HYDROPOWER RESERVOIR FOR FLOOD CONTROL: A CASE STUDY ON RINGLET RESERVOIR, CAMERON HIGHLANDS, MALAYSIA Jansen Luis 1 , Lariyah Mohd Sidek 2 , Mohamed Nor Bin Mohamed Desa 3 , and Pierre Y. Julien 4 1 Senior Engineer, Generation Asset Development, TNB and Post Graduate Student, Department of Civil Engineering, Universiti Tenaga Nasional, Malaysia 2 Assoc Prof, Department of Civil Engineering, Universiti Tenaga Nasional, Malaysia 3 Professor, Department of Civil Engineering, Universiti Tenaga Nasional, Malaysia 4 Professor, Department of Civil Engineering, Colorado State University, USA ABSTRACT: Hydropower reservoir typically requires water level to be kept at minimum design level to store as much energy as possible for daily hydropower generation as well as to prevent any spillage at dam. However, as the reservoir storage volume is lost due to sedimentation, energy output from plant is affected, reservoir gradually losses capability to contain large flood inflows and control release of flood discharge through the spillway is inevitable (Abrishamchi et al., 2011; Shafiee et al., 2012) [1,16]. Results from the study show that the reservoir is only capable to storing 2.3 mil m 3 of water as compared against 6.7 mil m 3 at a pool elevation of 1071 m, which is a reduction of almost 65.7%. Meanwhile energy generation at Jor Power Station was found to be operating below the 200 GWh or at 62.5% efficiency at an average 2.5 mil m 3 live storage well below the original design capacity of 320 GWh. With the reduction in storage volume, the requirement for control release during floods is expected. Results from numerical simulation indicates that with a control release of 4-5 m 3 /sec during flushing, the depth of water would be 0.8 –1 m and the total top width of flow is 7-8 m. Field test is also conducted to verify the findings of the simulation. Initial analysis from the topographic survey shows that the downstream river is incapable to contain the flood release from the reservoir due to encroachment of population into the river reserves. The study concludes by recommending both structural and non-structural measures to safety mitigate the risk of downstream flooding during the control release from the reservoir. Keywords: Hydropower, flood simulation, control release, flood risk mitigation. 1. INTRODUCTION All dams are designed to store flood-waters, primarily for the benefit of human beings. The damming of streams and rivers has been an integral part of human civilization from its early history. Reservoirs and dams are constructed by human to deal with the need of water and power. Dams and reservoirs are constructed primarily to function as multipurpose functions including as flood control, drinking water, agricultural water supply, hydro power generation, recreation and others [Braga et al., 1998; Verghese, 2001; Vyas, 2001) [5, 18,19]. © International Science Press (India) ISSN : 0976-6219 JFE JOURNAL OF FLOOD ENGINEERING 4(1) January – June. 2013; pp. 87–102