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1 The Mekong under threat Milton Osborne Chinadialogue 15 January 2010 Until the 1980s the Mekong River flowed freely for 4,900 kilometres from its 5,100 metre high source in Tibet to the coast of Vietnam, where it finally poured into the South China Sea. The Mekong is the world s twelfth longest river, and the eighth or tenth largest, in terms of the 475 billion cubic metres of water it discharges annually. Then and now it passes through or by China, Burma (Myanmar), Laos, Thailand, Cambodia and Vietnam. It is south east Asia s longest river, but 44% of its course is in China, a fact of capital importance for its ecology and the problems associated with its governance. In 1980 not only were there no dams on its course, but much of the river could not be used for sizeable, long distance navigation because of the great barrier of the Khone Falls, located just above the border between Cambodia and Laos, and the repeated rapids and obstacles that marked its course in Laos and China. Indeed, no exaggeration is involved in noting that the Mekong s overall physical configuration in 1980 was remarkably little changed from that existing when it was explored by the French Mekong Expedition that travelled painfully up the river from Vietnam s Mekong Delta to Jinghong in southern Yunnan in 1866 and This was the first European expedition to explore the Mekong from southern Vietnam into China and to produce an accurate map of its course to that point. Since 2003, the most substantial changes to the Mekong s character below China have related to navigation. Following a major program to clear obstacles from the Mekong begun early in the present decade, a regular navigation service now exists between southern Yunnan and the northern Thai river port of Chiang Saen. It is not clear whether the Chinese, who promoted the concept of these clearances and carried out the work involved, still wish to develop navigation further down the river, as was previously their plan. To date, the environmental effects of the navigation clearances have been of a limited character. The Mekong plays a vital role in the countries of the Lower Mekong Basin (LMB): Laos, Thailand, Cambodia and Vietnam. (Burma is not within the basin). In all four LMB countries the Mekong is a source of irrigation. In Vietnam s Mekong Delta the annual pattern of flood and retreat insure that this region contributes over 50% of agriculture s contribution to the country s GDP. For all four LMB countries the Mekong and its associated systems, particularly Cambodia s Great Lake (Tonle Sap), are a bountiful source of fish, with the annual value of the catch conservatively valued at US$2 billion. More than 70% of the Cambodian population s annual animal protein consumption comes from the river s fish. Eighty per cent of the Mekong s fish species are migratory, some travelling many hundreds of kilometres between spawning and reaching adulthood. Overall, eight out of 10 persons living in the LMB depend on the river for sustenance, either in terms of wild fish captured in the river or through both large and small scale agriculture and horticulture. Since the 1980s, the character of the river has been steadily transformed by China s dambuilding program in Yunnan province. The important changes that had taken place on the course of the river since 1980 and up to 2004 were outlined in the Lowy Institute Paper, River at Risk: The Mekong and the Water Politics of Southeast Asia. In 2010 three hydroelectric dams are already in operation and two more very large dams are under construction and due for completion in 2012 and Plans exist for at least two further dams, and by 2030 there could be a cascade of seven dams in Yunnan. Even before that date and with five dams commissioned, China will be able to regulate the flow of the river, reducing the floods of the wet season and raising the level of the river during the dry. In building its dams, China has acted without consulting its downstream neighbours. Although until now the effects of the dams so far built have been limited, this is set to change within a decade, as discussed below. For despite the limited environmental costs of the dams China has so far completed, and of the river clearances to aid navigation, this state of affairs will change once China has five

