Diachronic study of free aquifers using the method of electric tomography: a case study in northern Greece

摘要

Electric tomographies were employed at a site in Northern Greece in order to study the ability of the method to detect seasonal changes of the water-table level and changes of the quality of the ground water. The selected location is threatened by contaminants that infiltrate the aquifer (dump leakage). Seasonal variation of the concentration of the pollutants is expected to affect the conductivity of the aquifer. Therefore, repeated tomographies can be used for the detection of pollution. Water-table level and conductivity measurements in a borehole and a stream nearby were also used in this study. The measurements were repeated approximately every three weeks and changes of the water-table were associated with changes of the 2D inverted tomographies. At the same time changes of the conductivity of the aquifer are associated with the water quality of the aquifer. The results show that geoelectric tomography detects seasonal variations of the ceiling of the transition zone form the dry to the saturated alluvial deposits. Moreover, we detected changes of the proportion of the pollutants in the stream water during the summer, due to decreased precipitation.