Problems and Requirement for Additional Scientific Research

The examples illustrate the use of virtual aquifers to investigate exploration, monitoring and remediation strategies for contaminated aquifer systems. However, there is a large necessity for further investigation in the following areas  

The simulation of natural attenuation processes requires additional parameters for microbial degradation. Such data have been published in the literature but since different approaches exist to simulate biodegradation these parameters are normally not transferable to other models. Public use of numerical models to simulate natural attenuation would require compilation of a data set describing the size and range of microbial degradation constants and their dependencies on other parameters. 

As mentioned above such investigations have already been performed for some specific aquifer types from the outcrop analogue -project, other investigations are available in the literature (e.g. Borden, Cape Cod). Additionally existing data have to be systematically collected and compiled for different aquifer types. The extent to which data from existing geological investigations can be transferred to the virtual aquifer approach is not known, since they were not performed with this special aspect in mind. 

The generation of virtual aquifers requires statistical analysis of aquifer parameters. This has to be done for flow and transport parameters like hydraulic conductivity, porosity and dispersivity as well as for geochemical parameters like the content of dif- 

For interpolation of measured concentrations it would also be very helpful to test new regionalization and interpolation methods. Very often the Kriging Method is used, since it seems to produce realistic concentration distributions. With virtual aquifers, where the real concentrations are known, the quality of different interpolation methods for a spectrum of parameters can be tested. 

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