The water resources of the Mekong river catchment area, from China, through Thailand, Cambodia and Laos to Vietnam, are increasingly contested. Governments, companies and banks are driving new investment in roads, dams, diversions, irrigation schemes, navigation facilities, power plants and other emblems of conventional "development." Their plans and interventions pose multiple burdens and risks to the livelihoods of millions of people dependent on wetlands, floodplains, fisheries and aquatic resources.

This report describes the hydrological aspects of a CGIAR project to model the effects of water flows on aquatic resource production in the Mekong Basin. The project was carried out by the International Centre for Living Aquatic Resources Management (ICLARM, Penang, Malaysia) and the International Water Management Institute (IWMI, Colombo, Sri Lanka) in cooperation with the Mekong River Commission (MRC, Phnom Penh, Cambodia) together with other institutes and national and regional agencies working in the riparian countries of Cambodia, Lao PDR, Thailand and Vietnam. The project commenced in January 2000 and finished in December 2000. The land cover analysis for the Tonle Sap area was carried out, and the data on existing and proposed dams were collated, by Dilkushi De Alwis, IWMI, Colombo.

The Mekong is the most controversial river in Southeast Asia, and increasingly the focus of international attention. It flows through 6 counties, China, Myanmar, Laos, Thailand, Cambodia and Viet Nam. The 4 downstream countries have formed the Mekong River Commission to promote sustainable development of the river and many of their people depend on it for their subsistence ? it has possible the largest freshwater fishery in the world, and the Mekong waters support rice agriculture in the delta in Viet Nam (which produces about 40% of that country's food) as well as in Cambodia, Laos and Thailand. China is now building the first large mainstream dam on the river, and has proposals for several more. These dams are likely to affect the downstream countries. Several of the downstream countries also have plans for large scale hydropower and irrigation development which could also impact the river. This book will provide a solid overview of the biophysical environment of the Mekong together with a discussion of the possible impacts, biophysical, economic and social, of some possible development scenarios. It is intended to provide a technical basis which can inform the growing political and conservation debate about the future of the Mekong River, and those who depend on it. It is aimed at river ecologists, geographers, environmentalists and development specialists both in the basin and (especially) outside for whom access to this material is most difficult. This book will be the first comprehensive treatment of the Mekong system. - The first comprehensive overview of all aspects of the Mekong River system - Deals with a regionally critical ecosystem and one under threat - The Mekong supports the world's largest freshwater fishery and provides water underpinning a major regional rice paddy system - Presents the authoritative findings of the Mekong River Commission's research for a wider audience for the first time outside of limited distribution reports

The catchment area of the Mekong River and its tributaries extends from China, through Burma/Myanmar, Thailand, Laos, Cambodia and to Vietnam. The water resources of the Mekong region - from the Irrawaddy and Nu-Salween in the west, across the Chao Phraya to the Lancang-Mekong and Red River in the east- are increasingly contested. Governments, companies, and banks are driving new investments in roads, dams, diversions, irrigation schemes, navigation facilities, power plants and other emblems of conventional 'development'. Their plans and interventions should provide some benefits, but also pose multiple burdens and risks to millions of people dependent on wetlands, floodplains and aquatic resources, in particular, the wild capture fisheries of rivers and lakes. This book examines how large-scale projects are being proposed, justified, and built. How are such projects contested and how do specific governance regimes influence decision making? The book also highlights the emergence of new actors, rights and trade-off debates, and the social and environmental consequences of 'water resources development'. This book shows how diverse, and often antagonistic, ideologies and interests are contesting for legitimacy. It argues that the distribution of decision-making, political, and discursive power influences how the waterscapes of the region will ultimately look and how benefits, costs and risks will be distributed. These issues are crucial for the transformation of waterscapes and the prospects for democratizing water governance in the Mekong region. The book is part of the action-research of the M-POWER (Mekong Program on Water, Environment and Resilience) knowledge network. Published with IFAD, CG|AR Challenge Program on Water & Food, M-POWER, Project ECHEL-EAU and HEINRICH BOLL STIFTUNG

Our understanding of the ecology of running waters has come a long way during the past few years. From being a largely descriptive subject, with a few under tones concerned with such things as fisheries, pollution or control of blackflies, it has evolved into a discipline with hypotheses, such as the River Continuum Concept (Vannote et a/. 1980), and even a book suggesting that it offers opportunity for the testing of ecological theory (Barnes & Minshall 1983). However, perusal of the literature reveals that, although some of the very early studies were concerned with large rivers (references in Hynes 1970), the great mass of the work that has been done on running water has been on streams and small rivers, and information on larger rivers is either on such limited topics as fisheries or plankton, scattered among the journals, or not available to the general limnologist. The only exceptions are a few books in this series of publications, such as those on the Nile (Rz6ska 1976), the Volga (Morduckai Boltovskoi 1979) and the Amazon {Sioli 1984), and the recent compendium by Whitton (1984) on European rivers, among which there are a few that rate as large.