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| Titel |
A methodological approach of estimating resistance to flow under unsteady flow conditions |
| VerfasserIn |
M. M. Mrokowska, P. M. Rowiński, M. B. Kalinowska |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 19, no. 10 ; Nr. 19, no. 10 (2015-10-05), S.4041-4053 |
| Datensatznummer |
250120818
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| Publikation (Nr.) |
 copernicus.org/hess-19-4041-2015.pdf |
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| Zusammenfassung |
| This paper presents an evaluation and analysis of resistance parameters:
friction slope, friction velocity and Manning coefficient in unsteady flow.
The methodology to enhance the evaluation of resistance by relations derived
from flow equations is proposed. The main points of the methodology are
(1) to choose a resistance relation with regard to a shape of a channel and
(2) type of wave, (3) to choose an appropriate method to evaluate slope of water
depth, and (4) to assess the uncertainty of result. In addition to a critical analysis of
existing methods, new approaches are presented: formulae for resistance
parameters for a trapezoidal channel, and a translation method instead of
Jones' formula to evaluate the gradient of flow depth. Measurements obtained from
artificial dam-break flood waves in a small lowland watercourse have made it
possible to apply the method and to analyse to what extent resistance
parameters vary in unsteady flow. The study demonstrates that results of
friction slope and friction velocity are more sensitive to applying
simplified formulae than the Manning coefficient (n). n is adequate as a flood
routing parameter but may be misleading when information on trend of
resistance with flow rate is crucial. Then friction slope or friction
velocity seems to be better choice. |
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