted genetic classes, such as playa or alluvial fan, to create a three-dimensional model of the interpreted facies data. Three-dimensional facies models computed from these data portray the alluvial infilling of a tectonically formed basin with intermittent internal drainage and localized regional groundwater discharge. The lithologic and interpreted facies models compare favorably to resistivity, aeromagnetic, and geologic map data, lending confidence to the interpretation.

Taylor, Emily M.; Sweetkind, Donald S.

2014-01-01

323

Alluvial fan dynamics in the El'gygytgyn Crater: implications for the 3.6 Ma old sediment archive  

NASA Astrophysics Data System (ADS)

A sedimentological program has been conducted using frozen core samples from the 141.5 m long El'gygytgyn 5011-3 permafrost well. The drill site is located in sedimentary permafrost west of the lake that partly fills the El'gygytgyn Crater. The total core sequence is interpreted as strata building up a progradational alluvial fan delta. Four structurally and texturally distinct sedimentary units are identified. Unit 1 (141.5-117.0 m) is comprised of ice-cemented, matrix-supported sandy gravel and intercalated sandy layers. Sandy layers represent sediments which rained out as particles in the deeper part of the water column under highly energetic conditions. Unit 2 (117.0-24.25 m) is dominated by ice-cemented, matrix-supported sandy gravel with individual gravel layers. Most of the unit 2 diamicton is understood to result from alluvial wash and subsequent gravitational sliding of coarse-grained material on the basin slope. Unit 3 (24.25-8.5 m) has ice-cemented, matrix-supported sandy gravel that is interrupted by sand beds. These sandy beds are associated with flooding events and represent near-shore sandy shoals. Unit 4 (8.5-0.0 m) is ice-cemented, matrix-supported sandy gravel with varying ice content, mostly higher than below. It consists of slope material and creek fill deposits. The uppermost meter is the active layer into which modern soil organic matter has been incorporated. The nature of the progradational sediment transport taking place from the western and northern crater margins may be related to the complementary occurrence of frequent turbiditic layers in the central lake basin as is known from the lake sediment record. Slope processes such as gravitational sliding and sheet flooding that takes place especially during spring melt are thought to promote mass wasting into the basin. Tectonics are inferred to have initiated the fan accumulation in the first place and possibly the off-centre displacement of the crater lake.

Schwamborn, G.; Fedorov, G.; Ostanin, N.; Schirrmeister, L.; Andreev, A.; El'gygytgyn Scientific Party, the

2012-06-01

324

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

325

Tectonics and Quaternary sequence development of basins along the active Vienna Basin strike-slip fault  

NASA Astrophysics Data System (ADS)

The Vienna Basin strike-slip fault is a continent scale active fault extending over a distance of some 300 km from the Eastern Alps through the Vienna Basin into the Western Carpathians. Sinistral movement causes the formation of several tight Pleistocene strike-slip basins within the older Miocene Vienna Basin. These sub-basins not only have a high relevance for groundwater exploitation but their fault activities depict serious seismic hazards. Basins are filled with fluvial sediments from the Danube and, closer to the Alpine front, with thick alluvial fan deposits. However, knowledge on the stratigraphy and tectonics is sparse and rather limited to the Miocene part of the Vienna Basin as it hosts giant hydrocarbon fields. This study tackles two major questions: (i) What is the effect of Quaternary climatic oscillations and subsidence on the sequence development of the alluvial fans and (ii) what is the deformation style of these basins? To answer (i) we present a series of new OSL ages and biotic data from both, surface and cores, to better constrain the timing of fan activity, fan abandonment but also to constrain the onset of Pleistocene basin formation. For (ii) we utilize information from unparalleled geophysical and geological data. Specifically we utilize industrial Bouguer gravity's derivatives to highlight shallow structures and to compensate for the lag of fault trace information. The integration of geological and geophysical data highlights textbook-like models of strike-slip basins, with typical features like Riedel shears with intervening relay ramps, en-echelon sidewall faults and a cross-basin fault zone delimiting opposite depocenters. The infill reflects a distinct cyclicity with thick sequences of coarse sediments deposited during colder periods and thin sequences of paleosol and flood sediments deposited during warmer periods. Ages indicate main activity around the short peak glacial periods and basin formation starting c. 300 ka ago. The distinct sequence development and the strong contrast to the underlying marine deposits is a very suitable setting to apply geophysical methods constraining basins' deformation style.

