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Evaluation of Scour and Deposition in Malaysia Rivers Undergoing Training Works : Case Studies of  Pari River and Kerayong River

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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.