When studying the problems of water filtration to a single horizontal imperfect drain of finite length, in a system of interacting horizontal imperfect drains, it is necessary to consider spatial (three-dimensional) filtration problems. Unlike flat (two-dimensional) problems, spatial filtering has been studied in less detail, since it is difficult to obtain rigorous solutions to their problems.

Keywords: water supply facilities, filtration, equipotentials, drainage, borehole, pressure reservoir, drain, pressure, inflow, reservoir, watercourse

The analysis of N.N. Pavlovsky's method for calculating the parameters of the riverbed in the branches is given. The reasons for the limitation of this method have been established. The Lagrange transform is used to find the extremum of the objective function for equations of uneven fluid motion, which makes obtaining an equivalent resistance modulus highly visual and easy to use. The results of the experiment are presented.

Keywords: calculation method, multi-node sections of rivers, resistance modulus, N.N.Pavlovsky method

Pipeline fittings, which include butterfly valves, are not unimportant in pipeline systems. The main function of this design element is to prevent emergencies in pipeline systems. The principle of operation is based on closing of the shut-off device in case of change of direction of the transported medium flow. This ensures reliable flow control and prevents backflow of the medium in the pipeline. The rotary check valve provides reliability, tightness and safe operation of systems, as well as durability with regard to safety requirements. The article deals with the design and calculation of rotary check gates. The purpose of development of such a model range is to create a durable and reliable design, which will be able to ensure during the whole service life a safe operation in production with different parameters of the working environment. To confirm the reliability and serviceability parameters of the design, strength calculation of the butterfly valves has been carried out. As a result of numerical modelling of all designed check gates, the calculated parameters allow to give positive assessment to the gates and confirm compliance with technical requirements.

Keywords: rotary check gate, modelling, mathematical modelling, finite element method, calculation of reliability indices

The method of numerical calculation of the parameters of the river channel in the arms is given. The method of nonlinear programming for analysis of dissipative systems with concentrated parameters is used. The technique is focused on computer modeling in the environment of engineering package MathCad. The results of the experiment are given.

Keywords: Distribution of water flow, calculation method, multi-node sections of rivers, water flow