Sustainability of the River Environment Related to Hydro-Chemical Stresses of Sewage Treatment Plants in Chienti and Potenza Rivers (Central Italy)

The concept of Landscape Sensitivity is now more topical than ever, given the intense stresses associated with increasing hydrogeological instability because of strong anthropic pressures and extreme climatic events. One of the environments most affected by anthropogenic stresses and catastrophic weather events is undoubtedly the river environment. Studies conducted in the river plains of the Marche region in Italy, starting from the second half of the last century till today, have shown that the deepening of the riverbed is of a maximum of 10 m in the main river channels. Subsequently, these incisions were amplified by the massive impermeabilization of the floodplains and by works in the riverbeds, built to prevent erosion. In the basins of Chienti and Potenza Rivers, the downcutting was about 4–8 m, compatible with the averages of the Marche region rivers for the same period. These deepenings were subsequently amplified, starting in the mid-1980s, with the construction of sewage treatment plants near the main watercourses. In many cases, erosion phenomena, both lateral and vertical, have been observed, sometimes triggering landslide movements in the proximal banks. The analyses made it possible to highlight that this imbalance in river dynamics is due to the convergence of physical processes, such as the increase in discharge, and chemical processes that produce alteration of clay minerals related to surfactants and other chemical pollutants. This study represents a first attempt to highlight a little-known issue that could influence river sustainability of areas subject to significant anthropic pressures.