Thursday, November 19, 2015

Urban Stormwater Management Manual for Malaysia Tel 6012)-7102620


Urban Stormwater Management Manual for Malaysia Tel (6012)-7102620






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

The urban drainage design standard first published by the Department of Irrigation and Drainage Malaysia in 2000 is the Urban Stormwater Management Manual for Malaysia or the Manual Saliran Mesra Alam Malaysia (MSMA). Fullfilment of the requirements of MSMA when designing drainage system is required by law of all engineers in Malaysia. Eleven years after its first publication, DID has completely updated the first edition of MSMA (MSMA1) with the publishing of the second edition (MSMA2). There are numerous alterations in the second edition including the following (based on case studies done for Kuala Lumpur):

ten out of the fourteen storm stations in Kuala Lumpur have its design rainfall increased by up to 126%.
For commercial and city area, the design discharge using the Rational Method has increased by up to 131%.
The Site Storage Requirement for OSD for a factory site in Kuala Lumpur has increased by up to 235%,
The storage of a detention pond has increased by up to 130%.

The hike in the magnitudes of the main design parameters as outlined above can be attributed to the differences between the first and the second editions of MSMA as follows:

135 storm stations in Peninsular Malaysia with longer rainfall 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 rainfall 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 dissimilar hydrograph peaks and shapes.

Not affected by rainfall durations and intensities, and whether a catchment is urban/rural in condition, the coefficient of runoff in the Rational Method is now determined according to the types of landuse. This resulted in differences in the estimated peak discharge.

The Time-Area Method in the second editon is affected by the differences in the rainfall intensites, temporal patterns and the loss model used. For Kuala Lumpur it is noticed that the rainfall intensities have increased and the rainfall temporal pattern is more peaky, thus resulting in a more peaky discharge hydrograph.

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. The approximate method in the second editon has caused an over estimation of the SSR's.

The storage of a detention pond has increased using the second editon compared to MSMA1 because of the increase in the rainfall intensities, temporal patterns and the choice of loss rate.

In view of the many differences in computational procedures between the first and second editions of MSMA, a tool is developed to help engineers to carry out the computations using both editions accurately and to allow comparison be made of their differences quickly. The tool is a stormwater design software designed for MSMA. The software is created by Ir. Dr. Quek Keng Hong- a practising professional engineer in Malaysia. MSMAware also contains more than a dozen rainfall stations and their temporal patterns in the East Malaysian state of Sarawak.

















Urban Stormwater Management Manual for Malaysia Tel (6012)-7102620













https://www.youtube.com/watch?v=lMzPpnakrEs




Manual Saliran Mesra Alam Malaysia Tel 6012-7102620


Manual Saliran Mesra Alam Malaysia Tel 6012-7102620
http://www.youtube.com/watch?v=KcO5a_DbJj4

Intensity Frequency Duration Call 6012-710-2620


Intensity Frequency Duration Call 6012-710-2620
http://www.youtube.com/watch?v=vHYqvUMWzWY

Manual Saliran Mesra Alam Malaysia Tel 6012-7102620


Manual Saliran Mesra Alam Malaysia Tel 6012-7102620






http://msmaware.com/blog/msma-urban-stormwater-management-manual-for-malaysia-training-seminars-workshops-and-software/
Phone 6012-710-2620

In 2000 the Department of Irrigation and Drainage Malaysia first printed the urban drainage design guideline known as the Urban Stormwater Management Manual for Malaysia or the Manual Saliran Mesra Alam Malaysia, MSMA. It is compulsory for all engineers in Malaysia to build drainage works to comply with the requirements of MSMA. 11 years after its first publication, DID has completely revised the first edition of MSMA (MSMA1) with the release of the second edition (MSMA2). With reference to the case studies completed for Kuala Lumpur, there are a lot of alterations in the second edition include:

For Kuala Lumpur it was found that the design rainfall has risen by up to 126% for ten out of the 14 storm stations.
The design flow using the Rational Method has risen by up to 131% for commercial and city area.
The Site Storage Requirement for OSD for a factory site in Kuala Lumpur has risen by up to 235%,
Detention basin has risen by up to 130% in the volume.

The hike in the values of the main design parameters as outlined above can be attributed to the differences between the first and the second editions of MSMA as follows:

135 storm stations in Peninsular Malaysia with longer precipitation data. The storm intensities for most Average Recurrence Intervals have increased.

