Landslides and avalanches have the potential to trigger devastating flood waves as debris or land mass impacts the fluid surface of a reservoir. FLOW-3D offers various degrees of sophistication when it comes to modeling both the avalanche itself and the resulting flood wave propagation. The Moving Objects Model allows for slabs of earth to slide in a rigid body fashion as solid objects over topography. The granular flow model allows for a much more detailed simulation of the avalanche process. In both cases, the impact and sub-aerial propagation of the mass, with the associated flood wave is resolved. Landslides do not only occur over bodies of water, in the case of tailings for instance, customized constitutive relations are easily implemented using FLOW-3D‘s non-Newtonian fluid model.