Engineering geophysical investigations using electrical resistivity tomography for groundwater exploration in the Bodaibo district of the Irkutsk region

Abstract

Relevance. The need in technical groundwater exploration to construct a groundwater well for water supply of the rotation village of the mining and processing plant "Svetlovsky" in the Bodaibo district of the Irkutsk region. The electrical resistivity tomography is a common method for studying the upper part of a cross section and is widely used in mineral prospecting, geological mapping, engineering surveys, hydrological and environmental studies. The application of electrical resistivity tomography in these conditions will allow substantiating the location of hydrogeological wells and boreholes. Aim. Assessment of the geological and hydrogeological conditions of the area of work for the prospect of extracting groundwater for technical water supply for the needs of the rotational camp. Objects. Bedrocks, which are characterized by high resistance values and are aquicludes; permeable low-resistance zones that are water-bearing rocks. Methods. Ground-based geophysical surveys using electrical resistivity tomography; two-dimensional inversion of ERT data and their interpretation taking into account engineering and geological data of drilling and the GIS complex. As a result of the engineering and hydrogeological surveys performed using ground-based geophysical surveys by electrical resistivity tomography, it was established that the aquifer system of fissured rocks of the Imnyakh suite of the Proterozoic sediment complex (PR2-3im) is represented by fissured limestones of various colours from grey to blueish, with bands of mica schist. Analysis of the study results showed that the thickness of the exposed sediments is up to 50 m, the groundwater level of the operating horizon is opened at depths from 21 to 28 m. They are covered with a complex of low-permeability sediments of thickness from 5 to 11 m that are presented by interbedding of dense grey limestones and black metasandstones.