Long-term streamflow trends in Bosnia and Herzegovina (BH)

The paper investigates streamflow trends in Bosnia and Herzegovina (BH). Long-term (1961-2020) average annual and monthly streamflow trends were elicited on the basis of data from seven hydrological stations which are positioned on most of the largest rivers in BH. Trend disclosure was conducted by utilizing the Mann-Kendall (MK) test, the modified MK (mMK) test, and the Sen's slope estimator (SSE). The decreasing trend in annual streamflows is present across all studied rivers in BH in the range from - 0.07 to - 0.84 m(3)/s/year. Significant negative tendencies in summer months (June, July, and August) streamflows were determined at almost all stations. July is the month in which significant negative trends were recorded at six out of seven stations (- 0.11 to - 0.66 m(3)/s/year). The insignificant negative tendency was, in general, present throughout the year, whereas negligibly positive trends were present during March and October at a couple of stations. The Rescaled Adjusted Partial Sums (RAPS) analysis revealed that 1981/1982 was the year when most hydrological stations started exhibiting negative streamflow tendencies. Our results point out that the water resources of BH require sustainable management and that this is one of the essential tasks for decision-makers at both the state and local levels Also, this study represents the starting point for further research in water resources, given that so far this is the first and most comprehensive long-term analysis of average streamflows at the national level of BH.