Identifying the Impacts of Land Use Landscape Pattern and Climate Changes on Streamflow From Past to Future

Identifying the individual and combined hydrological response of land use landscape pattern and climate changes is the key to effectively managing the ecohydrological balance of regions. However, the nonlinearity, effect size, and multiple causalities limit a causal investigation. Therefore, this study established a comprehensive methodology framework to analyze the impact and attribution of landscape pattern and climate changes on streamflow events in five basins in Beijing. Future climate projections were based on three general circulation models (GCMs) under two shared socioeconomic pathways (SSPs). Additionally, the landscape pattern in 2035 under a natural development scenario was simulated by the patch-generating land use simulation (PLUS). The Soil and Water Assessment Tool (SWAT) was applied to evaluate the streamflow spatial and temporal dynamics over the period 2005–2035 with multiple scenarios. A bootstrapping nonlinear regression analysis and boosted regression tree model (BRT) were used to analyze the individual effects and the combined attribution of landscape pattern and climate changes on streamflow, respectively. Results indicated that in the future, the overall streamflow in the Beijing basin would decrease, with a slightly reduced peak streamflow in most basins in the summer and a significant increase in the autumn and winter. The nonlinear quadratic regression more effectively explained the impact of landscape pattern and climate changes on streamflow. The trends in the streamflow change depended on where the relationship curve was in relation to the threshold. In addition, the impacts of landscape pattern and climate changes on streamflow were not isolated but were joint. They presented a nonlinear, non-uniform, and coupling relationship. Except for the YongDing River Basin, the annual streamflow change was influenced more by the landscape pattern. The dominant factors and the critical pair interactions varied from basin to basin. Our findings have implications for landscape planners and managers for optimizing ecohydrological functions and promoting sustainable development