ydropower and developmentof the Lancang-Mekong

River have caused adverse impact onhydrology of the river, especially forthe decreased minimum discharge.After the construction of Manwandam, the mean minimum discharge ofthe Mekong River on Thai-Laoborder declined by 25 percent. Thetrend of the minimum discharge is alsoreduced. The dam operation togetherwith river development project;

November 2004

Downstream Impactsof Hydropower and Development of an International River:

A Case Study of Lancang-Mekong

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Southeast Asia Rivers Network

Map:

Intern

ation

al Riv

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etwork

Upper Mekong Navigation ChannelImprovement Project, have causedunusual rapid water fluctuation. Theseaffect the rich riverine ecosystems,fish, and local livelihoods of fishingcommunities in downstream areas.On Thai-Lao border, it is found thatthe fish catch has declined for 50percent as a result of the waterfluctuation. Hydropower and riverdevelopments have created unprec-edented transboundary environmentalissues. Thus, it is important forriparian countries to immediatelymonitor the impacts and consider therecommendations of the WorldCommission on Dams in decision-making process of the developmentprojects on the Mekong River, onwhich millions depend.

Introduction

The Mekong River, the longest riverin Southeast Asia, feeding millions insix riparian countries from China toBurma, Laos, Thailand, Cambodia,and Vietnam.

Since 1980s, China has played animportant role on Mekong development,under its ‘Go West’ policy and LancangEconomic Belt. The Lancang Eco-nomic Belt policy, comprising ofcascade hydropower dam projects onthe mainstream of the Mekong River,industrial estates, and Upper Mekongnavigation channel improvementproject for large cargo ships to navigatefrom Simao of PRC, to LuangPrabang of Lao PDR.

The Manwan and Dachaoshan damsare already built, Xiaowan andJinghong dams are under construction.

Since China implemented thenavigation channel improvementproject in the 2001 dry season, alongBurmese-Lao border, rapids and reefshave been removed. Along withcanalization at Krai rapids, now 300DWT ships can navigate to the GoldenTriangle town of Chiang Saen.However, the plan to blast Khon PiLuang rapids on Thai-Lao border hasbeen halted due to Thai Cabinetresolution in April 2003. This requeststhe new Environmental ImpactsAssessment and TOR on waterwaybetween Thailand and Laos.

Downstream Impacts

Dam construction and removal ofMekong rapids and shoal mean anunprecedented destruction of thedevelopment history of the MekongRiver. The impacts of the Upper

Mekong development do not exist onlyat the project sites, but across theboundary far downstream.

Decrease of MinimumDischarge

It is widely publicized that only 18percent of the total water flow of theMekong comes from the Lancang.However, in dry season it grows fornearly 45 percent of the average flowas far as Cambodia in April1 . Thus,water flow form the China’s sectionof the Mekong is extremely importantfor the flow of the Mekong on Thai-Lao border.

Recently, it is reported that the

1 International Rivers Network, China’s UpperMekong Dams Endanger Millions Downstream,Briefing Paper 3, October: Berkley, 2002.

à¢×è͹à«ÕèÂÇËÇÒ¹ à¢×è͹áË�§·Õè ó º¹áÁ�¹éíÒ⢧¡íÒÅѧÍÂÙ�ÃÐËÇ�Ò§¡Òá�ÍÊÃ�Ò§ ËÒ¡áÅ�ÇàÊÃç̈ à¢×è͹áË�§¹Õé̈ ÐÁÕ¤ÇÒÁÊÙ§¶Ö§ òùò àÁµÃ

2

Xiaowan Dam under construction

Manwan dam has created an impacton minimum discharge of the Mekong,especially in dry season. According toMr. Weerawut Pornrattanaphan, ahydrologist of Water ResourceDepartment of Thailand, the upperMekong dams have decreased theminimum discharge of the Mekong atChiang Saen station for 25 percent.He stated that during 1962-1992,before the Manwan dam construction,the mean of minimum discharge was752 CMS (Cubic Meter per Second).However, during 1993-2003, the meanof minimum discharge is only 569CMS2 . The information also showsthat the trend of the minimumdischarge is reduced in the long term.This means that the volum of themekong water is also reduced. (seetable 1)

Water Fluctuation

The Mekong rapids blasting which hasbeen implemented since the end of2001 has created the drastic waterfluctuation. In dry season of 2002-2003, the Chinese authorities announcedthe regulation of the river flow, allowingships to navigate for one day and thenpause for three days to allow for rapidsblasting. More recently in dry season2003-2004, it was announced that theriver was to be opened for traffic onlyfive hours in four days3 .

