South-East Asia’s coastal cities brace for Waterworld

Construction News

Bangkok – Thinking of buying a condominium in one of the hospitable, thriving capitals of sunny South-East Asia? You might check out their flood prevention plans beforehand.

south-east asias coastal cities brace for waterworldWhile the debate over global warming contines, South-East Asia‘s coastal capitals have been facing the reality of extreme weather and its soggy companion, water.

In 2007, flooding in Jakarta inundated much of Indonesia‘s capital, killing 57 people, displacing 450,000 and causing an estimated 695 million dollars in damage.

Tropical storm Ketsana dumped record rainfall on Manila in September 2009. It submerged 80 per cent of the metropolis, killed about 400 and displaced up to 300,000 people.

Last month, Bangkok just missed a potentially lethal combination of a swollen Chao Phraya River, high tides in the Gulf of Thailand and heavy rain. It didn’t rain.

They were just lucky,’ said Smith Dharmasaroja, a Thai meteorologist. ‘If there had been heavy rain, the whole city would have been flooded.’

Even the efficient city-state of Singapore has had its water woes.

The shopping area of Orchard Road was flooded in June after unusually heavy rainfall, causing millions of dollars of damage to businesses and some red faces among city Mandarins.

‘When we get extraordinary rainfall like we had recently, no amount of engineering can prevent flooding,’ Minister Mentor Lee Kuan Yew said.

If even Singapore can’t cope with abnormal weather, what hope for the rest of the region, especially in the context of potentially rising sea levels?

But the recent disasters have provided ample incentive for the region’s coastal cities to make preparations for a watery future with or without global warming.

Bangkok Governor Sukhumbhand Paribatra this month announced plans to spend 533 million dollars to construct four giant drainage tunnels under the city to combat its perennial flooding problems.

The tunnels, 5 metres wide and up to 13.5 kilometres long, promise to more than double the city’s current drainage capacity when completed in five years.

‘This year’s rainy season has made it obvious that we need the tunnels,’ Sukhumbhand said. Since the last devastating floods of 1995, the city has also built a 72-kilometre-long embankment along the Chao Phraya to keep the river waters out.

Singapore has spent 176 million dollars on a 350-metre-long dam to create the first freshwater reservoir in the heart of the city, which opened in November 2008.

The catchment area of 10,000 hectares, one-sixth the size of Singapore, helps to keep seawater out and to control floods.

Jakarta in 2008 started dredging the city’s 13 rivers and expanding its canal network with the target of reducing floods by 40 per cent by 2011 and 75 per cent by 2016. In January, it completed the 23.5-kilometre Eastern Flood Canal.

Ho Chi Minh City has started construction of a 33-kilometre-long dyke and sluice system to keep sea water from inundating the city. The project will cost an estimated 650 million dollars.

Manila, which sits in the pathway of Pacific typhoons and is deemed one of the most vulnerable cities to storm surges, has done remarkably little to prepare for the next deluge despite a flurry of recommendations.

Few, if any, objective experts or knowledgeable observers believe that the Philippine government is capable of handling or mitigating any major disaster that impacts on Manila,’ said a recent report by Pacific Strategies and Assessments, a business risk consultant.

One immediate challenge all these coastal cities share is land subsidence, caused by excessive use of groundwater and overbuilding; in other words, a lack of law enforcement and zoning.

Jakarta sank about 1.5 metres over the past 20 years; parts of Manila are sinking at 3 to 17 centimetres per annum and Bangkok, whose subsidence peaked at 10 centimetres a year in the 1990s, is expected to sink between 5 and 30 centimetres by 2050.

A recent report compiled by the World Bank/Asia Development Bank estimated that 70 per cent of the flood damage to Bangkok between now and 2050 could be blamed on land subsidence.

Most of the groundwater tapping is done by factories in provinces surrounding the city, who prefer free water to paying for government supplies.

‘It’s an example of how an individual’s rational behaviour can lead to a social impact which is quite detrimental,’ said Jan Bojö, a World Bank environment expert.

The report estimates in case of a severe Bangkok flood by the year 2050, land subsidence alone could cause 3 billion dollars in damage.


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