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Coastal flooding and inundation

Coastal flooding is the temporary flooding of low lying coastal land which is not normally affected by actions of the sea. Coastal flooding is typically a result of abnormally high tide, waves and/or storm surge resulting from severe weather. Coastal inundation occurs when coastal land is left permanently submerged or flooded by the sea. 

In addition to a rise in sea level, a changing climate might result in more frequent and intense storm activity. The combined impact of rising sea level and severe weather will increase both the area flooded and the frequency at which widespread flooding is experienced along the coast. This will have impacts on coastal infrastructure, development and environments.

Because of the risk that coastal flooding and inundation poses to coastal communities, it is a hazard that must be considered when developing or managing the coast. To mitigate the risk of flooding to coastal development, the Coast Protection Board has developed policies that recommend specific site and floor levels relative to for each coastal settlement within South Australia. The sea level rise allowance used in South Australia is 0.3 metres up to 2050.  Coast Protection Board policy also requires that the development is capable, by reasonably practical means, of being protected or raised to withstand a further 0.7 metres of sea level rise to the year 2100.

Floor levels are determined by a combination of on-ground survey and desktop analysis that takes into account allowance for wave effects, storm tides, existing or proposed flood control measures, current and future land subsidence and sea level rise. The database of recommended levels for coastal development is regularly reviewed and maintained to ensure it is accurate.  These levels are applied to all development applications received by the Coast Protection Board.

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