Environmental and Human Impacts of Lancang-Mekong Mainstem and Tributary Dams on China, Laos, Thailand, Myanmar, Cambodia, and Vietnam

The Lancang-Mekong River in China, Laos, Thailand, Myanmar, Cambodia, and Vietnam is the soul and heart of mainland Southeast Asia. Over 60 million people depend on the river and its tributaries for food, transportation, water, and other necessities of life. The river supports one of the world’s most diverse fisheries, second only to Brazil’s Amazon River. Lancang-Mekong and tributaries are already heavily dammed primarily in China, Laos, Thailand, and Cambodia, with many more dams planned or under construction. Dams can worsen the impact of periodic droughts in the Lancang-Mekong basin and block the river’s “pulse effect” that spreads water and nutrients needed for fishing and farming onto the floodplains and delta. The headwaters of the Lancang are in China and its waters are considered a national resource. China regards the Lancang, Yangtze and Yellow rivers as a free resource rather than a shared resource. The primary difference between these rivers is the Lancang flows from China into and through other countries and not directly into a sea or ocean. China and Myanmar have not joined the Mekong River Commission (MRC) as full members but have been Dialogue Partners since 1996. Over the past thirty years, China’s Lancang policies and actions have reflected its national resource interests. China has actively engaged with individual transboundary countries at various levels including environmental, conservation, and economic agreements. The primary objective of this study is to assess the environmental and human impacts of all Lancang-Mekong mainstem and tributary dams and the plans by many countries for more hydropower utilizing the potential of the river as the continent’s energy lifeline. Future dams need to include fish ladders and navigation locks to reduce the environmental impacts on fish populations, natural resources, navigation, and livelihoods. Strengthening of international collaboration via the MRC or by individual or multiple country agreements to address Lancang-Mekong’s sustainable transboundary development goals is recommended. When new Lancang-Mekong and tributary dams are built within any of the transboundary watershed countries, additional communities will need to be resettled. Significant environmental and human impacts are observed. Steps will have to be taken by all the concerned countries to prevent these problems and to ensure that people’s livelihoods are restored after resettlement.

Water Cooperation Priorities in the Lancang-Mekong River Basin Based on Cooperative Events Since the Mekong River Commission Establishment

The Lancang-Mekong River has attracted much attention from researchers, but the cooperation on water issues in this river basin has been limited, even after the establishment of the Mekong River Commission(MRC). Cooperation on water resources has been determined as one of the key priority areas in the Lancang-Mekong Cooperation Mechanism, but there are no details of targets. In order to establish the priorities of water cooperation under the mechanism, we adopted nine categories to classify the objectives of 87 water cooperation events based on the ‘Lancang-Mekong Water Cooperative Events Database' from 1995 to 2015. Based on the occurrence of cooperative events, cooperative objectives, cooperative scales, and approaches to cooperation, we conducted statistical, correlation, and text analyses. Our analyses indicated the following results: under the impact of economic conditions inside and outside the river basin, full cooperation appeared more difficult than bilateral and multilateral cooperation. Each of the partners adopted different preferences for cooperation targets. Cooperation with more definite objectives was easier to establish than cooperation with broader and more complex objectives. The potential objectives for water cooperation were navigation, hydropower, joint management, data sharing, flood control and water use. Because hydropower development is controversial, and because water cooperation is avoided by most existing regional cooperation mechanisms due to its complexity, we suggest the following priority areas for water cooperation in the Lancang-Mekong River Basin. 1) Navigation and flood control/drought relief are attractive objectives for all the riparian countries across the whole watershed. 2) Data sharing should be a priority for cooperation in the watershed due to its laying the foundation for the equitable and reasonable utilization of transboundary waters. 3) Hydropower is an objective best implemented mainly through bilateral cooperation, and on tributaries.

