Assessment of the ice jam potential on regulated rivers and reservoirs with the use of numerical model results

Abstract

This study presents an attempt at estimating the jam potential on rivers with significant anthropogenic intervention in the course or flow characteristics of the river. The DynaRiCE model was used for forecasting both the place and time of an ice jam occurrence. In this modified method, two ice parameters are subjected to analysis, namely the relative ice-to-water velocity (vivw),and the ice thickness to single floe thickness (ηiη0). Both variables were analyzed at two locations; first spot is the Odra River near Słubice-Frankfurt bridge (between 581 and 586 km), and the second is the Vistula section between the existing Włocławek dam (674.75 river km) and the planned Siarzewo dam (706.38 river km), covering a 31.6 km reach. Once the model is implemented in the selected areas, the numerical simulations were processed and the obtained results were analyzed in terms of ice accumulation and jamming. The results on both rivers shown some potential of ice jamming, due to the planned engineering works. In the case of the Odra river, it was indicated that ice jam potential increased during the ice run of high concentration in the average flow conditions. For the Vistula river two locations for ice jamming were designated and for both of the points an increase of the ice thickness by about 60% from the initial, single flow thickness was observed. Also in this case, the area-averaged ice velocity in an initially specified location drops below 15% of the average water velocity in that area. According to the used methodology, both cases are classified as ‘ice jam probable’ type.