The results of the numerical simulations of the dynamics of shallow waters for Volga-Akhtuba Floodplain are discussed. The mathematical model is based on the system of Saint-Venant equations. Numerical solution applies a combined LagrangianEulerian (cSPH-TVD) algorithm. We have investigated the features of the spring flood in 2011 and found the inapplicability of the hydrodynamical model with the constant roughness coefficient . We have found a good agreement between the results of numerical simulations and the observational data at gauging stations which allows us to estimate in low water min = 0.02 and the maximum water level in the river Volga max = 0.06-0.07.