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The amount and spatial distribution of deep drainage (downward movement of water across the bottom of the root zone) and groundwater recharge affect the quantity and quality of increasingly limited groundwater in arid and semiarid regions. We synthesize research from the fields of ecology and hydrology to address the issue of deep drainage in arid and semiarid regions. We start with a recently developed hydrological model that accurately simulates soil water potential and geochemical profiles measured in thick (.50 m), unconsolidated vadose zones. Model results indicate that, since the climate change that marked the onset of the Holocene period 10 000–15 000 years ago, there has been no deep drainage in vegetated...
Global synthesis of the findings from �140 recharge study areas in semiarid and arid regions provides important information on recharge rates, controls, and processes, which are critical for sustainable water development. Water resource evaluation, dryland salinity assessment (Australia), and radioactive waste disposal (US) are among the primary goals of many of these recharge studies. The chloride mass balance (CMB) technique is widely used to estimate recharge. Average recharge rates estimated over large areas (40?374 000 km2) range from 0�2 to 35 mm year1, representing 0�1?5% of long-term average annual precipitation. Extreme local variability in recharge, with rates up to �720 m year1, results from focussed...
Humans have exerted large-scale changes on the terrestrial biosphere, primarily through agriculture; however, the impacts of such changes on the hydrologic cycle are poorly understood. The purpose of this study was to test the hypothesis that the conversion of natural rangeland ecosystems to agricultural ecosystems impacts the subsurface portion of the hydrologic cycle by changing groundwater recharge and flushing salts to underlying aquifers. The hypothesis was examined through point and areal studies investigating the effects of land use/land cover (LU/LC) changes on groundwater recharge and solute transport in the Amargosa Desert (AD) in Nevada and in the High Plains (HP) in Texas, US. Studies use the fact that...
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This USGS Data Release represents Soil-Water Balance (SWB) groundwater recharge modeling results for the Upper Colorado River Basin (UCRB). The data release was produced in compliance with 'open data' requirements as a way to make the scientific products associated with USGS research efforts and publications available to the public. This dataset comprises SWB model results from runs using projected climate data, summarized by sub-basin on a monthly basis, and there are 4 separate datafiles associated with this Data Release: 1. SWB model results for actual evapotranspiration (AET), summarized by sub-basin on a monthly basis from 1950 through 2099 2. SWB model results for potential evapotranspiration (PET), summarized...
Summary Tritium and bromide were used as applied tracers to determine groundwater recharge in Hebei Plain, North China, to evaluate the impacts of different soil types, land use, irrigation, and crop cultivation practice on recharge. Additional objectives were to evaluate temporal variability of recharge and the effect on results of the particular tracer used. Thirty-nine profiles at representative locations were chosen for investigation. Average recharge rates and recharge coefficient determined by tritium and bromide tracing for different sites were 0.00–1.05 mm/d and 0.0–42.5%, respectively. The results showed relative recharge rates for the following paired influences (items within each pair are listed with...
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This USGS Data Release represents Soil-Water Balance (SWB) groundwater recharge modeling results for the Upper Colorado River Basin (UCRB). The data release was produced in compliance with 'open data' requirements as a way to make the scientific products associated with USGS research efforts and publications available to the public. This dataset comprises SWB model results from runs using projected climate data, summarized by water year, and there are 4 separate datafiles associated with this Data Release: 1. SWB model results for actual evapotranspiration (AET), summarized by water year from 1951 through 2099 2. SWB model results for potential evapotranspiration (PET), summarized by water year from 1951 through...
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This USGS Data Release represents Soil-Water Balance (SWB) groundwater recharge modeling results for the Upper Colorado River Basin (UCRB). The data release was produced in compliance with 'open data' requirements as a way to make the scientific products associated with USGS research efforts and publications available to the public. This dataset comprises SWB model results from runs using historical climate data, and there are 5 separate datafiles associated with this Data Release: 1. SWB model results for actual evapotranspiration (AET), summarized by water year from 1951 through 2010 2. SWB model results for potential evapotranspiration (PET), summarized by water year from 1951 through 2010 3. SWB model results...
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These data are derived from the Basin Characterization Model (BCM) and used as input to a total dissolved solids SPARROW model for the Upper Colorado River Basin. The BCM mechanistically models the pathways of precipitation into evapotranspiration, infiltration into soils, runoff, or percolation below the root zone to recharge groundwater (Flint and others, 2013). The dataset is composed of twelve, 270-meter resolution raster layers representing mean total annual values for water years 1985 - 2012 of actual evapotranspiration (aet), climatic water deficit (cwd), excess water (exc), snowmelt (mlt), snowpack (pck), potential evapotranspiration (pet), precipitation (ppt), recharge (rch), runoff (run), sublimation (sbl),...
    map background search result map search result map UCRB SWB Model Results - Projected Climate Data - Water Years 1951-2099 UCRB SWB Model Results - Observed Climate Data - Water Years 1951-2010 UCRB SWB Model Results - Projected Climate Data - Monthly Results by Sub-Basin Catchment-flowline network and selected model inputs for an enhanced and updated spatially referenced statistical assessment of dissolved-solids load sources and transport in streams of the Upper Colorado River Basin Selected Basin Characterization Model Parameters for the Upper Colorado River Basin UCRB SWB Model Results - Projected Climate Data - Water Years 1951-2099 UCRB SWB Model Results - Observed Climate Data - Water Years 1951-2010 UCRB SWB Model Results - Projected Climate Data - Monthly Results by Sub-Basin Catchment-flowline network and selected model inputs for an enhanced and updated spatially referenced statistical assessment of dissolved-solids load sources and transport in streams of the Upper Colorado River Basin Selected Basin Characterization Model Parameters for the Upper Colorado River Basin