Third EAGE Workshop on Assessment of Landslide Hazards and Impact on Communities

The results of structural and tectonic research within the model objects of the Middle Dnieper are presented. Based on the analysis of fracturing of Eocene rock complexes and data of field geological and geomorphological studies of the Rzhyshchiv area (Kyiv Prydniprovya), the influence of the structural- tectonic factor on the formation and activation of landslides is confirmed.

Our study considers potential further activization of landslide at O. Fomin Botanical Garden in Kyiv. It belongs to the upper tier landslides, within which the loess-like loams slide by the interface with variegated clay horizon. We have conducted Electrical Resistivity Tomography measurements on stable block of loess deposits in order to estimate variations of geomechanical properties of deposits indirectly. The range of the electrical resistivity values is limited to variations between 0 and 200 Ω m. Two landslide-prone areas occupying northern and southern slope of the investigated hill were identified by ERT. At the southern slope the potential size of block which is “ready” to cracking-sliding failures is 5x5 m. The angle of the potential sliding surface is close to 70%. The southern slope is extremely water saturated. The studied area requires anti-landslide measures to minimize the impact on the unique ecosystem of the Botanical Garden.

The methodology of comprehensive assessment and forecasting of socio-economic loss inflicted and expected caused by landslides and abrasion processes taking into account, climate changes has been proposed in the article. The relevance of chain effects from the simultaneous negative impacts has been emphasized. The following outcomes have been figured out: reduction of recreational opportunities aimed at health improvement and territorial unemployment rate growth due to the number of vacationers’ drop. It has been proved that the assessment of the expected economic loss rate should include lower health and recreation stock loss caused by coastline beaches’ loss, which fuels shorten local budget revenues and number of businesses, additional unemployed assistance, and transporters’ loss. The study results’ one could use when calculating the required costs to prevent and avoid natural emergencies caused by landslides and abrasion.

The current state conditions, types and lithological composition of the northwestern part of the Black Sea shorelines are described. The aim of the work is to identification of patterns of relationships between spatio-temporal variability of abrasion-landslide processes and beach morphometric indicators, on the coastline between the Dniester and Dnieper-Bug estuaries. Observational data within the lithodynamic cells (estuaries are the natural boundaries) were studied in that research, as well as data on 7 stationary sites during 1976–2016. Models describing the relationships between abrasion-landslide indicators (cliff retreat, washout volume, landslide deformation area) and morphometric indicators of the beach (width, sediment volume) were developed. Excel and Statistica computer packages were used to process the materials. Spectral analysis was used to identify the periods of abrasion-landslide process activation. Correlation-regression analysis allows to identify a close relationship between the factors and to create regression models, which would reflect the relationship between them. These results can be used in the development of coast protection structures, recreational constructions and during artificial beaches creation.

Geoelectrical investigations, carried out in the month of September 2014, aimed to obtain indirect information on the geological structure of the subsoil and identify the causes of instability phenomena produced in recent years, with serious consequences for a significant number of construction and road and villages Gornet and Cuib. Since the area of land affected by movements in an area is occupied by houses, enclosures, courtyards and gardens of the locals, location and length of the profiles were determined by measuring doorways available for stretching cables. This work is presented with the support of Nucleu- Program financed by the Ministry of Research, Innovation and Digitalization of Romania.

Purpose of the work has been to identify deformation processes of wave nature in the geological environment on an example of some landslide sites in the North-Western Black Sea area (Ukraine). Methodology. Analysis of geodetic monitoring has been carried out for the landslide slopes located a) on the right bank of the Malyi Adzhalyk Liman (2000–2019); b) on a site on the Black Sea north-west coast (1973–1987). Results and Discussion. It has been established that modern dynamics of landslide slopes is significantly influenced by the periodically changing in space and time stressed-deformed state of the rock. Empirically revealed characteristics of spatial & temporal migration of modern deformations within the landslide slopes have been interpreted by the authors as the occurrence of the rotation dynamics- managed wave geodynamics processes having different periodicity in the upper levels of the Earth’s crust. Conclusions. For correct preparation of calculation schemes, it is important to take into account both the mechanism of landslide forming and the factors bringing down the general slope stability. Among those factors is quasi-periodical variability of stressed-deformed state of the rock massif managed by wave deformation processes of different hierarchical levels.

