The conditions of constructing new buildings are getting more and more complicated, particularly on the urban territoritories, commonly with the existing housing development, which may negatively affect it. "Point" high-rise buildings are constructed with high values of unit load onto the foundation. The reconstruction of existing buildings, most often with superstructure of 2 - 4 stories is becoming more extensive. Utilization of underground room of cities and construction of subsurface complexes of different functions, transportation tunnels and large-diameter collectors is intensely increasing as well. At the same time, a considerable part of the building territory is complicated by construction-unfavorable engineering-geological and environmental conditions, e.g. dangerous geological and engineering-geological processes: karst, landslide, erosion and flooding. These conditions are often deteriorated by negative man-made factors: dynamic impact, leakage from water-carrying communications, groundwater pumping-off, cutting slopes, etc...
At all stages of engineering and hydro-geological operations the electric survey methods are intended to fulfill the following assignments:
· Mapping loose sediments with the purpose to delineate the area of distribution, to determine thickness and lithologic composition;
· Exploration of the upper cross-section with determination of thickness and composition of some layers of loose sediments and depth of bedrock occurrence;
· Mapping tectonic units and assessment of fracturing and weathering of rocks;
· Searching for and delineating ancient valleys;
· Discovering and mapping karst zones, cavities of natural or technogenic origin;
· Landslide exploration;
· Evaluation of physical-mechanical properties of rocks in the natural occurrence;
· Evaluation of corrosion activity of ground and intensity of roaming electric currents;
· Permafrost studies;
· Prospecting and exploration of groundwater, determination of the level of occurrence and distribution.
Besides, the methods of electric survey can be employed for specialized targets: mining works, surveying pipeline corrosion and archaeological investigations.