Dr. Quek's tips on MSMA (Part 25)- Workshop F Preview Video

Ir. Dr. Quek Keng Hong has a PhD and a Master’s degree in water resources from the University of NSW, Australia. Dr. Quek is a consulting engineer by practice and specialises in the field of urban drainage and hydrology. He has conducted many training workshops and seminars on MSMA. Dr. Quek is currently a committee member of the Water Resources Technical Division (WRTD). 1. Introduction This paper reviews the design of On-Site Detention (OSD) using the first and second editions of MSMA- referred to herein as MSMA (2000) and MSMA (2011), respectively. MSMA is an acronym for the Manual Saliran Mesra Alam (the Urban Stormwater Management Manual for Malaysia) published by the Department of Irrigation and Drainage (D.I.D, 2000 and 2011). The review was based on case studies in Kuala Lumpur involving an industrial lot and a low density residential development. The magnitudes of the Permissible Site Discharge (PSD) and the Site Storage Requirement (SSR) are computed by the following three approaches and their differences compared: 2 ? Using the Swinburne Method in MSMA (2000) where a set of formulas for PSD and SSR are used to compute their values. ? Using the Approximate Swinburne Method in MSMA (2011) where a set of approximation tables are used to determine the PSD and SSR values. ? Using the rainfall and discharge data from MSMA (2011), but instead of computing the PSD and SSR using the Approximate Swinburne Method in MSMA (2011), the formulas from the Swinburne Method in MSMA (2000) are used. This is referred to as the Exact Swinburne Method (ESM). 2. Design of On-Site Detention 2.1 OSD Sizing in MSMA (2000) In MSMA (2000), the method of estimating Permissible Site Discharge (PSD) and Site Storage Requirement (SSR) is based on the Swinburne Method developed at the Swinburne University of Technology in Melbourne, Australia. The method uses the Rational Method to calculate site flows, and utilises a non-dimensional triangular site hydrograph based on the triangular design storm method as shown in Figure 1.