Evaluation of the Relationship between the Nao and Rainfall Erosivity in Ne Spain during the Period 1955-2006

Rainfall erosivity is the ability of precipitation to erode soil. Microerosion processes due to the impact of raindrops on the soil – rainsplash – represent an important mechanism of detachment of soil particles, which might be removed thereafter by surface runoff. The annual and interannual patterns of rainfall erosivity are controlled by the variability of rainfall intensity. This study analyses the interannual variability of daily rainfall erosivity due to precipitation in the NE of Spain during the period 1955–2006, and its connection with the North Atlantic Oscillation (NAO). It was found that the erosive power of rainfall is stronger during the negative phase of NAO and weaker during positive NAO conditions, as are the rainfall amounts. Daily rainfall erosivity series were adjusted to a Generalized Pareto probability distribution for positive and negative NAO phases for assessing the effect of NAO on extreme events. Results showed higher values expected for a given return period in most of the area under negative NAO conditions. These findings would be useful in the implementation of soil conservation strategies.