Flooding on hill site of Bukit Jambul development area

Abstract

Hydrological consideration of a hill site development is important due to the development may subject to significant impact as a result of a huge water catchment from the uphill area. The study area is one of hill site development which suffer from flooding incident which occurred every years and it has marked the worst flooding incident on November 2015. Case study approach was carried out to determine the main cause of the flooding. Study of the site area revealed that the actual catchment for the site was significantly huge and the site is lies in between two major depressions point. Three streams was identified that contribute to the surface runoff. Two cases of analysis were adopted to simulate different rainfall that based on the water catchment area. First is consideration of water catchment within the site boundary and second is consideration of uphill water catchment and the natural streams and the peak discharge of the design rainfall was checked against the drainage capacity. The result of the analysis shows that the existing drainage capacity was only designed to cater maximum Qpeak of 1.71 m3/s. However, with the consideration of water catchment from the uphill area the drain capacity has exceeded about 90% in order to flow a surface runoff Qpeak of 12.53 m3/s The result of the study shows that the existing drainage system was not designed for the uphill catchment and caused the area to be flooded.