Soil erosion and hydrology of the western Mediterranean badlands throughout rainfall simulation experiments: A review

Rainfall simulation experiments are widely used in geomorphological research in badland areas. This technique contributed significantly to our understanding of badland geomorphology in the Mediterranean belt. Due to the different types of simulated rainfall applied and the variable size of the plots a review of the State-of-the-Art is necessary. This study confirmed that rainfall simulations are well suited to (i) analyse runoff-infiltration processes and sediment detachment within badlands, and (ii) to establish the factors determining the hydrological and erosion response at interrill scale in badland areas.The hydrological response of badlands is characterized by rapid responses, low to moderate infiltration rates (ranging from close to 0 to 55 mm h− 1) and high runoff coefficients (i.e. > 60%). Positive relationships are observed between antecedent soil moisture content and rainfall intensity on the one hand, and runoff coefficients on the other. Sediment concentration and soil detachment rates are among the highest measured on the Mediterranean region (i.e. up to 84.8 g l− 1 and 4722.4 g m− 2 h− 1). Results show that rainfall intensity, runoff coefficient, and slope angle have a positive influence on sediment concentration and sediment detachment; in the case of rock fragment cover, its influence is variable according to the soil cover percentage.Rainfall simulations increase our understanding of the temporal and spatial variability of the soil erosion processes. However, rainfall simulation provides mostly qualitative rather than quantitative information because of the small plot size and the simulated rainfall characteristics due to facility for repeating experiments and recording a high quantity of data in short time. However, this method allows the comparison amongst different environments and soil conditions as the rainfall properties can be reproduced.

► Rainfall simulations increase our understanding of soil erosion processes in badlands.
► Runoff response is rapid, infiltration low to moderate and runoff coefficients high.
► Soil erosion are among the highest measured on the Mediterranean region.
► Rainfall intensity, runoff coefficient and slope angle affect positively to erosion.