Compared to the first edition where it was divided into east and west coast of the Peninsula for the determination of the temporal pattern, West Malaysia is now separated into five regions. The different hydrograph peaks and shapes caused by the differences in temporal patterns.

The coefficient of runoff in the Rational Method is now set according to the types of landuse, and not affected by rainfall durations and intensities, and whether a catchment is urban/rural in condition. Differences in the estimated peak flow is observed .

The differences in the rainfall intensites, temporal patterns and the loss model used all influenced the Time-Area Method in MSMA2. For Kuala Lumpur it is noticed that the rainfall intensities have increased and the temporal pattern is more peaky, thus giving rise to a more peaky flow hydrograph.

The Approximate Swinburne Method in MSMA2 gives higher Site Storage Requirement (SSR) than the Swinburne Method in MSMA1. The approximate method in MSMA2 has resulted in an over estimation of the SSR's.

Compared to MSMA1, the increase in the rainfall intensities, temporal patterns and the selection of loss rate have given rise to a rise in the volume of a detention basin using MSMA2.

A software program Is built to assist engineers to perform the computations using both editions accurately and to allow comparison be made of their differences speedily, in view of the many differences in computational procedures between the first and second editions of MSMA. The tool is a drainage design software developed for MSMA. The software is programmed 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 rainfall stations and their temporal patterns are programmed into the software.

















Manual Saliran Mesra Alam Malaysia Tel 6012-7102620













https://www.youtube.com/watch?v=KcO5a_DbJj4




Sunday, November 1, 2015

Rational Method Ph 6012-7102620


Rational Method Ph 6012-7102620






http://msmaware.com/blog/get-free-msma-newsletter/


Call 6012-710-2620





Manual Saliran Mesra Alam Malaysia (MSMA), or the Urban Stormwater Management Manual for Malaysia is the urban drainage design procedure first distributed by the Department of Irrigation and Drainage Malaysia (D.I.D) in 2000. It is compulsory for all engineers in Malaysia to build drainage works to comply with the requirements of MSMA. 11 years after its first publication, DID has completely updated the first edition of MSMA (MSMA1) with the release of the second edition (MSMA2). There are many changes in the second edition include (taken from case studies completed for Kuala Lumpur):





1. The design storm has risen by up to 126% for 10 out of the 14 storm stations in Kuala Lumpur.





2. The design flow using the Rational Method has gone up by up to 131% for commercial and city area.





3. The Site Storage Requirement for On-Site Detention for a factory lot in Kuala Lumpur has risen by up to 235%,





4. The storage volume of a detention basin has gone up by up to 130%.





The rise in the magnitudes of the main design parameters as outlined above can be due to the differences between the first and the second editions of MSMA as follows:





1. Longer precipitation data covering 100 more rainfall stations in Peninsular Malaysia. This gives rise to in higher storm intensities for certain durations and ARI's.





2. West Malaysia is now grouped 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 fixed according to the types of landuse, and not dependent on storm durations and intensities, and whether a catchment is urban/rural in condition. This resulted in differences in the estimated peak flow.





4. The Time-Area Method in MSMA2 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 giving rise to a more peaky flow hydrograph.





5. The Site Storage Requirement (SSR) based on the Approximate Swinburne Method in MSMA2 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 storage volume of a detention basin has risen using MSMA2 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 procedures 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 quickly. The tool is a drainage design software created for MSMA- which is known as the MSMAware. The software is developed by Ir. Dr. Quek Keng Hong who is a practising professional engineer in Malaysia. MSMAware also covers the East Malaysian state of Sarawak where more than a dozen storm stations in the state and their temporal patterns are included into the software.

















