http://msmaware.com/blog/msma-manual-saliran-mesra-alam-malaysia-urban-stormwater-management-manual-for-malaysia/ Ph 6012 710 2620 Manual Saliran Mesra Alam Malaysia (MSMA), or in English the Urban Stormwater Management Manual for Malaysia is the urban drainage design standard first issued by the Department of Irrigation and Drainage Malaysia (D.I.D) in 2000. It is required by law for all engineers in Malaysia to build drainage works to fullfil the requirements of MSMA. 11 years after its first publication, DID has completely revised the first edition of MSMA (MSMA1) with the publication of the second edition (MSMA2). There are numerous alterations in the second edition include (taken from case studies done for Kuala Lumpur): 1. The design storm has increased by up to 126% for 10 out of the 14 rainfall stations in Kuala Lumpur. 2. The design discharge using the Rational Method has increased by up to 131% for commercial and city area. 3. The Site Storage Requirement for OSD for a factory lot in Kuala Lumpur has increased by up to 235%, 4. The volume of a detention pond has increased by up to 130%. The hike in the magnitudes of the main design parameters as described above can be attributed to the differences between the first and the second editions of MSMA as follows: 1. Longer storm data covering 100 more storm stations in Peninsular Malaysia. This gives rise to in higher rainfall intensities for certain durations and ARI's. 2. West Malaysia is now divided into 5 regions for the determination of the storm temporal pattern, compared to previously where it was divided into east and west coast of the Peninsula. The differences in temporal patterns give rise to dissimilar hydrograph peaks and shapes. 3. The coefficient of runoff in the Rational Method is now set according to the types of landuse, and not influenced by storm durations and intensities, and whether a catchment is urban/rural in condition. This resulted in differences in the estimated peak discharge. 4. The Time-Area Method in the second editon is affected by the differences in the storm intensites, temporal patterns and the loss model used. For Kuala Lumpur it is noted that the storm intensities have increased and the storm temporal pattern is more peaky, thus resulting in a more peaky discharge hydrograph. 5. The Site Storage Requirement (SSR) based on the Approximate Swinburne Method in the second editon is higher than that using the Swinburne Method in MSMA1. MSMA2 used the approximate method based on a set of approximation tables and this has resulted in an over estimation of the Site Storage Requirements. 6. The volume of a detention pond has increased using the second editon compared to MSMA1 because of the increase in the storm intensities, temporal patterns and the choice of loss rate. In view of the many differences in computational methods between the first and second editions of MSMA, a tool is developed to help engineers to perform the computations using both editions precisely and to allow comparison be made of their differences speedily. The tool is a drainage design software designed for MSMA. The software is created by Ir. Dr. Quek Keng Hong- a practising professional engineer in Malaysia. MSMAware also covers the East Malaysian state of Sarawak where more than a dozen storm stations and their temporal patterns are programmed into the software. DETENTION BASIN : 00:00:05 detention basin 00:00:05 design storm 00:00:06 design rainfall 00:00:07 temporal pattern 00:00:08 rainfall temporal pattern detention basin Ph 6012-7102620

• published: 21 Oct 2015
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