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Estuaries and Coasts

, Volume 30, Issue 1, pp 113–126 | Cite as

Spatial structure of hydrography and flow in a Chilean fjord, Estuario Reloncaví

  • Arnoldo Valle-Levinson
  • Nandita Sarkar
  • Rosario Sanay
  • Doris Soto
  • Jorge León
Article

Abstract

Underway current velocity profiles were combined with temperature and salinity profiles at fixed stations to describe tidal and subtidal flow patterns in the middle of the northernmost Chilean fjord, Estuario Reloncaví. This is the first study involving current velocity measurements in this fjord. Reloncaví fjord is 55 km long, 2 km wide, and on average is 170 m deep. Measurements concentrated around a marked bend of the coastline, where an 8-km along-fjord transect was sampled during a semidiurnal tidal cycle in March 2002 and a 2-km cross-fjord transect was occupied, also during a semidiurnal cycle, in May 2004. The fjord hydrography showed a relatively thin (<5 m deep), continuously stratified, buoyant layer with stratification values >4 kg m−3 per meter of depth. Below this thin layer, the water was relatively homogeneous. Semidiurnal tidal currents had low amplitudes (<10 cm s−1) that allowed the persistence of a surface front throughout the tidal cycle. The front oscillated with a period of ca. 2.5 h and showed excursions of 2 km. The front oscillations could have been produced by a lateral seiche that corresponds to the natural period of oscillation across the fjord. This front could have also caused large (2 h) phase lags in the semidiurnal tidal currents, from one end of the transect to the other, within the buoyant layer. Tidal phases were relatively uniform underneath this buoyant layer. Subtidal flows showed a 3-layer pattern consisting of a surface layer (8 m thick, of 5 cm s−1 surface outflow), an intermediate layer (70 m thick, of 3 cm s−1 net inflow), and a bottom layer (below 80 m depth, of 3 cm s−1 net outflow). The surface outflow and, to a certain extent, the inflow layer were related to the buoyant water interacting with the ambient oceanic water. The inflowing layer and the bottom outflow were attributed to nonlinear effects associated with a tidal wave that reflects at the fjord's head. The weak subtidal currents followed the morphology of the bend and caused downwelling on the inside and upwelling on the outside part of the bend.

Keywords

Tidal Current Acoustic Doppler Current Profiler Centrifugal Acceleration Form Drag Continental Shelf Research 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Literature Cited

