Colorado River Near Real-Time TWS Dynamics: Application of the SAHRA Geodatabase

The total amount of terrestrial water stored in a river basin is an important state variable that affects stream flow at various timescales and defines the river basins response to climatic conditions. An accurate estimation of the terrestrial water storage (TWS) variability in the basin could improve the seasonal and annual prediction of water availability in the basin. A near real-time monitoring system that traces TWS changes in the and its subbasins was developed and is now available for use in further research or by water managers (http://voda.hwr.arizona.edu/twsc/sahra/). The system is based on the following automated procedures: (1) downloading forcing, remotely sensed and in-situ data; (2) running a series of models to produce estimates of TWS changes; (3) storing downloaded and model generated data in the SAHRA’s Geodatabase or file systems; and (4) analyzing data and generating outputs in bi-weekly time intervals.

Direct determination of TWS is difficult due to insufficient in-situ data on space-time variability of hydrologic stores (snow, soil moisture, and groundwater) and fluxes (precipitation, evapotranspiration). However, the following alternative methods: (1) the Basin-Scale Water Balance (BSWB) using North American Regional Reanalysis (NARR) dataset; (2) the Variable Infiltration Capacity (VIC) forced with gridded meteorological data; and (3) new remotely sensed gravity field data from the Gravity Recovery and Climate Experiment (GRACE) show great potential to improve the estimation of TWS variability.