Drought is a complex natural phenomenon that affects ecosystems and society in many ways. Lack of water in rivers, lakes and groundwater are the causes of hydrological drought; therefore, it is very important to understand its evolution and its recovery.
In the diploma thesis we used data on measured flows at water gauging stations, which are part of the national hydrological monitoring of the ARSO. By examining the mean small monthly flows, we extracted the months in which some watercourses dried up. On a monthly basis, we analysed the number of dry days when there was no water flow in the area of the gauging stations. The results were used to analyse the occurrence of dry spells by year and month over the period 1950-2020 for the operational water-gauging stations.
The results were plotted graphically and compared with rainfall data and the number of days with rainfall in each area. We found that at most gauging stations, the number of dry days is higher in the years of the most severe hydrological droughts, which are characterised by a large deficit in rainfall. At some of the stations considered, watercourse droughts are a regular occurrence that happens almost every year. These stations include Kobilje, Prestranek, Šoštanj, Branik and Podkaštel. Over the last two decades (2000-2020), the Martjanski Stream, which previously did not experience many dry days over a long period of measurements, has also been drying up more and more frequently. The Iška River, which dried up six times in the previous decade, is also increasingly often without flow. At some of the other gauging stations, the droughts are less frequent and have mostly occurred during the driest years.
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