Geology topics

Susan G. Buto

Publications and source records attributed to Susan G. Buto.

22 records · Page 2Linked to original sources

USGS2009

Spatially referenced statistical assessment of dissolved-solids load sources and transport in streams of the Upper Colorado River Basin

The Upper Colorado River Basin (UCRB) discharges more than 6 million tons of dissolved solids annually, about 40 to 45 percent of which are attributed to agricultural activities. The U.S. Department of the Interior estimates economic damages related to salinity in excess of $330 million annually in the Colorado River Basin. Salinity in the UCRB, as measured by dissolved-solids load and concentration, has been studied extensively during the past century. Over this period, a solid conceptual understanding of the sources and transport mechanisms of dissolved solids in the basin has been developed. This conceptual understanding was incorporated into the U.S. Geological Survey Spatially Referenced Regressions on Watershed Attributes (SPARROW) surface-water quality model to examine statistically the dissolved-solids supply and transport within the UCRB. Geologic and agricultural sources of dissolved solids in the UCRB were defined and represented in the model. On the basis of climatic and hydrologic conditions along with data availability, water year 1991 was selected for examination with SPARROW. Dissolved-solids loads for 218 monitoring sites were used to calibrate a dissolved-solids SPARROW model for the UCRB. The calibrated model generally captures the transport mechanisms that deliver dissolved solids to streams of the UCRB as evidenced by R2 and yield R2 values of 0.98 and 0.71, respectively. Model prediction error is approximated at 51 percent. Model results indicate that of the seven geologic source groups, the high-yield sedimentary Mesozoic rocks have the largest yield of dissolved solids, about 41.9 tons per square mile (tons/mi2). Irrigated sedimentary-clastic Mesozoic lands have an estimated yield of 1,180 tons/mi2, and irrigated sedimentary-clastic Tertiary lands have an estimated yield of 662 tons/mi2. Coefficients estimated for the seven landscape transport characteristics seem to agree well with the conceptual understanding of the role they play in the delivery of dissolved solids to streams in the UCRB. Predictions of dissolved-solids loads were generated for more than 10,000 stream reaches of the stream network defined in the UCRB. From these estimates, the downstream accumulation of dissolved solids, including natural and agricultural components, were examined in selected rivers. Contributions from each of the 11 dissolved-solids sources were also examined at select locations in the Grand, Green, and San Juan Divisions of the UCRB. At the downstream boundary of the UCRB, the Colorado River at Lees Ferry, Arizona, monitoring site, the dissolved-solids contribution of irrigated agricultural lands and natural sources were about 45 and 57 percent, respectively. Finally, model predictions, including the contributions of natural and agricultural sources for selected locations in the UCRB, were compared with results from two previous studies.

Arizona, Colorado, Idaho, New Mexico, Utah, Wyomin↗

USGS2008

Flood plain delineation for the Fremont River and Bull Creek, Hanksville, Utah

Predicted inundation maps for the Fremont River and Bull Creek in Hanksville, Utah, were developed using one-dimensional hydraulic models. Estimates of the 1-percent chance (100-year) peak streamflows were determined for the Fremont River and Bull Creek study reaches by using annual peak series data from streamflow-gaging stations and regional peak-flow regression equations. Surveyed topographic data for the study reaches were processed for use in the one-dimensional hydraulic models. The 1-percent chance (100-year) peak streamflows were simulated with hydraulic models to obtain predicted water-surface elevations. Water-surface elevations were then used to map the predicted inundation on a recent aerial photograph. The 1-percent chance (100-year) flood plain for the Fremont River in Hanksville, Utah, included some agricultural lands and did not encroach upon the town. The 1-percent chance (100-year) flood plain on the west side of Bull Creek was found to include a large portion of the town of Hanksville, Utah.

Utah↗

USGS2007

Geospatial database of ground-water altitude and depth-to-ground-water data for Utah, 1971-2000

A geospatial database of ground-water-level altitude and depth-to-ground-water data for Utah was developed. Water-level contours from selected published reports were converted to digital Geographic Information System format and attributes describing the contours were added. Water-level altitude values were input to an inverse distance weighted interpolator to create a raster of interpolated water-level altitude for each report. The water-level altitude raster was subtracted from digital land-surface altitude data to obtain depth-to-water rasters for each study. Comparison of the interpolated rasters to actual water-level measurements shows that the interpolated water-level altitudes are well correlated with measured water-level altitudes from the same time period. The data can be downloaded and displayed in any Geographic Information System or can be explored by downloading a data package and map from the U.S. Geological Survey.

Utah↗

USGS2006

Water-Table Levels and Gradients, Nevada, 1947-2004

In 1999, the U.S. Environmental Protection Agency began a program to protect the quality of ground water in areas other than ground-water protection areas. These other sensitive ground water areas (OSGWA) are areas that are not currently, but could eventually be, used as a source of drinking water. The OSGWA program specifically addresses existing wells that are used for underground injection of motor-vehicle waste. To help determine whether a well is in an OSGWA, the Nevada Division of Environmental Protection needs statewide information on depth to water and the water table, which partly control the susceptibility of ground water to contamination and contaminant transport. This report describes a study that used available maps and data to create statewide maps of water-table and depth-to-water contours and surfaces, assessed temporal changes in water-table levels, and characterized water-table gradients in selected areas of Nevada. A literature search of published water-table and depth-to-water contours produced maps of varying detail and scope in 104 reports published from 1948 to 2004. Where multiple maps covered the same area, criteria were used to select the most recent, detailed maps that covered the largest area and had plotted control points. These selection criteria resulted in water-table and depth-to-water contours that are based on data collected from 1947 to 2004 being selected from 39 reports. If not already available digitally, contours and control points were digitized from selected maps, entered into a geographic information system, and combined to make a statewide map of water-table contours. Water-table surfaces were made by using inverse distance weighting to estimate the water table between contours and then gridding the estimates. Depth-to-water surfaces were made by subtracting the water-table altitude from the land-surface altitude. Water-table and depth-to-water surfaces were made for only 21 percent of Nevada because of a lack of information for 49 of 232 basins and for most consolidated-rock hydrogeologic units. Depth to water is commonly less than 50 feet beneath valley floors, 50 to 500 feet beneath alluvial fans, and more than 500 feet in some areas such as north-central and southern Nevada. In areas without water-table information, greasewood and mapped ground-water discharge areas are good indicators of depth to water less than 100 feet. The average difference between measured depth to water and depth to water estimated from surfaces was 90 feet. More recent and detailed information may be needed than that presented in this report to evaluate a specific site. Temporal changes in water-table levels were evaluated for 1,981 wells with 10 or more years between the first depth-to-water measurement and last measurement made since 1990. The greatest increases in depth to water occurred where the first measurement was less than 200 feet, where the time between first and last measurements was 40 years or less, and for wells between 100 and 600 feet deep. These characteristics describe production wells where ground water is fairly shallow in recently developing areas such as the Las Vegas and Reno metropolitan areas. In basins with little pumping, 90 percent of the changes during the past 100 years are within ?20 feet, which is about the natural variation in the water table due to changes in the climate and recharge. Gradients in unconsolidated sediments of the Great Basin are generally steep near mountain fronts, shallow beneath valley floors, and depend on variables such as the horizontal hydraulic conductivity of adjacent consolidated rocks and recharge. Gradients beneath alluvial fans and valley floors at 58 sites were correlated with selected variables to identify those variables that are statistically related. Water-table measurements at three sites were used to characterize the water table between the valley floor and consolidated rock. Water-table gradients beneath alluvial fan

Scientific Investigations Report↗