The standard applies to research of the soil up to a depth of 500 m, which is aimed at obtaining information about the lithological composition and/or groundwater quality. Note The geoelectric method is indirect. If the soil is homogeneous, the resis ivity of the soil can be measured. However, when it is anis tropic or inhomogeneous, an apparent resis ivity is measured, which is a non-linear weighted average of resis ances of the different layers. The measured resis ances provide information about lithological composition and groundwater quality (see Appendix B) and variations therein. If the lithological composition in a contaminated area does not change laterally, differences in measured apparent resis ivities can be attributed to differences in groundwater quality. Because the interpretation of geoelectrical measurements is not clear, it is recommended to use additional data in the form of drillings, soundings, borehole measurements, electromagnetic measurements (see NEN 5774) or groundwater analyzes in the interpretation. When sufficient additional data are available, a good quantitative interpretation is possible. The vertical structure of the subsurface at the location of the measurement can be derived from a (complete) geoelectrical measurement. Mainly lateral variations are derived from electromagnetic (or geoelectric) profile measurements (see NEN 5774).
NEN 5773-1990 history
1990NEN 5773-1990 Soil - Determination of resistivity using the electrical sounding method