Rainfall erosivity: process, indices and frontiers of knowledge

This article reviews previous studies related with the ability of rainfall to erode soil. Precipitation is one of the main agents of soil erosion, which started to be quantified since the beginning of the 20th century. The quantification of soil erosion and related processes allowed the development of empirical models for soil erosion determination and, more specifically, for describing rainfall erosivity. This last is based on raindrop kinetic energy, a fundamental variable for estimating splash erosion. Empirical studies found a relationship between kinetic energy and rainfall at high resolution time scales, allowing the estimation of kinetic energy from mathematical formulae using rainfall intensity. These relationships are related with the atmospheric, climatic and geographical characteristics of every location. Finally, recent works incorporating instrumental developments allowing more direct and real rainfall energy measurements, are reviewed. Finally, a short summary about Spanish research on this topic is included.