Abstract: Upstream flow control is an effective way to allocate downstream diversion risk in construction of
cascade hydropower stations. Aiming at evaluation on the benefit of upstream flow control measure, this
study systematically examines the generation benefit of upstream stations and the downstream stations under
construction influenced by operation transformation in these upstream stations, focusing on the upstream
stations and the downstream construction diversion. We explore the impact of flow control on diversion
standards, construction progress, and flood safety, from a perspective of the construction diversion system
and by comparison with that in free discharge condition. With consideration of all these effects,
comprehensive benefits of the upstream flow control measure are calculated, and economic feasibility of a
diversion risk distribution method with upstream flow control is quantitatively evaluated according to cost
and benefit by taking loss in power generation as costs of flow control and selecting benefit-cost ratio as
evaluation criteria. Anumerical example of risk analysis shows that the method is feasible and effective.