供水系統綜合可靠度分析-以石門水庫為例

Abstract

水庫為台灣主要的原水供水來源，原水經過淨水廠處理後經由配水管網將自來水提供至使用者。近年來石門水庫由於高強度降雨造成原水濁度升高導致淨水廠無法負荷處理而停水，而這樣的問題於過去相關研究顯示供水系統可靠度，多集中於原水段或配水段，僅考慮各段的水量是否足夠而未考慮水質問題。因此，單以水量探討供水可靠度或缺水率、脆弱度、恢復度等風險概念，可能過於樂觀估計的情況。 為了真正了解供水系統的可靠度，本研究提出一個供水系統原水段可靠度之分析流程，建立供水系統原水段水量與濁度的模擬模式。以歷年的供水整體評估模擬結果顯示，倘若考慮濁度之影響，將使得缺水指數、恢復度及脆弱度提高而可靠度降低。而未考慮濁度之影響時，將使得缺水指數、恢復度及脆弱度降低而可靠度提升。雖然颱洪高濁度對於長期整體供水系統可靠度影響程度不大，但颱洪影響期間內高脆弱度及低可靠度之問題，仍是不容忽視的。

Raw water sources in Taiwan mainly come from reservoirs. Water treatment plants are commissioned to purify raw water to become drinking water. Through water distribution network, purified water can be delivered to the water consumers. Recently, the high turbidity of raw water induced by intensive rainfalls overloads the water treatment plants and causes water supply temporarily disrupted in the Shihmen Reservoir water supply area. Previous studies generally focus on the quantity of water rather than its quality. As consequence, it leads to underestimate the risk of water shortage and overestimate the resiliency, and vulnerability. This study presents a water supply system reliability analysis methodology and develops its evaluation model that takes into account both quality and quantity of water. Historical flow records and data generated by the time series model are both used in the water supply system reliability evaluation model. Results show that the indices such as water shortage index, resiliency and vulnerability increase if raw water turbidity is considered. Conversely, the reliability of water supply system reduces. Though the effect of higher turbidity is not found significant on system reliability in long term, short term events such as typhoons that can cause high turbidity still cannot be ignored.