Volume XVII |

Arch dam failure preliminary analysis using HEC-RAS and HEC-GEO RAS modeling. Case study Someșul Rece 1 reservoir

Abstract: This paper presents a preliminary analysis/simulation of the Someşul Rece 1 dam breaking scenario, from the homonym hydrographic basin, located in the north-eastern part of the Apuseni Mountains, at a 0.1 % probability tributary flow rate calculation. The study of the floodplain areas, that occur after the failure of the Someşul Rece 1 dam, was achieved with the help of 1D hydrological modelling. This type of modelling is one of the most complex (Cameron et al., 2006), involving both, the definition of a model with temporal evolution of the dam rupture, and the simulation of a unsteady flow stream in the downstream sector. For the dam analysed area and the downstream sector, several scenarios and modelling of hydrological systems was achieved, with the help of HEC-RAS 5.0.3 software, developed by the Hydrologic Engineering Center (U.S. Army Corps of Engineers).
This free software is the most widely used worldwide in the domain, particularly by the official agencies, having a continuous development, given by the involvement of specialists. The software simplifies the problem of hydrodynamic modelling, due to the limitation to a 1D model. Because the flood obviously has a spatial character, GIS software (ESRI ArcGis with the HEC-GeoRAS extension) were used in determining and defining the hydrographic elements (channel, talweg, banks etc.) and, also, in the representation of the results. Maps of the flood-prone areas have been developed, maps which indicated the magnitude of the estimated accidental flood downstream. The results of the simulation were also used to determine the anticipation time.

Volume XV |

Exceptional floods in small basins in North-Western Romania and the induced effects – Bârsău River, Maramureș county

Abstract: The study aims to analyse floods from May 1970, June 1974 and May 2015, which occured in the Bârsău catchment area, one of the right tributaries of the Someș River. The junction between these two rivers is downstream of Satulung locality in Maramureș County. Bârsău catchment area is located between the Someș and Lăpuș catchment areas and has a surface of 152 km2. The floods of the Bârsău River are fast and have a very short propagation time. They are caused both by rainfalls and snow melting. This is the case of the flood from May 1970, which had a duration of two days, whereas the floods from June 1974 and May 2015 occured just because of heavy rainfalls. From the three analyzed floods, the May 2015 flood, with a pluvial origin, reached the maximum level of 220 cm (DL+20 cm) at Buciumi gauging station and its effects strongly affected local people. Thus, the damages in the villages located inside the basin were recorded first, then quantified. After that, there were made the integrating maps of the flood prone areas as well as the hydrological and associated risks in order to identify areas with different degrees of vulnerability.