This data release contains two sets of estimated values at selected sites within the Colorado River Basin: 1) daily specific conductance at 143 sites in the Upper Basin and 3 sites in the Lower Basin (WY 1980-2022); and 2) daily baseflow discharge at 100 sites in the Upper Basin and 3 sites in the Lower Basin (WY 1980-2022). The estimates of daily baseflow discharge will be used as input to an application of the USGS GSFLOW model, which is a coupled groundwater and surface-water flow model based on the integration of the USGS Precipitation-Runoff Modeling System (PRMS-V) and the USGS Modular Groundwater Flow Model (MODFLOW).

This data release contains two sets of estimated values at selected sites within the Colorado River Basin: 1) daily specific conductance at 143 sites in the Upper Basin and 3 sites in the Lower Basin (WY 1980-2022); and 2) daily baseflow discharge at 100 sites in the Upper Basin and 3 sites in the Lower Basin (WY 1980-2022). The estimates of daily baseflow discharge will be used as input to an application of the USGS GSFLOW model, which is a coupled groundwater and surface-water flow model based on the integration of the USGS Precipitation-Runoff Modeling System (PRMS-V) and the USGS Modular Groundwater Flow Model (MODFLOW).

This data release contains measured stream discharge and total dissolved solids (TDS) data and estimated values for daily stream TDS loads, daily baseflow discharge, and daily baseflow TDS loads for 205 locations in the Upper Colorado River Basin. The estimated values, which represent conditions between 10/1/1985 and 9/30/2020, were obtained using the Weighted Regressions on Time, Discharge, and Season (WRTDS) program and a previously published method for hydrograph separation.

This data release contains measured stream discharge and total dissolved solids (TDS) data and estimated values for daily stream TDS loads, daily baseflow discharge, and daily baseflow TDS loads for 205 locations in the Upper Colorado River Basin. The estimated values, which represent conditions between 10/1/1985 and 9/30/2020, were obtained using the Weighted Regressions on Time, Discharge, and Season (WRTDS) program and a previously published method for hydrograph separation.

The U.S. Geological Survey (USGS) as part of the Department of Interior WaterSmart Program compiled published estimates of groundwater discharge to streams in the Upper Colorado River Basin into a dataset and developed a geospatial database. For the purpose of this compilation, groundwater discharge to streams consists of base-flow, and may include contributions from groundwater discharge from various flow paths, lateral seepage, hyporheic flow, and irrigation return flow. Stream reaches from the National Hydrography Dataset (NHD) where there was groundwater discharge estimates were delineated in the geospatial database. Attributes describing the methods used for estimating groundwater discharge were created. Feature class attributes associated with each stream reach include: groundwater discharge (acre-ft/yr), method of measurement, report reference, defined reach, base flow index estimate (acre-ft/yr), and 8-digit HUC(s) (hydrologic unit code(s) for the reach). In addition, groundwater discharge estimates were calculated using attributes from a flow characteristics dataset (Wolock, 2003), the average annual base-flow index (BFI) value and the average daily streamflow value. The calculated groundwater discharge estimates were included in the database as separate attributes and were compared to reported estimates of groundwater discharge. Groundwater discharge estimates calculated using BFI were greater than reported groundwater discharge estimates. References cited: Wolock, D., 2003, Flow Characteristics at U.S. Geological Survey Streamgages in the Conterminous United States: U.S. Geological Survey Open-File Report 2003-146, accessed July 2, 2012 at https://water.usgs.gov/GIS/metadata/usgswrd/XML/qsitesdd.xml

