Seite - 1142 - in Book of Full Papers - Symposium Hydro Engineering

scenarios allowed for the design of (temporary) mitigation measures to improve the runoff conditions (lowering of water levels, lower surface erosion, etc.) in the areas where flood risk could increase during the construction. At the construction pit edges the risk of influx of water into the pit was studied to support the analyses of the design engineer regarding the justification of the degree of protection, i.e. to preserve the construction pit dry. The final decision was reached based on the relevant impacts of the separate interventions as well as on the impact of all the interventions together on the runoff conditions in the following combinations of the Sava and Krka discharges: Steady flow for simultaneous occurrence of discharges Q20,Sava = 2900 m3/s and QKrka = 80 m3/s. and Steady flow for simultaneous occurrence of discharges Q100,Sava = 3750 m3/s and Q20,Krka = 453 m3/s. The Sava River discharges are taken from the hydrological study from 2011 [7] and the 20-year return period discharge of the Krka River after the study from 2004 [8]. 4. RESULTS AND DISCUSSION – BREŽICE HPP Based on the calculations, the impact of the intermediate conditions during the construction was determined by comparing the water levels in the characteristic points, as a difference between the situation during the implementation of the individual phases and the condition prior to the start of construction. According to the various land uses and other boundary conditions, water levels were compared in 43 points in the Brežice impact area (Figure 6). Fig. 6: Locations of points where the water levels were compared to identify the impact of the construction pit and the diversion channel during high-flow conditions 1142