Feng Zengkun Straits Times 24 May 12;
A DIGITAL map of the Marina catchment area will be created by the end of the year to help identify places where flooding may occur.
National water agency PUB announced the $450,000 project yesterday by unveiling the car equipped with laser-scanning technology that will do the job.
Fitted with a rooftop machine that emits laser pulses to collect land height data, the car was put through its paces on a demonstration drive near Newton Circus.
The project started last month and will take about six months to complete.
It will cover some 100km of roads in the catchment's low-lying and flood-prone areas.
The Marina catchment zone makes up a sixth of Singapore and includes Orchard Road and Bukit Timah, which have been hit by floods in recent years.
The map will show the lay of the land to a height accuracy of within 10cm, and the PUB said it can use it to better identify places where water will flow over the ground during storms if the canals and drains are overwhelmed.
Computer models now in use predict only how rainwater flows within drains and canals, and the intensity of rainfall they can handle.
The PUB added that it will work with other agencies such as the Singapore Land Authority to gather land height data on other parts of the catchment area.
It already has information on the ground types in the
area, which affect how much water flows over land instead of seeping into the ground.
In future, the digital map may also be combined with data from other equipment such as rain gauges and water sensors in the canals to give people more advance warning of floods.
A panel of drainage experts appointed by the Government last year to tackle floods had recommended a national map, but the PUB said it will start with the Marina catchment area first.
'This is a pilot project, so we also want to make sure the system works first,' said Mr Tan Tien Ser, who is assistant director of the PUB's catchment and waterways department.
The PUB said it had come up with the 10cm height accuracy requirement by examining floods in the Republic, which run between 5cm and 30cm deep.
The field work will be done mostly at night, when there are fewer vehicles on the road to interfere with the data collection.
In areas where the data is distorted by other vehicles or poor Global Positioning System signals, ground survey crews will be supplied by the contractor to collect the information.