ENVIRONMENTAL CHANGES CAUSED BY HUMAN ACTIVITY AND CLIMATIC CHANGE, DURING LAST 40 YEARS, IN A RIVER BASIN (ITALY): LINK WITH DESERTIFICATION RISK

The purpose of this study is to investigate environmental changes occurred in the last forty years, due to agriculture and climate change, in a river basin (Senio) representative of many Italian areas, and linkages with the risk of desertification. The work considers the soil use variations, changes in agricultural crops and changes in water reservoirs, through aerial and satellite images of the years 1972 and 2003, finally compare present-day catchment budget for the Senio river with an estimate of the 1972 catchment budget. The Senio basin is a typical landscape of North East Apennine (Italy): the clayey lithology is dominant and it is considered hydrogeological risk, the summer is dry and the agriculture is intensive. It is also a typical example of the history of the Apennine landscape, where two phenomena occurred in the Apennines from the 50s until nowadays: the persons moving to cities and valley and the agricultural mechanization. The consequences are evident on land use: abandonment of less productive fields and enlargement of the remaining fields to allow mechanization. Moreover in the half of XX century were carried out numerous of land reclamation for water control, for soil defence and for the water storage. The study shows a relationship between variations in the time of water reservoirs and the extension and kind of crops variations: in the '70s, the reservoirs had mainly a hydraulic purpose of regulation and surface runoff control and for livestock use. During the last years the new water reservoirs are made near the torrent, they are changed both in size and building characteristics in order to sustain the growing irrigation demands. This critical situation has worsened with the introduction in the 80s with high water needs crops, fruit trees and especially the kiwi (Actinidia). In addition to these changes caused by human activity, it must also consider the climatic variation observed, in particular the increase in average temperature of 1,1 °C (1991-2008). The direct consequence of these changes have greatly reduced the flow of the river Senio. For these causes the basin is considered to desertification risks.