Refining the concept of hydrological connectivity for large floodplain systems: Framework and implications for eco-environmental assessments. (1st May 2021)

• Record Type: Journal Article
• Authors: Li, Yunliang; Tan, Zhiqiang; Zhang, Qi; Liu, Xinggen; Chen, Jing; Yao, Jing
• Is Part Of: Water research. Volume 195(2021)
• Publication Date: 2021-05-01
• Subjects: Hydrological connectivity -- Threshold effect -- Hydrodynamic model -- Floodplain lake -- Connectivity assessment -- Ecological and environmental goals; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2021.117005
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: Concept of hydrological connectivity is refined using hydrodynamic thresholds. Total, general, and effective connectivity were proposed to consider eco-environmental implications. Seasonally dynamic threshold behavior is found in flood-pulse-influenced systems. Thresholds of water depth and velocity may play a cumulative or compensatory role on connectivity. Proposed connectivity metrics provide an alternative strategy for assessment applications. ABSTRACT: 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. Graphic Abstract: Image, graphical abstract