Transient Electromagnetic (TEM) Technology In Kenya
Grekkon Limited commercially pioneered Transient Electromagnetic (TEM) Technology in Kenya for use in hydrogeological and mineralogical surveys. It addresses a key challenge in he country; low borehole drilling success rate, currently at 60%. This means that for every 10 drilled wells, 4 will be ‘dry’. TEM increases this rate to >90%. TEM is used by institutions such as the government, NGOs/ CBOs, research organisations, and learning institutions. Other users are borehole drilling companies, large-scale miners, consultant hydrogeologists, and mineralogists
TEM profiler in use somewhere in Taita Taveta county by the Grekkon Limited technical team, and hydrogeologists from the Regional Centre for Ground Water mapping (RCGWM). This TEM version is ideal for shallow water surveys (less than 120M bgl). Note the electric pulse transmitter in the foreground, the yellow CPU unit in the middle, and the receptor in the background
What is TEM?
TEM is a modern, advanced geophysical imaging, non-intrusive technology that delivers fast, accurate, deep, and highly detailed subsurface models
How Does TEM Work?
How TEM works
Transient Electromagnetic (TEM) Technology In Kenya: Applications
- Hydrogeological surveys: TEM is used to map shallow and deep groundwater resources, identify potential borehole sites, and assess aquifer vulnerability. For example, in the Kakuma refugee camp area, TEM surveys were used to map groundwater hydrology and identify potential locations for new wells.
- Geothermal exploration: In regions like the Kenya Rift Valley, TEM (often in conjunction with Magnetotellurics) is used to map the subsurface resistivity structure to identify potential geothermal reservoirs and fluid-filled fractures.
- Mineral exploration: TEM can assist in identifying the location of conductive mineral bodies.
- Environmental surveys: The technology can be used to map geological structures near waste sites, helping with environmental impact assessments and risk analysis. It can also help delineate clay mineral deposits, sand, and gravel.
Benefits
- Non-invasive: The method does not require extensive groundwork or physical contact with the ground via electrodes, which is advantageous in difficult terrain.
- Efficient: It can map large areas quickly, using either stationary or towed-TEM methods.
- Inductive: It is particularly effective in areas with very dry or resistive top layers where traditional resistivity methods may struggle to achieve good electrical contact.
- Insight into subsurface layers: It provides a picture of the different layers of soil and rock beneath the surface
TEM equipment is light, making it easy to carry on site. It is easy to assemble, and disassemble in the field, allowing movement in tight spaces
Why Use Transient Elecromagnetic (TEM) Technology in Kenya?
Transient electromagnetic (TEM) technology in Kenya is superior to existing Vertical Electrical Sounding (VES) and Electrical Resistivity Tomography (ERT) technologies commonly in use today for the following reasons
- It’s accuracy level is >90%, hence hardly any “dry” boreholes
- It performs surveys three to five times faster, which makes it the ideal technology to map out large areas
- Has minimal field setup because it is non-invasive; no electrodes have to be inserted into the ground like VES and ERT
- TEM data provides an estimate of the water. Freshwater vs saline aquifers. It identifies zones of water contamination
- TEM determines aquifer recharge pathways so that ground-water is extracted from sources that provide long-term flows
A 3D ground model developed via mathematical inversion after a TEM survey
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