Why 2D-Modelling of Transport and Reactions

However, users of these types of models will usually reach the limit of feasibility 

In case the modeller wants to include a multitude of (bio)geochemical processes - as in a natural aquatic system - it is indispensable to have first understood these processes quantitatively, in order to describe them afterwards according to the measured parameters. Prerequisites are extensive field measurements and/or laboratory experiments. It is absolutely essential to understand quite a few things about processes in complex aquatic systems and about model theory before running complex models for a coupled transport/reaction-modelling just like that . 

The second restriction results from the time of calculation of these models. It is not at all exceptional, that one-dimensional models with many parameters and for long modelling-times will need hours or even days - despite of fast computers - for one run of the programme. Skilful handling of the model might possibly avoid absurd calculations, and computer networks may speed up the time of calculation, however these models will always be restricted due to their time of calculation. 

In case of two-dimensional modelling, other forms of simplification are required, in order to handle the time of calculation. This study proceeds on the assumption that normally well-understandable processes, which are separately measured and separate- 

as a result of the drainage activities, a major part of the region lies below the river water table. The steep hydraulic gradient between the water table of the river Oder and the aquifer results in the permanent lateral infiltration of river water into the shallow upper aquifer which is confined along the river banks. The sands and gravel of 

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