Coastal flooding can arise from a combination of high tides, wind induced tidal surge, storm surge created by low pressure and wave action. There is also the likelihood of a general rise in sea level caused by climate change.
The disastrous flooding of 1947 was induced, in part, by an exceptional tidal surge in the North Sea. The predictions are for our weather to become more extreme. The combination af all these effects is that coastal flooding is likely to become more frequent and more severe.
Sea walls are fine until they are overtopped or fail. Then the water level behind the wall can rise very rapidly and there is a much greater risk of drowing than if the level had risen gradually.
Coastal defences are a major capital investment, which must be justified as a reasonable use of limited resources. The coastlines are constantly changing, and it may be difficult or impossible to influence the geological changes in shoreline other than in the very short term. This may be difficult to accept if it is your house falling into the sea.
Most flood and coastal defences are funded, in part, by the Ministry of Agriculture, Fisheries and Food (MAFF), and are subject to a rigorous cost-benefit analysis. A methodology has been developed by Middlesex University to put a value on anything, even a view, and this is used as the basis of evaluating options for flood defences. Information on this is available on the MAFF website.