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The use of the slope–area function to analyse process domains in complex badland landscapes
Author(s) -
Vergari Francesca,
Troiani Francesco,
Faulkner Hazel,
Del Monte Maurizio,
Della Seta Marta,
Ciccacci Sirio,
Fredi Paola
Publication year - 2019
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.4496
Subject(s) - landslide , geology , terrain , tributary , fluvial , drainage basin , physical geography , geomorphology , hydrology (agriculture) , structural basin , geography , cartography , geotechnical engineering
This paper explores the effectiveness of the widely‐used functional relationship between drainage area (A in m 2 ) and slope (S in m/m) to identify local process domains and aid interpretation of process interactions in a complex badland landscape. In order to perform this investigation, a series of sub‐basins tributary to the Formone River in the Orcia catchment (central Italy) were selected as a suitable study area within which to explore our questions, given these basins' general representativeness of local terrain, the availability of a high resolution digital terrain model and previous extensive geomorphological research. Eroding basins containing both calanchi and landslides are common in the sub‐humid badland landscape of central Italy, where field observation identifies a complex pattern of erosive processes associated with a history of uplift, despite which parts of the local landscape appear disconnected. Results reveal that the shape of all S–A curves (plotted using S data binned on log A) is comparable with that described in the literature, although sub‐basins containing calanchi generally plot with higher S values than non‐calanchi ones, except in the ‘fluvial’ section of the plots. Second, when viewed on total data (non‐binned) S–A plots, landslide source area domains and calanchi domains are entirely coincident in all basins, supporting a cause–effect relationship. Additional plotting of the frequency characteristics of the raw data in a new way supports the interpretation that calanchi frequently initiate in landslide scars. In general though, although the S–A plots can contribute to the disentanglement of geomorphological behaviour in some complex erosional landscapes, it became apparent that in this landscape, process domains do not separate out with clarity along the A axis as suggested by theory. Despite this, an alternative, broader‐scale morphoevolutive model can be proposed for the development of within‐landslide calanchi, driven by changes to basin connectivity to the base channel. © 2018 John Wiley & Sons, Ltd.