Ecological and geophysical studies of buried erosional incisions in an industrial and urbanized area (using the example of the Milchanka River, Gomel, Belarus)

Abstract

Introduction: the work is devoted to the study of erosional incisions of small rivers in urban areas buried by technogenic soils using a complex of geophysical methods.

Methodology: a complex of geophysical methods was used, consisting of gravimetry and electrical exploration (vertical electrical sounding and electrical profiling using the resistance method, water and soil resistivity metering, surveying the gradient of the natural electric field potential). The equipment used: ERA-MAX electrical exploration complex, GNU-KV gravimeters.

Results and discussion: the valley of the small Milchanka River buried during urban construction was studied. The erosional incision of the river is reflected in the form of a negative anomaly of the gravitational field with an amplitude of 0.5−1.16 mGal and a width of about 200 m. During the interpretation of the results of gravimetric studies, the parameters of the decompaction zone corresponding to the buried incision were determined. Electrical profiling showed that the loosening of the rock mass is due to the absence of a moraine in the uppermost part of the section (an increase in apparent resistivity at a spacing of AB=60 m) and a layer of Paleogene sandstones at a depth of more than 25 m (a decrease in apparent resistivity at a spacing of AB=200 m). According to the interpretation of electrical exploration data, the buried valley of a small river is a drain for sediments infiltrating from the built-up surface, in which there are no impermeable layers, which causes a high risk of groundwater pollution. Conclusion: the proposed complex of gravimetry and electrical exploration allows for prompt and sufficiently complete mapping of an erosional incision buried in an urban area and an assessment of environmental and geological risks.