River Trent Flooding & Flood Risk

The River Trent is one of the great flooding rivers of England. It drains roughly 10,435 square kilometres of the Midlands — a catchment stretching from the Staffordshire moors to the Peak District and Charnwood Forest — and funnels all of that water through the towns strung along its banks, from Stoke-on-Trent and Burton upon Trent down through Nottingham and Newark to Gainsborough and the Humber. When the ground is saturated and the rain keeps coming, the Trent rises for days and spreads across a floodplain that has been settled, farmed and built on for centuries. Unda prepares flood risk assessments, drainage strategies and related reports for sites the length of the Trent floodplain. To talk a site through, call 01293 214444 or email enquiries@unda.co.uk.

During Storm Henk in January 2024, the Trent reached a record level north of Newark-on-Trent, beating the benchmark set in the great flood of November 2000 — and across the East Midlands that single spell of flooding put water inside 344 homes and 40 businesses.

• The third-longest river in Britain. The Trent runs about 185 miles (297 km) from its source on Biddulph Moor in Staffordshire to Trent Falls, where it joins the Yorkshire Ouse to form the Humber Estuary.
• A Main River almost end to end. The Environment Agency regulates the Trent as a Main River along effectively its whole length, so the 8 metre byelaw margin and Flood Risk Activity Permits apply to works near the channel.
• Tidal below Cromwell. Downstream of Cromwell Weir near Newark the Trent becomes tidal, and its lower reaches carry a genuine tidal bore — the Trent Aegir — as far as Gainsborough.
• Nine centuries of flood records. The Trent's documented flood history runs back some 900 years, and the largest events have repeatedly overwhelmed Nottingham, Burton, Newark and the villages of the lower valley.

Check flood risk along the River Trent

The map below draws the River Trent in coral, with the Environment Agency’s live river gauges positioned along its course — click a gauge to see its latest level, its typical range and its record peak. Enter a postcode near the river to zoom in and screen that location against the Environment Agency’s flood data for rivers and sea, surface water, reservoirs and the flood zones used for planning. It is an indicative screening tool, not a flood risk assessment.

Why does the River Trent flood?

The Trent floods because it collects the runoff of almost the entire north Midlands and delivers it, in sequence, through a chain of low-lying towns. Its catchment covers around 10,435 square kilometres and its biggest tributaries — the Tame out of Birmingham, the Derwent off the Peak District, the Soar from Leicestershire, the Dove and the Sow — each arrive within a short stretch of one another, so a wet spell over the wider Midlands stacks their peaks onto the main river at much the same time. The result is a river that rises steadily for days and stays high, rather than one that spikes and drops in hours.

The single largest contributor is the Tame, which drains the conurbation around Birmingham and can push nearly a quarter of the Trent’s total flow; the Derwent adds around 18 per cent, the Soar about 17 per cent and the Dove roughly 13 per cent. At Colwick on the eastern edge of Nottingham, the point where those inputs have combined, the river’s average flow is about 84 cubic metres a second — but in flood it has reached more than 1,000 cubic metres a second, and the recorded maximum at Colwick is 1,018 m³/s. Historically, the very worst floods have come when heavy rain has fallen on a deep snowpack and melted it fast, as in the catastrophic thaw of March 1947.

• A very large gathering ground. Around 10,435 km² of the Midlands drains to the Trent, so widespread rain produces a large, sustained flood rather than a brief spate.
• Tributaries that peak together. The Tame (~24% of flow), Derwent (~18%), Soar (~17%) and Dove (~13%) join within a relatively short reach, combining their peaks on the main river.
• Big gauged flows. Average flow at Colwick, Nottingham is about 84 m³/s; the recorded maximum there is 1,018 m³/s, and the average at North Muskham below Newark is higher again at about 88 m³/s.
• Rain on snowmelt is the worst case. Several of the largest historical floods, including March 1947, were driven by rain falling onto melting snow across the catchment.

A history of flooding on the River Trent

Few English rivers have a flood record as long or as well documented as the Trent’s. In Nottingham the heights of major floods since 1852 are carved into a bridge abutment beside Trent Bridge, with older marks transferred from the medieval Hethbeth Bridge that once crossed here. Those marks, and the gauge records that followed, let us rank the great floods of the valley — and they show that the biggest were bigger than anything in living memory.

