Introduction to Welsh flood and coastal erosion policy

Louis Ramirez
Jan 1
9 min read

This explainer is written for flood action groups, other civil society actors, politicians and policy makers.

It offers a complete introduction to flood and coastal erosion risk management (FCERM) in Wales: the nature and drivers of the risk, the policies in place to manage it, and the system that governs it.

Prefer to read offline? The full briefing is available to download as a PDF below.

Flood risk: its sources and measurement

The different kinds of flooding

Flooding happens when the systems that move water away from homes, businesses and infrastructure are overwhelmed. The main types are:

Surface water — the land’s capacity to absorb or carry water away is exceeded.
Rivers — water bursts a river’s banks.
Coastal — storms and tides push water inland.
Sewer — sewer capacity is exceeded.
Groundwater — the water table rises, pushing water up through the ground.

Policymakers also distinguish “internal” flooding (water entering a home) from “external” flooding (gardens), and separately assess impacts on commercial buildings and critical infrastructure such as roads.

Coastal erosion refers to the loss of land to the sea.

How flood risk is measured

Risk severity is likelihood multiplied by impact. Two families of metrics are used.

Exposure metrics gauge the probability of flooding:

Floodplain population (FP) — potential exposure in a neighbourhood with no defences.
Expected Annual probability, Individual (EAI) — an individual’s average annual exposure, accounting for defences.
People Exposed to Frequent Flooding (PEFf) — people flooded more often than once in 75 years on average.

Risk metrics combine likelihood and severity:

Expected Annual Damage (EAD) — average annual direct economic damage, accounting for defences.
EAD: individual (EADi) — average economic risk to an individual in the floodplain.
Relative Economic Pain (REP) — uninsured damages as a ratio of household income.
Social Flood Risk Index (SFRI) — combines exposure, vulnerability and probability, at neighbourhood and individual level.

The human impact

Macro metrics miss lived reality. Beyond drowning, infection and injury, flooding carries longer-term health harms, including respiratory illness from mould.

Mental-health effects are widely acknowledged but under-studied. England’s National Study of Flooding and Health found that one year on, around 20% of those affected experienced depression, 28% anxiety and 36% PTSD.

Flood risk in Wales today

In its 2024–25 annual report, Natural Resources Wales (NRW) records 274,000 undefended residential properties at risk of flooding, of which 117,000 are at high risk. By source:

Source	Residential	Non-residential	Key services	Total
Rivers	91,102	12,630	2,745	106,477
Sea	80,281	9,439	1,987	91,707
Surface water & small watercourses	127,076	13,627	3,549	144,252

On the economic side, the think tank Public First estimates flooding causes £320m of damage a year in Wales — disproportionately high relative to Wales’ share of the UK population.

What is driving the risk

Climate change

FCERM professionals link the rising frequency and intensity of storms to climate change: burning fossil fuels raises global temperatures and shifts weather patterns.

Two documents anchor UK planning — the Met Office’s UK Climate Projections (UKCP18) and the Climate Change Committee’s risk assessment (CCRA3).

Land use and development

A more visible driver is land use: building, paving over absorbent ground, uncleared ditches and compacted farm soil all reduce the land’s capacity to hold water, so rain runs off faster and overwhelms river and surface-water channels.

Urbanisation tends to raise the peak flow of rivers and piles extra pressure on existing drainage.

In 2024 the National Infrastructure Commission for Wales commissioned JBA Consulting to quantify development’s impact. It found that “there exists no reliable nationally consistent monitoring data for development consents in the floodplain”, despite policies to that end.

As of October 2025 this review found no recent studies on the impact of upland farming on flood risk in Wales — an open question, and a particular concern for some downstream communities.

How exposure could change by 2120

Figures below are from NRW’s 2024–25 annual report. Two caveats apply.

First, it is unclear how far the modelling captures urbanisation and land-use change versus climate alone. Second, rising property counts tell only part of the story — they don’t capture how often, or how severely, those properties would flood.

