Sediment Response to Tropical Storms in Singapore's Residential Catchments

Abstract

Sediment response from tropical storms was investigated in two high-density residential catchments, Jurong West (JW, 69 ha, 84% impervious) and Ang Mo Kio (AMK, 35 ha, 60% impervious), Singapore. Quick runoff responses were observed and more pervious runoff events occurring in AMK. Clockwise hysteresis pattern was commonly observed but the influence of tropical storm events, construction activities and poor vegetation cover have also resulted in eight-shaped, clockwise eight-shaped and random hysteresis patterns. Double corrective methods were applied in event-based rating curves and the annual sediment yield of JW and AMK were 289 and 338 tonnes/ km2/ yr respectively. Dissolved organic carbon (DOC) levels showed identical patterns of delivery as SSCs patterns during storm events. During storm events, high DOC levels were observed before peak discharge but decline due to dilution effects from higher discharge volumes. High levels of DOC were attributed to transportation surfaces in both catchments.