Evolution and attribution analysis of baseflow on both banks of the Wei River basin

Baseflow is a crucial component of river runoff and river ecological health. Reliable baseflow separation and attribution of its drivers are important for sustainable water management in arid and semi-arid basins. We analyzed 18 tributaries on the north and south banks of the Wei River basin (2006–2020). Nine baseflow separation methods were compared, and performance was evaluated using NSE and KGE. We then assessed trends of hydro-meteorological variables and quantified the contributions of climate change and human activities to baseflow changes. Among the nine methods, F2 performed best, with the highest mean NSE (0.73) and mean KGE (0.76) across the 18 sites. Baseflow on both banks showed a non-significant increasing trend (P > 0.05). Precipitation significantly affected baseflow on both banks, and potential evapotranspiration also had a significant influence on the south bank (P < 0.05). Attributions differed spatially: on the south bank, baseflow changes at Laoyukou, Dayu, and Luolicun were mainly climatedriven (63.26%, 58.81%, and 74.55%), while on the north bank only Fenggeling and Qianyang were mainly climate-driven (72.29% and 53.92%); most other stations were mainly influenced by human activities. The optimal separation method and the contrasting attributions between banks highlight strong spatial heterogeneity in baseflow controls and underscore the importance of considering both climatic drivers and human activities in basin management.