Flood Risk Assessment in Nottingham

Our team at Unda use years of experience to prepare comprehensive flood risk assessments and drainage strategies for commercial and residential sites across Nottingham. A flood risk assessment in Nottingham shows your local planning authority that a development will stay safe from flooding for its whole lifetime, without pushing flood risk onto anyone else.

Nottingham sits on the left bank of the River Trent, where the river runs along the southern edge of the city and gathers the Leen, the Day Brook, Tottle Brook and, further west, the Erewash. We assess every source that matters here — the Trent and its tributaries, the surface water that overwhelms drains across the built-up city, the groundwater that rises through the river-terrace sands and gravels, and the sewers that back up in heavy rain — then deal directly with the Environment Agency and Nottingham City Council on your behalf. We guide architects, planning consultants, developers, landowners, home buyers and businesses through to a decision, whether the report is needed for planning, a property purchase, mortgage or insurance, BREEAM, or a surface-water drainage strategy.

If you need a quote or want to talk a site through, contact one of our experienced flood risk consultants on 01293 214444.

The whole left bank of the Trent through Nottingham is a single defended flood cell, so much of the city sits behind flood defences in Flood Zone 3 — and because the planning map is drawn as if those defences were not there, the residual risk has to be read carefully or an assessment will not stand up to the Environment Agency or Nottingham City Council.

Flood risk assessment in Nottingham at a glance

• The Trent runs along the city's southern edge. The whole left bank through Nottingham is a single 27 km flood cell, defended from Sawley in the west to Colwick in the east, so a breach or overtopping anywhere on that line is what the risk is measured against.
• The Trent reached 5.36 m at Colwick in January 2024, just 15 cm short of the November 2000 record, when the Nottinghamshire Local Resilience Forum declared a major incident during Storm Henk.
• One Lead Local Flood Authority. Nottingham City Council is a unitary authority and the Lead Local Flood Authority for the city, responsible for surface water, groundwater and ordinary watercourses, while the Environment Agency leads on the Trent.
• Flood Zone 1 is not a free pass. Since the 2025 PPG update, surface water risk can trigger an assessment even on a Flood Zone 1 site.

Check flood risk anywhere in Nottingham

Nottingham is outlined below. Screen any postcode in the city against Environment Agency data for rivers and sea, surface water and the planning flood zones, with a climate outlook to 2125. It is an indicative first pass, not a substitute for a site-specific assessment.

Flood risk in Nottingham: the Trent, the Leen and surface water

River flooding from the Trent dominates Nottingham, but it is rarely the only source on a site. The Leen and Day Brook drain the north of the city, Tottle Brook runs through the west, and surface water now overwhelms drains across the built-up areas, while groundwater rises through the sands and gravels of the Trent valley. Most sites here face more than one source at once.

The Trent flows west to east along the southern edge of Nottingham, fed by the Erewash and the Soar upstream and by the Leen, Day Brook and Tottle Brook within the city. A wet spell across the wider catchment becomes a flood peak on the Trent a day or two later, which is why the riverside neighbourhoods have flooded repeatedly and why the city is now defended along its whole left bank. Understanding which watercourse drives the risk on a given site, and how it behaves, is the heart of a credible fluvial flood risk assessment.

• Rivers (fluvial). The Trent and its tributaries — the Leen and Day Brook in the north, Tottle Brook in the west and the Erewash on the boundary — flood the valley floor. Land in Flood Zones 2 and 3 along these corridors almost always needs an assessment.
• Surface water (pluvial). Now the most widespread flood risk in England. Intense rain overwhelms drains in the dense urban core and low-lying areas such as Lenton, Old Basford and the Meadows. Since the 2025 PPG update, surface water on the Flood Map for Planning can trigger an assessment even on a Flood Zone 1 site.
• Groundwater. The river-terrace sands and gravels of the Trent valley carry a shallow water table that can flood low ground and basements without ever showing on a river map — critical for any soakaway or below-ground level. See groundwater flooding.
• Sewers and ordinary watercourses. The Leen, Day Brook and the surface-water sewer network back up in heavy rain. These sit with the Lead Local Flood Authority rather than the Environment Agency — see the role the LLFA plays.

The Meadows is the textbook case for why a single map is never enough: the Trent floodplain runs hard against it, while the surrounding streets also take surface water that has nowhere to drain by gravity. A scheme there has to reconcile both. Our notes on the sources of flood risk and on surface water and planning set out how these sources interact, and our guide to pluvial flooding covers the urban detail.

A history of flooding in Nottingham

These dated events are why the authorities here scrutinise development so closely, and why a flood risk assessment in Nottingham has to be evidence-led rather than generic. Each one shaped the local flood defences a developer now has to design around.

