A Simulation Study on Utility Design of Urban Rainfall Retention and Their Effectiveness
Date Issued
2015
Date
2015
Author(s)
Huang, Yue-Ying
Abstract
This thesis simulates and analyses the regulations and strategies about flood management, including “Regulation Amendment for Building Rainwater Harvesting, Reuse, and Detention, Design and Technical Specifications”, “Building Technology Rules, Design and Construction articles”,”Taipei Construction Site Rainwater Drainage Standard”,“Low Impact Development Design Handbook”, with drainage system data of Liu Cuo in Nantun Dist., Taichung Country. Therefore, we examine their effectiveness in reducing runoff and peak flow. The effective rainfall time series are processed by the curve number method of SCS. And thesis time series are the input of BKW model which can calculate and output runoff time series. Then combining with EXTRAN module in SWMM, we construct two layer drainage system, sewer system and street system, as well as importing the dates from BKW model. Two layers in SWMM are connected by weirs, which can simulate the phenomenon that the flow in sewer system overflow to streets or flow in the street system backflow to sewers. Then thesis evaluates the strategy and facilities with BKW+SWMM model and design hyetographs, which are built from Horner’s equation and SSGM with local variables. About simulating facilities, decreasing the curve number performs the change after applying Low Impact Development and establishing the storages and weir in SWMM present the region installing rainfall retention space(雨水貯集滯洪容積= rainwater storage and retention volume). From the simulation results, Low impact development is effective when the total rainfall volume are relative small. However, rainfall retention space can effect reduce the peak flow which the drainage system can’t bear. Additionally, there is a phenomena that if we set rainfall retention space and let them distribute evenly in space, there are specific ones be used which are located in lower elevation area or closed to the ends of sewer. According to the analysis of simulation results, this thesis proposes the flood management in urban area can be “reducing volume in upstream, retaining flood in midstream and preventing flood in downstream”.
Subjects
BKW
LID
Rainfall Retention Space
Type
thesis
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