Unraveling the impacts of river network connectivity on ecological quality dynamics at a basin scale in the Greater Bay Area

Abstract

An unobstructed river system ensures the safety of hydrological regulation and storage, protects critical habitats, facilitates the movement of wildlife, and enhances soil and water environments. The connectivity of this river network fundamentally influences regional water resource management, the hydrological cycle, landscape patterns, ecological health, and socio-economic development. It can be foreseen that the river network connectivity is highly correlated with the ecological quality. In this study we measured the temporal and spatial variability of ecological quality as reflected by remote sensing ecological indices (RSEI) and measure the RNC as total 7 indices including river importance of river density (Dr), water surface ratio (Wr), network connectivity (γ), edge-node ratio (β) and node importance indices of PageRank (PG_R), in-closeness centrality (In_C) and betweenness centrality (BC) and generated at the subbasin scale. The result of this study demonstrated that RNC is not the control factor of the RSEI value, but the RNC will affect the stable of the basins’ RSEI value from 2000-2021. Although the 7 RNC indices haven’t shown obvious correlation with the RSEI, the river density (Dr), the water surface ratio (Wr) and the PageRank (PG_R) significantly passively influence the standard deviation of the RSEI (EI_STD), which means the 3 factors affect the temporal variability of subbasin RSEIs. Basins with higher value of river density (Dr), water surface ratio (Wr) and water surface ratio (Wr) were associated with increased subbasin RSEI variability.