Coastal Defences Under Attack Selsey’s sea defences have a lot to contend with. The peninsula has always been subject to constant pressure from the sea, but now climate change is intensifying its impact. The current defences are coming to the end of their serviceable lives making stormier seas a serious challenge for Selsey.
A Changing Climate ‘Climate change’ refers to changes in climatical patterns relating to increased greenhouse gas emissions. For coastal management, climate change is forecast to result in increased flooding and erosion through sea level rise and an increase in extreme storm events. This additional pressure is leading to a decreasing level of protection provided by the existing defences. In England, rising sea levels and climate change have put around 2.4 million properties at risk of flooding from rivers and the sea.
Sea Level Rise Data Changes in Sea Level Portsmouth Sea level has risen by ~1.77mm per year.
Southampton Sea level has risen by ~1.69mm per year.
1930
1940
1950
1960
1945: The end of WW2
1970
1980
1966: England wins the World Cup
1990
2000
1993: The WWW gets launched to the public
2010
2020
SOURCE: Standing Conference on Problems Associated with the Coastline (SCOPAC) Storm Analysis 2020.
2011: Prince William marries Kate Middleton
The latest sea level rise data is published in the UK Climate Projections 2018 (UKCP18). The UKCP18 information captures assumptions of the predicted increase in temperature using a range of emissions scenarios. The graph below shows the predicted sea level rise at Selsey based on two different UKCP18 climate change projections for a high emissions scenario. Design standard – This represents a reasonable estimate of expected conditions, incorporating an element of precaution while balancing cost-effectiveness. Sensitivity testing – Used to assess the potential impact of more extreme scenarios. This helps in evaluating adaptability and resilience to more severe but less probable flood events.
Predicted Sea Level Rise 2
© Coastal JJ
Sea Level Change (m)
1.5
SLR for sensitivity testing
SLR projection for design standards
1
0.5
0.0 2000
2025
2050
2075
2100
2125
Year
Asset Condition & Maintenance There are a wide range of coastal defences along the Selsey coastline, including seawalls, rock revetments, groynes, and shingle beaches. Whilst regular maintenance work has been carried out on the existing groynes and seawalls, such repairs are becoming increasingly difficult because many of these structures are nearly 80 years old and need replacing due to their aging condition. Selsey’s coastal defences are owned by several different individuals and organisations.