地理資訊系統應用於集水區水文特性分析

Abstract

本研究主要係以複迴歸方法配合地理資訊系統之技術求取集水區諸地文因 子，再推求集水區尖峰流量與流域地文因子之間關係式。地文因子關係著 河流由上游往下游至河口時動力現象，對於逕流發生及流量歷線分佈有極 大影響，但以往受限於人工求取地文資料的不便，今以地理資訊系統求取 集水區地文因子，證實其為一快速可行之工具。本研究求出台灣省中部地 區及南部地區各集水區地文因子，除依此以複迴歸方法推求集水區各頻率 年尖峰流量外，並由地文因子更可充份瞭解集水區內水文現象，以形狀而 言，南部地區集水區形狀以狹長居多；而中部地區集水區多略似方圓，並 由中部地區及南部地區複迴歸相關係數得知，即使集水區面積甚為廣大， 尖峰流量受地文因子影響仍是很明顯，相關係數亦反應出水文均一性問題 。

This study first uses geographical information systems technologies to calculate watershed phy- siographical factors ，and then uses multiple regression analysis to find the design runoff flowrate for different return periods﹒Usually， the physiographic factors basically respond dyn- amic characteristics of stream flow systems wit- hin watersheds﹒ In addition ， they also play important roles on deter-mining general shape of runoff hydrographs at watershed outlet﹒ Because the traditional method in calculating physiogra- phic factors are somewhat considered to be both time-consuming and costly ，the GIS-basd method is thus introduced herewith and has been proved to be able to estimate all that factors not only fast but accurately﹒Also，the regression result show that the watershed peak runoff rates are highly related with these physiographic factors﹒ On the other hand ，these factors also specify the general shape of watersheds in Central and Southern Taiwan，which could be quite useful in understanding watershed characteristics﹒Finally，the regression results of this study also imply the 〝 hydrologic homogeneity〞 of the wat- ersheds in Central and Southern Taiwan areas﹒