The flood of February 1795 remains the largest on record. It came from a rapid thaw of deep snow and burst the flood bank at Spalford so violently that filling the breach took eighty loads of faggots and more than four hundred tons of earth. Eighty years later, the flood of October 1875 devastated the valley again: in Nottingham a cart overturned in the floodwater near Wilford Road and six people drowned, while at Burton upon Trent much of the town was inundated. The great snowmelt flood of March 1947 sent the Trent over its banks across Nottingham, affecting some 28 miles of road, around 3,000 properties and 86 factories in the city alone, and flooding the length of the valley.

The defining modern flood was November 2000, when a saturated autumn was followed by more heavy rain and the Trent produced the highest levels of the twentieth century’s later decades. It was that 2000 benchmark the river then beat, north of Newark, during Storm Henk in early January 2024, after one of the wettest autumn-to-winter periods on record left the ground unable to take any more. Across the East Midlands the winter storms of 2023–24 — Babet, Ciarán and Henk in succession — flooded 344 homes and 40 businesses and closed 69 roads, with 32 properties flooded internally in Newark alone.

Which areas does the River Trent put at risk?

Flood risk on the Trent is concentrated on the valley floor, and it changes character down the length of the river: flashy, urban headwater flooding around Stoke-on-Trent; broad floodplain flooding through Burton, Nottingham and Newark; and tidal flooding in the lower reaches around Gainsborough. The Environment Agency runs flood warning and alert areas the length of the river. The table below summarises the main settlements at risk from source to mouth.

If your site sits within one of these areas, the Environment Agency’s flood map for planning is likely to place it in Flood Zone 2 or 3, which triggers the need for a site-specific flood risk assessment. You can screen any address against the live Environment Agency data using the map above, and the towns along the river are covered in more depth on our local pages for Stoke-on-Trent, Nottingham, Newark-on-Trent and the wider counties of Staffordshire, Derbyshire, Nottinghamshire and Lincolnshire.

Is the River Trent tidal? The Trent Aegir

Yes — the lower Trent is tidal. Below Cromwell Weir, a few miles north of Newark, the river comes under the influence of the North Sea tide reaching up the Humber, and from that point downstream the flood risk is a combination of river flow and tide. When a high spring tide funnels into the narrowing river mouth it can raise a bore — the Trent Aegir, or Eagre — a wave up to about 1.5 metres high that travels upstream as far as Gainsborough. The Aegir is a spectacle in normal conditions, but the same tidal push is what makes flooding in the lower valley so serious when a high tide coincides with high river flow.

This tidal reach matters for anyone developing near the lower Trent, because a flood risk assessment there has to consider tide-locking — the situation where a high tide holds back the river and its tributaries, so land that seems safe on a purely fluvial view can still flood. The reach above Cromwell, by contrast, is controlled by weirs and locks and behaves as a purely river-fed system, where the question is how high and how long the freshwater flood runs.

Flood defences along the River Trent

Long stretches of the Trent are defended, and those defences shape what a flood risk assessment has to say. The largest is the Nottingham (Trent Left Bank) Flood Alleviation Scheme, a continuous line of walls and embankments running about 27 kilometres from Sawley in the west to Colwick in the east. Completed in 2012 at a cost of around £45 million, it reduces flood risk to roughly 16,000 homes and businesses and is the largest individual inland flood defence scheme in England by the number of properties it protects. Downstream at Burton upon Trent, the defences and washlands hold back flooding from around 7,000 properties, and both towns’ defences were reassessed and improved after the November 2000 flood.

• Defences do not remove risk. They are built to a design standard, and the Environment Agency’s flood map for planning deliberately shows the floodplain as if the defences were not there — so a defended site still sits in Flood Zone 3 and still needs its residual risk assessed.
• The whole left bank is one flood cell. Through Nottingham, the defended left bank behaves as a single unit; if it were overtopped or breached, the depth and speed of flooding behind it has to be understood, not assumed away.
• Washlands and storage. Along the middle Trent, low-lying washlands are allowed to flood deliberately to take the pressure off the towns, and building near them changes how they work.

Getting this right is the difference between an assessment that stands up and one the Lead Local Flood Authority rejects. A site behind a defence, or beside a washland, is not automatically safe: the assessment has to show what happens in the events the defences are not designed to hold.

