Dredging alone will not contain flood risk, but a new study in Ireland finds that natural flood management techniques such as the ‘Slowing the Flow’ project in England and the ‘Room for Rivers’ in the Netherlands, are being ignored.
The study says that in Ireland, dredging continues on many river channels despite its tendency to exacerbate downstream flooding. Agricultural land use changes have reduced the permeability of soils and increased paving has reduced permeability in urban areas. Drainage and infilling of wetlands has resulted in loss of natural flood water storage basins.
The new study (pdf) commissioned by Friends of the Earth, found that natural land management techniques can significantly reduce flood risk but are being ignored by Irish policy-makers, despite evidence of their contribution to flood management around Europe. Natural Flood Management is a comprehensive approach to managing soil, wetlands, woodlands and floodplains along a river to retain and slow water at times of flood risk, reducing the speed and the peak of floodwaters compared to approaches that rely only on dredging and walls. The report, commissioned by Friends of the Earth, was launched at an event to mark World Wetlands Day in Dublin City Council.
Speaking at the launch, the report’s author, ecologist and broadcaster, Anja Murray said:
“Natural flood management has gained recognition in many countries as a viable and cost effective approach to flood risk management, with extensive projects across Europe and further afield that have restored peat bogs, planted riparian woodlands, restored and created new wetlands, re-profiled rivers and their floodplains to hold back floodwaters.
“Natural flood management is virtually unknown in Ireland, despite the growing problem of widespread flood damage in recent years and forecasts of worse to come. There have been no trials or pilots of catchment based approaches to flood management in Ireland, despite the evidence that natural flood management can be an effective means of significantly reducing flood peak.”
Welcoming the study’s findings, Friends of the Earth Director, Oisin Coghlan said:
“Our climate is warming. Major flood events, currently expected once in every 50 years, are likely to occur once every 10 years by the second half of this century. We commissioned this study because we want Ireland to protect our communities as effectively as possible from the impacts of climate change. This study shows that building our flood resilience is about more than building walls and dredging rivers.
“It’s hard to fathom why natural flood management techniques have been ignored in Ireland, despite the evidence of their contribution elsewhere. There has been a rush to expensive engineering responses in the face in understandable public anger. We hope this report will start a conversation about how to make our flood risk management more evidence-based, less narrowly focused, and ultimately more effective.”
The report, “Natural Flood Management: Adopting ecosystem approaches to managing flood risk”, (pdf) analyses a whole-catchment approach to managing flood waters, through managing soil, wetlands, woodlands and floodplains to retain water strategically at times of flood risk. In recent decades urban and agricultural expansion and intensification, often onto historic floodplains, has resulted in the loss of capacity of floodplains to lessen the impact of flooding. Dredging continues on many river channels despite its tendency to exacerbate downstream flooding. Agricultural land use changes have reduced the permeability of soils and increased paving has reduced permeability in urban areas. Drainage and infilling of wetlands has resulted in loss of natural flood water storage basins.
Now, in response to increasing frequency of extreme rainfall events and consequent flooding that is happening because of climate change, Ireland needs to urgently develop and implement measures to reverse the decline in natural flood attenuation. Exclusive reliance on hard engineered flood protection works no longer represents the optimal approach to managing flood risk. Instead, combinations of catchment wide measures are now evidenced as good international practice. Measures include peat bog restoration, woodland creation, incentivised agricultural land use changes, floodplain restoration, wetland protection, and managed coastal realignment.
Case studies are presented of projects which have successfully implemented natural flood management, including ‘Slowing the Flow’ project in North Yorkshire and the ‘Room for Rivers’ in the Netherlands. The report finds that strong community involvement in addressing flood risk is crucial, as is the involvement of a range of interests and state agencies in recognition of the wider environmental co-benefits of natural flood management.
The study was commissioned by Friends of the Earth with a grant from the Irish Environmental Network.