RAIN DROP SIZE DISTRIBUTION AND SOIL EROSION

Soil erosion is caused, at least in part, by the impact of kinetic energy on the soil during rainfall. Therefore, a better knowledge of rain parameters (rainfall intensity, R, and drop size distribution, DSD) is useful. To assess the influence of rain on the amount of soil loss, an experimental site was set up in the Chianti hills (northern Tuscany, central Italy). The rainfall rate was measured by tipping-bucket rain-gauges and the drop size distribution by the classical Joss-Waldvogel (JW) disdrometer. A co-located system of gauges provided soil loss and runoff measurements. Some rainfall events occurring between September 2006 and June 2007 were studied, revealing relationships between R and DSD with the amount of eroded soil. The estimate of the hydrometeor impacting kinetic energy was based on DSD and R, and the results were discussed. The reliability of a widely used rainfall erosion index was also assessed and the impact of kinetic energy, computed by the measured DSD, considered