Advertisement

Long Term Impacts of Jetties and Training Walls on Estuarine Hydraulics and Ecologies

  • Alexander F. NielsenEmail author
  • Angus D. Gordon
Chapter
Part of the Coastal Research Library book series (COASTALRL, volume 21)

Abstract

Data and theory show that the inlets of several large estuaries on Australia’s eastern seaboard that appeared to be stable within a range of entrance conditions are demonstrating unstable scouring modes and have been doing so for decades, if not centuries, since entrance jetties had been constructed. Jetties have increased the hydraulic conveyance of the entrance channels by removing sand bars and extraneous littoral currents that impeded ebb tide discharges. Field data comprising comprehensive water level monitoring in the bays, enabling the definition of tidal planes to a high resolution, have shown that the spring tidal ranges of these bays has been increasing steadily for decades with high tide planes rising and low tide planes falling. The field data have indicated that these changes show no signs of stabilizing and Escoffier analyses have indicated that it could take centuries for these inlets to reach new stable hydraulic regimes. Implications have included extensive scour in the entrance channels requiring channel erosion protection works, subsidence of road bridges, collapse of foreshores including buildings, sedimentation in the bays and on adjacent beaches and permanent changes to fringing marine ecologies and fisheries. Changes to the distribution of seagrass, saltmarsh and mangrove forests have been observed to coincide with and confirm the expectations of impacts on marine ecology that could derive from jetty construction. While jetties have improved flood conveyance significantly the increases in ebb tide velocities have resulted in navigational hazards for recreational boating.

Keywords

Tidal constituents Amplitude Phase Prism Inlet Equilibrium area Escoffier stability analysis Jetties Training walls Marine ecology 

