應用雨量和地文因子建置以頻率比為基礎於淹水災害之研究

臺灣面臨多樣的災害，包含洪水、地震、坡地災害等災害類別，其中以洪水災害為發生頻率較高的災害類別。根據統計臺灣每年平均會受到3~5個颱風的侵襲，伴隨鋒面、梅雨等不同的降雨型態，導致臺灣多處受到淹水災害的威脅。因此掌握淹水可能發生的區域，降低淹水的損失是現今重要的課題。本研究以高雄市美濃區為研究區域，主要透過不同的地文因子與雨量和淹水面積之間的關係進行淹水災害分析。首先，選用坡度、土壤、土地利用、距河川距離、高程、植生指數等6種地文因子，藉由不同地文因子的分級，進行雨量和淹水面積的關係式建立。最後透過建立的關係式推估淹水面積，再藉由頻率比的計算，繪製出高、中、低的淹水風險圖。由結果顯示，運用建構出的雨量和地文因子與淹水面積之間的關係式，所繪製出的淹水風險圖，其中高風險與極高風險的分布區域，對照歷史災害事件中實際的淹水範圍，都有良好的結果。後續若能透過雨量與地文因子配合頻率比所產製出各區域的淹水風險圖，將有利於防救災整備工作的參考。

關鍵字

地文因子；雨量；頻率比；淹水風險圖

並列摘要

Taiwan faces various disasters, including floods, earthquakes, slope disasters and other categorical events, among which floods are the most frequently occurring incident. According to statistics, Taiwan is often visited by 3 to 5 typhoons on average every year, accompanied by different rainfall patterns such as frontal rain and the rainy season in May, which threatens the livelihood of many places with floods in Taiwan. Therefore, it is important to identify all areas of possible flooding to reduce any losses to the events. In this study, the Meinong District of Kaohsiung City was the area of interest. The flooding disaster was analyzed mainly through different topographic factors and level of precipitation in relation to the area affected. First, the relationship between rainfall and flooded area was established by using six topographic factors, such as slope, soil composition, land use, distance from river, elevation and vegetation index. Finally, through the established relationship, the flooding area could be estimated, and then a map of high, medium and low risk of flooding could be drawn by calculating the frequency ratio. The results showed that the flood risk map drawn by using the relationship between level of precipitation, topographic factors and flooded area, in which the distribution areas of high risk and extremely high risk were compared with the actual flooding range in history of disasters, had good outcomes. If the flood risk map of each region could be drawn from calculated frequency ratio of rainfall and topographic factors, such document could prove beneficial as a reference of disaster prevention and preparation work.