GPS-based high resolution mapping techniques in the Arno river for a correct flood risk management

An extensive high-resolution GPS mapping survey has been carried out over the entire course of the Arno river within the Florence province (62km on each river’s bank) in order to create a GIS database containing all the natural, urban, hydrological and morphological elements around the Arno and its principal tributaries within the Florence urban and suburban area. The purpose of this project is to provide local public administrations with an helpful tool for managing hydrological risk, hydraulic policy and urban planning. The geodatabase includes artificial and natural elements such as railways, roads, buildings, assets, bridges, administrative boundaries, hydraulic works, drainage outlets, dikes, hydro-morphological elements (such as bars or eroding banks) and so on. All the mapped elements were georegistered and provided with alphanumerical descriptions, including the present condition of all elements, in order to plan ordinary and extraordinary maintenance works. The spatial location of the elements is very accurate (less than ±5cm error both in plan and in elevation), with special attention to the accurate positioning for all the elements of flood containment, both natural (riverbank line) and artificial (dikes or walls). Such a complete and accurate database contains all the elements connected with the fluvial dynamic and with the hydraulic risk and will provide very accurate topographic and geometric data to be used in hydrological models. Moreover, in our opinion, realistic assessments concerning hydraulic risk and flood inundation cannot be obtained only with geometrical and topographical criteria (as currently happens with the Arno river), but should also include an evaluation of the stability of the dykes, most of which are old and have been built using heterogeneous materials in the period between First and Second World War. For this reason, the database has been integrated with geotechnical analyses and numerical modelling carried out on a test site along the Arno river course in order to establish a preliminary assessment of the criteria to evaluate dikes stability at large scale. The extension of such methodology to the whole mapped Arno dikes could provide in the near future a first attempt at integrating geotechnical dikes stability schemes into hydrological models for the prediction of flood risk

Utilizzo di dati telerilevati nella mappatura e nel monitoraggio dei fenomeni franosi e nell’analisi della suscettibilità da frana

The recent advances in the optical satellites capabilities (e.g. high spatial resolution, stereoscopy), the development of new robust techniques based on the interferometric analysis of radar images, such as the Permanent Scatterers (PS) and the possibility of integrating these data within a Geographical Information System (GIS) have dramatically increased the potential of remote sensing for landslide investigations. The Arno river basin (Italy), with a spatial extension of about 9131 km2, has been chosen a as test area for the presence of a relevant number of mass movements (27270 landslides have been mapped by the institutional authorities by the end of 2004) and for its significance concerning the Italian Apennine territory. The aim of the research was to integrate the inventory maps produced through traditional methods with the information derived from the Permanent Scatterers standard interferometric analysis. The spatial significance of the PS point measures (about 600000 PS for the whole Arno river basin), also in terms of geological and geomorphological interpretation, was inferred with the help of optical satellite images and aerial-photos. This approach allowed the mapping of new unstable areas or the modification of boundaries and state of activity of existing landslides. The standard PS analysis was also employed for the validation of a statistically-based susceptibility map of the Arno river basin, through the analysis of predicted susceptibility over the areas identified as new landslides by the PS analysis. An advanced PS analysis, capable of detecting the time evolution of single important mass movements, was also applied over 4 test sites. The results for the Chianciano landslide are in particular presented. The integration of the advanced analysis with on siteal monitoring confirmed the inactivity of the principal landslide body but it revealed the presence of two possible minor movements

High resolution mapping for the management of the fluvial dynamics in intensely urbanized areas

High resolution mapping for the management of the fluvial dynamics in intensely urbanized area

L'ambiente della Toscana nelle tesi di laurea in scienze naturali

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 , Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal