by Piyaporn Hawiset
20 November 2002
James Gordon reported that fears were being expressed by both fishing people and scientists that hydro-electricity dams on the Mekong threatened its very existence as a river. Since the early 1990s, a series of hydro-electricity dams have been built or were in various stages of construction along the upper reaches of the Mekong north of Yunnan's border with Laos. The purpose of these dams is to provide power for industry and the country's economic and political elite. According to Dr Tyson Royal Roberts, a prominent fish ecologist and associate with the Smithsonian Tropical Research Institute in the US, however, the actual effect of them is 'fluvicidal'. That is, they would kill the river as has happened elsewhere.
The second conference of the fishing peoples of the Mekong River Basin, which was convened by the non-government organisation Towards Ecological Recovery and Regional Alliance (TERRA) and held in Phnom Penh at the end of April 2002, agreed with Doctor Roberts' assessment that the dam-building programme was dangerous to the fishing industry and had already damaged fish populations. The conference issued a declaration noting the impact of the dams with 'special concern', and also cited deforestation, agricultural chemicals, pollution from factories and destructive fishing methods (including the use of explosives) as other dangers to the river.
A further five-day conference was held in Thailand in November. Organised by TERRA, the Australian Mekong Research Centre (AMRC) and other NGOs, the aim was to promote debate and co-operation among the people of Yunnan and South East Asia whose lives were now directly affected by the health of the river and who, irrespective of political mandate, do make decisions about it.
The Mekong rises in the mountains above Yunnan. It normally collects 50 per cent of its silt in the steep country north of Yunnan's border with Laos. This means 50 per cent of all the silt that comes from the mountainous parts of the Mekong basin, in China, Myanmar, Laos, Thailand, Vietnam and Cambodia, and is distributed on the floodplains, including the Mekong Delta in Cambodia and Vietnam. The water that carries this silt is 16 to 20 per cent of all the water that enters the Delta.
One unintended by-product of the dams is that they block the transfer of nutrient silt to the rice fields and fisheries of the floodplains. The transfer of silt out of the highlands and into the floodplains can be seen as the transfer of a precious commodity from one country to another. With the coming of big dams, mountainous countries and regions can now block the transport of silt, not to mention water, to lowland countries and regions. This represents a challenge to one of the elementary principles of primary-school geography, namely that it is the silt from the Central Asian highlands which forms the delta of the Mekong.
Instead this silt now fills the spaces behind the dam walls that ideally would be occupied by water. This can drastically shorten the estimated life span of some very big dams to less than 20 years or less than their intended lifespan and amortization period, meaning they can never pay for themselves. The silt also often damages the dams' generating turbines.
Even before they silt up, dams may have to be decommissioned ahead of schedule, depending on the respective importance given to the new industry (electricity) and to the traditional ones (rice and fish). But there appears to be no plan in place for what to do with the very large objects that will remain, the dam walls. One dam planned on the mainstream of the Mekong is 300 metres high, very much taller than the largest pyramid in Egypt.
The residual materials of decommissioned dams will also, like nuclear waste, be a problem for the future. At present there is apparently no plan to mine silt from behind dams walls in the higher reaches of the Mekong and on-sell it downstream. At the moment, the silt is regarded as infertile, as it is laid down in deep water that contains very little oxygen.
Future concerns
"The natural fisheries of the Mekong River Basin are rapidly declining," delegates to the Phnom Penh conference noted. "We are catching smaller amounts of fish, we must work harder and longer to them, and the fish we do catch are smaller than 10 to 20 years ago."
The flow of water in the Mekong can now be controlled to some degree, as it has to be to provide electricity at the times it is needed in houses, offices and factories. The electricity has to be produced at the moment it is needed, for example for air-conditioning on a very hot day, as it cannot be stored. It has been said, in favour of the dams, that they can also be used to mitigate dangerous flooding on the Mekong, and to provide water in the dry season for irrigation and navigation when the river is low.
The natural maximum flood and minimum flow of the Mekong are, however, needed for (for example) the rise and fall of the Great Lake of Cambodia, this being crucial to the fish populations and the fishing industry based on them. The Cambodian Government, the Mekong River Commission and other agencies have devoted much effort to helping Cambodians work in harmony with this natural regime. If what has been called 'regulation' (control of the river's flow) is instituted, farmers and fishing people in Cambodia may try to compensate by restoring natural flood levels with pipes and canals, which would be financially disastrous.
Dr Roberts said the changes due to hydro-electricity dams would be the end of the river as a river. The characteristics of a river produced by its own power - 'natural hydropower', in Dr Roberts's words - would be lost in favour of conversion of this power, in generators, to electricity. But it is this natural power which forces bends in the river, forms sandbanks and shapes islands. It causes the pulse of water into the Great Lake and pushes back the ocean at the mouth of the Mekong, cutting salt concentrations in the rice fields of the lower provinces. It is the energy that transports the silt.
The tallest dam (300 metres) planned on the mainstream of the upper Mekong is scheduled to start filling in 2010. The construction of one high dam on the higher reaches of the Mekong, the Manwan, was completed in 1993. At the time of the Phnom Penh conference, information about the effect of this dam on recent flooding of the lower Mekong was unknown. Dr Roberts had asked the Mekong River Commission, but it said it had not been made privy to the information because of the serious negative impacts caused by the dam, whcih were deemed should not be released to the general public.
Because the ability of big dams to control the whole river was not foreseen, and the Mekong Basin is not contained within any one country, decisions about the uses of the Mekong cannot be made by any one government. The Mekong extends beyond any group or commission, and cannot be controlled in the way (for instance) that Vietnam exerts control over the Saigon River.
The fishing delegates to the Phnom Penh conference found themselves asking to what authority they could take their observations about the state of the Mekong. This same question has also been asked by people outside mainland Southeast Asia, including the director of AMRC at Sydney University, Phil Hirsch, and Dr Milton Osborne, in his new book, Mekong. NGOs have referred to 'civil society' and public awareness, as an alternative to governance 'from above' and in response to the vacuum in traditional governmental authority.
When Dr Roberts said at the Phnom Penh conference that the Mekong was right now 'in relatively good condition', he meant relative to what would happen if dam-building on the mountainous parts of the Mekong mainstream continued. Future decisions about the Mekong would probably be made on the basis of pure economics. That is, only if more is lost in rice and fish than is gained in electricity will the dam-building stop.
However, Southeast Asia is part of a world which now places importance on environmental and cultural values. These values are finding increasing expression in the tourist industry. Thus, although "hydro-electricity dams are probably inevitable in South East Asia" (Lonely Planet, Cambodian edition), it may be that environmental and cultural values (via the tourist industry) will have the spin-off effect of helping the rice and fish industries. Blue skies, green fields and jumping fish could have multiple economic effects not easy to calculate.