Fens 2100+: flood risk management is reaching its limits – and the Fens show why
Estimated reading time 7 minutes
The Fens 2100+ reports set out one of the clearest assessments yet of flood risk, drainage and water management in England. They do not introduce a new problem, but they quantify one that has been building for decades.
Fens 2100+ is the Environment Agency’s long term flood risk and water management strategy for the Fens, developed with partners including Internal Drainage Boards and local authorities.
The Fens are often described as being at risk of flooding. That does not quite capture it. Much of the landscape only functions because water is actively managed through a network of drains, embankments, sluices and pumping stations.
Emma Jeffery, Senior Flood Risk Consultant at Unda, notes that "the Fens are not just exposed to flood risk. They depend on active flood and water management every day, across a very complex system."
That is the starting point. Fens 2100+ is not just about flood defence. It is about whether the current model of flood risk management and drainage can continue to perform under increasing pressure.
What is Fens 2100+?
Fens 2100+ is a long term partnership programme led by the Environment Agency, bringing together Internal Drainage Boards, local authorities, water companies and other stakeholders.
The Fens 2100+ Partnership describes its role as "transforming the approach to investing in flood and coastal resilience for the future of the UK Fens".
That focus on partnership reflects the structure of the system. Responsibility for flood risk and drainage is split across multiple organisations, and no single body controls how the system operates as a whole.
The programme publishes a shared evidence base to guide long term decisions on flood risk, drainage infrastructure and investment. The official GOV.UK material states: "The existing approach to managing water, flood, and coastal risks is no longer sufficient"
Why flood risk in the Fens is different
The Fens are one of England’s most engineered landscapes.
The summary baseline report shows:
- 4,333km² of low lying land
- more than 600,000 people
- 17,000+ flood risk and water management assets
- 318 pumping stations and around 4,500km of watercourse
Around 87% of the Fens sits below mean sea level, with some areas significantly lower.
The baseline report is clear - "Without critical flood risk management assets, the Fens would quickly flood and become uninhabitable."
Flood risk here is not just about where water goes during a storm. It is about whether the system can keep managing water continuously.
That is why catchment behaviour matters as much as site conditions, as explored in spongy landscapes and flood risk.
Emma explains "In the Fens, the issue is not just whether water reaches a site. It is whether the wider system can keep managing water as conditions change."
Flooding still happens in defended landscapes
The Fens 2100+ baseline report includes a historic flood timeline that shows how often flooding has occurred despite extensive defences.
Historic flood events in the Fens
- 1947 - snowmelt flooding affecting 85km² of agricultural land
- 1953 - tidal surge causing fatalities along the east coast
- 1978 - flood defence failure in Boston
- 2013 - tidal surge breaching embanked defences
- 2019 - Steeping River breach flooding 88 properties
- 2023 - Storm Babet causing widespread fluvial and surface water flooding
More recent events are just as important. In 2024 and 2025, heavy rainfall led to the highest recorded water levels in parts of the system.
Emma notes that "there is sometimes an assumption that defended means safe. The Fens record shows it is more complicated than that."
This is consistent with wider issues around below standard flood defences and why areas can remain in a flood zone after defences are built.
The timeline is becoming more difficult
The "now and next" timeline in the baseline report sets out how pressure on the system is increasing.
Recent system stress
- 2023 to 2024 - wettest winter on record, assets pushed "to their limits and beyond"
- January 2025 - highest recorded water levels in the South Forty Foot Drain
Future pressures
- 2040 - 31% of assets reach end of life
- 2075 - 89% of assets reach end of life
- 2080s - river flows increase by 4% to 21%
- 2125 - sea level rise of 1.2m to 1.6m
The official material states "Climate change will increase the frequency and severity of flooding in the Fens"
Emma highlights the issue: "The system works because it is managed intensively. As conditions change, that becomes harder to sustain."
Why the current flood risk model is under pressure
Flood risk management in the Fens has historically focused on maintaining and upgrading individual assets.
That approach is increasingly under strain for several reasons.
Ageing infrastructure
Many assets date back to post war investment periods and are now reaching the end of their design life.
Reduced gravity drainage
Sea level rise and land subsidence reduce opportunities for gravity discharge, increasing reliance on pumping.
System interdependency
The system behaves as a network. Decisions in one area affect water levels elsewhere.
This is why organisations such as Internal Drainage Boards play a central role, as explored in why Internal Drainage Boards matter for planning, alongside the wider framework of main rivers and ordinary watercourses.
Emma notes "As the system becomes more interconnected, managing assets in isolation becomes less effective."
What Fens 2100+ changes
Fens 2100+ shifts the focus from asset by asset management to system level planning.
It emphasises:
- shared evidence across organisations
- coordinated investment
- long term planning alongside short term resilience
It also recognises that engineering alone is not enough. Natural processes and land management play a role, but within limits.
This aligns with wider findings on natural flood management and the importance of soils and flood resilience.
Emma summarises "This is about making better decisions across the whole system, not just maintaining individual assets."
What this means for planning and development
For planning, the implications are practical.
Flood risk depends on how the system performs over time, not just current mapping.
Policy and decision making
Planning tools such as the Sequential and Exception Tests require consideration of future risk, not just present conditions.
This is reflected in case law and guidance, including applying the Sequential Test post-Mead and the Gladman judgment.
Technical evidence
Understanding flood risk at site level often requires detailed technical input, including:
In practice, a robust Flood Risk Assessment for planning and a well evidenced surface water drainage strategy are essential to demonstrate long term resilience.
Why this matters beyond the Fens
The Fens are unusual, but the pressures identified in Fens 2100+ are not.
Across England, flood risk systems face:
- ageing infrastructure
- increasing rainfall intensity
- greater surface water risk
- more complex governance
The Fens make these issues visible because the system is so dependent on active management.
Emma’s final view is measured; "There is no immediate failure. But the current approach becomes harder to sustain without long term planning. The decisions made now will shape how manageable flood risk is in the future."
Fens 2100+ is not a warning about a single location. It is an indication of how flood risk management is changing — and where its limits are starting to show.
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