Reconstruction of debris flow in the Gerkhozhan-Su river valley based on the chain modeling

The paper presents the reconstruction of the most catastrophic debris flows in the Gerkhozhan-Su river valley (North Caucasus, Russia) based on a chain of mathematical models. Transport-shift model was applied for 6 sections of debris flow formation or intense material increment, while for the rest the FLO-2D hydrodynamic model was used. A number of numerical experiments were carried out in the transport-shift model for a section of a debris flow origination site with a change in the parameters of a potential debris flow-forming soils, such as initial moisture content and density. According to the simulation results, with a rise in moisture content, the maximum debris flow discharge can increase by about 2.8 times. Modeling of debris flow in the Gerkhozhan-Su river valley was conducted for the case of low density debris flow. Based on the results, debris flow wave hydrographs were obtained at 12 sections. The results of modeling are in general agreement with the commonly accepted reconstructed pattern of the debris flow in 2000 and values obtained by videomaterials.