本研究探討臺灣各集水區之洪峰流量特性及推導建立適合臺灣及其北、中、南、東各區的不同重現期洪峰流量之廻歸方程式,供推估各區無流量資料或資料不足之集水區之不同頻率的洪峰流量之用,以利設計水利或水土保持構造物大小時參考之用。本研究選擇記錄年數最少十年且不受水庫影響之水文站的年最大瞬時洪峰流量作爲分析對象。首先探討各集水區最大記錄洪峰流量之大小及特性和集水區特性之關係,並依Creager方程式之型式建立最大記錄洪峰比流量和面積之關係。本研究應用常態分佈、對數常態分佈、對數皮爾遜第三類分佈及極端值第一類分佈等四種方法對各水文站之洪峰流量作頻率分析,經比較評估意,採用臺灣水利界常用之對數皮爾遜第三類分佈所分析的結果,推導建立適合臺灣及北、中、南、東四個地區之洪峰流量與不同重現期(T)及集水區面積(A)之廻歸關係方程式,這些方程式可供推估無流量記錄集水區的不同重現期洪峰流量之用。本研究並推導建立不同重現期洪峰流量對平均洪峰流量的比值與變異係數的關係式,這些關係式可供推算流量資料數不足之集水區的不同重現期洪峰流量之用。
This study focused on exploring characteristics of and developing equations for estimating peak flows from upstream watersheds in Taiwan. Annual maximum instantaneous peak flows of gauged watersheds with at least 10 years of records and without significant flow regulation by reservoirs are analysed. Peak flow characteristics are discussed in terms of magnitudes, variabilities, and their governing factors. The maximum recorded annual peak flows of gauged watersheds were evaluated and related to drainage areas in a form similar to the Creager's equation. Equations relating peak flows to return periods and drainage areas were developed individually for Taiwan and its four regions, North, South, Central and East, according to the division by the Water Resource Planning Commission. These equations can be used to estimate peak flows for ungaged watersheds in repective regions. Relationships between peak flows of various return periods and the variation coefficients of peak flows were also developed. These relationships can be used to predict peak flows of various return periods for watersheds with only short periods of data that are not sufficient for proper frequency analyses. Peak flow estimates made with equations developed in this study can be compared with those calculated from other methods so as to allow optimum selections of reasonable peak flow values for designing soil and water conservation structures.