Total properties & services at risk	2025	2120	Change
Rivers	106,477	130,969	+23%
Sea	91,707	131,501	+43%
Surface water & small watercourses	144,252	192,753	+33%

The coast is the sharpest concern: with around 60% of the Welsh population living on the coast, sea flooding shows the steepest projected rise.

Tools and strategies for reducing flood risk

Public debate often pits options against each other — calls to “dredge the rivers”, advocacy for “natural” over “grey” solutions, the celebration of woodland schemes, or a focus on property-level resilience.

Expert consensus, though, favours an “all of the above” approach, with methods working together at the right catchment scale. No single tool is a silver bullet for funding, governance or strategic gaps.

Two philosophies: safety vs. resilience

“Community resilience and behaviours” is one of five objectives in the Welsh Government’s 2020 strategy. In Wales, resilience is meant to stand alongside prevention; the wider UK trend is for resilience to take precedence over, or replace, prevention.

“Resilience” is also used loosely — often interchangeably with “safety”. In its technical sense it spans four ideas:

Concept of resilience	What it means	Relevant approaches
Resistance	Protect against hazards	Building and maintaining flood and erosion defences
Bounce-back	Recover to normal	Clearing up, repairing properties, rebuilding as before
Adaptation	Adjust to a new normal	Adapting properties so flooding causes less damage; accepting some fields will flood
Transformation	Own the need for big change	A community on a rapidly eroding coast deciding to relocate

Importantly, no UK government has yet adopted a measure of resilience — so there is almost no information on how resilient any given place actually is.

Engineered (“grey”) defences

Walls to keep water out, reservoirs to hold it back, and channels to direct it — often called “grey” infrastructure because of the concrete involved.

Property flood resilience (PFR)

Measures such as anti-flood air bricks and gates, non-return valves to stop sewage backing up, and changes that make homes quicker to repair.

PFR is contentious on two fronts: effectiveness and affordability. Governments fund engineered defences, but individuals usually pay for PFR, with grants covering only a little.

In 2018, academics working with insurers found that performance estimates rest largely on expert judgement for lack of real-world data. Defra’s 2023 assessment found uptake rose, but 37% of those who installed measures found them wanting — mostly because water entered by other routes — and the measures need regular maintenance.

Natural flood management (NFM)

NFM restores or enhances catchment processes to hold water back and reduce the volume reaching channels. Many schemes perform well but tend to be small-scale.

A 2017 Royal Society review stressed significant uncertainty about different interventions and the need to test whether models extrapolate to larger catchments.

The Environment Agency’s 2025 summary states with “medium confidence” that river restoration can slow flow and reduce downstream peaks — most effective across whole reaches and in smaller catchments. It adds, with “medium to high confidence”, that woodland restoration can cut peak flows, with the largest reductions for smaller events.

Dredging

Most often used to drain low-lying farmland and to aid navigation. It has fallen out of favour with UK policymakers on cost and environmental grounds.

It remains popular with parts of the public, though; floods are frequently followed by calls to dredge, which can reverse policy — as in Somerset after the 2014 floods (the area hasn’t flooded since, though nor has it had the same rainfall). The expert view is that dredging suits some cases and not others.

Warnings, response and recovery

Flood warnings let people act — moving to safety, protecting belongings.

During an event, emergency services prioritise safety, food, water, shelter, public order and essentials such as medicine; in England and Wales this runs through local resilience forums.

Afterwards, recovery needs money: government recovery grants, and — the main UK route — private insurance, a form of “anticipatory financing”. Where floods are caused by a company or individual (for example water companies and sewer flooding in England), compensation runs through the courts.

Long-term recovery support embeds experienced responders in communities for months, helping people through insurance, safety, mental health and much else.

How flooding is governed in Wales

Legislation

The main law is the Flood and Water Management Act 2010, amended in 2016 by the Environment (Wales) Act, which created the Flood and Coastal Erosion Committee — an expert body that advises government.

Policy

Wales’ second National Strategy on FCERM (2020) aims “to reduce the risks to people and communities from flooding and coastal erosion”, set out under five aims and objectives.

Who does what

Most environmental and planning policy is devolved. The Welsh Government holds national responsibility, with NRW responsible for general supervision and communication.

