Example of a DUAL induction gamma log in a liner, showing time series on a land reclamation area in the sea: monitoring of refreshing of saline groundwater due to infiltrating rain water.

The borehole logging sensor measures resisitivty at two different exploration depth's in combination with natural gamma. This can distinct clay (or artificial clay seals) from sand with brakish or saline water.

Comparison of DUAL induction gamma log (in a plastic liner) with normal logging in an open hole. Dutch dune area. Testing Bentonite seals

The instrumentation in use is suitable for remote, vulnerable or hard to reach area's.

Underwater resisitivity measurements with marine floating and underwater cables. Detecting of a fracture system in lake Pateira, Fermentelos, Portugal.

Forward models and real measure- ment in a peatland area. With forward models the detectabilty of a target was tested and afterwards compared with the real data. Blue colors indicate clay and yellow saturated sand with fresh water.

Mapping of a landfill leachate plume . Blue color is indicates the leachate that moves away form the landfill. (Figure with permission of

Boris van Breukelen, TU Delft).

Detection of burried ice pushed ridges influencing ground water flow. Blue colors indicate "pushed"  and pleated clay layers blocking the groundwater flow.

TDEM in a agricultural field. TDEM measurements generate  relative deep resistivity data,  with limited disturbance at the surface, 1D, relatieve low resolution, less senstive for high resisistivity and not suitible in urbanized area's

Fresh water intrusion from lake IJsselmeer into a saline polder, comparison of ERT with TDEM. The light blue color  is the fresh groundwater. Red color indicates saline groundwater.

Groundwater exploration in Kenya, prospecting with TDEM and ERT to locate fracture's  and paleo valey's. Red color (lower figure) is indcating bedrock, yellow the paleao valley and green indicates the actual fracure. The exploration depth of TDEM is much larger than ERT, inidcating a deep fracture or buried gap. The resulting borehole were high yielded

Exploring deep sand layers for the location of a new wellfield  for drinking water. Red color indicates sand with saline ground water, yellow fine - medium course sand and brown course sand with fresh groundwater.

FDEM DUALEM, this instrument uses a fixed frequency, has 6 receivers and generates automatic data aquisition, while moving, for 2D (and 3D) profiles up to 6 mtr

DUALEM profile along dykes to locate gully's, comparison with standard CPT method. Yellow color indicates silt and fine sand. The gully's in this case are filled with peat and clay

2D and 3D interpretations. Detection of peat layers, blue color indicates peat.

2D and 3D interpetation of dyke stability. Brown color indicates old river gully's filled with sand crossing underneath the dyke. This might lead to leakage passing under the dyle body into the polder.

Results of the application of TDEM, ERT and AMT in Kaijado Kenya mapping paleo valley's and fracture zones for groundwater exploration.

3D mapping of saline groundwater upconing in a Dutch polder. A combination of  SKYTEM, ERT, DUALEM and Borehole logging.

Blue colors indicate fresh ground water, red colors saline groundwater.

(with permission of Artesia and Waternet)

Combination of shallow and deep methods to explore the best location for a new (public drinking water) wellfield

St Helena, hydrogeological mapping, DEM, satellite images, borehole logging, ERT, data analyses (still in progress).