Long-term and mid-term ecological operation of cascade hydropower plants considering ecological water demands in arid region

Abstract

As the rapid development of economy, hydropower, as a kind of cleaner energy, is bringing in huge economic benefits, leading to the appearance of a great many of hydropower plants. Decades after the hydropower plants operation, series of quite serious ecological problems were brought in due to the changes in the natural flow. To restore the river ecosystem, this paper is making efforts on seeking series of operation schemes to balance the socio-economic and ecology benefits. Therefore, a simulation (Model-I) and an optimization (Model-II) operation model are established to provide a feasibility and a reasonable scheme for the multi-objective long-term and mid-term hydropower plant operation. To resolve the complex model, large-system coordinated decomposition method and an idea that efficiently narrows down the search space are used. The Irtysh River basin in China is selected as the study area to apply the model and make a trade-off to balance the water supply for socio-economics and ecology. The results show that the average annual power generation of hydropower plant group in Model-I is 2.5% more than that in Model-Ⅱ, both more than that of practical operation. In Model-I the water supply in dry year is far less than the minimum need (50%), but the Model-II provided a reasonable solution that the water supply in dry year is close to the median need (80%). Besides, the water supply for ecology in Model-II is obviously increased compared with Model-I, and the ratio increases from 56% to 86%, at the same time, the ratios to socio-economics are from 92% to 98%. Specially, the ratio of agricultural irrigation increases from 84% to 94%. In a word, the scheme meets the water requirements for socio-economics and ecology under considering the hydropower plants benefits, providing a scientific theoretical basis for water resource management.