Identification of gully-development processes in semi-arid NE-Spain

Gully erosion is considered to be one of the most important soil erosion processes, but its contribution to soil loss is still discussed. Despite the efforts made to understand the occurrence and dynamics of gullies, there is still a lack of knowledge on the factors leading to gully formation and growth. Within this study, the results from monitoring of gully-growth with high-resolution aerial photography are combined with the characterisation of the gully catchments with mapping of soil surface types and morphology and rainfall simulations. The results show an extremely high variability of gully-growth dynamics, being it independent from the size of the contributing catchment and rainfall characteristics. The distribution of soil surface types and their infiltration and erosion characteristics are identified as determinant for gully-growth. Additionally, their position related to the active gully-headcut is identified as determinant for the observed gully development.