ASSESSMENT OF ROUGHNESS COEFFICIENT VALUE
The article considers one of the main parameters while conducting water management calculations – the roughness coefficient. Up-to-date assessment of its value is carried out according to special tables or by calculation. Article presents various methods for calculating the roughness coefficient – from the reverse evaluation using the Chezy formula by the measurements to the empirical relations obtained by various specialists on the basis of field studies. In addition, the authors considered formulas for calculating the roughness coefficient based on physics. The results of calculations obtained for such formulas best fit their values obtained in the inverse way from the Chezy formula. The calculation methods presented in the article were tested on the data of gauging station on the river Polist' – near the settlement Podtopol'e for the period of 1954 year and on the river Gozovka – near the settlement Goza for the period 2014-2017.
Behind comparing the results of measurements, calculations for various formulas and estimated tabular data, the authors made the following conclusions. Pressure losses in explicit depends on the depth of the stream and the slope of the free surface, the last one implicitly characterizes the frictional of the channel. At the same water flow rates, a change in the roughness coefficient can reach tens of percent. With different filling of the channel, the roughness coefficient can change by several times, which predetermines the corresponding errors in the tabular estimation of the roughness coefficient, even for a simplified case – only for an open channel. Therefore, all the dependencies, taking into account only the granulometric of riverbed deposits, basically can not have practical application.
General conclusion: even with the same water level for simplified conditions of an open channel without vegetation, the roughness coefficient can differ by several times, which nullifies all attempts to theoretically evaluate it in the absence of direct measurements of slope, speed, and average depth.
Baryshnikov N.B. Gidravlicheskie soprotivleniya rechnykh rusel: Uchebnoe posobie [Hydraulic resistance of river channels]. Saint-Petersburg, Publ. of the Russian State Hydrometeorological University, 2003. 147 p. (In Russian)
Baryshnikov N.B., Plotkina N.P., Rublevskaya R.M. Koef-fitsienty sherokhovatosti rechnykh rusel [Roughness coef-ficients of river beds] In Baryshnikov N.B. et al. (eds.) Dinamika ruslovykh potokov i okhrana prirodnykh vod. Sbornik nauchnykh trudov (mezhvuzovskii) [Dynamics of channel flows and protection of natural waters. Collection of scientific papers (interuniversity)]. Iss. 107. Leningrad, Publ. of the Leningrad Hydrometeorological Institute, 1990,
pp. 4-11. (In Russian)
Grishanin K.V. Dinamika ruslovykh potokov [The dynam-ics of channel flows]. Leningrad, Publ. Gidrometeoizdat, 1969. 428 p. (In Russian).
Kosichenko Yu.M. Vliyanie ekspluatatsionnykh faktorov na propusknuyu sposobnost' zemlyanykh rusel kanalov [In-fluence of operational factors on ground channels capaci-ty]. Nauchnyi zhurnal Rossiiskogo NII problem melioratsii [Scientific Journal of Russian Scientific Research Institute of Land Improvement Problems], 2011, no. 3(03),
pp. 55-68. (In Russian; abstract in English)
Mamedov A.Sh. Ob opredelenii koeffitsienta sherokhova-tosti rek [On determination of the river roughness coeffi-cient]. Trudy Sed'mogo Vserossiiskogo gidrologicheskogo s"ezda (Sankt-Peterburg, 19-20 noyabrya 2013 g.) [Pro-ceedings of the Seventh All-Russian Hydrological Congress (St. Petersburg, November 19-20, 2013)]. Available at: https://clck.ru/LfhCf (In Russian).
Snishchenko B.F. K.V. Grishanin i uchenie o dinamike ruslovykh potokov [K.V. Grishanin and his doctrine on dynamics of streams flow]. Zhurnal universiteta vodnykh kommunikatsii [The journal of university of water commu-nications], 2010, iss. 2 (6), pp. 10-18. (In Russian; abstract in English).
Triandafilov A.F, Efimova S.G. Gidravlika i gidravlicheskie mashiny: uchebnoe posobie [Hydraulics and hydraulic machines: a training manual]. Syktyvkar, Рubl. of the Syktyvkar Forest Institute, 2012. 212 p.
Vinogradov A.Yu., Katsadze V.A., Ugryumov S.A., Bir-man A.R., Belen'kii Yu.I., Kadatskaya M.M., Obyazov V.A., Vinogradova T.A. Vzaimodeistvie ruslovogo potoka i dna v pogranichnom sloe [Interaction of streamflow and bottom in boundary layer] // Vse materialy. Entsiklopedicheskii spravochnik [Vse Materialy. Entsi-klopedicheskii Spravochnik]. Moscow, Publ. House "Nauka & Technology", 2019a, no. 12, pp. 38-43. (In Russian; ab-stract in English). DOI: 10.31044/1994-6260-2019-0-12-38-43
Vinogradov A.Yu., Minaev A.N., Kadatskaya M.M., Kuchmin А.V., Hvalev S.V. Raschet znachenii parametrov I.I. Nikuradze i T. Karmana v zavisimosti ot temperatury vody i krupnosti donnykh otlozhenii [Calculation of con-stant J. Nikuradze and T. von Karman depending on water temperature and the size of bottom sediments] Izvestia Sankt-Peterburgskoj Lesotehniceskoj Akademii [Izvestia Sankt-Peterburgskoj Lesotehniceskoj Akademii], 2019b, is. 228, pp. 196-204. (In Russian; summary in English). DOI: 10.21266/2079-4304.2019.229.196-204
Zheleznyakov G.V. Propusknaya sposobnost' rusel i kanalov rek [Disharge capacity of channels and river beds]. Leningrad, Gidrometeoizdat Publ., 1981. 308 p. (In Rus-sian; abstract in English)
Abstract views: 71 PDF Downloads: 0
This work is licensed under a Creative Commons Attribution 4.0 International License.