STORMS IN ZGORNJESAVSKA VALLEY IN AUGUST 2003

Abstract

The summer of 2003 was very dry, with drought causing severe damage all over Slovenia. The only exception was the extreme northwestern part of the country, where two severe storm events caused torrential floods and landslides, averaging the rainfall balance of the region at the end of August. Heavy rainfall was limited to a very small mountainous region (about 100 km2) south of Rateče and Kranjska Gora. Cold air in the upper troposphere was the main reason for the strong convection during the first event in the late afternoon of 29 August (Figure 1). The second heavy rainfall event that happened on 31 August (Figure 1) was caused by the passage of a very pronounced cold front over Slovenia. Both convective episodes were intensified by the complex topography of the region. During both events, very high return periods for rainfall intensity were observed (Table 1). A 1-hour intensity had a return period of 44 years, while the highest return period was detected for a 6-hour rainfall intensity (250 years). Abundant precipitation caused severe torrents, which deposited a lot of materials (sand, gravel and wood) in the valleys and triggered landslides.