This paper deals with results of a systemized overview of the Chézy roughness coefficient calculation problem as one most frequently used empirical characteristics of hydraulic resistance. The overview is given in the context of the formation of reliable empirical data needed to support hydro-engineering calculations and mathematical modelling of open flows in river channels. The problem topicality is because of a large number of practical tasks which need such a pre-research. In many cases, the accuracy of determining empirical hydraulic resistance characteristics can largely affect the accuracy of solving tasks relating to designing hydraulic structures and water management regardless of chosen mathematical models and methods.Rivers are characterized by a significant variety of flow conditions; hydraulic resistance to flows in rivers can thus vary widely determining their flow capacity. Considering the variety of river hydro-morphology and hydrology, the Chézy roughness coefficient often appears to be the most complete characteristic of hydraulic resistance to open flows in river channels comparing with other integral empirical characteristics of hydraulic resistance.At present, there are a large number of empirical and semi-empirical formulas to calculate the Chézy roughness coefficient. The main aim of this study was to analyze and systematize them in the context of providing proper support to the open channel hydraulics tasks. To achieve the aim of the study, a literature review regarding the problem of determining the integral hydraulic resistance characteristics to open flow in river channels was performed, as well as formulas used to calculate the Chézy roughness coefficient in practice were explored and systemized. In total, 43 formulas to calculate the Chézy roughness coefficient, as well as 13 formulas that can be used to estimate the Manning roughness coefficient were analyzed and systematized. Based on all these formulas, about 250 empirical equations can be compiled to calculate the Chézy coefficient depending on hydro-morphological peculiarities of rivers and river channels, hydraulic conditions, formulas application limits, and so on.
There has been presented a method of situational predictive modelling of the flood hazard in the Dniester River valley near the town of Halych based of hydrological observations data obtained at the Halych water level gauge. Some features in the behaviour of the equation of relationship between levels and water discharges for the Halych water level gauge were revealed, in particularly, regularities fostering reliable forecasting the flood hazard by means of statistical data and ambiguities interfering similar predicting. The possibility of effective situational predicting of the flood hazard according to current data of hydrological observations to minimize probable harm and losses was shown.
mathematical modeling when managing the resource portfolio of the enterprise. At the same time, when identifying the structure of such a portfolio and assessing the weight of its individual elements, the gender factor consideration can be important.
the city of Nova Kakhovka, Kherson region [1]. This is the last sixth step of the Dnieper River system of hydroelectric power plants (HPP). Construction work at the Kakhovka hydroelectric complex began in the spring of 1952; the hydraulic facilities were put into permanent operation in 1959. In the summer INDUSTRY CONTROL SYSTEMS
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