Olt is one of the most important rivers in Romania. It springs in the Eastern Carpathians, has a length of 615 km and passes through 7 counties. In the area of Turnu Roşu Defile, the phenomenon of capture takes place: the mountainous Olt, having a lower basin, reaches, through regressive erosion, to attract the waters of the Transylvanian Olt, thus increasing its basin and flow.