MSMAware Computation

General Information


Location = Kuala Lumpur

2P24  = 100

Type of Pre-development = Park Lawns and Meadows

Type of Post-development = Semi D houses (low density)

Area = 547 m²

Impervious = 43.14 % from total area

Pervious = 56.86 % from total area

Time constant, tc = 30 minutes

Time constant, tcs = 25 minutes

OSD design = Above-ground



Step 1: Start MSMAware. Select ‘One Site Detention’ tab.


Step 2:- Select MSMA1 and select “General” tab.


Step 3:-Enter the project time value for ‘tc’ and ‘tcs. Make sure the time is in ‘minutes’ units.


Step 4: Choose the design ARI for project storage.


Step 5: Enter the ‘impervious area’ and ‘pervious area’ for ‘pre’ and ‘post’ data. Make sure that the area is in ‘meter squared’ unit.


Step 6: Select the earth cover categories for ‘Pre’ and ‘Post’ development. If the C value is fixed, then choose true. Select ‘False’ if the C value is not fix value.


Step 7: Select the general type for the storage development.


Step 8: Select the type for ‘Town’ and ‘Location’ of the site project. Insert the value for 2P24.


Step 9: Select ‘Outlets’ tab.


Step 10: Enter the value of ‘cd’ and ‘ho’ for primary outlet – orifice.


Step 11: Enter the value of ‘head over weir’, ‘free board’ and ‘Cbcw’ for ‘secondary outlet-weir’.


Step 12: Click “Run” button.


Step 13: The result will be shown in the ‘calculation tab’. The value of orifice size and weir size will automatically calculate.


Step 14: Click ‘MSMA1’ button to get the full report for MSMA1


Step 15: Full report On Site Detention is shown as bellow.



Editor :- Dilah – 26 March 14



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