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Fortnightly Changes in Water Transport Direction Across the Mouth of a Narrow Estuary

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This research investigates the dynamics of the axial tidal flow and residual circulation at the lower Guadiana Estuary, south Portugal, a narrow mesotidal estuary with low freshwater inputs. Current data were collected near the deepest part of the channel for 21 months and across the channel during two (spring and neap) tidal cycles. Results indicate that at the deep channel, depth-averaged currents are stronger and longer during the ebb at spring and during the flood at neap, resulting in opposite water transport directions at a fortnightly time scale. The net water transport across the entire channel is up-estuary at spring and down-estuary at neap, i.e., opposite to the one at the deep channel. At spring tide, when the estuary is considered to be well mixed, the observed pattern of circulation (outflow in the deep channel, inflow over the shoals) results from the combination of the Stokes transport and compensating return flow, which varies laterally with the bathymetry. At neap tide (in particular for those of lowest amplitude each month), inflows at the deep channel are consistently associated with the development of gravitational circulation. Comparisons with previous studies suggest that the baroclinic pressure gradient (rather than internal tidal asymmetries) is the main driver of the residual water transport. Our observations also indicate that the flushing out of the water accumulated up-estuary (at spring) may also produce strong unidirectional barotropic outflow across the entire channel around neap tide.

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References

  • Aubrey, D.G., and P.E. Speer. 1985. A study of non-linear tidal propagation in shallow inlet/estuarine systems: Part I. Observations. Estuarine. Coastal and Shelf Science 21: 185–205.

    Article  Google Scholar 

  • Becherer, J., G. Burchard, G. Floser, V. Mohrholz, and L. Umlauf. 2011. Evidence of tidal straining in well-mixed channel flow from micro-structure observations. Geophysical Research Letters 38: L17611.

    Article  Google Scholar 

  • Burchard, H., G. Flöser, J.V. Staneva, T.H. Badewien, and R. Riethmüller. 2008. Impact of density gradients on net sediment transport into the Wadden Sea. Journal of Physical Oceanography 38: 566–587.

    Article  Google Scholar 

  • Burchard, H., R.D. Hetland, E. Schulz, and H.M. Schuttelaars. 2011. Drivers of residual estuarine circulation in tidally energetic estuaries: Straight and irrotational channels with parabolic cross section. Journal of Physical Oceanography 41: 548–570.

    Article  Google Scholar 

  • Cáceres, M., A. Valle-Levinson, and L. Atkinson. 2003. Observations of cross-channel structure of flow in an energetic tidal channel. Journal of Geophysical Research 108: 3114.

    Article  Google Scholar 

  • Cheng, P., A. Valle-Levinson, and H.E. de Swart. 2010. Residual currents induced by asymmetric tidal mixing in weakly stratified narrow estuaries. Journal of Physical Oceanography 40: 2135–2147.

    Article  Google Scholar 

  • Cheng, P., A. Valle-Levinson, and H.E. de Swart. 2011. A numerical study of residual circulation induced by asymmetric tidal mixing in tidally dominated estuaries. Journal of Geophysical Research 116: C01017.

    Article  Google Scholar 

  • Dale, A.W., and R. Prego. 2003. Tidal and seasonal nutrient dynamics and budget of the Chupa Estuary, White Sea (Russia). Estuarine, Coastal and Shelf Science 56: 377–389.

    Article  CAS  Google Scholar 

  • de Jonge, V.N. 1992. Tidal flow and residual flow in the Ems estuary. Estuarine, Coastal and Shelf Science 34: 1–22.

    Article  Google Scholar 

  • Gao, L., D.-J. Li, and P.-X. Ding. 2008. Nutrient budgets averaged over tidal cycles off the Changjiang (Yangtze River) Estuary. Estuarine, Coastal and Shelf Science 77: 331–336.

