台中市區數值地形解析度對淹水模擬結果之比較

Abstract

本文利用淹水模式模擬暴雨期間之淹水範圍及淹水深度，地面之高低起伏與坡度直接影響地表逕流之漥蓄及流向，而地表坡度之精度取決於地形高程及解析度，因此淹水模式模擬結果的精確性與使用之數值地形解析度有關。而在都會區之淹水模式通常會再考慮整體雨水下水道系統、明渠排水與地表漫地流之交互作用等影響，更能反應都會地區實際之排水現象。 隨著航測技術的提升，在數值地形資料(Digital Terrain Model, DTM)上能取得資料之解析度愈來愈精高，解析度越高係指用以模擬的數值格網越細，本研究利用荷蘭近年來所研發的SOBEK淹水模式並以台中都會區中西屯區及南屯區之較易淹水區為研究範圍，並蒐集了地表高程、排水系統、下水道系統及土地利用情形等相關資料，將資料作整理、檢驗以及建置於淹水模式上，再分別以80mx80m、40mx40m、20mx20m、10mx10m四組數值格網，進行淹水模擬，以分析數值地形解析度對數值淹水模擬結果之影響。

This study makes use of a numerical inundation model to simulate the surface inundated depth and range in study areas. Ground elevation and surface slope affect amounts of the depression storage and the direction of overland flows. The Digital Terrain Model (DTM) is used to represent the the variation of ground surface. The precision of the surface slope depends on the resolution of the DTM. So the resolution of the DTM is a important factor influencing the accuracy and reliability of flood inundation model. With the improvement of remote sensing technology, we can obtain higher resolution of the DTM in recent years. The SOBEK model developed by the WL|Delft Inc., the Netherlands, is selected for inundation simulation in this study. The inundation-related information, including the geographic and hydrological data, sewer systems and landuse at Situn District and Nantun District of Taichung City were collected for detailed analysis . After that , four resolutions of DTM , 80mx80m、40mx40m、20mx20m、10mx10m , were used to simulate the overland flow pattern and the inundation depth in the study area by using the SOBEK model. Finally, influence on the results of four DTMs was investigated.