Impact of confluence on hydrological and morphological characters of the trunk stream: a study on the Manu River of North-east India

  • Jatan DebnathEmail author
  • Nibedita Das (Pan)
  • Rakhal Sharma
  • Istak Ahmed
Original Article


Tributaries play a significant role in changing flow structure of the main river through their additional discharge. A study was conducted at the point of convergence of the River Deo with the River Manu using simple geospatial technique and field work to justify the hydrological and morphological changes in downstream of the confluence point. The spatio-temporal change of both the river channels for 10 km length in upstream and downstream of the confluence point was considered. Moreover, field measurements and post-field work were carried out to examine the spatial variation of hydrodynamic characteristics like flow velocity, depth, water discharge, wetted perimeter and hydraulic radius of the selected stretches. Sieving method was applied for grain size analysis of river bed sediment samples. The result revealed that both the aggradation and degradation processes were equally active in the upstream segment of the Manu River but in downstream segment aggradation exceeded the degradation activity, though all the hydrodynamic variables were boosted up in downstream, except flow velocity. The present research highlighted that the steeper gradient of the R. Deo had enhanced its competency to transport medium-sized grains to the R. Manu, where fine grains were commonly found. Moreover, increased wetted perimeter in downstream specified more friction between channel bed and its flow consequent upon reduced flow velocity with extra sediment load accumulation.


Manu River Spatio-temporal change Channel morphological change Hydrodynamic variables Sediment analysis 



Authors cordially acknowledge the USGS (United State Geological Survey) for providing the satellite images at no cost. The authors acknowledge one anonymous reviewer for his constructive suggestions to improve the paper. Moreover, they like to extend thanks to the local people for their enthusiastic cooperation during field verification.


  1. Ashmore PE, Ferguson RI, Prestegaard KL, Ashworth PJ, Paola C (1992) Secondary flow in anabranch confluences of a braided, gravel-bed stream. Earth Surf Process Landf 17(3):299–311. CrossRefGoogle Scholar
  2. Bagnold RA (1966) An approach to the sediment transport problem from general physics: US Geol Survey Prof. Paper 422–1, p 37Google Scholar
  3. Benda L (1990) The influence of debris flows on channels and valley floors in the Oregon coast range, USA. Earth Surf Process Landf 15:457–466CrossRefGoogle Scholar
  4. Benda L, Andras K, Miller D, Bigelow P (2004) Confluence effects in rivers: interactions of basin scale, network geometry, and disturbance regimes. Water Resour Res 40(5):142–152CrossRefGoogle Scholar
  5. Best JL (1986) The morphology of river channel confluences. Prog Phys Geogr 10:157–174CrossRefGoogle Scholar
  6. Best JL (1987) Flow dynamics at river channel confluences: implications for sediment transport and bed morphology. In: Ethridge FG, Flores RM, Harvey MD (eds) Recent developments in fluvial sedimentology. Society of Economic Palaeontologists and Mineralogists, Special Publication, vol 39, pp 27–35CrossRefGoogle Scholar
  7. Best JL (1988) Sediment transport and bed morphology at river confluences. Sedimentology 35:481–498CrossRefGoogle Scholar
  8. Best JL, Reid I (1984) Separation zone at open-channel junctions. J Hydraul Eng 110:1588–1594CrossRefGoogle Scholar
  9. Best JL, Rhoads BL (2008) Sediment transport, bed morphology and the sedimentology of river channel confluences. In: Rice SP, Roy AG, Rhoads BL (eds) River confluences, tributaries and the fluvial network. Wiley, Chichester, pp 45–72. CrossRefGoogle Scholar
  10. Best JL, Roy AG (1991) Mixing layer distortion at the confluence of unequal depth channels. Nature 350:411–413CrossRefGoogle Scholar
