Flood Risk Assessment Nottingham

Flood Risk Assessment Services in Nottingham

Nottingham’s position on the River Trent, one of England’s largest and most significant rivers, defines the city’s relationship with flood risk. The Trent’s vast catchment drains much of the Midlands, and the river’s floodplain through Nottingham is extensive, placing substantial areas of the city within Flood Zones 2 and 3. Combined with the River Leen, Tottle Brook, Day Brook, and extensive surface water risk, Nottingham presents a complex flood risk environment that demands expert assessment.

Aegaea provides specialist flood risk assessment, hydraulic modelling, and drainage consultancy services across Nottingham and Nottinghamshire. Our team has detailed knowledge of the Trent’s flood behaviour, the Environment Agency’s flood defence infrastructure, and the specific requirements of both Nottingham City Council and Nottinghamshire County Council as Lead Local Flood Authority.

Nottingham’s Flood Risk Landscape

The River Trent

The River Trent dominates Nottingham’s flood risk profile. With a catchment area of approximately 10,400 square kilometres upstream of Nottingham, the Trent receives flows from major tributaries including the Dove, Derwent, Soar, and Erewash before reaching the city. This vast contributing area means that Nottingham is vulnerable to widespread rainfall events across the Midlands, with flood peaks typically arriving 24 to 48 hours after the heaviest rainfall.

The March 1947 floods remain the benchmark event for the Trent at Nottingham. Snowmelt combined with heavy rain generated an enormous flood that inundated vast areas of the Trent valley, causing devastating damage across the East Midlands. The 1947 event led directly to the construction of flood defences along the Trent through Nottingham, defences that have been progressively upgraded and extended since.

More recent significant events include the autumn 2000 floods, when sustained rainfall across the Midlands brought the Trent to high levels, causing flooding in undefended areas, and the November 2012 event, which tested the recently completed sections of the Nottingham Left Bank Flood Alleviation Scheme. The July 2007 summer floods, while primarily driven by surface water across Nottinghamshire, also caused significant fluvial flooding on the Trent’s tributaries.

The Trent floodplain through Nottingham extends from Beeston and Attenborough in the west through The Meadows, Colwick, and Netherfield to the east. This broad floodplain, while providing natural flood storage, places extensive areas of developed land at risk. SEPA equivalent EA flood maps show Flood Zones 2 and 3 covering significant portions of the south side of the city, including major development and regeneration areas.

The Nottingham Left Bank Flood Alleviation Scheme

The Nottingham Left Bank Flood Alleviation Scheme (FAS), completed in stages between 2012 and 2018, represents one of the Environment Agency’s most significant flood defence investments in the Midlands. The scheme provides protection to approximately 16,000 homes and 2,400 businesses on the north (left) bank of the Trent, from Sawley and Long Eaton in the west through to Colwick and Stoke Bardolph in the east.

The scheme includes raised flood walls, earth embankments, flood gates, and pumping stations, designed to protect against a 1 in 100 year (1% annual probability) flood event. The design standard accounts for climate change over the scheme’s design life, though the actual allowance applied at the time of design may differ from current EA climate change guidance.

For developers working within the defended area, the Left Bank FAS significantly influences the flood risk assessment approach. While the defences reduce the probability of flooding, they do not eliminate risk entirely. FRAs must assess the residual risk from events exceeding the design standard, including the consequences of defence overtopping and breach. The EA’s breach modelling for the Nottingham defences provides data on predicted flood depths, velocities, and timing in the event of defence failure, and this data informs finished floor level recommendations and the design of flood resilience measures.

The River Leen and Smaller Watercourses

The River Leen flows southward through the western and central parts of Nottingham, passing through Bulwell, Basford, Radford, and the city centre before joining the Trent near Nottingham Station. Much of the Leen through the city centre is culverted beneath the streets, and the limited capacity of these culverts creates a risk of surcharging during intense rainfall events.

The Leen has historically been a significant source of flooding in Nottingham. The city centre is partially built over the Leen’s former course, and surface water flooding in the Broadmarsh, Lace Market, and Station Street areas can be linked to the culverted watercourse exceeding its capacity. The Environment Agency has undertaken modelling of the Leen to understand these interactions, and development proposals near the Leen’s course require assessment of culvert capacity and surcharge risk.

Other significant watercourses in Nottingham include the Tottle Brook, which flows through the southern suburbs including Clifton and Wilford; Day Brook, which drains the northern suburbs toward the Trent; and Fairham Brook, which flows through the major housing allocation area at Fairham Pastures south of Clifton. Each of these watercourses presents specific flood risk challenges for adjacent development.

Surface Water and Sewer Flooding

Surface water flooding is a significant and growing risk across Nottingham. The city’s mixed topography, with elevated areas to the north and west draining to the Trent valley, creates natural flow paths that concentrate runoff during intense rainfall. The urban environment’s impermeable surfaces, combined with ageing drainage infrastructure, exacerbate the problem.

The July 2007 summer floods were primarily a surface water event across Nottinghamshire, with intense convective rainfall overwhelming drainage systems and causing widespread flooding in areas remote from rivers. This event highlighted the vulnerability of Nottingham’s drainage network to extreme rainfall and prompted significant investment in surface water flood risk mapping and management.

