Improving flood risk map accuracy using high-density LiDAR data and the HEC-RAS river analysis system: A case study from north-eastern Romania

North-eastern Romania is frequently affected by storms that produce annual floods with catastrophic effects upon agriculture areas. The implementation of the 2007/60/ EC Directive, which aims, among other things, to assess and manage flood risk, is currently being carried out by means of rough hydrological risk maps. Additionally, the limits of the potentially floodable areas generated on digital elevation models with 30 points/m resolution (SRTM) do not correspond to the current topographic reality. Three tests (T1, T2, and T3) for modelling the floodplains and the comparative assessment of potential damages in the case of 30 localities in the study area (Baseu River basin) were carried out in this study. The results indicate that official data (T1) underestimate potential damage in the case of hydrological events with a recurrence interval probability of 1% (100-year). The T2 [1%] (100-year) results also highlight the role of hydro-technical works in mitigating floods. In T3, the hydrological risk areas were generated with an accuracy of 0.5 m, evaluating the probable damage in cases of events with probabilities of 3% (33.3-year), 1% (100-year), and 0.1% (1,000-year) recurrence intervals. The accuracy of the official hydrological hazard maps (T1) was improved using high-density LiDAR data and HEC-RAS software (T3).