Pictures of flood catastrophes, mudflows or landslides regularly remind us that living space and danger areas are increasingly overlapping. In a first impulse, there is often a call for more and more technical safety measures. However, in order to separate living spaces and danger areas in an effective way, preventive planning is indispensable. Since the creative scope of spatial planning for already covered building land is limited, statu-tory provisions of the spatial planning laws focus on undeveloped building land. This diploma thesis deals with the overlapping areas of undeveloped building land and danger areas in Lower Austria, of which there are countless, experts say. According to the plan-ning law in Lower Austria, these areas have to be non-refundably redesignated if they can not be secured within a fixed deadline. The present work shows the legal regulations (legal analysis) and the practical implementation (interviews and analysis of technical information) according to these areas based on selected municipalities in Lower Austria. Afterwards, the resulting challenges are summarized and concluding recommendations in dealing with the problem in question are given.