The U.S. Geological Survey (USGS) as part of the Department of Interior WaterSmart Program compiled published estimates of groundwater discharge to streams in the Upper Colorado River Basin into a dataset and developed a geospatial database. For the purpose of this compilation, groundwater discharge to streams consists of base-flow, and may include contributions from groundwater discharge from various flow paths, lateral seepage, hyporheic flow, and irrigation return flow. Stream reaches from the National Hydrography Dataset (NHD) where there was groundwater discharge estimates were delineated in the geospatial database. Attributes describing the methods used for estimating groundwater discharge were created. Feature class attributes associated with each stream reach include: groundwater discharge (acre-ft/yr), method of measurement, report reference, defined reach, base flow index estimate (acre-ft/yr), and 8-digit HUC(s) (hydrologic unit code(s) for the reach). In addition, groundwater discharge estimates were calculated using attributes from a flow characteristics dataset (Wolock, 2003), the average annual base-flow index (BFI) value and the average daily streamflow value. The calculated groundwater discharge estimates were included in the database as separate attributes and were compared to reported estimates of groundwater discharge. Groundwater discharge estimates calculated using BFI were greater than reported groundwater discharge estimates. References cited: Wolock, D., 2003, Flow Characteristics at U.S. Geological Survey Streamgages in the Conterminous United States: U.S. Geological Survey Open-File Report 2003-146, accessed July 2, 2012 at https://water.usgs.gov/GIS/metadata/usgswrd/XML/qsitesdd.xml

Understanding how changing climatic conditions affect streamflow volume and timing is critical for effective water management. In the Rio Grande Basin of the southwest U.S., decreasing snowpack, increasing minimum temperatures, and decreasing streamflow have been observed in recent decades, but the effects of hydroclimatic changes on baseflow, or groundwater discharge to streams, have not been investigated. The dataset created in this data release was used to help support a study to determine how trends in precipitation, snowpack accumulation, and snowmelt rate relate to streamflow, baseflow, and the hydrologic partitioning of baseflow and runoff at 12 sites in the Upper Rio Grande Basin (URGB) during 1980 to 2015. Streamflow was partitioned into baseflow and runoff components at a daily time step using conductivity mass balance hydrograph separation. Trends in annual streamflow, baseflow, runoff, baseflow index, precipitation, snowmelt rate, and peak snow water equivalent (SWE) were evaluated from 1980 to 2015 using the non-parametric Mann-Kendall trend test.

Understanding how changing climatic conditions affect streamflow volume and timing is critical for effective water management. In the Rio Grande Basin of the southwest U.S., decreasing snowpack, increasing minimum temperatures, and decreasing streamflow have been observed in recent decades, but the effects of hydroclimatic changes on baseflow, or groundwater discharge to streams, have not been investigated. The dataset created in this data release was used to help support a study to determine how trends in precipitation, snowpack accumulation, and snowmelt rate relate to streamflow, baseflow, and the hydrologic partitioning of baseflow and runoff at 12 sites in the Upper Rio Grande Basin (URGB) during 1980 to 2015. Streamflow was partitioned into baseflow and runoff components at a daily time step using conductivity mass balance hydrograph separation. Trends in annual streamflow, baseflow, runoff, baseflow index, precipitation, snowmelt rate, and peak snow water equivalent (SWE) were evaluated from 1980 to 2015 using the non-parametric Mann-Kendall trend test.

This USGS Data Release represents Soil-Water Balance (SWB) groundwater infiltration modeling results for the Lower Colorado River Basin (LCRB). The data release was produced in compliance with 'open data' requirements as a way to make the scientific data associated with USGS research efforts and publications available to the public. There are 3 separate groups of datasets associated with this Data Release: 1. SWB model results from simulations run using projected climate data, summarized by month from 1950 through 2099, for the LCRB within the United States 2. SWB model results from simulations run using projected climate data, summarized by month from 1950 through 2099, for the Grand Canyon region 3. SWB model results from simulations run using projected climate data, summarized by month from 1950 through 2099, for the alluvial basins of Arizona.

This USGS Data Release represents Soil-Water Balance (SWB) groundwater infiltration modeling results for the Lower Colorado River Basin (LCRB). The data release was produced in compliance with 'open data' requirements as a way to make the scientific data associated with USGS research efforts and publications available to the public. There are 3 separate groups of datasets associated with this Data Release: 1. SWB model results from simulations run using projected climate data, summarized by month from 1950 through 2099, for the LCRB within the United States 2. SWB model results from simulations run using projected climate data, summarized by month from 1950 through 2099, for the Grand Canyon region 3. SWB model results from simulations run using projected climate data, summarized by month from 1950 through 2099, for the alluvial basins of Arizona.