2006 Volume 12 Pages 293-298
Red-soil erosion and runoff have led to agricultural and environmental problems in Okinawa, and effective measures which can reduce sediment yield in the farmland are necessary. For the purpose, advanced sediment management technique is required. GIS for sediment management in watershed was constructed using land use, length, and slope data at each slope to detect the erodible regions in a watershed. Consequently, the multi-point observation was carried out at six points in a watershed. In these studies, a soil erosion and sediment runoff model was tested to verify their applicability in predicting sediment yield on farmland and sediment runoff at watershed. The results have revealed that the model is effective to estimate the sediment yield at farmlands affected by various agricultural management conditions. In the present application to the watershed, the authors carried out some case studies to choose proper combinations of sediment yield reduction measures. The calculation has shown that the sediment runoff can be reduced by 74% if the combination is adequately chosen.
