Forecasting landslide displacement values based on geodetic data

Introduction. Landslide processes can cause significant damage and require monitoring of displacement magnitudes. Geodetic methods are able to provide information on displacement magnitudes between observation cycles. At the same time, it is important to understand the nature of the process for future periods. There are various ways of forecasting landslide displacement and detecting when a landslide is likely to occur, but these involve a large amount of different information and data that are not always available for a particular site. In this connection, the question of the possibility of forecasting landslide displacement values and the probable moment of landslide failure using geodetic data remains relevant. Methods and materials. The aim of the study is to improve the accuracy of forecasting the magnitudes and velocities of landslide displacements on the basis of geodetic data, to detect the moment of possible landslide failure on the basis of data on horizontal or vertical displacements of the landslide obtained during geodetic observations of the landslide - prone slope. The study proposes a method for forecasting the magnitude and velocity of landslide displacements by analyzing the change in the coefficients of the straight line equation obtained by linear approximation of the horizontal and vertical displacements of the landslide. The method will allow to determine the moments of abrupt change in the landslide displacement rate, which may indicate a possible landslide failure. By discarding part of the data, it is possible to improve the quality of the forecast at moments of change in the landslide velocity. The initial data for the study were the planned coordinates and heights of the observation station working points in several cycles, fixed in the body of the landslide located near the reservoir of the Miatlinskaya hydroelectric power plant (HPP), in the mountainous region of the Republic of Dagestan, on the river Sulak, Russia and the landslide ‘Koi-Tash-Upper’ in the city of Mailuu-Suu, Kyrgyzstan. Results. In the course of the study the dependences of the values of the coefficients k and b of the equation of the straight line y = kx + b, obtained by linear approximation of the values of horizontal and vertical displacements of the landslide slope on the magnitude of change in the landslide displacement rate and on the number of observation cycles were determined. According to the obtained dependences, the calculation of maximum permissible values of change of Δkmax and Δbmax coefficients k and b is performed, according to which a conclusion is made about the change of landslide dynamics, its magnitude and displacement rate are determined. The application of the method allowed to increase the accuracy of the forecast for a number of landslides by 5% on average for horizontal and vertical displacements of the landslide. In a number of cases, for cycles following the moments of abrupt changes in landslide displacement rates, a part of the data was discarded and, after correction, it was possible to achieve an increase in the accuracy of forecasting horizontal landslide displacements by 27 % and vertical landslide displacements by 34 %. Discussion. The results obtained show that the method proposed in the study is suitable for forecasting uniform landslide displacements to which cripple landslides can be attributed. Conclusion. The proposed method allows to improve the quality of forecasting of landslide displacement values based on geodetic data and to supplement engineering - geological and geo - mechanical calculations with such data within the framework of an integrated approach to the study of landslide areas. Resume. The proposed method can be applied to observations of landslide displacements of slopes for which there is a set of geodetic data on displacement magnitudes. Suggestions for practical applications and directions for future research. The obtained research results can be applied for implementation of the algorithm of landslide displacement analysis for further observation periods at the sites where periodic observations of displacements by geodetic methods are carried out. Further research can be aimed at refining the forecast equations for other types of landslides, as well as for a limited number of observation cycles.