Institution of Civil Engineers | Spotlight
A holistic approach to flood risk
Over the past two decades or so, we have witnessed more extreme storm events, involving unprecedented rainfall.
Resulting floods have severely damaged properties, caused energy and transport disruption, contributed to mental health issues and sadly resulted in loss of life.
ROGER FALCONER
In the UK, we have also seen combined stormwater overflows and diffuse source pollution from agriculture contributing to the deterioration of water quality and the ecological status of many rivers.
We are dealing with a series of interconnected and complicated challenges across the water sector, not just in the UK, but worldwide.
In the UK we are not set up with the best framework to deal with these challenges. We have a complex water basin system involving many stakeholders with conflicting objectives.
Key organisations include regulatory agencies for surface river flooding, water companies for sewer flooding, highway authorities for road flooding, local and regional authorities, internal drainage boards, landowners etcetera.
These organisations often have different regional boundaries. In turn, these regional boundaries rarely match river basin boundaries, which run from the top of catchments to the coast.
Additionally, the criteria used to determine and design for flood risk also differs across these various organisations. For example, the regulatory authority typically designs to a 1 in 100-year risk, whereas the water company typically designs to a 1 in 30 year risk.
Compare this system to countries in the AsiaPacific region, where convective and tropical storms are frequent.
In many of these countries a single organisation, like the Department of Irrigation and Drainage in Malaysia, is responsible for flood risk management.
Unsurprisingly there are often shortcomings in effectively managing water quality and flood risks in river basins in the UK. There are simply too many organisations involved in managing river and subsurface systems.
We need to approach flood and water quality risks in a more holistic way. Fortunately, there are best practice examples to learn from.
“In the UK we are not set up with the best framework to deal with these challengesIn November 2019, South Yorkshire had a month’s worth of rainfall in 24 hours. Over 1,000 homes were evacuated and key infrastructure impacted. This devastating event was the catalyst for the creation of Connected by Water, an alliance between combined authorities, local councils, Yorkshire Water, and the Environment Agency.
These organisations work in partnership and with local communities and businesses to build flood resilience and reduce the impact of future extreme weather events.
Connected by Water takes a river basin approach to managing flood and water quality risk. Since its establishment, it has created an action plan and is developing ambitious new programmes. It has developed flood alleviation schemes and built capacity to respond to floods across South Yorkshire.
We know climate change is happening and more extreme weather events will happen in the future.
Many regions and governments could learn from South Yorkshire’s example.
- Roger Falconer is an ICE Yorkshire and Humber regional committee member and independent water consultant