# EXISTING ISSUES OF HYDROLOGY CALCULATIONS. PART 1

Section
Scientific discussions
• Alexey Yu. Vinogradov Scientific and Industrial Research Association Gidrotehproekt, Valday, Russia, Saint Petersburg State Forest Technical University, St. Petersburg, Russia
• Arkady M. Doganovsky Russian State Hydrometeorological Uni-versity, St. Petersburg, Russia
• Victor A. Obyazov Scientific and Industrial Research Associa-tion Gidrotehproekt, Valday, Russia
Keywords: probabilistic methods, hydrology calculations, river flow, the frequency of occurrence of extreme water flow, accuracy of measuring maximum water flow
(+) Abstract

The article begins a discussion on the validity of applying methods of probability theory and mathematical statistics in hydrology calculations. The methodology of river flow calculations nowadays is based on the statistical processing of observation datas. These methods are specified in prescriptive documents (such as SR 33-101-2003) and, in fact, are required for using in engineering calculations. Any other alternative methods are not advisable. However, our experience of using probabilistic-statistical methods in engineering-hydrometeorological surveys let us to doubt the propriety of such application.

It is questionable whether the concept of a random variable is applied to hydrological characteristics, in particular, to water consumption. In terms of mathematics, the sample input data subsequently used in solving statistical problem is the result of an experiment conducted under unaltered conditions. Water consumption depends on many natural factors, some of which are constantly changing. In addition, dependence on some factors is almost functional. For example, precipitation causes an increase of river flow, and their absence causes a decrease. Other factors, in contrast, are quite stable. For each catchment area, they are not random and behave predictably.

For example, extrapolation of the maximum water flow rate in the region of rare probability, seems insufficiently reasoned. The error of measurements (definitions) of water flow in the river increases as its value increases. This is facilitated by the almost impossible measurement of river flow when water enters the floodplain, while floating of ice, while timber drifting on rivers, etc. The measurement methods used in these cases give an error of up to 25% by experts assessment. Herewith water flows are differs by 5-10%. Thus, we do not have the ranked values of several of the highest water flow, but some average maximum flow with regular repeatability.

As a result, it was concluded that the use of probabilistic-statistical analysis in hydrological calculations is insufficiently justified.

Scientific and Industrial Research Association Gidrotehproekt, Valday, Russia, Saint Petersburg State Forest Technical University, St. Petersburg, Russia

E-mail: gd@npogtp.ru
eLibrary SPIN-код: 3692-8409
Scopus ID: 56909443300
ORCID iD:0000-0001-6834-2507

Russian State Hydrometeorological Uni-versity, St. Petersburg, Russia

E-mail: gd@npogtp.ru
eLibrary (РИНЦ) SPIN-код: 2586-6298
Scopus ID:

Victor A. Obyazov,
Scientific and Industrial Research Associa-tion Gidrotehproekt, Valday, Russia

E-mail: td@npogtp.ru
eLibrary (РИНЦ) SPIN-код: 4590-8490
Scopus ID: 6505820654
ORCID iD: 0000-0002-9644-1286

(+) References

Aivazyan S.A., Yenyukov I.S., Meshalkin L.D. Priklad-naya statistika: Osnovy modelirovaniya i pervichnaya obrabotka dannykh: Spravochnoe izd. [Applies statistics: Bases of modelling and initial data processing: reference edition]. Moscow, Publ. Finansy i statistika, 1983. 471 p. (In Russian).

Gnedenko B.V. Besedy o matematicheskoi statistike [Conversations about mathematical statistics]. Moscow, Publ. Nauka, 1968. 64 p. (In Russian).

Goroshkov I.F. Gidrologicheskie raschety [Hydrology calculations]. Leningrad, Publ. Gidrometeoizdat, 1979. 433 p. (In Russian).

Druzhinin I.P., Konovalenko Z.P., Kham'yanova N.V. Vekovye i vnutrivekovye kolebaniya stoka rek Aziatskoi chasti SSSR [Centuries-old and intra-century fluctua-tions in river flow in the Asian part of the USSR]. In Bykov V.D. (ed.) Mnogoletnie kolebaniya stoka i veroyatnostnye metody ego rascheta [Long-term flow fluctuations and probabilistic methods for its calculation]. Moscow, Publ. MGU, 1967, pp. 60-66. (In Russian).

Ivchenko G.I., Medvedev Yu.I. Vvedenie v matematich-eskuyu statistiku: uchebnik [Introduction to Mathematical Statistics]. Moscow, URSS, 2010. 600 p. (In Russian).

Fedotov G.A. Izyskaniya i proektirovanie mostovykh perekhodov: uchebnoe posobie dlya studentov uchrezhdenii vysshego professional'nogo obrazovaniya [Researches and design of bridge crossings]. Moscow, Publ. Akademiya, 2010. 304 p. (In Russian).

Kritskii S.N., Menkel' M.F. Gidrologicheskie osnovy up-ravleniya rechnym stokom [Hydrological basics of river flow management]. Moscow, Publ. Nauka, 1981. 257 p. (In Russian).

Naidenov V. I., Kozhevnikova I. A. Pochemu tak chasto proiskhodyat navodneniya [Why are floods so fre-quent?]. Priroda [Nature], 2003, no. 9 (1057), pp. 12–20. (In Russian; abstract in English).

Rozhdestvenskii A.V., Chebotarev A.I. Statisticheskie metody v gidrologii [Statistical methods in hydrology]. Leningrad, Publ. Gidrometeoizdat, 1974. 424 p. (In Rus-sian; abstract in English).

Vinogradov A.Yu. Nikiforovskii A.A. K voprosu o primenimosti statisticheskikh metodov v raschetakh maksimal'nogo stoka malykh rek [On the applicability of statistical methods in the calculation of maximum flow of small rivers]. In Kazakov N.N. (ed.), Sbornik dokladov Tret'ei Mezhdunarodnoi konferentsii «Selevye potoki: ka-tastrofy, risk, prognoz, zashchita» (g. Yuzhno-Sakhalinsk, 22-26 sentyabrya 2014 g.) [III International Conference “Debris Flows: Disasters, Risk, Forecast, Protection” (Yuzhno-Sakhalinsk, September 22-26, 2014)], Yuzhno-Sakhalinsk, Publ. of Sakhalinskii filial Dal'nevostochnyi geologicheskii institut DVO RAN, 2014, pp. 242-246. (In Russian; abstract in English).

Vladimirov A.M. Gidrologicheskie raschety [Hydrology calculations]. Leningrad, Publ. Gidrometeoizdat, 1990. 365 p. (In Russian; abstract in English).

Vodogretskiy V.E. (ed.) Resursy poverkhnostnykh vod SSSR: v 20 vol. Vol.2: Kareliya i Severo-Zapad. Chast' 2. Prilozheniya. [Surface water resources of the USSR: in 20 vol. Vol. 2: Karelia and North-West. Part 2. Applica-tions]. Leningrad, Publ. Gidrometeoizdat, 1972. 278 p. (In Russian).