颱風對臺灣水稻災損之關鍵因子分析及應變策略

Abstract

根據科技部「台灣氣候變遷推估資訊與調適知識平台計畫」所發布「IPCC氣候變遷第六次評估報告之科學重點摘錄與臺灣氣候變遷評析更新報告」，近年由於氣候變遷的緣故，使得颱風強度提升，對農作物的威脅也日益增加。水稻為臺灣最主要的糧食作物，其產量及產值皆遠大於其他農作物，經濟價值及地位相當重要，但其災損就有高達七成五的比例是由颱風所導致，故本研究蒐集2009年至2018年全臺稻作主要產區災損資料及颱風統計資料，建立水稻颱風損失模型，以颱風的主要氣象特徵、影響臺灣時間、縣市別及侵臺路徑作為迴歸分析之解釋變數，探討颱風對臺灣稻作災損之關鍵因子。 研究結果顯示，強風為颱風造成稻作災損最主要的致災因子，而若當水稻處於抽穗期時，承受風雨的能力較弱，除了強風外，颱風所挾帶之短時間強降雨亦會使水稻損率上升，另外，單日累積雨量如超過門檻值150毫米，水稻災損會較為嚴重。其他方面，颱風影響台灣時間的長短對水稻災損並未顯著的影響，在臺灣稻作主要產區中，颱風對嘉義縣及臺南市兩地之稻作破壞力較大，而由於稻作產區主要位於中南部，在路徑別上，以第五類及第九類路徑這兩類行經臺灣南部的颱風路徑較具威脅。 在分析颱風對臺灣稻作生產之致災因子後，本研究提出應變措施之建議，包含增加防災措施、調整水稻栽培時間、種植具抗性之水稻品種、強化農民防災意識等事前預防策略，以及水稻保險等事後補救策略。另外，本研究建議未來水稻保險若規劃朝氣象指數型保險的方向發展，可嘗試以颱風的風速及單日最大累積雨量作為設計判賠標準的依據。

According to the IPCC Sixth Assessment Report Excerpts from Science Highlights and Update Report on Climate Change Review and Analysis in Taiwan issued by The Taiwan Climate Change Projection Information and Adaptation Knowledge Platform, due to climate change the intensity of typhoons has increased in recent decades and the threat to crops has also increased. Rice is the most important food crop in Taiwan, and its production volumes and values are also far greater than other crops. However, about 75% of the disaster damage to rice crops is caused by typhoons, Therefore, this study collects disaster damage data and typhoon statistics in the main rice producing areas in Taiwan from 2009 to 2018, and establishes a typhoon loss model for rice. The explanatory variables of the regression analysis include the typhoon meteorological factors, the landing time of typhoon in Taiwan, counties, and the typhoon tracks. The results of the study show that strong winds are the main cause of damage to rice crops caused by typhoons. If rice is at the heading stage, its ability to withstand wind and rain is weak which will increase the loss ratio. In addition, if the accumulated rainfall in a single day exceeds the threshold value of 150 mm, the rice damage will be more serious. On the other hand, the length of typhoon impact duration has no significant impact on the damage to rice. Among the main rice producing areas in Taiwan, typhoon has caused greater damages to the rice crops in Chiayi and Tainan counties. Because rice production areas are mainly located in the central and southern parts of Taiwan, the fifth and ninth typhoon tracks passing through southern Taiwan are more threatening than others. After analyzing the disaster-causing factors of typhoons on rice production in Taiwan, relevant countermeasures were also put forward, including increasing disaster prevention measures, adjusting rice cultivation time, planting resistant rice varieties, strengthening farmers' awareness of disaster prevention, and post-event remedial strategies such as rice insurance. In addition, if the future typhoon crop insurance will be introduced in the form of index insurance, this study suggests that wind speed and daily cumulative rainfall in typhoon disasters can be used to design the triggers and exit points of the payout.