Hydrological Simulation Using TRMM and CHIRPS Precipitation Estimates in the Lower Lancang-Mekong River Basin

Satellite-based products with high spatial and temporal resolution provide useful precipitation information for data-sparse or ungauged large-scale watersheds. In the Lower Lancang-Mekong River Basin, rainfall stations are sparse and unevenly distributed, and the transboundary characteristic makes the collection of precipitation data more difficult, which has restricted hydrological processes simulation. In this study, daily precipitation data from four datasets(gauge observations, inverse distance weighted(IDW) data, Tropical Rainfall Measuring Mission(TRMM) estimates, and Climate Hazards Group InfraRed Precipitation with Stations(CHIRPS) estimates), were applied to drive the Soil and Water Assessment Tool(SWAT) model, and then their capability for hydrological simulation in the Lower Lancang-Mekong River Basin were examined. TRMM and CHIRPS data showed good performances on precipitation estimation in the Lower Lancang-Mekong River Basin, with the better performance for TRMM product. The Nash-Sutcliffe efficiency(NSE) values of gauge, IDW, TRMM, and CHIRPS simulations during the calibration period were 0.87, 0.86, 0.95, and 0.93 for monthly flow, respectively, and those for daily flow were 0.75, 0.77, 0.86, and 0.84, respectively. TRMM and CHIRPS data were superior to rain gauge and IDW data for driving the hydrological model, and TRMM data produced the best simulation performance. Satellite-based precipitation estimates could be suitable data sources when simulating hydrological processes for large data-poor or ungauged watersheds, especially in international river basins for which precipitation observations are difficult to collect. CHIRPS data provide long precipitation time series from 1981 to near present and thus could be used as an alternative precipitation input for hydrological simulation, especially for the period without TRMM data. For satellite-based precipitation products, the differences in the occurrence frequencies and amounts of precipitation with different intensities would affect simulation results of water balance components, which should be comprehensively considered in water resources estimation and planning.

FACILITATING REGIONAL SUSTAINABLE DEVELOPMENT THROUGH INTEGRATED MULTI-OBJECTIVE UTILIZATION, MANAGEMENT OF WATER RESOURCES IN THE LANCANG-MEKONG RIVER BASIN

The Lancnag Mekong River is the most important international river across China and Southeast Asia, If it is developed according to 'Great Mekong Subregional Cooperation Plan' [9] prepared by ADB, the area directly affected will be up to over 2.32 million km 2, the population over 220 million, and the natural environment, and socio-economic conditions within a large area will be greatly changed. 'Agreement on Cooperation for Sustainable Development of Mekong Basin' signed by the four riparian countries along the lower Mekong River on April 5, 1995 provides a new opportunity for sustainable development of the Basin. According to preliminary analysis, if the multipurpose utilization of the water resources is the target for carrying out integrated planning and management, and the efforts are made 1) to focus on energy exploitation on the Lancang River Mainstream and the tributaries of the lower Mekong River; 2) to build gated weirs at Tonle Sam; 3) to construct spillways at the Mekong Delta; 4) to facilitate flood dykes in big cities and on both banks of the mainstream which are concentrated with population and farmland and liable to be flooded, and 5) to strengthen networks for forecasting hydrological and meteorological conditions, then all problems such as power demand, irrigation, flood, salt water intrusion as well as acid water erosion to soil could be solved without constructing large cascaded stations and dams on the lower Mekong Mainstream. This will not only avoid input of great number of fund, large scale resettlement and land inundation, but also prevent aquatic organisms living in Mekong River from being injured due to dam construction, and promote the sustainable development of the Basin.

Projection of temperature change and extreme temperature events in the Lancang–Mekong River basin

The Lancang–Mekong River basin(LMRB) is under increasing threat from global warming. In this paper, the projection of future climate in the LMRB is explored by focusing on the temperature change and extreme temperature events. First, the authors evaluate the bias of temperature simulated by the Weather Research and Forecasting model. Then, correction is made for the simulation by comparing with observation based on the non-parametric quantile mapping using robust empirical quantiles(RQUANT) method. Furthermore, using the corrected model results, the future climate projections of temperature and extreme temperature events in this basin during 2016–35, 2046–65, and 2080–99 are analyzed. The study shows that RQUANT can effectively reduce the bias of simulation results. After correction, the simulation can capture the spatial features and trends of mean temperature over the LMRB, as well as the extreme temperature events. Besides, it can reproduce the spatial and temporal distributions of the major modes. In the future, the temperature will keep increasing, and the warming in the southern basin will be more intense in the wet season than the dry season. The number of extreme high-temperature days exhibits an increasing trend, while the number of extreme low-temperature days shows a decreasing trend. Based on empirical orthogonal function analysis, the dominant feature of temperature over this basin shows a consistent change. The second mode shows a seesaw pattern.

