: 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.

Some usual hydrological methods and the hydrological model EBA4SUB are used in the paper to determine the design peak discharge for various return periods for catchments in Bosnia and Herzegovina. The aim of the paper is to test for the first time the EBA4SUB model in the selected catchments. The results obtained by the EBA4SUB model compare well with other related methods. The advantages of the model lie in the fact that it takes into account physical processes taking place in the catchment, influencing formation of surface runoff.

Water management systems and facilities are constructed with the purpose of creating conditions for efficient use of water, protection of water quality and protection from adverse effects of water. Their construction, maintenance and operation require major investments that burden the national economy in large measure. Construction costs of water management systems and facilities significantly depend on characteristics of the water regime, i.e. water regime is the determining factor for planning and implementation of water-related works and activities. Since the activities of planning and design of water facilities and systems often take place in areas with completely unknown or insufficiently known water regimes, the method of regional analysis is often used as the method to define and evaluate the parameters determining the water regime. This paper describes the conducted regional analysis of flood flows for the area of Bosnia and Herzegovina, which involves establishing regression dependences of hydrological water regime parameters and physical and geographic characteristics of catchment areas as the basis for defining the water regime in a particular area.

. A truly important challenge in flood frequency assessment (FFA) in Bosnia and Herzegovina is lack of continuous gaged flow data, because the reliability of FFA results depends on the length and quality of flow records. At the case study location - hydrologic station (HS) Maglaj on the river Bosna the reference period for flow record is 1961-1990. The research goal in this paper is to exploit the water stage gauge data and information (1933-1960) for the extension of flow dataset from 30 to 58 years. We apply the original rating curve from the period 1960-1970 to the water table record to generate daily flow datasets. Anticipating three rating curve change developments, we generate six longer flow datasets -with and without instantaneous maxima, for the period 1933-1990 at HS Maglaj - Poljice. Together with two reference period flow datasets we arrive at the total of eight datasets/scenarios and subject these datasets to FFA on the annual maxima series and partial duration series. For the former, we use conventional statistical analysis (CSA) and for the latter, the peak over threshold (POT) method. The FFA results show no significant difference in the values of the selected quantiles for scenarios involving time extrapolation. The quantiles for the reference period 1961-1990 are generally higher, among both CSA and POT results. We find the absence of instantaneous maxima a major influence on FFA.