Rational Method Ph 6012-7102620










https://www.youtube.com/watch?v=XsDR9mTovKI




Tuesday, October 27, 2015

storm temporal pattern Phone 6012)-7102620


storm temporal pattern Phone (6012)-7102620






http://msmaware.com/blog/enquiry-about-msmaware-software/


Phone (6012)-7102620





Manual Saliran Mesra Alam Malaysia (MSMA), or the Urban Stormwater Management Manual for Malaysia is the stormwater drainage design standard first produced by the Department of Irrigation and Drainage Malaysia (D.I.D) in 2000. It is compulsory for all engineers in Malaysia to build drainage structures to comply with the requirements of MSMA. Eleven years after its first publication, DID has completely updated the first edition of MSMA (MSMA1) with the publishing of the second edition (MSMA2). There are a lot of alterations in the second edition including (based on case studies done for Kuala Lumpur):





1. The design rainfall has risen by up to 126% for 10 out of the fourteen storm 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 risen by up to 235%,





4. The storage of a detention pond has increased by up to 130%.





The hike in the values of the main design parameters as outlined above can be attributed to the changes between the first and the second editions of MSMA as follows:





1. Longer storm data covering 100 more stations in Peninsular Malaysia. This results in higher storm intensities for certain durations and Average Recurrence Intervals.





2. West Malaysia is now separated into 5 regions for the computation of the 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 established according to the types of landuse, and not affected by rainfall durations and intensities, and whether a catchment is urban/rural in condition. This resulted in changes in the estimated peak discharge.





4. The Time-Area Method in MSMA2 is affected by the changes in the rainfall intensites, temporal patterns and the loss model used. For Kuala Lumpur it is noted that the rainfall intensities have increased and the temporal pattern is more peaky, thus giving rise to a more peaky discharge hydrograph.





5. 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.





6. The storage of a detention pond has risen using MSMA2 compared to the first edition because of the increase in the rainfall intensities, temporal patterns and the choice of loss rate.





In view of the many changes in computational methods between the first and second editions of MSMA, a tool is developed to help engineers to carry out the computations using both editions precisely and to allow comparison be made of their changes speedily. The tool is a drainage design software created for MSMA- which is known as the MSMAware. The software is created by Ir. Dr. Quek Keng Hong who is a professonal engineer in Malaysia. MSMAware also covers the East Malaysian state of Sarawak where more than a dozen rainfall stations in the state and their temporal patterns are included into the software.

















storm temporal pattern Phone (6012)-7102620










https://www.youtube.com/watch?v=sDV19U4jlrA




Sunday, October 25, 2015

rainfall temporal pattern Call 6012-7102620


rainfall temporal pattern Call 6012-7102620






http://msmaware.com/blog/get-free-msma-newsletter/


Ph 6012-7102620





Manual Saliran Mesra Alam Malaysia (MSMA), which is also known as the Urban Stormwater Management Manual for Malaysia is the urban drainage design guideline first issued by the Department of Irrigation and Drainage Malaysia (D.I.D) in 2000. It is mandatory for all engineers in Malaysia to plan drainage structures to fullfil the requirements of MSMA. 11 years after its first publication, DID has completely updated the first edition of MSMA (MSMA1) with the publishing of the second edition (MSMA2). There are numerous differences in the second edition include (taken from case studies carried out for Kuala Lumpur):





1. The design rainfall has risen by up to 126% for 10 out of the 14 rainfall stations in Kuala Lumpur.





2. The design discharge using the Rational Method has risen by up to 131% for commercial and city area.





3. The Site Storage Requirement for OSD for a factory lot in Kuala Lumpur has risen by up to 235%,





4. The storage volume of a detention pond has risen by up to 130%.





The increase in the values of the main design parameters as outlined above can be attributed to the changes between the first and the second editions of MSMA as follows:





1. Longer storm data covering 100 more stations in Peninsular Malaysia. This gives rise to in higher rainfall intensities for certain durations and ARI's.





2. Peninsular Malaysia is now divided into five regions for the determination of the 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 fixed according to the types of landuse, and not dependent on rainfall durations and intensities, and whether a catchment is urban/rural in condition. This resulted in changes in the estimated peak discharge.





4. The Time-Area Method in the second editon is affected by the changes in the rainfall intensites, temporal patterns and the loss model used. For Kuala Lumpur it is noted that the rainfall intensities have increased and the 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 SSR's.





6. The storage volume of a detention pond has risen using the second editon compared to MSMA1 because of the increase in the rainfall intensities, temporal patterns and the choice of loss rate.





