Survey on the Slope Protection Method for Sloped Farmland Aimed at Conservation of Regional Unique Landscape

Abstract

Japan's National land has many steep mountains and few flat lands. We performed slant ground use for a long time to secure farmland, in Japan. In slope protection methods of the sloping farmland, there are fundamental two types of “slope tamping” and “stone wall”. The slope protection methods of the sloping farmland are one of the elements characterizing a scene including sloping farmland as a thing peculiar to area. In this paper, we analyzed the type of the slope protection method of sloping farmland in the point of “one hundred selection of Japanese sloping farmlands” and the representative sloping farmland in Japan using a subsurface geological map drawn on a scale of 1 to 200000. The geology in each point of target area was classified into three main groups as volcanic rock, sedimentary rock and metamorphic rock. Three main groups were further classified by rock types or geological timescale. We formed clear that rock types or geological timescale of the subsurface geology in the point was related to the choice of the slope protection method of sloping farmland. We conducted a field survey based on this classification. As a result, in region where two or more subsurface geologies are adjacent, the rock of the subsurface geology next to each other in domains from the subsurface geological feature border to around 200m is used as materials of the protection method of sloping farmland.