臺灣集水區洪水情勢分析及其與環境因子之關係

Correlations between Flood Magnitude and Basin Characteristics in Taiwan

何佩容(Pei-Rong Ho)

指導教授 ： 詹仕堅

國立彰化師範大學/文學院/地理學系/碩士(2020年)

摘要

洪水頻率分析方法為防災設施規劃與管理的重要依據，國內外近期相關研究皆指出極端降雨事件的變化，強降雨頻率增加、降雨時間與空間分布的改變，因此未來受到洪水災害威脅的機率增加。且流域內各集水區環境特性不同，使各集水區之洪水特性呈現明顯差異，故本研究目的旨在分析臺灣各集水區洪水規模大小與其空間分布之差異，並探討集水區環境因子對洪峰深度之影響。使用1986至2014年34個測站觀測之日流量資料進行洪水頻率分析，再以適宜性檢定挑選出各集水區最適合之機率分佈，結果以任意重現期最大洪峰深度分析洪水情勢。接著探討洪水情勢空間差異之原因，運用相關分析結合地理資訊系統分析多項集水區環境因子對洪峰深度之影響，其中環境因子度量12項降雨特徵參數與11項地文特徵參數。
　　結果得知，各重現期之集水區洪峰深度值差異極大，且空間呈現出分布不連續的現象，而在不同重現期洪水情勢空間分布型態亦不相同，可能為集水區環境空間變異性所致，且為集水區環境特徵參數組合後共同作用影響，參數間彼此亦存在相依特性。影響洪水情勢主要因子包括：豐水期降雨強度之中位數、百年重現期最大一日與二日雨量、集水區面積、排水密度、主流河道平均坡度、河川長度比、地面流長度，在雨量參數中須同時考量氣候降雨平均狀態與極端降雨的可能情況；地文參數中集水區面積仍具有規模效應，且剩下四個參數有三個皆與河道網路有關，以臺灣洪水而言，集水區之河道系統可能較坡面或形狀更為具影響力。透過上述分析結果，理解在臺灣可能相對重要的集水區環境影響因子，以做為未來結合區域洪水頻率應用之基礎。

關鍵字

洪水 ； 頻率分析 ； 環境因子 ； 地理資訊系統 ； 典型相關分析

並列摘要

Considering the critical role of flood frequency analysis to flood control planning and management, changes in extreme events such as more frequent heavy rainfalls and differences in temporal and spatial precipitation patterns which have posed in heightened threat of flood disasters, and the individual nature of watersheds. This study aimed to analyze flood magnitudes and their relating spatial distribution of Taiwan watersheds, and investigate connections between the depth of flood peaks and watershed environments. To achieve this, 34 discharge stations were selected as data base, four probability distributions were applied to conduct flood frequency analysis, and then correlation analyses were chosen to sort out connections between the depth of flood peaks and watershed precipitation and morphology variables. It pointed out the value of flood peak depths against flood return periods or watershed varied significantly in this study, nor does their spatial distributions. Also, there was obvious spatial discontinuity phenomenon of watershed flood peak depths. These could be the result of the highly spatial variability of the watershed environments. With the advance of Canonical Correlation Analysis, it suggested main factors relating to flood magnitudes are rainfall intensity during the wet season, maximum one-day and two-day rainfall in the 100-year return period, watershed scale, drainage density, average slope of the mainstream channel, river length ratio, and surface flow length. As for rainfall factors to flood peak depths, they are average rainfall intensity of wet seasons which stands for the average weather conditions, and the maximum one-day and two-day rainfall in the 100-year return period which describes the possibility of extreme rainfall . At last it also revealed there is certain scale effect on the size of the watershed. Among four morphometric parameters, three are related to the river network. This showed river network systems of the watershed may play more important roles than slope or shape factors.

並列關鍵字

Flood ； Frequency analysis ； Environmental factors ； Geographic information system ； Canonical correlation analysis

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