Spatial Modeling of Water Use in California Rice Production

Abstract

There are growing concerns over the water use efficiencies in California rice production. To address these concerns it is necessary to better understand the balance of flows within the system. A spatial water-balance model was developed, using a geographic information system (GIS), to estimate the inflows to and outflows from the Glenn-Colusa Irrigation District in California's Sacramento Valley. System inflows included precipitation and irrigation. Outflows included evapotranspiration, surface runoff, and percolation. The storage capacity of the system was also estimated. The model was run to simulate twenty-four months from January 2003 through December 2004. The model was assessed by determining if the equation was balanced. Throughout the study the model remained balanced within the system's maximum storage capacity. The results suggest that even with limited data, spatial water-balance models provide useful descriptions of regional agricultural water use.