Torrential flood risk assessment and environmentally friendly solutions for small catchments located in the Romania Natura 2000 sites Ciucas, Postavaru and Piatra Mare

Abstract The management of torrential flood risk areas located in natural protected sites requires special approaches. Also, those processes can cause casualties and damage socioeconomic structures (roads, railways, houses, etc.) The processes intercept protected landscapes, sometimes endangering protected species and habitats. The restoration of the streambed's stability in protected areas and the protection of the economic objectives affected by the torrential floods, imply special measures of planning. The planning measures are based on the use of ecological materials and technologies with minimal impact on the environment. The article presents a methodology for identifying small river basins with high torrential risk and the endangered economic objectives, as well as applying this methodology into three Natura 2000 sites from central Romania (ROSCI0207 Postavaru, ROSCI0195 Piatra Mare and ROSCI 0038 Ciucas). Identification of the basins was made considering their geomorphological and hydrological characteristics and the vulnerability of the intercepted socio-economic objectives. Into identified watershed, measurements of the streambed topography and the geometric characteristics of the endangered structures were made. Based on hydraulic simulations, maps were generated for floods with a 100-year return period. Using these flood maps, the maximum water level was determined to highlight the flood risk areas for each socioeconomics structural objective. In areas identified as floodplain, special structural and nonstructural solutions are proposed for guiding water into convenient paths to avoid the endangered structures.