## 4 Conclusions  
This research shows the results of the detailed field investigation, with a comparison of two numerical models of the Selanac debris flow. For comparison, different numerical approaches are chosen, one FVM-based (RAMMS DBF program) and the other a meshless method (SPH code). A field investigation was first made using geophysical methods considering how huge debris flows are. Then, a detailed DEM was made to compare two epoch DTMs; the RAMMS model was made continuously for a longer period, in different versions of the program, using different-quality DTMs [43]; the SPH code gives more possibilities in modeling, including different rheology laws. For comparison, here, we use the same constitutive, rheology model. The selected source area is the same, with the possibility to use different depths in SPH since the model is defined in points. For comparison, we used the same position of the profile as profile 5 for ERT investigation (about 20 m). The Voellmy rheological law was used to ensure the most accurate comparison among the results. The most suitable parameters for the Selanac model were 0.35 and 500 m/s\({}^{2}\), which provide the most realistic representation of material propagation. The validation was performed by comparing a single cross-section, as well as in the case of the RAMMS model, by comparing it with the ERT5 profile and the elevation difference model. Figure 11: Comparative view of final material depths at position of ERT 5 profile. The modeling was significantly more influenced by the prediction of the frictional parameter compared to the turbulence parameter. The final values of the deposited material depth were overestimated in the SPH program compared to the measurements conducted through ERT investigations. On the other hand, the RAMMS model shows a large amount of material flowing through the Selanac River (up to 2/3 of the total material). The differences in the estimated depth of material deposition and the calibrated parameters are linked to the different solution algorithms on which these two programs are based. The calibration of the turbulence parameter is the same for both flows, while there are differences in the calibration of the friction parameter for both flows. In the case of the Selanac model, the importance of modeling two phases in flows is observed. By using the two-phase SPH model, the deposited material is stopped in the deposition zone, unlike in the RAMMS model, where it was not possible to model the material to prevent it from flowing significantly beyond the deposition zone. These findings indicate that utilizing multiple simulation codes is essential for accurately predicting specific events, evaluating potential risks, and developing appropriate countermeasures. In the previous study [45; 46], various methods were applied to assess the susceptibility to instability in the Ljubovija municipality area. This resulted in susceptibility maps for instability occurrences and a comparison of the accuracy of the applied methods. The Selanac debris flow was activated in areas of mass flow occurrence following extreme rainfall in 2014. The potential for flow development in a broader area, based on defined potential initiation zones and using one of the susceptibility assessment methods, along with rheological parameters established for the Selanac debris flow, provides the possibility to estimate propagation in other potential areas. This could help prevent negative impacts in the future. Conceptualization, J.K.; methodology, J.K. and M.P. ; software, M.P. ; validation, J.K. and S.M.T. ; formal analysis, S.M.T. and M.S.-P.; investigation, J.K. and D.D. ; resources, T.D. ; data curation, J.K.; writing--original draft preparation, J.K.; writing--review and editing, J.K.; visualization, M.S.-P. and M.M. ; supervision, M.P. and B.A. ; project administration, B.A. ; funding acquisition, B.A. All authors have read and agreed to the published version of the manuscript.