Nature holds key to tackling flood risks

Flooding remains Ireland’s top climate vulnerability, and it once again came home to bite in county Cork in October 2023 when the town of Midleton and some surrounding areas were inundated, with millions of euros in damages, but thankfully, no loss of life this time. I filed the below comment piece for in the wake of this event.

NATURE, TO BE commanded, must first be obeyed. This is a lesson that the citizens of a once-notorious flooding blackspot in North Yorkshire took to heart, and it has paid off dramatic dividends.

Between 1999 and 2007, the town of Pickering was flooded four times, with the damage running in to many millions of pounds. The town was refused a £20 million flood defence scheme on the grounds of the cost being too high to protect a limited number of people.

In any event, the large concrete works being proposed would have been an eyesore in a town that depends on tourism income. Instead, they brought in academics and environmentalists as well as experts from the UK Environmental Agency and Forestry Commission to study the root cause of the repeated flooding: water rushing off the nearby hills and dales.

A series of nature-based solutions were developed, including hand-built leaky dams made of logs and branches, as well as planting woodlands and other measures, such as preventing uplands being burned, to slow down and trap rainfall.

The total cost was £2 million, or one tenth of the cost of the proposed concrete wall for the town centre and the project has been a roaring success. Pickering has remained dry as other towns in the region have been repeatedly inundated by increasingly severe rainfall, fuelled by climate change.

The success of this intervention has since been replicated in other communities in England and Scotland. A project to restore natural Culm grasslands in Devon has for instance seen the land’s ability to retain water increase five-fold.

The initial reaction to the flooding disaster in country Cork in recent days has been to focus on “hard” engineering solutions, including demands by some politicians to reform the planning system, ostensibly to prevent objections to flood relief schemes.

It is noteworthy that many of the local politicians blaming the planning system for failing to deal with the kind of flooding that has devastated their local areas can often be found to ignore the advice of their own engineers and vote in favour of rezoning land in flood plains for housing.

While there is undoubtedly a role for flood relief schemes in specific areas where high value infrastructure needs to be protected, the political and media clamour to “do something” after the latest flooding disaster sees nature-based solutions being ignored or even blamed as mega-engineering projects are instead rushed through.

As the examples of Pickering and elsewhere have clearly shown, the only truly sustainable long term solution to flooding is to tackle it at source. By the time tens of millions of litres of flood waters are rushing into your town or village, it’s usually too late.

Nature provides the answer

Climate minister Eamon Ryan at the weekend stated that a critical part of how Ireland responds to the worsening threat of extreme rainfall and flooding is to change how we manage our land, including paying farmers to develop new practices that will reduce the amount of excess rainfall sweeping off farmlands and uplands and swamping local towns and communities.

Some of the methods he proposed included planting different species of grasses with deeper root systems that are better able to absorb flooding, as well as developing native forestry and allowing some rewilding.

“It is going to be a case of paying and making sure we have the right incentives so that in the upper catchments particularly you slow the water down, and in that way, reduce the problem in our towns and villages and cities”, Ryan told the Green Party conference at the weekend.

Ireland’s peatlands form excellent natural sponges to absorb torrential downpours, especially in the flood-prone midlands. However, decades of industrial peat extraction have damaged and degraded much of this natural bulwark against flooding.

The government’s Climate Action Plan 2023 identifies peatland rehabilitation as offering increased natural capital, enriched biodiversity and improved water quality and flood attenuation.

The overall target is to rehabilitate 77,600 hectares of boglands by 2030. The absolute value of this work in terms of reducing the likelihood of devastating flooding events should become clearer over time.

For many decades, the Office of Public Works (OPW) has implemented arterial drainage schemes, which have included dredging and straightening rivers and tributaries and “protecting” farmlands in flood plains from being routinely inundated.

While this may at one time have seemed like a good idea, the simple fact is that water has to go somewhere. If we prevent rivers from spreading into their natural floodplains during times of flooding, and if land management practices are degrading the ability of our uplands to retain rainfall, the water is instead being pushed downstream, with entirely predictable consequences.

The drainage of bogs and wetlands and the “improvement” of lands, as well as allowing housing to be built on floodplains is picking a fight with nature, and it’s a fight that we will lose, every time.

Farmers whose lands are likely to be flooded as a result should of course be compensated via agri-environmental schemes, but it is infinitely cheaper to allow water to spread into its natural floodplains than have it canalised and then smash into our towns and cities, with devastating consequences.

This is not a drill

In 2023, the planet has warmed by around 1.5C versus pre-industrial. This temperature shift means the atmosphere is now capable of holding around 10% more water than a century ago. This is the largest shift in the global hydrological cycle since the end of the last Ice Age 12,000 years ago.

Warming oceans are providing the fuels for powerful storms and the warmer atmosphere is now delivering more intense deluges, both in Ireland and across Europe and much of the world, than have been witnessed in centuries.

According to climate scientists at the Irish Centre for High End Computing, more flooding is probably the biggest change Ireland will experience by the 2050s.

Basing your entire flood defence strategy around building concrete barriers assumes you know exactly how much flooding you are trying to defend against.

If for instance tens of millions of euros are invested in building, say a town’s defences to cope with 2-3 metres of peak flooding, the scope for a tragedy should this town be hit by a 4-metre event that breaches these defences and places the people behind them at real risk of drowning.

As global temperatures continue to rise, these scenarios are already playing out, in real time, right across the world. The smart move is to work with nature, not against it, but are our politicians and engineers open-minded enough to listen?

ThinkOrSwim is a blog by journalist John Gibbons focusing on the inter-related crises involving climate change, sustainability, resource depletion, energy and biodiversity loss
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