Storm surge

Storm surge is an abnormal rise in sea level over and above the normal (astronomical) tide levels, due to the presence of a storm. The powerful ocean movements are caused by strong winds piling water up against the coast and by wave runup to the shore[8]. The result of storm surges include rapid erosion, transportation, and deposition of sediment. New tidal inlets may be opened, and previously opened inlets may seal. Beaches and dune systems may move inland. Storm surges also have a devastating impact on life and infrastructure[4][3].

Storm surge

is at the most dangerous when it arrives at high tide - when the sea is at it's highest point[8].

A lot of coastal flooding is the result of storm surges. A storm surge is only measured by the water level that exceeds the normal tidal level, excluding waves. Several meteorological factors contribute to a storm surge and its severity:

• Water is pushed towards the coast over a long fetch by high-speed winds
• The shallowness and orientation of the body of water
• The tidal range, timing and height of tides (notably spring tides)
• A drop in atmospheric pressure
• Seasonal sea surface temperature cycles, e.g. El Nino etc.[5]

A storm tide is the water level that results from the combination of a storm surge with tides under average meteorological conditions[7][8].

Storm surges are exacerbated through a variety of factors such as:

• Land subsidence - through tectonic activity or post-glacial adjustment.
• Removing natural vegetation - As mentioned previously, mangroves protect against extreme weather events like cyclones.
• Global Warming - As the surface of oceans gets warmer, the frequency and intensity of storms will increase; As a result, the severity and height of storm surges and flooding will increase.

Coastal wetlands and storm surges

Coastal wetlands, including shallow subtidal wetlands protect the coastline during storm surges by reducing storm surge flooding and damage. Terrain roughness, width of the tidal flats and the structural complexity (rugosity) of intertidal and shallow subtidal macrobiota such as coral reefs and mangroves all reduce wave heights and wind speeds[2]. Intertidal wetlands are an important natural barrier that mitigates exposure and vulnerability to storm surges by this reduction in flood extent. Areas with larges swathes of coastal wetlands have the potential to avert up to 90% of the damage from coastal storms like cyclones and hurricanes, and as a result, storm surges[1][6]. However, storm surges and their associated severity under climate change also damages coastal wetlands, reconfiguring the coastline, estuaries and waterways, for example opening up vulnerable intermittently closed and open lagoon lakes (ICOLLs) to the sea[3].

Wetland management and storm surges

The value of coastal wetlands for protection for storm surge is one of the many co-benefits for coastal wetland protection rehabilitation – refer to Wetlands and disaster managment. Careful planning to retain natural coastal wetlands in the coastal zone is needed to avoid the ‘coastal squeeze’ where wetlands are sandwiched between development and the coastline. Taking a whole-of-system, values-based approach to retention and rehabilitation of coastal wetlands and floodplains for storm surge protection as well as general biodiversity benefits is recommended.

Links and references

Wetlands and disaster managment

Storm surges and coastal flooding - Queensland Fire and Emergency Services

Get Ready Queensland - Storm surges

Storm tide monitoring sites

References

1. ^ Al-Attabi, Z, Xu, Y, Tso, G & Narayan, S (21 March 2023), 'The impacts of tidal wetland loss and coastal development on storm surge damages to people and property: a Hurricane Ike case-study', Scientific Reports. [online], vol. 13, no. 1, p. 4620. Available at: https://www.nature.com/articles/s41598-023-31409-x [Accessed 1 September 2023].
2. ^ Carlot, J, Vousdoukas, M, Rovere, A, Karambas, T, Lenihan, HS, Kayal, M, Adjeroud, M, Pérez-Rosales, G, Hedouin, L & Parravicini, V (30 January 2023), 'Coral reef structural complexity loss exposes coastlines to waves', Scientific Reports. [online], vol. 13, no. 1, p. 1683. Available at: https://www.nature.com/articles/s41598-023-28945-x [Accessed 12 October 2023].
3. ^ a b Glamore, WC, Rayner, DS & Rahman, PF (2016), Estuaries and climate change. Technical Monograph prepared for the National Climate Change Adaptation Research Facility.. [online], Water Research Laboratory of the School of Civil and Environmental Engineering, UNSW. Available at: https://coastadapt.com.au/sites/default/files/factsheets/T3I6_Estuaries_and_climate_change_0.pdf.
4. ^ Hamblin, WK & Christiansen, EH (2001), Earth's dynamic systems, Prentice Hall, Upper Saddle River, NJ.
5. ^ Meteorological Effects - About Tide Predicitions - Bureau of Meteorology. [online] Available at: http://www.bom.gov.au/australia/tides/about/p3a-met-effects.shtml [Accessed 12 October 2023].
6. ^ Mulder, OJ, Mulder, KP, Kubiszewski, I, Anderson, SJ, Costanza, R & Sutton, P (December 2020), 'The value of coastal wetlands for storm protection in Australia', Ecosystem Services. [online], vol. 46, p. 101205. Available at: https://linkinghub.elsevier.com/retrieve/pii/S2212041620301479 [Accessed 1 September 2023].
7. ^ Queensland Government, Glossary | Storm tide monitoring. [online] Available at: https://www.qld.gov.au/environment/coasts-waterways/beach/storm/storm-glossary [Accessed 12 October 2023].
8. ^ a b c Storm Surge. [online] Available at: http://www.bom.gov.au/cyclone/tropical-cyclone-knowledge-centre/understanding/storm-surge/ [Accessed 1 September 2023].

Last updated: 12 October 2023