Nottinghamshire County Council, as the Lead Local Flood Authority, has produced a Local Flood Risk Management Strategy and Surface Water Management Plan that identify areas at greatest surface water risk across the county, including numerous locations within Nottingham. These documents inform planning decisions and drainage design requirements for new development.

Planning and Regulatory Framework

NPPF and Planning Practice Guidance

Development in Nottingham is governed by the NPPF and Planning Practice Guidance on flood risk. The Sequential Test is a critical consideration for many Nottingham developments, given the extent of Flood Zones 2 and 3 along the Trent corridor. Where development in flood risk areas is necessary, the Exception Test requires demonstration of wider sustainability benefits and that the development will be safe over its lifetime.

Nottingham City Council’s planning policies, set out in the Local Plan and supporting documents, include specific requirements for flood risk assessment and drainage. The council works closely with the Environment Agency and Nottinghamshire County Council to ensure that flood risk is appropriately addressed in planning decisions.

Nottingham City Council SFRA

Nottingham’s Strategic Flood Risk Assessment provides the flood risk evidence base for the Local Plan. The SFRA identifies flood risk from all sources across the city, including climate change impacts, areas benefiting from defences, and functional floodplain. It informs the Sequential Test process and guides the location of new development.

The SFRA includes detailed mapping of flood risk that goes beyond the Environment Agency’s published flood maps, incorporating climate change scenarios, breach analysis for the Left Bank FAS, and surface water flood risk data. This makes it an essential reference for any flood risk assessment in Nottingham.

Lead Local Flood Authority Requirements

Nottinghamshire County Council, as the LLFA, is a statutory consultee on surface water drainage for major planning applications. The county council’s SuDS guidance sets out requirements for drainage strategies, including greenfield runoff rate restrictions, SuDS design standards, and long-term management and maintenance arrangements.

The LLFA expects drainage strategies to demonstrate that all surface water runoff from the development site will be managed through SuDS, with discharge rates restricted to greenfield rates for all events up to and including the 1 in 100 year plus climate change event. Where infiltration is feasible, it is encouraged as the preferred disposal route, but Nottingham’s geology (a mixture of Sherwood Sandstone and Mercia Mudstone) means that infiltration rates vary significantly across the city.

Key Development Areas in Nottingham

Southside and the Station Area

The Southside regeneration area, centred on the area south of the city centre between the railway station and the Canal, represents one of Nottingham’s most significant development opportunities. Parts of the area fall within Flood Zones 2 and 3, and development proposals must address fluvial risk from the Trent, the culverted Leen, and surface water. The Broadmarsh area redevelopment has required detailed flood risk assessment addressing these multiple sources.

The Meadows and Trent Bridge

The Meadows, a residential area on the south side of the city centre between the Trent and the canal, lies within the Trent floodplain and benefits from the Left Bank FAS. Development and regeneration proposals in The Meadows must assess residual risk from defence overtopping and breach, and finished floor levels must be set above predicted breach flood levels.

Colwick and Stoke Bardolph

The eastern Trent corridor through Colwick and Stoke Bardolph includes significant brownfield regeneration opportunity, including the former Colwick Industrial Estate. The area falls within the Trent floodplain and benefits from the Left Bank FAS in some locations. Development proposals require detailed assessment of fluvial risk, including breach analysis where relevant, and surface water management to avoid increasing downstream risk.

Fairham Pastures and Southern Growth

The major housing allocation at Fairham Pastures, south of Clifton, involves development on greenfield land within the Fairham Brook catchment. While the site is outside the Trent floodplain, the Fairham Brook and its tributaries present fluvial risk, and surface water management is critical to protect both the development and downstream areas. The scale of the development (potentially over 3,000 homes) means that a comprehensive drainage strategy incorporating strategic SuDS is required.

Bulwell, Basford, and Northern Corridors

Development sites in Nottingham’s northern suburbs, including regeneration areas along the River Leen corridor through Bulwell and Basford, face flood risk from the Leen and its tributaries. The culverted sections of the Leen through these areas create specific surcharge risks that must be assessed, and SuDS design must account for the limited downstream capacity.

Aegaea’s Nottingham Services

Aegaea provides comprehensive flood risk and drainage services across Nottingham and Nottinghamshire, including desktop and detailed flood risk assessments for planning applications, hydraulic modelling of the Trent, Leen, and smaller watercourses, breach and overtopping analysis for the Left Bank FAS and other defences, Sequential Test and Exception Test assessments, surface water drainage strategies and SuDS design, Environment Agency and LLFA pre-application consultation, and expert witness services for planning appeals.

Our understanding of the Trent’s flood behaviour, the Left Bank FAS, and the regulatory requirements of the EA, Nottingham City Council, and Nottinghamshire County Council means we deliver authoritative, efficient assessments that support successful planning outcomes. We work with developers, landowners, architects, and planning consultants across the city and wider county.

Contact Aegaea

If you are planning a development in Nottingham and need a flood risk assessment, drainage strategy, or Sequential Test assessment, contact Aegaea. Our team can advise on the likely scope of work and help you navigate Nottingham’s flood risk and drainage requirements from the earliest stages of your project.