結合季長期天氣展望發展乾旱預警與支援決策系統

Integrating Seasonal Weather Outlook to Develop a Drought Early Warning and Supporting Decision-Making System

田育全(Yu-Chuan Tien)

指導教授 ： 童慶斌

國立臺灣大學/生物資源暨農學院/生物環境系統工程學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201700619

摘要

台灣的降雨時間分布不均，乾濕季分明，在乾季若降雨不如預期，時常會導致水庫蓄水量不足，進而促使政府宣布限水。近年來，在氣候變遷的影響下，極端氣候事件頻頻發生，豐枯水期的雨量差異更為懸殊，再加上工業區的發展與擴建，導致需水量上升與缺水情況惡化。若枯水期的水情不佳時，往往會造成顯著的經濟損失。由於興建水庫等水資源設施需要時間規劃與建造，無法短時間內對現況與未來的乾旱風險進行調適，而非結構性與相對較彈性的乾旱預警與風險管理是一個有效的調適手段。過去政府進行乾旱預警時，僅以歷史的低流量進行未來水庫蓄水量之推估，做為乾旱決策之依據，並沒有一個可以利用氣候預報推估未來水情的工具。本研究利用中央氣象局季長期天氣展望之預報資料，透過氣象合成模式(WGEN)、水文模式(GWLF)、水資源系統動力模式與乾旱決策模型，建立結合季長期天氣展望之乾旱預警與支援決策系統，並以此乾旱預警與支援決策系統做為調適手段，以因應乾旱的來臨提早做出決策，降低乾旱之風險。
本研究以新竹地區為例，參考科技部氣候變遷調適科技整合研究計畫（TaiCCAT）氣候調適六步驟，執行步驟一至步驟四，從界定問題與設定目標、評估與分析現況風險、評估與分析未來風險、界定與評估調適選項，再以乾旱預警與支援決策系統做為調適選項，評估此支援決策系統之效益。研究結果顯示在未來氣候變遷的影響下，新竹地區的供水承載力下降且公共需水量上升，導致有供水缺口，需執行調適選項以降低乾旱風險。而以2011與2015年的乾旱事件為例，乾旱預警與支援決策系統在完美預報的季長期天氣展望中，可以提早得知乾旱的發生，並提前進行農業停灌、限水等措施，降低乾旱可能帶來的風險。但若使用實際的季長期天氣展望，預報的不確定性會造成支援決策系統誤判水情，做出不適當的決策，反而使乾旱風險提高。

關鍵字

季長期天氣展望 ； 乾旱預警 ； 風險管理 ； 氣候變遷 ； 調適

並列摘要

In Taiwan, the temporal distribution of rainfall is uneven. If the rainfall is not as expected in dry season, government may announce rationing because of low storage of reservoir. Due to the influence of climate change, extreme climatic events happen more often and result in larger difference of rainfall between wet and dry seasons. In addition, the development of industrial areas led to increase water demand and worsen water shortage, and it would cause significantly economic loss. Compared to building a reservoir, which needs longer time to plan and to build, drought early warning system and risk management might be a better way to reduce the drought risk. In the past, the drought early warning system in Taiwan only use statistical low streamflow that happened in history to project the water storage of a reservoir, and use this information to make decision during drought. The government does not have a tool to consider climate forecast. In this study, the seasonal weather outlook produced by Taiwan Central Weather Bureau (CWB), the weather generator(WGEN), Generalized Watershed Loading Functions(GWLF), water supply system dynamic model and a drought decision model were intergrated to establish a drought early warning and supporting decision-making system. This system can suggest decisions to reduce the drought risk when drought is coming, and serves as a climate adaptation measure.
Hsinchu area is chosen as a case study in this research. This study follows the six-step adaptation procedure to evaluate the risk of climate change, which developed by the Taiwan integrated Research Program on Climate Change Adaptation Technology (TaiCCAT). The first four steps are used in this research, including problem identification and goal setting, current risk assessment, future risk assessment and adaptation options identification and assessment. The drought early warning and supporting decision-making system serves as an adaption measure. The results show that the water supply carrying capacity of Hsinchu area decreases and the public water demand increase, resulting in water supply deflicts and needed adaptation measures to reduce the risk of drought. The droughts in 2011 and 2015 were used to assess the new drought early warning and supporting decision-making system. With perfect projection of seasonal weather outlook, this system can predict the drought and make proper decision to decrease the risk of drought. However, the uncertainty of the seasonal weather outlook would make the system misjudge and the system would make inappropriate decisions, making the risk of the drought become higher.

並列關鍵字

Seasonal Weather Outlook ； Drought Early Warning ； Risk Management ； Climate Change ； Adaptation

參考文獻

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