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Episodic sediment accumulation on Amazonian flood plains influenced by El Niño/Southern Oscillation

Abstract

Continental-scale rivers with a sandy bed sequester a significant proportion of their sediment load in flood plains. The spatial extent and depths of such deposits have been described1,2, and flood-plain accumulation has been determined at decadal timescales3,4,5, but it has not been possible to identify discrete events or to resolve deposition on near-annual timescales. Here we analyse 210Pb activity profiles from sediment cores taken in the pristine Beni and Mamore river basins, which together comprise 720,000 km2 of the Amazon basin, to investigate sediment accumulation patterns in the Andean–Amazonian foreland. We find that in most locations, sediment stratigraphy is dominated by discrete packages of sediments of uniform age, which are typically 20–80 cm thick, with system-wide recurrence intervals of about 8 yr, indicating relatively rare episodic deposition events. Ocean temperature and stream flow records link these episodic events to rapidly rising floods associated with La Niña events, which debouch extraordinary volumes of sediments from the Andes. We conclude that transient processes driven by the El Niño/Southern Oscillation cycle control the formation of the Bolivian flood plains and modulate downstream delivery of sediments as well as associated carbon, nutrients and pollutants to the Amazon main stem.

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Figure 1: The Beni and Mamore river flood plains within the Llanos, northern Bolivia.
Figure 2: Unsupported 210Pb activity profiles (circles) and clay abundance (crosses) from representative flood-plain cores.
Figure 3: Spatial distribution of Beni flood-plain accumulation rates, averaged for five distance ranges, with best exponential fit (r2 = 0.82).
Figure 4: Temporal distribution of fluvial processes.

References

  1. 1

    Kesel, R. H., Yodis, E. G. & McCraw, D. J. An approximation of the sediment budget of the lower Mississippi River prior to major human modification. Earth Surf. Process. Landforms 17, 711–722 (1992)

    ADS  Article  Google Scholar 

  2. 2

    Aslan, A. & Autin, W. J. Evolution of the Holocene Mississippi River floodplain, Ferriday, Louisiana: insights of the origin of fine-grained floodplains. J. Sedim. Res. 69, 800–815 (1999)

    Article  Google Scholar 

  3. 3

    Nicholas, A. P. & Walling, D. E. Investigating spatial patterns of medium-term overbank sedimentation on floodplains: a combined numerical modeling and radiocaesium-based approach. Geomorphology 19, 133–150 (1997)

    ADS  Article  Google Scholar 

  4. 4

    He, Q. & Walling, D. E. Use of fallout Pb-210 measurements to investigate longer-term rates and patterns of overbank sediment deposition on the floodplains of lowland rivers. Earth Surf. Process. Landforms 21, 141–154 (1996)

    ADS  CAS  Article  Google Scholar 

  5. 5

    Goodbred, S. L. Jr & Kuehl, S. A. Floodplain processes in the Bengal Basin and the storage of Ganges-Brahmaputra river sediment: an accretion study using Cs-137 and Pb-210 geochronology. Sediment. Geol. 121, 239–258 (1998)

    ADS  CAS  Article  Google Scholar 

  6. 6

    Mertes, L. A. K. Rates of flood-plain sedimentation on the central Amazon River. Geology 22, 171–174 (1994)

    ADS  Article  Google Scholar 

  7. 7

    Howard, A. D. in Lowland Floodplain Rivers: Geomorphological Perspectives (eds Carling, P. A. & Petts, G. E.) (Wiley and Sons, Chichester, UK, 1992)

    Google Scholar 

  8. 8

    Pizzuto, J. E. Sediment diffusion during overbank flows. Sedimentology 34, 301–317 (1987)

    ADS  Article  Google Scholar 

  9. 9

    James, C. S. Sediment transfer to overbank sections. J. Hydraul. Res. 23, 435–452 (1985)

    Article  Google Scholar 

  10. 10

    Dunne, T., Mertes, L. A. K., Meade, R. H., Richey, J. E. & Forsberg, B. R. Exchanges of sediment between the floodplain and channel of the Amazon River in Brazil. Geol. Soc. Am. Bull. 110, 450–467 (1998)

    ADS  Article  Google Scholar 

  11. 11

    Allison, M. A., Kuehl, S. A., Martin, T. C. & Hassan, A. Importance of flood-plain sedimentation for river sediment budgets and terrigenous input to the oceans: Insights from the Brahmaputra-Jamuna River. Geology 26, 175–178 (1998)

    ADS  Article  Google Scholar 

  12. 12

    Aalto, R. & Nittrouer, C. A. Application of fallout 210Pb geochronology to river-floodplain systems. Sediment. Geol. (submitted)

  13. 13

    Aalto, R. Geomorphic Form and Process of Mass Flux Within an Active Orogen: Denudation of the Bolivian Andes and Sediment Transport and Deposition Within the Channel-Floodplain Systems of the Amazonian Foreland. 365 Thesis, Univ. Washington (2002)

    Google Scholar 

  14. 14

    Aalto, R., Dunne, T. & Guyot, J. L. Geomorphic controls on Andean denudation rates. J. Geol. (in the press)