2 dams in operation. And the costs exacted by the Chinese dams will be magnified if the proposed mainstream dams below China are built. Even if no dams are built on the mainstream below China, the cascade to which it is committed will ultimately have serious effects on the functioning of the Mekong once the dams are used to control the river s flow. This will be the case because the cascade will: * Alter the hydrology of the river and so the current flood pulse, the regular rise and fall of the river on an annual basis which plays an essential part in the timing of spawning and the migration pattern. This will be particularly important in relation to the Tonle Sap in Cambodia, but will have an effect throughout the river s course; * Block the flow of sediment down the river which plays a vital part both in depositing nutrients on the agricultural regions flooded by the river and also as a trigger for fish migration at present well over 50% of the river s sediment comes from China; * At least initially cause problems by restricting the amount of flooding that takes place most importantly in Cambodia and Vietnam; and * Lead to the erosion of river banks. Proposed dams below China So China s dam building plans are worrying enough, but the proposed new mainstream dams would pose even more serious concerns. In contrast to what has occurred in China, and until very recently, there have been no firm plans for the construction of dams on the mainstream of the Mekong below China. This situation has changed over the past three years. Memoranda of Understanding have been signed for 11 proposed dams: seven in Laos; two between Laos and Thailand; and two in Cambodia. The proposed dams are being backed by foreign private capital or Chinese state backed firms. Government secrecy in both Cambodia and Laos means that it is difficult to judge which, if any, of these proposed dams will actually come into being. Attention and concern have focused on two sites: Don Sahong at the Khone Falls in southern Laos and Sambor in north eastern Cambodia. The reason for this attention is that if built these dams would block the fish migrations that are essential to insure the food supplies of Laos and Cambodia. Those built at sites higher upstream would cause the least damage to fish stocks, but if, as currently seems possible, the most likely dams to be built would be at Don Sahong and Sambor, the costs to fish stocks could be very serious. This is because unanimous expert opinion judges that there are no ways to mitigate the blocking of fish migration that would occur if these dams are constructed. None of the suggested possible forms of mitigation fish ladders, fish lifts, and alternative fish passages are feasible for the species of fish in the Mekong and the very large biomass that is involved in their migratory pattern. Fish ladders were tried and failed at the Pak Mun dam on one of the Mekong s tributaries in Thailand in the 1990s. Why are the governments of Laos and Cambodia contemplating the construction of dams that seem certain to have a devastating effect on their populations food security? The answers are complex and include some of the following: * A lack of knowledge at some levels of government; * A readiness to disregard available information on the basis that it may be inaccurate; and * A belief or conviction that fishing is old fashioned, whereas the production of hydroelectricity is modern.

3 In Cambodia s case, and in particular in relation to the proposed dam at Sambor, the fact that a Chinese firm is seeking to construct the dam raises the possibility that prime minister Hun Sen is unready to offend the country that has become Cambodia s largest aid donor and Cambodia s most trusted friend. In Laos, the proposal for a dam at Don Sahong is very much linked to the interests of the Siphandone family for whom southern Laos is a virtual fief. Of all the proposed dam sites, Don Sahong is the most studied in terms of knowledge of fisheries so that it can be safely said that the planned dam would wreak havoc on a migratory system that involves fish moving through the Hou Sahong channel throughout the year, movement that takes place in both directions, upstream and downstream. In the face of the threats posed by both the Chinese dams and those proposed for the downstream stretches of the river, there is no existing body able to mandate or control what individual countries choose to do on their sections of the Mekong. The agreement establishing the Mekong River Commission (MRC) in 1995 does not include China or Burma, and though the latter s absence is not important, the fact that China is not an MRC member underlines the body s weakness. In any event, the MRC members commitment to maintaining the Mekong s sustainability has not overcome their basic commitment to national self interest. A prime example of this is the manner in which the Lao government has proceeded in relation to the proposed Don Sahong dam. For at least two years while the dam was under consideration there was no consultation with Cambodia. Similarly, so far as can be judged, Cambodia s consideration of a possible dam at Sambor has taken place without consultation with the governments of either Laos or Vietnam. At the moment the best hope is that both the Cambodian and Lao governments will abandon their plans for Sambor and Don Sahong. If they do not, the future of the Mekong as a great source of food, both through fish and agriculture, is in serious jeopardy. At the time of writing the intentions of the Lao and Cambodian governments remain uncertain. Concern about dams in China and the LMB is given added importance in the light of worries associated with the likely effects of climate change in the region through which the river flows. Research suggests there will be a series of challenges to the Mekong s future ecological health. Until recently concerns about the likely impact of climate change tended to focus on the ongoing reduction in the size of the glaciers from which its springs in the Himalayas and which feed it as the result of snow melt. But while there is no doubt that a diminishment in size of the glaciers feeding the Mekong is taking place, recent research has suggested that a more immediate serious threat to the river s health will come from sea level changes, particularly as rising levels could begin to inundate large sections of Vietnam s Mekong Delta. To what extent the threat posed by rising sea levels will be affected by another predicted development linked to climate change greatly increased precipitation leading to more flooding during the wet season is not yet clearly established. But research is pointing to a greatly increased precipitation that is likely to cause major increases in flooding in the future, possibly as early as Against the pessimistic views outlined in this article perhaps the best that can be hoped for is that once serious consequences begin to become apparent advice can be offered to mitigate the worst effects of the developments taking place. Where once it was appropriate to write of risks, when assessing the Mekong s future it is now time to write of fundamental threats to the river s current and vital role in all of the countries of the Lower Mekong Basin. Milton Osborne is visiting fellow at the Lowy Institute. He has been associated with the southeast Asian region since being posted to the Australian embassy in Phnom Penh in Osborne is the author of 10 books on the history and politics of south east Asia, including The Mekong: turbulent past, uncertain future (2006) and Southeast Asia: an introductory history. This is an edited version of an earlier article, The Mekong River Under Threat," published in The Asia Pacific Journal, , January 11, It is used here with permission.

