USING GIS METHODS FOR MODELLING EXCEPTIONAL FLOOD EVENTS IN BASEU RIVER BASIN, NE ROMANIA

Abstract

The Baseu catchment basin is situated in the northeast of Romanian and it is a right-side tributary of the Prut River. At the end of spring the most significant floods occur on the Romanian territory. They are due to the maximum amounts of rainfall and to snow melting. The phenomenon is also specific to the Baseu catchment basin. The last 20 years have witnessed a change in temporal manifestation, with maximum intensities during the summer (the months of July and August) when heavy rainfall is recorded. In the last 40 years, several critical episodes occurred, which endangered the lives of 79,000 inhabitants. In order to assess the hazard associated with maximum runoff, a floodable stripe with an assurance of 1% (once every 100 years) was modelled. Flood modelling involved the manipulation in GIS setting of the parameters of digital elevation model (DEM) and of their relations with the hydrological system. The main objective of the study is the modelling of an exceptional flood with a probability of 1%, similar to the one of 1969, when the Stefanesti gauging station recorded a flow of 330 m/s. Based in the analysis of the hydrological data spanning over 50 years, recorded at three gauging stations, a maximum flow of 248.1 m/s was determined (the Stefanesti gauging station), using the Pearson III probability curve. The findings have highlighted the significant vulnerability of the human settlements situated in the flood plain of the Baseu River. A surface of 17,000 ha would be flooded, accounting for around 17.5% of the total basin surface.