Aquifer Contamination at Roorkee/India Studied by Spatially Contrained Inversion of TEM Inloop Data

46 inloop soundings were carried out close to Roorkee/India on a contaminated area and on a noncontaminated site used for reference. Due to the inaccessibility of some parts of the survey area the TEM soundings could not be carried out on profiles and therefore were realized on an irregular measuring grid. First of all, the data were interpreted by a conventional 1D inversion and afterwards the TEM soundings were simultaneously inverted by a spatial constrained inversion to derive a quasi 3D conductivity model. The TEM-models show a relative low resistive aquifer (8-15 Ohm-m) at 5-15 m depth indicating a possible contamination which was also observed (radiomagnetotellurics, DC) and confirmed by other geophysical measurements on the same area. The other object of the study was the second deep aquifer at 40-70 m depth. Its resistivity was determined as 20-40 Ohm-m. However, the TEM inversion results couldn’t clearly indicate a possible contamination of this deep aquifer.