During January-April 2004, the mostunusual and rapid fluctuation in waterlevel was occurred when the Chineseteam constructed dyke at KhraiRapids on Lao-Burmese border, 68km downstream of Guan Lei port.(see table 2)

It is worried that the water fluctuationin the Mekong would be more fatal,due to three main factors. Firstly, thecompletion of Jinghong dam which isonly about 280 km upstream of ChiangSaen. Secondly, the Chineseauthorities’ plan to remove sand baralong the Mekong between Jinghongand Guan Lei to allow cargo ships ofup to 400 DWT to navigate year-round4 . Thirdly, the joint agreementamong four upper Mekong countriesto regulate the river water for dryseason navigation.

Table 1 Mekong River at Chiang Saen Minimum Discharge 1962-2003

Source: Department of Water Resources (2004).

2 Department of Water Resources, Report onWater Flow of the Mekong River, Bangkok,2004.

3 Xishuangbanna Maritime Authority,Instruction from the Navigation Improvement Timetable, 2003.

4 The Nation 13 August 2004

3

Social and EnvironmentalImpacts

The deterioration of the ecosystemmeans a decrease in food security forlocal people, as well as disrupted eco-nomic and social structures, which aretightly linked to a healthy ecosystem.According to in-dept research ofSoutheast Asia Rivers Network,fishers along the Mekong on Thai-Laoborder in Chiang Rai provincecomplained they could not fish inconditions where the river rose andthen lowered swiftly in a day or twoas in the past few dry seasons. Asmost of fish in the upper Mekong aremigratory species migrating upstreamfor reproduction, fish depend on theannual river flow. Thus, the waterfluctuation inevitably results in a great

decline of fish.

Thai Baan Research, a villagers’research on local knowledgeconducted by fishing communitiesalong the Mekong in Chiang Raiprovince, found that during the pastthree years, fish catch has beenreduced for 50 percent.

Far downstream in northeastern partof Thailand, fishers in NakornPhanom province on the Mekong riveralso insisted that the unusual waterfluctuation was witnessed. Thefluctuations harmed their fishingoccupation. They said fish did notmove out of its habitat when thewater level is rapidly altered.

Moreover, the water fluctuation alsoaffects the water level in the Mekong’s

Table 2 The Mekong River Level at Chiang Saen, Thailand 1991 and 2004

Source: Raw data from Department of Water Resources

tributaries and wetland areas in theNortheast Thailand. Mr.RattaphonPitaksombat of IUCN’s MekongWetlands Biodiversity Conservationand Sustainable Use Programmerevealed that the Songkarm River, theMekong’s tributary was also affected.According to Mr.Rattaphon, the waterfluctuation also occurred on theSongkarm River as far as more than 50kilometer from the mouth of the river.

Impacts on Lower MekongCountries

Downstream impacts of the UpperMekong development has also raisedconcern in the lower Mekong coun-tries. As the Prime Minister Hun Senwarned that Cambodia’s Tonle Saplake, a vital source of fish of the coun-

4

try, could dry up if developmentprojects are not handled carefully onthe Mekong River upstream from thelake5 .

For more information, please visitwww.searin.org ¡ÒâÖé¹-ŧ¢Í§¹éíÒ⢧·Õè¼Ô´¸ÃÃÁªÒµÔ Ê�§¼Å¡Ãзºµ�ÍÃкº¹ÔàÇȹ�áÁ�¹éíÒ

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5 AP/ENN, February 12, 2003

References

[1] Department of Water Resources,Report on Water Flow of the Mekong River,Bangkok,2004.[2] International Rivers Network, China’sUpper Mekong Dams Endanger MillionsDownstream, Briefing Paper 3, October:Berkley, 2002.[3] World Commission on Dams, Damsand Development: A New Framework forDecision-Making, London: Earth Scan,2002.[4] Xishuangbanna Maritime Authority,Instruction from the Navigation Improve-ment Timetable, 2003.[5] AP/ENN, February 12, 2003[6] The Nation, 13 August 2004

Recommendations

All riparian government shouldimmediately stop all works on thehydropower and river developmenton the Lancang-Mekong, andproperly conduct comprehensiveenvironmental and social impactassesments according to internationalstandards. These assesments shouldbe carried out in a transparent andparticipatory manner, with recogniz-ing the health and vitality of theMekong River and the lives of thosewho depend on it.

The World Commission on Dams’strategic priorities such as GainingPublic Acceptance, ComprehensiveOptions Assesment, SustainingRivers and Livelihoods, and SharingRivers for Peace, Development andSecurity, should be considered.

address: 78 Moo 10 Suthep Rd., TambolSuthep, Muang, Chiang Mai 50200

THAILANDTel.+66 53 278 334 fax.+66 53 283 609

Kai, Mekong seaweed, a source of income for women duringdry season, has decreased drastically due to the unususalwater fluctuation.