Wildlife loses out in plan to save streams

Jenny Quinton's two children once swam and paddled in the Wang Tong stream, a leafy backwater tucked away behind bustling Silvermine Bay.

Today, their splash pool has been transformed into a concrete storm drain, with it having gone the aquatic life and vegetation bordering the meandering stream, whose tranquillity attracted people to set up home nearby.

The scenic setting has been destroyed by a $10 million river training project, one of hundreds of schemes under the Rural Planning and Improvement Strategy (RPIS) minor works programme which spent $280 million last year on improvements in the New Territories and outlying islands.

Ms Quinton is not impressed. 'It is going to be so ugly. The river is completely and utterly disgusting,' she said.

Arguments over Wang Tong caused a stir in the Mui Wo community late last year, but it was not an isolated botched job. In 1996 the Government concreted over - or channelised in engineering jargon - 38 sections of streams and rivers throughout the territory.

Wang Tong served to highlight increasing concerns by environmentalists, landscape engineers and ecologists that channelisation was ruining some of Hong Kong's most ecologically diverse habitats.

Of course, the Government was not spending millions of taxpayers' dollars for the fun of slathering concrete over pristine watercourses. The Home Affairs Department, which runs the RPIS, says river training is a necessary flood control measure.

Indeed, development of low-lying areas in the New Territories and outlying islands has increased the likelihood of flooding because wetlands, which absorb heavy rain, have been filled in.

After requests from residents for flood prevention measures, at least 15 streams are earmarked for improvements this year, at a cost of about $50 million.

According to engineers the easiest and most effective method of improving water flow after heavy rain is to create a U-shaped or trapezoidal channel, flatten the river bed and cover it in concrete.

But this solution considers the flooding problem only from an engineering perspective and fails to take account of other factors, such as the wildlife value of a stream and its scenic setting.

Ecologist and affiliate member of the Hong Kong Institution of Engineers, Janet Forbes, says traditional concrete channels can have a 'devastating ecological impact'.

'Where the diversity of habitat is ironed out by the creation of a traditional engineered, trapezoidal channel with uniform banks, only the most adaptable organisms will survive,' she said.

Opposition to heavy-handed engineering has been slow to voice its concerns partly because the ecological importance of the territory's streams has only recently been recognised.

Research by freshwater stream expert, Dr David Dudgeon, has revealed a wealth of insects, plants and amphibians whose lives are woven together in the complex web of river ecology.

So rich are some of Hong Kong's unpolluted streams that scientists have yet to identify all the species which delve deep into the muddy bed.

Romer's tree frog, the Hong Kong newt and cascade frog are some of the unique creatures that make their home in freshwater streams.

Tai Ho and Tung Chung stream in north Lantau harbour 53 species - more than half of the freshwater fish recorded in the territory - including the rare ayu, which is found nowhere else.

Lam Tsuen river supported more than 120 species of bottom dwellers, before it was channelised in 1984.

The myriad aquatic creatures inhabiting the stream in turn attracted visiting birds and animals, such as bats to feed on the river's rich pickings.

The effects of channelisation were dramatic, says Dr Dudgeon who is reader in the Department of Ecology and Biodiversity at Hong Kong University.

'That whole community has gone,' he said.

Several species of fish, crabs and shrimps migrate upriver to spawn - including the ayu, a relative of the salmon. But in many cases where weirs, dams and culverts have been created, their return route is blocked.

Culverts created at the mouth of Tung Chung stream - due to be channelised as part of a new town development - have effectively barred fish from returning and breeding.

Dr Dudgeon said the pollution in lowland streams was no justification for channelisation, particularly since greater government controls on waste had improved water quality in recent years.

'Channelisation is like the final nail in the coffin,' he said.

No part of the territory is immune. Green Lantau Association vice-chairman Fabian Pedrazzini says the island's major streams are targeted for 'stream course improvement'.

Apart from Wang Tong which, says Mr Pedrazzini, has been 'irrevocably destroyed' by channelisation, two other streams in the Mui Wo area have been earmarked.

At Pui O, on the south side, there are plans to carry out 'a typical river training project' under the RPIS.

Originally the plan was to channelise Lo Wai Hang to improve the flow of water which floods private land during the rainy season.

