都市雨水下水道人孔水位不確定性分析

Uncertainty Analysis of Manhole Water Stage of Urban Storm Drainage System

林旭信(Shiu-Shin Lin) ； 呂學建(Hseuh-Chien Lu) ； 李軒昂(Xuan-Ang Li)

《先進工程學刊》 10卷2期 (2015/04) Pp. 87-98

摘要

本研究提出一結合頻率分析，設計雨型，抽樣理論之雨水下水道人孔水位不確定性分析方法，以抽樣理論結合頻率分析、設計雨型模擬降雨事件之降雨量。利用拉丁超立方（LHS）抽樣，進行抽樣100次，評估暴雨經理模式中降雨逕流模組與幹線輸水模組之水文、地文參數之不確定性對於人孔水位影響。另使用拔靴法（Bootstrap）隨機抽樣產生300組Bootstrap樣本，搭配對數常態分佈，平均法、位序法設計雨型推估出25年、100年重現期之逐時雨量，並以此結果來模擬降雨事件之降雨量。研究中以新北市新莊區中港大排為研究案例，蒐集鄰近台北氣象站1951~2011年共61筆歷史雨量推估重現期雨量與其逐時雨量。以LHS進行100次SWMM水文、地文參數之抽樣，探討中港大排在情境一僅考慮SWMM模式參數具不確定時，情境二僅考慮降雨量資料具不確定時，情境三同時考慮降雨量資料及SWMM參數皆具不確定時，不同重現期下，人孔水位之不確定性分析。經分析結果顯示，S75人孔（位於貴子坑溪上游段）在情境三中，水位不確定性較低，C66、C70人孔（位於中港大排中、上游段）在25年、100年重現期，情境一與情境二中，水位不確定性較高。

關鍵字

頻率分析 ； 設計雨型 ； 不確定性分析 ； 拔靴法

並列摘要

This research combines frequency analysis, design storm, and sampling theory to evaluate the uncertainty of the manhole water level in drainage system. The rainfall is estimated by combining design storm, and frequency analysis. The effect of water level in manholes with uncertainty both from hydrological and geographical parameters of SWMM-RUNOFF and SWMM-EXTRAN module is estimated by Latin Hypercube Sampling (LHS), with 100 sampling size. The rainfall, of 25-year, and 100-year return period, events are generated by Huff method, ranking design storm method with lognormal distribution and Bootstrap random sampling technique (300 Bootstrap samples). Jhong-Gang Drainage System in Xinzhuang district, New Taipei city is employed as a case study. The hourly rainfall data of Taipei weather station, the closest one to case study area, from 1951 to 2011 are collected first. The uncertainty of water level of manholes in case area is then estimated within three cases: 1. only uncertainty of parameters of SWMM is considered, 2. only uncertainty of historical rainfall is considered, and 3. both uncertainties of parameters of SWMM and historical rainfall are considered. The uncertainty for each case is assessed by running 100 times SWMM in which the parameters of SWMM model are generated by LHS. Based on the analyzed results, the uncertainty of water level of S75 manhole in case 3 is lower; of 25-year and 100-year return period, the uncertainty of water level of C66 and C70 manholes is higher in case 1 and case 2.

並列關鍵字

SWMM ； frequency analysis ； design storm ； uncertainty ； bootstrap