Determination Of Rainfall-Runoff Characteristics In An Urban Area: Sungai Kerayong Catchment, Kuala Lumpur

Rainfall-runoff characteristics of Sungai Kerayong catchment will be discussed in this article. The catchment represents an urban catchment with rapid growth rate due to urbanization process. A total of 90 independent storm events which were selected randomly for 5 years period were analyzed to determine the rainfall-runoff relationship. The catchment which has the area of 48.3km2 was divided into three sub catchments and the landuse map of the area was created using digital topographic maps and satellite images. The amount of runoff generated was estimated and the analysis was carried out by selecting storm events randomly. Finally, a linear regression between rainfall depth and amount of runoff generated indicates 77 % of impervious area in the catchment with estimated depression storage of 1.4mm. Further, the estimation of time of concentration (tc) will be discussed. The estimation of tc will be based by assessment on a total of 20 direct runoff hydrographs from the catchment. The tc is defined as the time between the center of mass rainfall excess and the inflection point on the recession of the direct runoff hydrograph. The average value of tc obtained from the analyzed hydrographs is 139 minutes and will be compared with four empirical time of