Unraveling Hydrological Dynamics: Investigating the Frequency and Occurrence Rate of Minimum Discharges in Bosnia and Herzegovina

Hydrological drought, characterized by prolonged deficiencies in river discharge, presents significant challenges globally, exacerbated by climate change-induced alterations in precipitation patterns. Notably, studies have revealed evolving minimum discharge trends across Europe, yet a research gap persists regarding Bosnia and Herzegovina’s (BH) low-flow phenomena. Here, we investigate minimum discharges in the Una [Van Loon, AF (2015). Hydrological drought explained. Wiley Interdisciplinary Reviews: Water, 2(4): 359–392, https://doi.org/10.1002/WAT2.1085] and Sana Rivers, filling a crucial void in regional low-flow research. Through comprehensive sensitivity analysis and novel trend analysis methods, we identify significant temporal variations and trends in minimum discharges, particularly during winter and summer seasons. Our results indicate distinct patterns in occurrence rates, with the Sana River experiencing notable increases in extreme events during winter. For example, the Sana River witnessed an increase from 15 documented M1 events in the period 1961–1970 to 28 events in the period 2011–2020. Conversely, while the Una River demonstrates stable trends, the Sana River exhibits a significant decrease in severe events. For instance, the occurrence rate of severe events (M2) on the Sana River decreased from six documented events in the period 1961–1970 to four events in the period 2011–2020. Climate change emerges as a key driver, influencing temperature, precipitation patterns, and snowmelt timing, thereby impacting river discharge dynamics. These findings underscore the urgency of adaptive water management strategies to mitigate the potential impacts of changing hydrological conditions on water resources and communities in BH.