Channel width variation phases of the major rivers of the Campania Region (Southern Italy) over 150 years: preliminary results.

In recent decades, rivers in Southern Italy experienced remarkable channel changes. Studies on this topic are relatively recent, and yet, far from defining a morpho-evolutionary trend that is common to all rivers of this area. The types and roles of the different controlling factors are still debated. In this study, we present preliminary results about the width channel changes of major rivers in the Campania region (Southern Italy) in the last 150 years. The aim is to provide new insights that are useful to define morpho-evolutionary trajectories at a regional scale and shed light on the roles played by controlling factors. To this aim, we carried out a GIS-aided geomorphological analysis of topographic maps and orthophotos. The results showed the existence of at least three main phases of channel width variations. Between the 1870s and 1930s (Phase 1), most of the rivers experienced widening. Between the 1930s and late 1990s (Phase 2), all of the rivers underwent dramatic narrowing at high rates. Finally, from the 1990s onwards, no dominant trend was found and variations were negligible. Land-use changes at the basin scale and rainfall changes at a decadal scale are likely the main controlling factors, while variations in human disturbances and local factors seem responsible for changes in general trends.