Seite - 1145 - in Book of Full Papers - Symposium Hydro Engineering

Fig. 8: Photograph of the construction pit site and the diversion channel during high water in September 2014 (discharge approx. 2000 m3/s) (source: 24ur.com). The surface water formations confirmed the accuracy of the hydraulic analyses. During the event at locations under higher pressure//load//burden due to spiral water current in the diversion channel some erosion damage was caused in the banks of the diversion channel, while the safety of the construction pit was not at risk. 4.2. CHANGES IN RUNOFF CONDITIONS IN THE INDIVIDUAL PHASES OF CONSTRUCTING EMBANKMENTS AT BREŽICE HPP The calculated conditions for the situation with the construction pit and the diversion channel provided a starting point when trying to find the best sequence of constructing embankments along the reservoir, i.e. such that would minimise any further negative impact on the situation, or even mitigate the situation, particularly along the Ljubljana–Zagreb motorway. The condition prior to the start of works at HPP Brežice provided another basis. The selection of various sections of the dike, various building sequences, etc., provided several scenarios, of which 16 cases were analysed, which addressed the individual developments or temporary conditions in space. Due to their extensiveness, the descriptions of the variants are not provided here. Roughly, they can be divided into four phases as follows: (1) Construction of embankments upstream the weir; (2) construction of embankments from NPP Krško downstream and construction of a flood control relief system; (3) construction of embankments in the middle part, and (4) closing of outflow openings in embankments and the inlet into the diversion channel (Figure 9). 1145