Rain properties controlling soil splash detachment

Laboratory experiments have been conducted to study the effects of various rain properties on sand detachment resulting from raindrop impact. Splash cups were exposed to simulated rainfall intensities ranging between 10 and 140 mm h(-1). The detached sand was collected and weighed whereas rain intensity, equivalent drop diameter and fall velocity of raindrops were measured with an optical spectro-pluviometer (OSP). The properties of the simulated rain (i.e, median volume diameter and kinetic energy) were compared with those observed in natural conditions. Statistical analyses have been undertaken in order to evaluate which rain variable best predicts the mass of sand detached. Linear and non-linear correlations between the mass of detached sediment and the product of drop size (d) by drop velocity (v), i.e. (DVbeta)-V-alpha, with values of alpha varying between 1 and 6 and beta between 0 and 3, have been computed. The results indicate that the coefficient of determination (R-2) for alpha ranging between 3 and 5 and beta lower or equal to 2 are satisfying. Although kinetic energy ((DV2)-V-3) described splash detachment relatively well, the product of momentum by drop diameter (D-4 V) was slightly superior in describing splash detachment. Therefore, the momentum multiplied by the drop diameter is recommended as the best rain Variable to describe splash detachment. Copyright (C) 2000 John Wiley & Sons, Ltd.status: publishe