Sediment transport modeling for Kulim River – A case study

Rapid urbanization has accelerated impact on the catchment hydrology and geomorphology. This rapid development which takes place in river catchment will result in higher sediment yield and affect river morphology and river channel stability; it also becomes the main cause for serious flooding in urban areas. Therefore, it is necessary to predict and evaluate the river channel stability due to the existing and future developments. This study proceeds at Kulim River in Kedah state, a natural stream in Kedah, Malaysia. The FLUVIAL-12 model, an erodible-boundary model which simulates inter-related changes in channel-bed profile, width variation and changes in bed topography was selected for this study. Engelund-Hansen formula and roughness coefficient n = 0.030 were found to be the best combination to represent the sediment transport activity in the study reach, where good agreements were obtained for both water level and bed profiles between the measured data and predicted results by FLUVIAL-12 model. The model simulation results for existing conditions, future conditions and long-term modeling show that the sediment size and channel geometry in Kulim River changed significantly. However, modeled results show that future changes in cross sectional geometry will be limited and erosion along the reach will slow down from 2006 to 2016, thus Kulim River was predicted to be stable at most locations.