Hidrológiai Közlöny, 2017 (97. évfolyam)
2017 / 3. szám - MANAGING ENVIRONMENTAL RISKS - FLOOD PROTECTION EXPERIENCES AND COOPERATION IN THE DANUBE RIVER BASIN - Engi Zsuzsanna: Flood hazard modelling of the River Mura based on the silting up processes of the inundation area
Zsuzsanna Engi: Flood hazard modelling of the River Mura based on the silting up processes of the inundation area 91 Hydraulic modelling - Simulation of the silting up process in the inundation area For the purpose of modelling the silting up process in the inundation area of the river Mura, the modelling systems MIKE 11 ST- Graded ST and MIKE 2D FM ST were used. 1D model was used to support the decision making to further develop the 2D model. In the sediment transport modelling process, the Van Rijn (van Rijn 1984a, 1984b, 1984c) and Engelund-Hansen (Engelund and Hansen 1967) equations were used (Table 2). The results of erosion and the silting up process were underestimated with the sediment transport method of Van Rijn (Figure 11). Table 2. Data about model development Transport formula d50 Start time step, Time step factor Start time step Morphology Start time step v2_0 Van Rijn 2 mm Smagorinsky HD non equlibrium T: 1440 st,30 helical flow 2860 no bed erosion 1440 v6_0 Engelund- Hansen 2 mm SmagorinskyHD non equlibrium T: 1440 st,30 helical flow 1440 no bed erosion 1440 v3_0 Engelund- Hansen 6 mm Smagorinsky HD non equlibrium T: 1440 st,30 helical flow 1440 no bed erosion 1440 v8_0 Van Rijn 6 mm SmagorinskyHD non equlibrium T: 1440 st,30 helical flow 1440 no bed erosion 1440 Figure 11. Erosion (m) or the silting up (m) process during the simulation of bed level geometry change in versions v3_0 (EngelundHansen) and v8_0 (Van Rijn) The transport method of Engelund-Hansen yielded erosion and silting up of the bed level was »beyond possi- more realistic values, but in some locations the forecasted bility« (Figure 12). Figure 12. Morphological changes of the experimental area 2 2nd 6th day 8 th day day 4th day Bed level change [m] I I Above 0.80 0.60- 0.80 IS 0.50- 0.60 ■B 0.40- 0.50 I I 0.30- 0.40 0.20- 0.30 0.15- 0.20 0.10 - 0.15 0.05- 0.10 0.02- 0.05 0 .00- 0.02 -0.02- 0.00 -0.05 - -0.02 ■ -0.10- -0.05 ■-0.50--0.10 Below -0.50
