Effect of wetland hydrological connectivity on runoff based on a basin comparison

Hydrological connectivity is of great significance to the protection of wetlands and the rational development of water resources. Climate change and overdevelopment have led to the reduction of the Zoige wetland area, the destruction of its ecosystem structure, and the severe degradation of wetland hydrological connectivity. This study proposes an analysis framework to explore the impact of hydrological connectivity on runoff based on the dynamic prediction of wetland spatial patterns and the quantification of wetland hydrological connectivity and nonlinear fitting; the Zoige wetland was selected for application and verification. Under the ecological protection scenario (Plan1), the wetland experienced an expansion of meadow wetland (MW); under the natural development scenario (Plan2), the degradation of shallow wetland (SW) is the most significant. The optimal threshold distances (TDs) for studying the hydrological connectivity in the Hei River basin (HRB) and Bai River basin (BRB) were 1200 m and 1800 m, respectively. The hydrological connectivity of the HRB was significantly greater, with a value that was approximately 30–50 times that of the BRB in the same year. The IIC and PC of the two basins gradually decreased during the historical period and showed increasing and decreasing trends under the Plan1 and Plan2 scenarios, respectively. The effect of wetland hydrological connectivity on runoff was significantly different in the two basins; wetlands developed extensively in the HRB, and connectivity had an inhibitory effect on the runoff and the runoff-generating efficiency of precipitation, while the wetland was even more fragmented in the BRB, and the increase in connectivity promoted the generation of runoff. Because biodiversity is sensitive to change, the patches in the middle reaches of the HRB and the lower reaches of the BRB are the areas that should receive the highest wetland protection priority in the future.