Coastal flooding is caused by extreme tidal conditions that occur because of three main mechanisms, either individually or in combination.
- High tide levels – variations in tidal levels due to gravitational effects of the sun and moon can result in higher sea levels – there is an approximate twice daily variation between high and low tide, onto which is superimposed a spring-neap tide cycle when extra high and low tides occur.
- Surge – an increase in sea level above tidal level caused by low atmospheric pressure which may be exacerbated by the wind acting on the sea.
- Wave action – dependent on wind speed and direction, local topography and exposure.
In April 2008, the Environment Agency (EA) took on a strategic overview role on the coast in England. This allows for one organisation to have an overarching role in the management of the coast.
The Environment Agency is the lead body for protecting our coastline from flooding. Local authorities continue to take the lead in managing coastal erosion risk, under the overview of the EA. Both operating authorities carry out coast protection measures to reduce the risk of flooding and to protect against erosion.
In the past, these schemes would have been directly funded by the Department for Environment Food and Rural Affairs (Defra). Since taking on the strategic overview role, Defra still funds these schemes, but funding is now administered by the EA. This includes prioritising and distributing the government's budget for all capital works for sea flooding and coastal protection.
The EA also has a responsibility to manage, review and approve 'shoreline management plans' on behalf of Defra. Shoreline management plans continue to be drawn up by those who are best placed to do so.
The EA also considers the impacts of ‘coastal squeeze', which may result in natural habitats being unavoidably lost. Some forms of sea defence can have a negative impact on the coastal environment. 'Coastal squeeze' occurs when coastal habitats like salt marsh, mudflats or beaches become caught between sea defences and rising sea levels. This can result in the gradual loss of these habitats – which has already been happening for decades. As these are important feeding grounds for birds and other wildlife, it can have serious environmental consequences. Inter-tidal habitats are also important for local commercial fisheries, as they provide important nursery areas. The EA seeks to replace them elsewhere through regional 'habitat creation programmes'.
It is recognised that there will be a need to balance existing land uses in these areas with the requirement to replace protected habitats lost through coastal squeeze.