Assessment of infiltration and erosion rates in Mediterranean reservoirs’ catchments through rainfall simulation

The land use and vegetation type of a reservoir's catchment substantially affect the hydrological processes of soil infiltration and runoff. They also act as drivers or constraints for erosive processes. All the previous processes influence the amount of water and sediment that reach the reservoir and affect its functioning. This study is mainly aimed to improve the knowledge of these processes in southeastern Spain by means of experimental rainfall simulation and multivariate statistical analysis. The results show that the mean infiltration rate is 1.06 times higher in forests than in shrublands and 1.07 times higher than in olive crops (280.52, 265.02, and 262.08 mm/h, respectively), with mean surface runoff consequently 1.57 times lower in forests than in shrublands and 2.41 times lower than in olive crops (20.81, 32.58, and 50.24 mm/h). Likewise, the sediment concentration in the runs is 5.48 times higher in olive groves (518.43 g/L) than in forests (94.61 g/L) and 2.94 times higher than in shrublands (176.48 g/L). Soil properties and parent material might have a more important effect on the studied variables than the different vegetation types. Furthermore, root systems and the use of tillage on crops could favor infiltration, which would tend to equalize the values of the variables analyzed; but this needs to be demonstrated in future research. The results obtained are of interest for vegetation cover and soils management in reservoirs’ catchments in Mediterranean areas. Furthermore, the current research provides an opportunity to study more specifically the origin of the sediment that reaches the reservoirs, beyond sheet and rill erosion.