Utilizing Concept of Vegetation Freeboard Equivalence in River Restoration

Lee, Jong-Seok;Julien, Pierre Y.

  • Received : 2012.07.06
  • Accepted : 2012.09.13
  • Published : 2012.09.28


The concept of vegetation freeboard equivalence (VFE) is presented from the comparison between the rise in stage with/without vegetation and the freeboard height under design discharge conditions. In South Korea, the freeboard height of large, medium and small rivers is defined as a function of river discharge. Two models are used for this analysis of flood stage with and without vegetation: the 1-D model HEC-RAS and the 2-D model RMA-2. Both models are applied to three river study sites of the Geum River in South Korea as representative sites for a large, a medium and a small river. The analysis shows that without vegetation, both models provide comparable results and the calculated results are in very good agreement with the design configuration. The vegetation effects on the medium river are less significant, and the freeboard is adequate to contain the rise in stage from the added floodplain vegetation in large rivers. The concept of vegetation freeboard equivalence is therefore useful for the analysis of flood river stages after the restoration of channels with increased floodplain vegetation.


Vegetation Freeboard Equivalence (VFE);River Restoration;Stream Rehabilitation;Levee Design;Flood Control


  1. T.C. Ackerman, M.R. Jensen and G.W. Brunner, "New floodplain delineation capabilities in HEC-RAS," Proc. ASCE, 2009, p. 1-7.
  2. H.H. Barnes, Roughness characteristics in natural channels, USGS, Washington, 1967.
  3. G.W. Brunner, HEC-RAS, River analysis system hydraulic reference manual, USACE, HEC, 2008.
  4. J. Bruxer and A. Thompson, St. Clair River hydrodynamic modelling using RMA2 Phase 1 Report, IUGLS SCRTT, Canada, 2008.
  5. BYU (Brigham Young University), The surface-water modeling system (SMS)(Ver 9.2) tutorials manual, BYU, EMRL, 2006.
  6. S.U. Choi and J. Shin, "Prediction of stage in a stream with vegetation on the floodplain," WWF, Incheon, 2009.
  7. V.T. Chow, Open Channel Hydraulics, McGraw-Hill, 1959.
  8. S.E. Darby, "Modeling effect of riparian vegetation on flow resistance and flood potential," ASCE Journal, vol. 125, no. 5, 1999, pp. 443-454.
  9. D.M. Gee, M.G. Anderson and L. Baird, Two-dimensional floodplain modeling, USACE, IWHEC, Davis, 1990.
  10. P.Y. Julien, River Mechanics. Cambridge University Press, New York, 2002.
  11. P.Y. Julien, Erosion and Sedimentation. 2nd Edition, Cambridge University Press, New York, 2010.
  12. F. Karim, "Bed configuration and hydraulic resistance in alluvial-channel flows," ASCE Journal, vol. 121, no. 1, 1995, pp. 15-25.
  13. KICT (Korea Institutive of Construction Technology), Technology development for trees management in flood plain, KICT, Seoul, 2007, p. 47-76 (in Korean).
  14. N. Kouwen and R.M. Li, "Biomechanics of vegetative channel linings," ASCE Journal, vol. 106, no. 6, 1980, pp. 1085-1103.
  15. KWRA (Korea Water Resource Association), River design criteria and explanation, KWRA, Seoul, 2009 (in Korean).
  16. J.S. Lee, River Engineering and Design. SaeRon Publish Inc., Seoul, 2010(in Korean).
  17. J.S. Lee and B.C. Kim, "Flood stage evaluation for vegetated models in river scales," KSCE Journal, vol. 30, no. 5B, 2010, pp. 509-518 (in Korean).
  18. H. Mashriqui, S. Reed and C. Aschwanden, "Toward modeling of river-estuary-ocean interactions to enhance operational river forecasting in the NOAA National Weather Service," Conference JFI, 2010.
  19. MOCT (Ministry of Construction and Transportation), Development of application and management method, river alignment and evaluation-Evaluation hydraulic stability, MOCT, Seoul, 2009(in Korean).
  20. S.K. Park et al., Improvement of maintenance enhancement methods for the Nakdong River estuary barrage, BRO K-Water, 2008(in Korean).
  21. Y.H. Shin and P.Y. Julien, "Changes in hydraulic geometry downstream of Hapcheon re-regulation dam, South Korea," IRBM Journal, vol. 8, no. 2, 2010, pp. 139-150.
  22. J.G. Song, B.C. Kim and J.S. Lee, "Evaluation of hydraulic stability for river with vegetation," Proc. KWRA, 2010, pp. 855-859 (in Korean).
  23. D. Stevenson, 1-D HEC-RAS Model and Sensitivity Analysis for St. Clair River from 1971-2007, IJCI UGLS, Ottawa, 2009.
  24. L.B. Swindon, D.N. Gee and M.G. Andeson, "Ungauged catchment modelling II. Utilization of Hydraulic models for validation," CATENA, SSHG Journal, vol. 19, 1992, pp. 33-42.
  25. P.V. Timbadiya, P.L. Patel and P.D. Porey, "Calibration of HEC-RAS model on prediction of flood for lower Tapi River, India," WRP Journal, vol. 3, 2011, pp. 805-811.
  26. USACE (U.S. Army Corps of Engineers), HEC-RAS (River Analysis System) Application guide (Ver. 4.1), USAC, Davis, 2010.
  27. C.R. Wagner and D.S. Mueller, Calibration and validation of a two-dimensional hydrodynamic model of the Ohio River, USGS, Denver, 2001.
  28. H.S. Woo et al., "Hydraulic resistance of some selected vegetation in open channel flows," RRA Journal, vol. 24, 2008, pp. 673-687.
  29. F.C. Wu, H.W. Shen and Y.J. Chou, "Variation of roughness coefficients for unsubmerged and submerged vegetation," ASCE Journal, vol. 125, no. 9, 1999, pp. 934-942.