There are 22 Lead Local Flood Authorities. As of 2020 there were 28 Risk Management Authorities (RMAs): NRW, the 22 LLFAs, four water companies, and the Welsh Government in its highways role. The distributed nature of these duties produces many overlapping plans that flooded residents may have to navigate.

Money and devolution

NRW’s funding is allocated by the Welsh Government, which receives a Westminster block grant set largely by the Barnett formula; Wales can also raise limited devolved taxes and borrow for capital spending.

Capital schemes

For 2025–26 the Welsh Government’s FCERM Programme allocates £36m of capital funding — £22m to NRW and £14m to local authorities — expected to benefit 4,640 properties, part of a 2021 aim to reduce risk for 45,000 properties.

Water companies

Several water companies are RMAs, regulated economically by Ofwat (whose role is under review) and overseen by NRW.

What the government is working on

Bolstering community participation in flood risk management.
New ways to raise funds, such as land-value levies.
Fixing the skills shortage, with industry and universities.
Integrating flood work with broader climate-adaptation legislation.
Rolling out a catchment-based approach.

Is Welsh FCERM effective?

This section mainly reports recognised experts’ criticisms — from the Flood and Coastal Erosion Committee, Audit Wales, Senedd committees and academics — rather than our own. Because the systems are comparable, some English findings can be cautiously extrapolated to Wales.

Does it actually reduce risk?

The government can’t fully answer this — partly for good reasons.

Risk is likelihood times impact, but while government has likelihood assessments, Audit Wales notes it lacks an assessment of the damages floods would cause. So it has no baseline severity to measure progress against (it intends to change this).

The risks also keep moving: development or new defences in one part of a catchment can displace risk elsewhere, and climate change shifts the picture. And the National Infrastructure Commission for Wales has found no reliable, nationally consistent monitoring of development consents in flood-risk areas.

Is it adequately funded?

Capital spending sits around £33m a year and is set to dip slightly. NRW’s own analysis says this is insufficient to contain climate-driven risk and maintain current protection, though it suffices to protect the 100 most at-risk communities.

The main benchmark is NRW’s Long-Term Investment Requirements (LTIR), which models four scenarios:

Scenario	What it delivers	Cost / year
A — keep pace with climate change	Raise defence levels across Wales, no financial limit	£50m
B — economic assets only	Keep pace only where economically viable	£22m
C — focus on most at-risk	Keep pace at the top 100 communities	£23.8m
D — hold current funding constant	Maintain all assets; keep pace as far as funding allows	£19.7m

Audit Wales records actual capital funding varying between £26.6m and £33.6m, with the 2021–22 peak (£33.0m) boosted by repair money after the December 2020 and January 2021 floods — in other words, spending somewhere between Scenarios A and B.

Flooded People UK’s view: benchmarks like LTIR can be trusted only to a point.

Models can’t foresee shocks such as the post-2021 inflation surge, and granular local climate modelling is hard, risking under-estimated damages.

The modellers also aren’t independent — NRW is an arm’s-length body accountable to elected officials — and experience with the Environment Agency in England, and with water-pollution campaigners, raises real questions about whether such bodies will publish uncomfortable findings.

What is holding it back, according to the auditors?

Skills shortage. Audit Wales calls workforce capacity “the biggest issue facing the flooding sector” in the short term, limiting community engagement, collaboration, innovation and evidence-gathering for nature-based solutions.
Weak integration. Fragmented policy and funding restrict collaboration between RMAs, other public services and the private sector; agriculture and planning are flagged as key areas to join up.
State of defences. Many bodies and landowners maintain different assets, and NRW’s database excludes privately owned defences — so their real level of protection is unclear.
Development in flood-risk areas. Planning consents for homes in high-risk areas rose from 23 (2015–16) to 686 (2016–17) and 1,221 (2017–18); 652 in 2018–19, still far above the 2015–16 figure, and possibly undercounted.
Are the laws fit for purpose? Practitioners broadly feel current frameworks don’t fully support managing flood and erosion risk; the Committee prioritised three issues — responsibility for infrastructure, clarity of roles, and integration with climate adaptation.