Detecting and attributing the changes in baseflow in China’s Loess Plateau

Abstract

Baseflow plays an important role in sustaining the ecosystem during dry seasons or in arid regions, and its spatiotemporal variations greatly influence the stability of ecosystem. Because of climate change and the revegetation project, the streamflow has been reported to significantly decrease in past decades in China’s Loess Plateau (CLP); however, the changes in streamflow components have not been fully investigated. The objective of this study is thus to detect and attribute the changes in baseflow in the CLP using data of 55 hydrological stations for 1956–1990 and 2001–2019. The geographic detector, correlation analysis and elasticity coefficient methods were employed to qualitatively and quantitively analyze the influence of various factors on baseflow. The baseflow accounts for 35%-76% of streamflow. The baseflow in 85% of hydrological stations decreased by >10%, while the baseflow index (BFI) of 82% hydrological stations showed an upward trend. Precipitation and hydrogeological condition (e.g., loess thickness) were likely to dominate the spatial heterogeneity of baseflow, while the potential evapotranspiration, population, sub-surface runoff, NDVI and soil water were responsible for the decrease in baseflow with contributions of 27%, 21%, 17%, 16% and 16%, respectively. The consistence or inconsistence between baseflow and BFI as well as their relations to environmental changes provide new insights into the changes in hydrological processes.