Simulation and Evaluation on the Effect of Drainage Water Reusein the Lower Reaches of the Yellow River

Based on on-farm observations and experiments, SWAP Model was used to analyze the seasonal variation of soil salt and impact of groundwater table on the distribution of soil salt under conditions of drainage water reuse in Bojili Irrigation District in the lower reaches of the Yellow River, and simulate the effect of supplementary irrigation by surface drainage water on crop's yield. It's indicated from the study that soil salt accumulation caused from saline drained-water irrigation occurs mainly in the growth period of winter wheat, not serious in the growth period of summer maize. The efficient control of groundwater table would simultaneously help to reduce the salt accumulated in the soil profile and thus help in maintenance of salt balance within root zone. The reuse of drainage water with salt content up to 4 mg/cm~3 for irrigate in winter wheat during later stage results in yield improvements over deficit irrigation without affecting the subsequent summer maize yields. The reuse of drainage water, thus offers opportunities for improving irrigation water management in winter wheat for the irrigation districts in the lower reaches of the Yellow River facing water shortage.