RAINDROP-INDUCED AND WIND-DRIVEN SOIL PARTICLE TRANSPORT

Abstract

A wind tunnel study under wind-driven rains was conducted to determine the combined effect of rain and wind on the rainsplash transport process. The rains driven by horizontal wind velocities of 6, 10 and 12 m s-1 were applied to three agricultural soils packed into a 20x55-cm soil pan placed at both windward and leeward slopes of 4.0°, 8.5° and 11.3°. Transport rates were measured by trapping the splashed particles at set distances in the upslope and downslope directions, respectively, for windward and leeward slopes. Rainsplash transport under wind-driven rains was adequately described (R2=0.93) by relating the transport rate to the 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.