Author(s):
1. Slobodan Gnjato, University of Banja Luka, Faculty of Natural Sciences and Mathematics, Republic of Srpska, Bosnia and Herzegovina
2. Tatjana Popov, University of Banja Luka, Faculty of Natural Sciences and Mathematics, Republic of Srpska, Bosnia and Herzegovina
3. Goran Trbić, Republic of Srpska, Bosnia and Herzegovina

Abstract:
One of the key issues facing modern society is water scarcity. Hydrological drought is a natural phenomenon characterized by a prolonged period of below-normal water availability, during which water resources may become insufficient to meet existing demands. The main goal of this study was to assess hydrological drought of the Trebišnjica River. To determine hydrological drought of the studied river, we applied the Streamflow Drought Index (SDI) and calculated annual, summer (April-September) and winter (October-March) SDI values. The index was computed using mean monthly streamflow data from the Grančarevo gauging station for the period 1961–2025. Subsequently, the Mann–Kendall trend test was applied to assess temporal changes in SDI values over the study period. Our analysis revealed two long-lasting distinct drought episodes that can be identified between 1988/89 and 2002/2003 and between 2014/2015 and 2024/2025. SDI values remained predominantly negative throughout these periods, with several pronounced deficits observed in 1988/89 (–1.71), 1989/90 (–1.85), 1992/93 (–2.15), 2001/2002 (–1.73) and 2016/2017 (–1.87). The Mann–Kendall test results show a decreasing trend of annual and seasonal SDI values, whereas significant decreasing tendencies were found for the annual and summer values. Overall, our findings suggest a shift in hydrological conditions in the Trebišnjica River towards increasingly dry conditions.

Key words:
drought,Streamflow Drought Index,Trebišnjica River,Bosnia and Herzegovina

Date of abstract submission:
20.08.2026.

Conference:
Contemporary Materials 2026 - Savremeni Materijali