Is the River Trent a Main River — and what that means for your site

Yes. The Environment Agency has designated the Trent a Main River along effectively its whole length, which means the Agency, rather than the local council, regulates the channel and its immediate margins. That distinction is not academic if you are developing nearby. Works within 8 metres of the top of the bank generally need a Flood Risk Activity Permit from the Environment Agency before they start, in addition to planning permission, and a site in the river’s floodplain will normally need a flood risk assessment. Many of the brooks and drains that feed the Trent are ordinary watercourses instead, regulated by the county council as Lead Local Flood Authority and by the riparian owners whose land they cross — and confirming which watercourse you are actually dealing with is one of the first things a good assessment settles.

• The 8 metre byelaw margin. Building, excavation or structures near the Trent usually require a Flood Risk Activity Permit, sought alongside — not instead of — planning permission.
• Flood zones drive the assessment. A site in Flood Zone 2 or 3, or a larger site in Flood Zone 1, needs a flood risk assessment for planning.
• Know your watercourse. The Trent itself is Environment Agency territory; its tributary brooks and ditches are usually ordinary watercourses under the Lead Local Flood Authority. We confirm this for every site.

Flood risk and drainage services for sites near the River Trent

A development near the Trent can call for several different reports, and it helps to be clear that they answer different questions. A flood risk assessment, a sequential or exception test and a drainage strategy are three distinct reports. They often travel together in a planning submission, but they address separate things: whether the site is safe from flooding, whether the development should be located here at all, and where the surface water goes. Unda prepares each of them for sites across the Trent catchment.

• Flood risk assessments for planning. Site-specific assessments dealing directly with the Environment Agency’s requirements for development in the river’s flood zones. See our flood risk assessment for planning service.
• Assessments for property purchase and insurance. Independent reports for buyers, owners and lenders through our flood risk survey for property purchase and flood risk assessment for insurance, useful given the Trent’s effect on mortgage lending.
• Drainage strategies and SuDS. Surface-water designs that meet the discharge limits set by the Lead Local Flood Authority — see our sustainable drainage strategy and preliminary drainage design services.
• Sequential and exception tests. Locational justification where policy requires it, through our sequential and exception test reports.
• BREEAM and specialist assessment. A BREEAM flood risk assessment for the Pol 03 credit, and, where national mapping is not enough, detailed hydraulic flood modelling and flood consequence assessment.

On a river this size, the national flood maps are often only a starting point. Where a site sits tight against the Trent or behind a defence, we can bring in hydraulic modelling to derive accurate flood levels, prepare the detail needed to discharge a drainage condition, and, in Stoke-on-Trent, we have seen how a scheme like the £12.6m Fowlea Brook works can unlock development once the flood case is made properly.

Managing flood risk on the River Trent: policy and contacts

Responsibility for flood risk on the Trent is shared. The Environment Agency regulates the Main River, publishes the flood map for planning, issues flood warnings and maintains the major defences; the county councils — Staffordshire, Derbyshire, Nottinghamshire, Leicestershire and Lincolnshire — are the Lead Local Flood Authorities for surface water, groundwater and ordinary watercourses; and the district and city councils decide planning applications, each guided by its own strategic flood risk assessment and by the Environment Agency’s River Trent catchment flood management planning. Knowing who does what saves time on any application near the river.

• Live river levels. Check the Trent’s gauges on the Environment Agency service — for example River Trent at Colwick, Nottingham — or use our own live river levels map.
• Screen a location. Try our free flood risk map, and for drainage design the drainage calculators, the BRE 365 infiltration calculator and the ground conditions and soakaway map.
• Understand the record. The station history at the National River Flow Archive for Trent at Colwick and the council’s Section 19 report on the Storm Henk flooding at Newark set out what happened and why.
• Flood warnings and emergencies. Sign up for Environment Agency flood warnings and call Floodline on 0345 988 1188. In a flood emergency call 999 if life is in danger, and 105 for power cuts.

How Unda helps with flood risk on the River Trent

Unda understand how the Trent behaves in flood — how the tributaries stack their peaks onto the main river, where the defended reaches at Nottingham and Burton change the residual-risk picture, and how the tidal lower river around Gainsborough combines river flow and tide. We know what the planning system and the Environment Agency expect from the reports that follow, and we prepare assessments and drainage strategies for developers, planning consultants, architects, agents and homeowners with sites the length of the valley.

Every assessment rests on the same evidence the regulators use: the Environment Agency’s flood mapping, the river’s gauged levels and modelled flows, and the local planning policy that applies to the site. If you are working on a site near the River Trent, talk to one of our experienced flood risk consultants about what your application will need.

River Trent flood risk: your questions answered