  11. Biron PM, Lane SN (2008) Modelling hydraulics and sediment transport at river confluences. In: Rice SP, Roy AG, Rhoads B (eds) River confluences, tributaries and the fluvial network. Wiley, Chichester, pp 17–43CrossRefGoogle Scholar
  12. Biron P, Roy AG, Best JL, Boyer CJ (1993) Bed morphology and sedimentology at the confluence of unequal depth channels. Geomorphology 8:115–129CrossRefGoogle Scholar
  13. Biron P, Best JL, Roy AG (1996) Effects of bed discordance on flow dynamics at open channel confluences. J Hydraul Eng 122(12):676–682CrossRefGoogle Scholar
  14. Biron PM, Richer A, Kirkbride AD, Roy AG, Han S (2002) Spatial patterns of water surface topography at a river confluence. Earth Surf Process Landf 27:913–928CrossRefGoogle Scholar
  15. Boyer C, Roy AG, Best JL (2006) Dynamics of a river channel confluence with discordant beds: flow turbulence, bed load sediment transport, and bed morphology. J Geophys Res. CrossRefGoogle Scholar
  16. Brice JC (1954) Channel patterns and terraces of the Loup River in Nebraska, US Geol Survey Prof. Paper, 422-DGoogle Scholar
  17. Bristow CS, Best JL, Roy AG (1993) Morphology and facies models of channel confluences. In: Tomas JP (ed) Alluvial sedimentation. Special Publications of the International Association of Sedimentologists, vol 17, pp 91–100Google Scholar
  18. Chakraborty S, Datta K (2013) Causes and consequences of channel changes—a spatio-temporal analysis using remote sensing and GIS— Jaldhaka-Diana River System (Lower Course). J Environ Earth Sci 3:13Google Scholar
  19. Chakraborty S, Mukhopadhyay S (2014) A comparative study on the nature of channel confluence dynamics in the lower Jaldhaka River system, West Bengal, India. Int J Geol Earth Environ Sci 4(2):87–97Google Scholar
  20. Chakraborty S, Mukhopadhyay S (2015) River bank erosion and channel width adjustments across a meandering channel of North Bengal, India. Earth Sci India 8(3):61–78CrossRefGoogle Scholar
  21. Chanson H (2004) The hydraulics of open channel flow: an introduction: basic principles, sediment motion, hydraulic modelling, design of hydraulic structures, 2nd edn. Elsevier, AmsterdamGoogle Scholar
  22. Chorley RJ, Schumm SA, Sugden DE (1984) Geomorphology. Methuen, London and New YorkGoogle Scholar
  23. Church M (1983) Pattern of instability in a wandering gravel bed channel. In: Colinson JD, Lewin J (eds) Modern and ancient fluvial systems, vol 6. Blackwell, Special publication of the International Association of Sedimentologists, Oxford, pp 169–180CrossRefGoogle Scholar
  24. Church M (2006) Bed material transport and the morphology of alluvial river channels. Annu Rev Earth Planet Sci 34:325–354CrossRefGoogle Scholar
  25. Constantinescu G, Miyawaki S, Rhoads B, Sukhodolov A (2012) Numerical analysis of the effect of momentum ratio on the dynamics and sediment-entrainment capacity of coherent flow structures at a stream confluence. J Geophys Res 117:1–21CrossRefGoogle Scholar
  26. Das AK, Sah RK, Hazarika N (2012) Bankline change and the facets of riverine hazards in the floodplain of Subansiri–Ranganadi Doab, Brahmaputra Valley, India. Nat Hazards 64:1015–1028. CrossRefGoogle Scholar
  27. De Serres B, Roy AG, Biron P, Best JL (1999) Three-dimensional flow structure at a river channel confluence with discordant beds. Geomorphology 26:313–335CrossRefGoogle Scholar
  28. Deb M, Ferreira C (2015) Planform channel dynamics and bank migration hazard assessment of a highly sinuous river in the north-eastern zone of Bangladesh. Environ Earth Sci 73:6613–6623. CrossRefGoogle Scholar
  29. Debnath J, Das (Pan) N, Ahmed I, Bhowmik M (2017) Channel migration and its impact on land use/land cover using RS and GIS: a study on Khowai River of Tripura, North-East India. Egypt J Remote Sens Space Sci 20(2):197–210. CrossRefGoogle Scholar
