Numerical model of shallow water dynamics in the channel of the Volga: estimation of roughness

The results for the numerical simulation of the dynamics of shallow waters for the Volga–Akhtuba floodplain are discussed. The mathematical model is based on the system of Saint-Venant equations. The numerical solution uses a combined Lagrangian–Eulerian (CSPH-TVD) algorithm. We investigated the characteristics of spring flood in 2011 and received the inapplicability of the hydrodynamical model with the constant roughness coefficient $n_M$. The agreement between the results of numerical simulations and the observations data at hydroposts allowed us to obtain estimates $n_M $ in low water $n_M^\mathrm{min}=0.02$ and the maximum water level in the channel of the Volga $n_M^\mathrm{max}=0.047$.