Page - 1138 - in Book of Full Papers - Symposium Hydro Engineering

retention area, as they could potentially affect the runoff conditions at the border with the Republic of Croatia. In the downstream country such analyses were conducted in public procedures carried out in Integrated Environmental Impact Assessments. In such demanding interventions, the use of numerical modelling only is not sufficient, therefore the hydraulic analysis of the runoff conditions prior to and upon the construction of the HPP chain (Krško, Brežice, Mokrice) involved the use of hybrid hydraulic models [2-4]. By extensive modelling the locations of reservoir levees, size and locations of flood water overflow structures, HPP spillway structures, and other accompanying developments, including roads and economic structures, were analysed and optimised. Fig. 2: Locations of HPPs on the Lower Sava River. HPPs Vrhovo, Boštanj, Blanca, Krško, and Brežice are completed, while the Mokrice HPP is in the final design stage. For the planned situation of the area at the Brežice HPP, where there also is the Krško Nuclear Power Plant (NPP) located at the Sava, it is also necessary to check the fulfilment of all the strict safety requirements regarding the operation of NPP Krško, including the analysis of the conditions during the Probable Maximum Flood (PMF). An overview of the key interventions in the National Spatial Plan area concerning the Brežice HPP is shown in Figure 2. Fig. 3: The run-of-river Brežice HPP facilities with many accompanying measures are shown in terms of the existing flooding situation of the areas along the Sava River between Krško and Brežice at Q100,HW. 1138