Optimal Reoperation of Multi-Reservoirs for Integrated Watershed Management with Multiple Benefits

Abstract

Constructing reservoirs can make more efficient use of water resources for human society. However, the negative impacts of these projects on the environment are often ignored. Optimal reoperation of reservoirs, which considers not only in socio-economic values but also environmental benefits, is increasingly important. A model of optimal reoperation of multi-reservoirs for integrated watershed management with multiple benefits was proposed to alleviate the conflict between water use and environmental deterioration. The social, economic, water quality and ecological benefits were respectively taken into account as the scheduling objectives and quantified according to economic models. River minimum ecological flows and reservoir water levels based on flood control were taken as key constraint conditions. Feasible search discrete differential dynamic programming (FS-DDDP) was used to run the model. The proposed model was used in the upstream of the Nanpan River, to quantitatively evaluate the difference between optimal reoperation and routine operation. The results indicated that the reoperation could significantly increase the water quality benefit and have a minor effect on the benefits of power generation and irrigation under different hydrological years. The model can be readily adapted to other multi-reservoir systems for water resources management.

Development of an Evaluation System for Sustaining Reservoir Functions—A Case Study of Shiwen Reservoir in Taiwan

“…As recommended by recent studies in relevant fields [2,3,11,12,18,29,30,38,39,[41][42][43], the proposed indicators were established to evaluate environmental, water resource-related, and ecological sustainability in Taiwan, with the exception of fairness which is represented by the benefit index and Gini Coefficient. Therefore, in contrast with recent studies that have evaluated multi-purpose reservoirs, the proposed evaluation system takes the benefit index and Gini coefficient into account to ensure future water supply and reservoir sustainability.…”

“…A multi-objective reservoir evaluation, however, could be used to solve environmental and ecological problems while ensuring the sustainable functions of reservoirs [11,12,18,41]. The main focus of this study is to incorporate sustainability concepts when making planning considerations and during operations of multi-purpose reservoirs with the aim of improving reservoir sustainability for reservoirs in Taiwan.…”

“…Lian et al [30] applied SI for optimal Danjiangkou Reservoir operations in China. For domestic water use purposes, reservoir water quality is the most important part of sustaining water supply functionality, and is the topic of many studies producing various related indicators such as the water quality index (WQI) for reservoir operations and evaluations [12,33,34]. Moreover, water quality is one popular ecological indicator in sustainable development [35].…”

“…Chu et al [58] studied the impact on overall reservoir performance according to changes in the characteristics of local ecology, water quality, hydrology, and habitat environment. Recent attempts to solve the abovementioned environmental problems [12] and maintain reservoir functionality (i.e., power generation, flood control, habitat protection, water allocation, water quality, and sediment control) include using multi-objective reservoir operation modeling where water utilization and flood control targets are constrained by ecological flow or water quality.…”

“…Flood potential is a significant parameter when considering the tradeoff between flood control and conservation for sustaining reservoir functions in integrated water resources development [3]. Concerning water resources management, as sediment accumulation and potential flood problems not only decrease a reservoir's demand but also influence riverine ecosystems [1,[7][8][9][10]12] (e.g., fish habitats and downstream water quality), an effective evaluation system for sustaining multi-objective reservoir functions is essential to integrate water resources development and management. Accordingly, there are many factors which influence the functions of a reservoir, such as flood, sedimentation, water quality, and surrounding habitats [4,11,13,14].…”