Cornish villages warned to expect extreme flash floods like Boscastle and Coverack in the future

• Watch Charlotte Gay's report

Life-changing levels of flooding is predicted to become more frequent for coastal communities similar to Boscastle and Coverack in the coming years.

Cornwall's geography is quite unusual for the British Isles so it has a particular set of climate issues which will become more extreme in the next 100 years.

Climate change professor Stephan Harrison says while summers will get "really hot" this will lead to an increase in flash flooding in "rapid response catchments".

Places such as Lamorna with "very narrow valleys which come off which flow into the sea" will be most at risk.

"Because of the nature of the Cornish landscape what will happen is that those will become increasingly vulnerable to these rapid floods," he said.

"We've seen them already in Boscastle in 2004, and in Coverack on the south coast in 2017. We've got to prepare for those. They are very intense, very unusual, very high magnitude. That will require probably quite a lot of money being spent on on flood defences."

On 18 July 2017 more than 200mm of rainwater was recorded in three hours in Coverack. It was described as "the most intense rainfall ever recorded in the UK" by Cornwall Council's flood and Coastal environment lead.

Dave Watkins told the neighbourhoods overview and scrutiny committee: “Coverack had the same amount of rainfall as Boscastle but it happened in half the time."

Penny and Chris Hammill were airlifted from their home when suddenly "six feet of water" flooded their kitchen.

Penny said: "If we hadn't have got the stairs there we probably would have drowned because the water was too fierce."

"Every time there is heavy rain we always think is it going to come again like that."

Neighbours Bob and Jane Dunnett were astonished by how the flood water turned their home "into an island" and their garden wall was "simply knocked down" as it came "pouring through like a river".

They didn't have to be evacuated from their home and June says she can't see that level of flooding happening in Coverack again.

"I would be very surprise to see it again at that level. It was so localised, people in Helston and round about could see it but they were in sunshine close by."

Climate change scientists produced a specialist report specifically for Cornwall to encourage people to prepare for how they’ll live with rising sea levels, extremes in temperatures and changing landscape of the duchy.

The report argues flood defences may need to be updated all around the county. In Truro Councillor Martyn Alvey, the cabinet lead for the environment, says the current floodgates are set to be "overtopped" more frequently.

"The floodgates are here to protect Truro from particularly high tides and storm conditions. At the moment the Environment Agency close them about 30 times a year.

"By 2050, that will be at least 60 times a year and not all of those occasions the floodgates will actually do the job to protect Truro because they could well be overtopped."

• Flooding health implications

Flooding is something many people across the West Country have adapted to over the years but the Climate Change Risk Management scientists say it also has a very serious impact on people's health.

In the short term this could be the ability of the emergency response to react to these extreme flooding events and the pressure it would put in the Royal Cornwall Hospital and other health services.

People could also become unwell if they are exposed to contaminated water such as infectious and parasitic illness from contact with sewage-contamination.

In the long term, people could face psychological trauma because of the damage to homes and property, loss of livelihood and fear of it happening again.

Extreme events and disasters can exacerbate or compound pre-existing mental health needs and it can also trigger a loss of sense of place, anxiety and grief related to a changing climate.

There are also more insidious effects such increased year-round humidity leading to damp houses, with the concomitant long-term health impacts. These can create cascading effects. At most risk are those who already experience health inequalities.