Arno Riverbed Survey in Florence 1935 - 2019: From the Integrated Survey to the Geomatic Monitoring

On the 50th anniversary of the 1966 flood, the University of Florence, together with many other institutions, promoted the “Florence 2016 Project” by collecting materials, launching new research activities, supporting projects and events to obtain tangible results for the prevention of future disasters and identify good practices for the protection of people and of cultural, economic and environmental heritage. The paper aims to review how the Arno Hydrographic Office surveyed the river during World War Two by photogrammetry and classical topography and to compare the old surveys with the recent activities carried out as part of the Florence 2016 Project. By considering past and more recent surveys, it is possible to identify methodological approaches that retain their validity and to highlight the potentialities of innovative technologies that offer new perspectives for investigation and analysis. In particular, GNSS (Global Navigation Satellite Systems) techniques offer an easy solution to survey georeferencing, with an evident advantage in repeatability and comparison of results, but a high precision survey needs a critical approach, so to aim at effective monitoring.