• Recorded since 1683. Nottingham's flood record on the Trent runs back more than three centuries, long enough to show that the riverside parts of the city have always flooded in extreme events.
• 1947 — the great Trent flood. Snowmelt and rain in March 1947 sent the Trent over its banks across Nottingham, affecting around 28 miles of road, some 3,000 properties and 86 factories in the city. It remains the benchmark historical flood for the Trent through Nottingham.
• November 2000 — the modern record. The autumn 2000 floods produced the highest levels on record on the Trent, with the river rising several metres above normal and inundating low-lying ground. The event was a major driver of the flood defences that now protect the city.
• January 2024 — Storm Henk. The Trent peaked at 5.36 m at Colwick, about 15 cm short of the 2000 record, and the Nottinghamshire Local Resilience Forum declared a major incident as the Meadows, Colwick and riverside roads were threatened.

A pattern runs through all of it: ground that flooded once tends to flood again. A robust assessment treats this recorded history as evidence, not background colour.

Flood defences protecting Nottingham: the Trent Left Bank scheme

Major investment followed the 2000 floods, and the defences change what a development next to them has to prove. A defence reduces the chance of flooding, but it never removes it, and planning policy still expects the residual risk to be assessed.

• The Nottingham (Trent Left Bank) Flood Alleviation Scheme. Around £45 million of works that reduce flood risk to roughly 16,000 homes and businesses along a 27 km stretch of the Trent, from Sawley in the west to Colwick in the east — the largest individual inland flood defence scheme in England by the number of properties protected.
• One continuous flood cell. The whole left bank through Nottingham behaves as a single cell, so a breach at any point could in theory flood the area behind the defences. Embankments and walls were raised and strengthened through Victoria Embankment and the riverside parks.
• Funded and built for the long term. The scheme was funded by Defra and built by the Environment Agency with Nottingham City Council and local partners, but it was designed to a standard of protection, not to remove risk entirely.

The catch for developers is the one we set out in residual flood risk and why a site stays in a flood zone after defences are built: the Flood Map for Planning is drawn as if the defences are not there, so a defended site behind the Left Bank scheme can still sit in Flood Zone 3. A defence can also be below its design standard in practice, and communities increasingly have a role in maintaining local defences. Climate change makes this sharper still, which is why an assessment applies the Environment Agency's allowances over the development's lifetime.

Planning policy and your Lead Local Flood Authority in Nottingham

Two kinds of authority set the rules. The Environment Agency leads on the River Trent and the other main rivers. A Lead Local Flood Authority (LLFA) leads on surface water, groundwater and ordinary watercourses — and in Nottingham that is Nottingham City Council, a unitary authority responsible for the city in its own right, separate from Nottinghamshire County Council.

A developer here deals with Nottingham City Council as both the local planning authority and the LLFA, alongside the Environment Agency and the role the LLFA plays as statutory consultee on surface water drainage. Our overview of who manages flood risk in England explains how the pieces fit together, and for sites just beyond the city our flood risk assessment in Nottinghamshire page covers the wider county.

Your assessment and drainage strategy must satisfy national policy — the NPPF and its Planning Practice Guidance — and the local framework: Nottingham City Council's Local Flood Risk Management Strategy, the Strategic Flood Risk Assessment for Greater Nottingham, and the flood and drainage policies in the Greater Nottingham Strategic Plan. Where a higher-risk site is involved, the Sequential and Exception Tests apply, and the right vulnerability classification has to be argued. On drainage, the 2025 national SuDS standards and the four pillars of SuDS shape what the LLFA will accept.

What your flood risk assessment in Nottingham must show

• Risk assessed from every credible source, using the Flood Map for Planning and local data.
• An appropriate location, tested against the Sequential Test where policy requires it.
• Safe for its lifetime, once the climate change allowances are applied.
• No increase in flood risk elsewhere, with attenuation and, where needed, compensatory storage.
• Residual risk managed, with safe access, egress and finished floor levels set above the design flood level.

Development and flood risk assessment in Nottingham

Nottingham is regenerating fast, and the kind of site you bring forward shapes the assessment you need. The right scope is the difference between a clean approval and a drainage objection that holds an application up for months.

• Riverside and waterside regeneration. Schemes along the Trent, including the Waterside area, Trent Basin and the wider eastside, frequently sit in Flood Zones 2 and 3 behind the Left Bank defences, needing finished floor levels, safe access and egress, and often compensatory flood storage.
• City-centre brownfield infill. High-density redevelopment across the centre, including the Island Quarter and the Broadmarsh area, turns on surface water and drainage because almost every surface is already impermeable.
• Student and build-to-rent housing. The two universities drive dense residential schemes where the vulnerability classification and safe-access case have to be argued carefully on constrained city sites.
• Employment and logistics land. Larger sites towards Colwick and the city fringe carry extensive impermeable area, which makes the surface-water drainage strategy central to the application and to the right reading of the flood sources.