4 面米威的湄公河奥斯本 2010 年 1 月 15 日在去的三十年里, 南最的河流已生了很大的化目前, 湄公河下游流域的食安全而未米奥斯本撰文道 20 世 80 年代之前, 湄公河从西藏 5100 米高的源奔涌而下, 自由奔 4900 公里, 抵达越南海岸, 并最流入中南海湄公河是世界第十二的河流, 其水量每年 475 立方千米, 居世界第八或第十位古往今来, 湄公河流的家有中甸老泰柬埔寨和越南, 是南最的河流然而, 由于其的 44% 在中国境内, 因此, 湄公河的生和治理有足重的影 1980 年, 湄公河上不有水, 而且由于位于柬埔寨和老之界上的孔恩瀑布的阻, 以及在老和中河段上不出的湍流和障, 在其大部分的河道上无法行大模距离的航行毫不夸地,1980 年的湄公河整体流域形与 1866~1867 年法国湄公河探河流行考察相比, 化并不大年, 支法探千辛万苦越南湄公河三角洲出, 逆流而上到云南南部的景洪市是洲探首次越南南部至中一段的湄公河流域行勘察, 并制了一份段流域的地 2003 年, 中国下游湄公河流域最著的化就是通航有了大改始于十年初期的湄公河河道大型清障目的展, 云南南部到泰北部清盛港之的河段目前已正式通航清障工程最先由中提出并施但是中方是否仍然愿意按照之前的划航一步向下游延伸, 目前不得而知至今日, 航清障目的境影很有限

5 老泰柬埔寨及越南等湄公河下游流域(LMB) 国家而言, 湄公河的作用足重 ( 甸不在流域范内 ) 所有四流域家, 湄公河灌溉了他的土地越南湄公河三角洲洪水每年有律的退确保了地的品值占 GDP 的 50% 些家, 湄公河及相水系, 特是柬埔寨的大湖洞里湖的水源丰富据保守估, 其年值高 20 美元柬埔寨人民的年物蛋白入量中有 70% 来自于淡水湄公河中 80% 的洄游物种其中一些卵到育成成要跋涉百公里而言之, 下游湄公河流域的人口中, 每十人中就有八人以河生有的人打, 有的人事模各异的和花卉从 20 世 80 年代始, 受中云南省境大修建目的影, 湄公河流域的特征已不地生了很大的化伊研究所的文, 危河流 : 湄公河及南的水政治 1980 年到 2004 年止湄公河所生的重大化行了概述 2010 年, 已有三座水大投入使用此外, 有座模更大的大正在建中, 分于 2012 年和 2017 年竣工根据有的划, 修建至少座水到年, 云南省将建成七座梯大在那之前, 即便是在只有五座大的情下, 中也能河流的流量行控制, 降低雨季的水位, 提高旱季的水位中在有征其下游邦的意的情下便始了大的修建管到目前止, 大所的影很有限然而, 一情在十年生改此, 我在下文中加以尽管到目前止, 中建成的大以及了通航所行的河道清障工作所生的境成本有限但是, 一旦五座大始用, 事生改同, 如果中下游建的干流水一旦建成, 中大所生的成本也被放大即便是中国下游不再修建干流水, 但是, 一旦梯大始控制河流的水量, 已建成的梯大最湄公河的功能生重的影之所以出种情是因大生以下的一些影 : * 河流的水文及有的洪水脉冲都将生改洪水是指河水每年有律的跌洪水的卵以及洄游方式有很大的影它影整湄公河流域, 特是柬埔寨的洞里湖 * 阻碍了河流沉物向下游的泛洪地分的累以及的洄游是至重要的因素目前,50% 以上的河流沉物自中 * 通主要限制柬埔寨和越南洪水量的方法至少一始就引一些 * 同, 致河堤受到侵

