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

Reservoirs serve as important facilities, providing a stable source of public water in Taiwan. As construction of new reservoirs becomes more difficult, it is essential to ensure sustainable functionality of reservoirs in the future. To this end, this study proposes a system for reservoir sustainability evaluation. The evaluation system consists of social justice, environmental protection, and economic development containing 12 indicators which are grouped into six categories: flood control, sediment management, water resources allocation, river ecology, water quality, and benefit and fairness. Moreover, evaluation system operational procedures to supplement planning and decision-making processes are proposed, and applied in a case study of the Shiwen reservoir planning in Taiwan. The planned reservoir in this case study is rated as “Good”, nearly “Excellent”, in sustainability as evaluated with the Sustainability Confidence Index (SCI). Additionally, Analytic Network Process (ANP) results indicate that the flood control capacity and sediment management are the first and second most important indicators for the reservoir. If desilting operations had been conducted, the SCI values would have increased from 3.3 to 3.7, warranting an “Excellent” rating for the reservoir. The case study demonstrates that decision-makers can apply the proposed system when managing reservoir evaluations.