*Article* **Long-Term Baseflow Responses to Projected Climate Change in the Weihe River Basin, Loess Plateau, China**

**Junlong Zhang 1, Panpan Zhao 2,\*, Yongqiang Zhang 3, Lei Cheng 4,5, Jinxi Song 6, Guobin Fu 7, Yetang Wang 1, Qiang Liu 8, Shixuan Lyu 1,9, Shanzhong Qi 1, Chenlu Huang 6, Mingwei Ma <sup>2</sup> and Guotao Zhang <sup>10</sup>**


**Abstract:** Climate change is a significant force influencing catchment hydrological processes, such as baseflow, i.e., the contribution of delayed pathways to streamflow in drought periods and is associated with catchment drought propagation. The Weihe River Basin is a typical arid and semiarid catchment on the Loess Plateau in northwest China. Baseflow plays a fundamental role in the provision of water and environmental functions at the catchment scale. However, the baseflow variability in the projected climate change is not well understood. In this study, forcing meteorological data were derived from two climate scenarios (RCP4.5 and RCP8.5) of three representative general circulation models (CSIRO-Mk3-6-0, MIROC5, and FGOALSg2) in CMIP5 and then were used as inputs in the Soil and Water Assessment Tool (SWAT) hydrological model to simulate future streamflow. Finally, a well-revised baseflow separation method was implemented to estimate the baseflow to investigate long-term (historical (1960–2012) and future (2010–2054) periods) baseflow variability patterns. We found (1) that baseflow showed a decreasing trend in some simulations of future climatic conditions but not in all scenarios (*p* < 0.05), (2) that the contribution of baseflow to streamflow (i.e., baseflow index) amounted to approximately 45%, with a slightly increasing trend (*p* ≤ 0.001), and (3) an increased frequency of severe hydrological drought events in the future (2041–2053) due to baseflows much lower than current annual averages. This study benefits the scientific management of water resources in regional development and provides references for the semi-arid or water-limited catchments.

**Keywords:** baseflow; Weihe River Basin; Loess Plateau; climate change; General Circulation Models
