Despite increased expenditure and significant activity, there is limited evidence that flood risk management arrangements in the North are demonstrating long-term value for money in a systematic and comprehensive way.

That is among the findings of a report published by the Comptroller and Auditor General this week.

Dorinnia Carville’s report examines how the Department for Infrastructure and its partners are managing flood risk.

Flooding is one of the most significant natural hazards with approximately 45,000 properties across the North currently located within river and coastal flood plains.

Flooding in the Foyle Road area during torrential rain.

placeholder image — Flooding in the Foyle Road area during torrential rain.

Thousands more properties at risk from reservoirs and surface water flooding. Climate change is expected to increase both the frequency and severity of these risks in the coming decades.

DfI has reported increasing levels of investment in flood risk management activities, with total expenditure reaching £96 million in 2024-25 (a 73 per cent increase since 2020–21). Most of this investment relates to prevention and protection measures.

The report notes that Flood Risk Management Plans, which coordinate activity across a range of public bodies, have not sufficiently focussed on defined and measurable outcomes.

Ms. Carville says DfI’s oversight of applications for development of homes and other buildings in areas of known flood risk is limited and Flood Maps are not always updated in a timely manner following completion of new flood defence schemes.

Analysis of 21 completed flood alleviation schemes shows that only around one in five projects was completed on time, with delays in some cases extending by more than three years.

Similarly, only a small proportion of projects were delivered within close proximity of their estimated cost - final expenditure for some schemes varied widely from initial projections, from 48 per cent under to 118 per cent overspent.

Ms. Carville said: “Flooding already poses a significant and growing risk to people, property and infrastructure across Northern Ireland, and this risk is expected to increase further as the climate changes.

"While the Department and its partners have undertaken a significant programme of work, our report highlights areas where arrangements can be strengthened.

“In particular, there is a need for clearer outcome-focused planning, improved oversight of development in flood risk areas, and more robust delivery of flood defence schemes."