Soil and water loss in the Lancang River-Mekong River watershed (in Yunnan section, China) and its control measures

According to a lot of hydrological and environmental monitoring data, the condition of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is described. The occurrence and development of soil and water loss is analyzed. The conclusion is that: (1) generally, the situation of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is light, however, soil and water loss in some regions is serious, especially in the middle reach area of the river; (2) soil and water loss in the Lancang River Mekong River (in Yunnan section, China) watershed presents developing tendency and it is mainly caused by human beings. In accordance with these results, the control measures for soil and water loss are discussed.

Groundwater status and associated issues in the Mekong-Lancang River Basin： International collaborations to achieve sustainable groundwater resources

Groundwater is an important and readily available source of fresh water in the Mekong-Lancang River Basin. With a rapid population growth and increasing human activities, an increasing number of countries in the Mekong-Lancang River Basin are experiencing depleted and degraded groundwater supplies. In transboundary river basins, such as the Mekong-Lancang River, prioritizing the use of the shared aquifer by one riparian government may affect the opportunities of other riparian governments and lead to potential water conflicts between neighboring countries. To promote the sharing of strategies and information for the sustainable and equitable use of water resources of the shared basin, international collaborative workshops on groundwater resources have been organized for all Mekong-Lancang River countries. These workshops provide an opportunity to communicate and discuss nationally sensitive issues on groundwater by the associated countries, with topics covering multiple aspects of groundwater, such as the groundwater status in the basin, quality issues, water use conflicts, hydrological information gaps, management policies and capacity building for successful water resource management. Consensus has been reached by all countries on the importance of catchment-based groundwater management and the need for close communication among the countries. Strategies for managing transboundary aquifer issues must foster international collaboration based on the regional network, influence national networks and enhance the capacity to building maps and monitoring systems based on associated databases. The sustainability of water resources cannot be achieved without the integrated involvement and contributions by multiple countries and various stakeholders. Therefore, collaborative workshops provide a great opportunity to further our understanding of the hydrologic processes of the Mekong River Basin, share the benefits of the aquifer and provide a strategy and vision for sustainable water resource management in the Mekong-Lancang River countries.

基于多维Copula函数的澜沧江-湄公河流域气象干旱特征分析

为全面揭示变化环境下澜湄流域多维气象干旱特征,采用标准化降水蒸散指数SPEI表征流域气象干旱,基于游程理论分别提取澜沧江段和湄公河段上、中、下游流域1901—1960年和1961—2021年两个时段的干旱事件,利用Copula函数分别构建两个时段不同子流域二维和三维干旱特征变量联合分布,计算不同干旱特征变量组合条件下的干旱联合发生概率,对比分析不同子流域多维气象干旱特征的时空变化。结果表明:时间上,1961—2021年各子流域平均干旱程度均较1901—1960年更严峻,尤其是极端干旱事件(单变量累积频率为25%、50%)的多维干旱联合发生概率增幅最大;空间上,1961—2021年,随着干旱历时、烈度和烈度峰值的增加,“或”情况下多维干旱联合发生概率最高值区自北向南转移,“且”情况下多维干旱联合发生概率最高值区自南向北转移。

