Best of our wild blogs: 23 Mar 12

Announcement: CJ Boardwalk trip on 14th Apr (Sat)
from Adventures with the Naked Hermit Crabs

Spritely
from The annotated budak

Some good news from the 2010 Singapore coral bleaching event
from wild shores of singapore

What’s happening this Saturday
from Raffles Museum News

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Underground reservoir could solve flood problems: expert

Joanne Chan Channel NewsAsia 22 Mar 12;

SINGAPORE: An underground reservoir 100 metres beneath the surface could be one way to solve Singapore's flood problems. This was a suggestion by a prominent engineering expert, Professor Lui Pao Chuen, an adviser to the Underground Master Plan Task Force.

Prof Lui, who shared his thoughts at a talk organised as part of World Water Day, pointed out that Singapore's annual rainfall has been increasing over the past 30 years - from 2000 to 2600 millimetres a year.

Using data from one of the 28 weather stations in Singapore, Prof Lui said the maximum rainfall within an hour has also went up from 90 to 120 millimetres.

Prof Lui noted that Singapore's drainage system is designed to cope with about 80 millimetres of rain in an hour, and said that decisions have to be made now to protect Singapore against increasing rainfall intensity.

With a limit to how much drainage capacity can be increased, taking into account cost and land constraints, other solutions will need to be considered.

One of them is to harvest storm water with shafts and underground tunnels.

Prof Lui said: "Whether the rainfall intensity will actually increase, we don't know. But if it increases, then we've got no choice but to go below with tunnels. And the tunnels must drain into somewhere - it cannot drain into the sea because its below sea level. So it's got to drain into a low-level... which obviously will be some sort of reservoir. And you can use the water."

Shafts and tunnels can be dug into the ground can divert storm water into rock caverns 100 metres beneath the surface. In the event of a drought or when reservoir levels drop, the stored fresh water can be pumped up.

Prof Lui acknowledged that the high cost of excavating deep underground may be too prohibitive. He estimates that it will cost S$1 billion for 20 rock caverns, each with the capacity of half-a-million cubic metres.

But he said the benefits outweigh the cost.

He said: "You can sell the rocks, so it will reduce the cost of excavation. The more capacity you have, the less you need to desalinate. So basically you're comparing the cost of desalination with the cost of this project."

Responding to queries from Channel NewsAsia, national water agency PUB said it will explore the feasibility of underground rock caverns as a possible long-term solution to storing storm water.

-CNA/ac

Underground caverns could solve flooding woes
Esther Ng Today Online 23 Mar 12;

SINGAPORE - Building rock caverns under reservoirs to capture storm water could be a possible solution to flooding and water shortage issues in Singapore.

Such caverns would also reduce the energy spent on desalination, said National University of Singapore (NUS) adjunct professor of engineering Lui Pao Chen.

Speaking at a talk organised by the NUS Global Asia Institute yesterday in conjunction with World Water Day, Prof Lui suggested that such facilities could be realised sooner than was expected.

"The Singapore authorities are very serious … The reason is that we've run out of land," said Prof Lui, who also serves as an adviser to the National Research Foundation. "If rainfall intensity were to increase, we got no choice but to go below with tunnels."

These tunnels could run 100m underground into rock caverns. A possible location would be below the Central Catchment Area.

National water agency PUB is already looking into the idea of using rock caverns as a "solution" to increase the capacity of Singapore's reservoirs, Prof Lui added.

He declined to say how soon the Government would embark on such a project but said that the average cost of building such a facility is S$100 per cubic metre.

The reservoir will have a number of caverns to meet the storage capacity needed, with each cavern envisaged to be between 200,000 and 500,000 cu m.

Going underground is not alien to Singapore. Industrial developer and landlord JTC Corporation is set to finish work on the first phase of the Jurong Rock Caverns between next year and 2014.

Associate Professor Susanto Teng from the Nanyang Technological University's Civil Engineering Department told Today that the properties of the rock will determine the size of the tunnel and cavern.

"Tests will have to be done to see if the rock is stable and can withstand pressure from above. If not, it will have to be strengthened, but this adds to cost," he said.

