Hydrologic balance and inundation dynamics of Southeast Asia's largest inland lake altered by hydropower dams in the Mekong River basin
Hydrologic balance and inundation dynamics of Southeast Asia's largest inland lake altered by hydropower dams in the Mekong River basin
复制标题
湄公河流域水电大坝改变东南亚最大内陆湖的水文平衡和淹没动态
DOI：
10.1016/j.scitotenv.2022.154833
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发表时间：
2022
影响因子：
9.8
通讯作者：
Du Bui, Duong
中科院分区：
文献类型：
--
作者：
Dang, Huy;Pokhrel, Yadu;Shin, Sanghoon;Stelly, Jac;Ahlquist, Daniel;Du Bui, Duong
内陆湖泊日益受到气候变化和人类活动的影响，造成了前所未有的环境后果。柬埔寨的TonléSAP湖(TSL)是东南亚最大的内陆湖，在许多快速变化的湖泊中，由于气候变化和湄公河流域(MRB)大坝建设的综合影响，该湖正面临水流变化和洪水动态的日益威胁。虽然以前的研究已经研究了开放水域最近变化的潜在原因，但缺乏对由于自然气候变化和大坝运行而导致的湖泊水文平衡和洪水动态变化的机械量化。在这里，我们使用了一个包括MRB主要大坝的水文-水动力模拟系统，我们表明，虽然气候变化一直是湖泊水量平衡年代际变化的关键驱动因素，但湄公河大坝的运行对湄公河洪水脉冲、TonléSAP河的倒流和TSL的淹没动态产生了越来越大的影响。大坝对湄公河洪峰流量的抑制作用从1979-2009年间的1-2%增加到2010年代的~7%，导致湄公河流入TSL的洪峰也发生了类似的变化。更重要的是，在2010年代，这些大坝导致TSL的年流入水量减少了10%-25%，并将湖泊周边的年洪水持续时间缩短了多达15天。此外，在2010年代的8月(4月)，季节性淹没面积大幅减少(增加)了~245平方公里或~3%(~270平方公里或~6%)。这些结果表明，湄公河大坝已经对TSL的水文平衡和淹没动力学造成了实质性的变化。我们的发现为改进跨界水管理和决策提供了关键的见解，因为人们越来越担心MRB中大型水坝的不利影响。
Inland lakes have been increasingly impacted by climate change and human activities, leading to unprecedented environmental consequences. Among many rapidly changing lakes is the Tonlé Sap Lake (TSL) in Cambodia—Southeast Asia's largest inland lake—which is under growing threats from altered flows and inundation dynamics due to compounding effects of climate change and dam construction in the Mekong River basin (MRB). While previous studies have examined the potential causes of recent changes in open water areas, a mechanistic quantification of the lake's shifting hydrologic balance and inundation dynamics due to natural climate variability and dam operations is lacking. Here, using a hydrological-hydrodynamic modeling system that includes the major dams in the MRB, we show that while climate variability has been a key driver of inter-decadal variabilities in the lake's water balance, the operation of Mekong dams has exerted a growing influence—especially after 2010—on the Mekong flood pulse, Tonlé Sap River's flow reversal, and the TSL's inundation dynamics. The dam-induced dampening of the Mekong's peak discharge increased from 1–2% during 1979–2009 to ~7% in the 2010s, causing comparable alterations in the peak of inflow from the Mekong into TSL. More crucially, during the 2010s, the dams caused a reduction in annual inflow volume into TSL by 10–25% and shortened the annual inundation duration by up to 15 days in the lake's periphery. Further, seasonally inundated areas decreased (increased) most substantially by ~245 km2or ~3% (~270 km2or ~6%) in August (April) during the 2010s. These results demonstrate that Mekong dams have already caused substantial alterations in the hydrologic balance and inundation dynamics of the TSL. Our findings offer critical insights relevant for improved transboundary water management and decision making in light of growing concerns about the adverse impacts of large dams in the MRB.