Physical Modelling Study on Sediment Removal of Sungai Habu and Sungai Ringlet, Cameron Highlands

Numbers of reservoir in Malaysia has experienced excessive sedimentation problem due to soil erosion caused by rapid urbanization, infrastructure development and uncontrolled agricultural activities. With an increased in sediment deposition rate, the approximated useful life of the reservoir is significantly shorten. This also reduces the reservoir power generation capacity and dangerously affects dam stability and flood control storage. The aim of this study is to simulate alternative method for efficient sediment removal in Ringlet reservoir. The construction of physical sediment removal model of Ringlet Reservoir took place in the Hydraulic and Instrumentation Laboratory, National Hydraulic Research Institute of Malaysia (NAHRIM), with geometric scale effect of 1:30. Sungai Habu and Ringlet were tested up to three different ARI of 1, 5 and 100. Groyne was identified as control mitigation structure for sediment removal and total of 23 groynes were constructed. The finding showed that the gross deposition and erosion areas increased as the return period rose. It was also noticed that bed sediment in 100 year ARI was eroded more and further than 1 and 5 year ARI due to local scour resulted from the flow transition from fixed bed to mobile bed. The morphological changes occurred at Habu is due to the local flow. The movement of bed sediment at Habu end were deposited before the check dam and was not travel further downstream. The results of Ringlet showed that the sediment was deposited mostly before the first check dam for 1 year ARI. Sediments may further be transported for 5 ARI and 100 years ARI which then deposited before the second check dam.