Vegetation dynamics regulate baseflow seasonal patterns of the Chaohe watershed in North China

Study region The Chaohe watershed is Beijing's primary potable water source. Study focus The initiation of ecological restoration (ER), combined with the rapid acceleration of climate change (CC), has precipitated severe water shortages in North China. The seasonal responses of baseflow (BF), pivotal for sustaining rivers' fundamental flow and ecological equilibrium, to ER and CC are poorly understood. This study provides a precise depiction of the seasonal variations in BF by leveraging multiple separation methodologies. By applying the BFAST algorithm and a comprehensive sensitivity analysis, we unveil the nuanced seasonal patterns of BF adjustments in reaction to ER and CC. New hydrological insights for the region Baseflow, primarily influenced by the wet season, constituted 64.21% of the annual aggregate. Considerable decreases in BF during the dry (−32.61%) and wet (−68.21%) seasons pose increasing threats to available water resources. The decrease in sub-surface runoff (−1.91 mm per decade) dominated the reduction of dry season BF. Indeed, vegetation regulated seasonal water distribution, maintaining the essential flow throughout the dry season. In the wet season, the reduction in BF acts as a supplemental water source to fulfill the escalating evapotranspiration needs due to afforestation and a drying climate. This study highlights the persistent hydrological consequences of ER and CC on water resources, emphasizing the crucial function of vegetation in baseflow, a key component for ecological restoration and water resource management in water-limited areas.