Impacts of Anthropogenic Climate Change and Vegetation Variations on Global Changes in Baseflow and Stormflow

Abstract

Comprehending the causal relationships between shifting climatic patterns, dynamic vegetation cover, and altered hydrological cycles constitutes a fundamental prerequisite for developing adaptive strategies in water resources governance. We analyze changes in baseflow (BF) and stormflow (SF) in 3,388 watersheds globally in the response to changes in precipitation characteristics, vegetation (Normalized Difference Vegetation Index, NDVI), temperature, potential evapotranspiration, and the aridity index from 1982 to 2016, based on Random Forest Model simulations and Shapley Additive Explanations. We also evaluate the effects of anthropogenic climate change on changes in baseflow index (BFI, the ratio of baseflow to total streamflow) using the signal-to-noise ratio (SNR) method applied to multi-model simulations from ISIMIP2b. Results show that the BF and SF in the majority of watersheds show consistent trends, but they also show the opposite trends in specific seasons. Over 60% of watersheds in the Northern Hemisphere experienced a decrease in BF contribution to the total streamflow during the June-July-August season. Minimum temperature and NDVI are the most important factors influencing changes in BF and SF. Minimum and maximum temperature, precipitation seasonality, and precipitation intensity show negative effects on the BF, and the impact of vegetation on the BFI varies from region to region. The contribution of BF to the total streamflow decreases significantly at the global scale under the impact of anthropogenic climate change, according to the SNR analysis. The interaction of climate and vegetation changes on changes in BF and SF should take into account to regional adaptation of climate change for the utilization of groundwater and surface water resources.