EFFECTS OF CANAL OPERATION ON SEDIMENT TRANSPORT SUNSARI MORANG, NEPAL

摘要

Currently, more and more irrigation schemes are being modernized to increase the efficiency and to meet the growing needs of food with the limited water and land resources. In an effort to make those schemes more flexible, efficient and reliable the number of flow control structures has sharply increased during the modernization and development of the schemes. Operation of these structures makes the flow non-uniform and unsteady and as a consequence the sediment transport in the system changes. Present canal designs include sediment transport criteria only for the design discharge and normal flow conditions. The performance of the canals under changing flow, structure control and operation plans is seldom tested during the design and operation. The Sunsari Morang Irrigation Scheme (SMIS) in Nepal is being modernized and the sediment management is one of the major issues in the design. One of the modernized secondary canals (S9) has been studied to find out the effect of water delivery schedules and operation of control structures on sediment transport. The sediment transport model SETRIC has been used for analysis of the canal operation and flow control. Suggested operation and control in the design was not followed during the irrigation season. The results of the simulation show that the deposition is larger than when the canal was operated according to the design for the same water flow and sediment inflow.