Cork city, in the south of Ireland, has a long history of flooding, including a number of significant events in recent years. Arup is working with the Office of Public Works (OPW), Cork City and County Councils, ESB and other members of the design team to enhance the city’s resilience against the effects of tidal and fluvial flooding.

The Lower Lee (Cork City) Flood Relief Scheme will protect 900 homes and 1,200 businesses from flooding and, when delivered, will be the largest flood relief scheme in Ireland. The scheme is being designed as the first key step in a long-term climate change strategy for Cork which is cognisant of the latest scientific evidence, including findings from the UN’s Intergovernmental Panel on Climate Change (IPCC).

Through regular stakeholder engagement and collaboration, the design team is incorporating feedback from residents, local businesses and government bodies to ensure the scheme provides wider multifaceted city benefits. The proposed flood protection measures will seamlessly integrate into the public realm, with new or enhanced walkways, cycleways and plazas providing new riverfront spaces for residents and visitors to enjoy.

Combining long-term protection with liveability

Arup's multidisciplinary team – including engineers, scientists, architects and planning advisors – are designing a scheme that combines flood protection measures to protect Cork today with an ability to adapt to the future challenges posed by climate change.

The proposed scheme incorporates biodiversity enhancements in rural areas and public parks, while urban plazas and riverside walkways will cast the River Lee as a central character woven into the daily lives of locals and visitors.

Innovative flood defence elements such as built-in benches along the riverfront will offer a space for leisure and double up as defences in combination with demountable, tilt-up barriers during floods.

CGI of Cork’s Lower Lee Flood Relief Scheme. Credit: Office of Public Works (OPW)
Improvements to public spaces are central to the proposed scheme. Image © Office of Public Works (OPW)
CGI of Cork’s Lower Lee Flood Relief Scheme. Credit: Office of Public Works (OPW)
Demountable barriers will be used only during times of flood. Image © Office of Public Works (OPW)
CGI of Cork’s Lower Lee Flood Relief Scheme. Credit: Office of Public Works (OPW)
The proposed scheme will incorporate significant biodiversity enhancements in rural areas and public parks. Image © Office of Public Works (OPW)

Optimising dam operation to better manage flood risk

In collaboration with the Electricity Supply Board (ESB), we developed an integrated catchment approach which will involve further optimising the existing hydroelectric dam operation to improve flood risk management.

The risk of peak flows from the dams reaching the city will be reduced by almost 40%, enabling the required quayside defences to be minimised. These low-level defences are being designed to perform their flood defence function well into the future. Existing floodplains will be used as washlands to maximise the capacity of the reservoirs.

A flow control structure at the head of the southern channel will be used to rebalance flows between the north and the south channels, reducing the risk of flooding and minimising the requirement for defences.

CGI of Cork’s Lower Lee Flood Relief Scheme.
The Lower Lee Flood Relief Scheme will create a more future-ready Cork, helping the city to adapt to the challenges posed by climate change.

Using digital tools to optimise flood defences

Arup and JBA Consulting built an integrated continuous simulation model to predict rainfall patterns and river flows over a theoretical 1,000-year period in order to calculate the design flows of the river.

By modelling the city’s groundwater regime, Arup ensured that all possible flow paths were considered and suitable protection measures incorporated. The scheme is being designed to provide protection against 1-in-100-year fluvial and 1-in-200-year tidal flood events.

Maximising the benefits for local residents and businesses is being prioritised throughout the design. Beyond protecting against flood risks, the proposed scheme involves upgrading and regenerating riverfront areas of the city, providing new urban spaces for people to enjoy.

CGI of Cork’s Lower Lee Flood Relief Scheme. Credit: Office of Public Works (OPW)
The scheme will protect 900 homes and 1,200 businesses from flooding.