  1. Bathurst, J. C., C. R. Thorne, andR. D. Hey. 1977. Direct measurements of secondary currents in river bends.Nature 269:504–506.CrossRefGoogle Scholar
  2. Cáceres, M., A. Valle-Levinson, andL. Atkinson. 2003. Observations of cross-channel structure of flow in an energetic tidal channel.Journal of Geophysical Research 108:3114, doi:10.1029/2001JC000968.CrossRefGoogle Scholar
  3. Cáceres, M., A. Valle-Levinson, H. H. Sepulveda, andK. Holderied. 2002. Transverse variability of flow and density in a Chilean fjord.Continental Shelf Research 22:1683–1698.CrossRefGoogle Scholar
  4. Chant, R. J. andR. E. Wilson. 1997. Secondary circulation in a highly stratified estuary.Journal of Geophysical Research 102: 23207–23215.CrossRefGoogle Scholar
  5. Edwards, K. A., P. MacCready, J. N. Moum, G. Pawlak, J. M. Klymak, andA. Perlin. 2004. Form drag and mixing due to tidal flow past a sharp point.Journal of Physical Oceanography 34:1297–1312.CrossRefGoogle Scholar
  6. Geyer, W. R. 1993. Three-dimensional tidal flow around headlands.Journal of Geophysical Research 98:955–966.CrossRefGoogle Scholar
  7. Geyer, W. R. andR. Signell. 1990. Measurements of tidal flow around a headland with a shipboard acoustic Doppler current profiler.Journal of Geophysical Research 95:3189–3197.CrossRefGoogle Scholar
  8. Ianniello, J. P. 1977. Tidally induced residual current in estuaries of constant breadth and depth.Journal of Marine Research 35:755–786.Google Scholar
  9. Ianniello, J. P. 1978. Tidally induced residual current in estuaries of variable breadth and depth.Journal of Physical Oceanography 9: 962–974.CrossRefGoogle Scholar
  10. Joyce, T. M. 1989. On in situ calibration of shipboard ADCPs.Journal of Atmospheric Oceanic Technology 6:169–172.CrossRefGoogle Scholar
  11. Lacy, J. andS. Monismith. 2001. Secondary currents in a curved, stratified estuarine channel.Journal of Geophysical Research 106: 31283–31302.CrossRefGoogle Scholar
  12. Lacy, J., M. Stacey, J. R. Burau, and S. Monismith. 2003. Interaction of lateral baroclinic forcing and turbulence in an estuary.Journal of Geophysical Research 108: doi:10.1029/2002JC001392.Google Scholar
  13. León, J. E. 2005. Influencia del caudal del Río Puelo sobre la salinidad y la concentración de oxígeno disuelto en el Estuario de Reloncaví, Llanquihue, Chile, M.S. Thesis. Universidad Austral de Chile, Valdivia, Chile.Google Scholar
  14. Lwiza, K. M. M., D. G. Bowers, andJ. H. Simpson. 1991. Residual and tidal flow at a tidal mixing front in the North Sea.Continental Shelf Research 11:1379–1395.CrossRefGoogle Scholar
  15. Malone, T. C., W. M. Kemp, H. W. Ducklow, W. R. Boynton, J. H. Tuttle, andR. B. Jonas. 1986. Lateral variation in the production and fate of phytoplankton in a partially stratified estuary.Marine Ecology Progress Series 32:149–160.CrossRefGoogle Scholar
  16. Milliman, J. D., C. Rutkowski, andM. Meybeck. 1995. River discharge to the sea. A global river index (GLORI). LOICZ Reports and Studies, Texel, The Netherlands.Google Scholar
  17. Niemeyer, H. andP. Cereceda. 1984. Hidrografia, p. 1–313.In I. G. Militar (ed.), Geografía de Chile, Volume VIII. Instituto Geografía de Chile, Santiago, Chile.Google Scholar
  18. Parker, B. B. 1991. The relative importance of the various nonlinear mechanisms in a wide range of tidal interactions (review) p. 237–268.In B. Parker (ed.), Tidal Hydrodynamics. John Wiley and Sons, New York.Google Scholar
  19. Seim, H., J. O. Blanton, andT. Gross. 2002. Direct stress measurements in a shallow, sinuous estuary.Continental Shelf Research 22:1565–1578.CrossRefGoogle Scholar
  20. Seim, H., andM. Gregg. 1997. The importance of aspiration and channel curvature in producing strong vertical mixing over a sill.Journal of Geophysical Research 102:3451–3472.CrossRefGoogle Scholar
  21. Signell, R., andW. R. Geyer. 1991. Transient eddy formation around headlands.Journal of Geophysical Research 96:2561–2575.CrossRefGoogle Scholar
  22. Soto, D., andF. Norambuena. 2004. Evaluation of salmon farming effects on marine systems in the inner seas of southern Chile: A large-scale mensurative experiment.Journal of Applied Ichthyology 20:493–501.CrossRefGoogle Scholar
  23. Souza, A. J., andJ. H. Simpson. 1996. The modification of tidal ellipses by the stratification in the Rhine ROFI.Continental Shelf Research 16:997–1007.CrossRefGoogle Scholar
  24. Stigebrandt, A. 1977. On the effect of barotropic current fluctuations on the two-layer transport capacity of a constriction.Journal of Physical Oceanography 7:118–122.CrossRefGoogle Scholar
  25. Svendsen, H., andR. O. R. Y. Thompson. 1978. Wind-driven circulation in a fjord.Journal of Physical Oceanography 8:705–712.CrossRefGoogle Scholar
  26. Thorne, C. R., andR. D. Hey. 1979. Direct measurements of secondary currents at a river inflexion point.Nature 280:226–228.CrossRefGoogle Scholar
  27. Valle-Levinson, A., andL. Atkinson. 1999. Spatial gradients in the flow over an estuarine channel.Estuaries 22:179–193.CrossRefGoogle Scholar
  28. Valle-Levinson, A., andJ. L. Blanco. 2004. Observations of wind influence on exchange flows in a strait of the Chilean Inland Sea.Journal of Marine Research 62:721–741.CrossRefGoogle Scholar

Copyright information

© Estuarine Research Federation 2007

Authors and Affiliations

  • Arnoldo Valle-Levinson
    • 1
  • Nandita Sarkar
    • 2
  • Rosario Sanay
    • 3
  • Doris Soto
    • 4
  • Jorge León
    • 4
  1. 1.Civil and Coastal EngineeringUniversity of FloridaGainesville
  2. 2.Center for Coastal Physical OceanographyOld Dominion UniversityNorfolk
  3. 3.Marine Science Program, Department of Geological SciencesUniversity of South CarolinaColumbia
  4. 4.Facultad de Pesquerías y OceanografíaUniversidad Austral de ChilePuerto MonttChile

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