After environmentalists questioned the necessity of this $1.2 million project in a coastal protection area, the department agreed to scale it down.

However, one section will still be channelised, says Mr Pedrazzini, for no good reason.

'It is just a piece of abandoned land, a coastal protection area, so it is difficult to imagine why they would want to channelise it. Flooding on private land only happens for a very short period once a year,' he said.

Friends of the Earth spokesman Lisa Hopkinson estimates streams are being concreted for floods which may happen once in 2,000 years.

'This is totally incompatible with the design life of the materials being used, planning horizons and public expectations. The result is that they are normally empty for most of the year exposing a lot of ugly concrete,' she said.

'It is just ridiculous engineering overkill. It is a very heavy-handed approach to a reasonably straightforward problem.' Environmentalists also say channelisation fails to address the fundamental causes of flooding - urbanisation of flood plains and soil erosion from deforestation, often the result of hill fires.

The channel creators, which include Drainage Services, Civil Engineering, Territory Development and Home Affairs departments, defend their design as the best and only option available.

Yip Sai-chor, chief engineer at the Civil Engineering Department, which was responsible for Wang Tong stream, said a balance had to be struck between flood control and environmental protection.

Studies of Wang Tong showed a one-in-200-year chance of a flooding bursting the banks, he said.

'It sounds like a very long time, but it could happen any time during the 200 years - it could happen next year. Can we afford to let people's lives and property take that risk ?' The Lantau District Office consulted with the Rural Committee and RPIS watchdog over Wang Tong, so Mr Yip admitted the department was surprised when confronted by angry residents.

Engineers became embroiled in a vociferous argument over Wang Tong with the Rural Committee supporting the channelisation and other, mainly expatriate residents, opposing it and suggesting a more environmentally-friendly solution.

But Mr Yip said the residents' alternative was impractical.

'It is not workable. On both sides of the stream there are houses so there is not a lot of working area we can use.' He concedes engineers should be more aware of environmental concerns but says residents and environmentalists exaggerated the ecological importance of a stream whose lower reaches were already degraded.

'We have to strike a balance between requests of different residents in the area,' he said.

'The local villagers were complaining we didn't do the work fast enough . . . [that] we took too much time to negotiate with other people.' The Home Affairs Department admits channelisation is the least environmentally-friendly method of flood control but says that 'no special species have been endangered by any RPIS minor works'.

In a paper to be presented to the Advisory Council on the Environment today, the department defended RPIS projects which it said were instigated with the support of residents after extensive consultation.

Mr Pedrazzini pointed to Wang Tong as proof the Government's elaborate consultation process did not work.

For many Mui Wo residents the first they knew about the channelisation was when workers began widening the stream and pouring concrete.

Conflict over Wang Tong emerged largely because of contrasting views between indigenous villagers and expatriate residents, a sensitive issue for the Home Affairs Department which told staff handling the dispute to avoid the word 'local' and 'expatriate'.

Environmentalists say they do not dispute the need for flood control, it is the means to that end which requires a major overhaul. Desilting is the preferred option. If banks have to be improved, the stream bed should remain untouched.

Back in the 1980s, Britain began using river corridor surveys to assess the wildlife value of a watercourse before improvements were made.

Such surveys which are used in tandem with river-friendly upgrading techniques, such as improving only one bank, saving meanders and maintaining the river bed, are mandatory for major flood defence projects in Britain.

Unlike Drainage Services Department, which says it is using the river corridor survey technique on river maintenance and dredging projects, RPIS minor works, including channelisations, are exempted from environmental impact assessments.

However, under the new Environmental Impact Ordinance, works to streams and rivers will make assessments mandatory.

The ordinance's technical memorandum, which defines ecological criteria, has yet to be finalised, but Ms Hopkinson said the Government should be following the spirit of the law.

'According to the technical memorandum they should be doing ecological assessment as a matter of course for streams,' she said.

While the law may force the design of more environmentally-friendly solutions, Ms Forbes says the secret to a greener perspective is greater understanding between engineers and ecologists, who she admits don't often see eye to eye.

'If you give these people a hard time they curl up and feel targeted. My approach is to drip-feed them and hope you can make some progress. I am trying to bridge that gap,' she says.