集水區地形因子自動萃取之研究－土石流危險溪流判釋之應用

An Automated Extraction Analysis for Watershed Topographic Factors - Application of Potential Debris Flow Identification

林昭遠(Chao-Yuan Lin)

《中華水土保持學報》 31卷1期 (2000/03) Pp. 81-91

https://doi.org/10.29417/JCSWC.200003_31(1).0008

摘要

溪岸崩塌及土石流防治爲治山防災重點工作之一，台灣地質脆弱、地震頻仍，陡峻山區之野溪容易發生土石崩落，加上山區坡地超限利用的結果，涵養水源之林地大量減少，由於野溪平常缺乏足夠水量將堆積在谷地之土石運走，易造成累積，俟豪雨一來，即釋出大量土石産生土石流。土石流災害的防治，其工程技術屬於較艱鉅、治理經費高，宜以避災取代防災之理念。土石流危險溪流及危險區之劃定，嚴禁開發利用爲治本之道。本研究於陳有蘭溪集水區內，以新中橫公路與各溪流的交點爲評估對象，利用數值地形模型，萃取各交點之地理座標、河川級序、交點坡度、主流長度、主流平均坡度、河序1的數量、河川蜿蜒度、集水面積、周長及其它可能影響土石流成因之地形資訊，再與賀伯風災後，衛星影像常態化差異植生指數（Normalized Difference Vegetation Index; NDVI）之變化做檢測。多變量統計分析結果顯示集水區地形資訊對交點發生土石流規模分類之準確度可達90％。

關鍵字

濱水區 ； 土石流 ； 數值地形模型 ； 多變量統計分析 ； 地理資訊系統

並列摘要

Disaster mitigation measure is one of the important works for landslide and debris flow controlled in the riparian strips. Mass movement occurs frequently at the gullies located at the steep mountain areas due to weak geology and earthquakes. In addition, improper land use decreases the area of forests, which play important role in regulating water. With the characteristic of easy debris accumulation, upstream gullies have highly probability to trigger debris flow at typhoon season. To take the concept of elusion instead of prevention is more practicable because of technology difficulty and high expenditure in debris flow countermeasure, and it is the right way to zone the danger stream with potential debris flow and inhibit any utilization at these areas. This study develops a debris module that could extract the information of sites, which located at the intersections of road and stream. The information of stream order, slope of the intersection, stream length, average stream slope, numbers of stream order I, stream sinuosity, watershed area, watershed perimeter and other topographic information of the sites were all derived automatically in the module. Multivariate analysis shows that 90% of original groups, clustering magnitude of debris flow estimated from the changes of Normalized Difference Vegetation Index nearby the watershed outlets, can be correctly classified using topographic information of the study areas.

並列關鍵字

riparian ； debris flow ； digital terrain model ； multivariate analysis ； geographic information systems