|Format||GIS line and polygon data. (ESRI, MapInfo, others available by request.)|
30p per km2 for commercial use. Subject to number of users, licence fee and data preparation fee.
This theme provides information on the electrical resistivity of a geological material to be used where the earthing characteristics of the ground are required.
The spatial model covers England, Scotland and Wales at 1:50 000 scale using data from the following BGS datasets: Soil Parent Material Map, the National Geotechnical Property Database and the Geophysical Laboratories Database.
The resistivity of geological units is an important factor in engineering activities where the electrical characteristics of the ground are required, e.g. in earthing of electrical systems. The resistivity of the ground is dependent on a number of factors including pore water resistivity, saturation and the clay content of the underlying geology.
Electrical resistivity is an intrinsic property of a material that is measured as its resistance to current per unit length for a uniform cross section. The national attribution of resistivity is based on the calculation of resistivity using the methodology published in An effective medium algorithm for calculating water saturations at any salinity or frequency (Berg (2007)).
The BGS holds several thousand field resistivity soundings but they cover a limited number of geological units and are unlikely to cover the lithological variation and saturation conditions that may be encountered. Instead, the Berg method uses a number of parameters, which are known for the lithologies of many geological units or can be reasonably estimated using knowledge of similar materials (from the Soil Parent Material Map, the National Geotechnical Property Database and the Geophysical Laboratories Database) and the field soundings results as a guide.
Resistivity is of interest to a wide range of organisations concerned with development including infrastructure, utility companies, local authorities, green energy companies, developers and engineering consultants and contractors, and is particularly relevant to the major power distribution networks.
The Soil Parent Material Map of Great Britain, which describes the geology of the near surface, has been classified with modelled values of electrical resistivity. The description of the classification can be found in the free downloadable user guide.
Contact Digital Data for more information.