Landforms, which result from the interplay of physical, chemical, and biological processes acting on the surface, function as static boundary conditions for processes in geomorphology, hydrology, meteorology and other fields. The description, parameterization, and modeling of landform structure, as well as the terminology used, are fitted to the requirements of the disciplines and are, therefore, often strongly divergent. As a consequence, representations of landform structure for different disciplines are often not compatible and require frequent revisions and adaptations. Principles of the semantic approach to the problem are presented in this paper. The main objective is a semantically correct description of landform which is useful to all disciplines related to surface structure. The approach considers geometric form as a basic property, extended by topological considerations and semantic definitions. The potential, limitations, and open questions of the semantic-based approach are discussed using hillslopes as a case study. The focus of the paper is on semantic representation and only thereafter are the special features of DEMs, teals, and implementations considered. (C) 2001 Published by Elsevier Science Ltd.