Stable channel analysis with sediment transport for rivers in Malaysia: A case study of the Muda, Kurau, and Langat rivers

摘要

Assessments of a stable channel were done to evaluate the conditions of three rivers in Malaysia,using an analytical method that modifies the stable channel flowchart developed by Chang(1988)and Ariffin(2004).The analytical approach was selected to calculate the suitable dimensions for a stable channel,using equations that describe the physical relation of sediment transport,flow resistance,and dynamic equilibrium.Measured field data were used as the input data for the stable channel program,which then processed the data until the input discharge was equal to the output discharge.However,this method depends on the accuracy of the sediment transport equation that is used in the stable channel design.Existing equations recommended by the Department of Irrigation and Drainage(DID),Malaysia,were found to be unsuitable because of their low discrepancy ratio(DR)values,which were below 42%.These are the equations of Engelund and Hansen(1967)and Yang(1979),as well as existing local equations from Ariffin(2004)and Sinnakaudan et al.(2006).Therefore,revised equations were developed in the current study to increase the accuracy of the total bed material load equations for use in Malaysian rivers.The newly revised Ariffin(2004)and Sinnakaudan et al.(2006)equations yielded better DRs of 66.34 and 64.49%,respectively.River assessments done on the Kurau River(a small river),the Muda River(a medium-size river),and the Langat River(a large river)show that these rivers have experienced different levels of erosion.Only the Kurau River was found to have minimal erosion and sedimentation levels.Conversely,stable channel assessments for the Muda River and the Langat River revealed that both rivers had experienced severe erosion,due to excessive sand mining.Almost all the cross section sampling points on the Muda River and Langat River were deeper than the suggested stable channel heights.