Factors Controlling the Suspended Sediment Yield During Rainfall Events of Dry and Wet Weather Conditions in A Tropical Urban Catchment

The catchments of the Klang and Ampang Rivers are two sub-catchments that drain into the main Klang River, Selangor, Malaysia. Due to the development and siltation processes, the current capacity of the Klang River in the city centre is insufficient for accommodating the excess flood flow during major events, and, therefore overflows the riverbanks causing flash floods to occur in the Kuala Lumpur city centre. This study investigates the relationship between the rainfall, discharge and suspended sediment transport and its variations during the dry and wet periods in tropical sub-catchments; identifies the different hysteresis types of single flood events in the suspended sediment concentration/discharge relationships in the dry and wet periods, and determines the relationship between the types of single event hysteresis loops and the hydrological and sediment responses. Principal component analysis was performed to examine factors that have a major influence on the suspended sediment yields during both the dry and wet periods. The clockwise and counter-clockwise hysteresis loops occurring mostly during the dry period, can be described as events with moderate total rainfall, rainfall intensity (less than 10 mmh⁻¹), average discharge and suspended sediment load. Counter-clockwise events occurring during the wet period are associated with low total rainfall, rainfall intensity, average discharge and suspended sediment load. The clockwise and counter-clockwise events that occurred in the wet period are related to events with a relatively high and low moisture condition, respectively. The figure-eight and complex hysteresis loop events occur predominantly during the wet period. The complex loop events occurred mostly during the wet period generates the highest suspended sediment load. The complex loop events occur mostly during the wet period generated the highest suspended sediment load.