6 中国下游建的大中国的大修建划已足以令人不已但是, 建中的新的干流大造成更加重的与中已付施相比, 直到近期, 中下游的湄公河有确切的干流大修建划而一在去的三年生了化有十一座建大的解忘已署十一座大中有七座位于老, 座位于老和泰之, 有座在柬埔寨些建中的大得到了外私有本及具有有背景的中企的大力支持柬埔寨和老的政府此事秘而不宣的度人很判定些大中究竟哪几真正工修建目前引起人重和注的座大是 : 位于老南部孔恩瀑布的沙宏大, 以及位于柬埔寨北部的松博大人之所以注它是因些大一旦建成, 妨的洄游而洄游是保障老和柬埔寨食物供的重要因素在靠近上游位置建造的大源的影小但是, 照目前的情看, 大最有可能修建的位置在沙宏和松博一旦座大建成, 源生非常重的影家一致, 如果座大建成, 其洄游造成的阻是任何手段也法的梯升降式道以及替代性道等可能的解决方式都无法有效解湄公河的种群以及与洄游模式相的大量生物所面的 20 世 90 年代, 泰国就曾在位于湄公河一支流上的帕穆水采用梯的方式解些, 但是最是以失而告既然几乎可以肯定大食品安全造成性的影, 那么, 什么老和柬埔寨政府要意考修建大呢? 的答案非常复, 其中包括以下几个方面 : * 政府内部一些相知缺乏了解 ; * 在有可能并不正确的基上, 忽了一些有用的信息 ; * 抱有落后, 而水力先的或想法就柬埔寨而言, 特是于划在松博修建大的上, 一家中企正成大的承建方, 人不禁怀疑, 洪森理有可能做好充分的准拒柬埔寨最大的援助国和最值得信的朋友而在老, 修建沙宏大的提在很大程度上是与西潘敦家族的利益有因老南部正是家族的地在所有的址中, 于沙宏的研究最透因此, 可以肯定地, 建中的大全年上游和下游向游洪沙宏河道的洄游系生重的影面中大以及下游那些建中的大所的威, 目前有一能

7 有能力命令或者遏制各家在其境湄公河段上的所作所湄公河委 (MRC)1995 年的中未能包括中和甸管后者的包括与否足重, 然而, 中的缺席志的弱力在任何情况下, 湄公河委成所做出的保湄公河可持性的承都不凌于各自家自身的基本利益之上在与建的沙宏大有的上, 老政府所采取的度就是一很好的例子考修建大至少花了年的而在年中, 未就此事征求柬埔寨方面的任何意有偶, 就目前的情判, 柬埔寨在考修建松博大也未曾征求老或越南政府的意目前, 我唯一的希望就是柬埔寨和老的政府能放他在松博和沙宏修建大的划如果他持己, 那么, 作及品等食物的主要源, 湄公河未来的命运将岌岌可危截至撰写本文, 老和柬埔寨政府的意仍不明朗于人气候化有可能湄公河流地造成的影的, 中及湄公河下游流域家修建大的注就得更加重要研究示, 湄公河未的生健康面一系列的挑到目前止, 人气候化有可能造成的影的注主要集中在冰川体的不小上而些喜拉雅冰川正是湄公河的源地冰川的融水源源不地滋湄公河管冰川的消融毋庸置疑, 然而近期的研究却示, 河流健康所面的一更加迫切更加峻的威是海平面的化特是海平面的上升, 越南湄公河三角洲的大部分被海水所淹海平面上升所的威究竟在多大程度上受到另一与气候化相的因素致雨季洪水增多的降雨量大幅度增加的影响, 目前法确定然而, 研究指出, 最早有可能到 2030 年, 降雨量的大幅度增加将有可能会致未洪水的大大增加基于本文中所述的悲, 也我最后的希望就是, 一旦重的后果始, 人能拿出有效的建解事展程中所造成的最劣影我在湄公河的未行估, 曾各种入手而在我一下前湄公河在其下游家中足重的地位所面的主要威米奥斯本 : 伊研究所者自 1959 年他被派到澳大利金使起, 他就与南地有密不可分的系斯本著十部, 其容涉及南地的史和政治, 其中包括湄公河 : 的去, 未卜的未 (2006) 及南史等本文早些候曾以面威的湄公河表于 The Asia Pacific Journal(2010 年 1 月 11 日,2 2 10) 作者授在此表

8 作者在其伊研究所文 (2009,27) 的基上撰成此文原文此全文, 需要在入网址后入前年份首片柬埔寨桔井省松博大的建地由卡米德, 自国河流

has become a rarity. In other words, the water resources that supply the needs in Taiwan depend crucially on the reservoirs built at least more than t

has become a rarity. In other words, the water resources that supply the needs in Taiwan depend crucially on the reservoirs built at least more than t 臺灣水利第 64 卷第 1 期民國 105 年 3 月出版 Taiwan Water Conservancy Vol. 64, No. 1, March 2016 論台灣水資源開發的必要性 The Essentiality of Water Resource Development in Taiwan * 虞國興 GWO-HSING YU 淡江大學