Salcher, B.; Lomax, J.; Meurers, B.; Smit, J.; Preusser, F.; Decker, K.

2012-04-01

326

Residence Time of Sediments in Alluvial Plains from U-Th Isotope Analyses: The Ganges River System. (Invited)  

NASA Astrophysics Data System (ADS)

As illustrated in recent studies (Granet et al., 2007 ; 2010), the analysis of U-Th disequilibria in sediments collected along rivers allows the estimation of sediment transfer time in alluvial plains. Such an approach requires understanding the secondary processes which modify the U and Th isotopes of the sediments during their transfer within the plain. It also assumes a negligible contribution of new and fresh sediments coming from the erosion of the plain substratum during the sedimentary transfer. In order to specify these first results on the Ganges Basin river system, the main Himalayan tributaries of the Ganges were sampled at the exit of the Himalayan range and at the outlet of their watershed just before their confluence with the Ganges. In addition, at several sampling locations, suspended sedimentary load was collected at different depths of the water column. Our new data along with previously published data in (Granet et al., 2007 ; 2010) show that a wide range of variation in Th activity ratios in bedload and suspended sediments for several of these rivers. Such differences probably point to contrasting (geographical, geological, lithological, pedological..) origins of these two types of sediments. Furthermore, bedload and suspended load exhibit very different covariations of U and Th isotope ratios from upstream to downstream. These different trends of variations highlight the occurrence of different transfer histories within the plain for the coarse-grained and fine-grained sediments: 100 ky or more for the bedload sediments from the Himalayan range to the confluence with the Ganges, but much less for the suspended sediments. Variations in the U-Th isotope ratios of suspended sediments recorded for the same sampling location but at different seasons suggest that their transfer time could be as fast as one year. These data therefore confirm the real potential of U and Th isotopes in river sediments to constrain their transfer time within alluvial plain but also their origin. M. Granet et al. (2007) time-scales of sedimentary transfer and weathering processes from U-series nuclides: Clues from the Himalayan rivers, Earth and Planet. Sc. Let., 261, 389-406. Granet M et al. (2010) U-series disequilibria in suspended river sediments and implication for sediment transfer time in alluvial plains : the case of the Himalayan rivers Geochim. Cosmochim. Acta, 74, 2851-2865

Chabaux, F. J.; Blaes, E.; Granet, M.; Dosseto, A.; Stille, P.; France-Lanord, C.; Lupker, M.

2010-12-01

327

Effects of soil and vegetation on runoff along a catena in semi-arid Spain  

NASA Astrophysics Data System (ADS)

Runoff and infiltration were investigated on abandoned fields of patchy vegetation in semi-arid Spain during 15 months of natural rainfall and by rainfall simulations. The aim was to ascertain sources and sinks of runoff and the effects of soils and plant cover. Soils of the catena developed from mica schists of the upper hillslopes, fan deposits of the lower hillslopes, and an alluvial terrace at the bottom. Runoff from natural events were from three sets of three pairs each of 10 × 2 m runoff plots. The pairs of each set had different densities of plant cover; the sets were vegetated with tussock grass, Stipa tenacissima, a shrub, Anthyllis cytisoides, and a bush, Retama sphaerocarpa. Nineteen natural rainfall events of intensities up to 18 mm/h produced 400 mm of rain during the study period. Because the rainfall threshold for runoff production was about 20 mm, only eight events produced runoff. The rainfall simulations used a sprinkler that produced 50 mm/h of rain for 30 minutes; runoff was recorded each minute in 0.24 m 2 bounded plots. The depth and structure of the soil mantle provide the main controls on runoff rates, which are lowest on the lower fan deposits and highest on the thin upslope soils. The river-bank terrace, with a surface covered by crusts and mosses, also yields relatively high runoff. In general, vegetation density varies inversely with runoff. Nevertheless, shrub and bush litter favor runoff, as does a particular spatial distribution of individual plants on the hillslope. Settling of the upper few centimeters of soils of the alluvial fan following cessation of cultivation 15 to 40 years ago has produced a near-surface compacted layer favoring shallow subsurface runoff. Apparently contradictory results between runoff plots and rainfall simulations are the result of differing processes.

