Impacts of Relative Sea-level Rise on Evolution of Shallow Estuaries

  • Carl T. Friedrichs
  • David G. Aubrey
  • Paul E. Speer
Part of the Coastal and Estuarine Studies book series (COASTAL, volume 38)

Abstract

The present study investigates the impact of relative sea-level rise on tidal propagation in shallow, well-mixed estuaries. Distortion of the co-oscillating estuarine tide is a composite of two principal non-linear effects: frictional interaction between the tide and channel (reflected in the scale a/h, or ratio of tidal amplitude to mean channel depth) and intertidal storage on tidal flats and marshes (measured by Vs/Vc, or ratio of volume of intertidal storage to volume of channels at mean sea level). Estuarine hypsometry (distribution of estuary surface area with height) defines a/h and Vs/Vc, and indicates whether these parameters will increase or decrease with increasing water level. The potential impact of sea-level rise is investigated utilizing both one-dimensional numerical modeling and seasonal fluctuations in mean sea levels at six shallow estuaries along the U.S. Atlantic Coast. These fluctuations are used as analogues to interannual trends in mean sea level rise. Numerical results and analysis of tidal propagation at the selected estuaries indicate that in flood dominant estuaries having relatively constant bank slope (rectangular or trapezoidal cross-section), a/h and degree of tidal distortion decrease with increased sea level. In estuaries having highly curved bank slope, a/h and Vs/Vc increase in flood and ebb dominant systems, increasing the degree of distortion and reinforcing existing tidal asymmetries. These findings have implications for the evolution of shallow estuaries as global sea level rises (an anticipated consequence of increased atmospheric trace gas loading). Whether estuaries import or export increased amounts of sediments as global sea-level rises depends on local estuarine geometry. Some systems will infill faster as sea level rises, while some will flush more efficiently. These contrasting responses to mean sea-level rise mandate a careful assessment of how any individual estuary may respond to rising water levels.

Keywords

Dioxide Sedimentation Topo Flushing 

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Copyright information

© Springer-Verlag New York, Inc. 1990

Authors and Affiliations

  • Carl T. Friedrichs
    • 1
  • David G. Aubrey
    • 1
  • Paul E. Speer
    • 2
  1. 1.Woods Hole Oceanographic InstitutionWoods HoleUSA
  2. 2.Center for Naval AnalysesAlexandriaUSA

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