Wynn R. Walker

STATE OF THE ART IN HYDRO-CHEMICAL MODELING OF IRRIGATED AGRICULTURE

ABSTRACT A broad based literature review vas undertaken to identify studies that had yielded digital computer models applicable to irrigated agriculture, particularly irrigation return flow (IRF) systems. The programs not listed in technical reports or papers were requested from the various authors. The results of this work are 43 computer models applicable all or in part to the analysis of irrigated agricultre and their quality. A brief evaluation of each model is given. Groundwater models were generally not included. The modeling technology is well developed theoretically but not completely verified due to the large scale of the irrigation system. Most models remain in the research sphere and need to be redefined for the wider utilization of planners. Field data are generally not available to satisfy the input requirements of most models. Accuracies of predictions need to be determined against standardized conditions in order to further model development and parameter sensitivities should be investigated to isolate the most important field data.

MODELING PROCESS FOR ASSESSING WATER QUALITY PROBLEMS AND DEVELOPING APPROPRIATE SOLUTIONS IN IRRIGATED AGRICULTURE

A planning framework is presented for arriving at cost-effective solutions to water pollution problems resulting from subsurface irrigation return flows. The modeling process is demonstrated for salinity management in irrigated agriculture, which involves inflow-outflow analysis, hydro-salinity modeling, soil moisture chemistry simulation, and an optimizational analysis to arrive at the most cost-effective strategy for reducing the salt load in the groundwater reservoir or river.