  30. Dixon SJ, Sambrook Smith GH, Best JL, Nicholas AP, Bull JM et al (2018) The planform mobility of river channel confluences: insights from analysis of remotely sensed imagery. Earth Sci Rev 176:1–18CrossRefGoogle Scholar
  31. El Bastawesy M (2014) The geomorphological and hydrogeological evidences for a Holocene deluge in Arabia. Arab J Geosci 8(5):2577–2586. CrossRefGoogle Scholar
  32. Friedkin JF (1945) A laboratory study of the meandering of alluvial rivers. United States Waterways Experimental Station, VicksburgGoogle Scholar
  33. Fuller IC, Large ARG, Milan DJ (2003) Quantifying channel development and sediment transfer following chute cut-off in a wandering gravel-bed river. Geomorphology 54:307–323CrossRefGoogle Scholar
  34. Ghobadian R, Bajestan MS (2007) Investigation of sediment patterns at river confluence. J Appl Sci 7:1372–1380CrossRefGoogle Scholar
  35. Greated CA (1968) Supercritical flow through a junction. Houille Blanche 23(8):693–696CrossRefGoogle Scholar
  36. Gualtieri C, Ianniruberto M, Filizola N, Santos RV, Endreny T, (2017) Hydraulic complexity at a large river confluence in the Amazon Basin. Ecohydrology. CrossRefGoogle Scholar
  37. Gualtieri C, Filizola N, de Oliveira M, Santos AM, Ianniruberto M (2018) A field study of the confluence between Negro and Solimoes Rivers. Part 1: hydrodynamics and sediment transport. C R Geosci, (Special Issue “Rivers of the Andes and the Amazon Basin: Deciphering global change from the hydroclimatic variability in the critical zone”), 350 (1–2) 31–42CrossRefGoogle Scholar
  38. Hager WH (1995) Experiments to supercritical junction flow. Exp Fluids 18(6):429–437CrossRefGoogle Scholar
  39. Harmar OP, Clifford NJ (2006) Planform dynamics of the Lower Mississippi River. Earth Surf Process Landf 31:825–843CrossRefGoogle Scholar
  40. Hazarika N, Das AK, Borah SB (2015) Assessing land-use changes driven by river dynamics in chronically flood affected Upper Brahmaputra plains, India, using RS-GIS techniques. Egypt J Remote Sens Space Sci 18(1):107–118Google Scholar
  41. Hogan DL, Bird SA, Hassan MA (1998) Spatial and temporal evolution of small coastal gravel-bed streams: influence of forest management on channel morphology and fish habitats. In: Klingeman PC, Beschta RL, Komar PD, Bradley JD (eds) Gravel-bed rivers in the environment. Water Resources Publications, Littleton, pp 365–392Google Scholar
  42. Ianniruberto M, Trevethan M, Pinheiro A, Andrade JF, Dantas E, Filizola N, Santos A, Gualtieri C (2018) A field study of the confluence between Negro and Solimões Rivers. Part 2: River bed morphology and stratigraphy. C R Geosci, (Special Issue “Rivers of the Andes and the Amazon Basin: Deciphering global change from the hydroclimatic variability in the critical zone”) 350, 1–2, pp 43–54. CrossRefGoogle Scholar
  43. Kenworthy ST, Rhoads BL (1995) Hydrologic control of spatial patterns of suspended sediment concentration at a stream confluence. J Hydrol 168:251–263. CrossRefGoogle Scholar
  44. Knighton D (1984) Fluvial forms and processes: a new perspective. Arnold, London, p 383Google Scholar
  45. Kummu M, Lu XX, Rasphone A, Sarkkula J, Koponen J (2008) Riverbank changes along the Mekong River: remote sensing detection in the Vientiane–Nong Khai area. Quat Int 186:100–112CrossRefGoogle Scholar
  46. Leite RM, Blanckaert K, Roy AG, Schleiss AJ (2012) Flow and sediment dynamics in channel confluences. J Geophys Res Earth surf 117(F01035):1–19Google Scholar
  47. Leopold LB, Wolman MG, Miller JP (1964) Fluvial processes in geomorphology. Freeman, San Francisco, p 522Google Scholar
  48. Mackayj R (1966) The mixing of the waters of the Laird and Great Bear Rivers with those of the Mackenzie. Geogr Bull Can 8:166–173Google Scholar
  49. Mackayj R (1970) Lateral mixing of the Laird and Mackenzie Rivers downstream from their confluence. Can J Earth Sci 7:111–124CrossRefGoogle Scholar
  50. Madej MA, Weaver WE, Hagans DK (1994) Analysis of bank erosion on the Merced River, Yosemite Valley, Yosemite National Park, California, USA. Environ Manag 18(2):235–250CrossRefGoogle Scholar
