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Updated estimates of long-term average dissolved-solids loading in streams and rivers of the Upper Colorado River Basin
| Content Provider | Semantic Scholar |
|---|---|
| Author | Tillman, Fred D. Anning, David W. |
| Copyright Year | 2014 |
| Abstract | The Colorado River and its tributaries supply water to more than 35 million people in the United States and 3 million people in Mexico, irrigating over 4.5 million acres of farmland, and annually generating about 12 billion kilowatt hours of hydroelectric power. The Upper Colorado River Basin, part of the Colorado River Basin, encompasses more than 110,000 mi2 and is the source of much of more than 9 million tons of dissolved solids that annually flows past the Hoover Dam. High dissolved-solids concentrations in the river are the cause of substantial economic damages to users, primarily in reduced agricultural crop yields and corrosion, with damages estimated to be greater than 300 million dollars annually. In 1974, the Colorado River Basin Salinity Control Act created the Colorado River Basin Salinity Control Program to investigate and implement a broad range of salinity control measures. A 2009 study by the U.S. Geological Survey, supported by the Salinity Control Program, used the Spatially Referenced Regressions on Watershed Attributes surface-water quality model to examine dissolved-solids supply and transport within the Upper Colorado River Basin. Dissolved-solids loads developed for 218 monitoring sites were used to calibrate the 2009 Upper Colorado River Basin Spatially Referenced Regressions on Watershed Attributes dissolved-solids model. This study updates and develops new dissolved-solids loading estimates for 323 Upper Colorado River Basin monitoring sites using streamflow and dissolved-solids concentration data through 2012, to support a planned Spatially Referenced Regressions on Watershed Attributes modeling effort that will investigate the contributions to dissolved-solids loads from irrigation and rangeland practices. Introduction More than 3 million people in Mexico and 35 million people in the United States depend on the Colorado River to supply their domestic and industrial water needs (Bureau of Reclamation, 2011; Colorado River Basin Salinity Control Forum, 2013). The Colorado River also supplies irrigation water for over 4.5 million acres of land in the United States and Mexico and hydroelectric power along the river and its tributaries generates about 12 billion kilowatt hours annually (Colorado River Basin Salinity Control Forum, 2011). From headwaters in the Rocky Mountains through seven states and Mexico, the Colorado River traverses more than 1,400 mi to discharge into the Gulf of California (fig. 1A). Dissolved-solids concentrations in the river increase from about 50 mg/L at the river headwaters to about 500 mg/L at Lees Ferry, Arizona to about 850 mg/L where it crosses the United States border with Mexico (Anning and others, 2007). More than 9 million tons of dissolved solids annually flow past Hoover Dam (Anning and others, 2007). The origin of Colorado River salinity is primarily geologic material that was deposited from ancient inland seas and waterways (Colorado River Basin Salinity Control Forum, 2013), and 55–60 percent of the salinity in the river system is from natural sources—primarily saline spring discharge and erosion of saline geologic formations (Kenney and others, 2009). Dissolvedsolids concentrations also can increase through human activities that increase loading (primarily irrigation, but also municipal and industrial development, as well as mining and drilling operations) and through accumulation (evaporation from reservoir operations). The Bureau of Reclamation estimates that high salinity Colorado River water causes damages of more than 300 million dollars per year to users in the United States (Colorado River Basin Salinity Control Forum, 2013), primarily owing to reduced agricultural crop yields, corrosion, and plugging of pipes and water fixtures in housing and industry (Bureau of Reclamation, 2011). In 2009, a U.S. Geological Survey (USGS) investigation of Upper Colorado River Basin (UCRB) dissolved-solids sources and transport used the Spatially Referenced Regressions on Watershed Attributes (SPARROW) surface-water quality model to relate dissolved-solids loads to upland catchment attributes (Kenney and others, 2009). The 2009 UCRB SPARROW model focused on geologic and agricultural sources of dissolved solids in the basin and was calibrated to dissolved-solids loads from 218 water-quality monitoring sites estimated by Anning and others (2007). A new UCRB SPARROW model is planned that will further investigate dissolved-solids sources and transport in the basin by incorporating geospatial information on irrigation practices and contributions from rangelands, among other improvements. Updated dissolved-solids loadings for UCRB 2 Updated Estimates of Long-Term Average Dissolved-Solids Loading in Streams and Rivers of the Upper Colorado River Basin monitoring sites were developed to provide the revised SPARROW model with updated calibration data. Purpose and Scope This report documents the data and