Dino Torri (1), Jean Poesen (2), Mauro Rossi (1), Sofie de De Geeter (2), Cati Cremer (2), 2019, Gully head modelling in Mediterranean badland areas, 8TH INTERNATIONAL SYMPOSIUM ON GULLY EROSION ISGE 2019, TOWNSVILLE (AUSTRALIA), 21/07/2019,
URL: http://www.cnr.it/prodotto/i/429739

The prediction of the location of gully heads in various environments is an important step towards predicting slope and catchment dynamics and to properly estimate soil erosion rates. So far, data collection and modelling of topographic thresholds for gully head prediction has mainly focused on forested areas, rangelands, pastures and cropland. However, such data for badlands are very scarce, even if such environments are most interesting to study gully processes, resulting from the complex interaction between soil degradation and erosion, and soil building processes. In this study we extend the database on topographical thresholds for gully head formation through data collection in badland areas and to improve the prediction of gully head development in a given landscape. For this purpose, we selected different badland sites in the Mediterranean that are characterized by different badland morphologies that developed in differed geo-environmental conditions. The analysis of the conditions under which gully heads developed allowed to refine a recently reported gully head threshold equation, and to illustrate how to use the updated model. This model shows that the resistance to gully head formation depends on slope gradient and drainage area at gully heads, land use in the gully catchment at the moment of gully development (expressed numerically by parameters derived from the Runoff Curve Number method), surface rock fragment cover, presence of joints, pipes, and factors/processes affecting soil detachment rate. This study improves our understanding of environmental conditions that control the development of gully heads in various badland types through a combination of field data collection of gully heads and modelling.

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