Flood Risk Assessment in Yorkshire

A flood risk assessment in Yorkshire starts with two questions: which water can reach the site, and which council will judge it. Rain on the Pennines runs east through the Aire, Calder, Don, Wharfe, Swale and Ure into the Ouse and out through the tidal Humber, while the cities flood from overloaded drains, the Wolds from groundwater and Holderness from a retreating coast. We prepare flood risk assessments across the county for planning, property purchase and insurance, alongside sequential and exception tests and drainage strategies.

This page covers the four ceremonial counties: North Yorkshire, West Yorkshire, South Yorkshire and the East Riding of Yorkshire, which most people simply call East Yorkshire. That takes in the cities of York and Hull, and in the north Middlesbrough and Redcar and Cleveland, which sit inside ceremonial North Yorkshire. Fifteen councils act as Lead Local Flood Authority somewhere in it, and two national park authorities, for the Yorkshire Dales and the North York Moors, decide planning applications inside their parks.

Around 500,000 people live in areas the tide can already reach around the Humber and its tidal rivers, Hull, Goole, Selby and Doncaster among them, according to the Environment Agency's July 2026 evidence for the Humber 2100+ strategy.

To talk through a Yorkshire site with one of our flood risk consultants, call 01293 214444 or email enquiries@unda.co.uk.

Check any Yorkshire postcode against the Environment Agency's maps

Enter a postcode below to see the Environment Agency's flood zones, surface water and reservoir mapping around it, or open our full flood risk map for anywhere in England. That answers the first question most people have. Is the postcode in Flood Zone 2 or 3? An East Riding flood risk map shows the same national data as one for York or Leeds. None of them can show floor levels, the state of a defence or a culvert under the road, and that is where a site-specific assessment begins.

Flood alerts and warnings in force right now are on the Environment Agency's check for flooding service, which can be searched by town or postcode.

Rivers, tide, groundwater and drains: what floods in Yorkshire

Almost every source of flooding is present somewhere in Yorkshire, and many sites face two or three at once. Most of the county drains through one river system: the Swale, Ure, Nidd, Wharfe, Aire, Calder, Don and Derwent all reach the Ouse, which meets the Trent at Trent Falls to form the Humber. The pattern changes from west to east, from steep Pennine valleys that rise fast to flat, pumped land around the estuary where the tide holds the rivers back.

Five of these rivers have pages of their own: the River Aire, River Calder, River Don, River Wharfe and, on the northern edge, the River Tees. The River Trent page follows the river that joins the Ouse at the head of the Humber. The Yorkshire Ouse, Derwent, Foss, Hull, Swale, Ure and Nidd have no page yet, so they are covered here and on the town pages.

The tidal Humber and the North Sea coast

Around the estuary and up its tidal rivers, flood levels depend on the sea as well as the rain. The Environment Agency's Humber 2100+ evidence summary, published in July 2026 for the partnership of the Agency and eleven councils, sets out what is at stake around the estuary:

• The 2013 surge. On 5 December 2013 around 1,100 properties flooded around the estuary, more than 250 of them in Hull.
• Money spent since 2008. Over £350 million on tidal flood management has improved protection for about 70,000 properties, and keeping the defences in place could cost more than £1 billion by 2046.
• Rising water. UKCP18 projections give the Humber roughly 10 to 15 cm of sea level rise a decade, possibly more than a metre by 2100.
• Hull's own frontage. The Humber Hull Frontages scheme was finished in autumn 2021, and more than £42 million has gone into the city's tidal defences since the surge.
• Still being written. The long-term strategy itself is not finished: in 2026 the partnership was still designing its adaptation pathways.

Being behind a bank does not take a site out of Flood Zone 3. The assessment has to show what happens if that bank is overtopped or breached during the building's lifetime, and how deep and fast the water would be when it arrived. The guide to residual flood risk sets out the method.

Holderness and the cliffs north of Flamborough

The Holderness coast between Bridlington and Spurn loses land every year: the British Geological Survey recorded an average retreat of 1.8 m a year at Aldbrough, and 3.4 m at most. North of Flamborough Head the coast turns to the cliffs and harbours of Filey, Scarborough and Whitby. Two shoreline management plans, River Tyne to Flamborough Head and Flamborough Head to Gibraltar Point, decide whether each stretch is held, realigned or left alone, and our explainer on shoreline management plans covers what those policies mean for a site. On coastal sites we prepare flood risk assessments and due diligence reports, dealing with tidal flooding, wave overtopping and sea level rise.

