The numerical simulation of granular material flows presents significant challenges due to large strain regimes and complex material behavior. Accurate simulation of granular flow dynamics and boundary conditions is essential for developing predictive simulation systems for natural hazards. Within the Material Point Method (MPM) framework, two complementary approaches are presented. The first employs solid dynamics formulations solving large deformation equations with both irreducible and mixed formulations incorporating Mohr-Coulomb failure criteria, stabilized through variational multiscale techniques. The second approach adopts fluid dynamics-based formulations, developed in both velocity-based and displacement-based variants, to capture the flow-like behavior of granular masses. Particular emphasis is placed on evaluating the dynamic actions resulting from granular flow impacts on both rigid and deformable structures, crucial for the design of effective protection systems. Partitioned coupling strategies between MPM and other methods (FEM, DEM) further enhance the capability to simulate complex structure-flow interactions in the context of natural hazards such as landslides, debris flows, and mud flows. All algorithms are implemented within the open-source Kratos-Multiphysics framework, enabling high-fidelity modeling of these phenomena and their interaction with structural elements.