Water Systems and Global Change Group, Wageningen University, P.O. Box 47, 6700 AA Wageningen, the Netherlands.
Water Systems and Global Change Group, Wageningen University, P.O. Box 47, 6700 AA Wageningen, the Netherlands.
Sci Total Environ. 2019 Feb 1;649:601-609. doi: 10.1016/j.scitotenv.2018.08.160. Epub 2018 Aug 17.
The river flow regime and water resources are highly important for economic growths, flood security, and ecosystem dynamics in the Mekong basin - an important transboundary river basin in South East Asia. The river flow, although remains relatively unregulated, is expected to be increasingly perturbed by climate change and rapidly accelerating socioeconomic developments. Current understanding about hydrological changes under the combined impacts of these drivers, however, remains limited. This study presents projected hydrological changes caused by multiple drivers, namely climate change, large-scale hydropower developments, and irrigated land expansions by 2050s. We found that the future flow regime is highly susceptible to all considered drivers, shown by substantial changes in both annual and seasonal flow distribution. While hydropower developments exhibit limited impacts on annual total flows, climate change and irrigation expansions cause changes of +15% and -3% in annual flows, respectively. However, hydropower developments show the largest seasonal impacts characterized by higher dry season flows (up to +70%) and lower wet season flows (-15%). These strong seasonal impacts tend to outplay those of the other drivers, resulting in the overall hydrological change pattern of strong increases of the dry season flow (up to +160%); flow reduction in the first half of the wet season (up to -25%); and slight flow increase in the second half of the wet season (up to 40%). Furthermore, the cumulative impacts of all drivers cause substantial flow reductions during the early wet season (up to -25% in July), posing challenges for crop production and saltwater intrusion in the downstream Mekong Delta. Substantial flow changes and their consequences require careful considerations of future development activities, as well as timely adaptation to future changes.
湄公河流域的河川水流状况和水资源对该地区的经济增长、洪灾安全和生态系统动态都至关重要，湄公河是东南亚重要的跨界流域。尽管湄公河的水流状况基本保持自然状态，但预计其仍将受到气候变化和快速增长的社会经济发展的影响而日益不稳定。然而，目前对于这些驱动因素综合作用下的水文变化，人们的了解还很有限。本研究展示了到 2050 年代，由多种驱动因素（气候变化、大规模水电开发以及灌溉土地扩张）引起的水文变化预测情况。研究发现，未来的水流状况极易受到所有考虑因素的影响，表现在年际和季节性水流分布上都有明显变化。尽管水电开发对年总流量的影响有限，但气候变化和灌溉扩张分别导致年流量增加 15%和减少 3%。然而，水电开发对季节性变化的影响最大，表现为旱季流量增加（高达 70%）和雨季流量减少（最多减少 15%）。这些强烈的季节性影响往往超过其他驱动因素的影响，导致整体水文变化模式为旱季流量大幅增加（最多增加 160%）；雨季前半段流量减少（最多减少 25%）；雨季后半段流量略有增加（最多增加 40%）。此外，所有驱动因素的累积影响导致雨季前期流量大幅减少（7 月份最多减少 25%），这对下游湄公河三角洲的作物生产和咸水入侵构成挑战。水流的大幅变化及其后果需要对未来的发展活动进行仔细考虑，并及时适应未来的变化。
