Bulgaria's Ministry of Environment has warned of expected rise of river water levels throughout the country on Thursday.
Local flash floods due to heavy rainfalls and increased soil moisture are also possible, Bulgaria's Telegraph Agency reports.
Bulgaria's Institute for Meteorology and Hydrology forecast for Thursday is for rainfalls in many parts of the country, more excessive in the central and eastern Bulgarian regions.
This will lead to significant increases in the water levels of a number of rivers, including Ogosta, Iskar, Vit, Osam, Yantra, Lom, Tundzha, Struma and Maritza.
The operational unit of the Ministry of Environment and Water remains on high alert.