Reservoirs, moorland and fast-rising becks in the Pennines

West of the Vale of York, rivers rise fast. Above Sheffield the Don can peak within two hours of heavy rain, according to the city's flood risk management strategy, and the same uplands hold dozens of reservoirs: Bradford's 2023 Strategic Flood Risk Assessment counts 22 large raised reservoirs inside the district and 36 that could affect it. Three dam failures or near-failures are part of the county's record:

• Holmfirth, 1852. The Bilberry reservoir embankment gave way in the early hours of 5 February 1852, and 81 people died in the Holme valley.
• Bradfield, 1864. The Dale Dyke Dam failed on first filling on 11 March 1864, killing at least 240 people along the Loxley and in Sheffield; our River Loxley page follows that valley.
• Ulley, 2007. Cracks found in the Ulley Reservoir dam near Rotherham on 25 June 2007 led to about 700 people leaving Whiston, Treeton and Catcliffe, and the M1 was shut between junctions 32 and 36.

For a site below a large reservoir, the Environment Agency's reservoir flood maps show the land a dam failure could reach, and our explainer on reservoir flooding covers how an assessment deals with it. Gauge readings for the Calder, Aire, Don, Ouse and their tributaries are on our live river levels map, the quickest way to see whether a river near a site is running high today.

Slowing the flow above Pickering

On the North York Moors, Pickering Beck and its feeder Levisham Beck run off moorland and forest into Pickering, which flooded in 1999, 2000, 2002 and 2007. The Slowing the Flow project built a bund at Low Hunters Bridge that holds about 120,000 m³ of floodwater, unveiled in October 2015, and added more than 300 leaky dams and 40,000 trees upstream. The Environment Agency estimated the measures cut the Boxing Day 2015 flow by 15 to 20%. Other schemes of this kind are compared in our article on natural flood management.

Chalk springs on the Wolds and pumped land in the lowlands

In the east of the county, two things the river maps leave out decide many sites: chalk groundwater, and land kept dry by pumps. On the Yorkshire Wolds the Gypsey Race, a chalk stream that flows only part of the time, rises in the Great Wold Valley and reaches the sea at Bridlington. The Environment Agency runs a flood alert area for it from Wold Newton to Bridlington, and in 2012 it flooded Burton Fleming up to 0.6 m deep. Water from the chalk can stand for weeks, which is why groundwater flooding is assessed separately from the river.

Much of the low ground around the Humber, the Vale of York and the Don below Doncaster is kept dry by pumps and internal drainage boards. The Shire Group of IDBs notes that mining subsidence has left some of its Yorkshire districts close to 0 m above Ordnance Datum, and its boards keep a 9 m byelaw strip beside their drains and limit new discharges to the greenfield runoff rate. The York Consortium of Drainage Boards runs the Ainsty, Airedale, Beverley and North Holderness, Foss, and Ouse and Derwent boards. What a board can ask of a developer is covered in our note on internal drainage boards.

Yorkshire's flood record since 2000

No two recent floods hit the same part of the county in the same way. That is one reason the councils ask for different things. Each event below comes from Environment Agency, council or review-body records.

1. 4 November 2000. The Ouse at York's Viking Recorder gauge reached 5.40 m, still the highest reading there; our article on York's floods of 2000 tells that story.
2. 25 June 2007. In Hull 8,657 houses and more than 1,300 businesses flooded when the drainage system was overwhelmed and the Bransholme pumping station failed. In Sheffield about 1,200 homes and 1,000 businesses flooded, mostly in the Don valley. The Pitt Review followed.
3. 5 December 2013. A North Sea surge flooded around 1,100 properties around the Humber.
4. 26 and 27 December 2015. Storm Eva put the Aire at Armley to 5.21 m, its highest on record. The Environment Agency counts 2,781 homes and 1,008 businesses affected in Calderdale, and 627 properties flooded in York.
5. 7 and 8 November 2019. The Don at Doncaster rose to a record 6.31 m, and the council's recovery report counts 897 properties directly affected across the borough, Fishlake and Bentley among them.
6. February 2020. Storm Ciara set a record of 3.91 m on the Wharfe at Netherside Hall on 8 and 9 February, and across the month around 1,200 homes and businesses were affected in Calderdale.
7. 20 October 2023. Storm Babet took the Rother at Catcliffe 160 mm above its 2007 record. Rotherham's investigation counts 182 properties and nine businesses flooded inside, 148 of them in Catcliffe and Treeton.

