A NEW APPROACH FOR EVALUATING GEOLOGICAL HETEROGENEITY IN AREAS COVERED WITH CLAY TILL USING “THE POLY MORPHOLOGICAL CONCEPT”

A new approach for evaluating uncertainty in conceptual geological models in areas covered with clay till named The “Poly Morphological Concept” has been developed in Denmark. The concept attempts to include multidisciplinary GIS-tools, especially high-resolution elevation models, geological maps, well-data, geophysical data and expert knowledge on glacial geology for the compilation of the various data sources into a so called “poly morphological map (PM-map)”. The new type of maps include not only the traditional geomorphology of the upper part in a glacial landscape, but also buried/superimposed landforms in deeper parts of the aquitards, that likely influence the spatial distribution of fractures/sand lenses in the overlying till beds. The map may be combined with additional map-themes from the GIS database such as geological maps and clay till thickness, which may facilitate the formation of smaller polygons representing conceptual geological models with expected unique geological/hydraulic characteristics. The PM-concept provide a good first approximation of risk assessment for use of pesticides on regional scale (100m x 100m) or as a strategic tool for site evaluation of contaminated sites covered with clay till on more local scale. The PM-map may furthermore be used as a new representation of geological variability in numerical models attempting to better capture the important aspects of the flow domain structures in areas covered with especially clay till.