Optimized Operation of Kainji Reservoir

Abstract

Niger River is the third largest river in Africa and it is impounded in Nigeria at Kainji and Jebba for the sole purpose of generating electricity. Kainji Reservoir has a capacity of generating 760 mW of electricity, while Jebba Reservoir which is 100 km downstream of Kainji Reservoir, has a capacity of generating 540 mW. Flooding of the plain downstream of the reservoirs is an annual phenomenon, especially in September. On the other hand, water level in the reservoirs is low between March and May resulting in low head for generating electricity. This study determines an operation policy for Kainji Reservoir using Stochastic Dynamic Programming. The policy was compared with the operation rules between 1996 and 1999. Inter-annual variation in inflow to Kainji Reservoir was attributed to flow in September when peak rainfall occurs in the catchment area that lies within Nigeria. The operation rules adopted by Managers between 1996 and 1999 could not handle instantaneous high inflow between August and September because the water level in the reservoir was high prior to the arrival of such flow. Thus, there was high spillage so as to avoid structural failure of the dam. It was also observed that volume of water released from the reservoir remained high after the cessation of high inflow. It is recommended that the managers should adopt an operation policy that could handle inter-annual variation in inflow to the reservoir so as to maximize the benefit of impounding the water of River Niger and also minimize the annual flooding of the river plain.