Journal of the Japan Society of Erosion Control Engineering,
Vol.57,No.2,,2004
Study on predicting method for area with collapsing possibility
considering deforestation and reforestation
Chie KUROIWA, Shinya HIRAMATSU
Abstract
Improper forest management frequently causes serious damage to hill slopes and torrents. This study examined the influence of annual variation of deforested and reforested areas on slope failure in Miyakawa]dam basin, Mie prefecture and Nagasawa]dam basin, Kochi prefecture. The followings were observed in this study:1) Collapsed area is proportional to the non]forested area and inversely proportional to the reforested area. 2) Slope failure frequently occurred after 5]7 years of deforestation in both the basins. In reforested sites of Miyakawa]dam basin, slope failure declined after 20 years of reforestation. On the other hand, many slope failures occurred in non]forested sites even after 24 years of deforestation. In Nagasawa]dam basin, there occurred little slope failures after 10 years of deforestation. Using these findings, a slope failure prediction model considering precipitation and forest management conditions was developed, and the model was applied to Miyakawa]dam basin and Nagasawa]dam basin over a30years simulation period. The comparison of the measured and simulated collapsed area ratio showed that the model was adequate for predicting the slope failure areas of both the basins.
Key wordsFforest management, deforestation, reforestation, precipitation MODEL, slope failure, prediction model
Japan Society of Erosion Control Engineering
Sabo Kaikan, 2-7-5 Hirakawa-cho, Chiyoda-ku,
Phone +81-3-3222-0747 Fax +81-3-3230-6759
http://www.jsece.or.jp/
Mail jimu@jsece.or.jp