Multi-temporal Analysis of Land Cover Changes in Nagasaki City Associated with Natural Disasters Using Satellite Remote Sensing

Natural disasters are inevitable and it is almost impossible to fully prevent the damage that they cause. However, it is possible to reduce the potential risk by developing disaster early warning strategies and to help in rehabilitation and post disaster reduction. Remote sensing technology has proven its usefulness, not only for monitoring disastrous events, but also to provide accurate and timely information well before the occurrence of a disaster. The study of the temporal changes of spatial patterns is important to understand the underlying factors and the functional effects. This paper addresses a multi-temporal analysis of land cover changes from 1986 to 2000 in Nagasaki City. Nagasaki City was studied using Thematic Mapper (TM) data acquired by Landsat-5. Particular attention is given to the selection of an appropriate method for land cover classification. A common and reputable unsupervised classification method, the Iterative Self-Organizing Data Analysis Technique (ISODATA) is used. The overall results of the study area show that the amounts of forestland and agricultural land are decreasing and in contrast the amounts of urban land and barren land are increasing. This trend is especially clear in detailed analysis of typically developed areas such as Tagonoura, Koebaru and Kaminoshima