HYDROLOGICAL ANALYSIS OF HIGH WATERS AND FLASH FLOODS OCCURRED IN SEPTEMBER 2007 IN SLOVENIA Mira Kobold, Mojca Sušnik, Mojca Robič, Florjana Ulaga, Bogdan Lalić Environmental Agency of the Republic of Slovenia Vojkova 1b, Ljubljana, Slovenia
[email protected] Abstract Heavy and abundant precipitation which captured the western, north-western and northern parts of Slovenia on 18 September 2007, caused quick rise of river discharges especially in the region of Baška grapa, Davča, the Cerkljansko and Škofja Loka hills. In that area the streams Selška Sora, Davča and Kroparica caused real destruction. The torrential streams and rivers flooded also in the region of Karavanke and foothills of the Kamnik-Savinja Alps, Kranj and Domžale fields, the Tuhinj valley and extensive Celje region. The Savinja was high in the middle and lower stream. The discharges of the tributaries Hudinja and Ložnica exceeded 100- year return period. The Dravinja flooded in the middle and lower stream. The return period of flood was between 50 and 100 years. On the most affected area the peak discharges exceeded the periodical maximum discharges measured at the water stations. The Sava was high mostly because of the high tributaries of the Sora, Bohinjska Bistrica, Lipnica, Tržiška Bistrica, Kamniška Bistrica and Savinja. The return period of the flood wave was around 20 years. Besides flooding many landslides were triggered, what is usual for Slovenia at such hydrological situations. The result of this catastrophe was enormous economic damage and loss of six people's lives. Keywords: flash flood, precipitation, HEC-1 model, return period, hydrograph, runoff coefficient, September 2007.