沖縄やんばる森林における崩壊危険地の地形特性の評価法

抄録

This study presents a method to locate and to map unstable sites prone to erosion in Yambaru Forest Area (YFA) in the northernmost part of Okinawa Island. Topographical factors, forest harvesting activities and road construction on steep slopes are likely to have significant effect on terrain stability. The assessment was performed through the detailed analyses of a DTM (10m x 10m). SAGA GIS Software was used to derive erosion potential related indices such as, slope length-gradient factor (LS factor), topographical wetness index (TWI), stream power index (SPI) and wind effects (WE), respectively. These data were used to build a map describing geographical locations of potential hazardous sites. The approach used in this study highlights important topographical factors contributed to erosion and the map produced provides beneficial information on potentially unstable slopes as a basis guideline for effective forest management planning.