Nicolau, J. M.; Solé-Benet, A.; Puigdefábregas, J.; Gutiérrez, L.

1996-01-01

328

A WATER RESOURCES PROTECTION METHOD AND ITS APPLICATION TO ARID AND SEMI-ARID MINING AREAS  

Microsoft Academic Search

The Shendong coal mine, located in mid-western China, has specific hydrogeological and mining conditions from which a water resources protection method has been developed. It is proposed that this method can be applied to other arid and semi-arid mining areas. Based on analysis of the hydrogeological structure, the characteristics of groundwater-producing fracture zones in overburden rocks, the stability of the

SUN YAJUN; LIU YONG; WANG CHANGSHEN; XU ZHIMIN; SHAO FEIYAN; JIANG SU

329

30 CFR 903.822 - Special performance standards-Operations in alluvial valley floors.  

Code of Federal Regulations, 2013 CFR

...RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE ARIZONA § 903.822 Special performance standardsâOperations in alluvial valley floors. Part 822 of this chapter,...

2013-07-01

330

44 CFR 65.13 - Mapping and map revisions for areas subject to alluvial fan flooding.  

Code of Federal Regulations, 2013 CFR

...INSURANCE AND HAZARD MITIGATION National Flood Insurance Program IDENTIFICATION...recognize on a NFIP map that a structural flood control measure provides protection from the base flood in an area subject to alluvial...

2013-10-01

331

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...

332

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

333

Alluvial architecture of fluvio-deltaic successions: a review with special reference to Holocene settings  

Microsoft Academic Search

Alluvial architecture has been subject of many studies because of the occurrence of natural resources in ancient fluvial successions. This paperprovides an overview of the current state of research on alluvial architecture with special reference to Holocene fluvio-deltaic settings. Severalexamples from modern fluvio-deltaic areas, especially the Holocene Rhine-Meuse delta (the Netherlands) and the Lower Mississippi Valley(U.S.A.), are used to illustrate

M. J. P. Gouw

2007-01-01

334

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

335

Impacts of Land Use and Degradation on the Hydrology of a Semi-Arid Catchment  

NASA Astrophysics Data System (ADS)

The hydrology of small and medium-sized catchments can drastically be modified due to changes in land use and degradation (LUD). Normally, distributed hydrological models (DHMs) have been used to study the effects of such changes on runoff response at basin scale, which is fundamental e.g. for streamflow forecasts. However, the applicability of DHMs to arid and semi-arid catchments may not be straightforward due to i) generally sparse data, and high spatial variability, of surface and subsurface systems and ii) poor hydrologic monitoring system (e.g. rainfall and runoff). The objective of this work is to use the WASA-SED model, a semi-distributed model, to detect the influence of LUD on the streamflow generation of a medium-sized catchment in Semi-arid Northeastern Brazil. In order to accomplish this goal, the model is run for two scenarios: one with degraded lands and another one without them. Then, the WASA-SED model based on these two scenarios is simulated for different realizations of the main model parameters. The application of the WASA-SED model comprises large uncertainties arising mainly from model input and distributed parameters. However, the model runs corresponding to the degraded lands scenario produce the best results according to the chosen performance criteria.

