A Numerical Hydrodynamic Model of a Long Segment of the Ural River and Its Application to Assessing the Inundation Risk of Residential Areas by Floods and Breakthrough Waves

A numerical hydrodynamic model was constructed for the segment of the Ural River from the Iriklinskoe Reservoir (inclusive) to a site 30 km downstream of the Sakmara River inflow; therefore, the total length of the model reach was >700 km. To reduce the time of model development and to accelerate the calibration and variant calculations, the segment was divided into three successive parts of the channel, interacting through consistent boundary conditions. The simulation is carried out with the use of a domestic high-accuracy software package STREAM 2D CUDA, taking into account abrupt changes in bottom elevation and multifractional soil composition. The model was calibrated for constant water discharges. Calculations were carried out for a spring flood with an exceedance probability of 1% and a breakthrough wave of the Iriklinskii Hydropower System under two scenarios. Maximal water levels, depths, and inundation zones were obtained. An effect of a many-time increase in the steepness of the leading front of the flood wave within the domain was revealed.