Singapore has been hit by floods in an otherwise thought dry month of June. This is not the usual period where heavy rainfall is expected. The unusual rainfall patterns around the world is causing many of the drainage systems in cities to overflow and systems are unable to cope, thus causing damages to properties and worse, life lost. Rainfall is a natural phenomenon and water needs time to flow out to the sea or to low lying ground. It's a matter of simple physics. What engineers do is to create channels, canals, drains to transport the large amount of water from one place to another, usually to reservoirs or to the sea. These are only man-made engineering measures, which require considerable time and resources to construct. Land has to be reserved for such massive structures, and a balance usually has to be reached for the use of the land.
Unfortunately, our prediction of rainfall and modelling of stormwater flows is dependent on statistics and predictions can become haywired because of changing weather patterns. How to convince governments to spend resources, set aside land otherwise used for businesses/population, for sufficient drainage systems when it is just a risk which is not guaranteed? No modelling systems is accurate, because the inputs are not assurance of the future occurence, just a possibility. After all, it is risk mitigation.
Extracted from Channel News Asia
Govt to bring forward plans to improve drainage in flood-prone areas
By Mustafa Shafawi and Joanne Chan
Posted: 19 July 2010 1434 hrs
SINGAPORE: The government will bring forward plans to improve drainage in major canals and drains in flood-prone areas. There will also be an urgent review of the Stamford Canal which overflowed and caused the June 16 and July 17 floods in Orchard Road. With Singapore hit by three floods in just a month, the issue dominated Parliament for a good half an hour on Monday.
10 Members of Parliament (MPs) wanted to know the cause of the floods, and what the government was doing to prevent a repeat. "In one month, there are three floods in Orchard Road and other parts of Singapore. Do you think that this could have been prevented and why do you think so," questioned Lee Bee Wah, MP for Ang Mo Kio GRC. "If these areas identified are the same as those identified in previous years... then why is the drainage of those existing flood-prone areas not rectified in the first placed," asked Penny Low, MP for Pasir Ris-Punggol GRC.
In reply to the parliamentary questions, the Minister for the Environment and Water Resources, Dr Yaacob Ibrahim said there are plans to implement drainage improvements to several major canals and drains. Dr Yaacob said the tender for improvement to Geylang River closed in June. Tenders for improvements to Bukit Timah First Diversion Canal and the downstream stretch of Rochor Canal1 will be called in the next three months. Tenders for the upgrading of major drains along Thomson Road and MacPherson Road will be also called by the end of the year. Works to improve the drainage system in the flood-prone areas of Little India will start in the next few months.
Dr Yaacob said wherever possible, PUB will bring forward the start of these works and expedite their completion. Dr Yaacob Ibrahim also said Orchard Road, which flooded just last Saturday, is a new hotspot. He said an urgent review of the Stamford Canal is being undertaken. "We need to review the design of Stamford Canal and its adequacy altogether. I think the last July 17 storm caused us to be very concerned that this a major canal - diverting water all the way to the sea - is flooded. We need to take a serious view of what needs to be done," said Dr Yaacob.
Dr Yaacob said the incidence of flash floods is a challenge faced by cities around the world. Recently, devastating floods in France, China and Japan inflicted significant damage and loss of lives. As an island in the tropics, Singapore is especially prone to intense rain storms. He said Singapore has seen the occurrence of three intense rainfall events over the past month, caused by Sumatra squalls and the influence of Typhoon Conson, and aggravated by the prevailing La Nina conditions. Dr Yaacob said climate change could add a new level of complexity to this. He said he empathised with the frustration and anxiety of those affected by the recent floods. Dr Yaacob said PUB officers will continue to hold dialogues with affected residents and businesses and advise on possible improvement measures that they can take. He said improvements will also be made to the alert system to provide early warning of possible floods to the public. PUB will also be increasing the number of water level sensors installed in canals from 32 to 150 by next year. Currently, when sensors installed in canals are activated by rising water levels, an SMS alert is sent to warn businesses in the vicinity.
Dr Yaacob said his ministry is studying if this system can be extended to members of public in low-lying areas, so that they too will have sufficient time to respond to a possible flood. The minister said although it might not be realistic to expect Singapore to be completely flood-free, his ministry will work with the relevant agencies to carry out a systematic review of all major drainage systems and their design parameters, as a priority. The review is expected to take several months, and all possible interventions will be considered within the constraints of cost effectiveness and competing uses for limited land in Singapore.
The government has invested some S$2 billion to upgrade Singapore's drainage infrastructure in the last 30 years. As a result, flood-prone areas have been reduced from 3,200 hectares in the 1970s to a total of 66 hectares today. - CNA/vm/ls
No comments:
Post a Comment