澜沧江下游补远江大型底栖动物群落结构的时空分布及其影响因素

自然流淌的支流在维持建坝河流水生生物多样性中起着重要作用。补远江是澜沧江下游的重要一级支流,保持了较为天然的河流状态,人类活动干扰相对较少,是流域土著鱼类保护区和水生生物重要栖息地。在澜沧江流域水电开发的背景下,掌握补远江大型底栖动物群落结构的时空分布及其影响因素,对澜沧江乃至西南河流的水生生物多样性保护和恢复具有重要参考意义。于2019年4月(旱季)和2019年10月(雨季)对补远江的大型底栖动物进行了详细调查,共检出大型底栖动物150个分类单元,隶属于5门7纲68科,其中水生昆虫121种,软体动物20种,蛭类3种,寡毛类2种,甲壳类2种,涡虫、线虫各1种。毛翅目和蜉蝣目为全流域优势类群。补远江底栖动物密度和生物量在旱季和雨季均表现为上游大于中下游,物种丰富度和Shannon-Wiener多样性指数在雨季显著高于旱季。功能摄食类群中,滤食者(41.09%)和收集者(31.81%)占绝对优势,其次为刮食者(11.00%)、捕食者(11.21%),撕食者(4.89%)较少。Mantel检验分析表明,河宽(RW)、硝态氮(NO_(3)^(-)-N)、化学需氧量(COD Mn)是影响补远江大型底栖动物群落结构的主要环境因子;不同功能摄食类群所受到的环境影响因素不同。生物指数(BI)和生物监测工作组记分(BMWP)系统评价显示,补远江大部分样点处于良好及以上水平,少数样点处于中等及以下水平,总体水生态状况良好。

澜沧江—湄公河跨境流域土地利用变化及生态环境质量演变

【目的】研究澜沧江—湄公河跨境流域土地利用变化及生态环境质量地域分异。【方法】运用动态度模型和地学信息图谱理论,基于Global Land 30、全球30 m精细地表覆盖数据集等,分析澜沧江—湄公河跨境流域在2000—2010年和2010—2020年2个时序单元的土地利用变化;构建生态环境质量评价体系,采用探索性空间数据分析方法探究其分异。【结果】澜沧江—湄公河跨境流域土地利用类型变动速率差异明显;在图谱空间中,长期稳定型的分布最广,图谱变化类型呈片状零散分布;2000—2020年,研究区土地利用类型转移呈多样性和不均衡性,林地为主要转出类型,贡献了总转出面积的46%以上。2000—2010年,研究区不同土地利用类型空间呈南北弱、中间强的散点分散格局;2010—2020年,则呈南北强、中间弱的片状集中格局,且不同类型的涨落势具有显著的相似性。生态环境质量空间格局总体呈南高北低的片状分布,具有较弱的空间正相关性,生态环境发展水平的空间俱乐部收敛特征显著性较低。【结论】澜沧江—湄公河跨境流域土地利用具有图谱变化稳定性、地域分异国别性和生态质量差异性,耕地和草地转变为林地有助于改善生态环境,但林地转为耕地以及城镇化导致了生态环境恶化。

气候变化影响下澜湄流域下游水稻生产用水量模拟与分析

农业用水是社会经济用水的主要行业,气候变化对农业用水的影响可能改变区域的水资源供需情势。以澜沧江-湄公河流域下游为研究区,基于ERA5-Land数据集和最新的CMIP6气候预测数据,选用SSP1-2.6、SSP2-4.5、SSP5-8.5三种排放情景,AquaCrop模型将非生产性土壤蒸发和生产性作物蒸腾分离,将水稻生长期内蒸腾总量作为水稻生产用水量,模拟了澜沧江-湄公河流域下游历史和未来时期水稻生产用水量,分析了水稻生产用水量的变化情况及其与温度、降水和CO_(2)浓度之间的相关关系。结果表明:澜沧江-湄公河流域下游水稻生产用水量在空间上表现为北多南少,总体呈现逐年减少趋势,且在SSP5-8.5情景下趋势更加明显。SSP5-8.5情景下的未来远期,澜沧江-湄公河流域下游水稻生产用水量将减少29.7%。与温度和降水相比,水稻生产用水量和CO_(2)浓度之间的相关性最强。SSP5-8.5情景下的未来远期,在泰国的相关系数为-0.875,其余国家各季度下的相关系数均小于-0.9。

周边外交方针指引下澜沧江-湄公河综合执法安全合作中心的建设与展望

周边外交是习近平新时代外交思想的重要组成部分,做好周边外交工作是维护国家主权、安全、发展利益的需要。澜沧江-湄公河综合执法安全合作中心是由流域六国共同创建的新型次区域执法安全合作机制,是澜湄流域的首个综合性的执法安全合作类政府间国际组织。倡导和参与澜湄合作是中国打造周边命运共同体的生动实践,也是对亲诚惠容周边外交理念的具体落实,对于维护我国周边大环境稳定具有示范意义。为适应周边安全环境的迫切需要,配合我国国家角色转变,澜湄执法中心应秉持安全促发展理念,综合运用政治、经济、安全等多种手段,不断探索更高层次的湄公河流域执法安全合作关系,成为我国弘扬共享安全理念、增进与周边国家政治互信的平台,以配合我国周边安全战略。

