Downstream Reaches Using the CCHE2D Software (Case Study the Karkheh Dam)
Subject Areas : Article frome a thesisAli Leagat 1 , Arash Adib 2 , Hamid Reza Ghafouri 3
1 - PhD Candidate, Civil Engineering Department, Engineering Faculty, Shahid Chamran University, Ahvaz, Iran
2 - دانشیار گروه عمران، دانشکده مهندسی، دانشگاه شهید چمران اهواز
3 - PhD Candidate, Civil Engineering Department, Engineering Faculty, Shahid Chamran University, Ahvaz, Iran
Keywords: morphology, Dam, Erosion, Meander, CCHE2D model,
Abstract :
Stability of streambeds is dependent on different factors some of which maybe destabilized at any moment. Dam erection on the riverbed is the most important among those factors. Some
morphological changes of a meandering river, the most obvious of which are the gradient change and the area deducted or added to the riverbed, were studied downstream of the Karkheh Dam. To delineate the areas, which had been taken from or added to the riverbed due to the lateral and longitudinal displacement of the meanders, morphology of the downstream river bed prior to and after the dam construction were studied employing satellite imagery, and their extent was calculated using the CCHE2D model. Slope reduction, as expected, follows an increase in the riverbed breadth. The average width of the riverbed was reduced from 273 m to 60 m (78% reduction) after the dam construction. The land taken off the streambed was almost 21 hectares for each kilometer of the length of the river. Mean, maximum and minimum horizontal thalweg displacements were 340,768 and 53 meters, respectively; 56% of the displacements were towards right (west) and 59% of the displacement took place out of the original streambed. The mean annual lateral displacement of the riverbed was 34 meters after the dam construction. This finding illustrates the instability of the terrain through which the river flows.
1) Avila, H., Vargas, G., and Daza, R. 2015. Susceptibility analysis of river bank erosion based on exposure to shear stress and velocity combined with hydrologic and geomorphologic variables. In World Environmental and Water Resources Congress 2014@ sWater Without Borders.ASCE.
2) Brandt, S.A. 2000. Classification of geomorphological effects downstream of dams. Catena 40: 375-401.
3) Constantine, J.A., McLean, S.R., and Dunne, T. 2010. A mechanism of chute cutoff along large meandering rivers with uniform floodplain topography. Geological Society of America Bulletin 122: 855-869.
4) Ervine, D.A., Babaeyan-Koopaei, K., and Sellin, R.H.J. 2000. Two-dimensional solution for straight and meandering overbank flows. Journal of Hydraulic Engineering- ASCE 126: 653-669.
5) Grant, G.E., Schmidt, J.C., and Lewis, S.L. 2003. A geological framework for interpreting downstream effects of dams on rivers. Water Science and Application: A Peculiar River 7: 203-219.
6) Güneralp, İ., and Marston, R.A. 2012. Process–form linkages in meander morphodynamics: Bridging theoretical modeling and real world complexity. Progress in Physical Geography 36: 718-746.
7) Huang, J., Greimann, B.P., and Randle, T.J. 2014. Modelling of meander migration in an incised channel. International Journal of Sediment Research 29: 441-453.
8) Karmaker, T., and Dutta, S. 2016. Prediction of short-term morphological change in large braided river using 2D numerical model. Journal of Hydraulic Engineering- ASCE 142: 0001167.
9) Kurowski, M. 2012. Procedural generation of meandering rivers inspired by erosion. Warsaw University of Technology.Warsaw,Poland (00-661.(
10) Lott, C.A., Wiley, R.L., Fischer, R.A., Hartifield, P.D., and Scott, J.M. 2013. Interior least tern (Sternula antillarum) breeding distribution and ecology: Implications for population-level studies and the evaluation of alternative management strategies on large, regulated rivers. Ecology and Evolution 3: 3613-3627.
11) Narinesingh, P., and Pizzuto, J.E. 2009. Applying a model of curvature-driven bend migration developed for alluvial rivers to a gravel-bedded river with reaches of exposed bedrock. In: AGU Fall Meeting Abstracts.
12) Nelson, N.C., Erwin, S.O., and Schmidt. J.C. 2013. Spatial and temporal patterns in channel change on the Snake River downstream from Jackson Lake dam, Wyoming. Geomorphology 200: 132-142.
13) 13.Overeem, I., Kettner, A.J., and Syvitski, J.P.M. 2013. Impacts of humans on river fluxes and morphology. Treatise of Geomorphology 9: 828-842.
14) 14.Patra, K.C., Kar, S.K., and Bhattacharya, A.K. 2004. Flow and velocity distribution in meandering compound channels. Journal of HydraulicEngineering- ASCE 130: 398-411.
15) 15. Richard, G.A., and Julien, P.Y. 2003. Dam impacts on and restoration of an alluvial river Rio Grande, New Mexico. International Journal of Sediment Research 18: 89-96.
16) 16. Richard, G.A., Julien, P.Y., and Baird, D.C. 2005. Case study: modeling the lateral mobility of the Rio Grande below Cochiti Dam, New Mexico. Journal of Hydraulic Engineering- ASCE 131: 931-941.
17) 17. Shin, Y.H., and Julien, P.Y. 2010. Changes in hydraulic geometry of the Hwang River below the Hapcheon Re-regulation Dam, South Korea. International Journal of River Basin Management 8: 139–150.
18) 18. Shin, Y.H., and Julien, P.Y. 2011. Effect of flow pulses on degradation downstream of Hapcheon Dam, South Korea. Journal of Hydraulic Engineering- ASCE 137: 100-111.
19) 19. Stevaux, J.C., Martins, D.P., and Meurer, M. 2009. Changes in a large regulated tropical river: The Paraná River downstream from the Porto Primavera Dam, Brazil. Geomorphology 113: 230-238.
20) 20.Surian, N., and Rinaldi, M. 2003. Morphological response to river engineering and management in alluvial channels in Italy. Geomorphology 50: 307-326.
21) 21. Wang, G., Xia, J., and Wu, B. 2008. Numerical simulation of longitudinal and lateral channel deformations in the braided reach of the Lower Yellow River. Journal of Hydraulic Engineering- ASCE 134: 1064-1078.
22) 22. White, W.R., Bettes, R., and Paris, E. 1982. Analytical approach to river regime. Journal of the Hydraulics Division- ASCE 108: 1179-1193.
23) 23. Yuba County Water Agency. 2010. Channel morphology downstream of Englebright Dam, FERC Project No. 2246 p.1-10.
24. Zámolyi, A., Szĕkely, B., Draganits, E., and Timár, G. 2010. Neotectonic control on river sinuosity at the western margin of the Little Hungarian Plain. Geomorphology 122: 231-243.
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