Cunha Costa, Alexandre; Sávio Martins, Eduardo; Carvalho, Margareth S. B. S.; Silva, Robson Franklin

2014-05-01

336

Constraining aggradation and degradation phases of alluvial fans in the sedimentary record: a case study from the Namib Desert, NW Namibia  

NASA Astrophysics Data System (ADS)

Controversy exists over when alluvial fans propagate, when they incise and how this is expressed in the sedimentary record. The Horingbaai Fan-delta at the Skeleton coast provides an end member due to its location in a hyper-arid area and a tectonically quiescent, although continuously uplifting setting. Accordingly, the influence of climate changes on alluvial fan sedimentation is directly assessable. There is pronounced interaction with the marine system during fan evolution, which provides the opportunity to constrain phases of fan progradation based on marine terrace stratigraphy. In this contribution, we will (1) present a detailed stratigraphic framework of the Horingbaai Fan-delta and associated marine terraces, and (2) analyze this framework in order to identify the imprint of past climatic changes on the sedimentary record. The of the Horingbaai Fan-delta sediments have been laid down between 2.6 and 2.4 Ma, based on age constraints from under- and overlying marine terraces. After 2.4 Ma, fan sedimentation was generally reduced and much more irregular due to intervening erosion phases. We propose a new model for late stage sedimentation and erosion phases, using offshore bathymetric and onshore sedimentological data, and conclude that generally decreasing sea-surface temperatures and glacial cycles largely govern the mode of sedimentation since the Early Pleistocene. We compare these findings to other fans at the Skeleton Coast, as well as other systems worldwide. Our study shows that climatic variations may leave distinct imprints in the sedimentological record. Recognizing these in depositional systems worldwide will improve understanding how fan sediments are preserved through time, and whether the reported worldwide increase in sedimentation rates since the Late Cenozoic is real or apparent.

von Hagke, Christoph; Stollhofen, Harald; Malatesta, Luca C.; Stanistreet, Ian

2014-05-01

337

Cool, wet conditions late in the Younger Dryas in semi-arid New Mexico  

NASA Astrophysics Data System (ADS)

A thick alluvial sequence in central New Mexico contains the Scholle wet meadow deposit that traces upstream to a paleospring. The wet meadow sediments contain an abundant fauna of twenty-one species of freshwater and terrestrial mollusks and ten species of ostracodes. The mollusks and ostracodes are indicative of a local high alluvial water table with spring-supported perennial flow but without standing water. Pollen analysis documents shrub grassland vegetation with sedges, willow, and alder in a riparian community. Stable carbon isotopes from the wet meadow sediments have ? 13C values ranging from - 22.8 to - 23.3‰, indicating that 80% of the organic carbon in the sediment is derived from C 3 species. The wet meadow deposit is AMS dated 10,400 to 9700 14C yr BP, corresponding to 12,300 to 11,100 cal yr BP and overlapping in time with the Younger Dryas event (YD). The wet meadow became active about 500 yr after the beginning of the YD and persisted 400 yr after the YD ended. The Scholle wet meadow is the only record of perennial flow and high water table conditions in the Abo Arroyo drainage basin during the past 13 ka.

Hall, Stephen A.; Penner, William L.; Palacios-Fest, Manuel R.; Metcalf, Artie L.; Smith, Susan J.

2012-01-01

338

GLDAS Land Surface Models based Aridity Indices  

NASA Astrophysics Data System (ADS)

Identification of dryland areas is crucial to guide policy aimed at intervening in water stressed areas and addressing its perennial livelihood or food insecurity. Aridity indices based on spatially relative soil moisture conditions such as NCEP aridity index allow cross comparison of dry conditions between sites. NCEP aridity index is based on the ratio of annual precipitation (supply) to annual potential evaporation (demand). Such an index ignores subannual scale competition between evaporation and drainage functions well as rainfall and temperature regimes. This determines partitioning of annual supply of precipitation into two competing (but met) evaporation and runoff demands. We here introduce aridity indices based on these additional considerations by using soil moisture time series for the past 3 decades from three Land Surface Models (LSM) models and compare it with NCEP index. We analyze global monthly soil moisture time series (385 months) at 1 x 1 degree spatial resolution as modeled by three GLDAS LSMs - VIC, MOSAIC and NOAH. The first eigen vector from Empirical Orthogonal Function (EOF) analysis, as it is the most dominant spatial template of global soil moisture conditions, is extracted. Frequency of nonexceedences of this dominant soil moisture mode for a location by other locations is calculated and is used as our proposed aridity index. An area is indexed drier (relative to other areas in the world) if its frequency of nonexceedence is lower. The EOF analysis reveals that their first eigen vector explains approximately 32%, 43% and 47% of variance explained by first 385 eigen vectors for VIC, MOSAIC and NOAH respectively. The temporal coefficients associated with it for all three LSMS show seasonality with a jump in trend around the year 1999 for NOAH and MOSAIC. The VIC aridity index displays a pattern most closely resembling that of NCEP though all LSM based indices isolate dominant dryland areas. However, all three LSMs identify some parts of south central Africa, southeast United States and eastern India as drier than NCEP classification. NOAH and MOSAIC indentify parts of Western Africa drier than the other two classifications, while NOAH and VIC indentify parts of central India as wetter than the other two classifications.

