Is rainfall erosivity increasing in the Mediterranean Iberian Peninsula

The risk of erosion and desertification is one of the main environmental concerns in the Mediterranean Iberian Peninsula. Changes in precipitation are expected in Mediterranean areas because of climate change, but predictions are not certain. For this reason, dense precipitation databases are required to explore observed changes in the amount, concentration and variability of precipitation, to gain a clearer understanding of the dynamics involved in the main climatological agent of erosion. For this study, we took the recently developed MOPREDAMES dataset, which includes 1113 complete and homogeneous monthly rainfall series from the Mediterranean fringe of the Iberian Peninsula (IP) covering the period 1951-2000. These were used to calculate and analyse trends in Total Annual Precipitation (Pt), the Precipitation Concentration Index (PCI) and Modified Fourier Index (MFI). Our results show that, although there were decreases in annual rainfall, increases in the concentration of precipitation also predominated in the Mediterranean Iberian Peninsula during the period 1951-2000. However, spatial variability of these trends is high, and changes in rainfall erosivity exhibit a complex spatial pattern. Thus, decreases in rainfall erosivity are detected under semiarid conditions (Central Ebro basin and South East IP), while increases mainly occur in dry and sub-humid areas. We present a detailed spatial description of the results and discuss their implication for the risk of erosion and desertification in different regions of the study area. Copyright © 2009 John Wiley & Sons, Ltd.