FLOOD ALLEVIATION SCHEMES

[Mr Speaker in the Chair]

Mr Chin Harn Tong asked the Minister for the Environment (a) when his Ministry's flood alleviation schemes will fully achieve their target and (b) what are the areas still prone to flooding caused by rain and/or high tide.

The Minister for the Environment (Dr Ahmad Mattar): Mr Speaker, Sir, flooding is no longer a serious problem in Singapore. It is now less frequent and less extensive. The flood prone area in Sin- gapore has been reduced from some 3,200 hectares in the 1970s to 354 hectares now.

Fifteen hectares in the Bukit Timah area are still flood prone, compared with 142 hectares before the completion of the Phase IIA Diversion Canal in 1990. Bukit Timah Road and Dunearn Road are no longer flooded now. The areas in Bukit Timah that experienced flooding in last December are Adam Road, Eng Neo Avenue, Queens Road, Balmoral Road and Steven Road. The drains at these areas, except that at Adam Road, are now being widened and deepened after the Diversion Canal was completed.

Drainage improvement at Adam Road will be carried out after the Public Works Department has finalised the design details of the Adam Road Interchange Project. This is because the configuration of this project will affect the alignment of the drain. Improvements to the drains at the other areas in Bukit Timah began after the diversion project and will be completed by the end of this year.

Besides Bukit Timah, Sir, other areas that experienced flooding recently are Braddell Road, Newton Circus, Outram Road, Poh Huat Road, Farrer Park and Neo Tiew Road. Flood alleviation measures for these areas will be taken during the current year. These measures include the widening and deepening of Sungei Kallang to receive the drain outflows from Braddell Road and the construction of new outlet drains in the other areas.

Flood alleviation measures will be carried out in 28 other areas over the next five years. By then, the flood prone area in Singapore will reduce to 260 hectares scattered in 21 low-lying areas. Flooding at these areas can be alleviated only when the ground levels are raised through redevelopment.

Mr Chin Harn Tong (Aljunied GRC): Sir, when all these measures have been completed, can the Minister give an assurance that flooding will not recur in these areas?

Dr Ahmad Mattar: Mr Speaker, Sir, I cannot give that assurance.

Mr Chin Harn Tong: Why can't the Minister do it?

Dr Ahmad Mattar: Mr Speaker, Sir, all the schemes that I have outlined just now are flood alleviation schemes and, as the name suggests, they can only alleviate but not eliminate floods.

Sir, if I may explain to the Member. Incidence of flooding in any catchment depends on several factors, chief of which are (1) heavy rainfall and, worse still, if it is continuous heavy rainfall for days on end, like the ones we experienced in December last year; (2) tidal influence; (3) the limited conveyance capacity of the drainage system of the catchment and, in some cases, on the low-lying nature of localised areas in a particular catchment. Of all these factors, unpredictability of weather is something quite beyond my control.

The drainage system of a particular catchment is designed for storms of a certain magnitude and once this capacity is exceeded, the system overflows and flooding occurs. So no drainage system can eliminate flood in a flood prone area. It can only alleviate flood in the area.