Flooding — an ongoing manmade disaster?

In June 2007 Sheffield was engulfed by a flood after torrential rain fell on the hills above the city. Two people died, there was enormous damage and the city spent over £50 million in strengthening flood defences.

This was not a unique event. Flooding happens in many places across the United Kingdom. For example, the Calder Valley has flooded several times in recent years, in 2014 much of Somerset was under water for weeks after Atlantic storms and high tides coincided, and the city of York seems to be perpetually under threat during winter months.

What is common across all these events? One is the kneejerk response in each case: to build better flood defences and to improve drainage through dredging or river widening. But another is a regular failure to talk about systemic factors contributing to these disasters.

Historically, Britain would have been heavily covered by trees, and trees form a very important first line of flood prevention by slowing water flow and absorbing water through their roots. However, population growth and intensive agricultural activity have removed much of this tree cover, so fallen rain now flows much more quickly across the land and into rivers. In many areas this has been compounded by centuries of animal grazing: as sheep and cattle walk ceaselessly around fields they compact the soil making it less permeable to falling rain.

As rainwater flows over the surface of fields it carries topsoil away into streams and rivers. Then, as the rivers meander slowly across lowland plains towards urban areas this slowly settles as silt, reducing the ability of the rivers to drain the water. This makes flooding more likely, and as this has an impact on agricultural productivity farmers will often build embankments or dredge rivers to increase flow. But the water has to go somewhere, and often ends up constricted by culverts and bridges as it flows through towns and cities, so the problem of flooding is simply transferred to urban areas. The private benefit to farmers leads to increased public cost in towns and cities.

Pennine towns and cities such as Sheffield and Hebden Bridge are also affected by the clearance of forest on high ground to create open moorland for hunting and shooting. Grouse shooting in particular demands that large areas of heather each year are burnt off, but research shows that burning peat soils such as in the Pennines causes much faster water run-off when there is heavy rain. Irrespective of the moral issues surrounding shooting wild birds, the pleasure for those rich enough to go shooting has a social cost to those of us living in the towns and cities below. Grouse shooting and deer stalking are often claimed to be an important part of rural economies, but they have a negative effect on society elsewhere. (For an interesting read on this subject, try local author Bob Berzin’s novel Snared (https://bob-berzins.co.uk/)). Private gain but public cost.

Flooding in Sheffield is also exacerbated because its many hillsides are heavily covered with tarmac. Our society’s dependence on cars leads to vast areas being covered by impermeable tarmac and concrete roads. This is compounded by people concreting over front gardens to create parking spaces. We only have to walk down a typically sloping Sheffield street in heavy rain to see the amount of water that rushes down beside the pavement to see this happening. While it is possible to turn a permeable garden into a permeable parking space using appropriate materials and designs, people often look for a quick fix: again, private gain but public cost.

As climate change intensifies we can expect more extreme weather events, which will include more rainfall and more powerful and wetter storms. Already, we have seen that in 2019 the new flood defences at Meadowhall were overwhelmed.

Sticking plaster solutions such as flood management schemes and dredging lowland rivers are not a solution. Rather, we should look to making upstream land better able to absorb rainwater as it falls. This means reforesting moorland areas and shrinking the areas dedicated to hunting and shooting. This will not be easy: the rich and powerful who enjoy these pursuits actively work to prevent changes to the landscape.

There needs to be more joined up thinking about how river catchments work. Currently, responsibility for managing different parts of rivers is divided up between different bodies and agencies, each of which have their own particular sectoral interests. For example, rivers should be allowed to meander across a landscape and flood surrounding agricultural land if necessary, but this will only be possible if farmers accept this as a solution and can be compensated appropriately.

Town-dwellers can make a contribution: replace impermeable drives outside our houses with permeable surfaces or make sure that run-off soaks into soil near our house rather than pours downhill; direct rain from rooves into water butts or install green rooves (which can improve house insulation). This may be a private cost but it will be a public gain.

Prevention is always better than a cure, and this is certainly true for flood management.

(This article was originally published in the Sheffield Telegraph in January 2023)