Title: Comparison of water supply dams' spillway performance in Malaysia

Authors: Heng Hock Hwee; Hii Ching Poon; Pan Wang Fook

Addresses: Jurutera Adda Sdn Bhd, Bangunan USC, No. 683, Lorong Song 1A, Off Jalan Song, 93350 Kuching, Sarawak, Malaysia ' Jurutera Adda Sdn Bhd, Bangunan USC, No. 683, Lorong Song 1A, Off Jalan Song, 93350 Kuching, Sarawak, Malaysia ' Department of Civil Engineering, Faculty of Engineering and Built Environment, SEGi University, Jalan Teknologi, Kota Damansara, 47810 Petaling Jaya, Selangor, Malaysia

Abstract: This paper compares the risk of dam overtopping of two rolled compacted concrete (RCC) dams in Malaysia. Uniform methodology was carried out by selecting an appropriate probable maximum precipitation (PMP) series, performing a catchment PMP/PMF (probable maximum flood) rainfall runoff routing and finally, routing the inflow hydrographs through the reservoir water body. The critical PMP/PMF reservoir outflows and their corresponding flood rises were also compared. Both dams are considered safe using the current PMP series. The roles of surcharging volumes above the top water level of the reservoir were also demonstrated via their respective flow attenuation capabilities by their surcharging volume. This paper also demonstrates a close relationship can be forged between the product of spillway width and headroom vis-à-vis the catchment areas draining at the dam sites. The product represents a trade-off between a larger spillway vis-à-vis lower headroom, vice versa. Both Kinta and Bengoh dams' spillway factors are consistently higher than the regressed curve using a vast database of existing dams and reservoirs in Malaysia.

Keywords: rolled compacted concrete; RCC; probable maximum precipitation; PMP; probable maximum flood; PMF; dam overtopping; flood design; Malaysia; flooding; spillway performance; rainfall runoff; inflow hydrographs; reservoirs; dams; surcharging volumes; headroom.

DOI: 10.1504/IJHST.2014.064412

International Journal of Hydrology Science and Technology, 2014 Vol.4 No.1, pp.39 - 57

Published online: 30 Aug 2014 *

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