Tactical sediment yield control to mitigating terrestrial and/or aquatic environmental impacts of forest road construction

Many studies have been identified forest roads as major non-point source im pact contributors of sediment resulting from forest activities in mountain environment. Thus, sediment deposits on slopes below roads make an importan t environmental issue of management approaches to riparian zones because of the numerous ecological linkages between terrestrial and aquatic ecosystem s. This paper demonstrates a PC-based imagery data processing system using digital orthophoto through the application to estimate the granitic sedimen t deposits eroded from roads constructed on watersheds in the mountains of Shiga Prefecture. The results showed the same time trends in sediment yield as earlier studies that documented large areas of sediment deposits during the earlier years after road construction followed by a rapid reduction in deposits in subsequent years. Also, a relationship was developed to descri be the area percent of the sediment accumulated on the slope in relation to the travel distance.