The objective of this application is the development of a particle-based cross-scale model for the simulation of flow and transport in unsaturated fractures and adjacent porous matrix The description of flow and transport processes in unsaturated fractured-porous media still poses great challenges to science, but is of great importance in many application areas such asB. in connection with the quantification of infiltration by mighty unsaturated rock materials (repository research), with the prognosis of groundwater recharge by fractured solid rocks and aquifer vulnerability. Flow and transport processes in unsaturated fissured aquifers are often dominated by their heterogeneous geometry and high contrasts in hydraulic properties. Due to the complex interplay of gravitational, inertial, capillary, surface tension, wetting dynamics and the highly variable gap geometry, it is often difficult to predict flows in unsaturated fractures.laboratory experiments and numerical models are one of the few possibilities to capture the highly nonlinear flow processes and the effect of interaction at complex multiphase interfaces within the fractures. Especially strong deformations of the interfaces can only be implemented with great effort with grid-based models. However, particle-based methods offer a simpler method for simulation. Free surfaces and phase boundaries move with the particles, so that no complex front-tracking algorithms are necessary. The fracture-matrix interface thus forms an essential interface between the porous matrix, which acts as main storage, and the fractures, which form the dominant hydraulic connection through the unsaturated zone. In order to be able to simulate the link between these two components at the process level, cross-scale model approaches are necessary and a cross-scale Smoothed Particle Hydrodynamics Model is to be developed as part of the project proposed here. The unsaturated flow and transport within the porous matrix is to be mapped by classical approaches (Richards) and coupled with the highly dynamic flow and transport processes (e.g. adsorbed films, drops, trickles) on the fracture surfaces. The model is integrated into a single numerical framework, simplifying coupling methods and avoiding different solution algorithms. The model is validated by numerical and laboratory experiments and used to describe effects of complex unsaturated fracture flow on humidification and transport dynamics at the fracture-matrix interface quantitatively and physically based.