Impact of Reservoir Construction on Downstream River Flood Control Safety

XU Shiming; ZHANG Zhiqian

doi:10.3969/j.issn.1004-7328.2025.12.009

Abstract：To clarify the comprehensive impact of reservoir construction with non-flood control functions on the flood safety of downstream river channels,a water supply-type reservoir on the Bukuotai River in Emin County,Xinjiang,was selected as the research object.It systematically analyzes the downstream flood discharge response mechanisms under three typical scenarios:the construction period,normal operation period,and dam breach flood.Through hydrological data analysis,HEC-RAS hydraulic modeling,and dam breach flood progression calculations,the study quantitatively examines flood characteristic parameters,changes in river hydraulic elements,and potential risk losses under different scenarios.The results indicate that the diversion scheme using a 5-year flood standard for earth-rock cofferdams during the construction period is reasonable and has minimal impact on downstream areas.During normal operation,the reservoir effectively mitigates flood peaks and delays flood surges,resulting in a maximum reduction of 0.08m in flood levels and a maximum decrease of 1.11m/s in flow velocity for the downstream river section.Additionally,the sediment concentration in the outflowing water is reduced,with no adverse effects on river discharge.Under extreme dam breach conditions,the instantaneous full breach generates a peak flow of 84,526 m³/s,which attenuates to 9,689 m³/s by the time it reaches the river outlet.Due to the constraints of the valley terrain and the infiltration effects of downstream depressions,the flood impact range and intensity remain controllable,with no significant protected targets at risk.The findings provide technical references and practical support for flood safety assessments of similar single-function reservoir projects.