Landscape- and climate change-induced hydrological alterations in the typically urbanized Beiyun River basin, Beijing, China

Landscapes in urbanized regions have experienced considerable changes in recent decades, and had a growing number of negative effects on hydrological processes. However, it is not well understood to what extent the combined and individual landscape and climate factors have altered hydrological processes in such areas. Using Beiyun River in Beijing as a case, we assessed hydrological responses quantitatively based on the Water and Energy Transfer between Soil, Plants and Atmosphere model (WetSpa extension). The results indicated that landscape patterns varied greatly from 2000 to 2012, which was exhibited primarily by the encroachment of built-up land on cropland. The landscape indices selected showed that the landscapes are prone to be disaggregated, fragmented, and complicated due to urbanization. In addition, the WetSpa model is available to simulate daily hydrological processes after calibration with model bias, model confidence and Nash–Sutcliffe efficiency of 18%, 0.71 and 0.84, respectively, and validation with correlation coefficient of 0.81. The model output revealed that the combined effects of landscape pattern change and climate variations increased total runoff and daily active groundwater storage. Among different sub-catchments, the Shahe sub-catchment upstream and Fenggangjianhe sub-catchment downstream had higher discharges, with increasing trends from 2000 to 2012. Compared with period 1 (2000–2005) as the reference, the annual average runoff during period 2 (2006–2011) and period 3 (2012–2016) increased 16.5 mm and 77.5 mm and the daily groundwater storage increased 71.6 mm and 47.3 mm through the combined effects of landscape and climate change. In period 2, the individual climate change had a positive effect on runoff with the contribution rate of 120.6% while landscape variation had a negative effect with the rate of − 20.6%. In period 3, they both had positive effects on runoff with the contribution rates of 93.6% and 6.4%, respectively. This study has practical significance for evaluation of the influence of urbanization on the hydrological processes and future water resource management.