Natural and anthropogenic controls on soil erosion in the Internal Betic Cordillera (southeast Spain)

Soil erosion in southeast Spain is a complex process due to strong interactions between biophysical and human components. Significant progress has been achieved in the understanding of soil hydrological behavior, despite the fact that most investigations were focused on the experimental plot scale. Although experimental plots allow exploring the effect of multiple biophysical and anthropogenic factors, they provide limited insights in the combined effect of all factors acting together at the landscape scale. In this study, area-specific sediment yields (SSY) have been estimated based on the volume of sediment trapped behind 36 check dams in the southeast of Spain. Low SSY-values were reported (mean = 1.40 t ha−1 year−1: median = 0.61 t ha−1 year−1). SSY variability could be explained for 67% by catchment characteristics such as drainage area, soil characteristics, land cover, average catchment slope, and annual rainfall. The low SSY values are probably caused by the agricultural abandonment that occurred over the past decades and allowed the recovery of natural vegetation. Furthermore, our results suggest that the soils have eroded in the past to such an extent that nowadays not much sediment is detached by overland flow due to residual enrichment of clay and stones. Also, sediment is to a large extent trapped locally in the catchment, as indicated by the negative relationship between SSY and catchment area.

Research highlights
► Area-specific sediment yields have been estimated for 36 check dams (SE Spain).
► SSY are unexpectedly low (mean = 1.40 t ha− 1 year− 1: median = 0.61 t ha− 1 year− 1).
► This can be the result of the low bedrock erodibility and the shallow soil profiles.
► Sediment detachment is also reduced due to residual enrichment of clay and stones.
► Vegetation cover and agricultural activities control as well the SSY variability.