 At the time, it was common practice to rewrite a new model to fit the need of a new groundwater scenario.The concept for MODFLOW was originally designed in 1981 to provide a common "modular" groundwater model, which could be compiled on multiple platforms without major (or any) modification, and can read and write common formats.Different aspects of the groundwater system would be handled using the modules, similar to the idea of a "component stereo system".