Experience gained in North America, Japan and Europe has proven that flexible protection systems provide an ideal method of resisting dynamic loads such as those resulting from debris flows, due to their large deformation capacity and permeability to water. Similar to rockfall loads, the action of debris flows on a protection barrier is mainly dynamic. However, in contrast to falling rocks, debris flows do not impose a concentrated impact but a distributed load on the protection system. Therefore, structural adaptations of a typical rockfall protection system are unavoidable in order to achieve a reliable protection system against debris flows such as special rope guiding details, abrasion protection, etc. This report summarizes the results of a research project aimed at developing a dimensioning concept for flexible debris flow protection systems. The concept involves specially focused research combining laboratory tests, fully instrumented field installations and the corresponding numerical simulations. The report is intended to provide a basis for engineers or other specialists in the field of natural hazards to calculate and understand the design of flexible barriers against debris flows within channelized river beds.