The effect of land use change on landslide risk in Thailand

摘要

A landslide disaster occurred at Ban KathunNua, Phipun and Ban KiriwongLanska, Nakhon SiThammarat province in Thailand on November 22, 1988, causing loss of life and property. Twenty years of the disaster, this landslide may have brought about changes in land use, which would in turn have an effect on the risk of landslides. The objective was to study the changes of land use at a high elevation and the relationship between the vegetation index and landslide. Six periods of satellite images before and after the disaster were used, including the images taken in 1990, 1993, 1994, 1996, 2002, and 2007. Data analysis was carried out in order to calculate the amount of vegetation cover by calculating the NDVI representing the land use. The landslide probability was calculated using a mathematical model proposed by Pantanahiran (1994). The GRID model was used. Four levels of landslide hazard were classified; namely, low, medium, high, and very high. The results showed that the landslide model was an effective model in this study. Minor change in land use in the area after the landslide disaster was found during a short period of time. After that gradual change in land use increased until 2007. A significant change in land use was found in the lower part of the watershed; however, minor change was found in the upper part of the watershed because the land was not used for agriculture. Finally, the land use change of the area affected the calculation of the level of landslide hazard in the area.