Anthropocene erosion dynamics and sediment connectivity in a central Italy landscape with badlands

In the Mediterranean region, natural soil loss susceptibility is enhanced by human pressure, that has a long history and seems to be the main driver of changes in sediment supply during the Anthropocene. Badland areas in non-arid landscapes can be ideal sites to investigate the role of human activities in triggering erosion processes in the current context of global change, as their origin has been related to scenarios of widespread land degradation. So far, little attention has been given to the relationship between slope processes and river morphodynamics in badland landscapes. In this context, the exploration of sediment connectivity can be informative, considering the rapid morphoevolution and consequent off-site effects.

Anthropocene hillslope morphodynamics and sediment connectivity within a representative badland area located in southern Tuscany (Italy) was explored, in order to better delineate the recent erosion dynamics. The relative importance of the role of man activities in the medium-term landscape evolution and how far it can be connected to the triggering and/or mitigation of hillslope processes is discussed.

In order to achieve these general purposes, the research approach included i) a multitemporal survey of the erosion dynamics at catchment scale, ii) the analysis of the land use changes during the last century and iii) the geomorphometric indexing of the structural connectivity of a representative catchment located in the Upper Orcia River valley, starting from a 1 m resolution DEM (Digital Elevation Model) derived from LiDAR (Laser Detection and Ranging).

Starting from the mid-20^th century, the area has been subjected to artificial reforestation with conifers (performed mainly on upland areas), impressive land reclamation (many badland areas have been levelled due to the enlargement of croplands), pasture decrease as a consequence of rural land abandonment, with the subsequent increase in the vegetation cover. Everything merges with a recent reduction of hillslope denudation rates, that can be related to the observed channel adjustments during the last decades.

Outcomes of this research can be useful for a deeper comprehension of the effects of man-induced changes on the slope-channel systems and, in a wider context, can be helpful for supporting the decision making in a perspective of sustainable development.