2006 Volume 50 Pages 1027-1032
In these years, red-soil erosion and runoff have led to agricultural and environmental problems in Okinawa, and models predicting sediment runoff rate are required for the purpose of assessment on and development projects and sustainable management of farmlands. The authors constructed a soil erosion and sediment runoff model for small agricultural watershed. The model is a process-based model which predicts erosion rate from overland flow on hillslopes, sediment runoff from concentrated flow in channels, and sediment depositionin settling basins. It represents temporal variation of sediment runoff and discharged sediment particle size. Some processes and parameters of the WEPP model, such as plant, soil, management, etc., were partially employed. In case of the field scale application, the results have revealed that the model is effective to estimate the erosion rate at farmlands affected by various agricultural management conditions. These models were expandedto the watershed scale; the calculated suspended sediment movements were reasonable compared with observedones.
