Collection of abstracts 13th GAMM-Seminar Kiel on Numerical Treatment of Multi-Scale Problems January 24th to 26th, 1997.

Friday, January 24th, 1997

Geometric modelling of complicated hydrogeologic structures

A geometric simulator is presented, which is applicable within the framework of hydrogeologic modelling (groundwater flow and contaminant transport).

The data basis for the geometric analysis is obtained from geologic information (maps, vertical profiles, borehole logs). At first this data must be analyzed to construct a consistent geometric model. To this purpose geologic objects (e.g. boreholes, fractures, aquifers) must be identified as lines, surfaces and volumes. Next, topologic consistency must be obtained, that means surfaces and volumes must be compatible (no isolated areas, no penetrating surfaces). A number of tools are implemented in the interactive package DALI to manipulate the data, such as identification functions (boundary generation) and cutting planes, data generalization and mesh generation. The possibilities of the geometric simulator are demonstrated by a number of 2-D and 3-D examples of hydrogeologic systems.

The geometric model provides a first discretization for a numerical analysis. In general, the quality of the discretization must be improved for solving the coupled partial differential equations of flow and transport by use of the finite elment method. The probability of the geometric simulator and the mesh generator is illustrated by a study of a real aquifer system. The data for this investigation was kindly provided by the BGR in Hannover.