Evaluation of Scour and Deposition in Malaysia Rivers Undergoing Training Works : Case Studies of Pari River and Kerayong River
Numerous flood mitigation projects are being implemented throughout the country especially in urban areas. The occurrence of floods after the project completions shows the project completions shows the existence of damages to the rigid bank walls and serious problems of erosion and deposition.
Referring to the above problem, two completed flood mitigation projects, namely, Pari River Flood Mitigation Project Phase 2, Ipoh and Kerayong River Flood Mitigation Project Phase 4, Kuala Lumpur were chosen as case studies. The aims of the study are to evaluate the capacity of newly improved channels for both projects in accommodating the designed flood discharge and the stability of the bank protection structures taking into account effects of erosion and deposition using two mathematical models, namely, FLUVAL –12 (“Mathematical Model for Erodible Channel”) dan HEC – 6 (“Scour and Deposition in Rivers and Reservoir”). This research also emphasis sediment transport in alluvial river since it can be considered as a new subject in this country.
Result of this study on sediment transport in several rivers in Kinta District show that the existence of relationships between bed load and discharge, total bed material load and discharge, and between bed load and bed material. Graf’s (1968) and Yang’s (1972) sediment transport equations are found to be suitable for predict the sediment transport inall the rivers studied. Calibration results for Pari River show that FLUVAL – 12 using Graf’s give the closest resemblance to measured flood levels, flow rating curve at Manjoi Bridge and the location of damaged rigid bank walls. Calibration results using HEC – 6 shows that this model can be used for estimating the cannel capacity but not suitable for analyzing the stability of the bank protection structures at Pari River.
Simulation result of Kerayong River shows that Yang’s sediment transport produces a better result compared to Graf’s equation (which is more suitable for Pari River). This indicates hat different rivers may behave differently. Hence the problems pertaining to each river should be treated individually.