Construction of large hydropower complex is accompanied by a signifi cant technological impact on the environment. Large volumes of soil are redistributed, groundwater regime varies, there is the risk of deformation of the earth surface. One of the main methods of monitoring this dangerous phenomenon is the application of GNSS technology. The implementation of this method without a loss of coordinate accuracy depends on the conditions of horizon openness on the point of observations and the absence of objects causing multibeam eff ect, what is not always possible. This condition is not implemented on all points. Conducting high accuracy linear and angular observations in a complex with GNSS measurements will allow provide the necessary accuracy for the determination of the coordinates and their displacements. Main Research of the Problem

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The purpose of the study is to attempt to determine the deviation of vertical lines using trigonometric levelling and Global Navigation Satellite System (GNNS) measurements. For the last decades with the emergence of highprecision electronic theodolites and tacheometers, trigonometric levelling becomes a competitor of the geometric levelling of the II and III accuracy classes. This is primarily the definition of exceedances at distances up to 1-2 km for topographic surveying and the study of geodynamic processes in zones of the man-made load. Today, high precision robotic electronic tacheometers have been developed, which allow to significantly improve the accuracy of the measurement of zenith distances by automatically guiding the target to the maximum reflected signal. Such robotic tacheometers carry out measurements of anti-aircraft distances and distances without the direct participation of the observer. The method of achieving this goal is provided by theoretical and experimental studies to improve the accuracy of trigonometric alignment and the use of high-precision GNSS measurements. It is also important here to switch from the spatial geodetic coordinates B, L, H to local topocentric coordinates in order to provide control over the deformation of hydraulic structures and the territory of man-caused loading of the main structures in the area at the Dniester hydroaccumulation power plant (DHPP). The main result of the study is the possibility of taking into account the influence of the refraction and the gravitational field of the earth on the accuracy of the trigonometric levelling and the determination of the deviations of vertical lines from a two-way trigonometric levelling with short distances from 500 to 1000 m. Scientific novelty: the proposed approach allows to calculate the effect of the refraction and the gravitational field of the Earth on the resulting trigonometric levelling with high accuracy. In addition, using trigonometric levelling and GNSS measurements, it is possible to independently determine the deviation of the vertical lines. Practical significance: the proposed method makes it possible to estimate the effect of vertical lines on the results of two-way synchronous trigonometric levelling.

The purpose of this paper is to determine the optimal method of researching the vertical displacements of buildings and stability of the marks, on the basis of which it is possible to make a conclusion about the subsidence of the researched building. Methodology. The main task of geodetic observations for buildings monitoring is to identify changes in the spatial position of load-bearing structures (vertical and horizontal displacements) to assess the risk of structures destruction, dismantling unstable structures, forecasting accidents. In this paper we offered to carry out monitoring by a method of high – precision geometrical leveling on the established geodetic marks, according to one scheme with constant points of devices installation. For testing this method 13 cycles of II class leveling were conducted to determine the vertical displacements of sedimentary marks of the “Shuvar” mall building. To detailed determination of the building deformation, namely its sediment on two floors, we laid 70 marks in the floor on the first floor and 41 marks on the second floor. Stainless steel anchors were used as marks. Findings. According to the results of observations of the laid sedimentary marks we determined their conditional heights. The difference of determined heights of the same marks for a certain period of time allows to determine the vertical displacements. The results of measurements were equilibrated by the nodal point method, and the leveling line was closed on each floor, so the equilibrations were performed separately for each floor. As a result we obtained the heights of sedimentary marks and the mean square errors of their determination. We constructed schedule of heights change of the chosen marks of the first floor within 13 cycles andcarried out the analysis of the reasons of these changes. Practical implications and originality. Observations of landslides, subsidences and deformations of the building have great importance for determining the strength and stability of the building to prevent its destruction or give signal in a timely manner of an emergency, which can become vital. In this paper method for monitoring the vertical displacements of buildings is proposed and tested. The obtained results suggest that proposed method of observations can be recommended to determine the vertical displacements of such buildings and complexes.