Contribution of changes in vegetation composition and climate variability on streamflow across the global watersheds

Abstract

Vegetation and climate play critical roles in the hydrological cycle as vital components of the earth system. Understanding the impacts of changes in vegetation composition and climate on hydrological processes is essential for water balance and sustainable water resource management. We analyzed the effects of changes in vegetation composition and climate variability on streamflow changes in 3434 global watersheds from 2003 to 2016 using the Budyko framework. We found that ignoring changes in terrestrial water storage would result in large errors in the influence of landscape changes on streamflow changes. The sensitivity of streamflow changes to climate seasonality index (CSI), precipitation seasonality index (PSI), total vegetation coverage (M), tree coverage (MT), and non-tree coverage (MNT) varied in different regions. Effective precipitation (Pe), potential evapotranspiration (PET), CSI, PSI, M, MT, and MNT changes were the dominant factor in streamflow changes for 64.8%, 3.0%, 5.1%, 4.1%, 9.8%, 7.7%, 5.6% of global watersheds, respectively. Attributing streamflow changes showed that the effects of MT and MNT on streamflow changes were mutually reinforcing in most basins. The influence of vegetation composition on streamflow changes was greater in semi-humid and arid regions than in humid regions. This research quantified the impacts of vegetation composition changes and climate change on streamflow changes worldwide and could clarify the hydrological responses to changing environments.