Climate change is not optional here. A Nottingham assessment must apply the Environment Agency's allowances for higher river flows and rainfall over the development's lifetime — generally 100 years for housing — which sets floor levels, freeboard and how much attenuation a drainage scheme needs.

Home buyers and businesses come to us too. A flood risk question can affect a purchase and house prices, and a conveyancing search is not the same thing as a planning-grade assessment. Knowing which you actually need saves time and money, and our note on the flood zones explains where the line falls.

How Unda helps with flood risk assessment in Nottingham

We act as the accurate translation layer between your scheme and the requirements set by the Environment Agency, Nottingham City Council and national planning policy. We are experts on the city's flooding, not a generic report mill.

A flood risk assessment in Nottingham from Unda assesses every credible source — the Trent and its tributaries, surface water, groundwater, sewers and any ordinary watercourse on the boundary — compares modelled flood levels against your proposed floor levels, sets safe access and egress, and recommends mitigation the regulators will accept. We are a CIWEM Business Partner with chartered members, and a senior consultant signs off every report. Where the council needs it, a surface-water drainage strategy sits alongside the assessment as a separate report so the two cases stay consistent and an objection has nowhere to land.

Flood risk assessments and related reports for every situation in Nottingham

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 answer different questions: is the site safe, should the development be here, and where does the surface water go. We prepare all three, alongside the right form of assessment for buyers, lenders and BREEAM.

Flood risk assessments

• Flood risk assessment for planning. The core report, site-specific and prepared to satisfy the NPPF, the Environment Agency and Nottingham City Council. Groundwater and, where needed, flood modelling are assessed within it rather than as separate reports.
• Homebuyer and property-purchase survey. For conveyancing, where a search has flagged Trent-side or surface-water risk and you need the actual building assessed, not a broad map.
• Flood risk assessment for insurance. Property-specific evidence for brokers and underwriters where premiums have risen or cover has been restricted, as record flood claims push prices up.
• Flood risk assessment for BREEAM. Structured around BREEAM Pol 03, which is credit-driven rather than safety-driven, so a planning assessment alone rarely satisfies it.
• Groundwater flood risk. A defensible design water table for Trent-valley gravel sites and any basement — assessed as a source within the assessment, or as a standalone hydrogeological study on complex sites.

Sequential and Exception Tests

The Sequential and Exception Tests are a separate, locational report about whether a development should be in a higher-risk location at all. The Sequential Test defines an area of search, identifies reasonably available lower-risk sites and justifies the proposed site; the Exception Test is the second gate where development still needs to proceed. A clean site-specific assessment showing the development is not actually within an area at risk can remove the need at application stage — a live policy area, as our note on what the Yatton judgment means for planning explains.

Drainage strategy and SuDS

• Sustainable drainage strategy (SuDS). Surface-water engineering — calculates existing versus proposed runoff and proposes SuDS to hold discharge within the rates the LLFA will accept.
• Preliminary drainage design. The early, outline read that flags infiltration issues before they affect layout and land value.
• Discharge of drainage conditions. The detailed stage to discharge a pre-commencement or pre-occupation drainage condition.
• Flood modelling. 1D and 2D hydraulic modelling — a technique that feeds the assessment, Sequential Test or drainage design where national mapping is not enough.

Early in a drainage strategy it helps to know whether the ground will take water: our free geology and ground conditions map and BRE 365 infiltration rate calculator give an indicative read before a trial pit, and the drainage calculators help size the scheme. You can screen a postcode on our flood risk map, and every report is overseen by a chartered flood risk consultant who stays involved past the report to answer objections.

Nottingham flood resources and contacts

The most reliable Nottingham flood information comes from the lead authorities. For an immediate threat to life during a flood, always call 999; for a power cut during flooding, call 105.

• Check for flooding in Nottingham. Environment Agency live warnings, river levels and maps at check-for-flooding.service.gov.uk; sign up for flood warnings or call Floodline on 0345 988 1188.
• Nottingham City Council flooding. Report flooding, and find the Local Flood Risk Management Strategy and developer guidance, at nottinghamcity.gov.uk.
• Greater Nottingham Strategic Plan. The flood and drainage policy framework and Strategic Flood Risk Assessment evidence at gnplan.org.uk.
• Trent Regional Flood and Coastal Committee. Regional investment and priorities via the Trent RFCC.
• Sewer flooding. Severn Trent Water is the sewerage undertaker for Nottingham; report sewer flooding to them directly.
• Live river levels. Whether the Trent or Leen are running high right now via our live river levels map.

For broader policy context, our notes on the Environment Agency's planning role and on urban surface water risk are a good starting point.

Flood risk assessment in Nottingham: frequently asked questions