    Article  Google Scholar 

  • Gardner, L.R., and B. Kjerfve. 2006. Tidal fluxes of nutrients and suspended sediments at the North Inlet–Winyah Bay National Estuarine Research Reserve. Estuarine, Coastal and Shelf Science 70: 682–692.

    Article  Google Scholar 

  • Garel, E., and Ó. Ferreira. 2011. Monitoring estuaries using non-permanent stations: practical aspects and data examples. Ocean Dynamics 61: 891–902.

    Article  Google Scholar 

  • Garel, E., L. Pinto, A. Santos, and Ó. Ferreira. 2009a. Tidal and river discharge forcing upon water and sediment circulation at a rock-bound estuary (Guadiana estuary, Portugal). Estuarine, Coastal and Shelf Science 84: 269–281.

    Article  CAS  Google Scholar 

  • Garel, E., S. Nunes, J.M. Neto, R. Fernandes, R. Neves, J.C. Marques, and Ó. Ferreira. 2009b. The autonomous Simpatico system for real-time continuous water-quality and current velocity monitoring: Examples of application in three Portuguese estuaries. Geo-Marine Letters 29: 331–341.

    Article  CAS  Google Scholar 

  • Haas, L.W. 1977. The effect of the spring–neap tidal cycle on the vertical salinity structure of the James, York and Rappahannock Rivers, Virginia, USA. Estuarine and Coastal Marine Science 5: 485–496.

    Article  Google Scholar 

  • Hansen, D.V., and M.J. Rattray. 1965. Gravitational circulation in straits and estuaries. Journal of Marine Research 23: 104–122.

    Google Scholar 

  • Hidrografico, I. 1990. Roteiro da Costa de Portugal, 504. Lisboa: Instituto Hidrografico.

    Google Scholar 

  • Jay, D.A., and J.D. Musiak. 1996. Internal tide asymmetry in channel flows: Origins and consequences. In Mixing in estuaries and coastal seas, coastal and estuarine studies, ed. C.B. Pattiaratchi, 211–249. Washington DC: American Geophysical Union.

    Chapter  Google Scholar 

  • Jay, D.A., and J.D. Smith. 1990. Residual circulation in shallow estuaries 2. Weakly stratified and partially mixed, narrow estuaries. Journal of Geophysical Research 95: 733–748.

    Article  Google Scholar 

  • Jiang, W., and S. Feng. 2011. Analytical solution for the tidally induced Lagrangian residual current in a narrow bay. Ocean Dynamics 61: 543–558.

    Article  Google Scholar 

  • Kjerfve, B. 1975. Velocity averaging in estuaries characterized by a large tidal range to depth ratio. Estuarine and Coastal Marine Science 3: 311–323.

    Article  Google Scholar 

  • Kjerfve, B., and J.A. Proehl. 1979. Velocity variability in a cross-section of a well-mixed estuary. Journal of Marine Research 37: 409–418.

    Google Scholar 

  • Lerczak, J.A., and R.W. Geyer. 2004. Modeling the lateral circulation in straight, stratified estuaries. Journal of Physical Oceanography 34: 1410–1428.

    Article  Google Scholar 

  • Li, C., and J. O’Donnell. 1997. Tidally driven residual circulation in shallow estuaries with lateral depth variation. Journal of Geophysical Research 102: 27915–27929.

    Article  Google Scholar 

  • Li, C., A. Valle-Levinson, K.C. Wong, and K.M.M. Lwiza. 1998. Separating baroclinic flow from tidally induced flow in estuaries. Journal of Geophysical Research 103: 10405–10417.

    Article  Google Scholar 

  • Li, C.Y., and J. O'Donnell. 2005. The effect of channel length on the residual circulation in tidally dominated channels. Journal of Physical Oceanography 35: 1826–1840.

    Article  Google Scholar 

  • Li, M., and L. Zhong. 2009. Flood–ebb and spring–neap variations of mixing, stratification and circulation in Chesapeake Bay. Continental Shelf Research 29: 4–14.

