The paper examines changes in air temperature, precipitation, and river
discharges on seasonal and annual scale over the Sava River watershed in Bosnia &
Herzegovina during the period 1961–2016. Based upon data gathered from 11
meteorological stations and 3 hydrological stations, hydroclimatic variables trends were
established by utilizing the nonparametric Mann-Kendall test and the nonparametric Sen’s
slope estimator. The results show significant positive seasonal and annual trends (expect
for autumn, during which upward trends were insignificant) in air temperature, whereas
both positive and negative insignificant seasonal and annual precipitation trends are shown
where determined for the entire watershed. Most prominent upward trends in air
temperature were found in summer and afterwards in winter and spring, indicating a
pronounced warming tendency over the Sava River watershed. Trends in river discharge
displayed a negative tendency in all seasons. Nevertheless, a majority of estimated trends
of river discharges were weak and statistically insignificant. Throughout the year, river
discharges showed significant positive correlation with precipitation, whilst connection
with air temperature was mostly significant and negative. The study results suggest that
climate is an important factor affecting river regimes, as well as that changes in river
discharges are reflecting recent abrupt changes in climatic variables.
