Effectiveness of check dam to control soil erosion in a tropical catchment (The Ulu Kinta Basin)

Abstract

Abstract Check dams are commonly used to stabilize sedimentation, reduce the through water velocity, limit catchment erosion, and increase the reservoir storage capacity of a dam. In the study area, three check dams were constructed before the Sultan Azlan Shah Dam by the Perak Water Board (LAP) to control sedimentation. This area is an active erosion environment because of the erodible material in the stream and check dams. The effectiveness of the check dams (CD1 to CD3) was investigated to identify how the construction of such transverse structures can be used to control the soil erosion rates and the reservoir storage capacity of the dam. Toward this end, first geomorphic maps of the channel bed in the upstream and the downstream region were obtained. Then, the distribution of bed material in the study area was determined through sampling at 20 individual locations along the river. Finally, the impact of check dams on settling particles was calculated on the basis of critical velocity. Cross sections of the river showed a narrow, steep channel upstream, and a wide, shallow channel downstream. The median grain size distribution (D 50 ) was between 2 mm before CD1 to 0.082 mm after CD3 with a minimum measured velocity of 0.24 m/s. The critical velocity showed a significant correlation with measured velocity. Furthermore, the velocity of the river and the dimension of the check dams were suitable for trapping coarse particles, especially at the last check dam (CD3).