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The method used for studying of horizontal changes in the sub-soil is _______
Resistive soundings
Resistive mapping
Mean resistivity
Critical distance
Resistive mapping
Resistivity mapping is an electrical geophysical method used to identify lateral (horizontal) variations in the electrical resistivity of sub-soil layers at a constant depth. By maintaining a constant electrode spacing while traversing across an area, it effectively maps variations in subsurface geological features or contaminants.
Resistivity mapping is an electrical geophysical method used to identify lateral (horizontal) variations in the electrical resistivity of sub-soil layers at a constant depth. By maintaining a constant electrode spacing while traversing across an area, it effectively maps variations in subsurface geological features or contaminants.
╧БaтАЛ=2╧АaR тАФ Apparent resistivity for Wenner array where a is spacing and R is measured resistance.
The method uses a fixed electrode array (such as Wenner or Schlumberger configuration) which is moved systematically across the ground surface along a profile. Since the electrode spacing is kept constant, the effective depth of investigation remains roughly uniform, allowing the survey to detect lateral changes in soil composition, such as buried structures, moisture content fluctuations, or geological boundaries.
Resistivity mapping is used for lateral reconnaissance of soil.
Constant electrode spacing ensures uniform depth of penetration.
Used extensively in site characterization to locate anomalies like sinkholes or boulders.
Distinguished from 'Resistivity Sounding' which focuses on vertical profile depth variations.
Efficient for large area reconnaissance
Non-destructive investigation method
Highly effective for detecting lateral geological discontinuities
Requires significant open space for electrode layout
Surface conditions and contact resistance can introduce errors
Limited depth discrimination compared to vertical soundings
Detecting localized soil variations for foundation planning
Mapping archaeological sites
Locating zones of groundwater contamination
| Feature | Resistive Sounding | Resistive Mapping |
|---|---|---|
Primary Objective | Vertical variations | Horizontal variations |
Resistivity soundings (Option A) involve changing the electrode spacing to detect variations with depth.
Resistive mapping is sometimes referred to as 'Electrical Lateral Profiling'.
B is correct тАФ Resistive mapping is specifically employed for evaluating lateral changes in the sub-soil at a fixed exploration depth.
Always remember: Mapping = Horizontal (Lateral), Sounding = Vertical (Depth). This mnemonic prevents confusion between the two primary electrical resistivity techniques.