Modelling constructed wetlands: Scopes and aims - a comparative review

During the last two decades a couple of models were developed for constructed wetlands with differing purposes. Meanwhile the usage of this kind of tool is generally accepted, but the misuse of the models still confirms the skepticism. Generally some groups of models can be distinguished: on one hand mechanistic models try to display the complex and diffuse interaction of occurring processes, on the other hand the same kind of models are used to investigate single processes. New kinds of 'simplified' approaches - well appreciated by engineers - try to display system performances without going to deep into details. All types of models are valuable - some more for scientific usage, others more for engineering. The given summary tries to support potential users in taking the right choice in model selection. Big differences can be found in the model availabilities. Whereas some of the compared software packages are purchasable without limitation, some others are only accessible on their platform level, and some can be seen as exclusive property. From the experience of the authors it can be summarized, that research groups starting modelling/simulation studies should be encouraged to use the given knowledge before starting from scratch again.