不同集水區之集流時間對逕流量影響之研究

本研究探討集水區在不同集流時間的降雨事件中，利用流量與逕流量的關係式分析逕流相關係數與河川流量之相互關係，且由於颱風降雨為大範圍面積可讓整個集水區均勻降雨，因此選取對集水區有影響之颱風降雨資料並配合地理資訊系統推算出集水區坡度與土地利用程度、漫地流流向圖來比較其集流時間、降雨強度與坡度間之關係，並由分段估算法與Rziha分析兩種方法之間的相關係數比較。彙整2003年至2007年間五個不同流域之流量及雨量站資料，在颱風侵襲期間的流量和雨量資料與該其間共13個颱風的相關資訊，並依此分析各集水區逕流相關係數與河川流量關係之相關研究。研究結果顯示，以分段估算法為依據的分析方法較佳。利用地理資訊系統分析不同坡度及土地利用情形對集水區之逕流相關係數的影響，研究結果顯示集流時間與坡度成反比。在發生颱風情況下，各集水區開發程度與逕流相關係數除了林邊溪與北港溪外都成正比關係，而在以分段估算法為依據的研究中，逕流相關係數較合適，且計算值也較大。

關鍵字

逕流係數；集流時間；地理資訊系統；集水區

並列摘要

This study is aimed to analyze the co-relationship between different time of the concentration and the runoff-coefficient C1. In the typhoon attacking period, though the area of watershed is large, the rainfall tends homogeneously distributed. Therefore the data of rainfall and river discharge during the typhoon period will be used to analyze the effects on time of concentration due to different watershed slopes, extent of land-use, and rainfall intensity. The comparison between Sub-estimate method and Rziha method to calculate the C1 are also conducted. In order to analysis the co-relationship between different time of the concentration and the runoff-coefficient C1, the data of river-discharge, rainfall and related data of 13 typhoon in five different watersheds during year of 2003 to 2007’s period are collected. The results show that Sub-estimate method is more suitable to estimate the C1. By using GIS, the effects on C1 for different watershed’s slopes and extent of land-use are analyzed. The results show that as the slope becomes larger, time of concentration becomes smaller. During the period of typhoon, the extent of land-use is proportional to C1 except Lin-Bian River and Bai-Gang River. And the value of C1 is larger when it calculated by Sub-estimate method.