探討大漢溪流域供水及發電之氣候變遷衝擊與調適

Abstract

近年來，在全球氣候變遷下，氣象異常、降雨時空分配不均，且開發新水源較困難的情形下，使得既有水庫的有限水源更顯珍貴。此外，水庫淤積造成有效蓄水量逐年降低，水庫操作供水難度提高，影響水庫之供水與發電功能，因此如何管理有限的水資源，增進水資源有效利用，達到水資源最佳化調配逐顯重要。而過去往往只針對單一水資源課題進行研究，但在人口壓力、都市化等因素下，日漸重視水、糧食、能源三者彼此間的依存關係，期望透過分析不同部門之間的關連性以及交織的節點，提出一個全面性且可操作的政策來解決所面臨的問題。因此本文以大漢溪流域所含涵蓋之桃園地區為研究區域，配合VENSIM建置水資源供水系統動力模式，模擬石門水庫之操作運轉，同時考量水-糧食-能源鏈結之相關性，探討桃園地區在未來氣候變遷下對水資源供需情況及發電量之衝擊，分析不同的調適政策下之缺水風險，並討論對糧食及能源可能造成的影響。 水庫供水系統模擬結果顯示，現階段尚可滿足需求水量，但隨著目標年需水量逐年增加，以及氣候變遷情況下，缺水指標顯示缺水風險有上升的趨勢，增加新水源亦或增強多元化水源供給仍是未來不可忽視的問題；而水力發電在氣候變遷的情境下有減少的趨勢，由於水力發電主要為電力系統尖峰負載之調整，若未來水力發電量減少，而尖峰負載之缺口無其他方式即時補足，將可能導致整個電力系統的不穩定。

In recent years, the global climate change, uneven distribution of rainfall and the obstacle of developing new water resources, existing reservoir water is becoming more precious than ever. In addition, the reservoir sedimentation has decreased the effective storage and increased the difficulty of reservoir operation, affecting the reservoir’s function, of water supply and hydropower generation. Therefore, managing the limited water resources and enhancing the efficiency water resources utilization for optimal allocation becomes significantly important. In the past, studies usually focused on single water resources issue. However, under the population pressure and urbanization, the issue of Water-Food-Energy Nexus was highly valued. It is expected that a comprehensive and executable policy will be delivered to solve the problems faced by analyzing the interlinkages across different departments. Since 2014, Taoyuan has become one of the six municipalities in Taiwan, and the satellite city of Taipei metropolitan area. Recently, the rapid population growth and industrial development make the water demand increase annually. Therefore, the TaHan River Basin in Taoyuan was selected as the study area to develop the system dynamic model of the water supply and the operation of Shihmen Reservoir. The future climate change impact on water supply and power generation were investigated, and the risk of water shortage for different adaptation strategies and potential effect on food and energy were analyzed. According to the system dynamic modelling results, the water supply can still meet the demand at current stage, but the indicator also shows a growing risk of water shortage under the condition of increasing of target annual water demand and climate change. Therefore, developing new water resources or enhancing multiple water supply are definitely unignorably in the future. Results also indicated the hydropower decrease in the context of climate change. Hydropower mainly serves as adjust of peak loads of the entire power system. If the hydropower generation decreases in the future and the gap of the peak load cannot be replaced by other solutions, it could cause the entire power system unstable.