When contacted, a PUB spokesperson said: "PUB will be exploring the feasibility of underground rock caverns as a possible long-term solution to store storm water."

Meanwhile, the Government is studying global climate models and will expand canal capacity and other drainage projects over the next five years.

In the meantime, it could explore borrowing or renting basement car parks from building owners and retrofitting them into storage tanks should flooding become more frequent, said Associate Professor Liong Shie-Yui from the NUS Civil Engineering Department, who also spoke at the talk.

Storage facilities could be built from the sea bed to sea level to store water and oil or serve as warehouses, while above sea level, these concrete structures can be buildings, suggested Assoc Prof Teng.

Singapore is also exploring building cities underground. Tokyo and Montreal already have retail and commercial spaces below ground, Prof Lui said.

"The volume of the caverns for the underground city will depend on their usage. It can vary between 20,000 to 50,000 cubic metres," he said.

Why not underground reservoirs?
Grace Chua Straits Times 23 Mar 12;

A PROFESSOR of engineering has floated the idea of building reservoirs deep underground, in rock caverns.

Etched out of granite 100m below ground, these caverns can perform triple duty, said Professor Lui Pao Chuen.

Firstly, they can capture the stormwater run-off from urban areas and alleviate flooding. Secondly, as stores of fresh water, they can guard against future droughts. And thirdly, having these freshwater stores means less water will need to be produced through desalination.

Prof Lui was giving a talk at the National University of Singapore (NUS) yesterday, in conjunction with World Water Day. The talk was hosted by NUS' Global Asia Institute, which focuses its research on issues key to Asia's future.

Prof Lui, who retired in 2008 from the Ministry of Defence where he was chief defence scientist for 22 years, is not new to the idea of subterranean facilities: He spearheaded the research on Singapore's underground ammunition facility and is now adviser to the National Research Foundation.

Speaking to mostly academics, he noted that rainfall and rainfall intensity here have increased, but all it would take for Singapore to be hit with a water shortage is two consecutive years of low rainfall.

Rock cavern reservoirs underground can thus catch excess rainfall for use in a dry season; 20 such caverns could hold 10 million cubic m, or 1.67 per cent of the country's annual demand of 597 million cubic m or more.

He suggested that these caverns could be in the north or south of the island - 'it depends where the rocks are' - and that disused quarries would be potential entrances into the earth.

The notion of underground reservoirs has been raised several times over the years. In 1997, national water agency PUB dismissed it as an expensive proposition, saying they would cost as much as 20 times more than surface reservoirs of similar size.

Prof Lui estimates that rock caverns would cost about $100 per cubic m to build. He has two ideas of offsetting the cost.

One is to sell the rocks that are dug out; the other is to sell the hydroelectricity generated from pumping water from ground level into the caverns.

He added that land-scarce Singapore must also consider the value of the land that a surface reservoir would take up.

The four-year-old underground ammunition storage facility in Mandai, for example, freed up land about half the size of Pasir Ris town.

Drainage specialist and chair of the Government-appointed panel on flood prevention, Professor Chan Eng Soon, who was at the lecture, called Prof Lui's idea 'really refreshing, especially when we're not just looking at flood issues, but also at various other grand challenges related to energy and space utilisation'.

Prof Lui, asked how seriously he felt the authorities are taking his idea, said: 'I think they're serious. And the reason is that we're running out of land... When the economy is right, it'll be done.'

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Nest in knickers

Straits Times 23 Mar 12;


An adult olive-backed sunbird (Nectarinia jugularis) checking on one of two young sunbirds in their nest. -- ST PHOTO: SAMUEL HE

An adult olive-backed sunbird (Nectarinia jugularis) checking on one of two young sunbirds in their nest.

The unique home was built inside a pair of briefs that was hung out to dry at an HDB apartment at Kang Ching Road in Jurong.

Flat owner Lim Tinghan, 29, a teacher, said that the eggs hatched on Monday night.

He discovered the nest about two weeks ago and decided to let it be.

He sent pictures of the nest to the Bird Ecology Study Group, a local bird study group which is part of the Nature Society.

[Wildsingapore comment: BESG is operating independently of the Nature Society (Singapore) since 1 Jan 2012]

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