人类命运共同体视域下跨境水资源的研究进展与展望

基于CiteSpace可视化分析软件,对2013—2022年CNKI中跨境水资源相关文献进行了梳理,从整体跨境水资源与典型国际河流这两个层面分析了跨境水资源的研究进展和前沿动态。结果显示:人类命运共同体倡议提出后,跨境水资源研究经历了相对平稳和快速增长两个阶段;跨境水资源研究的核心作者主要是徐宗学、陈晓宏、何大明、周海炜等,这些学者之间已经形成了部分团队合作;河海大学商学院、中国科学院大学、武汉大学水资源与水电工程科学国家重点实验室等是跨境水资源的主要研究机构,各研究机构间合作较少;跨境水资源研究视角多元化,其中国际水法、水外交、水安全、水利益等是研究热点,国际河流中澜沧江和珠江流域是研究热点;跨境水资源研究最新进展主要体现在流域共同体建设上,并已提出构建澜湄流域水安全共同体;未来跨境水资源研究热点可能是利益共同体与生态共同体的构建、跨境水冲突的应对机制与补偿机制、结合地缘经济政治与粮食安全等领域的研究。

Southwest China and Southeast Asia: towards sustainability through cooperative development and management of international rivers

The western part of China borders on South and Southeast Asia. Of the numerous well known international rivers sharing with the two regions, the Lancang Mekong River has been most extensively studied in the world for its important strategic position, rich resources, prosperous potential market as well as considerable opportunities for investment and development. The sustainable multipurpose development in this area has increasingly become the focus of international regional cooperation, and great attention has been paid to this area by the international society. Up to now, at least 10 major actions in the international regional cooperation are expected in this area. This paper intends, at the angle of geography and with the overall target of promoting the sustainable development in the basin through international cooperations, to study the international position, the potential and the prospects for development of the Lancang Mekong River, to analyze the main problems in this international cooperation, to propose targets and prospects for such cooperation, and to indicate the way for geographers to participate in such research.

“澜湄合作”构筑次区域粮食安全共同体

粮食问题关系发展与安全,既是经济命题更是政治命题,是国家安全的重要组成部分。在澜沧江-湄公河次区域内,各国自然资源禀赋高度互补,农业开发潜力巨大,是天然的合作伙伴。文章借助次区域经济合作理论和地缘政治经济学构建次区域粮食安全合作理论,就落实次区域粮食安全共同体的现实困境——复杂的内外环境,分析次区域合作的有利条件和挑战,提出了推动构筑次区域粮食安全合作命运共同体的可行路径。

不同情境下公共流域水资源动态一体化调控——以澜湄流域为例

从一体化视角出发针对不同的水文情境分析公共流域水资源调控能够应对复杂多变的气候变化。文章采用DPSIR模型构建流域水资源系统分析框架,并构建其系统动力学模型组从供需方面分析流域水资源系统的因果关系。以澜沧江−湄公河流域(文中简称澜湄流域)为例,运用系统动力学模型探究流域现在和未来的水资源供需情况,结合不同水文情景进行仿真分析,分析其演化过程和调控机制。结果显示:不同水文情景下流域内的水资源供需矛盾存在较大差异,结构性措施主要影响水资源的供给,非结构性措施主要影响水资源的需求。两种类型措施单独实施时都能够缓解流域内水资源短缺的压力,但对于较为极端的水文情景,流域未来仍会面临水资源短缺的压力。当结构性措施和非结构性措施同时实施时,流域内水资源的供给具有较大韧性,即使在较为极端的水文条件下仍然能够调节流域的水资源供需平衡,有利于流域内水资源的长期可持续发展。研究结果揭示了一体化视角下澜湄流域在不同水文情境下水资源的调控效果,以及各种调控措施对水资源供需的影响,将为澜湄流域水资源系统调控的联合行动奠定了基础。