Pande, S.; Ghazanfari, S.

2011-12-01

339

Water and Arid Lands of the Western United States  

NASA Astrophysics Data System (ADS)

Despite impressive innovations by some states, western water laws and institutions now in place were designed chiefly for an earlier era and have not adapted to the new demands and stresses on water resources. In Water and the Arid Lands of the Western United States the authors explore the nature of water demands in the agricultural and municipal sectors and set forth prescriptions for the west to move away from its historical reliance on expensive supply-side projects and toward better management of existing supplies. Six cases studies by experts in the field illustrate specific examples of water management issues. Taking as foci the Central Valley of California, the High Plains of Texas, and the Upper Basin of the Colorado River, three of the case studies examine problems faced by the large urban areas of southern California; Tucson, Arizona; and Denver, Colorado. A concluding chapter suggests practical policy options and politically feasible institutional changes for maximizing the efficiency of water use and minimizing the conflict associated with the reallocation of limited water supplies.

El-Ashry, Mohamed T.; Gibbons, Diana C.

1988-09-01

340

Calculations of surface radiation in arid regions - A case study  

NASA Technical Reports Server (NTRS)

The surface and satellite data measured during the preliminary field experiment for the Land-Atmosphere Interactions Experiment conducted at the Heihe River basin in western China are used to investigate the difficulties encountered in the derivation of the surface radiation budget in arid regions. The surface radiation is derived by coupling theoretical radiative transfer calculations with satellite cloud retrievals. For cloud-free cases, the modeled downward solar fluxes are systematically larger than the measured fluxes. It is found that the error can be reduced and that good agreement between the computed and measured surface solar fluxes can be obtained by using an aerosol single-scattering albedo of 0.5 and an optical thickness of about 0.2 in the afternoon hours. For all the cases studied when both surface and satellite data are available, the mean errors are 4.3 and -4.7 W/sq m for the net downward surface solar flux and the downward surface IR flux, respectively. The rms errors are 17.4 and 22.1 W/sq m for the respective surface fluxes. The importance of aerosols in surface radiation calculations is underscored.

Chou, Ming-Dah; Ji, Guoliang; Liuo, Kuo-Nan; Ou, Szu-Cheng S.

1992-01-01

341

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

342

Provenance of alluvial fan deposits to constrain the mid-term offsets along a strike-slip active fault: the Elsinore fault in the Coyote Mountains, Imperial Valley, California.  

NASA Astrophysics Data System (ADS)

