都市化與氣候變異對都會地區淹水之衝擊評估－以台中都會區為例

Abstract

近年來，隨著氣候之改變以及都市土地利用之變化，淹水災害之影響變得日益嚴重。都會區是一個複雜且敏感之系統，其降雨逕流過程往往受到人為構造物之影響，而形成複雜之水理流程，本研究將針對區域排水、雨水下水道系統以及地表逕流之交替互動情形，分別以分離演算法以及整合演算法，進行一維區排渠道變量流模式、都會區雨水下水道模式以及二維地表漫地流淹水模式之銜接，建構一套適合都會區之地表淹水模擬模式，以反映實際降雨逕流與淹水情形。本研究擬以臺中都會區為研究對象，研析都會地區受到氣候改變以及都市化相關淹水災害的衝擊影響。 此外，本研究藉由2008年卡玫基颱風淹水事件，進行上述兩銜接模式之檢定驗證，透過實測淹水範圍比對後，淹水趨勢大致皆吻合。同時，本研究將整合演算法以及分離演算法進行淹水潛勢圖之比較，結果指出整合演算法能更實際反應雨水下水道之迅速排水功能，其原因在於整合演算法容許溢流水體再次回流至雨水下水道進行排水。 最後，本研究採用整合演算法為基礎演算模式，以氣候改變以及土地利用改變作為主要探討因子進行境況設定並模擬，在境況設定中之都市土地利用因子設定，是以內政部地政司於1997年以及2007年兩次國土利用現況調查數化資料進行區分。另外，在氣候變化則分為1980年至1999年之氣候變異比較期，以及1980年至2009年之氣候變異現況，透過上述區分交叉配對四種情境。在各情境之模擬結果比較後顯示，土地利用變化所帶來之淹水範圍增加幅度大於氣候變異之影響，並隨著土地利用改變幅度愈大，其對淹水災害之衝擊就愈廣泛。

Recently, flood hazard has become progressively serious due to climate variations and urbanizations. The metropolitan area is a complex and sensitive system. The rainfall runoff process is primarily affected by the anthropogenic factors. The main objective of this research is to evaluate the impact of climate variations and urbanizations on flood hazards in Taichung metropolis. Two kinds of flood-inundation simulation modules, i.e. the separation algorithm and integration algorithm, linking the 1-D river routing model, the storm water management model and the 2-D inundation routing model, to study the interactions of regional drainage, surcharged manholes and surface runoff. In addition, in order to validate the accuracy of the separation algorithm and integration algorithm, the Typhoon Kalmaegi event in 2008 is applied to verify the above two algorithms. In general, the simulated results have good agreement with the measured data. Based on the simulated results, the present research has revealed that the integration algorithm is more practical to simulate the rapid storm sewer drainage function than the separation one. The integration algorithm is allowed overland flow to return into storm sewer drainage system once again. Finally, this research utilizes the integration algorithm as the computational model, considering the environmental factors of climate variations and urbanizations, to simulate the study case. In different urbanization setting, the study case is based on two kinds of landuse data which was supplied by Dept. of Land Administration in 1997 and 2007, respectively. In climate variations setting, the study case takes two periods (one is from 1980 to 1999 and the other is from 1980 to 2009) into account. Thus, the study case has four simulated scenarios. Based on a series of simulations, the results show that the urbanization causes more significant effect on inundation areas than climate variations. With the better urbanization, the flooding hazards will result in more damages in the metropolis.