Li Yunliang, Cao Sijia, Yu Lina, Yao Jing, Lu Jianzhong
Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing, 210008, PR China.
College of Geosciences and Engineering, North China University of Water Resources and Electric Power, 36 Beihuan Road, Zhengzhou, 450045, PR China.
J Environ Manage. 2023 Jun 15;336:117654. doi: 10.1016/j.jenvman.2023.117654. Epub 2023 Mar 2.
Dam-induced hydrological alterations and eco-environmental impacts have significant implications, however, these concern issues in large floodplain systems are less well understood. The present study shows a first attempt to adopt a quasi-three-dimensional groundwater flow modeling FEFLOW (Finite Element subsurface FLOW system) to investigate the influences of a proposed hydraulic dam on groundwater dynamics in the largest floodplain lake of the Yangtze River basin (Poyang Lake, China). The FEFLOW model was successfully constructed and has the ability to represent the hydrodynamics of floodplain groundwater flow. Model simulations indicate that, in general, the dam is likely to increase the groundwater levels across the floodplain during different hydrological phases. The responses of floodplain groundwater levels to the dam during the dry and recession phases are stronger (∼2-3 m) than the rising and flooding phases (<2 m). Under the natural condition, the floodplain groundwater may recharge the lake during the dry and recession phases, and discharge the lake during the rising and flooding phases. However, the dam regulation may alter the natural recharge-discharge patterns, forming a generally gaining condition of the floodplain groundwater. The proposed dam is most likely to reduce the groundwater flow velocity (∼<1 m/d) relative to the natural condition (up to 2 m/d) during different hydrological phases, and it may also alter the floodplain groundwater flow direction during the dry and recession phases. Additionally, the floodplain groundwater system is mainly characterized by losing state (-4.5 × 10 m/yr) under the natural condition, while the dam-induced groundwater system exhibits an overall gaining state (9.8 × 10 m/yr). The current research findings contribute to future water resources assessment and management by providing a foundation for assessing associated eco-environmental changes of the large lake-floodplain system.
大坝引发的水文变化及其对生态环境的影响具有重大意义，然而，对于大型洪泛区系统中的这些相关问题，人们的了解还比较有限。本研究首次尝试采用准三维地下水流模拟软件FEFLOW（有限元地下水流系统），来探究拟建水利大坝对长江流域最大洪泛区湖泊（中国鄱阳湖）地下水动态的影响。FEFLOW模型成功构建，能够呈现洪泛区地下水流的水动力特性。模型模拟结果表明，总体而言，大坝可能会使不同水文阶段整个洪泛区的地下水位上升。洪泛区地下水位在枯水期和退水期对大坝的响应（约2 - 3米）比涨水期和洪水期更强（小于2米）。在自然条件下，洪泛区地下水在枯水期和退水期可能会补给湖泊，而在涨水期和洪水期则会向湖泊排水。然而，大坝调节可能会改变自然的补排模式，使洪泛区地下水总体处于补给状态。拟建大坝很可能会使不同水文阶段的地下水流速相对于自然条件（高达2米/天）降低（约小于1米/天），并且在枯水期和退水期还可能改变洪泛区地下水流向。此外，自然条件下洪泛区地下水系统主要处于排泄状态（-4.5×10米/年），而大坝引发的地下水系统则呈现总体补给状态（9.8×10米/年）。当前的研究结果为评估大型湖泊 - 洪泛区系统相关生态环境变化提供了基础，有助于未来的水资源评估和管理。
