Evaluation of the Effect of Wind Velocity and Soil Moisture Condition on Soil Erosion in Andosol Agricultural Fields (Model Experiment)

Abstract

Soil erosion by the wind is an important phenomenon in drastic soil degradation. In Japan, andosol agricultural field is eroded by the wind and agricultural productivity is significantly affected. The aim of this study was to evaluate the effect of wind velocity and soil moisture condition on the soil erosion in andosol agricultural fields. Also, we determined the timing and amount of irrigation water needed to prevent soil erosion by the wind with respect to the wind and soil moisture conditions. A numerical model to simulate airflow in bare andosol field was developed using a continuity equation and Navier Stokes equations. Wind tunnel experiments which described a bare andosol field were performed to measure the degree of soil erosion for four levels of soil moisture condition and five wind velocities. Using the measured amount of soil transferred by wind, the erodibility parameter in Bagnold’s method that quantifies soil erosion was estimated inversely for four soil moisture values. The amounts of soil erosion calculated using this parameter were in good agreement with the measured amounts. These results indicate that the soil moisture and wind conditions under which soil erosion occurs can be determined and the amount of soil erosion can be predicted. Using these conditions and the erodibility parameter, the amount of irrigation needed for the prevention of soil erosion was quantified and the effect of irrigation on soil erosion was evaluated.