  15. 15

    Horton, B. K. & DeCelles, P. G. The modern foreland basin system adjacent to the Central Andes. Geology 25, 895–898 (1997)

    ADS  Article  Google Scholar 

  16. 16

    Baby, P., Rochat, P., Mascle, G. & Hérail, G. Neogene shortening contribution to crustal thickening in the back arc of the Central Andes. Geology 25, 883–886 (1997)

    ADS  Article  Google Scholar 

  17. 17

    Guyot, J. L. Hydrogéochimie des Fleuves de l'Amazonie Bolivienne, (Collection Études & Thèses, ORSTOM Ed.), Paris, (1993)

    Google Scholar 

  18. 18

    Aalto, R., Dunne, T., Maurice-Bourgoin, L., Guyot, J. L. & Nittrouer, C. A. Beni River morphology, migration, and sediment exchange between the river and its floodplain. Geol. Soc. Am. Bull. (submitted)

  19. 19

    Nie, Y., Suayah, I. B., Benninger, L. K. & Alperin, M. J. Modeling detailed sedimentary 210-Pb and fallout 239–240-Pu profiles to allow episodic events: an application to Chesapeake Bay. Limnol. Oceanogr. 46, 1425–1437 (2001)

    ADS  CAS  Article  Google Scholar 

  20. 20

    Aceituno, P. On the functioning of the Southern Oscillation in the South America Sector Part I: Surface climate. Mon. Weath. Rev. 116, 505–524 (1988)

    ADS  Article  Google Scholar 

  21. 21

    Maurice-Bourgoin, L., Ronchail, J., Vauchel, P., Aalto, R. & Guyot, J. L. Climate controls (ENSO) on the flooding of the Beni River, a large Andean tributary of the Amazon. EOS AGI Trans. Spring A-09895 (2003)

  22. 22

    Coelho, C. A. S., Uvo, C. B. & Ambrizzi, T. Exploring the impacts of the tropical Pacific SST on the precipitation patterns over South America during ENSO periods. Theor. Appl. Climatol. 71, 185–197 (2002)

    ADS  Article  Google Scholar 

  23. 23

    Ronchail, J. Variabilité pluviométrique en Bolivie lors des phases extrêmes de l'oscillation australe du Pacifique (1950–1993). Bull. Inst. Fr. Etud. Andines 27, 687–698 (1998)

    Google Scholar 

  24. 24

    Guyot, J. L., Jouanneau, J. M. & Wasson, J. G. Characterisation of river bed and suspended sediments in the Rio Madeira drainage basin (Bolivian Amazonia). J. Soc. Am. Earth Sci. 12, 401–410 (1999)

    Article  Google Scholar 

  25. 25

    Smith, N. D., Cross, T. A., Dufficy, J. P. & Clough, S. R. Anatomy of an avulsion. Sedimentology 36, 1–23 (1989)

    ADS  Article  Google Scholar 

  26. 26

    Horton, B. K., Hampton, B. A. & Waanders, G. L. Paleogene synorogenic sedimentation in the Altiplano plateau and implications for initial mountain building in the central Andes. Geol. Soc. Am. Bull. 113, 1387–1400 (2001)

    ADS  Article  Google Scholar 

  27. 27

    Slingerland, R. L. & Smith, N. D. Necessary conditions for a meandering river avulsion. Geology 26, 435–438 (1998)

    ADS  Article  Google Scholar 

  28. 28

    Mertes, L. A. K. Description and significance of the perirheic zone on inundated floodplains. Wat. Resour. Res. 33, 1749–1762 (1997)

    ADS  Article  Google Scholar 

  29. 29

    Richey, J. E., Melack, J. M., Aufdenkampe, A. K., Ballester, V. M. & Hess, L. L. Outgassing from Amazonian rivers and wetlands as a large tropical source of atmospheric CO2 . Nature 416, 617–620 (2002)

    ADS  CAS  Article  Google Scholar 

  30. 30

    Meyers, S. D., Thelin, E. & O'Brien, J. J. Reconstruction of monthly SST in the tropical Pacific Ocean during 1868–1993 using adaptive climate basis functions. Mon. Weath. Rev. 127, 1599–1612 (1999)

    ADS  Article  Google Scholar 

Download references

Acknowledgements

This work was supported by an NSF research grant, a NASA Earth Systems Science Graduate Fellowship to R.A., and by the research collaboration (HYBAM Project) between IRD, SENAMHI (Bolivia), and the Universidad Mayor de San Andres, Bolivia. Laboratory assistance was provided by J. Staly, K. Sauers, G. Smith, J. Nittrouer and C. Gardner. Suggestions from C. Paola and A. Aufdenkampe improved the manuscript.

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Correspondence to Rolf Aalto.

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Aalto, R., Maurice-Bourgoin, L., Dunne, T. et al. Episodic sediment accumulation on Amazonian flood plains influenced by El Niño/Southern Oscillation. Nature 425, 493–497 (2003). https://doi.org/10.1038/nature02002

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