Trade-Offs in the Water-Energy-Ecosystem Nexus for Cascade Hydropower Systems: A Case Study of the Yalong River, China

Abstract

The hydropower system’s water-energy-ecosystem nexus (WEEN) has gained particular focus in the last years. The water-use trade-offs between hydropower and ecosystem maintenance are complex and variable for cascade hydropower systems, leading to challenges in water resources management and sustainable development of hydropower. To understand the trade-off in the WEEN of cascade hydropower systems and their changes, a WEEN model using the multi-objective optimization approach is developed in this study, including maximizing cascade power generation, minimizing reservoir water footprint, and minimizing amended annual proportional flow deviation. These optimization objectives characterize the nexus’s water, energy, and ecosystem sectors. And the Pareto non-inferiority solutions are obtained by the third edition of the Non-dominated Sorting Genetic Algorithm. Also, we novelly propose an evaluation index called the Multi-objective Trade-off Index (MTI), a quantitative method with clear physical meaning to explore the trade-offs as revealed between different objectives by the solutions. A case study of the Yalong River, China, has shown that: 1) the larger the incoming water is, the more beneficial to the power generation and ecological benefits of the hydropower system; and 2) the trade-off degrees of the water sector with respect to energy-ecosystem and energy sector with respect to water-ecosystem decreases when the hydrological condition changes from wet to dry, while the degree of ecosystem sector with respect to water-energy increases. In general, the proposed MTI that quantifies trade-offs in the WEEN of cascade hydropower systems is efficient and feasible. Meanwhile, the MTI is also generic and can be applied to other multi-objective optimization problems.

Research on hydro-photovoltaic complementary analysis of Yangfanggou hydropower station on Yalong River

“…The Yalong River ranks third in "China's Thirteen Largest Hydropower Base Plan", after the Jinsha River and the upper reaches of the Yangtze River (Wu et al, 2022). The Yalong River, located in the west of Sichuan Province and is the largest tributary of the Jinsha River.…”

“…At present, China's 13 major hydropower bases, including Jinsha River, Dadu River, Yalong River, Wujiang River, Hongshui River, Lancang River and Yellow River, are also under comprehensive development and construction. Among them, the Yalong River Hydropower Base ranks the third in the "China's Thirteen Largest Hydropower Base Plan", second only to the Jinsha River Hydropower Base and the Yangtze River Upstream Hydropower Base, and the potential hydropower resources of the whole basin are 30 million kilowatts (Wu et al, 2022).…”

A decision-making method for reservoir operation schemes based on deep learning and whale optimization algorithm

“…Reservoir operation scheme is to generate a set of feasible operation schemes based on the results of real-time hydrological forecast and on the premise of determining the operation objectives and constraints (Wu et al, 2022a). Decision-making for reservoir operation scheme is to select the advantages and disadvantages of several feasible operation schemes at the future time of the reservoir (Zhu et al, 2017a;Vassoney et al, 2021), so as to make the reservoir obtain the maximum benefit of flood control and benefit.…”