  51. Majumdar S, Das (Pan) N (2014) Spatio-temporal shift of right bank of the Gumti River, Amarpur Town, Tripura and its impact. In: Singh M et al. (eds) Landscape ecology and water management: Proceedings of IGU Rohtak Conference, Advances in geographical and environmental sciences. Springer, TokyoGoogle Scholar
  52. Martín-Vide JP, Plana-Casado A, Sambola A, Capapé S (2015) Bed load transport in a river confluence. Geomorphology 250:15–28CrossRefGoogle Scholar
  53. Mathier L, Roy AG, Pare JP (1989) The effect of slope gradient and length on the parameters of a sediment transport equation for sheet wash. Catena 16(6):545–558. CrossRefGoogle Scholar
  54. McLelland SJ, Ashworth PJ, Best JL (1996) The origin and downstream development of coherent flow structures at channel junctions. In: Ashworth PJ, Bennett SJ, Best JL, McLelland SJ (eds) Coherent flow structures in open channels. Chichester, JohnWiley & Sons, pp 459–490Google Scholar
  55. Merritt DM, Wohl EE (2003) Downstream hydraulic geometry and channel adjustment during a flood along an ephemeral, arid region drainage. Geomorphology 52:165–180CrossRefGoogle Scholar
  56. Miller JP (1958) High mountain streams: effects of geology on channel characteristics and bed materials. In: New Mexico Bureau of Mines Mineral Resources. New Mexico Institute of Mining and Technology Socorro, New Mexico, (Memoir 4)Google Scholar
  57. Morisawa M (1985) Streams: their dynamics and morphology. McGraw Hill: New York p 91Google Scholar
  58. Mosley MP (1976) An experimental study of channel confluences. J Geol 84:535–562CrossRefGoogle Scholar
  59. Old GH, Lawler DM, Snorrason A (2005) Flow and sediment dynamics of a glacial outburst flood from the Skaftá system in southern Iceland. Earth Surf Process Landf 30:1441–1460CrossRefGoogle Scholar
  60. Ollero A (2010) Channel changes and floodplain management in meandering middle Ebro River, Spain. Geomorphology 117:247–260CrossRefGoogle Scholar
  61. Parsons DR, Best JL, Lane SN, Orfeo O, Hardy RJ, Kostaschuk R (2007) Form roughness and the absence of secondary flow in a large confluence–diffluence, Rio Paraná, Argentina. Earth Surf Process Landf 32:155–162CrossRefGoogle Scholar
  62. Petts GE, Amoros C (1984) Fluvial hydrosystems. Chapman and Hall, London, p 322Google Scholar
  63. Pizzuto JE (1992) The morphology of graded gravel rivers: a network perspective. Geomorphology 5:457–474CrossRefGoogle Scholar
  64. Platts WS, Armour C, Booth GD, Bryant M, Bufford JL, Cuplin P, Jensen S et al., (1987) Methods for evaluating riparian habitats with applications to management. Intermountain Research Station. General Technical Report INT-221, pp 177Google Scholar
  65. Porterfield G (1972) Computation of fluvial-sediment discharge. Techniques of water resources investigations of the United States Geological Survey, Book 3. US Geological SurveyGoogle Scholar
  66. Powell DM (1998) Patterns and processes of sediment sorting in gravel-bed rivers. Prog Phys Geogr 22(1):1–32CrossRefGoogle Scholar
  67. Rhoads BL, Kenworthy ST (1995) Flow structure at an asymmetrical stream confluence. Geomorphology 11:273–293.;(94)00069-4 CrossRefGoogle Scholar
  68. Rhoads BL, Kenworthy ST (1998) Time-averaged flow structure in the central region of a stream confluence. Earth Surf Process Landf 23(2):171–191. CrossRefGoogle Scholar
  69. Rhoads BL, Sukhodolov A (2001) Field investigation of three dimensional flow structures at stream confluences: part I. Thermal mixing and time-averaged velocities. Water Resour Res 37:2393–2410CrossRefGoogle Scholar
  70. Rhoads BL, Sukhodolov A (2004) Spatial and temporal structure of shear-layer turbulence at a stream confluence. Water Resour Res 40:2393–2410CrossRefGoogle Scholar
  71. Ribeiro ML, Blanckaert K, Roy AG, Schleiss AJ (2012) Flow and sediment dynamics in channel confluences. J Geophys Res 117(1):F01035. CrossRefGoogle Scholar