    Article  Google Scholar 

  • Lobo, J., F. Plaza, R. Gonzáles, J. Dias, V. Kapsimalis, I. Mendes and V.D.d. Rio. 2004. Estimations of bedload sediment transport in the Guadiana Estuary (SW Iberian Peninsula) during low river discharge periods. Journal of Coastal Research 12–26.

  • Lwiza, K.M.M., D.G. Bowers, and J.H. Simpson. 1991. Residual and tidal flow at a tidal mixing front in the North Sea. Continental Shelf Research 11: 1379–1395.

    Article  Google Scholar 

  • Mantovanelli, A., E. Marone, E.T. Silva, L.F. Lautert, M.S. Klingenfuss, V.P.J. Prata, M.A. Noernberg, B.A. Knoppers, and R.J. Angulo. 2004. Combined tidal velocity and duration asymmetries as a determinant of water transport and residual flow in Paranaguá Bay estuary. Estuarine, Coastal and Shelf Science 59: 523–537.

    Article  CAS  Google Scholar 

  • Nunes, R.A., and G.W. Lennon. 1987. Episodic stratification and gravity currents in a marine environment of modulated turbulence. Journal of Geophysical Research 92: 5465–5480.

    Article  Google Scholar 

  • Nunes Vaz, R.A., G.W. Lennon, and J.R. de Silva Samarasinghe. 1989. The negative role of turbulence in estuarine mass transport. Estuarine, Coastal and Shelf Science 28: 361–377.

    Article  CAS  Google Scholar 

  • Pawlowicz, R., B. Beardsley, and S. Lentz. 2002. Classical tidal harmonic analysis including error estimates in MATLAB using T_TIDE. Computers and Geosciences 28: 929–937.

    Article  Google Scholar 

  • Pritchard, D.W. 1956. The dynamic structure of a coastal plain estuary. Journal of Marine Research 15: 33–42.

    Google Scholar 

  • Pritchard, D.W., 1960. Lectures on estuarine oceanography. J. Hopkins University, 154 pp.

  • Scully, M.E., and C.T. Friedrichs. 2007. The importance of tidal and lateral asymmetries in stratification to residual circulation in partially mixed estuaries. Journal of Physical Oceanography 37: 1496–1511.

    Article  Google Scholar 

  • Silva, A.J.d., S. Lino, A.I. Santos and A. Oliveira, 2003. Near bottom sediment dynamics in the Guadiana Estuary. In: Proceedings 4th Symposium on the Iberian Atlantic Margin, Thalassas, pp. 180–182.

  • Simons, R.D., S.G. Monismith, F.J. Saucier, L.E. Johnson, and G. Winkler. 2010. Modelling stratification and baroclinic flow in the estuarine transition zone of the St. Lawrence estuary. Atmosphere-Ocean 48: 132–146.

    Article  Google Scholar 

  • Simpson, J.H., J. Brown, J. Matthews, and G. Allen. 1990. Tidal straining, density currents, and stirring in the control of estuarine stratification. Estuaries 13: 125–132.

    Article  Google Scholar 

  • Simpson, J.H., E. Williams, L.H. Brasseur, and J.M. Brubaker. 2005. The impact of tidal straining on the cycle of turbulence in a partially stratified estuary. Continental Shelf Research 25: 51–64.

    Article  Google Scholar 

  • Speer, P.E., and D.G. Aubrey. 1985. A study of non-linear tidal propagation in shallow inlet/estuarine systems: Part II. Theory. Estuarine, Coastal and Shelf Science 21: 207–224.

    Article  Google Scholar 

  • Stacey, M.T., J.R. Burau, and S.G. Monismith. 2001. Creation of residual flows in a partially stratified estuary. Journal of Geophysical Research 106: 17013–17043.

    Article  Google Scholar 

  • Uncles, R.J. 2002. Estuarine physical processes eesearch: Some recent studies and progress. Estuarine, Coastal and Shelf Science 55: 829–856.

