Abstract
The effects of sabo buffer greenbelts to control debris flow depend chiefly upon both the trunk diameter of the trees and the space between the trees. A large tree has great resistance against debris flow. Sabo buffer greenbelts with little space between trees well catch debris flow. However, both the trunk diameter and the space between the trees are incompatible with each other if sound growth of forest is expected. In order to resolve this problem, this paper proposes the use of log crosspieces attached to trees in sabo buffer greenbelts. According to the results of the calculations, the use of crosspieces in such a mode is capable of specific resistance against specific intensity of debris flow. For example, one crosspiece about 3.5m long and 36.0cm in diameter can resist debris flow running at about 5.0m/sec. The results of the calculations also prove that the effects of the use of crosspieces in sabo buffer greenbelts depend chiefly on both the collision intensity of debris to the trees in the greenbelts and the resistance of the roots of those trees.
