One-Dimensional Hydrodynamic Modelling of River Floods with Infiltration

Abstract: The simulation of flood routing in open channels based on the Saint-Venant equations plays a considerable role in the forecast of runoff concentration and river floods. Yet, the traditional Saint-Venant equations do not incorporate infiltration loss and thus bear uncertainty if applied to scenarios with severe infiltration. Here a one-dimensional hydrodynamic model considering infiltration for open channel flows is established based upon the traditional Saint-Venant equations, with the soil infiltration described by the Green-Ampt equation. The governing equations are discretized by the finite volume method and the numerical fluxes are estimated by the total-variation-diminishing (TVD) version of the slope limiter centered (SLIC) scheme, which can automatically capture shock waves and discontinuities featured by hyperbolic equations. The proposed model is first validated against an experimental test case. Then the model is applied to investigate a real flood in the Zhuozhang River in Shanxi Province, China. The results obtained by the present model agree well with the field observed datasets, compared to those when infiltration is ignored. Sensitivity analyses of model parameters demonstrate that the discharge hydrographs are sensitive to Manning roughness and the parameters in the Green-Ampt equation. The proposed model incorporating infiltration is essential for river flood routing in arid and semi-arid areas in which infiltration is severe.

Keywords：Infiltration; Mathematical river modelling; Saint-Venant equations; Finite volume method; Flood routing forecast