澜湄区域合作中“区域”观念的错位及其影响

澜沧江—湄公河是中国与大陆东南亚国家共享的一条跨界河流。冷战后,以这条河流为地缘纽带建立的区域合作已超过30年。截至目前,该区域有九个多边合作制度的名称里含有“湄公河”字样,但这些合作制度所指涉的地理范围却不完全相同,形成了大湄公河次区域、湄公河上游与下游、湄公河六国、湄公河五国、澜沧江—湄公河区域等五类区域观念。这些各不相同但又同时存在的区域观念导致对这条河流及这个区域的称谓变得复杂和不稳定,并进一步影响到各国在澜湄区域合作中的“身份”认知。其中一些区域观念与澜沧江—湄公河的地缘纽带发生了错位,呈现出身份上将湄公河国家去中国化、议题上将湄公河事务泛中国化、价值导向上将湄公河合作“阵营化”的特征,可能在澜湄区域合作进程中产生身份认同偏差、合作制度竞合、地缘政治失稳等系统性影响。中国作为区域内国家,应主动参与澜湄区域观念的规范性建构,引导形成更加稳定、包容的区域合作秩序。

气象产品的广义联合偏差修正方法及其应用

卫星气象产品、气候模式预测数据通常与地面观测数据存在偏差,为保证数据的可靠性和合理性,需要对其进行偏差校正,但偏差校正过程往往受具体区域气象特征、方法本身假定等因素的影响,导致修正效果不佳。为此,本文提出一种广义联合偏差修正方法,相较于现有研究最常用的单变量QM修正方法以及固定多变量修正顺序的JBC修正方法,该方法充分考虑到流域尺度降水和气温双变量的时空相关性,并结合其对径流的主导作用对变量修正顺序进行动态调整,实现了QM法和JBC法的优势互补。在澜沧江-湄公河流域的应用表明:考虑降水、气温相关性可显著改善降水和温度极值的修正效果,尤其是5、6月份,修正后气象与实测数据的纳什系数提升了0.5以上;考虑气象要素的修正次序显著降低了修正后的降水和温度频率分布及均值偏差;利用修正后的气象数据驱动分布式水文模型时,部分月份的径流模拟精度提升了54.3%。

澜沧江-湄公河流域埃及伊蚊抗药性研究进展

埃及伊蚊起源于非洲,是登革热、寨卡病毒病、基孔肯雅热和黄热病等重要虫媒传染病的主要媒介。近年来,随着澜沧江-湄公河流域大量使用杀虫剂控制埃及伊蚊种群密度,埃及伊蚊对杀虫剂抗性程度不断增加。本文综述了澜沧江-湄公河流域有关区域埃及伊蚊对拟除虫菊酯、有机磷、氨基甲酸酯和有机氯杀虫剂抗药性的研究进展,为制定有效的埃及伊蚊控制策略提供参考。

基于CiteSpace的中国澜沧江―湄公河文献可视化研究

澜沧江—湄公河是亚洲最重要的国际河流之一,流经中国、泰国、老挝、缅甸、柬埔寨和越南6个国家,有约6千万人的生活与这条河流息息相关。国内关于澜沧江—湄公河的研究正处于稳步发展的阶段,以中国知网CNKI为文献研究的数据平台,检索2000―2023年澜沧江—湄公河的相关核心文献,运用Citespace软件对数据库进行计量可视化分析和综述。主要发现有:(1)从发文量及作者上看,澜沧江—湄公河研究关注度逐年波动上升,但作者之间缺乏合作;(2)从关键词共现、聚类分析上看,澜沧江—湄公河研究热点主要集中在全球气候变化下的澜沧江—湄公河变化和合作领域,研究的主题多样,但研究方法和实验过程需要进一步规范;(3)从关键词突现上看,目前的研究已跳出对澜沧江—湄公河的自然环境和水文生态的研究,澜湄合作机制和相关政策的研究受到了越来越多学者的关注。基于分析结果,最后提出了对未来澜沧江—湄公河研究前沿和趋势的思考与展望。