| 摘要: | 近年來由於人口持續成長及產業迅速發展，以致土地利用型態結構大幅變遷。都市環境中不僅缺少林木及綠地截流，更因都市化後建築物及道路交通等建設密度增加，使得地表人工鋪面面積增加，綠地沼澤地等自然地貌相對減少，致不透水率表面積增大。因此，每當豪雨來臨，土壤滲透率降低，地面逕流匯集，迅速流入河川，導致洪水氾濫。台灣北部五堵、汐止地區，每逢夏、秋颱風期間所帶來之降雨，均造成當地嚴重的水患問題。除了基隆河整治工程缺失之外，汐止地區水患之成因與集水區開發之關聯性備受爭議，因此本研究乃利用遙感技術，分析汐止地區1986及2001年兩個時期之衛星影像，以取得土地利用型態變遷情形，應用地理資訊系統轉繪為空間變化資料，並運用農業非點源污染模式(Agricultural Non-Point Source Pollution, AGNPS)，探討土地利用型態對地表逕流之影響。分析結果顯示，汐止地區都市化土地有增加趨勢，而開發強度為影響地表逕流之關鍵因素。當開發強度小於網格空間1/5時，推估結果顯示汐止地區兩個時期之地表逕流量分布情形相同；當網格空間內有開發行為即視該區塊內土地利用變化顯著時，分析結果顯示，2001年之地表逕流量較1986年有明顯增加之趨勢。AGNPS模式推估結果受網格內土地利用型態所影響，亦顯示開發強度是造成地表逕流量差異之主要原因。
The landuse in Taipei County has been significant changed in the past two decades due to the fast increasing of population and economic development. As the result of urbanization, large area of slope land has been developed to satisfy the residential communities and transportation system needs. The highly intensive urbanization results in the increasing impermeable surface area, reducing rainwater percolation, enhancing surface runoff, and inducing urban watershed drainage problems. In this study, two different periods of MSS SPOT satellite images, the year 1986 and 2001, are used to compare the variation of landuse patterns in Hsichih Area of Taipei County. Five landuse types, such as the forest, shrub land, grassland, construction area, and water body are classified to analyze the landuse changes between the years of 1986 and 2001. The analytical results of landuse images are built as the geographic information system database and a grid-base pollution assessing model, Agricultural Non-Point Source Pollution (AGNPS), is used to assess the spatial variation of surface runoff. In order to assess the effect of landuse changes to surface runoff, five parameters, such as slope, aspect, and CN value of each year are converted into GIS database and to apply them to assess the distribution of surface runoff by AGNPS. The analytical result indicates that the surface runoff increase in those cells which a noticeable landuse changed from forest/grassland to construction has been defined. However, when the construction density of cell changes smaller then 20%, the difference of surface runoff is hardly examined. Consequently, I conclude that the increase of construction area is the main factor affects the distribution of surface runoff in Hsichih Area but the intensity of development in each evaluated unit also plays an important role to affect the final result. |
