| Summary: | 碩士 === 國立臺灣海洋大學 === 河海工程學系 === 99 === Taiwan has concentrated rainfall during typhoons and summer rainstorms, which usually result in a large amount runoff peak promptly. More recently, impacts from global climate change and local urbanization induce more serious flood disaster in cities and cause tremendous losses. In considering the limitation of urban storm sewer system during storms, a flood warning system may be able to provide useful information in advance to reduce the loss of property in urban areas. Since hydrological records are usually unavailable in urban catchments, the XP-SWMM hydraulic model was adopted firstly to simulate the rainfall-runoff relationships in urban catchments. Based on the data generated from the XP-SWMM model, a time-varying sewer unit hydrograph (SUH) was then developed for runoff prediction during rainstorm to obtain a computationally efficient and numerically stable model.
The SUH developed in this study is a nonlinear and time-varying hydrological model which can consider temporal rainfall distribution and flow hydraulic characteristics in urban sewer network system. The SUH model has been applied to two different sizes of hypothetical sewer systems for a priori check, and rainfall data and street inundation record from a severe typhoon in Lotong Township of Taiwan were collected to demonstrate the capability of the proposed model for runoff simulation in urban catchments. Analysis results show that flow hydrographs simulated by using the proposed SUH model are similar with those generated from the XP-SWMM model. The relative difference of hydrograph peak discharge was lesser than 15% for most simulation cases and the difference for the time to peak discharge was almost negligible, which has proved the applicability of the SUH model for runoff simulation in urban catchments. Moreover, a flash flood guidance (FFG) concept combined with a grey rainfall prediction model were also include in this study to develop a complete urban flood warning system for Lotong Township to avoid possible disaster.
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