  72. Roy A, Bergeron N (1990) Flow and particle paths at a natural river confluence with coarse bed material. Geomorphology 3(2):99–112CrossRefGoogle Scholar
  73. Roy N, Sinha R (2007) Understanding confluence dynamics in the alluvial Ganga–Ramganga valley, India: an integrated approach using geomorphology and hydrology. Geomorphology 92:182–197CrossRefGoogle Scholar
  74. Roy AG, Roy R, Bergeron N (1988) Hydraulic geometry and changes in flow velocity at a river confluence with coarse bed material. Earth Surf Process Landf 13(7):583–598CrossRefGoogle Scholar
  75. Schumm SA (1963) Sinuosity of alluvial rivers on the Great Plains. Bull Geol Soc Am 74:1089–1100CrossRefGoogle Scholar
  76. Simmons CE (1993) Sediment characteristics of North Carolina streams, 1970–79. US Geological Survey, Water Supply Paper 2384. p 84Google Scholar
  77. Small RJ (1973) Braiding terraces in the Val D’Herens, Switzerland. Geography 58:129–135Google Scholar
  78. Stevaux JC, Franco AA, Etchebehere de Carlos ML, Fujita RH (2009) Flow structure and dynamics in large tropical river confluence: example of the Ivai and Parana Rivers, southern Brazil. Geosciencias 28(1):5–13Google Scholar
  79. Sukhodolov AN, Rhoads BL (2001) Field investigation of three dimensional flow structure at stream confluences: 2. Turbulence. Water Resour Res 37:2411–2424. CrossRefGoogle Scholar
  80. Szupiany RN, Amsler ML, Parsons DR, Best JL (2009) Morphology, flow structure, and suspended bed sediment transport at two large braid-bar confluences. Water Resour Res 45(5):1–19CrossRefGoogle Scholar
  81. Szupiany RN, Amsler ML, Hernandez J, Parsons DR, Best JL et al (2012) Flow fields, bed shear stresses, and suspended bed sediment dynamics in bifurcations of a large river. Water Resour Res 48:W11515. CrossRefGoogle Scholar
  82. Talukdar S, Pal S (2017) Impact of dam on inundation regime of flood plain wetland of punarbhaba river basin of barind tract of Indo-Bangladesh. Int Soil Water Conserv Res 5(2):109–121. CrossRefGoogle Scholar
  83. Thakur PK, Laha C, Aggarwal SP (2012) River bank erosion hazard study of river Ganga, upstream of Farakka barrage using remote sensing and GIS. Nat Hazards 61:967–987CrossRefGoogle Scholar
  84. White ID, Mottershead DN, Harrison SJ (1992) Environmental systems. An introductory text, 2nd edn. Chapman & Hall, LondonGoogle Scholar
  85. Winterbottom SJ (2000) Medium and short-term channel planform changes on the Rivers Tay and Tummel, Scotland. Geomorphology 34(3–4):195–208CrossRefGoogle Scholar
  86. Wohl EE, Pearthree PP (1991) Debris flows as geomorphic agents in the Huachuca Mountains of southeastern Arizona. Geomorphology 4:273–292CrossRefGoogle Scholar
  87. Woodward J, Foster I (1997) Erosion and suspended sediment transfer in river catchments: environmental controls, processes and problems. Geography 82(4):353–376Google Scholar
  88. Wuppukondur A (2018) Review of flow hydrodynamics and sediment transport at open channel confluences. Civil Eng Res J 5(3):555664. CrossRefGoogle Scholar
  89. Wuppukondur A, Chandra V (2017) Methods to control bed erosion at 90° river confluence: an experimental study. Int J River Basin Manag. CrossRefGoogle Scholar
  90. Yang CT, Stall JB (1974) Unit stream power for sediment transport in natural rivers. University of Illinois Water Resources Center Research Report, No. 88, p 38Google Scholar
  91. Yepez SP, Laraque A, Gualtieri C, Christophoul F, Marchan C, Castellanos B, Azocar JM, Lopez JL, Alfonso J (2018) Morphodynamic change analysis of bedforms in the Lower Orinoco River, Venezuela. Proc IAHS, 377, 41–50. CrossRefGoogle Scholar

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© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Jatan Debnath
    • 1
    Email author
  • Nibedita Das (Pan)
    • 1
  • Rakhal Sharma
    • 1
  • Istak Ahmed
    • 1
  1. 1.Department of Geography and Disaster ManagementTripura UniversityAgartalaIndia

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