Alverstoke Scheme FAQs
Global sea level has been rising over the past century, and it is the dominant factor of increased coastal flood risk. With continued ocean warming, sea levels are predicted to rise for many centuries at rates higher than that of the current century. Alongside this, flooding in the UK is often associated with extreme weather conditions, such as storm surges, which are becoming more common. The new sea defences at Alverstoke are being constructed to make sure it is protected in line with these predictions and threats.
For more information and a summary of the most recent climate projections for the UK visit here.
The sea defences will consist of a reinforced concrete wall and a floodgate which will span the width of Little Anglesey road. The new defences will be approximately 100m in length and 1m high. The outer face of the wall (east facing) will be matched to the appearance of the existing wall. They will be located at the western end of Stoke Lake, between Little Anglesey Road and Clayhall Road.
Construction started in January 2022 and is due to be completed in summer 2022. Some construction noise should be expected from material movements, breaking out the existing path and general movement of construction equipment within the site area. Little Anglesey Road will be closed for a limited period whilst the flood gates are being installed. There will be advance warning of any road closures and diversions will be put in place.
The floodgate will be the same height as the wall and span the road and associated footway. It will be a steel construction with timber cladding for the side which is visible when in the open position. A typical example of this is shown here.
It is estimated on average that the flood gate would need to be closed about once a year in the first ten years of its operation, but the exact number of times will depend on the variables such as the tide levels of weather conditions at the time. Due to climate change and sea-level rise, this frequency is likely to increase in future years.
The double leaf floodgate will be manually operated. GBC will close the gate in consultation with the Environment Agency Flood Incident team with support from Coastal Partners who have a duty officer system in place for Coastal Flood Response.
This setup occurs in other local authorities which form Coastal Partners and builds on 15 years of experience installing flood equipment and working with local authority emergency planning teams.
In a high-water event, when the floodgate is closed, there will be a diversion route signposted in the area for pedestrians and vehicles to travel around the closed road.
The scheme does not increase flood risk to any properties outside of the protected area.
The Jackie Spencer Bridge design option was discounted for a variety of environmental, technical, and economic reasons which can be read about here. Following assessment of this option by Coastal Partners, it was determined that the leading option remained as the most technically feasible, environmentally acceptable, and financially viable design option going forward.
Coastal Partners may bid for Defra grant to try and deliver property level flood resilience to those properties which are not likely to be protected by coastal defence structures in Gosport. However, there is no guarantee that funding will be available, and it is likely that homeowners will also need to contribute financially in some way towards any solution
Gosport Borough Council is a Risk Management Authority, like the Environment Agency, they are not legally required to do anything to protect against flooding and erosion, however they have permissive powers to carry out works where there is a wider public benefit, clear economic benefit and an achievable solution; such as at Alverstoke. In the absence of anything else private landowners have ultimate responsibility for protecting their own property from flooding and erosion, but must act within statutory planning regulations and other applicable legislation.
Further information is available here: https://coastalpartners.org.uk/flood-risk