Low-Impact Optimal Operation of a Cascade Sluice-Reservoir System for Water-Society-Ecology Trade-Offs

As an important measure used to balance the trade-offs of industrial, domestic, and ecological water use sectors, the low-impact optimal operation model of the cascade sluice-reservoir system (CSRS) has developed into an international concern. Limited by insufficient water storage and a deteriorating ecological environment, the actual operation ability (AOA) deviates from the originally planned ability and cannot function effectively as expected. However, the focus on the quantification of the AOA of the CSRS and its applications in water resources allocation have not received sufficient attention. This paper first constructed a multi-indicator evaluation system of the AOA consisting of water quantity, water quality, water ecology, engineering, and socioeconomic elements. Second, based on the quantified AOA, a multi-objective optimal operation model of the CSRS was proposed to lower water deficiency and pollutant loads and to reduce the negative impact on the social economy, water ecology and environment. The Shaying River basin (SRB), a human-altered basin with fierce water use competition, was selected as the study area. The results indicate that (1) the elements of water quality and water ecology are the main factors limiting the AOA. Moreover, the evaluation system is able to accurately demonstrate the evolution of the water management policies. (2) The low-impact optimal operation scheme has a stronger superiority with less water shortages in both city units and ecology, especially when the inflow is less and the benefits of agricultural, industrial and domestic water use are prioritized. The model contributes to the knowledge of water-society-ecology trade-offs.