Physical flood modelling evaluation of river meandering channel in tidal effected reach

Abstract

Flood is one of the disasters in this country where around 29,000 km² or 9% of the country was exposed to it. Understanding the flood phenomena along the river and flood plain would be able to help in the assessment of the impact of human activity in the river basin. Modelling of river and flood plain will form as a basis for this understanding. The objectives of this study are to develop a physical model of river meandering channel in tidal effected reach and to assess the flood plain and water level for various flow under existing conditions and flood mitigation measures using cut off system. Scope of this study includes the developement of physical model and the assessment of flood plain and water level. It includes gathering the available data and construction of physical model for parts of Selangor River at NAHRIM laboratory. The model was tested for different flows with various conditions. In the first part, the test was carried out at low water, mean sea and high water for existing alignment. In the second part of the study, cut off was intruduce at one stretch of the channel section and similar test cases were carried out. Readings for velocity and water levels were taken at eight stations along the river channel and another eight locations in the flood plain area. The results of the experiments shows that the water levels increases as the flow increases and causes the flood. The recorded velocity was inconsistent and fluctuates but reduces in value as the flow increases. The introduction of cut off to the channel reduces the water levels and proved to be effective to solve flood problem on meandering rivers to certain discharge. The experiment also shows flood does not occurs near the rivermouth under all conditions.