Surface and borehole geophysical methods are used in hydrogeological investigations for mapping and monitoring the physical property changes of the soils and water bearing rocks. Main applications include bedrock topography, structural profiling, water table depth estimation, delineation of fracture systems, estimation of permeability, water content and porosity of the aquifers, mapping salt water-fresh water boundaries and migration pathways delineation.
Geophysical results are indispensable for planning detailed groundwater investigations and aquifer management and more importantly when targeting areas for drilling water supply wells in rural communities where services of potable water are not available. Surface and borehole geophysical methods include Seismic Refraction, Electromagnetic Conductivity Profiling, Vertical Electrical Sounding, 2D Resistivity Imaging, Magnetic and Self-Potential. Borehole geophysical methods include Borehole Resistivity and Fluid Conductivity Sounding.
ERT - VES
Lake and River Bottom Profiling
Detailed maps and profiles of the lake and river bottom can be produced with the implementation of Ground Penetrating Radar mapping techniques over frozen waters or by deploying the scanning systems on board of boats or platforms. The interpretation of the GPR results are valuable for characterizing the water column properties, the type and thickness of the bottom sediments.
Porosity, Water Content and Depth To Water Table
Estimation of the water table depth is important for drilling activities, environmental investigations, and hydro-geological and geological studies. VES, Electrical profiling, EM and Seismics methods are used to identify the depth to the water table.
Water Well Location
Groundwater investigations using geophysical methods will be time-efficient covering larger areas at low cost. Geophysical exploration is used to find the best locations for drilling water wells for communities and villages where utilities are not implemented. The quality of the water and various parameters such as transmissivity, porosity and permeability of the bearing aquifers are estimated using surface and borehole techniques such as Vertical Electrical Sounding, Electrical Profiling, Electromagnetics, Nuclear Resonance Sounding, Electrical Resistivity Tomography and Seismics.
Salt Water Intrusion Mapping
Saltwater intrusion in fresh aquifers is a serious concern for many communities in coastal areas where fresh water is highly priced for personal consumption, irrigation, industrial processes and other daily uses. The dissolution and increase of the salt content in groundwater will reduce the resistivity of the soils and water bearing rocks to the level where the limits of the intrusion can be easily map by using surface geophysical instrumentation. Electrical Resistivity Tomography and Transient Electromagnetic methods are commonly used for mapping salt intrusion.