雨水下水道淤積對於都市淹水之影響評估

Abstract

雨水下水道是現代化都市基礎建設之一，其主要功能為即時排除地表逕流，使都市免於水患，因此如何使下水道功能正常運作，為健全都市排水之首要課題。而長久以來，雨水下水道之維護管理普遍不受重視，工地污泥流入管路、砂石業者違法排放洗砂廢水、民眾廢置雜物、各事業單位管線橫越交錯等各式各樣的人為或是自然因素，皆對下水道既有功能造成重大的衝擊。 本研究首先挑選水利署易淹水地區治理計畫中常用之SOBEK淹水模式，針對模式演算理論部份，瞭解其運算方法、流程架構、格網建構與功能特點；而應用案例方面選擇台北市玉成抽水站集水區，進行模式之檢定與驗證；最後再進一步分析在該雨水下水道不同區段與程度之淤積條件下，對於都市地區淹水範圍與深度之影響。

Sewer systems, which are one of the basic constructions of modern city, have main function of draining surface runoff for preventing the occurrence of inundation events. Therefore, maintaining the normal function of sewer systems working is the core issue of city’s drainage. However, proper maintenance of sewer system has been ignored for a long time. Both human activities and natural effects cause egregious impacts on sewer systems, such as flux of sludge, illegal emission of waste water for washing sand, arbitrarily placing miscellaneous articles, and pipes crossing irregularly. This study first chooses SOBEK model as the numerical tool, which is usually used in WRA’s projects of simulating and managing easy flooding areas, and the model’s numerical methods, flowcharts, grid generation, and other functions. Second, the calibration and verification of SOBEK model is executed for the watershed of Yu-Cheng Pump Station in Taipei. Finally, the inundation areas and depths of the study area are evaluated under the conditions of different deposition levels and reaches of the sewer system.