Coastal and flood risk management in South East Asia - Part 1 Malaysia and Borneo
A collection of interesting, different or strange approaches to manage coastal and flood risks that I stumbled across during a trip though South East Asia.
Flood risk in the floating villages
I started my journey on the east coast of Malaysia, on Borneo Island. It was not long until I was on a boat and got my first chance to see an example of their floating villages. These are entire towns built upon hundreds of piles and jetty structures, on a scale that I was not expecting. But it was their height just above the tide level that immediately stood out. I have found mixed references about the flood risk of these villages, ranging from several comments from our guides that they are 'high enough', to exactly the opposite; that they are only just higher than the sea levels achieved during the common monsoon season - which to me sounds like any extreme events and storm surges would lead to inundation.
Above: The Floating villages of Malaysia
Thankfully the threat of Tropical Cyclones in Malaysia is low, with the local reference to the country as the 'land beneath the wind' actually a reference to its position south of the typhoon belt. With the main flood risk due to heavy monsoon rainfall the position of these villages may actually be safer that the inland valleys. However they remain at an extremely high risk of tsunami, with the 2004 Asian tsunami resulting in huge losses of life and property.*
Thinking further ahead, I wonder how resilient these villages will be to future changes in sea level? Whilst one wooden structure may be easier to raise than a single slab-on-ground house, the scale of these villages around the country must surely pose a challenge for the future.
Erosion risk management
As a nation of islands, I was in a coastal engineer’s paradise. I heard reference that around 30% of Malaysia’s shorelines are eroding, and as typically the case this erosion was most displayed adjacent to hard structures and areas with poor planning.
Above: Not a bad view, but perhaps not during a storm
The major harbours and jetties of the larger towns were all as expected: rock lined or with grouted masonry, and in good condition. But as I went further onto the outer islands it was clear that finding suitable rock was a problem. Coastal villages were either unprotected, some had seawalls made of concrete blocks or rubble, and some simply made do with sand-filled sacks which are a far cry from the GSC revetments seen in Australia.
Above: Right: A seawall made of concrete blocks/slabs. Left: Sand bags around an eroding pier
I was happy to see that hard defences were not the only way of managing the coast. As demonstrated on Sipadan Island (one of the best natural dive sites in the world, and now a nature reserve) they have used a change in policy to remove several resorts that were once based within the coastal zone. Now only a handful of structures remain, and they appear to be their last legs...literally. When I was asked if a small seawall would be effective at defending these remaining structures I was reluctant to agree. Why not get rid of them altogether? No building = no erosion problems, right? Of course how, or if, we should protect natural systems against erosion is somewhat of a trickier issue.
Above: I think I would walk away from this one...
I have had a great time on the Borneo Island, and am now off to see the coastlines and floodplains of Vietnam.
* The best (but not most recent) resource I found on flood risk is by Ngai Weng Chan: http://www.eria.org/Chapter_14.pdf
If anyone knows of other discussions, resources or projects in the area please get in touch as I would be interested in finding out more.