自由流动的河流生态系统对于保护生物多样性和提供生态系统商品和服务至关重要（1，2）。然而，在全球范围内，大多数大型河流的流量和连通性都因建造大坝而受到干扰，以满足日益增长的人口对水、能源和粮食生产的飙升需求（3，4）。因此，世界上大多数大型河流流域的淡水生物多样性现在都受到威胁，淡水渔业正在崩溃，河口三角洲由于上游的沉积物捕获而萎缩（2，5，6）。现在，许多注意力都集中在减轻严重改造的河流流域的巨大开发影响上，但保护仅存的几条自由流动的大型河流也同样重要，尤其是那些即将开发的河流（4，7），如东南亚的萨尔温河。
萨尔温江是东南亚最长的自由流动河流，也是该地区仅有的两条此类河流之一（与邻近的伊洛瓦底江一起）。萨尔温江支持着世界上一些生物多样性最强的地区，包括高水平的地方性，它为以前广泛分布的物种提供了一些仅存的自由流动的栖息地，如因水坝而从其他主要河流流域消失的安格利亚目（6，8）。
萨尔温江流域也是多种土著人民的家园，他们依靠河流谋生，并与河流系统保持着深厚的精神联系和相互依存关系。例如，泰国的克伦人建立了鱼类保护区，制定了正式的规则，并对违规行为进行处罚。该社区每年都会举行祈祷仪式，为当地的鱼类物种（如加拉属）祈福，并通过管理水位和抵御捕食者来积极保护它们的产卵栖息地（9）。
几十年来，萨尔温江流域的大坝建设一直遭到强烈而成功的反对。然而，后疫情时代对区域经济复苏的需求可能会重新激发人们对萨尔温江水电项目的热情。为了保护河流的自由流动状态，萨尔温江流域国家应建立一个有学术支持的强有力的证府间组织，以促进利益相关者之间的沟通与合作，并评估任何建造大坝的决定的成本和收益。这些努力必须纳入土著社区的利益、价值观和对这条河的长期了解，这些社区将受到萨尔温江自由流动地位的任何损失的最大影响。
保护河流还需要调整该地区的能源结构和经济发展模式。例如，证府应优先考虑使用较少能源的行业，如基于自然的旅游业，并推广其他可再生能源，如太阳能和风能。萨尔温江流经的国家应该抵制在仅存的几条自由流动的河流中修建大坝是不可避免的想法。相反，他们应该庆祝和保护只有这样的流域才能提供的独特的环境、社会、经济和精神价值观。
Free-flowing river ecosystems are essential to the protection of biodiversity and the provision of ecosystem goods and services (1, 2). Yet, at a global scale, the flow and connectivity of most large rivers have been disrupted by the construction of dams to meet the growing population’s soaring demands for water, energy, and food production (3, 4). Consequently, freshwater biodiversity is now imperiled in most large river basins around the world, freshwater fisheries are collapsing, and estuarine deltas are shrinking due to sediment capture upstream (2, 5, 6). Much attention is now focused on mitigating the impacts of immense development in heavily modified river basins, but protecting the few remaining large free-flowing rivers is equally important, especially those where development is imminent (4, 7), such as the Salween River in southeast Asia.The Salween River is the longest free-flowing river in southeast Asia and one of only two such rivers in the region (together with the neighboring Irrawaddy River). The Salween supports some of the most biodiverse areas in the world, including high levels of endemism, and it provides some of the only remaining free-flowing habitats for previously widespread species, such as anguillids, that have disappeared from other major river basins because of dams (6, 8).The Salween Basin is also home to diverse Indigenous peoples who depend on the river for their livelihoods and maintain deep spiritual connections and a reciprocal interdependency with the river system. For example, the Karen of Thailand establish fish sanctuaries with formalized rules and penalties for violations. The community conducts annual prayer ceremonies to bless endemic fish species (such as Garra spp.) and actively protects their spawning habitats by managing water levels and warding off predators (9).SIGN UP FOR THE SCIENCEADVISER NEWSLETTERThe latest news, commentary, and research, free to your inbox dailySIGN UPDam construction has been strongly and successfully opposed in the Salween Basin for many decades. However, the demand for regional economic recovery in the post-pandemic era could renew enthusiasm for Salween hydropower projects. To protect the river’s free-flowing status, the Salween Basin nations should establish a robust intergovernmental organization with academic backing to facilitate communication and cooperation among stakeholders and to assess the costs and benefits of any decisions to construct dams. Such efforts must incorporate the interests, values, and long-held knowledge of the river held by Indigenous communities, which stand to be most affected by any loss to the Salween’s free-flowing status.Safeguarding the river will also require adjustments to the energy structure and economic development model in the region. For example, governments should prioritize industries that use less energy, such as nature-based tourism, and promote other renewable energy sources, such as solar and wind power. Countries through which the Salween flows should resist the idea that building dams in the few remaining free-flowing rivers is inevitable. Instead, they should celebrate and protect the unique environmental, social, economic, and spiritual values that only such river basins can provide.
JUAN TAO, NICK BOND, NYO NYO TUN, AND CHENGZHI DING Authors Info & Affiliations
SCIENCE27 Jul 2023Vol 381, Issue 6656pp. 383-384DOI: 10.1126/science.adi9117