FLO-2D應用於中壢都會區的淹水分析

Abstract

近年來，台灣地區發生數起極端強度降雨事件，降雨超過都會區排水系統的設計容量，導致市區淹水。在大台北地區，淡水河流域的堤防保護標準為200年頻率洪水，台北市政府能夠負擔抽水機、分洪道和雨水下水道等防洪預算，降低淹水風險。然而，其他都會區政府依據財政情況，設置防洪措施和土地管理，若發生超過防洪工程保護標準的暴雨事件，都會區部分區域開始積水和交通癱瘓。 進行都會區的淹水分析，需得知暴雨事件中各地最大淹水深度、排水系統的水文訊息，研究人員將資料輸入二維淹水模式進行模擬。研究區域選擇桃園縣中壢龍岡地區的新街溪排水分區，採用二維淹水模式FLO-2D進行暴雨事件的模擬。 藉由數值地形模型(Digital Terrain Model)和都市計畫數值地形圖等圖層套疊以及FLO-2D的組件，在正確位置建置研究區域的模型，如建築物、道路和渠道等。以2012年0611豪雨的水災紀錄檢定FLO-2D輸出結果，評估FLO-2D是否能作為排水系統整合的分析工具。 本文對於檢定事件執行兩回合模擬，第一回合模擬是測試輸入參數和研究區域的模型，依據水災紀錄檢定參數和修正模型。第二回合模擬是與淹水紀錄和等高程線比較，探討FLO-2D的模式限制。之後，應用FLO-2D進行研究區域的暴雨情境模擬，評估累積雨量和降雨強度對於都會區的影響。最後，根據本文的討論和作者的使用經驗，對於FLO-2D淹水模式提出一些評論。

In recent years, several extreme rainfalls happened in Taiwan. The rainfalls which exceeded the designed capacity of the drainage systems in metropolitan area resulted in some inundated areas. In the Greater Taipei Area, the protection level of Tamsui River embankment was 200-years frequency flood. Taipei City Government could afford the budget of pumping stations, floodways, and storm sewers etc. to reduce its flooded risks. However, the governments in other metropolitan area set up the measurements of flood control and managed their land use according to their finance. If storms whose rainfall exceeded the design capacity of flood prevention engineering happened, some urban areas would be inundated. For the analysis of inundation in metropolitan area, what needs to be known were the maximum inundated depth in everywhere, the hydrologic information of drainage systems, and the rainfall records of storms. Then, researchers entered the data into two-dimensional flow model to simulate flooding events. In this article, Xin Jie Creek drainage partition, Chungli Longgang, Taoyuan County was selected as the study area. This article used FLO-2D, two-dimensional flow model, to simulate flooding events. Overlaying the Digital Terrain Model (DTM) layer and the urban planning digital terrain layer to constructed properly FLO-2D model components such as buildings, roads, and channels etc. in the study area. By the flooded records of 0611 torrential rain in 2012, it verified the output data of the flooding simulation. It estimated that FLO-2D could be the analytical tool of drainage systems integration. It executed two rounds FLO-2D simulation. First round of FLO-2D simulation was for testing the input data and the model of the study area, and it verified hydraulic parameters and corrected model. Second round of FLO-2D simulation contrasted with flooded records and contours, and this article discussed FLO-2D mode restrictions. Then, it simulated storm scenario in the study area by FLO-2D to estimate the influence of accumulated rainfall and rainfall intensity. Finally, this article gave a few comments on FLO-2D according to the discussion in this article and the writer's experience.