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 more than 4.5 million acres of farmland, and generating about 12 billion kilowatt hours of hydroelectric power annually. Planning for the sustainable management of the Colorado River in future climates requires an understanding of the Upper Colorado River Basin groundwater system. The Upper Colorado River Basin, encompassing more than 110,000 square miles (mi2), contains the headwaters of the Colorado River and is an important source of snowmelt runoff to the River. Groundwater discharge also is an important source of water in the River and its tributaries, with estimates ranging from 21 to 58 percent of streamflow in the upper basin. A study by Castle and others (2014) using remotely sensed gravity observations from the NASA Gravity Recovery and Climate Experiment (GRACE) mission found that UCRB groundwater was depleted by more than 17 million acre-feet (ft) from December 2004 to November 2013. Understanding groundwater-budget components, including groundwater recharge, is important to sustainably manage both groundwater and surface-water supplies in the Colorado River Basin.

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.

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. There are 4 separate datasets associated with this Data Release: 1. SWB model results from simulations run using observed climate data, summarized by water year from 1951 through 2010 2. SWB model results from simulations run using projected climate data, summarized by month and UCRB sub-basin from 1950 through 2099 3. SWB model results from simulations run using projected climate data, summarized by water year from 1951 through 2099 4. SWB model results from simulations run on climate data from 1981 through 2014 at ~800m, ~4km, and ~12km spatial scales.

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. There are 4 separate datasets associated with this Data Release: 1. SWB model results from simulations run using observed climate data, summarized by water year from 1951 through 2010 2. SWB model results from simulations run using projected climate data, summarized by month and UCRB sub-basin from 1950 through 2099 3. SWB model results from simulations run using projected climate data, summarized by water year from 1951 through 2099 4. SWB model results from simulations run on climate data from 1981 through 2014 at ~800m, ~4km, and ~12km spatial scales.

The Colorado River and its tributaries supply water to more than 35 million people in the United States and 3 million people in Mexico (Bureau of Reclamation, 2011), irrigating more than 4.5 million acres of farmland, and generating about 12 billion kilowatt hours of hydroelectric power annually (Colorado River Basin Salinity Control Forum, 2011). Planning for the sustainable management of the Colorado River in future climates requires an understanding of the Lower Colorado River Basin groundwater system. This data release contains summarized output from Soil-Water Balance groundwater infiltration model simulations for the Lower Colorado River Basin. Model output available in this release includes groundwater infiltration, potential evapotranspiration (PET), actual evapotranspiration (AET), precipitation, and temperature.

The Colorado River and its tributaries supply water to more than 35 million people in the United States and 3 million people in Mexico (Bureau of Reclamation, 2011), irrigating more than 4.5 million acres of farmland, and generating about 12 billion kilowatt hours of hydroelectric power annually (Colorado River Basin Salinity Control Forum, 2011). Planning for the sustainable management of the Colorado River in future climates requires an understanding of the Lower Colorado River Basin groundwater system. This data release contains summarized output from Soil-Water Balance groundwater infiltration model simulations for the Lower Colorado River Basin. Model output available in this release includes groundwater infiltration, potential evapotranspiration (PET), actual evapotranspiration (AET), precipitation, and temperature.

awc_UCRB_Daymet_resolution.txt is an Esri ASCII grid representing the available water capacity (AWC) for the Upper Colorado River Basin. AWC (available water capacity) is the amount of water that a soil can hold, and is between a soil’s field capacity and the wilting point. In Soil-Water Balance (SWB) model recharge simulations, AWC is multiplied by root zone depth to define the maximum water capacity of a cell, and any soil-moisture exceeding this amount is converted to recharge.

awc_UCRB_Daymet_resolution.txt is an Esri ASCII grid representing the available water capacity (AWC) for the Upper Colorado River Basin. AWC (available water capacity) is the amount of water that a soil can hold, and is between a soil’s field capacity and the wilting point. In Soil-Water Balance (SWB) model recharge simulations, AWC is multiplied by root zone depth to define the maximum water capacity of a cell, and any soil-moisture exceeding this amount is converted to recharge.

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