... In addition, an accessible version of Acrobat Reader 5.0 for Windows (English only), which co... more ... In addition, an accessible version of Acrobat Reader 5.0 for Windows (English only), which contains support for screen readers, is available. These tools and the accessiblereader may be obtained free from Adobe at Adobe Access. ...
The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program conducts rese... more The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program conducts research to provide an understanding of the water-quality conditions in more than 50 major river basins and aquifer systems across the country that constitute a significant part of the Nation's water supply and are representative of the Na- tion's major hydrologic landscapes, priority ecoregions, and agricultural, urban, and natural sources of contamination. Recent NAWQA investigations for a study area in central Arizona have shown the effects of natural and human fac- tors on stream water quality. Results from these studies are summarized below and are fully documented in the reports listed in the section entitled "For more information." Highly Contrasted Hydrologic Provinces The Central Highlands and Basin and Range Lowlands are two fundamentally different hydrologic provinces in central Arizona (fig. 1). In the Basin and Range Lowlands, basins are greater in areal exte...
JAWRA Journal of the American Water Resources Association, 2011
Information on important source areas for dissolved solids in streams of the southwestern United ... more Information on important source areas for dissolved solids in streams of the southwestern United States, the relative share of deliveries of dissolved solids to streams from natural and human sources, and the potential for salt accumulation in soil or groundwater was developed using a SPAtially Referenced Regressions On Watershed attributes model. Predicted area-normalized reach-catchment delivery rates of dissolved solids to streams ranged from <10 (kg/year)/km(2) for catchments with little or no natural or human-related solute sources in them to 563,000 (kg/year)/km(2) for catchments that were almost entirely cultivated land. For the region as a whole, geologic units contributed 44% of the dissolved-solids deliveries to streams and the remaining 56% of the deliveries came from the release of solutes through irrigation of cultivated and pasture lands, which comprise only 2.5% of the land area. Dissolved-solids accumulation is manifested as precipitated salts in the soil or underlying sediments, and (or) dissolved salts in soil-pore or sediment-pore water, or groundwater, and therefore represents a potential for aquifer contamination. Accumulation rates were <10,000 (kg/year)/km(2) for many hydrologic accounting units (large river basins), but were more than 40,000 (kg/year)/km(2) for the Middle Gila, Lower Gila-Agua Fria, Lower Gila, Lower Bear, Great Salt Lake accounting units, and 247,000 (kg/year)/km(2) for the Salton Sea accounting unit.
Geospatial Data to Support Analysis of Water-Quality Conditions in Basin-Fill Aquifers in the Sou... more Geospatial Data to Support Analysis of Water-Quality Conditions in Basin-Fill Aquifers in the Southwestern United States.
... In addition, an accessible version of Acrobat Reader 5.0 for Windows (English only), which co... more ... In addition, an accessible version of Acrobat Reader 5.0 for Windows (English only), which contains support for screen readers, is available. These tools and the accessiblereader may be obtained free from Adobe at Adobe Access. ...
The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program conducts rese... more The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program conducts research to provide an understanding of the water-quality conditions in more than 50 major river basins and aquifer systems across the country that constitute a significant part of the Nation's water supply and are representative of the Na- tion's major hydrologic landscapes, priority ecoregions, and agricultural, urban, and natural sources of contamination. Recent NAWQA investigations for a study area in central Arizona have shown the effects of natural and human fac- tors on stream water quality. Results from these studies are summarized below and are fully documented in the reports listed in the section entitled "For more information." Highly Contrasted Hydrologic Provinces The Central Highlands and Basin and Range Lowlands are two fundamentally different hydrologic provinces in central Arizona (fig. 1). In the Basin and Range Lowlands, basins are greater in areal exte...
JAWRA Journal of the American Water Resources Association, 2011
Information on important source areas for dissolved solids in streams of the southwestern United ... more Information on important source areas for dissolved solids in streams of the southwestern United States, the relative share of deliveries of dissolved solids to streams from natural and human sources, and the potential for salt accumulation in soil or groundwater was developed using a SPAtially Referenced Regressions On Watershed attributes model. Predicted area-normalized reach-catchment delivery rates of dissolved solids to streams ranged from <10 (kg/year)/km(2) for catchments with little or no natural or human-related solute sources in them to 563,000 (kg/year)/km(2) for catchments that were almost entirely cultivated land. For the region as a whole, geologic units contributed 44% of the dissolved-solids deliveries to streams and the remaining 56% of the deliveries came from the release of solutes through irrigation of cultivated and pasture lands, which comprise only 2.5% of the land area. Dissolved-solids accumulation is manifested as precipitated salts in the soil or underlying sediments, and (or) dissolved salts in soil-pore or sediment-pore water, or groundwater, and therefore represents a potential for aquifer contamination. Accumulation rates were <10,000 (kg/year)/km(2) for many hydrologic accounting units (large river basins), but were more than 40,000 (kg/year)/km(2) for the Middle Gila, Lower Gila-Agua Fria, Lower Gila, Lower Bear, Great Salt Lake accounting units, and 247,000 (kg/year)/km(2) for the Salton Sea accounting unit.
Geospatial Data to Support Analysis of Water-Quality Conditions in Basin-Fill Aquifers in the Sou... more Geospatial Data to Support Analysis of Water-Quality Conditions in Basin-Fill Aquifers in the Southwestern United States.
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