The Impacts of Hydrology and Climate on Hydrological Connectivity in a Complex River-Lake Floodplain System Based on High Spatiotemporal Resolution Images

The drivers that determine the hydrological connectivity (HC) are complex and interrelated, and disentangling this complexity will improve the administration of the river-lake interconnection system. Dongting Lake, as a typical river-lake interconnected system, is freely connected with the Yangtze River and their HC plays a major role in keeping the system healthy. Climate, hydrology, and anthropogenic activities are associated with the HC. In this study, hydrological drivers were divided into the total flow of three inlets (T-flow) and the total flow of four tributaries (F-flow). To elucidate the HC of the Dongting Lake, HC was calculated by geostatistical methods in association with Sentinel-2 remote sensing images. Then, the structural equation model (SEM) was used to quantify the impacts of hydrology (F-flow, and T-flow) and meteorology (precipitation, evaporation, and temperature) on HC. The geostatistical analysis results demonstrated that the HC showed apparent seasonal change. For East and West Dongting Lake, the dominant element was north-south hydrological connectivity (N-S HC), and the restricted was west-east hydrological connectivity (W-E HC), but the dominant element was E-W HC and the restricted was N-S HC in South Dongting Lake. The results of SEM showed that N-S HC was mainly explained by T-flow (r = 0.49, p < 0.001) and F-flow (r = 0.28, p < 0.05). T-flow, temperature (r = 0.33, p < 0.05), and F-flow explained E-W HC. The finding of this work supports the management of both the Dongting Lake floodplain and other similar river-lake floodplain systems.