In view of the many changes in computational procedures 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 changes speedily. The tool is a drainage design software designed for MSMA- known as the MSMAware. The software is programmed by Ir. Dr. Quek Keng Hong who is a practising professional engineer in Malaysia. MSMAware also covers the East Malaysian state of Sarawak where more than a dozen rainfall stations in the state and their temporal patterns are included into the software.

















rainfall temporal pattern Call 6012-7102620










https://www.youtube.com/watch?v=LlYK_fA5z-A




design rainfall Ph 6012 710 2620


design rainfall Ph 6012 710 2620






http://msmaware.com/blog/documentation/


Phone 6012 710 2620





Manual Saliran Mesra Alam Malaysia (MSMA), or the Urban Stormwater Management Manual for Malaysia is the urban stormwater drainage design guide first distributed by the Department of Irrigation and Drainage Malaysia (D.I.D) in 2000. It is required by law for all engineers in Malaysia to design drainage works to fullfil the requirements of MSMA. 11 years after its first publication, DID has completely updated the first edition of MSMA (MSMA1) with the publishing of the second edition (MSMA2). There are a lot of 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 ten out of the 14 rainfall stations in Kuala Lumpur.





2. The design flow using the Rational Method has risen 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 risen 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 rainfall data covering 100 more storm stations in Peninsular Malaysia. This results in higher rainfall intensities for certain durations and ARI's.





2. West Malaysia is now grouped into five regions for the derivation 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 affected by storm durations and intensities, and whether a catchment is urban/rural in condition. This resulted in differences in the estimated peak flow.





4. The Time-Area Method in MSMA2 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 flow hydrograph.





5. The Site Storage Requirement (SSR) based on the Approximate Swinburne Method in MSMA2 is higher than that using the Swinburne Method in MSMA1. The second editon used the approximate method based on a set of approximation tables and this has resulted in an over estimation of the SSR's.





6. The volume of a detention pond has increased using MSMA2 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 procedures between the first and second editions of MSMA, a tool is developed to help engineers to carry out the computations using both editions precisely and to allow comparison be made of their differences quickly. The tool is a stormwater design software created for MSMA- which is known as the MSMAware. The software is developed by Ir. Dr. Quek Keng Hong who is a professonal engineer in Malaysia. MSMAware also covers the East Malaysian state of Sarawak where more than a dozen storm stations in the state and their temporal patterns are included into the software.

















design rainfall Ph 6012 710 2620










https://www.youtube.com/watch?v=06br-S3M0RY




detention basin Phone 6012-710-2620


detention basin Phone 6012-710-2620






http://msmaware.com/blog/get-free-msma-newsletter/


Ph 6012-710-2620





Manual Saliran Mesra Alam Malaysia (MSMA), which is known in English as the Urban Stormwater Management Manual for Malaysia is the urban drainage design procedure first released by the Department of Irrigation and Drainage Malaysia (D.I.D) in 2000. It is required by law for all engineers in Malaysia to design drainage structures to comply with the requirements of MSMA. 11 years after its first publication, DID has completely amended the first edition of MSMA (MSMA1) with the publishing of the second edition (MSMA2). There are numerous changes in the second edition include (based on case studies completed for Kuala Lumpur):





1. The design rainfall has increased by up to 126% for 10 out of the 14 rainfall stations in Kuala Lumpur.





2. The design flow 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 storage volume of a detention basin has increased by up to 130%.





The hike in the magnitudes of the main design parameters as described above can be due to the changes between the first and the second editions of MSMA as follows:





1. Longer precipitation data covering 100 more rainfall stations in Peninsular Malaysia. This gives rise to in higher rainfall intensities for certain durations and Average Recurrence Intervals.





2. West Malaysia is now grouped into five regions for the derivation 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 different hydrograph peaks and shapes.





3. The coefficient of runoff in the Rational Method is now determined according to the types of landuse, and not affected by rainfall durations and intensities, and whether a catchment is urban/rural in condition. This resulted in changes in the estimated peak flow.





4. The Time-Area Method in MSMA2 is affected by the changes in the rainfall intensites, temporal patterns and the loss model used. For Kuala Lumpur it is noted that the rainfall intensities have increased and the storm temporal pattern is more peaky, thus resulting in a more peaky flow hydrograph.





5. 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 Site Storage Requirements.





6. The storage volume of a detention basin has increased using MSMA2 compared to the first edition because of the increase in the rainfall intensities, temporal patterns and the choice of loss rate.





