ASSESSING THE PERFORMANCE OF VARIOUS ON-SITE DETENTION POND DESIGN METHODS BASED ON MSMA 2 GUIDELINES

Flash flood and monsoon flood are the common disasters caused by improper storm water management. Hence, on-site detention plays an indispensable role in the storm water management to reduce the probability of flood occurrences. The design method adopted determines the cost-effectiveness and usefulness of the designed on-site detention facility. In this study, on-site detention facility of three developments were analysed using two methods: the Simplified Method and the Modified Puls Method. It was found that Modified Puls Method is the more economical method compared to the Simplified Method. Moreover, the accuracy of the on-site detention system has affected the magnitude of rainfall intensity corresponding to various storm duration and ARI (Average Recurrence Index). The IDF (Rainfall Intensity- Duration-Frequency) curves provided in MSMA 2 (Urban Storm water Management Manual for Malaysia 2nd Edition) was not up to the current year. Thus, IDF curves were developed for the rainfall stations of each development data using the Arithmetic Mean Method and followed by mass curve analysis to check the filled rainfall data consistency.