Abstract: This paper presents a hydraulic analysis of unsteady flow due to a possible dam break of the Tribistovo reservoir located in the Municipality of Posušje, Bosnia and Herzegovina. Flood wave propagation is calculated and flood maps are derived for different dam break scenarios. The methodology adopted for the development of the flood wave propagation model is based on the use of available tools for collection, processing and graphical display of geospatial data and tools for hydrodynamic modeling of transient flow. The selected approach is conservative and results are, as a rule, the worst case scenarios. Flood areas are obtained on the basis of hydraulic calculations with the most unfavorable assumptions: maximum water level in the reservoir, maximum inflow in the reservoir (with the return period of T = 10 000 years), instantaneous/gradual and total dam break, all of which result in extreme flooding.
Keywords: flood wave propagation, dam break, Tribistovo reservoir