Application of electromagnetic reflection method (EMR) to investigate confined and perched aquifers

There are many reasons to drill a hole, for example test borings for local geological sampling, groundwater monitoring or shotpoint drilling for seismic investigation. Previous knowledge about areas endangered by artesian water is important to avoid drilling in these areas. Undesired artesian water outflow can be dangerous and causes a lot of damages. Perched and confined aquifers are common in areas of push moraines due to the interlocking of glacial sand, till and boulder clay. The groundwater levels change abruptly in steps because of steeply dipping thin layers with low perrneability between the sand layers ofthe aquifers. Owing to the differences of the electrical properties (dielectric constants and conductivity) between soils or rocks and water, electromagnetic energy is reflected at boundaries of material with different water content, since the water changes the relative permittivity of most soils or rocks by a factor 5-6. This fact makes the groundwater table a good reflector of electromagnetic energy if it is associated with a steep change in the soil's water content. The aim of the present paper is to demonstrate the possibility of using electromagnetic reflection method (EMR) to detect some groundwater table anomalies (mainly steps or a discontinuity) and its interpretation combined with the known geological and hydrogeological information to predict artesian waterand perched aquifers.