Watch: Car drives through deep flooded water on Thorney Island causeway - as locals fear being stranded again amid rising water levels

Residents and those needing access to the peninsula required military carriers to transport people across the 500 metres of flood over The Great Deep causeway onto and off the island at the start of November and in late October. The road flooded extensively for three weeks as rain battered the region.

READ NOW: Firefighters rescue horses

The causeway was left swamped in around 18in of water, leaving hundreds of cars parked up on the mainland side of the island as people battled to get to jobs and schools. When on the island, many were then forced to walk up to two miles to get to their destinations.

Claire Brown, who has a horse on the island she regularly visits, said of the flooding impact last time: “Friends had their cars written off, I suffered £500 bill for water ingress into my car, and my lorry now has an engine management warning that we cannot identify and has required a new starter motor due to the salt water. Sadly there are many many similar stories.

“My main issue is that I am unable to access my horse which I pay livery for. There is a great deal of logistic inconvenience and damage to vehicles. But seeing the nature reserve washed away as the birds lose their nests, the browning of the pastures and killing of the trees and hedges is just heartbreaking as it really is a beautiful sanctuary over there.”

She continued: “Now six weeks on and the flooding has started again. You cannot get hold of Southern water for love nor money and we don't know how bad it's going to get, whether our lives are going back on hold again or how long this will last this time.

“We don't know if Southern Water intends to pump for three weeks and then cease again. Either way, hundreds of residents, military personnel and amenity users will have their lives disrupted again.

“Ecologically it's a disaster too. The devastation from last time is phenomenal; my fishermen friends at the marina and local business owners are estimating £10m damage to the local economy due to the loss of the oyster beds. And the sea is now so diluted with fresh water that the sea fish have now moved away; apparently they will take eight-12 years to re-establish. This is only going to get worse every time flooding happens and the impact will get worse.”

Another resident, speaking at the end of October, said: “The flood is currently covering the only entrance and exit on/off Thorney island where over 1,000 people live and work. I would like to stress it is not just military personnel that are having to live with the consequences of this extreme flood as many service personnel live on the island with their families.

“The flooding has been caused by a sluice gate issue that is not controlling the influx of sea water onto the island, the curb is now submerged into the sea water most of the day,

sometimes dipping just below it when the tide has gone out. For the past two weeks I have been forced to drive through the flood to get to work which has resulted in a massive amount of damage to my car as it is sea water, causing brake pads to rust, debris in the water causing tyres to puncture not to mention other damage driving through deep sea water can cause to your car. It has now reached a depth that is dangerous to drive through and several cars have gotten stranded in the water.

“I have had to take time off work (resulting in loss of income) as I cannot make it out of Thorney without risking my car breaking down. Everybody who lives or works on the camp is taking the same risks each day that nothing continues to be done to help the situation, with an apparent ongoing row between the Environmental Agency and Southern Water as to whose liability it is to fix it.”

The Ministry of Defence (MOD), Southern Water, Chichester Harbour Conservancy, and the Environment Agency have all been in discussions about how to reduce tidal flooding on the island. Some of the sluice gates that control the flow of water are said to be the route of the problem but are in need of repair. And questions remain over who is responsible for them with talks ongoing to decide this.

A spokesperson for Southern Water said: “We’re continuing to work with the Environment Agency and the Ministry of Defence to explore options to reduce tidal flooding on Thorney Island. This work includes a temporary fix to alleviate current issues, as well as the exploration of a longer-term approach once roles and responsibilities relating to the eastern tidal sluice gate are agreed. We know how concerned local residents are about this issue and we will continue to engage fully with all parties to help find the best solution.”

An Environment Agency spokesperson said: “We continue to work in partnership with Southern Water and the MoD to mitigate flooding to the main access road at Thorney Island, West Sussex. Whilst options are being considered to deliver a permanent flood management solution, we are carrying out emergency works to prevent further tidal water impacting the area which are expected to be completed by Christmas.

“We would urge local people to always check their flood risk online at www.gov.uk/flood or via Floodline: 0345 988 1188. To report flooding call our 24/7 incident line on 0800 80 70 60.”