Imperfect irrigation planning associated with serial river flow pattern and irrigation management: Case study of Way Sekampung irrigation project, Indonesia
2001
Nagayo, N. (Japan International Cooperation Agency, Tokyo) | Satoh, M.
The effectiveness of imperfect irrigation planning in run-of-the river irrigation is discussed through a tropical region case study in Way Sekampung Irrigation Project, Indonesia, where the year is clearly divided into rainy and dry seasons. First, it clarifies that the yearly paddy cropping intensity under the present planning method, adopting a perfect irrigation system based on the 5-year probable low flow, is limited at 140% because of low flow during dry season. It also shows that the historical water deficits in this project has not resulted in reduction of harvesting area if the cumulative water deficit rate during droughts was less than 110%. Second, the water use for yearly paddy cropping intensities of 140% up to 180%, with an interval of 10% is simulated and compared with the 20 year historical river flow discharge to evaluate the occurrence of accumulated water deficit. It shows that the occurrence frequency of water shortage is 0.5 and 1.0 times a year at cropping intensities of 140% and 180%, respectively, and most of the water shortages have the cumulative water deficit rates of less than 110%. It concludes that imperfect irrigation planning is one of the feasible alternatives in run-of-the-river irrigation schemes as long as a stable water management system is established.
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