References

  1. Brown EI (1928) Inlets on sandy coasts. ASCE Proc 54:505–553Google Scholar
  2. Bruun P (1978) Design of tidal inlets on littoral drift shores. Coastal Sediments ‘77. Proceedings 5th Symposium of the Waterway, Port, Coastal and Ocean Division of ASCE, Charleston, pp 927–945Google Scholar
  3. Burrell A (2012) Mapping changes of saltmarsh and mangrove vegetation communities in Wagonga Inlet, NSW South Coast Bachelor of Environmental Science (Honours), School of Earth & Environmental Science, University of Wollongong, 166ppGoogle Scholar
  4. Czerniak MT (1978) Inlet interaction and stability theory verification. Coastal Sediments ‘77. Proceedings 5th Symposium of the Waterway, Port, Coastal and Ocean Division of ASCE, Charleston, pp 754–773Google Scholar
  5. Dekker AG, Anstee JM, Brando VE (2003) Seagrass change assessment using satellite data for Wallis Lake, NSW. CSIRO Land and Water Technical Report 13/03 in pdf format at http://www.clw.csiro.au/publications/technical2003/
  6. Duchatel K, Williams R, Gordon AD, Nielsen AF (2014) Unintended long term environmental disturbances from estuary entrance breakwaters. Proceedings Environment Institute of Australia & New Zealand Annual Conference, HobartGoogle Scholar
  7. Escoffier FF (1940) The stability of tidal inlets. Shore Beach 8(4):114–115Google Scholar
  8. Gordon AD (1990) Coastal lagoon entrance dynamics. Proceedings 22nd Coastal Engineering Conference, ASCE, pp 2880–2893Google Scholar
  9. Henderson FM (1966) Open channel flow, Macmillan, New York, 522ppGoogle Scholar
  10. Jarrett JT (1976) Tidal prism – inlet area relationships. GITT Report 3, U.S. Army Coastal Engineering Research Centre, Ft Belvoir, 32ppGoogle Scholar
  11. Kailola PJ (1993) Fisheries research and development corporation (Australia) & Australia Bureau of Resource Sciences, Australian fisheries resources. Bureau of Resource Sciences and the Fisheries Research and Development Corporation, Canberra, 422ppGoogle Scholar
  12. Keulegan GH (1951) Tidal flow in entrances, water level fluctuations of basins in communication with seas. National Bureau of Standards Report No. 1146, 28ppGoogle Scholar
  13. Keulegan GH (1967) Tidal flow in entrances water-level fluctuations of basins in communication with seas. Tech Bull 14, U S Army Corps of Engineers, 89ppGoogle Scholar
  14. MHL (1994) NSW breakwaters – asset appraisal. Public Works Department State Projects Manly Hydraulics Laboratory Report MHL647, MayGoogle Scholar
  15. MHL (2001) Wagonga inlet processes study. NSW Dept. Public Works & Services, Manly Hydraulics Laboratory Report MHL1011, AprilGoogle Scholar
  16. Mota Oliviera IB (1970) Natural flushing ability in tidal inlets. Proceedings 12th Coastal Engineering Conference, ASCE, pp 1827–1845Google Scholar
  17. Nielsen AF, Gordon AD (1980) Tidal inlet behavioural analysis. Proceedings 17th Coastal Engineering Conference, ASCE, pp 2461–2480Google Scholar
  18. Nielsen AF, Gordon AD (2008) The hydraulic stability of some large NSW estuaries. Aust J Civ Eng 5(1):49–59CrossRefGoogle Scholar
  19. Nielsen AF, Gordon AD (2011) The impact of entrance breakwaters on large estuaries. IAHR, Brisbane, June, 8 ppGoogle Scholar
  20. Nielsen AF, Gordon AD (2015) The impact of entrance jetties on the hydraulics and ecologies of large estuaries. Shore Beach, 83, 3, Summer 2015, 43–58.Google Scholar
  21. NSW MER (2007) Wetlands monitoring evaluation and reporting program. Assessing the extent and condition of wetlands in NSW. NSW Government Office of Environment and HeritageGoogle Scholar
  22. O’Brien MP (1931) Estuary tidal prism related to entrance areas. Civ Eng 1(8):738Google Scholar
  23. O’Brien MP (1969) Equilibrium flow areas of inlets on sandy coasts. ASCE Proc J Waterw Harb Div 95(WW1):43–52Google Scholar
  24. O’Brien MP, Dean RG (1972) Hydraulics and sedimentary stability of coastal inlets. Proceedings 13th Coastal Engineering Conference, ASCE, pp 761–780Google Scholar
  25. Pennington, J (1877) In: Oyster Culture Commission, 1877. Report of the Royal Commission, appointed on the 29th September, 1876 to inquire into the best mode of cultivating the oyster together with the minutes of evidence, and appendices. Charles Potter Acting Government Printer, Sydney, 57 pp. Appendix, p. 65Google Scholar
  26. Seabergh WC (2003) Long-term coastal inlet channel area stability. Proceedings Coastal Sediments ‘03, CD-ROM, World Scientific & East Meets West Productions, Corpus Christie, 8ppGoogle Scholar
  27. Seabergh WC, Kraus NC (1997) PC program for coastal inlet stability analysis using Escoffier method. CETN IV-11, US Army Corps of Engineering, Waterways Experiment Station, Coastal & Hydraulics Laboratory, DecemberGoogle Scholar
  28. Skou, A (1990) On the geometry of cross-section areas in tidal inlets, Series Paper No. 51, Institute of Hydrodynamics and Hydraulic Engineering, Technical University of Denmark, LyngbyGoogle Scholar
  29. Van de Kreeke J (1992) Stability of tidal inlets; Escoffier analysis. Shore Beach 60(1):9–12Google Scholar
  30. Watterson E (2010) Tidal modelling of Lake Macquarie. WorleyParsons Report 301020-02167 – 01 prepared for Lake Macquarie City Council, September, 125ppGoogle Scholar
  31. West RJ, Thorogood CA, Walford TR, Williams RJ (1985) An estuarine inventory for NSW, Australia. Fisheries Bulletin 2, Department of Agriculture NSWGoogle Scholar
  32. Williams RJ, West G, Morrison D, Creese B (2006) Estuarine Resources of New South Wales’. In: a 2-part DVD pack published by the NSW Department of Planning. Australia, Sydney. http://www.dpi.nsw.gov.au/content/research/areas/aquatic-ecosystems/outputs/2006/709

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  1. 1.Advisian WorleyParsonsSydneyAustralia
  2. 2.Coastal Zone Management and PlanningNorth NarrabeenAustralia

Personalised recommendations