乾溪流域水文分析

Abstract

中文摘要

本報告以乾溪流域作為研究區域，乾溪排水路線彎曲，上游坡陡流急，河道兩岸多私有土地，因此主流草湖溪匯流點容易使外水頂托，洪水排除不易而造成洪水災害，因此如何有效地分析流量是水利系學生需思考的問題。本報告分析該集水區內之降雨特性、頻率分析、設計雨型以及洪峰流量推估，並至現場實地探勘流域附近的地理狀況。 操作流程先採用霧峰、國姓、土城三個雨量站為乾溪流域之雨量資料，針對出口、萊園溪排水匯入前、牛欄貢溪排水匯入前與光復排水匯入前等四個控制點作頻率分析，決定控制點最適配機率分佈下的最大一日頻率雨量，接著利用Horner公式以及高斯馬可夫法設計雨型計算各頻率年設計暴雨，最後利用三角形單位歷線和設計暴雨褶合積分，演算各控制點各頻率年的洪水流量歷線，再取其洪峰流量和合理化公式計算的洪峰流量進行比較。 本報告經計算結果分析，初步建議以合理化公式作為各控制點設計洪水量採用值，其原因在於合理化公式各重現期距之洪峰流量相對合理與較大，在後續設計排水設施上為最為保守。

Abstract In this report, we use the Qianxi Basin as the research area. The Qianxi drainage route is curved, the upstream slope is steep and the flow is rapid, and there are many private lands on both sides of the river. Therefore, the mainstream Caohuxi confluence point is easy to support the external water, and it is not easy to remove floods and cause flood disasters. Therefore, how to effectively analyze the flow is a question that the students of the department of water resources engineering and conservation need to think about. This report analyzes the rainfall characteristics, frequency analysis, design hyetograph and peak discharges estimation in the catchment area, and on-site exploration of the geographical conditions near the watershed. First ，the operation process uses the three rainfall stations of Wufeng, Guoxing, and Tucheng as the rainfall data of the Qianxi River Basin.Focusing on the export, before the drainage of Laiyuan River, before the drainage of Niulangong River and before the drainage of Guangfu, etc. Four control points are used for frequency analysis to determine the maximum daily frequency rainfall under the most suitable probability distribution of the control points, and then use Horner formula and Gauss-Markov method to design rain patterns to calculate the design storm for each frequency year, and finally use the triangular unit hyetograph and the design storm Convolution integral is used to calculate the total runoff hydrograph history of each frequency year at each control point, and then compare its peak discharge with the peak discharge calculated by the Rational formula. According to the analysis of calculation results in this report, it is initially suggested to use the Rational formula as the value of the design flood volume for each control point. The reason is that the peak flow of each return period of the Rational formula is relatively reasonable and large, and it is the most conservative in the subsequent design of drainage facilities.