Analysis of floods in the upper course of the Hron River in 1930-2010

BLAHUSIAKOVA, A, MATOUSKOVA, M. (2012): Analysis of floods in the upper course of the Hron River in 1930-2010. Geografie, 117, No. 4, pp. 415-433. - The main focus of this research is concentrated on the flood analyses in the upper course of the Hron River in the period 1930-2010. The study includes an evaluation of the flood seasonality, frequency and extremity in two periods 1930-1991 and 1992-2009. The year 2010 has been added because of a very high amount of precipitation between May September 2010 which caused extreme flooding. The most extreme flood in the 20th century occurred in October 1974. At the gauging station Banska Bystrica, discharge values reached 560 m(3).s(-1) which corresponds to the 100-year flood. In the last decade, extreme floods occurred in years 2002 and 2010. The main reason for the flooding was an intense rainfall and local storms with high amount of precipitation. The frequency analysis (in equally long periods 1950-1979 and 1980-2009) proved that there is a higher frequency of floods since 1980 (17 in the period 1950-1979 and 27 between 1980-2009). Higher water levels during floods were reached in the period 1950-1979. The summer floods dominate in both observed periods, but winter floods also occurred very often (7 floods in the period 1950-1979 and 12 in 1980-2009). This is due to the hollow relief of the upper course of the Hron River.