PARAMETRIZATION OF TOTAL AVAILABLE WATER FOR STATEWIDE WATER ASSESSMENT IN NEW MEXICO

To accurately estimate groundwater recharge at the landscape scale, it is necessary to predict the amount of water stored in soils within the root zone where water is subject to evaporation, transpiration, and/or deep percolation (recharge). Root zones in soil and weathered bedrock serve as leaky reservoirs that store rain water and snow melt. The amount of water held within the root zone is termed total available water (TAW). TAW is a critical parameter in operational hydrologic, weather and land data assimilation systems that use a water balance approach for assessment of a wide range of hydro-meteorological phenomena, including but not limited to, evapotranspiration, runoff and groundwater recharge. This paper presents a proof-of-concept approach to determine the TAW of a soil using remote sensing of soil moisture and a distributed hydrological model. The surface energy balance algorithm for land (SEBAL) is used to produce “observed” soil moisture images from thermal Landsat imagery. The soil moisture observations are compared with the results of a distributed hydrological model, the evaporation, transpiration and recharge model (ETRM). The TAW of the soil in the ETRM model is adjusted until a good agreement between the ETRM and the observed soil moisture is reached. This approach will allow for TAW to be parametrized for the entire state of New Mexico, which will assist in researchers’ efforts to quantify distributed hydrological recharge of groundwater. We present our proof of concept for an area of interest in the state of New Mexico.