The object-oriented design of the integrated water modelling system MOHID

With increasing computer power, the modelling tools for water resources, nowadays, not only integrate physical-based transport models with biogeochemical process models, but also couple surface water body models, groundwater models and hydrographic basin models. This paper describes how the MOHID Water Modelling System achieves the mentioned integration using object-oriented programming in FORTRAN 95. After a short historical overview of MOHID's evolution, this paper focuses on the object-oriented design of the water modelling system MOHID and the way how object-oriented features are implemented in FORTRAN 95. Attention is also given to the way how the numerical software code interacts with the graphical user interface. It follows an exemplification of how the object-oriented design is useful for implementing complex system for two cases: the operational model of the Tagus Estuary and the coupling of the Trancao Basin model to the Tagus Estuary model.