Abstract
Drought is a complex phenomenon with high spatial and temporal variability. Water scarcity has become a growing problem in Slovenia in recent decades. Therefore, the spatial and temporal variability of hydrological drought was investigated in this study by analysing the Standardized Streamflow Index (SSI). Monthly discharge data series from 46 gauging stations for the period 1961–2016 were used to calculate SSI values at five different time scales (1, 3, 6, 12, and 24 months). The results indicate that the frequency and intensity of droughts in Slovenia has increased in recent decades at most of the analysed gauging stations and at all time scales considered. Spring and summer periods were identified as critical in terms of water deficit. SSI values vary independently from the location of the gauging station, confirming that drought is a regional phenomenon, even in a small country such as Slovenia. However, SSI values vary considerably depending on the time scale chosen. This was also confirmed by the results of the hierarchical clustering of the number of extreme droughts, as various time scales resulted in a different distribution of gauging stations by individual groups.
Highlights
Drought is a complex natural hazard, connected with water scarcity that affects ecosystems and society [1]
Standardized Streamflow Index (SSI) values were calculated for five different time scales: one month (SSI-1), three months (SSI-3), six months (SSI-6), twelve months (SSI-12), and twenty-four months (SSI24) for the period 1960–2016 for 46 selected gauging stations in Slovenia
The results of the SSI values for the Polana I (1220) gauging station (Figure 2) clearly showed that the frequency and intensity of droughts increased in the last two decades, i.e., a fact that can be observed at all considered time scales
Summary
Drought is a complex natural hazard, connected with water scarcity that affects ecosystems and society [1]. It is a long-term recurring phenomenon that usually affects larger regions and can cause severe damage and economic losses as well as loss of human lives (e.g., [2,3]). Spatial and temporal characteristics of droughts vary significantly [2]. Drought is hard to define, monitor, and qualify. According to Wilhite and Glanz [4], drought can be classified into four types, namely meteorological, agricultural, hydrological, and socioeconomic. Some other researchers have included other factors of atmospheric, ecological, or water management (e.g., [5,6,7])
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
