WATER REQUIREMENT FOR PADDY CULTIVATION AND FISH POND ON KELINGI IRRIGATION AREA, SOUTH SUMATERA, INDONESIA

Indonesia is likely to face water crisis due to water mismanagement especially because of inefficient water usage.Agriculture, the important sector consumes the most available fresh water but water use inefficient.For the future, it is important to increase the agricultural water efficiencies and productivities to meet the uncertain water availability.Fish pond farming integrated agriculture practices are seen as a proficient utilization of the water.This study aimed to evaluate water requirement and water balance for rice cultivation based on Mock Tank Model and fish pond farming based on Delft Hydraulics Model at Kelingi irrigation area, Musi Rawas District.Monthly rainfalls on this area were in the range of 197 -394.7 mm, very suitable for the agricultural activities.In fact, the effective rainfall was not sufficient to meet the water requirement of rice cultivation in certain period of the plant growth therefore the water requirement should be supplied from irrigation facilities.The highest value of water requirement occurred in the first half month of January (NFR = 205.32mm) and the lowest one in the first half month of November (NFR = 84.40mm).Furthermore, the highest amount of the water discharge at the primary intake for watering the whole area in a half month occurred in the second half of January (Q80 = 19,409.56l sec -1 ) while the lowest available of water discharge occurred in the first half of April (Q80 = 5,425.09l sec -1 ).The water requirement for the existing fish ponds farming requires around 3,284.35 l sec -1 to meet the water needs through the year, and this value is about 28.97% from the reliable irrigation discharge at the intake of the Kelingi irrigation facility.Avoiding water use competition between both the agriculture activities, the suitable cropping pattern is rice-rice-corn/peanuts/soybean.