hsg_UCRB_Daymet_resolution.txt is an Esri ASCII grid representing the hydrologic soil group (HSG) for the Upper Colorado River Basin. The HSG for an area is determined by the least water-transmitting layer in the soil column. The Natural Resources Conservation Service (NRCS) classifies four HSGs from Group A (high infiltration capacity and low overland flow potential) to Group D (low infiltration capacity and high overland flow potential). In Soil-Water Balance recharge simulations, a lookup table incorporates HSG and land-cover information for each grid cell to define unique runoff curve numbers, vegetation rooting depths, interception values, and maximum daily recharge values.

nlcd_UCRB_daymet_resolution.txt is an Esri ASCII grid representing land cover information for the Upper Colorado River Basin. The 2011 National Land Cover Database (NLCD) was used to characterize land cover in the UCRB study area.

nlcd_UCRB_daymet_resolution.txt is an Esri ASCII grid representing land cover information for the Upper Colorado River Basin. The 2011 National Land Cover Database (NLCD) was used to characterize land cover in the UCRB study area.

hsg_UCRB_Maurer_resolution.asc is an Esri ASCII grid representing the hydrologic soil group (HSG) for the Upper Colorado River Basin. The HSG for an area is determined by the least water-transmitting layer in the soil column. The Natural Resources Conservation Service (NRCS) classifies four HSGs from Group A (high infiltration capacity and low overland flow potential) to Group D (low infiltration capacity and high overland flow potential). In Soil-Water Balance recharge simulations, a lookup table incorporates HSG and land-cover information for each grid cell to define unique runoff curve numbers, vegetation rooting depths, interception values, and maximum daily recharge values.

hsg_UCRB_Maurer_resolution.asc is an Esri ASCII grid representing the hydrologic soil group (HSG) for the Upper Colorado River Basin. The HSG for an area is determined by the least water-transmitting layer in the soil column. The Natural Resources Conservation Service (NRCS) classifies four HSGs from Group A (high infiltration capacity and low overland flow potential) to Group D (low infiltration capacity and high overland flow potential). In Soil-Water Balance recharge simulations, a lookup table incorporates HSG and land-cover information for each grid cell to define unique runoff curve numbers, vegetation rooting depths, interception values, and maximum daily recharge values.

overland_flow_direction_UCRB_daymet_resolution.txt is an Esri ASCII grid representing overland flow direction in the Upper Colorado River Basin using the D8 flow-routing convention.

overland_flow_direction_UCRB_daymet_resolution.txt is an Esri ASCII grid representing overland flow direction in the Upper Colorado River Basin using the D8 flow-routing convention.

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 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.