When soil is depleted of organic matter, water just runs off it. A rethink of farming practice is much more vital than dredging or barriers.
The Prince of Wales’s visit to the Somerset Levels has once more drawn attention to the dire circumstances faced by thousands of people because of floods. And as more extreme rain drenches the UK, calls for more flood defences and river dredging have predictably become louder. There is, however, another focus that has been hardly mentioned. It’s soil or, more specifically, the benefits we could gain by treating it better.
The way we use land has fundamentally altered the way that many of our soils work. Intensive cultivation and grazing cause massive soil loss, with sediments leaving fields to clog up watercourses. Machinery and animal hooves have also caused many soils to become compacted so that, instead of absorbing water, holding it and slowly letting it go, it runs off hard impermeable surfaces all at once.
Because of intensive farming reliant on inorganic fertilizers, there has also been a widespread reduction in the proportion of soils comprising decaying plant remains – the so-called organic matter. Soils depleted in this way hold less water than when they have a healthier proportion of once living material, thereby further altering their ability to ameliorate flood risk.
In upland areas, the degradation of peat soils by burning, drainage and the cutting of peat for fuel means that the many areas of blanket bog that clothe Britain’s hills and mountains can no longer serve their function as giant sponges that catch and hold rain. Instead, water runs off the land, exacerbating flood risk downstream.
In many of our river valleys, the floodplains that would once have spread water coming from the hills over wetland soils (in the process recharging ground water) are now covered with houses. Instead of spilling across grasslands, the water now lies in people’s sitting rooms.
A lot of the problem, of course, arises from the cock-eyed approach we take toward economics, and on how we tend to base policies on the short-term upsides of the choices we make, rather than taking an integrated view that includes all the costs.
The drive for inexpensive food is a case in point. Such food only appears cheap, however, because it excludes the many costs that come with the soil damage it causes. The drive to build houses at volume to the point where the advice of the Environment Agency as to the risks of building in flood plains is ignored, similarly counts only the benefits of development now, not the risks it exposes to society later on. This need not remain the direction of travel, however.
More intelligent use of farm subsidies is one obvious lever we can use, and if done right could bring many benefits to society that go beyond flood risk reduction. For example, healthier soils can help to mitigate the effects of drought on crops (another kind of extreme we can expect more of as the climate changes), they hold more carbon (and thus help keep carbon dioxide out of the air) and can improve water quality and thereby keep downward pressure on water bills.
Soil is, of course, also the main natural system we need for food, so keeping it healthy and on fields, rather than degraded and on its way to the sea down rivers, has to be good for the long-term security of the country. Restoring upland and lowland wetlands so that the soils on floodplains and blanket bogs works better would not only help to manage flood risk but also help conserve wildlife.
The use of farm payments and other incentives to restore woodlands, hedgerows, grasslands and to renaturalise rivers would assist as well.
So let’s end the simplistic nonsense that leads us to focus only on concrete defences and destructive dredging, and instead take what is ultimately a more rational and integrated approach. If we did that we’d get far more for our money.
Prince Charles Visits Flood Sights