methods used to estimate long-term mean annual dissolved-solids loading at water-quality sites on UCRB streams and rivers. Existing streamflow and dissolved-solids concentration data from the USGS National Water Information System (NWIS) were used in the development of these estimates. Where sufficient data were available as described in this report, dissolvedsolids load estimates were detrended to water year 2010. The UCRB boundary used in this study is the watershed delineated by USGS hydrologic unit code 14 (HUC14), established as part of the USGS hydrologic unit system (Seaber and others, 1987). Description of Study Area The Colorado River Basin drains parts of Wyoming, Utah, Colorado, New Mexico, Arizona, Nevada, California, and Mexico, and is divided into upper and lower basins at the compact point of Lee Ferry, Arizona, a location 1 mi downstream of the mouth of the Paria River (fig. 1A, 1B; Anderson, 2004). The UCRB is defined for this study as the 113,406 mi2 drainage area (HUC14) upstream of USGS streamflow-gaging station 09380000, Colorado River at Lees Ferry, Arizona (fig. 1B). Major tributaries to the Colorado River in the Upper Basin include the Dolores, Green, Gunnison, San Juan, White, and Yampa Rivers (fig. 1B). Average annual precipitation ranges from less than 10 in. in low elevation areas to more than 39 in. in high elevation areas in the Southern Rocky Mountains (fig. 1C, PRISM Climate Group, Oregon State University, 2012). UCRB land cover is predominately shrub/scrub and evergreen forest (Fry and others, 2011), with few high-density population centers (fig. 1D). Major dissolved constituents in UCRB streams and rivers are the cations calcium, magnesium, sodium, and potassium; and the anions sulfate, chloride, and bicarbonate; and neutral silica (Liebermann and others, 1989). Important geologic sources of dissolved solids in the UCRB include the Upper Cretaceous Mancos Shale, the Paradox Member of the Pennsylvanian Hermosa Formation, and the Eocene Green River Formation (Liebermann and others, 1989). Factors that are related to the transport of salinity to UCRB streams and rivers include the amount of precipitation, soil type and thickness, and land-surface elevation (Kenney and others, 2009). Methods Models of dissolved-solids concentrations were calibrated with streamflow and water-quality data by the Fluxmaster program that uses batch-processing methods in the SAS® statistical software to estimate flow and water-quality models across multiple stations (Schwarz and others, 2006). For each of three dissolved-solids parameters (described in section, “Data”), six models were considered for each site that included varying combinations of flow, time (trend), and seasonality. The best option was selected from the six models for each dissolved-solids parameter at each site, followed by selection of the best dissolved-solids model from the three dissolved-solids parameters. Concentration and load results were compared with published estimates from Anning and Flynn (2014). Data Dissolved-solids concentration and daily streamflow data from NWIS (http://waterdata.usgs.gov/nwis) for UCRB study area sites were used to calibrate the dissolved-solids models. Data for different measures of dissolved solids, including specific conductance (SC; p00095), residue on evaporation at 180 °C (ROE; p70300), and sum of the dissolved constituents (SUM; p70301), were compiled from NWIS. Dissolved-solids concentration data for more than 210,000 observations from 710 sites in the UCRB constituted the base water-quality dataset for the study. The period of record for data used in calibrating dissolved-solids flux estimates was from October 1, 1984 to September 30, 2012. The selected period of record was a balance of the necessity of having sufficient data with which to calibrate models with the desire to represent recent conditions in the study area. A search for outliers and quality issues in the dissolved-solids data was performed first by visually inspecting plots of data for all sites. Data that appeared to have quality issues (for example, a decimal place error), were low or high values relative to nearby points, or were few in number and distant in time (most more than 7 years) from other data were removed from the dataset. A second investigation of the dissolved-solids data was performed by computing ratios of the different dissolved-solids parameters (p70300/p00095, p70301/ p00095, and p70301/p70300) for times when multiple parameter data were available and removing observations that caused anomalously high or low ratios. The outlier search identified 49 observations that were removed from the nearly 80,000 available for the period of interest. Development and Evaluation of DissolvedSolids Models The Fluxmaster program (Schwarz and others, 2006) was used to estimate mean annual loads of dissolved solids at UCRB sites. Fluxmaster estimates log-transformed dissolved-solids concentrations from log-transformed mean daily streamflow and other explanatory variables (desc |
| File Format | PDF HTM / HTML |
| DOI | 10.3133/ofr20141148 |
| Alternate Webpage(s) | https://pubs.usgs.gov/of/2014/1148/pdf/ofr2014-1148.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
