FLOOD STORMS BETWEEN 21 AND 26 DECEMBER 2009

Abstract

As a result of heavy rainfall from the evening of 21 December to the morning of 23 December, and melting of snow below the snowfall line, the watercourses in the western part of Slovenia increased substantially in the night from 22 to 23 December. Flooding values were almost reached in the upper stream of the rivers Sava and Savinja, and along the rivers Selška Sora, Sora, Ljubljanica and Reka. Floods occurred for a short period of time along the watercourses of the Idrijca river basin, along the entire course of the Vipava river, the Ljubljanica river on Ljubljana marshes, the Kolpa river, in midstream of the Sava river (Ljubljana – Radeče) and the Gradaščica river. The level of the Soča river also increased significantly. In the afternoon the water level of all rivers started to decrease. In the night from 24 to 25 December the rainfall intensified again and was heaviest in the Soča river basin and the Gorenjska region, especially in Bohinj. The most severe flooding occurred along the Soča, Idrijca (mainly the downstream section), the Sava Bohinjka and the Gradaščica rivers, in the upper stream of the Sava river and along the Sava river in the Zasavje region. An unusually extensive flooding occurred on the Ljubljana marshes and in the Vipava river valley. The Kolpa river also flooded, and the water levels of the Sora, Dravinja and Reka rivers increased significantly, causing, however, no major flooding. Except for the downstream of the Sava river where the flooding wave proceeded towards the Krško-Brežice plain, the watercourses started to retreat in the afternoon and evening of Saturday, 26 December, and the situation calmed down.