Nearly 20,000 homes could be built on or near high-risk flood areas across Norfolk.

At least 12 sites, which have been earmarked for large developments of more than 500 homes, are either on or close to areas that have the highest risk of flooding, research by this newspaper shows.

We matched data from the Environment Agency with sites where Norfolk councils want to build more than 500 new homes to see which ones are close to areas marked as flood zones.

MORE: Where thousands of new homes could be built, transforming every area of Norfolk

The figures do not include developments of less than 500 homes or the possible effects of climate change, meaning the figure of 20,000 is likely an underestimate.

One of the sites in a flood area is the Deal Ground in Trowse, where outline planning permission was granted for up to 670 homes in 2013.

Six years later work has yet to begin, but Norfolk-based developer Serruys Property Company, which owns the site, said building should start next year.

While most of the site falls within flood zone two (medium risk), some parts overlap high-risk flooding areas between the River Yare and River Wensum.

According to planning documents, building on the site was given the go-ahead because of the "economic benefits" of it and size of the site.

Norwich Evening News: Residents at Farman Way, Blofield, say flooding in the area is being made worse by water running off a nearby field. Picture: ArchantResidents at Farman Way, Blofield, say flooding in the area is being made worse by water running off a nearby field. Picture: Archant (Image: Archant)

It added that the flood risk would be reduced by building "flood storage".

Another 2,650 homes have also been proposed south-west of Attleborough and 44 homes in Colegate, Norwich, near flood zones.

Some families on new builds are already dealing with the effects of flooding, despite not living on flood zones.

At the Farman Way development in Blofield, residents say flooding is being made worse by water running off a nearby field which is yet to be landscaped by developer Norfolk Homes Ltd.

Norwich Evening News: The A47 at Blofield was severely flooded during the heavy downpour in October. Photo: BroadsBeatThe A47 at Blofield was severely flooded during the heavy downpour in October. Photo: BroadsBeat (Image: BroadsBeat)

Resident Demetris Mavroudis said: "The problem we have is with all the water coming off the land.

"It runs down the road because the land has not been levelled.

"Hundreds more homes are being built in the area and we are worried they are going up without thinking about the flooding."

A Norfolk Homes Ltd spokesman said the work had not yet been completed because Norfolk County Council and Broadland District Council were looking its potential use as a playing field.

Norwich Evening News: Flooding in Blofield during heavy rainfall in October 2019. Picture:Flooding in Blofield during heavy rainfall in October 2019. Picture: (Image: Thana Wareesaengtip)

He said: "We simply carried out an initial levelling and seeded exercise on the area to make it look more aesthetically pleasing to our residents and the adjoining residents in the intervening period. It is by no means in its finalised state.

"Moving forward we are fully committed to working with the residents, the district council and the parish council to alleviate all concerns with regards to water run off during peak rainfall periods."

The village is located north of the River Yare, where large areas of marshland falls under flood zone three (high risk).

Thana Wareesaengtip, manager at The King's Head in Yarmouth Road, said the torrential rain in October, which saw large areas of Norfolk flooded, caused major problems outside his pub.

Norwich Evening News: Flooding in Blofield during heavy rainfall in October 2019. Picture:Flooding in Blofield during heavy rainfall in October 2019. Picture: (Image: Thana Wareesaengtip)

"It nearly came inside," he said. "The water was quite high; it covered the pavement."

He said he feared the drainage system would not be able to cope with more homes in the area as they already overflow during heavy rainfall.

Meanwhile, in west Norfolk, a site in West Winch, between the A10 and A47, is earmarked for 3,200 homes and in Wisbech an area off Burrettgate Road could have 550 homes built.

Both sites border high-risk flooding zones which stretch across the Fens and into Lincolnshire.

Norwich Evening News: The A47 near the Blofield roundabout flooded during heavy rainfall in October. Picture: Sunny DaisThe A47 near the Blofield roundabout flooded during heavy rainfall in October. Picture: Sunny Dais (Image: Sunny Dais)

While the low-lying areas benefit from flood defences, the villages east of King's Lynn were also hit by isolated floods in the October downpour.

Plans to build ten homes off Hall Road in Clenchwarton were given the go ahead on October 7 by West Norfolk council, despite objection from the parish council.

They said two newly-built homes nearby had caused other properties to suffer "extreme flooding every time it rains".

A West Norfolk council spokesman said: "The majority of the areas allocated for development on the Wisbech fringe and at West Winch fall within flood zone 1."

Norwich Evening News: Police letting cars through the flood on the A47 past the Honingham roundabout in October 2019. Picture: Nia HowePolice letting cars through the flood on the A47 past the Honingham roundabout in October 2019. Picture: Nia Howe (Image: Nia Howe)

They said the flood risk had to be considered when choosing them for development.

Environment Agency guidance states that if a site contains a range of flood zones, development should be put in areas of lowest flood risk.

A spokesman said: "We are also consulted on all proposals within 20 metres of main rivers. The majority of our advice is bespoke."

Half of the 12 proposed sites for development are in the Greater Norwich Local Plan (GNLP).

Norwich Evening News: The road near Blofield Heath flooded in October 2019 while drivers were stuck in all directions as they were unable to get onto the A47. Picture: Amber KnowlesThe road near Blofield Heath flooded in October 2019 while drivers were stuck in all directions as they were unable to get onto the A47. Picture: Amber Knowles (Image: Amber Knowles)

One such site is a potential new garden village settlement near Hethel, which could have between 2,000 and 5,160 homes.

But the River Tiffey cuts across the site, making it vulnerable to flooding, according to the Environment Agency map.

Another site located south of Wymondham has been proposed for 1,500 homes, despite the high flood risk near the Bays River.

Other GNLP sites near high-risk flood areas include 3,000 homes near Hethersett, 1,000 homes near Marsham, 600 homes at Forncett St Peter and a new garden village at Honingham Thorpe.

Norwich Evening News: Flooding onThieves Lane and Besthorpe Road in Attleborough during the torrential rain. Picture: Jon MouleFlooding onThieves Lane and Besthorpe Road in Attleborough during the torrential rain. Picture: Jon Moule (Image: Jon Moule)

A GNLP spokesman said: "New development will generally be guided away from areas with a high probability of flooding.

"Where new development in such areas is needed for reasons of sustainability, flood mitigation will be required and flood protection will be maintained and enhanced."

Norwich Evening News: Flooding onThieves Lane and Besthorpe Road in Attleborough during the torrential rain. Picture: Jon MouleFlooding onThieves Lane and Besthorpe Road in Attleborough during the torrential rain. Picture: Jon Moule (Image: Jon Moule)

Norwich Evening News: Flooding in Poringland after Sunday's downpour. Photo: SubmittedFlooding in Poringland after Sunday's downpour. Photo: Submitted (Image: Archant)