This paper focuses on the description of a specific formalism for geographic database design and a complementary language for the expression of topological constraints. The proposed formalism enables designers to easily and clearly specify aspects related to geographic information. For that, our proposition uses concepts that are easy to understand for GIS (Geographic Information System) designers. Indeed, the main goal of our works is to respond to the needs of geographic database designers in offering a formalism more adapted to the field of GIS than classical modelling languages. Moreover, we also address the problem of precisely express topological constraints in complement of the geographic object description.