华东师范大学学报(自然科学版) ›› 2024, Vol. 2024 ›› Issue (1): 90-103.doi: 10.3969/j.issn.1000-5641.2014.01.010

• 河口海岸生态安全研究 • 上一篇    下一篇

长江流域梯级水库夏末秋初蓄水对河口盐水入侵和淡水资源的影响

金智1, 朱建荣1,2,*(), 仇威1   

  1. 1. 华东师范大学 河口海岸学国家重点实验室, 上海 200241
    2. 上海水环境模拟与水生态修复工程技术研究中心, 上海 200233
  • 收稿日期:2023-02-14 接受日期:2023-03-29 出版日期:2024-01-25 发布日期:2024-01-23
  • 通讯作者: 朱建荣 E-mail:jrzhu@sklec.ecnu.edu.cn
  • 基金资助:
    国家自然科学基金(42276174); 国家重点研发计划(2022YFA1004404); 上海市科委社会发展科技攻关项目(22dz1202700)

Effects of cascade reservoirs in the Yangtze River Basin on estuarine saltwater intrusion and freshwater resources during late summer and early autumn

Zhi JIN1, Jianrong ZHU1,2,*(), Wei QIU1   

  1. 1. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China
    2. Shanghai Engineering Technology Research Center of Water Environment Simulation and Water Ecological Restoration, Shanghai 200233, China
  • Received:2023-02-14 Accepted:2023-03-29 Online:2024-01-25 Published:2024-01-23
  • Contact: Jianrong ZHU E-mail:jrzhu@sklec.ecnu.edu.cn

摘要:

流域大型梯级水库群, 夏末秋初蓄水, 来年枯季放水, 季节性改变了入海径流量, 会影响河口盐水入侵和淡水资源利用. 收集了长江流域大型梯级水库有效库容和南水北调工程跨流域调水的量值, 利用改进的河口海岸三维数值模式ECOM-si, 模拟和分析了长江流域重大工程对河口盐水入侵和淡水资源的影响. 截至2020年和2035年, 长江流域中上游已建和将建大型水库有效库容分别为706.11和943.88亿m3, 蓄水期9、10月间平均径流量分别减少13398和17909 m3/s. 基于大通实测水文站1950—2020年实测月平均径流量, 考虑截至2020年和2035年流域重大工程对径流量的调节, 给出了平均水文年和特枯水文年8—10月的月平均径流量. 数值模拟结果表明, 截至2020年和2035年流域梯级水库9—10月蓄水, 径流量下降, 导致盐水入侵加剧. 在平均水文年, 南支水源地4个水库9—10月所有时间均能取到淡水. 在特枯水文年, 9—10月东风西沙、太仓、陈行和青草沙水库取水口连续不宜取水天数截至2020年分别为28.75、24.99、29.63和37.47 d, 到2035年分别为46.53、44.18、47.56和50.75 d. 夏末秋初特枯和平均水文年情况下流域水库蓄水期间遇到强北风作用, 均会显著影响长江口水源地取水. 对于特枯水文年, 流域水库群应减少蓄水量, 甚至应该放水, 以保障长江口淡水资源的安全.

关键词: 流域水库群, 径流量, 长江河口, 盐水入侵, 数值模拟

Abstract:

Large cascade reservoirs in basins impound water in late summer and early autumn and release water in the dry season of the following year. These activities affect seasonal river discharge into the sea which, in turn, affects saltwater intrusion in estuaries and the utilization of freshwater resources. This study evaluated the effective storage capacity of large cascade reservoirs and the value of cross-basin water transfers by the South-to-North Water Transfer Project in the Yangtze River Basin. The estuarine and coastal three-dimensional numerical model ECOM-si was used to simulate and analyze the impact of major projects on estuarine saltwater intrusion and freshwater resources. In 2020, the effective storage capacity of large reservoirs built in the middle and upper reaches of the Yangtze River Basin was 70.611 billion cubic meters with a mean reduction in monthly river discharge of 13,398 m3/s during the storage period of September to October. By 2035, the completion of additional reservoirs in the basin will raise the total effective storage capacity of these reservoirs to 94.388 billion cubic meters and reduce the average monthly runoff by 17909 m3/s during the storage period. Using data on average monthly river discharge measured at the Datong Hydrological Station from 1950 to 2020, and by taking into account variations in river discharge by major projects in the basin, the average monthly river discharge from August to October from 2020 to 2035 in regular- and extra dry hydrological years was calculated. Numerical simulation results show that saltwater intrusion from September to October will increase due to impoundment in cascade reservoirs and decreased river discharge. During regular hydrological years, freshwater can be obtained from the four water reservoirs in the South Branch of the Yangtze River Estuary from September to October. However, water from the Dongfengxisha, Taicang, Chenhang, and Qingcaosha reservoirs is unsuitable for water intake during these months, particularly in extremely dry years. In 2020, the total number of consecutive days with unsuitable water intake from the four reservoirs was 28.75, 24.99, 29.63, and 37.47 days, respectively, and is predicted to rise to 46.53, 44.18, 47.56, and 50.75 days, respectively, in 2035. The impoundment of basin reservoirs in late summer and early autumn during average- and extremely dry hydrological years exposes them to strong northerly winds which can significantly decrease water intake. Basin reservoirs should reduce storage capacity and release water during extremely dry years to ensure the safety of freshwater resources in the Yangtze River Estuary.

Key words: basin reservoirs, river discharge, the Yangtze River Estuary, saltwater intrusion, numerical simulation

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