Preliminary results in assessing flood-prone areas using UAS System within the Ozana River Upper Basin (the Eastern Carpathians)

The UAV technique, and more recently UAS systems, play an ever important role in various domains of research and practical activities. The increase in number of publications focusing on their applicability is spectacular. The objective of this study is to highlight the efficiency of an integrated command-overflight-taking photo system, in an area with obvious problems related to hydric hazards and risks. The quasi-circular shape, the petrography of the upper Ozana basin, its orientation and its opening to the air masses predominantly movement direction, represent just a few of the reasons why it was chosen as the case study. Also, the settlements are displayed on the valleys thread, and this confluence has a remuu potential, in case of isolated rains in the two related subbasins. The UAV Phantom 4 quadcopter, the UAS system, the DroneDeploy application, the UAVPhoto application, the Visual-SFM application, the Daisy algorithm, the micro triangulation network (mesh), the work surface textures, a hyper-resolution of orthophotoplan, DSM model with a 5 cm resolution etc. are the technical elements that made modelling at a very high detail possible. The probability flow rates that were used, were provided by the two hydrometric stations located very close to the study area. Theywere calculated using professional applications approved at the national gauging network level, using the established Krițki-Menkel and Pearson III statistical distributions. The cross-section profiles was performed in the 10.x ArcMap module, using the 3D Analyst extension, and the hydraulic calculation to obtain the average velocity was done using the Manning equation; subsequently, the floodable surfaces was delineated on these profiles. Using the same ESRI module, the flood prone area polygon interpolation and it overlapping over the terrain model and over the orthophotomap were achieved. Paradoxically, the analysis of the results indicates a low degree of the anthropogenic habitat damage, but this aspect is due, in large measure, to the intervention of technical teams in the recalibration of the minor riverbed, massively clogged by alluvial transport.