How will changing agricultural policy help reduce flooding?
Published on: 14 July 2014
Recent extreme weather has highlighted the problems we face when the rain causes flooding and washes away soil from intensively-farmed land. But can helping farmers to change the way they manage their land also help to solve problems of flooding and soil erosion?
Exeter’s Professor Richard Brazier works on soil erosion and understanding the effects of landscape restoration on water resources. He feels that improving farmers’ land management could have a big impact saying: “During wet winters, as we have recently experienced, you only need to look around the landscape to see that there’s evidence of local flooding and soil erosion everywhere.”
The devastation seen on the Somerset Levels has raised the awareness of the results of poor land management but Richard believes that changing the policy surrounding farm management could tackle these problems as well having long lasting financial and environmental benefits.
Richard’s NERC/TSB/South West Water funded Mires-on-the-Moor research showed how enhancing the water storage on Exmoor’s peat land can improve water quality and carbon storage as well as releasing less water into the River Exe during times of flooding.
With a third less water leaving experimental sites on the moorland during wet periods of the year, the results are certainly compelling and recent discussions with both local MP Ben Bradshaw and the Minister for Govt. Policy, Oliver Letwin, saw the research go all the way to the Houses of Parliament as evidence for change to land management policies.
Farmers are under intense pressure to farm commercially popular crops and livestock which means that the financial benefits they could see by changing their practice are an important matter.
Most scientists are in agreement that to mitigate flooding involves changing land use but there are difficulties involved, as Richard explained: “How can you persuade farmers to change their practice? Politically it’s very difficult.
“My suggestion is to create a political appetite for this by demonstrating that if you look holistically at a problem like flooding, you could find a solution that makes it more profitable to farm the land and deliver a number of environmental benefits alongside producing high quality food.”
Exmoor farmers are now encouraged to understand the financial benefit of this water storage by restoring their land and selling the water storage potential of the land back to the water company. In turn, the water company will have access to water which requires much less treatment and in the long term this could lead to reduced water bills.
Such landscape restoration can also achieve wider environmental benefits – with less CO2 and methane being released into the atmosphere from restored farmland and more carbon being stored in the soil there is a potential income stream for farmers to sell their restored land for its carbon storage properties.
Finally, landscape restoration such as ditch-blocking has been shown to reduce the amount of soil erosion that occurs, ensuring that less sediment is washed into rivers, which in turn may mean that dredging is required less often, if at all in the long-term.
At some point down the line soil erosion on farmland will result in there not being enough topsoil to farm, no matter how much fertiliser is added.
Professor Richard Brazier, Geography.
The moorland research project looked at how effective blocking drainage ditches would allow farmland on Exmoor to collect and store the water that would otherwise very rapidly run off the land.
Historically, much of the landscape of the south west UK, including the Somerset levels and moors, was covered with unimproved grassland and woodland that could store a lot of water.
The headwaters of these landscapes are now dominated by intensively farmed land, compacted and bare soils which generate floods quickly, eroding the soil.
Richard says his work on restoring the function of landscapes adopts a holistic approach: “It has a benefit for the water company – cleaner water and more water storage; it has a benefit for society – because it alleviates flooding downstream, and reduces the need for dredging – and it has a financial benefit for the farmer – as soil is retained on the fields and the farmer is rewarded financially for looking after their soil and water.”
The discussions with Ben Bradshaw looked at how the effects of extreme rainfall and drought on soil erosion and landscape can be managed through the construction of more resilient landscapes, which are better adapted to extreme weather.
The research has shown the capacity for water storage that different land types have. Working closely with The Devon Wildlife Trust and the Environment Agency, Richard’s research group have learned that the unimproved Culm Grasslands can store five times as much water as their intensively managed counterparts.
Dredging the silt from rivers every year is not a sustainable option, either economically, as it is costly, or environmentally, as it impacts on the ecological status of the rivers.
Richard explained that unless we tackle the underlying causes of flooding from farmland there could be disastrous results for agriculture. He said: “A lot of agricultural soil in the UK is very shallow. At some point down the line soil erosion on farmland will result in there not being enough topsoil to farm, no matter how much fertiliser is added.”
When the sun comes out we may forget about the damage the storms caused over the winter of 2013/2014, but a change in land management is no less important and would continue to deliver both environmental and economic benefits.
A landscape which stores water in the wet season and releases it more slowly in dry periods is more resilient to climatic variability and can help society to adapt to the kind of extreme weather that we have seen in recent months.