IRRIGATION WATER MANAGEMENT STUDIES FOR RICE BY COMPUTER SIMULATION

Abstract

A computer simulation model developed using the concept of rotation irrigation was used to estimate the optimal Irrigation time Interval, determine the effects of subdividing the irrigable area into rotation areas on the yield of rice, estimate the maximum area that would give the highest yield and the optimal area that could be put under rice production for a river water source. The model was run using a 25-year data on rainfall, pan evaporation and stream flow. Results indicated that subdividing the irrigable area into rotation areas was not necessary when water supply was adequate. Rotation interval of 1 to 8 days did not significantly affect the yield of rice; however, an interval of more than 8 days considerably decreased the yield. For the irrigable area to be optimal, It was necessary to divide the area into 4 rotation areas which were irrigated at 4-day intervals. There was no significant difference between rotation Irrigation and continuous irrigation schemes for small irrigable areas when water supply was adequate. However, rotation Irrigation provided for a significantly greater optimal irrigable area. It also gave significantly higher production for large irrigable areas when water supply became inadequate.