Lidar for analysis of hydraulic risk territories VINCENZO BARRILE (*), GIUSEPPE M. MEDURI (*), GIULIANA BILOTTA (**) * DICEAM - Faculty of Engineering “Mediterranea” University of Reggio Calabria Via Graziella Feo di Vito 89100 Reggio Calabria, Tel +39 0965 875301 ** Ph.D. NT&ITA – Dept. of Planning - University IUAV of Venice Santa Croce 191, Tolentini 30135 Venice ITALY vincenzo.barrile@unirc.it, ing.giuseppemariameduri@ gmail.com, giuliana.bilotta@iuav.it Abstract: - This paper investigates a possible use of the technique of LIDAR topographic survey for updating existing hydraulic models for the calculation of Hydraulic head for risk areas. The study, in particular, tends to assess the benefits to be gained from new methods of LIDAR detection comparing calculations and simulations of updated models with those obtained from existing models and also highlighting the critical issues of the use made for hydraulic analysis. Key-Words: - Lidar – Hydraulic models – Updating hydraulic models – Hydraulic analysis 1 Introduction A hydraulic model is a logical-mathematical abstraction for studying behavior and evolution of the flow of waterways that allows, through appropriate software, to simulate the propagation of the flood wave along the hydraulic lattice and then determine the height that the water level reaches in the various sections highlighting possible critical of the lattice itself. Generally at the competent institutions are hydraulic models developed on the basis of maps for the reconstruction of the geometry of the waterway and land survey classics, to the party in riverbed with sections made every 100/200 m. In order to make a productive comparison between models obtained by techniques of classical survey and those by LIDAR, the first step of the study involved the modeling with the same software available; therefore, on the basis of the existing topographic survey, we made new hydraulic models, calibrated on the basis of transit times recorded in some major flood events. Fig.1: Orthophoto of stream segment 2 Application of Lidar survey for updating hydraulic model The LIDAR system is a technique for aerial surveying that allows, through the use of an integrated active sensor laser, and GPS and INS for determining position and orientation, the reconstruction of digital models of the surveyed surfaces (DSM) rapidly, with high density of collected points and with planimetric and altimetrical accuracy in the order of 10-30 cm. The waterways are subject to continuous morphological changes both in river morphology that in section because of erosion, transport, sedimentation with the need of a regular update for hydraulic tests. The advantages of using the LIDAR over the execution speed are especially those of the opportunity to obtain a more precise and detailed real-section; the use of topographic classical surveys involves in effect, for reconstructing the geometry of the intermediate portions between the topographic sections, the use of interpolation with a consequent approximate description. In the present discussion, the step of treatment and processing of data from the LIDAR survey we used two filtering algorithms. The first is characterized by a global statistical approach to solving the problem; it uses a particular regressive spatial model said SAR Simultaneous Autoregressive. This approach allows the simultaneous autoregressive estimation both of the trend of the ground surface both of the Advances in Environmental and Geological Science and Engineering ISBN: 978-1-61804-314-6 157