Assessment of Ecological Flow and Attribution of Eco-flow Indicators in Small Hydropower Rivers
As one of the crucial strategies to achieve the"dual-carbon"goal in China,green small hydropower can provide economic bene-fits in small to medium-sized river basins.However,it will also impacts the ecohydrological processes of the basin,thus limiting the sustain-able development of small hydropower river ecosystems.Taking Bin River Basin as an example,the SWAT model was applied to reconstruct the runoff process in different periods.The ecological flow was quantified temporal and spatial terms based on the ecological flow process line group.The change laws of ecological runoff indicators in different scenarios were compared,and the contribution of human activities and cli-mate change to ecological profit and loss was quantitatively revealed.The comprehensive analysis revealed several critical findings:①There were significant spatiotemporal differences in ecological flow distribution within the Bin River Basin.Compared to the baseline period,cli-mate change and human activities are not conducive to ensuring the ecological flow in the basin.The median value of ecological flow assur-ance rate has decreased by nearly 7%under the influence of climate change.When compounded with the impact of human activities,there was a cumulative decrease of 17.74%in the median value of ecological flow assurance rate.Especially,the ecological water demand was se-vere during the flood season and its culmination.Hence,the implementation of seasonally restricted operational protocols for small-scale hy-dropower facilities arises as a prospective strategy for ameliorating this ecological challenge in future periods.②On an annual scale,climate change predominantly led to a reduction in eco-surplus,with the most significant decrease occurring in the summer(p<0.05).In contrast,human activities primarily caused an increase in eco-deficit,especially during the autumn and winter seasons(p<0.10).③There was a no-table consistency between eco-surplus and precipitation anomalies,with correlation coefficients consistently exceeding 0.50.However,the correlation between eco-deficit and precipitation anomalies was weaker,particularly during the autumn and winter seasons,where their cor-relation coefficients often fall below 0.30.④Regarding annual variability,human activities have consistently accounted for relative contribu-tions exceeding 80%to the changes in eco-flow over the all periods.Excessive human interference was identified as the primary cause of eco-water scarcity in the Bin River basin.The research results provide reference for the health management of small hydropower rivers under the changing environment.