應用淹水模式評估都市區雨水下水道之效能

Abstract

由於國內經濟的迅速成長，人口急遽增加，使得近年來各地區都市化的現象日益顯著；因之，有關洪水災害的問題亦日趨重要，尤其當雨季來臨，特別是颱風帶來之豪雨及夏季午後之暴雨，若所挾帶之降雨強度超過現有水利設施之設計容量時，而會造成淹水水患。 本研究主要目的，為利用荷蘭近年研發的SOBEK模式進行台中都會區之淹水模擬，並以發生於民國九十年桃芝颱風和納莉颱風對台中都會區所造成的洪災進行檢定驗證，研究過程中並蒐集研究區域各項地文、水文資料，與歷史颱風事件所造成的淹水範圍等相關資料進行分析。模式中包含了一維渠流模式和二維漫地流模式兩部分：一維渠流模式可以模擬暴雨期間天然河川主、支流之水深與流量及雨水下水道流況與人孔溢流量；二維漫地流模式則可模擬暴雨期間地表漫地流流況與洪泛淹水情形。 完成檢定驗證後的模式首先應用於建立台中都會區的淹水潛勢圖，再用以評估台中都會區雨水下水道系統對於淹水的改善程度，並且以台北縣三重蘆洲的模擬結果作為雨水下水道效能的驗證。研究成果將可提供都市區進行淹水研究時，在缺乏雨水下水道相關資料情況下，作為淹水模擬研判之參考。

Because of the growth of economics and population, the phenomenon of urbanization in Taiwan becomes more significant. The storms caused by typhoons take place in summer or autumn seasons that existing hydraulic facilities often cannot meet the demand and urban inundation results.

The SOBEK model developed by the WL|Delft Inc, the Netherlands, is selected for simulation inundation potentials in this study . The model is calibrated and verificated based on the typhoons Toraji and Nari in 2001, respectively . The inundation-related information, including the geographic and hydrological data, historical flood area records, of the Taichung City and its surrounding drainage basins were collected for detailed analysis. The inundation model includes the one-dimensional channel flow model and the two-dimensional overland flow model . The former calculates the water depth and the discharge in natural streams and the surcharges and the discharge in sewer system while the storm takes place . The latter is used to simulate the overland flow pattern and the inundation depth in the study area . After the processes of calibration and verification the model is used to establish the inundation potential map in Taichun City , and then to evaluate the effect of sewer system distributions in the drainage areas of the Taichung City . Finally , the simulations of Sanchung City and Luchou City were used to verificate the results .