Hydrological model-driven framework for small and medium-sized reservoir cluster's impact on flood and low flows

Study region The southeastern coast of China. Study focus The impacts of small and medium sized reservoir cluster (SMRC) on flood and low flows have not been well investigated due to a lack of observed data. This study proposes an integrated framework for addressing the impacts of SMRC in the southeastern coast of China, using the Soil and Water Assessment Tool (SWAT) model. Within this framework, effects of climate variability, land use change, and SMRC regulation on daily flows were isolated. The response characteristics and mechanisms of flood and low flows to SMRC regulation were revealed. New hydrological insights for the region (1) The SMRC regulation not only reduced flood flows (decreased by 4.77%-37.61%), but also reduced low flows (decreased by 10.57%-22.4%). (2) Regarding the contribution of driving factors to flow changes, SMRC regulation contributed more to low-flow variations (41%-53.6%) than to flood-flow variations (10.9%-30.5%). Moreover, the contribution rate increased as the time scale shortened. (3) As larger cumulative storage capacities led to greater flood and low flow volume changes. (4) The integrated framework proposed in this study is applicable to revealing the impact of SMRC regulation on flood and low flows, and can provide a scientific reference for conducting related research in other basins.