In 2022 the 150th anniversary of the organization of the Western Expedition to drain the swamps, led by General I. I. Zhilinsky, is celebrated. This grandiose event, even for today, lasted for 30 years (1872‒1902) and affected more than 8 million hectares of the Polesie region. Today's reclamation transformation of Belarus is based on the scientific and practical work of a team of talented and selfless scientists and engineers who laid the foundations for reclamation of swamps in the Belarusian Polesie, as well as in Russia and Ukraine at the turn of the 19th ‒ 20th centuries.

The calculation of the hydraulic parameters of the nozzle of the drainage flushing device was carried out. The flow rate, speed and strength of nozzle jets are determined depending on the diameter and number of its holes for given characteristics of the device. Optimal hydraulic parameters of the jets were determined according to the force of impact on silting in the drainage.

The results of studying the operating modes of siphon catchments on the drainage and irrigation system of vertical drainage in the Polesie region in order to determine the conditions for the stability of their operation have been described. The parameters of the studied siphon catchments and the factors affecting its stable and stable operation, especially the amount of air entering the pipeline, are given. Minimum allowable water velocity in siphon is set to ensure its stable operation without air removal. The zones of influence of the siphon catchments on the position of the groundwater level and the contours of the drained area during the operation of linearly located wells were determined. Conclusions were made about the possibility of using siphon catchments in modern conditions as structural elements of vertical drainage in certain hydrogeological conditions.

The article presents calculations of the parameters of a vertical vibration isolation barrier from adjoining wells, cased with gas-filled cylindrical cylinders under pressure. The barrier is designed to reduce the level of ground vibrations behind it, which reduces additional dynamic forces in building structures and eliminates the development of additional vibrational settlements of foundations. Modeling was carried out by the finite element method. The ground medium was considered as a spatial elastic inertial array bounded by non-reflecting boundaries. The change in the parameters of surface oscillations behind the barrier was studied depending on the change in its geometric parameters and the frequency of forced oscillations of the source. The reliability of the application of the finite element method for calculating dynamic processes in the system "oscillation source – propagation medium – oscillation receiver" was confirmed by verification based on data from small-scale laboratory experiments. The use of a vertical barrier is effective in vibration isolation of building foundations from vibration sources located both inside and outside industrial workshops. The decrease in the amplitudes of vertical oscillations of the soil surface behind the barrier can reach 90 %.

The possibility of using the HEC-RAS software for hydraulic calculations of an open network with an assessment of the adequacy of the calculation results in relation to the methods and calculation formu-las used in Belarus is considered. Comparison of the calculation results (obtained in HEC-RAS with the recommended formulas given in the normative, reference and educational literature) showed that the obtained values have deviations from 1 to 20 %. Data analysis allows us to conclude that HEC-RAS can be used as an alternative method for hydraulic calculation of open channels.

An assessment of the costs of managing the operational regime of irrigation using water balance calculations was made. A brief literature review of the existing methods of irrigation regime control is given. It is noted that the most accurate method of controlling soil moisture is the thermostatic-weight method, however, this method is highly labor-intensive. It is proposed to use the method of soil water balance as a production method for controlling the irrigation regime. Comparison of operating costs of determining for the timing of irrigation of agricultural crops using water balance calculations according to the algorithm proposed by us and using the thermostatic-weight method showed an annual saving of 1780 rubles per 100 ha.

Various variants of the representation of the indicator of the water regime of plants in the mathematical model of crop productivity have been analyzed. It is shown that it is most approprite for the conditions of Belarus to use monthly precipitation amounts as this indicator. The results of checking the mathematical model of sugar beet yield according to the 10-year data of the Shchuchinsky State Export site (sugar beet of NZ-type) confirmed a sufficiently high accuracy of mathematical modeling. The coefficient of determination when comparing the measured and calculated yields, even without taking into account precipitation, was 0,87. Taking into account the water factor (precipitation) increased this coefficient to 0,91. Modeling the relationship of sugar beet yields with two crop-forming factors (food and moisture) allowed us to establish the optimal distribution of precipitation during the growing season (May - September) with a total amount of 410 mm for this period. According to the Shchuchin weather station, it was found that precipitation falling at the beginning of the growing season (May – June) has the greatest impact on the yield of sugar beet.