The councils' Section 19 reports behind several of these events are public, and our note on Section 19 investigations explains why some floods are investigated and others are not.

Which council is the lead local flood authority for a Yorkshire site?

The council for the area the site is in. Every authority in Yorkshire is now a unitary or metropolitan council that decides planning applications and also acts as Lead Local Flood Authority, for surface water, groundwater and ordinary watercourses. The national parks are the exception: there the park authority decides the application while the council remains the flood authority. The Environment Agency covers main rivers, the Humber and the sea.

• North Yorkshire Council. A single unitary council since 1 April 2023, replacing the county council and the Craven, Hambleton, Harrogate, Richmondshire, Ryedale, Scarborough and Selby districts. Its sustainable drainage guidance was last updated in 2022.
• The national parks. The Yorkshire Dales and North York Moors National Park Authorities decide planning applications inside their boundaries, with their own local plans. The Peak District National Park Authority does the same on the moorland fringe of South and West Yorkshire.
• York, Hull and the East Riding. City of York Council, Hull City Council and East Riding of Yorkshire Council are each unitary, and Hull and the East Riding share the estuary and the Humber 2100+ work.
• West Yorkshire. Leeds, Bradford, Calderdale, Kirklees and Wakefield are five metropolitan councils, each its own flood authority.
• South Yorkshire. Sheffield, Rotherham, Barnsley and Doncaster work as four flood authorities, and with the Environment Agency and Yorkshire Water through the Connected by Water partnership.
• The Tees. Middlesbrough and Redcar and Cleveland work with the Northumbria flood committee and Northumbrian Water rather than the Yorkshire bodies.

On major development the flood authority is a statutory consultee on surface water, and its comments often decide whether an application is approved, delayed or refused. Our guide to the Lead Local Flood Authority and the note on statutory consultees explain the role. For sites in the Calder valley, our page on Calderdale Council's flood and drainage requirements sets out that council's rules in detail.

The local plans and SFRAs a Yorkshire application is read against

Each planning authority has its own local plan and Strategic Flood Risk Assessment, and in October 2026 several of them are being replaced. The table gives the plan in force, its flood and drainage policies where they were confirmed for this page, and the latest SFRA found. The Peak District National Park, which takes in only a moorland edge of South and West Yorkshire, is not listed.

Behind every local plan sits chapter 18 of the August 2026 NPPF: policy F4 sets when a site-specific assessment is needed, F5 and F6 cover the sequential and exception tests, and F8 expects all development to follow the 2025 National Standards for sustainable drainage. Our summary of the August 2026 changes covers what moved, and our explainer on what an SFRA is for shows how a council's assessment feeds into a planning decision.

Drainage standards that change from council to council

The national standards apply everywhere, but Yorkshire's councils still set their own discharge rates and floor levels, so a drainage strategy written for a Bradford site will not simply transfer to York. These are the local rules most often met:

• City of York. Policy ENV5 asks brownfield sites to cut runoff to 70% of the existing rate, with attenuation for at least the 1 in 30 year storm, and greenfield sites to discharge no more than they do now.
• Bradford. The 2023 SFRA sets greenfield runoff at 2 litres per second per hectare and asks for at least a 30% cut on brownfield sites that drain to a sewer.
• Leeds. The council's Minimum Development Control Standards for Flood Risk (June 2022) cut brownfield discharge by 30% on minor schemes and 50% on major ones where the existing connection is proven, and set 600 mm freeboard for homes above the design river level.
• Calderdale. The Flood Risk and Drainage SPD of July 2024 sets finished floors at the 1 in 100 year flood level with climate change, plus 300 mm freeboard for less vulnerable uses and 600 mm for more vulnerable ones.
• North Yorkshire. Its sustainable drainage guidance (2022 update) comes with supplementary guidance on infiltration testing.

Our ground conditions and soakaway checker gives a first read on whether infiltration is likely to work before any trial pits are dug, and our guide to the SuDS hierarchy explains the order in which outfalls are considered.

Does my Yorkshire site need a flood risk assessment?

Yes in Flood Zones 2 and 3, and on any site of a hectare or more in Flood Zone 1. Some Yorkshire councils go further, so for a small Zone 1 site the answer depends on where it is. The flood zones come from the Environment Agency; the local triggers come from each plan.

