Prediction of Percentage Discharge Distribution in Non-Prismatic Compound Channels with Skewed Floodplains

Document Type : Research Paper

Authors

Department of Civil Engineering, Bu-Ali Sina University, Hamedan, Iran.

Abstract

In rivers with non-prismatic compound cross-sections, due to the change in cross-section along the channel, mass exchange between the main channel and floodplains. Therefore, discharge distribution in non-prismatic compound channels is an important task for river and hydraulic engineers. In this paper, some results of experiments performed in non-prismatic compound channels with skewed and inclined floodplains have been explained. Two skew angles of 3.81o and 11.31o and three discharges were investigated. The effects of relative depth and relative distance on percentage discharge distribution in each sub-section of the skewed compound channels are presented. The experimental results show that the percentage discharge in each sub-section relies upon the parameters like relative depth, relative distance, skew angle, and floodplain side slope. By using the experimental results, multivariable regression models have been developed to estimate the percentage of discharge in the main channel and on the floodplains. Investigations indicate that the regression models presented in this research, in the validation range, can predict the percentage of discharge in each sub-section of the skewed compound channel fairy well. So that for the results used in this research, the coefficient of determination (R2) for predicting discharge regression model in the main channel is 0.96, on the diverging floodplain is 0.92, and on the converging floodplain is 0.91. Also, the mean absolute percentage errors (MAPE) between the calculated and measured value of percentage discharge in the main channel, on the diverging floodplain, and the converging floodplain are equal to 1.47%, 14.29%, and 21.7%, respectively.

Keywords

References

  1. Sellin, R. H. J. (1964). A Laboratory Investigation into the Interaction between the Flow in the Channel of a River and that over its Flood Plain. La Houille Blanche, pp: 7: 793-802.
  2. Knight, D. W., Demetriou, D. (1983). Flood Plain and Main Channel Flow Interaction. Journal of Hydraulic Engineering. ASCE, pp: 109(8): 1073-1092.
  3. Ackers, P. (1993). Flow Formulae for Straight Two-Stage Channels. Journal of Hydraulic Research. IAHR, pp: 31(4): 509-531.
  4. Lambert, M. F., Sellin, R. H. J. (1996). Discharge Prediction in Straight Compound Channels Using the Mixing Length Concept. Journal of Hydraulic Research. IAHR, pp: 34(3): 381-394.
  5. Bousmar, D., Rivière, N., Proust, S., Paquier, A., Morel, R., Zech, Y. (2005). Upstream Discharge Distribution in Compound-Channel Flumes. Journal of Hydraulic Engineering. ASCE, pp: 131(5): 408-412.
  6. Khatua, K. K., Patra, K. C., Mohanty, P. K. (2012). Stage-Discharge Prediction for Straight and Smooth Compound Channels with Wide Floodplains. Journal of Hydraulic Engineering. ASCE, pp: 138(1): 93-99.
  7. Bousmar, D. (2002). Flow Modelling in Compound Channels: Momentum Transfer between Main Channel and Prismatic or Non-Prismatic Floodplains. PhD Thesis, University of Catholique de Louvain, Louvainla, Belgium.
  8. Chlebek, J. (2009). Modelling of Simple Prismatic Channels with Varying Roughness Using the SKM and a Study of Flows in Smooth Non-Prismatic Channels with Skewed Floodplains. PhD Thesis, University of Birmingham, Birmingham, UK.
  9. Bousmar, D., Wilkin, N., Jacquemart, J. H., Zech, Y. (2004). Overbank Flow in Symmetrically Narrowing Floodplains. Journal of Hydraulic Engineering. ASCE, pp: 130(4): 305-312.
  10. Rezaei, B. (2006). Overbank Flow in Compound Channels with Prismatic and NonPrismatic Floodplains. PhD Thesis, University of Birmingham, Birmingham, UK.
  11. Rezaei, B., Knight, D. W. (2011). Overbank Flow in Compound Channels with Nonprismatic Floodplains. Journal of Hydraulic Engineering. ASCE, pp: 137(8): 815-824.
  12. Naik, B., Khatua, K. K., Wright, N. G., Sleigh, A. (2017). Stage-Discharge Prediction for Converging Compound Channels with Narrow Floodplains. Journal of Irrigation and Drainage Engineering, pp: 143(8): 04017017-10.
  13. Bousmar, D., Proust, S., Zech, Y. (2006). Experiments on the Flow in a Enlarging Compound Channel. Proceedings of the River Flow 2006, Lisbon, Portugal, Taylor and Francis\Balkema, pp: 1: 323-332.
  14. Yonesi, H. A., Omid. M. H., Ayyoubzadeh, S. A. (2013). The Hydraulics of Flow in Non-Prismatic Compound Channels. Journal of Civil Engineering and Urbanism, pp: 3(6): 342-356.
  15. Das, B. S., Khatua, K. K. (2018). Flow Resistance in a Compound Channel with Diverging and Converging Floodplains. Journal of Hydraulic Engineering. ASCE, pp: 144(8): 04018051-21.
  16. James, M., Brown, B. J. (1977). Geometric Parameters that Influence Floodplain Flow, Waterways Experiment Section. Report H-77-1, Hydraulics Laboratory, US Army Corps of Engineering, Vicksburg, Mississippi.
  17. Jasem, H. K. (1990). Flow in Two-Stage Channels with the Main Channel Skewed to the Flood Plain Direction. PhD Thesis, University of Glasgow, Glasgow, Scotland.
  18. Elliott, S. C. A., Sellin, R. H. J. (1990). SERC Flood Channel Facility: Skewed Flow Experiments. Journal of Hydraulic Research. IAHR, pp: 28(2): 197-214.
  19. Sellin, R. H. J. (1995). Hydraulic Performance of a Skewed Two-Stage Flood Channel. Journal of Hydraulic Research. IAHR, pp: 33(1): 43-64.
  20. Bousmar, D., Jacqmin, T., Wyseur, S., Van Emelen, S. (2012). Flow in Skewed Compound Channels with Rough Floodplains. Proceedings of the River Flow 2012., San Jose, Costa Rica, CRC Press, pp: 1: 217-224.
  21. Dolati Mahtaj, M. (2021). Experimental Study of Flow in Skewed Compound Channel with Inclined Floodplains. MSc Thesis, Bu-Ali Sina University, Hamedan, Iran. (in Persian)
  22. Dolati Mahtaj, M., Rezaei, B. (2021). Experimental Study of Force Balance and Interaction between Flow in the Main Channel and on the Floodplains in Skewed Compound Channel with Inclined Floodplains. Ferdowsi Civil Engineering, pp: 34(2): 87-102. (in Persian)

Files

Share

How to cite

Statistics