國民小學天然災害風險評估之研究－以土石流、洪水、地震為例

台灣地區天然災害發生次數日益頻繁，尤其是在集集大地震之後，土體鬆動脆弱，每逢豪大雨必導致災情，校園安全面臨嚴峻的考驗。於此，天然災害的風險評估，不能只侷限於單一災害之考量，應以多災害的角度進行探討。本研究藉由文獻歸納，各別整理土石流、洪水、地震等三種常見災害之影響因素，以災害潛勢危害度與學校可能災害損失當作考量。危害度考量災害潛勢規模，並納入災害發生之機率；災害損失則以損失經驗曲線或學生人數及平均每生分攤經費進行計算，從以上兩者之計算結果界定出各災害風險等級。最後以地理資訊系統中的套疊分析方式針對台灣地區所有的國民小學進行風險計算，將風險地圖繪製於地理資訊系統上。研究發現土石流風險最高的學校集中分布於南投縣，洪水風險最高的學校集中於高雄縣市、屏東縣與花蓮縣，地震風險最高的學校集中於台南縣、嘉義縣與花蓮縣。另外全台灣的國民小學之中，可能受三種災害影響的學校有1所，但其對應的災害風險皆屬於低危害等級；可能受兩種災害影響的學校則有359所，很可能造成這些學校師生與財產的極大威脅。本研究希望藉由提供學校環境之各種災害風險等級，能讓社會再次重視天然災害對校園安全的影響。

關鍵字

災害風險；土石流；洪水；地震；風險地圖

並列摘要

After the Chi-Chi Earthquake, the natural disasters such as debris flows and floods occur more frequently in Taiwan, and these disasters usually threaten the safe of elementary schools. Due to assessing and evaluating the risk of disasters by single disaster is insufficient and incomplete; this study combines the disasters of debris flows, floods, and earthquakes to get the score of the risk. The risk assessment is based on the occurrence of the potential hazard and the losses of the elementary schools. The degree of the disaster hazard is according to the potential scale and the frequency. The losses of the elementary schools calculate from three data which are the empirical depth-damage curve, the numbers of students and average expenditure of per student. Finally, the Geographic Information System is used to analyze and map the risk of all elementary schools in Taiwan. The results reveal that the elementary schools in Nantou have the higher grade of debris-flow risk. Besides, the counties which have higher degree of flood risk are Kaohsiung, Pingtung and Hualien, and have higher risk of earthquake are Tainan, Chiayi and Hualien. There is only one school may be struck by the three kinds of disasters at the same time, but its risk of the three disasters are low degree. There are 359 elementary schools may be struck by two disasters. Finally, we hope that the risk map can be applied to prevent disaster of elementary schools.