Submitted to: Catena
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2001
Publication Date: 3/1/2002
Citation: ERPUL, G., NORTON, L.D., GABRIELS, D. RAINDROP-INDUCED AND WIND-DRIVEN SOIL PARTICLE TRANSPORT. CATENA. 2002. 47(3):227-243. Interpretive Summary: In severe storms that cause erosion intense rain is usually accompanied by strong wind. Data on the extent of how wind changes the amount of erosion is lacking because of the difficulty in conducting such experiments. We used a wind tunnel/rainfall simulation facility to study the effect of wind velocity on soil loss in directions facing the wind and away from the wind. With three different agricultural soils we found that wind increased the erosion of rain of the same intensity on the slopes facing the rain and reduced the erosion on the slopes away from the wind. Once soil particles were detached and lifted into the wind they were transported considerable distances away by the wind, some greater than 20 feet (the maximum distance of the tunnel) with only 26 mile per hour wind. The practical impact of this research is that when slopes face the predominant wind direction, users should consider the use of windbreaks to reduce wind velocity to control soil loss by water. Soil conservations can utilize this information to make more cost effective erosion control plans. Farmers can help control erosion on their fields by using windbreaks to slow wind velocity near the ground surface.
Technical Abstract: A wind-tunnel study under wind-driven rains was conducted to determine the combined effect of rain and wind on the airsplash transport process. The rains driven by horizontal wind velocities of 6 m s**-1, 10 m s**-1 and 12 m s**-1 were applied to three agricultural soils packed into a 20 by 55 cm soil pan placed at both windward and leeward slopes of 4.0, 8.5 and 11.3 3degrees. Transport rates were measured by trapping air-splashed particles at set distances in upslope and downslope directions, respectively, for windward and leeward slopes. Airsplash transport under wind-driven rains was adequately described (R**2 = 0.93) by relating transport rate to rain impact pressure and wind shear velocity by log-linear regression technique. Average trajectory of a raindrop-induced and wind-driven particle was also adequately predicted by the momentum loss per unit time per unit length of travel (U* **2/g). The travel distance is found to be three times greater than the path of a typical saltating sand grain.