- 期刊
南化水庫及甲仙攔河堰考量河道放流量與供水之最佳營運策略
The Optimal Operating Policy of Nanhua Reservoir-Chiahsien Weir System for Considering Instream Flow Release and Water Supply
摘要
本文旨在利用多標的優選模式尋求同時考量供水及河川水域環境的南化水庫及甲仙攔河堰最佳營運策略。由於水利設施的興建與營運會對河川水域環境造成負面的影響，本文將以具有自然變化範圍的流量，亦即以變化範圍法(Range of Variability Approach, RVA)中的32個水文改變指標(Indicator of Hydrologic Alteration, IHA)來量化評估河川水流特性受水利設施蓄引水的影響，本文另將32個水文改變指標的水文改變度(degree of hydrologic alteration)整合成單一的整體水文改變度(overall degree of hydrologic alteration)，以利優選模式的演算。在水利設施的營運效率方面則以缺水率來評估。由於河道放流量與引水運用對水利設施的營運而言是互相衝突的標的，因此本文以多標的妥協規劃(compromise programming)來尋求同時對河川水域環境影響最小且缺水率最少的水利設施最佳營運策略。本文先以南化水庫及甲仙攔河堰興建前的1959年至1995年之日流量紀錄為基礎訂定河川流量未受水利設施影響的評估標準，經由模擬模式演算相同流量紀錄在南化水庫與甲仙攔河堰不同河道放流量時之下游河川流量，據以評估河川水流受水利設施的影響及相對之缺水率。本文所探討的情況有南化水庫及甲仙攔河堰在定值河道放流量及隨豐枯季節變化河道放流量時之河川水域整體水文改變度及缺水率，並利用妥協規劃推求在這些情況之最佳營運策略。演算結果證實本文所建議之方法不僅可以有效量化水利設施營運對河川水域環境的影響及用水的效率，更可將之整合於多標的優選模式中以尋求最佳營運策略。
並列摘要
In this paper, a multiobjective optimization model is presented to search for the optimal Nanhua reservoir-Chiahsien weir operation scheme aimed to simultaneously assure the water-supply stabilities and sustain the natural flow variations. The Range of variability Approach (RVA) and thirty-two hydrologic parameters, called Indicators of Hydrologic Alteration (IHA), are used to evaluate the hydrologic alteration of streamflows caused by reservoir-weir operation. The resulting hydrologic alterations of 32 IHAs are then combined into a single index such that it can be incorporated in the objective function of optimization model. Shortage ratio is used to evaluate the operation performance of water-supply system. Since water supply and instream flow release are conflicting, the multiobjective optimization model is needed to solve these conflicting objectives in water-supply system. The compromise programming algorithm is used in this study to derive the optimal reservoir-weir operation for simultaneously consideration of minimum impacts to riverine environment and minimum shortage ratio. The water-supply facilities considered in this study include the Nanhua reservoir and the Chiahsien weir. The daily flow records prior to dam and weir construction from 1959 to 1995 are used to establish RVA targets. A reservoir-weir operation model is established to derive the post-diversion flows for various operating schemes. In this study, various operating schemes, including constant inflow release and wet-dry season varying inflow release, are evaluated to determine associated impacts on shortage ratio and hydrologic alteration. The optimal instream flow releases are determined for various operating scheme using the compromise programming. The methodology proposed in this study could serve as a useful quantitative evaluation tool for the decision makers of the water-supply systems.