Hydrological modelling with components: A GIS-based open-source framework

This paper describes the structure of JGrass-NewAge: a system for hydrological forecasting and modelling of water resources at the basin scale. It has been designed and implemented to emphasize the comparison of modelling solutions and reproduce hydrological modelling results in a straightforward manner. It is composed of two parts: (i) the data and result visualization system, based on the Geographic Information System uDig and (ii) the component-based modelling system, built on top of the Object Modelling System v3. Modelling components can be selected, adapted, and connected according to the needs of the modeller and then executed within the uDig spatial toolbox. Hence, the system provides an ideal and modern integration of models and GIS without invalidating existing solutions. Compared to traditional hydrological models, which are built upon monolithic code, JGrass-NewAge allows for multiple modelling solutions for the same physical process, provided they share similar input and output constraints. Modelling components are connected by means of a concise scripting language. Furthermore, the system utilizes the Pfafstetter numbering scheme to represent the digital watershed model; the adaption of this topological classification of a basin with respect to NewAge is explained in this paper. Finally, the system application for the Fort Cobb watershed and its results are presented.