The purpose of this paper is to model the stresses distribution within slopes based on elastic potential field (EPF) theory and complex variable boundary element method (CVBEM) for assessing the stability of slopes. Methodology. Potential field theory and CVBEM are combined here in new ways to examine the deformation and stability of heterogeneous slopes. For two-dimensional problem we have used the elastic field potential which is twice the mean effective normal stress and satisfies the Laplace equation. The elastic stresses can be predicted from this potential, permitting calculation of local factors of safety and prediction of potential slip surface locations. Results. Mathematical simulation demonstrates the application of EPF method to the slopes underlain by heterogeneous layers. The isopotential and force lines refract at the interface between layers with different geomechanical characteristics, causing EPF grid to warp. Isopotential lines and stresses concentrate in the stiffest layers which retard the development of landslides. In contrast, stresses relax and force lines concentrate in the weak layers, making those layers prone to slip. Conclusions. The EPF method can model stress distribution within heterogeneous slopes and to assess their stability. The application of our model to the Odessa landslides shows that it yields useful results.

The tendency to increase the frequency of exogenous geological processes due to man-made impact determines the relevance of the study. The territory of the city of Kyiv is characterized by the presence of sloping areas, which are built up and continue to be built up intensively. Timely detection of areas of dangerous geological processes and the application of measures to prevent the development of landslides will avoid significant losses. An important factor in the reliability of calculations of the stability of slopes and landslides is to take into account the impact of groundwater. Different calculation methods, different complexity of their implementation and ambiguity of the results exacerbate the problem, especially in the issue of fluctuations in groundwater levels and its subsequent impact on the parameters of stability. The role of natural and man-caused components of infiltration supply in the forecast assessment of groundwater, especially groundwater levels has been studied.

The technology and methodology of field electrical exploration observations in the modification of vertical electrical sounding (VES) have been developed, the results of interpretation of studies in combination with gravity prospecting, which were carried out by the Dnepropetrovsk geophysical expedition “Dneprogeofizika” in 2018 and 2020 years on the territory of the southern engineering- geological region of the Krivoy Rog iron ore basin (Kryvbas). The considered approach made it possible to study in detail the potential zones of increased permeability of rocks, zones of possible filtration of highly mineralized waters, the establishment of the features of the geological section of sedimentary rocks and tectonic disturbances in the study area. Over the past 35–40 years, there has been a significant activation of sinkhole-landslide processes associated with significant pollution by technogenic waters of underground water basins. The results obtained confirm the confinement of landslides to the decompacted areas of the minimum of the gravitational field, coinciding with the subvertical linear zones of increased and decreased values of apparent resistivity on the geoelectric sections correspond to weakened zones of rocks (faults, fracturing).

The territory of historic Kyiv has long attracted people with its advantageous geographical location and natural protection from enemy attacks. Recently, Kyiv officially celebrated 1.5 thousand years. During this time, it grew and became the “Greater Kyiv” - an agglomeration, which includes the actual Kyiv within its current boundaries and adjacent settlements, which are interconnected by industrial and other structural relations.

The geomorpholithosphere of Greater Kyiv is characterized by a high valley coefficient. It contains fragments of up to 12 generations of buried valleys, which together form the Paleozoic-Cenozoic valley formation, which systematically organized, what is important for predicting underground hydrodynamics. The structure and dynamic features of the geodynamic body of the geomorpholithosphere affect the objects of the natural-technogenic system of Kyiv and should be taken into the spatial planning of Kyiv.