THE WATER LEVEL OF RIVERS IN 2022

Abstract

The water-abundance of Slovenian rivers in 2022 was significantly below average. Compared to the reference period 1991-2020, only two-thirds of the average water amount flowed along the riverbeds. The year as a whole is therefore classified as one of the hydrologically driest years for surface waters in the measurement records. The least water abundant rivers on an annual basis were the rivers in Slovenian Istria, the Reka river and the rivers in the north-east of Slovenia. The only water reaching average abundance was the Kolpa river basin, because of floods in this area in September and December. The water level conditions of Slovenian rivers had already been below the reference period average since July 2021 and persisted as such until mid-September 2022, which represents one of the longest episodes of its kind since 1961. In September low water conditions were interrupted by two episodes of floods, mostly in the Kolpa, Krka, Ljubljanica and Sora river basins. Another flood event, mostly in the same river basins, occurred in December. This one also included the Vipava River basin, but it was less intensive than the first two. The classification of the 2022 mean annual flows into the percentile classes of the reference period 1991-2020 shows that, with the exception of the Kolpa river, the mean annual discharge of most Slovenian rivers was less than the 25th percentile (25% probability of occurrence in an individual year). The rivers Rižana in Kubed, Savinja in Nazarje, and Drava in Črneče exceeded the lowest mean annual discharges in the measurement record. The Mura river had the second-lowest mean annual discharge; only in 2003 was it lower. The karst fields were flooded from September until the end of the year, but for a shorter period than usual.