19 June 2013

Protecting from rising seas: a role for natural shores?

For the first time, Singapore has started looking at coastal works specifically to protect from rising seas. Hopefully, this will also be an opportunity to incorporate natural regeneration in artificial protective structures. As well as the protection of existing natural shores as a continual source of marine life ‘babies’ and plant seeds and seedlings.
Mangroves settling naturally on an artificial seawall at Pulau Hantu.
The Building and Construction Authority (BCA), which is in charge of protecting the island nation's coasts, last month called a tender for a coastal adaptation study - the most extensive one done here yet - to come up with a framework to keep low-lying areas safe.

The Building and Construction Authority also wants a list of adaptation options, new design-and-maintenance guidelines, an instrumentation and monitoring programme, and suggestions for a coastal flood insurance system. And it wants contractors - who must have technical and engineering know-how - to work with research institutions that have at least a decade of experience and research data in Singapore coastal and biodiversity work.
Read more in the full article Singapore takes first steps on plan to protect its coasts, Study to include dealing with rising sea levels and saving low-lying areas by Grace Chua Straits Times 19 Jun 13

More about Singapore and rising seas
In Oct 2011, for the first time, it was mentioned that Singapore "will need to raise minimum levels for land reclamation by at least 1m to create an adequate buffer against a potential rise in sea level". This, according to the Ministry of Environment and Water Resources (MEWR).

In Mar 2010, a Singapore study revealed that sea levels could rise by between 24 and 65cm by 2100. At that time, the Ministry said existing regulations were sufficient. These included a requirement since the early 1990's for reclaimed land to be built at a height of 125cm above the highest measured tidal level, as a buffer against rising sea levels.

Why are rising sea levels a concern for Singapore?

Rising sea levels could flood key economic areas which lie less than 2m above sea level. These include Changi airport, the Central Business District, Marina Bay, Jurong Island, the Western coastline where our container and shipping facilities are located and Semakau Landfill. High value areas like Sentosa Cove are also at risk.

Storm surge floods
With rising seas, key petrochemical, shipping and shipbuilding facilities on the West Coast could be vulnerable to wave attacks because of seasonal thunderstorms called 'the Sumatras'. These can uproot tall trees and cause a storm surge of high water.
Sumatras building up over Jurong Island.
In Sep 2012,  I learnt from Prof Teh Tiong Sa about the potential impact of storm surge on the artificial Seringat-Kias, and natural shores of Lazarus and St. John's Island.
Prof Teh also shared about the extensive work being done to find out more about how rising seas will affect Singapore. But as he emphasises, the eventual outcome is a matter how how we determine baselines, and that designing in preparation for climate change can help us cope with eventual changes. But still, some of the possible outcomes can seem alarming.

Salt intrusion into drinking water supplies
Rising seas will also threaten Singapore's coastal reservoirs, such as Kranji, Sarimbun and Seletar. Salt water entering these reservoirs will make the water undrinkable. It can take up to two years for the sea water to be flushed out completely by rainwater.

Rising seas will worsen the already serious erosion problems seen on many parts of Singapore's coastline.
Serious erosion along the East Coast Park shoreline.

More flooding
Besides rising seas, climate change may also force Singapore to cope with higher rainfall. This month, the expert panel examining Singapore's flood protection measures said that "rainfall patterns seem to have changed" with "evidence that the maximum intensities have increased over the past 30 years."

More about the possible impact of rising seas on Singapore in this old post.

Can artificial shores support natural marine life?
Yes! This stunning reefscape is growing on  artificial pontoons at Marina Keppel Bay and can be easily seen even from above water!
Various sea fans
Our artificial seawalls can also provide places for reefs to settle and grow naturally. The most amazing example of this is of course the reef at Tanah Merah Ferry Terminal. Kok Sheng was the one who first shared a closer look a them. Among the hard corals seen here are large colonies of delicate branching and plate-forming corals. As well as less common species such as Lettuce coral (Pavona sp.), Horn coral (Hydnophora sp.) and even rarer species such as Cabbage coral (Trachyphyllia geoffroyi).
Photo by Loh Kok Sheng on his blog.
Even mangroves can settle naturally on our artificial seawalls! This has happened at Pulau Hantu with a wide variety of mangrove species settling all on their own without anyone planting them there. This includes the less common Bakau pasir (Rhizophora stylosa)! These trees are tall and very healthy, producing lots of propagules that can grow up to become more mangrove trees! More in this post and more photos in this set.
Mangrove trees growing on the artificial seawall
Pulau Hantu have grown so tall! In Mar 2013
While lush seagrasses have settled in the sandy lagoon behind the artificial seawalls at Tanah Merah Ferry Terminal! This is the larger of the two patches of Smooth ribbon seagrasses (Cymodocea rotundata). So far, the only other places where this species of seagrass is found are Chek Jawa and Cyrene Reef.
More about amazing  marine life that we have already encountered on Singapore's artificial shores in this old post.

Natural protection!
Not only are these marine ecosystems beautiful, but they can also play a role in protecting the shores from coastal flooding and rising seas. Hopefully, BCA will include these aspects into their plans for coastal protection works

Need to protect the mothers!
For natural regeneration to take place, it is important to protect existing natural sites as a continual source of marine life ‘babies’ and plant seeds and seedlings.

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