Channel adjustments over 140 years in response to extreme floods and land-use change, Tammaro River, southern Italy

Since the last decades of nineteenth century, Italian rivers experienced remarkable morphological changes. Most of the previously investigated rivers were affected by intense human disturbances, which were frequently indicated as the main control factor. In contrast, the Tammaro River (southern Italy) underwent less complex human interventions than other Italian rivers, at least since the recent closure of the Campolattaro Dam in the median zone of the catchment. Thus, it represents a good example to analyze the effects of changes in climate and land use on short-term channel adjustments. In this paper, the channel adjustments experienced by the Tammaro River over a period of ~140 yr (1870–2011) were investigated. The study integrated results from GIS-based geomorphological and land-use analysis, field surveys, and analysis of hydrological data (rainfall, flow discharges, extreme floods). From the last decades of nineteenth century to the mid 1930s, the river experienced widening and a slight increase in transitional channel morphologies (Phase-1). From the 1930s to the late 1990s, the river underwent a marked narrowing and limited to moderate incision (Phase-2). The geomorphological effects of the 1949 extreme flood were superimposed on the Phase-2 response. Finally, from 1990s onwards (Phase-3), the river experienced substantial stability with respect to the changes during the previous phases and different behaviors at the reach scale. During Phase-3, changes in channel morphology were observed a few years after the closure of the Campolattaro Dam. The morpho-evolutionary phases observed for the Tammaro River were very similar, even if slightly diachronous, to those reported in the literature for more anthropized rivers of southern Italy.