Cheap tool may help reveal vulnerable coastal wetlands

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  • New tool is cheaper and has higher resolution and accuracy
  • But scientists are worried it is too sensitive and fragile for local tide conditions
  • Others believe it could help monitor mangrove depletion

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[BANGKOK] Researchers in Singapore have developed a cheap new tool to identify areas vulnerable to sea level rise.
The device uses a method known as a rod surface elevation table, involving a rod drilled through soil down to the base of the mudflat to serve as permanent reference point. A horizontal arm is attached to it that measures the change in distance to the surface through time.
Its main aim is to fill a large data gap in monitoring coastal wetland vulnerability to accelerated sea-level rise — areas like coastal salt-marshes and mangrove forests.
Edward Webb, associate professor of biological science at the National University of Singapore, and lead researcher of the study, says the new method is an improvement over other techniques like airborne imaging because it is cheaper to install and has higher resolution and better accuracy.
In South-East Asia, sea level rise causes increase flooding in big cities like Bangkok and Jakarta, which are not very far above sea level. It also makes the region's shores more susceptible to catastrophic storms and tsunamis.
Shiv Someshwar, director for Climate Policy at the Center on Globalization and Sustainable Development Data, Columbia University, New York, says: "From what I have read of the tool, it's certainly simple, affordable and easy to use. That's all for the good".
"Data collection often becomes unsustainable due to high running costs or the requirement of high technical capacity," he adds. "That'll not be the case here."
Some scientists, however, have reservations about whether the new tool will deliver better results.

Ariya Aruninta, associate professor of landscape architecture at Chulalongkorn University in Thailand, expresses concerns about the tool's efficacy.
"It seems to be too sensitive and too fragile for the existing condition of our [Thailand] seashore tides," she says. "And due to the thick layer of soft muddy beach, the tool may be difficult to install."
Wim J.F. Simons, a research associate at the Delft University of Technology in the Netherlands, says:

"The tools need to stay undamaged in place for a longer period of time. So they need to be protected in some way, and preferably be located in regions that will not be developed in the future".
Simons points out that just as with GPS points, the new tool's benchmark only provides information for its exact location, while it's possible that in nearby coastal regions the local conditions might be different.
But he believes the new tool is ideal for measuring whether wetland areas can keep up with "relative sea-level rise", and how much the sea level is increasing with respect to a local coastal area. 
This would be especially useful in coastal areas of Thailand, where mangrove forests provide an important buffer along the nation's wetlands, Simons says.

If the sea level rises too quickly, a mangrove forest eventually dies, after being submerged between tides, leaving the communities bordering mangroves more vulnerable.
He also believes the new tool will be useful for monitoring manmade damage to wetlands and coastal areas caused by urbanisation, aquaculture and nutrient loading or excessive amount of nutrients (mostly nitrogen and phosphorus) from agriculture.
Link to full article in Nature Climate Change
This article has been produced by SciDev.Net's South-East Asia & Pacific desk.


Nature Climate Change doi:10.1038/nclimate1756 (2013)