The use of the slope-area function to analyse process domains in complex badland landscapes

This paper analyses the complex, erosion-prone sub-humid badland landscape in Tuscany (Italy) using the functional relationship between drainage area (A) and slope (S) that charactizes local eroding basins containing calanchi. Given the apparent partial disconnection of landscape elements, the effectiveness of the S-A function to identify local process domains in the calanchi landscape is explored. A series of sub-basins tributary to the Orcia River in southern Tuscany were selected as a suitable study area within which to explore this question, given its representativeness of complex Mediterranean calanchi landscapes, and the availability of multiscale Digital Terrain Models, as well as previous extensive geomorphodynamic local research. The analysis of the S-A plots allowed inference of some important patterns and trends in this unusual landscape, in particular: the S‐A curves showed a general trend comparable with that known in literature but calanchi basin curves generally show higher S values than non-calanchi ones and the initial typical positive S‐A trend is barely evident; ii. denudation processes are better resolved in the total (non-binned) basin plots and calanchi and landslide source areas are often overlapping, highlighting their complex cause‐effect relationship; iii. a morphoevolutive sequence, linked to the changeable hillslope to channel connectivity, is suggested for the development of within-landslide calanchi, contributing to the disentanglement of geomorphological signatures in this complex, temporarily disconnected terrain.