Estimation of landslides hazard zones using a GIS [Geographical Information System]
1991
Samarakoon, L. (Ehime Univ., Matsuyama (Japan). Coll. of Agriculture) | Ebisu, N. | Ogawa, S. | Ohtabara, Y.
This paper presents the result of estimating landslide areas in a part of the Yoshino-river basin using Geographical Information System (GIS). A system of programs was developed for handling multi-source data and accomplishing image analysis and statistical analysis. For the present research, two Landsat TM scenes; September 1986 and November 1986 were used. They were interpolated, georeferenced and overlaid with other geographical data that are available in Kokudo Suchi Data system in establishing a GIS of Yoshino-river basin. It was assumed that the high moisture index in two seasons, after a long spell of rain and after a considerable dry period, could be related to the excess ground water in the area as far as the land cover remains the same. The research was carried out in two steps. First, the unchanged forest stand in both of the dates, or the evergreen forest cover was separated from the rest of the area using difference of NDVI scenes of two dates. Then random sampling was done over the unchanged forest stands and data for bands 3, 4, and 5 were extracted. Factor analysis was done using band ratios' 4/3 and 4/5 of both dates to separate samples with relatively higher moisture index. Finally, samples which were estimated as representatives of high moisture areas were used as training samples to classify the study area using Maximum Likelihood technique. The classified map was compared with the landslides susceptibility map of the area, and found that the estimated high moisture areas were highly correlated with landslide proven areas
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