Short-term channel adjustments are a research topic of great relevance in the framework of fluvial geomorphology, but studies on this topic have been quite scarce in Southern Italy, at least since the 2010s, notwithstanding the fact that this area is strongly representative of
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Short-term channel adjustments are a research topic of great relevance in the framework of fluvial geomorphology, but studies on this topic have been quite scarce in Southern Italy, at least since the 2010s, notwithstanding the fact that this area is strongly representative of a much wider morphoclimatic context, i.e., the Mediterranean area, which particularly suffers from the effects of current climate change. Currently, different interpretations still exist about the type and role of controlling factors, and a common morphoevolutionary trend is quite far from being defined; so, new case studies are needed. In this paper, the geomorphological changes experienced by the Sabato R. (Southern Italy) over a period of ~150 years were investigated. A reach-scale geomorphological analysis in a GIS environment of raster data, consisting of four topographic maps (from 1870, 1909, 1941 and 1955) and five sets of orthophotos (from 1998, 2004, 2008, 2011 and 2014), was carried out, integrated with field-surveyed data. Land-use changes, in-channel anthropic disturbances, floods and rainfall variations were selected as possible controlling factors. The study highlighted four morphoevolutionary phases of the studied river. Phase 1 (1870s–1910s) was characterized by a relative channel stability in terms of both mean width and pattern, while channel widening dominated during Phase 2 (1910s–1940s). In contrast, Phase 3 (1940s–1990s) was characterized by intense and diffuse narrowing. Finally, during Phase 4 (from the 1990s onward), an alternation in channel narrowing and flood-induced widening was detected. During all phases, changes in both channel pattern and riverbed elevation were less evident than those in channel width. Land-use changes and, later, floods, in addition to in-channel human disturbances at a local scale, were the main controlling factors. The obtained results have profound implications for rivers located outside Italy as well, as they provide new insights into the role played by the considered controlling factors in the geomorphological evolution of a typical Mediterranean river. Understanding this role is fundamental in regional-scale river management, hazard mitigation and environmental planning, as proved by the vast pre-existing scientific literature.
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