Abstract
An infiltration trench with wood chips is more efficient method to prevent reddish soil runoff in an upland field. To put the measure to practical use, this study unvails two factors influencing the sediment reduction efficiency and estimates the USLE support practice factor P value. For the purpose of this study, field experiment was conducted under natural rainfall condition using six experimental slopes. The slope dimensions are 30 m long by 1 m wide. It was found that the efficiency increased as the trench volume was gained, and was higher in the slope with multiple trenches than with single one. It seems likely that the amount of unsaturated gap volume in the trench during rainfall event would be directly related to sediment removal. USLE P value of the infiltration trench was in the range of 0.1 to 0.3, and was smaller than that of conventional measures. In conclusion, the volume and the arrangement of the infiltration trench are factors affecting the sediment reduction efficiency, and USLE P value is estimated as the efficiency.
