STUDY ON AFFORESTATION OF THE ZELKOVA OF MOUNTAIN STREAM AND RAVINE RIVERS WHICH PREVENT OUTFLOW OF DRIFTWOOD AS PURPOSE

Abstract

Recently, outflow of the driftwood which originates in bank erosion and slope failure occur frequently. At Miyagawa of Mie prefecture the flood of the highest flow in observation history occurred in October 2004. In this flood, the cedar forest which is afforested to the side bank flowed out with stream bank erosion, but, the zelkova tree which has grown in the side bank did not flow out withstanding the flood.

From this circumstance, as for this study, the judgment whether afforestation of the zelkova tree in boundary of the river in order to control the occurrence of the driftwood is effective, and, history of afforestation of the zelkova tree and propagation circumstance etc of the zelkova tree were investigated.