New homes in Flood Zones 2 and 3 also face the sequential test, which asks whether lower-risk land is reasonably available. Kirklees policy LP27 makes the whole district the starting point for that search unless a smaller area is justified, and the East Riding publishes its own supplementary planning document on the two tests. Our note on the September 2025 PPG update covers how the government's guidance on the test changed.

What we prepare for Yorkshire sites, Pennine valley to Humber bank

We prepare each of the reports below for sites across all four Yorkshire counties. They are written by chartered consultants and signed off by a senior consultant, and Unda is a CIWEM Business Partner.

• Planning applications. A scheme in Flood Zone 2 or 3, on a hectare or more, or in one of Calderdale's critical drainage areas needs a flood risk assessment for planning.
• Several sources on one plot. A flood risk assessment in Yorkshire often has to weigh a river, the tide, a reservoir and the drains together.
• Buying a home. Streets that flooded in 2007, 2015 or 2019 can prompt questions from a lender, which a flood risk survey for property purchase answers before exchange.
• New homes in the flood zones. A sequential and exception test shows whether lower-risk sites are reasonably available, searched across the area the council expects.
• Major schemes. The council's flood team reviews the drainage strategy for major development against its own rules and the national standards.
• Discharge rates. A surface water drainage strategy sets the rate, storage and route for runoff to the standard of the council that will review it.
• Conditions on a permission. Where a drainage condition was attached, we prepare what the council needs for the discharge of drainage conditions.
• Flooded streets and premiums. Owners in the Calder valley, Hull and Fishlake, where homes flooded in 2007, 2015 and 2019, can use a flood risk assessment for insurance to set out the current risk to their property.
• Freeport and employment land. Where commercial buildings on the Humber Freeport's Hull East and Goole tax sites are built to a BREEAM rating, a BREEAM flood risk assessment supports the flood risk credits.
• Industrial land on the estuary. Ports, works and warehouses on pumped land around the Humber call for flood risk due diligence before purchase or refinancing.
• Businesses with a flood history. Firms in Sheffield's Lower Don Valley, which flooded in June 2007, and in the Calder valley mill towns use a business continuity flood risk assessment to plan for the next event.
• The chalk Wolds. Where the Gypsey Race and other chalk springs break out, a groundwater flood risk assessment tests whether soakaways and basements will work.
• Main rivers without site levels. On the Ouse, Aire, Calder and Don, where the national mapping gives no level for the site, flood modelling provides one.
• Behind the Humber banks. Where a site in Hull, Goole or along the tidal Ouse depends on defences, a flood warning and evacuation plan sets out how people leave safely once a warning is issued.
• Land in new local plans. With new plans under way in North Yorkshire, Leeds, Bradford and Doncaster, a flood risk feasibility study tests land before it is promoted.
• Solar and energy schemes. The East Yorkshire Solar Farm, given development consent in May 2025 with a connection at Drax, shows the scale of energy schemes on the county's low ground; our renewable energy flood risk assessments cover solar, wind and biogas sites.
• National policy. Our NPPF flood risk guidance explains how chapter 18 works alongside the seventeen Yorkshire plans in the table above.

Yorkshire towns and cities with pages of their own

For a site in one of these places, its own page goes further into its rivers, its flood record and its council's policies:

• West Yorkshire. Leeds and Bradford on the Aire, Halifax in Calderdale and Huddersfield in Kirklees, and in the upper Calder valley Hebden Bridge and Mytholmroyd.
• South Yorkshire. Sheffield and Doncaster on the Don.
• The Ouse and the Humber. York where the Foss meets the Ouse, and Hull on the estuary.
• The Tees. Middlesbrough on the tidal river.

Beyond the county, our neighbouring county pages cover Lincolnshire across the Humber, County Durham across the Tees and Lancashire over the Pennines. Every other county and town page is on our list of the areas we cover.

Who to call about flooding in Yorkshire, from 999 to the drainage boards

Call 999 if anyone's life is in danger, and 105 if a flood has cut the power. Otherwise the right contact depends on where the water is coming from, and Middlesbrough and Redcar and Cleveland use different bodies from the rest of the county.

Questions people ask about a flood risk assessment in Yorkshire

From the Dales to Holderness, Unda Consulting Limited prepares flood risk assessments, sequential and exception tests and drainage strategies for Yorkshire sites. To discuss one, call 01293 214444 or email enquiries@unda.co.uk.