3d Groundwater Mapping in Denmark Based on Calibrated High-resolution Airborne Geophysical Data

Denmark occupies a total area of some 43,000 km. Most of the c ountry consists of Quaternary deposits overlying Cretaceous chalk, limestone, and Tertiary sand and clay. The topography is low-lying, reaching a maximum of 172 m above sea level. The combination of lo w topography and widespread, consolidated, and unco nsolidated aquifers ensures a plentiful and easily accessible water resource. Groundwater recharge averages 100 mm per year, but can vary in the ra nge of 5 0–350 mm. Curren tly, approx. 800 10 -6 m of water is abst racted annually. Household consumption by the 5.35 million inhabitants amounts to approx. 250 10 m per year. Of this amount, 99.9 % derives from groundwater. Groundwater quality in Denmark is generally good, which obviates the need for complex and expensive water purification. Moreover, the Danish water supply is decentralized, which renders expensive, lengthy pipelines serviced by large, central water plants unnecessary. The drinking water is not chlorinated and is of bottle water quality at the ta p. Altogether, there are around 2,900 public water supplies. Two thirds of the water abstracted for the natio nal water supply derives from 200 mu nicipal waterworks and one third from private cooperative waterworks.