Modelling of the groundwater salinization in the coastal aquifers of Lower Saxony derived by airborne electromagnetics

摘要

The Federal Institute for Geosciences and Natural Resources (BGR) conducted large-scale airborne geophysical surveys (about 5900 km(2)) at the North Sea coast of Lower Saxony in the years 2000-2014. Airborne electromagnetics provided information about electrically conductive structures in the subsurface and enabled the discrimination between saline and fresh water, as well as between clays and sands. The State Authority for Mining, Energy and Geology (LBEG) and the Leibniz Institute for Applied Geophysics (LIAG) used these data to map the depth of the fresh-saline groundwater interface. As one result, a detailed groundwater salinization map of the coastal aquifers of Lower Saxony was produced at a scale of 1:50,000. This map shows the current state of groundwater salinization as provided by resistivity models derived from airborne electromagnetic data. Such models also served as baseline data for a hydraulic modelling of the freshwater lenses of the North Sea island of Borkum, and the fresh-saline groundwater interface at the coastal aquifer of Lower Saxony. Subsequent simulations show the development of the groundwater situation until the year 2100.