Li Yunliang, Tan Zhiqiang, Zhang Qi, Liu Xinggen, Chen Jing, Yao Jing
Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Postal address: 73 East Beijing Road, Nanjing, 210008, China.
Hohai University, Postal address: 1 Xikang Road, Nanjing, 210098, China; Hydrological Bureau of Jiangxi Province, Postal address: 1499 Yanjiangnan Road, Nanchang, 330002, China.
Water Res. 2021 May 1;195:117005. doi: 10.1016/j.watres.2021.117005. Epub 2021 Mar 3.
Recent years, the hydrological connectivity has gained popularity in various research fields, however, its definition and threshold effects at a system scale have not received adequate attention. The current research proposes a promising framework to refine the concept of surface hydrological connectivity by combining hydrodynamic modeling experiments, threshold effects and geostatistical connectivity analysis, exemplified by the flood-pulse-influenced Poyang Lake floodplain system (China). To enhance the inherent linkage between hydrological connectivity and eco-environments, total connectivity (TC), general connectivity (GC), and effective connectivity (EC) were proposed to refine the metrics of hydrological connectivity. The results show that substantial differences between the three connectivity metrics are observed for all target directions, demonstrating that the joint role of water depth and flow velocity may produce more dynamic and complex influences on EC than the other two metrics of TC and GC. Topographically, the connectivity objects/areas within the flood pulse system reveal that the floodplain is a more sensitive area than the lake's main flow channels under different connectivity conditions. The modelling experimental studies show that variations in water depth thresholds are more likely to have a strong effect on connectivity for the dry, rising, and falling limbs, rather than the flooding period, while the flow velocity may exert an opposite threshold effect. The lake-floodplain system is characterized by a dynamic threshold behavior, with seasonally varying water depth and velocity thresholds. This study highlights the importance of redefined connectivity concept for facilitating scientific communication by combining hydrodynamic thresholds and offering recommendations for future connectivity assessments using our proposed metrics of TC, GC, and EC.
近年来，水文连通性在各个研究领域中受到了广泛关注，然而，其在系统尺度上的定义和阈值效应尚未得到充分重视。当前的研究提出了一个有前景的框架，通过结合水动力模型实验、阈值效应和地统计连通性分析来完善地表水文学连通性的概念，以受洪水脉冲影响的鄱阳湖洪泛平原系统（中国）为例进行说明。为了加强水文连通性与生态环境之间的内在联系，提出了总连通性（TC）、一般连通性（GC）和有效连通性（EC）来完善水文连通性的度量指标。结果表明，在所有目标方向上，三种连通性度量指标之间都存在显著差异，这表明水深和流速的共同作用可能对有效连通性产生比总连通性和一般连通性这另外两个指标更具动态性和复杂性的影响。在地形方面，洪水脉冲系统内的连通性对象/区域表明，在不同的连通性条件下，洪泛平原比湖泊的主要河道是更敏感的区域。模型实验研究表明，水深阈值的变化对枯水期、涨水期和落水期的连通性影响可能比洪水期更强，而流速可能产生相反的阈值效应。湖泊 - 洪泛平原系统具有动态阈值行为，其水深和流速阈值随季节变化。本研究强调了重新定义连通性概念对于促进科学交流的重要性，通过结合水动力阈值，并使用我们提出的总连通性、一般连通性和有效连通性指标为未来的连通性评估提供建议。
