A major incident has been declared amid widespread flooding in the Midlands while the south of England faces another deluge of rain.

A yellow weather warning has been issued by the Met Office for rain across the south with rail services warning passengers of delays and cancellations due to the severe conditions.

It comes just days after disruption caused by strong winds and rain from Storm Henk, which has left the ground saturated and more prone to flooding, according to forecasters.

Nottinghamshire County Council said a major incident was declared “due to rising levels along the river Trent” and that residents who live in flood risk areas should be prepared to evacuate their homes.

It added that the latest forecasts were showing that peaks along the river Trent could “come close to the highest levels on record from the year 2000”, adding that residents in areas along the Trent valley should be “prepared for flooding”.

A man stranded on his shed roof by floodwater was rescued by a crew from Highfields Fire Station who used a boat to bring him safely bring to land.

In a statement, Nottinghamshire County Council said: “Key tributaries which feed in to the river Trent, including the river Derwent, the river Soar and the river Dove, have already reached their peaks and high water levels will now pass down the Trent, which is likely to lead to the flooding to properties and roads.

“Residents who live in the flood risk areas are being asked to ensure they have preparations in place in case they are asked to evacuate. Councils, emergency services and the Environment Agency have been providing emergency support to communities impacted and will continue to provide support across the county.”

Several residents of Radcliffe Residential Park, an estate of static caravans for the over-55s just to the east of the city, have been evacuated due to high water levels.

Laurie Walker, chairman of Radcliffe Park Residents’ Association, said: “Some were evacuated last night. There’s one gentleman who is quite poorly and during the previous flood, he had to be airlifted out and put in a local home.

“I’ve had someone knock on my door to say the water is going to rise another 25cm. Outside their front doors, it’s like a river, I don’t know if the homes have been flooded.

“To come out of the park I’ve had to walk through somebody else’s garden to avoid the flood on the road. It’s the worst it’s ever been, I’ve been here seven years. It’s a mess.”

Anne McLeod, of Radcliffe-on-Trent Parish Council, said: “It’s directly adjacent to the Trent so they get it quite badly, but in my memory, and I’ve lived in Radcliffe since 1975, this is the highest it’s been since 2000 when it last flooded that area.”

She added that several homes are without electricity.

Elsewhere, a number of cows drowned in the village of Sawley, Derbyshire, prompting an animal welfare investigation.

Great Western Railway (GWR) advised travellers against starting their journeys by rail on Thursday afternoon because of “heavy rainfall forecast on already flooded ground”.

In a statement posted on social media, GWR said: “Those who have already travelled should consider making the return journey as soon as possible.”

The train operator said its direct route between Swindon and Bristol Parkway remains closed because of flooding on tracks during Storm Henk.

GWR said that Network Rail had identified “key sites in Wiltshire, Somerset, Devon and Cornwall as being at risk of flooding” from about 3pm on Thursday, adding that “trains may not be able to operate through these areas”.

It added that these “most at risk” locations included sites between Swindon and Bristol Temple Meads via Chippenham and Bath Spa, Newton Abbot and Plymouth, Exeter and Tiverton Parkway, Bristol Temple Meads and Weston-super-Mare, and Taunton and Westbury.

South Western Railway (SWR) said “extreme rainfall” forecast in the South of England meant that customers should expect “severe disruption on the South Coast, south of Guildford and west of Basingstoke” from 1pm to 7pm on Thursday.

SWR said in a post on social media: “Later in the evening, there will likely be a significant knock-on impact on any services which serve these areas, meaning further disruption for the rest of the day”.

The Met Office issued a yellow weather warning of rain from 12pm on Thursday with rainfall expected to travel in a north-east direction across the south of England, lasting until 3am on Friday.

It added there is a “small chance” that communities could become cut off by flooded roads.

Following rainfall in London, a party boat which acts as a floating bar, restaurant and nightclub sank in the River Thames.

A spokesperson for the Bar & Co boat, which was moored at Temple Pier, said: “Likely it sunk because of weather conditions.”

The warning comes in the wake of Storm Henk that battered the UK on Tuesday and forced people to evacuate their homes, leaving one man dead from a tree falling in 90mph winds on the Isle of Wight.

The Met Office added that the spell of rain on Thursday was falling on already saturated ground which could cause “further flooding and travel disruption”.

It said: “The track of the heaviest rainfall remains very uncertain, but there is a chance of 20 to 30 millimetres falling in six to nine hours across a portion of the warning area, with a few places perhaps seeing 40 to 50 millimetres.

“Impacts are more likely due to the current very wet ground across the region.”