This post is by Daniel Johns, head of adaptation at the Committee on Climate Change.
Over centuries our communities have developed around rivers, to ensure easy access to water for use by populations, industry and for navigation. At the same time, landowners have straightened and dredged rivers, drained their land and removed natural features, aiming to raise agricultural output and get excess water away downstream as quickly as possible. But, in recent years, we have seen time and again the enormous cost of too much water at once flowing into our heavily populated floodplains, despite the billions spent by the government on flood defences.
Only last winter, storms Desmond, Eva and Frank caused damage estimated at £5 billion. Recently constructed flood defences were overwhelmed, such as those in Carlisle, as record rainfall came rushing off the hills. Herein lies part of the problem, but also part of the solution. The way we currently manage the land creates greater flood risk for communities. As the climate continues to warm, and the effects in terms of rainfall become ever clearer, it won’t be acceptable nor affordable in many cases to build higher and higher defences. Alongside continuing to invest in improved structures where we can, we need to harness the land to better deal with the flood water: to slow down and manage flood flows so that the defences can do the job they were built for.
Floodplains can’t do their job any more
Much of the most productive agricultural land in England is in the functional floodplain, with rich soils awash with nutrients from a history of flooding. But two fifths of the floodplain can no longer perform its natural function, as rivers are channelled within walls and embankments. It is ironic that we currently encourage farming on floodplains, through agricultural subsidies, and then we compensate farmers when this land floods. In the wider catchment, factors like heavy machinery, overgrazing, intensive burning and land modifications in the uplands, are drying, compacting and destroying soil structures. This means land is less able to absorb heavy rainfall. Fast flowing water down hillsides is washes fertile soils away into rivers, increasing costs and the demand for dredging.
So it is about time that the concept of natural flood management had a resurgence. Not as an alternative to engineered structures and downstream defences, but as a compliment to them. Natural flood management is not just about planting a few trees. It’s about taking a strategic look at the catchment and working out where and how to hold back and store flood water where it can cause least harm. We know from recent events that flooding causes little damage to agricultural land: a few hundred pounds per hectare, for example, in the winter of 2013-14. In contrast floods in urban areas causes millions of pounds worth of damage per hectare; tens of thousands per household in insurance costs and clean-up bills; lasting mental and physical well-being impacts on whole communities; and businesses struggling to recover.
Using the land more intelligently will limit flood damage
Whilst persistent flooding, especially involving damaging sea water, can affect yields, suitable crops can survive routine floods. In the widespread flood event in 2007, which occurred in the months before harvest, farmland accounted for less than two per cent of the £3 billion in damages. Whereas homes and businesses accounted for two-thirds: over £2 billion. So the more we can do to prevent urban flooding by using the land more intelligently the less overall damage there will be.
Some people might be concerned about the loss of productive land and about food security. But flooding of farmland is immaterial to whether there is plentiful, affordable and nutritious food available on the supermarket shelves, sourced as it is from around the UK and further afield.
Worthy of taxpayer support
Natural flood management offers farmers opportunities as well as compromises. Land can be used for more than one function, remaining productive but also serve the wider public interest. As we contemplate life outside the European Union there is an opportunity to fundamentally recast the system of agricultural subsidies. There is an economic rationale for paying farmers to use land to deliver public benefits. Returning floodplains to functional use, allowing rivers to slow and meander, and peatlands and soils to recover, are all public goods worthy of taxpayer support.
So Green Alliance’s new report Smarter flood risk management in England places an important challenge at the door of policy makers, the farming industry and upland landowners. We need to use land to sustain the economy, but also to protect communities, and to do this we can and should use it more wisely. We need to develop policies and approaches that value natural features, like healthy soils, wooded slopes and valleys, and functional floodplains, for the range of benefits they offer. Failing to do so will come at a high price that will be increasingly hard to afford.