PUMPING TESTS AND HYDROGEOLOGICAL INVESTIGATIONS OF AN ARTESIAN AQUIFER NEAR HORSENS, DENMARK

Abstract

In the Egebjerg area, near Horsens, several aquifers consisting of glacial outwash material deposited in a glacial eroded buried valley in the Tertiary formation have been encountered. The lowest of these, which is the main productive aquifer, and which has leaky artesian conditions, has been investigated. The thickness of this aquifer varies from 10-40 m. The lower confining bed consists of boulder clay or meltwater clay underlain by boulder clay. The upper confining bed, where leakage occurs, consists of meltwater clay with thickness from 0 to 5 m. The upper meltwater deposits include a sequence of interglacial lake deposits and several layers or laminae of clay, which separate this water-bearing material into more aquifers with watertable or artesian conditions. In the eastern part of the area boulder clay deposits are found at the top of the sequence. The Theis modified non-equilibrium equation and its derived formula for the non-steady-state leaky artesian case have been used to determine aquifer properties from pumping test data. By means of Jacob's method and a logarithmic method, well characteristics are determined graphically. Barometric efficiency, reverse fluctuations, and boundary conditions are recorded and discussed.