design storm software Call 6012-710-2620

design storm software Call 6012-710-2620

http://msmaware.com/blog/msma-software/
Ph 6012 710 2620

In 2000 the Department of Irrigation and Drainage Malaysia first printed the stormwater drainage design guideline known as the Urban Stormwater Management Manual or the Manual Saliran Mesra Alam Malaysia, MSMA. It is mandatory for all engineers in Malaysia to build drainage works to comply with the requirements of MSMA. More than ten years after its first publication, DID has completely amended the first edition of MSMA (referred to as MSMA1) with the release of the second edition (referred to as MSMA2). There are many differences in the second edition including (taken from case studies done for Kuala Lumpur):

10 out of the 14 storm stations in Kuala Lumpur have its design rainfall risen by up to 124%.
The design discharge using the Rational Method has risen by up to 131% for commercial and city area.
The Site Storage Requirement for On-Site Detention for a factory lot in Kuala Lumpur has risen by up to 233%,
The volume of a detention pond has risen by up to 128%.

The differences between the first and the second editions of MSMA give rise to the rise in the values of the main design parameters as follows:

135 stations in Peninsular Malaysia with longer precipitation data. This results in higher storm intensities for certain durations and ARI's.

Peninsular Malaysia is now divided into five regions for the determination of the temporal pattern, compared to the first edition where it was divided into east and west coast of the Peninsula. The differences in temporal patterns give rise to different hydrograph peaks and shapes.

Not dependent on rainfall durations and intensities, and whether a catchment is urban/rural in condition, the coefficient of runoff in the Rational Method is now established according to the types of landuse. Differences in the estimated peak discharge is observed .

The differences in the rainfall intensites, temporal patterns and the loss model used all affected the Time-Area Method in MSMA2. The rainfall intensities for Kuala Lumpur have increased and the temporal pattern is more peaky, giving rise to a more peaky discharge hydrograph.

The Site Storage Requirement (SSR) based on the Approximate Swinburne Method in MSMA2 is higher than that using the Swinburne Method in the first edition. MSMA2 used the approximate method based on a set of approximation tables and this has resulted in an over estimation of the SSR's.

Compared to the first edition, the increase in the rainfall intensities, temporal patterns and the selection of loss rate have caused a rise in the volume of a detention pond using MSMA2.

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 accurately and to allow comparison be made of their differences speedily. A urban drainage design software has been created for MSMA. Ir. Dr. Quek Keng Hong- a practising engineer in Malaysia is the programmer of the software. MSMAware also covers the East Malaysian state of Sarawak where more than a dozen rainfall stations and their temporal patterns are included into the software.





design storm software Call 6012-710-2620








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