THE National Parks Board (NParks) is conducting an in-depth study into the extent and causes of soil erosion in the Sungei Buloh Wetland Reserve.
The area being studied is a 2km stretch of the Kranji coastline, where mangrove roots are appearing more exposed than usual.
In the 'worst case scenario', up to $25 million may be needed for extensive works to shore up the coast, though the actual cost will be known only after the survey and redevelopment proposal are done by next September.
NParks conservation director Wong Tuan Wah stressed that the erosion has not reached 'alarming' levels yet, and that the study is a pre-emptive move.He said: 'The approach is to identify the issues now and manage them ahead of time, instead of waiting for permanent damage to be done.'
Dr Ho Hua Chew, who chairs the Nature Society's conservation committee, suggested that boats could be churning up waters, washing away the soil around the roots of the mangrove trees.
He said it is a good idea to do the study to identify the problems in the area.
Associate Professor David Higgitt from the National University of Singapore's Department of Geography said that signs of coastal erosion would include sediment around the roots of the mangrove trees being washed out.
A trained observer would notice this, he said.
A guide who accompanied a team from The Straits Times to Sungei Buloh last Friday pointed out instances of exposed roots.
The team also saw a toppled tree among the mangroves.
NParks was unable to confirm whether the tree fell over because of weakened roots or from some other cause, such as being struck by lightning.
Ms Ng Sock Ling, the assistant director of Sungei Buloh Wetland Reserve, said that the signs of erosion may not be apparent to the casual visitor.
Two park regulars, Mr Spencer Chew and Mr Peter Tan, both engineers in their 50s, said they had not noticed that erosion was a problem there.
Sungei Buloh was gazetted as a nature reserve in 2002, after years of lobbying by green groups here.
The 130ha site was also designated an Asean Heritage Park in 2003.
The study on soil erosion is part of the Sungei Buloh Master Plan, announced earlier this year to strengthen biodiversity conservation in the area.
A fallen mangrove tree at the Sungei Buloh Wetland Reserve where signs of soil erosion have been reported.
Soil erosion has exposed these mangrove tree roots (top) at Sungei Buloh, compared to well-embedded roots (bottom) at the nature reserve. -- ST PHOTOS: KEVIN LEONG