Evaluation of the possibility of searching for groundwater using electrical resistivity tomography based on the data of numerical modelling in complicated permafrost conditions (the case of the territory in the eastern part of the Republic of Buryatia)

Abstract

Relevance. Groundwater is the main source of industrial and technical water supply for mining facilities. The geological structure of the studied areas can be complicated by various factors that make it difficult to search for and localize groundwater. In this regard, electrical geophysical prospecting methods are often included in the complex of prospecting and exploration works, before which it is necessary to justify the application of the chosen method for solving the problems by performing numerical modelling. Aim. To substantiate the use of electrical resistivity tomography for the search for groundwater, taking into account complicating factors, including perennially frozen rocks, taliks, and fault zone, by numerical modelling. Objects. Geological environment represented by Quaternary system rocks and permafrost rocks of Cretaceous sediments of the Zazinskaya intermontane area, fault zone, talik zones. Methods. Solution of the direct problem, solution of the inverse problem, ground geophysical surveys using electrical resistivity tomography. Results. Based on the performed numerical modelling, it is shown that the use of electrical resistivity tomography is expedient when searching for groundwater in the area characterized by various factors: permafrost, talik, and a fault zone. Based on the results of solving direct and inverse problems of electrical survey, using field works performed in 2020 in the Eravninsky district of the Republic of Buryatia as an example, it is shown that pole-dipole arrays in electric resistivity survey with electrode distance of 5 m, successfully confirmed by drilling operations, allow us reliably delineate potential zones of water inflow. These zones, characterized by low values of electrical resistivity, in this area, are related to talik zones, which are powered by heat flow from the bowels of the earth.