Evolutionary characteristics and attributions of ecological drought in river: A case study in the Yellow River Basin

Study Region Yellow River Basin (YRB), China. Study focus The ecohydrological variables of the YRB vary significantly under a changing environment. Therefore, it is crucial to explore that how climate change and human activities alter the evolution of ecological drought. In this study, change-point and trend-analysis were employed to identify the non-stationary characteristics of hydro-meteorological variables in the YRB. Then, the natural streamflow series was recreated using variable infiltration capacity (VIC) model and the most suitable ecological streamflow (MSES) was calculated through the non-parametric kernel density estimation (KDE) function. Finally, the impacts of climate change and human activity to the evolution on ecological drought in river were quantified. New Hydrological Insights for the Region Most of change points of streamflow series across the YRB appeared in 1985 and 2002. Then, baseline (1961–1985) and two change periods (1986–2002 and 2003–2020) were defined according to the change points. Spatially, climate change mitigated upstream ecological drought while human activities mainly affected those at downstream. The contribution of human influence on the ecological drought in river roughly increased gradually from upstream to downstream. In change period Ⅱ, from Toudaoguai to Huayuankou, the rates are 87 %, 88 %, 99 %, 102 %, respectively. Overall, this study explored the driving mechanisms of ecological drought in river from the perspective of climate change and human activities, thus providing a theoretical basis for watershed ecological sustainability. • An “observation-simulation” framework was proposed to attribute ecological drought. • The suitable ecological streamflow was calculated via kernel density estimation. • Impacts of climate change and human activity on ecological drought were quantified.