A multi-millennial reconstruction of gully erosion in two contrasting Mediterranean catchments

Cereal and olive cultivation are thought to have played a major role in triggering soil erosion since humans have settled in the south of Spain and in increasing gully activity since the relatively recent intensification of olive cultivation. To test these hypotheses, we dated the sediments and reconstructed the soil erosion history of two gullied catchments, in Baena and Montefrio, both located in the South of Spain but with well differentiated land management histories. To date the sediments, we established a multi-proxy chronostratigraphy based on radiocarbon dating, optical stimulated luminescence and archaeology. In addition, we used the reconstructed land management history of the two catchments and aerial photographs. The reconstructed soil histories of the two catchments suggest a close link between agricultural land management practices and soil erosion in the last seven millennia. Notably, results indicate that soil erosion activity started earlier in Montefrio, corresponding to the first human settlements seven millennia ago. However, in the last two millennia erosion and gully activity in Baena have rapidly overtaken that of the Montefrio due to a more intense economic and agricultural activity of the former. In the last decades, erosion and gully activity in both catchments have been very high due to the intensification of the olive cultivation.