Badlands denudation "hot spots": The role of parent material properties on geomorphic processes in 20-years monitored sites of Southern Tuscany (Italy)

Some monitoring stations have been recording for 20 years the geomorphic processes acting on calanchi and biancane badlands located in the Tyrrhenian side of Central Italy. Field monitoring was aimed at studying the dynamics of surface processes, such as sheet, rill and gully erosion, shallow landsliding, piping and tunneling, considering their space-time variability as a consequence of both natural factors and human pressure. This paper shows the results of grain size, geochemical and mineralogical composition of parent materials from Upper Orcia Valley sites (Southern Tuscany), to further elucidate the role of their properties on processes acting on both bare and vegetated surfaces. Parent materials properties are discussed with respect to the initiation and development of different badlands processes. In particular, clay dispersivity at different depths in the sample sites is examined as a well-known controlling factor of accelerated erosion, thus providing some interesting clues for understanding the spatial variability of denudation rates in the considered badlands sites. (C) 2012 Elsevier B.V. All rights reserved.