Irrigation and Drainage Systems

, Volume 11, Issue 2, pp 171–184 | Cite as

Flow resistance and hydraulic capacity of water courses with aquatic weed growth. Part 2

  • E.P. Querner


The flow resistance is generally derived from fieldmeasurements, using the total wetted area of the cross-section.Less attention has been paid to the aquatic weed growth stageand often different resistance have been derived. In this paperthe flow resistance required in the Manning formula wascalculated from laboratory experiments and field data. A goodsolution appeared to be using the unobstructed part of the cross-section only and excluding the part covered by weeds. Apractical solution was found using the relative weed obstructionin the water courses to represent the weed growth. Weedobstruction was measured throughout the growing season. Thedata were obtained from water courses without any weedcontrol and also in sections where weeds were cleared twiceduring the growing season.

flow resistance laboratory experiments unobstructed part weed growth hydraulic radius drainage canal 


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  1. Chow V.T. 1959. Open channel hydraulics. McGraw-Hill Book Co. Inc., New York. 680 pp.Google Scholar
  2. Dawson F.H. 1988. Water flow and vegetation of running waters. In: Vegetation of inland waters. Ed. J.J. Symoens. Kluwer Academic Publishers, Dordrecht: 283–309.Google Scholar
  3. Pieters J. & Flach A.J. 1966. Verandering in de wandruwheidsfactor van open waterlopen tijdens het groeiseizoen. Waterschapsbelangen 51(18): 257–261, 273–277.Google Scholar
  4. Nitschke E. 1983. The influence of overgrowing with herbs on hydraulic parameters of agricultural outfalls and ditches. Proc. 20th Congress Int. Assoc. of Hydraul. Res. Moscow: 327–329.Google Scholar
  5. Pitlo R.H. 1990. Oversizing and reduced maintenance in relation to aquatic plant growth and flow resistance. Proceedings EWRS, 8th Symp. on Aquatic Weeds, Upsala: 167–172.Google Scholar
  6. Querner E.P. 1993. Aquatic weed control within an integrated water management framework. Wageningen Agricultural University. Doctoral thesis. Also as: Report 67. DLO Winand Staring Centre, Wageningen, The Netherlands. 204 pp.Google Scholar
  7. Querner E.P. 1997. A model to estimate timing of aquatic weed control in drainage canals. Irrigation and Drainage Systems11: 157–169 (in this issue).Google Scholar
  8. Vermaat J.E. & Van Viersen W. 1990. Growth potential for weeds in rivers (in Dutch). H2O 23(20): 534–536.Google Scholar

Copyright information

© Kluwer Academic Publishers 1997

Authors and Affiliations

  • E.P. Querner
    • 1
  1. 1.Soil and Water Research (SC-DLO)DLO Winand Staring Centre for Integrated LandWageningenThe Netherlands

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