REGIONAL IRRIGATION WATER DEMAND

The study of irrigation water demand has generally been focused at the field level, and the question can be raised as to whether field-level estimates can be applied successfully to predict the water usage of a region. In this case study, crop and water-use data for a 30-year time period were analyzed for a 200,000 ha desert region in southern California, the Imperial Irrigation District, which relies exclusively on Colorado River water. Attempts to correlate water usage with crop acreage and climatic variables were made using the Blaney-Criddle evapotranspiration method, but showed limited success. It is unknown whether the use of more sophisticated estimation techniques, which would require a larger data set than was available for the present study, would yield better results.