We all know what’s gone wrong, or we think we do: not enough spending on flood defenses. It’s true that government cuts in countries such as the UK have exposed thousands of homes to greater risk, and that the cuts will become more dangerous as climate change kicks in. However, too little public spending is a small part of the problem. It is dwarfed by another factor, which has been overlooked in discussions in the media and statements by the government: too much public spending.
Vast amounts of public money, running into billions, are spent every year on policies that make devastating floods inevitable. This is the story that has not been told, a story of outrageous destructive perversity.
Flood defense, or so we are told almost everywhere, is about how much concrete you can pour. It’s about not building houses in stupid places on the floodplain, and about using clever new engineering techniques to defend those already there, but that’s a small part of the story. To listen to recent dismal debates, you could be forgiven for believing that rivers arise in the plains; that there is no such thing as upstream; that mountains, hills, catchments and watersheds are irrelevant to the question of whether or not homes and infrastructure get drowned.
The story begins with a group of visionary farmers at Pontbren, in the headwaters of Britain’s longest river, the Severn. In the 1990s they realized that the usual hill-farming strategy — loading the land with more and bigger sheep, grubbing up the trees and hedges, digging more drains — was not working. It made no economic sense, the animals had nowhere to shelter, and the farmers were breaking their backs to wreck their own land.
So they devised something beautiful. They began planting shelter belts of trees along the contours. They stopped draining the wettest ground and built ponds to catch the water instead. They cut and chipped some of the wood they grew to make bedding for their animals, which meant that they no longer spent a fortune buying straw. Then they used the composted bedding, in a perfect closed loop, to cultivate more trees.
One day a government consultant was walking over their fields during a rainstorm. He noticed something that fascinated him. The water flashing off the land suddenly disappeared when it reached the belts of trees the farmers had planted. This prompted a major research program, which produced the following astonishing results: Water sinks into the soil under trees at 67 times the rate at which it sinks into the soil under grass. The roots of the trees provide channels down which the water flows, deep into the ground. The soil there becomes a sponge, a reservoir which sucks up water and then releases it slowly. In the pastures, by contrast, the small sharp hooves of the sheep puddle the ground, making it almost impermeable, a hard pan off which the rain gushes.
One of the research papers estimates that — even though only 5 percent of the Pontbren land has been reforested — if all the farmers in the catchment did the same thing, flooding peaks downstream would be reduced by about 29 percent. Full reforestation would reduce the peaks by about 50 percent. For the residents of Shrewsbury, Gloucester and the other towns ravaged by endless Severn floods, that means — more or less — problem solved.