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The RM1.8 billions SMART (Stormwater Management and Road Tunnel) project schedule to be completed and put in use in year 2007.

As according to the project layout, when the tunnel is put on “storm mode”, it is suppose to withheld 3 millions cubic meters of water.

3 millions cubic meters a lot?

This is time we look at the power of the nature. According to the world weather information website, the daily max rainfall for KL is around 32mm. The KL city center is around 4km x 4km, while the outer sketch of KL is around 30km x 30km.

In average, KL city will receive an average of 200mm rainfall (280mm for the wet month and 150mm for the dry month), with average 12 raining days every month. Using the monsoon month scenario, there will be 16mm rain fall for a day. For a 10km x 10km square of KL city center, this is around 1.6 millions cubic meter of rain water. Should the rain dissipate and absorb 50% by various factor, there is still 800,000 cubic meter of water to deal with. By adding the Klang river and Gombak River factor, the 3 millions cubic meter SMART tunnel barely give any relief if KL raining for 3 consecutive days non stop.

Will SMART stop flash flood?
Yes and no. Since KL don’t have a integrated water way, so some flash flood prone area will see no relief on. Only place with drainage channel to SMART will see significant improvement.

What if the same amount of rain pour in KL?
According to news, 35cm of rain is pour in one day, which cause the major flood. Should the similar happen in KL city center(4km x 4km square), there will be 4.8 millions cubic meter of water to handle.

Illustration of 1 cubic meter.
Photo by wikipedia contributor Rama, under CeCILL license. You can download the original photo here