Journal of Natural Disaster Science
Journal of Natural Disaster Science Vol.20, No.1, 1998
Discrimination of Landslide Areas Using Satellite Imagery and the Spatial Features of Watersheds
(Received 14 July, 1998 and in revised form 11 December, 1998)
Abstract
Landslide areas in the Noto district, Japan were analyzed on the assumption that the basin stream-flow, including underground-water, has an important effect on the occurrence of landslides. A watershed was treated as the basic area unit used to analyze the characteristic properties of landslide areas. First, watersheds were delineated from digital elevation data, then the segmented watersheds were divided into two groups; Dangerous Watersheds (DW) and Non-dangerous Watersheds (NW), using maps of dangerous landslide areas produced by the Ministry of Construction and the Forest Agency, Japan based on a field survey. Whether the segmented watersheds are correctly classified in DW and NW groups in terms of the physical and topographic factors of watersheds next was tested. The area and mean slope of a watershed were chosen as the topographic factors related to the run-off of the stream-flow, and surface temperatures during the day and night were selected as the physical quantities considered to be influenced significantly by underground-water. The vegetation index was chosen as the factor related to land use in the landslide areas. The surface temperature and vegetation index were estimated from Landsat Thematic Mapper (TM) data. Lastly, a discriminant analysis using the selected physical factors was performed. Results show that 85% of the 73 segmented watersheds was correctly classified as DW or NW, as estimated from ground data.
Key words
landslide area, watershed, Landsat TM image, surface temperature at night, underground-water, discriminant analysis