    Article  Google Scholar 

  • Uncles, R.J., R.C.A. Elliott, and S.A. Weston. 1985. Observed fluxes of water, salt and suspended sediment in a partly mixed estuary. Estuarine, Coastal and Shelf Science 20: 147–167.

    Article  CAS  Google Scholar 

  • Uncles, R.J., and J.A. Stephens. 1990. The structure of vertical current profiles in a macrotidal, partly-mixed estuary. Estuaries 13: 349–361.

    Article  Google Scholar 

  • Valle-Levinson, A., C. Reyes, and R. Sanay. 2003. Effects of bathymetry, friction, and rotation on estuary–ocean exchange. Journal of Physical Oceanography 33: 2375–2393.

    Article  Google Scholar 

  • Valle-Levinson, A., G.G. Velasco, A. Trasviña, A.J. Souza, R. Durazo, and A.J. Mehta. 2009. Residual exchange flows in subtropical estuaries. Estuaries and Coasts 32: 54–67.

    Article  Google Scholar 

  • Waterhouse, A., and A. Valle-Levinson. 2010. Transverse structure of subtidal flow in a weakly stratified subtropical tidal inlet. Continental Shelf Research 30: 281–292.

    Article  Google Scholar 

  • Wei, H., D. Hainbucher, T. Pohlmann, S. Feng, and J. Suendermann. 2004. Tidal-induced Lagrangian and Eulerian mean circulation in the Bohai Sea. Journal of Marine Systems 44: 141–151.

    Article  Google Scholar 

  • Whiting, G.J., and D.L. Childers. 1989. Subtidal advective water flux as a potentially important nutrient input to southeastern U.S.A. saltmarsh estuaries. Estuarine. Coastal and Shelf Science 28: 417–431.

    Article  CAS  Google Scholar 

  • Winant, C.D. 2008. Three dimensional residual tidal circulation in an elongated, rotating, basin. Journal of Physical Oceanography 38: 1278–1295.

    Article  Google Scholar 

  • Winant, C.D. 2010. Two-layer circulation in a frictional, rotating basin. Journal of Physical Oceanography 40: 1390–1404.

    Article  Google Scholar 

  • Winant, C.D., and G. Gutiérrez de Velasco. 2003. Tidal dynamics and residual circulation in a well-mixed inverse estuary. Journal of Physical Oceanography 33: 1365–1379.

    Article  Google Scholar 

  • Wong, K.C. 1994. On the nature of transverse variability in a coastal plain estuary. Journal of Geophysical Research 99: 14209–14222.

    Article  Google Scholar 

  • Zimmerman, J. 1979. On the Euler–Lagrange transformation and the Stokes’ drift in the presence of oscillatory and residual currents. Deep Sea Research 26A: 505–520.

    Google Scholar 

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Acknowledgments

Centre for Science (Centro Ciência Viva) from Tavira is acknowledged for the atmospheric pressure data. Thanks are extended to A. Pacheco for assistance in collecting data. E. Garel benefited from FCT (Fundação para a Ciência e Tecnologia, Portuguese National Board of Scientific Research) grants SFRH/BPD/34475/2005. The bottom-mounted current-meter is part of a monitoring station (Simpatico system) that was acquired through a FCT grant for the re-equipment of scientific institutions (Reeq/484/MAR/2005). We are also grateful to two anonymous reviewers who have contributed significantly to improve the quality of the original manuscript.

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  1. CIMA (Centre for Marine and Environmental Research), Universidade do Algarve, Edifício 7, Campus de Gambelas, 8005-139, Faro, Portugal

    Erwan Garel & Óscar Ferreira

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  1. Erwan Garel
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Correspondence to Erwan Garel.

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Garel, E., Ferreira, Ó. Fortnightly Changes in Water Transport Direction Across the Mouth of a Narrow Estuary. Estuaries and Coasts 36, 286–299 (2013). https://doi.org/10.1007/s12237-012-9566-z

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  • DOI: https://doi.org/10.1007/s12237-012-9566-z

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