Quantifying the impacts of the human activities on the evolution of Po delta territory during the last 120 years

Our study investigates the land use evolution of the Po River Delta (Italy, about 18,000 ha) over the last 120 years to evaluate the impacts of human activities. The various land uses and their evolution have been evaluated through the analysis of different historical maps and aerial photographs. The land use maps have been realized using the third level of the Corine-Land-Cover (CLC) legend. The assessment of the anthropic pressures on the evolution of the territory has been done by expert's judgment on the impact of the different land uses on natural environment. From 1894 to 2015, the land use change is mainly characterized by a conversion of the natural wetlands into agricultural areas, and fishing valleys classified as artificial wetlands in the period between 1892 and 1978. As a result of agricultural and economic policies, agricultural practices became a major driver of wetland loss, and then the urbanization related to agricultural settlement had provided additional impacts on wetland loss. Scientists and technicians indicate that industrial/commercial and harbour related activities are the most important factors that contribute to the degradation of the land use, while, positive impacts have been attributed to natural land use and in particular lagoons, forests and green areas. The cumulative human impact maps show that more than 50% of the territory is degraded during the following three periods: i) a first period (1894-1955) of good environmental conditions mainly due to the presence of highly positive ecological systems; ii) a second period (1955-2000) of intense degradation along coastal areas and the transportation roads; iii) reduction of degradation processes. Finally, we believe our methodology represents an effective geospatial approach in land management: the map of human pressures and the involvement of the experts highlight to managers and policy-makers the impacts of human activities.