New techniques in hydrogeophysics for the evaluation of sedimentary aquifers

Motivation and aims

Natural aquifers are the most important source for drinking water. They are of rising importance due to the increasing limitations of reservoirs. To protect them from pollution and to use them sustainably is of urgent importance. Respective regulations (WHG1, WRRL2) demand our responsibility.

To quantify parameters like dimension, vulnerability and capacity of an aquifer is a recent topic worldwide. In Germany the Federal Water Act in particular demands, that the water supply should be preferably satisfied from close by resources. But near surface aquifers are often polluted by diffuse sources, which are often agricultural. The contamination with nitrate is a special focus in this regard. To shift the production to deeper aquifers just delays the problem.

Keeping these tasks in mind, the lack of detailed knowledge of hydrological storage and transport parameters, like effective porosity and hydraulic conductivity/permeability, as well as the quality of the groundwater are often disappointing. Boreholes can give highly resolved information about these properties at one location. But due to economic or logistical reasons, they often cannot be applied in an appropriate amount to give the spatial resolution necessary to understand the complex hydrological processes in the subsurface. The recent developments in hydrogeophysics try to close this gap by using innovative and non-invasive approaches.

The Leibniz Institute for Applied Geophysics meets this demand by establishing the working group ‘New techniques in hydrogeophysics’. With further developments and the linking of promising methods a considerable progress to determine the controlling hydraulic parameters is expected.

The main aims of the working group are:

• to improve the determination of hydraulic parameters like porosity, hydraulic conductivity as well as storage and extraction properties from geophysical measurements,
• to apply these new methods successfully in the field,
• to merge the information from different methods and to develop an integrative measuring and interpretation procedure, and
• to validate the thus achieved improvement of hydraulic models at test sites.

Main targets of the studies are sedimentary aquifers. To use them sustainably a good knowledge of the hydrological properties is necessary. Sub-goals for the projects are:

• the development of the methods for their application to natural aquifers,
• to link the different methods to their complementary application, processing and interpretation (joint inversion),
• to validate the hydraulic models gained from the complementary approach by comparing it to conventionally achieved results.