Natural protected areas (NPAs) in Turkey are generally determined on standard topographic maps at a scale of 1/25 000, as opposed to cadastral border detection measurements. This situation generates a variety of problems with land management issues where the borders overlap an NPA region, as all NPA-related verbal and spatial data must be produced according to certain standards. Moreover, land management policies should be developed in relation to sustainable use and management of these areas. In line with this aim, the necessity for a protected area management system has emerged in which all spatial and verbal data are stored and can be used when needed. Before the creation of such a system, it is necessary to design a geographic information system (GIS)-based data model. This study examined the current situation of NPA site borders in a selected area using spatial data. It was revealed that the current system has no specific standards, the process is not being carried out systematically and the applied technical and legal criteria are not being properly followed. Therefore, the necessity has arisen for a data model design that contains all the necessary data in order to identify site boundary requirements. The data model design was generated using object-oriented Unified Modelling Language diagrams. Care was taken to ensure that the developed model was in compliance with the European Union-defined data standards (INSPIRE) and that it was implemented according to the environmental policy and standards set by the Land Administration Domain Model.