In view of the many changes 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 changes speedily. The tool is a stormwater design software developed for MSMA- known as the MSMAware. The software is written by Ir. Dr. Quek Keng Hong who is a professonal engineer in Malaysia. MSMAware also covers the East Malaysian state of Sarawak where more than a dozen rainfall stations in the state and their temporal patterns are programmed into the software.

















detention basin Phone 6012-710-2620










https://www.youtube.com/watch?v=tLfFt4KgJVE




Sunday, October 11, 2015

The design of detention basin using the first and second editions of MSMA

This paper investigates the design of detention basin using the first and second editions of MSMA or the Manual Saliran Mesra Alam (the Urban Stormwater Management Manual for Malaysia) published by the Department of Irrigation and Drainage Malaysia (D.I.D). The computation is done using the MSMAware which is a drainage design software for MSMA developed by Ir. Dr. Quek Keng Hong. The software computes: design storm, temporal pattern, Rational Method, Time-Area Method, On-Site Detention (OSD), detention basin and culvert design. The design of detention basin involves the following steps: (1) Computation of design storm of various ARI and durations. (2) Computation of temporal pattern for the design storms. (3) Determination of a loss model. (4) Estimation of inflow hydrographs to the basin using a hydrograph method. (5) Routing of the hydrographs through detention storage. (6) Check that the maximum basin outflow is less than or equal to the permissible major/minor flow. This section covers the major differences in the approach for the above in the first and second editions of MSMA. One of the major differences lies in the formula used to derive the design storm. Overall, the quality of the storm data in the second editon (MSMA2) is better as the new data is more up-to-date. There are now 135 stations in MSMA2 compared to only 35 previously. This case study design a dry detention basin for a catchment located in Air Terjun, Sg Batu, Kuala Lumpur using MSMA1 and MSMA2 as follows: The losses are based on Table 14.4 of MSMA1 and Table 2.6 of MSMA2. For pre-development scenario, a pervious area of 10 mm initial losses and 25 mm/hr continuous losses is assumed. For post-development scenario, an impervious area with 1.5 mm initial losses and continuous loss of 0 mm/hr is assumed. Outlet use box culvert with 90 degree headwall. A low flow pipe system with a capacity of 2 m3/s will bypass the basin and combine with the basin outflow in the downstream floodway. Determine the percentage increase in the peak discharge using MSMA1 and MSMA2. Primary Major Outlet (1) The stage-storage-discharge relationship. (2) After trial and error, 2 box culverts of 1.2 m by 2.1 m with invert at the critical 5 year water levels was adopted. (3) Maximum discharges, water levels and the permissible discharges. (4) The basin inflow and outflow hydrographs for 50 year storm of duration 30 minutes. Secondary Spillway- The embankment level is fixed at the highest water level of the secondary spillway plus a freeboard of 0.3 m. The storm intensity using MSMA2 is up to 1.26 times higher than that using MSMA1. The peak discharges computed using the Time-Area Method in MSMA2 is up to 1.27 times higher than that using MSMA1. The computed basin storage volumes using MSMA1 and MSMA2 are compared. It can be seen that the storage volume using MSMA2 is about 1.3 times higher than that using MSMA1.

The design of On-Site Detention (OSD) using the first and second editions of MSMA

