To reveal the response characteristics of reservoir group operation to the non-stationary inflow runoff and achieve adaptive reservoir operation, the reservoir group in the Xijiang River Basin was used as a research object. An evolutionary multi-objective direct policy search algorithm was employed to construct a multi-objective optimization operation model for the reservoir group, and the optimal solutions that balance multiple objectives of power generation, ecology, and water level were obtained. Under both stationary and non-stationary runoff conditions, the sensitivity analysis method was used to re-evaluate the optimal solutions, and further to reveal the sensitivity response characteristics of operation objectives to inflow runoff. The results indicate that there are significant trade-off relationships between the rates of ecological water shortage and water level risk at the Wuzhou station and the average output of the reservoir group in the Xijiang River Basin. The sensitivity of operation objectives to inflow runoff does not show significant differences among different optimal solutions, but it is more responsive to non-stationary runoff. The wet-dry variations in runoff under non-stationary conditions are more pronounced, which to some extent enhances the average output of the cascade reservoir group, while also leading to higher rates of ecological water shortage and water level risks at the Wuzhou station.

To mitigate the impacts of renewable energy accommodation on the river flow regime and ecological integrity in scheduling of hydropower stations on the upper Yellow River, a multi-energy complementary system ecological scheduling model was established with the objectives of minimizing variations in river flow regime, maximizing power generation of hydropower stations, and ensuring the highest stability of generation output. A multi-objective evolutionary algorithm was employed to explore the balance among the generation output of the multi-energy complementary system, renewable energy accommodation, and ecosystem protection of rivers. The results indicate a clear competitive relationship between power generation of hydropower stations and river ecosystem protection objectives. The larger the fluctuation in generation output of the multi-energy complementary system, the greater the power generation of hydropower stations and the larger the variation in river flow regime. Moreover, the larger the inflow volume, the smaller the impacts of ecological scheduling of hydropower stations on river flow regime, and the impacts are mainly concentrated on the indicators, including the numbers of annual occurrences of high/low flow pulses and the average increase/decrease rate of flow. In the scheduling results with maximum power generation in dry years, the indicators of the number of annual occurrence of low flow pulses and average decrease rate of flow have the greatest changes.