The lateral variation in rates along a fault and its constancy along time is a matter of discussion. To give light to this discussion, short, mid and long term offset distribution along a fault is needed. Many studies analyze the short-term offset distribution along a strike-slip fault that can be obtained by the analysis of offset features imprinted in the morphology of the near-fault area. We present an example on how to obtain the mid- to long-term offset values based on the composition of alluvial fans that are offset by the fault. The study area is on the southern tip of the Elsinore fault, which controls the mountain front of the Coyote Mountains (California). The Elsinore-Laguna Salada fault is part of the San Andreas fault (SAF) system, extending 250 km from the Los Angeles Basin southeastward into the Gulf of California, in Mexico. The slip-rate on the southern Elsinore fault is believed to be moderate based on recent InSAR observations, although a recent study near Fossil Canyon (southern Coyote Mountains) suggests a rate in the range of 1-2 mm/yr. For this study we processed the airborne LiDAR dataset (EarthScope Southern & Eastern California, SoCal) to map short to mid-term alluvial offsets. We reprocessed the point clouds to produce DEMs with 0.5m and 0.25m grids and we varied the insolation angles to illuminate the various fault strands and the offset features. We identified numerous offset features, such as rills, channel bars, channel walls, alluvial fans, beheaded channels and small erosional basins that varied in displacement from 1 to 350 m. For the mid- to long-term offsets of the alluvial fans we benefited from the diverse petrological composition of their sources. Moreover, we recognized that older alluvium, which is offset by greater amounts, is in some cases buried beneath younger alluvial fan deposits and separated by buried soils. To determine the source canyon of various alluvial elements, we quantified the clast assemblage of each source basin and each alluvial fan on both sides of the fault. To accomplish this, we used a portable grid and classified more than 300 clasts at each of more than 90 sites along the fault. We found a very good fit between displaced alluvial fan elements and their inferred source canyons, but a poor match with the alluvium from neighboring canyons, which allows us to resolve the long-term offset. Planned dating of the pedogenic carbonate associated with these buried soils will allow the resolution of the mid- to long-term slip rates over multiple time frames to test the constancy of fault slip rate during the late Quaternary, as well as to test the lateral variations in rate along the fault.

Masana, Eulalia; Stepancikova, Petra; Rockwell, Thomas

2013-04-01

343

Facies architecture and paleohydrology of a synrift succession in the Early Cretaceous Choyr Basin, southeastern Mongolia  

USGS Publications Warehouse

The Choyr Basin is one of several Early Cretaceous rift basins in southwestern Mongolia that developed in specific regions between north-south trending fold-and-thrust belts. The eastern margin of the basin is defined by high-angle normal and/or strike-slip faults that trend north-to-south and northeast-to-southwest and by the overall geometry of the basin, which is interpreted to be a half graben. The sedimentary succession of the Choyr Basin documents one of the various types of tectono-sedimentary processes that were active in the rift basins of East Asia during Early Cretaceous time. The sedimentary infill of the Choyr Basin is newly defined as the Khalzan Uul and Khuren Dukh formations based on detailed mapping of lateral and vertical variations in component lithofacies assemblages. These two formations are heterotopic deposits and constitute a third-order fluvio-lacustrine sequence that can be divided into transgressive and highstand systems tracts. The lower part of the transgressive systems tract (TST) is characterized by sandy alluvial-fan and braided-river systems on the hanging wall along the western basin margin, and by a gravelly alluvial-fan system on the footwall along the eastern basin margin. The alluvial-fan and braided-river deposits along the western basin margin are fossiliferous and are interpreted to have developed in association with a perennial fluvial system. In contrast, alluvial-fan deposits along the eastern basin margin do not contain any distinct faunas or floras and are interpreted to have been influenced by a high-discharge ephemeral fluvial system associated with fluctuations in wetting and drying paleohydrologic processes. The lower part of the TST deposit fines upward to siltstone-dominated flood-plain and ephemeral-lake deposits that constitute the upper part of the TST and the lower part of the highstand systems tract (HST). These mudstone deposits eventually reduced the topographic irregularities typical of the early stage of synrift basin development, with an associated decrease in topographic-slope gradients. Finally, a high-sinuosity meandering river system drained to the south during the late highstand stage in response to the northward migration of the depocenter. The upper HST deposits are also fossiliferous and are interpreted to have been influenced by a perennial fluvial system, although the average annual discharge of this system was probably less than 5 percent of that involved in the formation of the lower TST deposits along the western basin margin. ?? 2006 Elsevier Ltd. All rights reserved.

Ito, M.; Matsukawa, M.; Saito, T.; Nichols, D. J.

2006-01-01

344

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

Leyden, Barbara W.

1984-01-01

345

Mineral Occurrence, Translocation, and Weathering in Soils Developed on Four Types of Carbonate and Non-carbonate Alluvial Fan Deposits in Mojave Desert, Southeastern California  

NASA Astrophysics Data System (ADS)

Soil geomorphology and mineralogy can reveal important clues about Quaternary climate change and geochemical process occurring in desert soils. We investigated (1) the mineral transformation in desert soils developed on four types of alluvial fans (carbonate and non-carbonate) under the same c