This paper investigates the design of On-Site Detention (OSD) using the first and second editions of MSMA or the Manual Saliran Mesra Alam (the Urban Stormwater Management Manual for Malaysia) published by the Department of Irrigation and Drainage Malaysia (D.I.D). Specifically, it compares the magnitudes of the Permissible Site Discharge (PSD) and Site Storage Requirement (SSR) using (i) the Swinburne’s Method in the first edition of MSMA (MSMA1), (ii) the Approximate Swinburne’s Method in the second edition of MSMA (MSMA2) and (iii) the Exact Swinburne’s Method (ESM). The computation is done using the MSMAware which is a drainage design software for MSMA. The software computes: design storm, temporal pattern, Rational Method, Time-Area Method, On-Site Detention (OSD), detention basin and culvert design. Software is developed by Ir. Dr. Quek Keng Hong. The PSD and SSR are computed for an industrial and a low density residential development in Kuala Lumpur as follows: (1) Using the Swinburne’s Method in MSMA1 where a set of formulas for PSD and SSR are used to compute their values. (2) Using the Approximate Swinburne’s Method in MSMA2 where a set of approximation tables and figures are used to determine the PSD and SSR values. (3) Using the rainfall and discharge data from MSMA2, but instead of computing the PSD and SSR using the Approximate Swinburne’s Method in MSMA2, the formulas from the Swinburne’s Method in MSMA1 are used ie, the Exact Swinburne’s Method (ESM). In the first edition of MSMA, 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 is basically site-based, but considers the position of a site within the catchment. The peak flow time of concentration from the top of the catchment to the development site, tcs, is compared to the total time of concentration for the catchment, tc. The PSD varies with this ratio and may be less than or greater than the peak pre-development site discharge depending on the position of the site within the catchment. The result shows that for industrial land-use in Kuala Lumpur, the Site Storage Requirement (SSR) using MSMA2 is 2.35 times the MSMA1 estimate. For low density residential land-use in Kuala Lumpur, the SSR using MSMA (2011) is 2.17 times the MSMA (2000) estimate. The difference is due to the use of approximation tables and figures in the Approximate Swinburne’s Method in MSMA (2011), which gives more conservative estimates of the SSR. In conclusion, the ESM Method applies the storm and discharge data in MSMA (2011), but gives lower estimate of SSR than the Approximate Swinburne’s Method in MSMA (2011) because it uses formulas to calculate the SSR values instead of approximation tables. It also takes into account the decrease in surface runoff for lands with higher infiltration rate, through the coefficient of runoff in the Rational Formula.

The changes in the design storms and temporal patterns between the first and second editions of MSMA

This paper investigates the changes in the design storms and temporal patterns between the first and second editions of MSMA or the Manual Saliran Mesra Alam (the Urban Stormwater Management Manual for Malaysia). MSMA is published by the Department of Irrigation and Drainage Malaysia (D.I.D). MSMAware is a drainage design software for MSMA. The software computes: design storm, temporal pattern, Rational Method, Time-Area Method, On-Site Detention (OSD), detention basin and culvert design. Software is developed by Ir. Dr. Quek Keng Hong. The design storms are computed using the Intensity-duration-frequency (IDF) formulas from the first and second editions of MSMA for a study catchment in Kuala Lumpur and the results compared. The objective is to determine the changes in design rainfall intensities between the first and second editions of MSMA. For durations of between 15 to 700 min, the IDF estimates using the first edition of MSMA (MSMA1) were mostly higher than those estimated using the second edition (MSMA2). In the study, out of 14 stations, 10 of them (or 71%) were higher than the first edition curve, while the remaining 4 stations (or 29%) were lower than the first edition estimates. It is concluded that the design storms estimated based on the second edition for Kuala Lumpur can be up to about 26% higher than the first edition for duration below 700 minutes, for 71% of the stations. Overall, the quality of the storm data in the second edition of MSMA is better as the new data is more up-to-date. The IDF data in the second edition covers longer storm durations from 5 minutes to 72 hours, and the lower range ARI of 0.5 to 12 months. There are now 135 stations in the second edition compared to only 35 previously. No IDF data is provided for East Malaysian states of Sabah and Sarawak. The changes in the IDF data is expected to change the magnitudes of design storm. In the second edition, the formula for computing the IDF data has changed from a polynomial formula to an empirical equation. The storm intensities have changed due to the changes in the formula used. In the first edition, the data used were up to about 1983 or 1990. For instance, the data used for the Federal Territory was only up to 1983 in MSMA1. However, in the second edition, the data used were more up-to-date. The temporal patterns for 15, 30, 60, 180 and 360 minute durations for the second edition of MSMA are generally lower than those for the first edition for the first one-third duration but rise above the latter for the remainder. Areal reduction factor (ARF) is given in the first edition of MSMA but not in the second edition. It is recommended that the procedure given in the first edition of MSMA should be applied for the second edition to account for the catchment averaging effect of point precipitation.

MSMAware is a drainage design software

MSMAware is a drainage design software for MSMA- the "Manual Saliran Mesra Alam Malaysia" or the "Urban Stormwater Management Manual for Malaysia" published by the Department of Irrigation and Drainage Malaysia (D.I.D). The software computes: design storm, temporal pattern, Rational Method, Time-Area Method, On-Site Detention (OSD), detention basin and culvert design. Software is developed by Ir. Dr. Quek Keng Hong.