Geophysics facilities on land

The facilities for geophysics on land involve non-destructive, in-situ measuring and monitoring techniques. These techniques use contrasts in the physical properties of the subsoil. The contrasts measured show differences in lithology, hydrology, composition and density as well as man-made constructions and infrastructure.

Deltares measuring facilities

In house we have techniques for characterising the subsoil and for localising specific properties. A number of techniques are also suitable for monitoring processes over time.
We have facilities for measuring seismics (MASW, VSP, tomography, reflection and refraction), geo-electrics (resistivity, including tomography, IP and SP) and electromagnetic fields. Other geophysical facilities are well logging, ground radar, optical fibre (continuous measurement of for example the temperature over large distances), sensors for in-situ measuring and remote sensing data processing. All measurements can be positioned accurately to the nearest centimetre using our precision GPS system.

Selecting and integrating techniques

In addition to using our in-house measuring equipment, we work closely with other parties and develop custom work. The starting point for every requirement is to examine what combination of techniques and knowledge could yield the best results for the project. This requires creative solutions sometimes, so that for a particular project a technique may be adapted, devised, rented or bought. Field observations and geological and hydrological knowledge always play a key role, and by integrating all measurements, observations and knowledge we deliver tailor-made solutions.

Applications and solutions

Techniques are applied for government and semi-government parties, research institutes, contractors, and project developers and consultancies involved in mineral extraction and water collection. Requirements can be divided into four categories.

• Surveying - We determine and survey the structure of the subsoil (geology), local geotechnical properties; stratum thicknesses and stratum transitions; channels and the fresh/saline interface.
• Interpretation support - Geophysical techniques are often used to link point observations and to put them in a 2D, 3D or 4D context. This makes the spatial interpretation of the point observations (drilling/probing, water samples, heights of gradients, etc.) possible or more reliable.
• Tracing and localising - We use these techniques to find breaks, hollows, leaks, springs and natural and artificial obstructions in the subsoil.
• Design and construction - In construction projects, a preliminary geophysical investigation can help in preparing a design that will minimise any risks. Examples are the installation of thermal storage systems and soil decontamination, as well as the construction  of  large structures such as wind turbines and industry.