Looking at vast areas of the country flooded yet again made me think about what we can do. Some of the answers are in the land.
Whatever we do, these extreme weather events are going to carry on. The ‘once in a hundred years’ rainfall that seems to come every few years now. We really need to do a lot more to protect ourselves and handle these events.
There’s no one solution, but rather a number of things we can do. Civil engineering works have their place but they’re expensive. Putting flood walls by rivers will give towns some protection but the cost is, rightly in my opinion, balanced against the benefits. How many houses will a scheme protect for the cost, being the question. This at least gets the best value for the money we as a society spend.
Green Engineering – Soil
Green engineering can offer even greater benefits but it takes time and isn’t always obvious. The first line of defence is the soil. It’s proven fact that humus-rich soil absorbs water. Clay, with its very fine particles and small pore spaces often repels water. Little can penetrate the surface and percolate down. Sandy soils with large particle size and pore spaces let water in easily but it washes through very quickly.
So the water gets quickly to the river which floods. By adding the magical humus and organic matter, clay particles aggregate into larger particles and both soils absorb and hold water like a sponge, releasing it at a rate the rivers can cope with. The deeper the top soil, the more it can hold.
Conventional farming has treated the soil badly. It’s been thought of as some sort of material to hold fertilisers for crops. Compacted by heavy machinery, those pores are closed and effectively it becomes a clay like soil.
There are farming methods that actually improve the soil, regenerative farming. Farmers are very conservative – they take a lot of persuading to jump on bandwagons and change. They think in long timescales, decades rather than months.
The government should fund research into these methods – proving them and finding the best practice. The cost of that would probably be a tenth of a modest flood defence scheme. Then give the farmers that information – they’re not fools, if they see a real benefit they’ll adopt the practices.
Don’t forget, properly managed grass land on deep top soil will absorb huge quantities of carbon as well, reducing CO2 in the atmosphere. Striking at the cause of climate change as well as coping with its results.
Green Engineering – Trees
Next we have trees. I’m not talking about replanting forests but bands of trees, planted where they’ll do the most good. They too absorb carbon and hold it but they also bind and stabilise soils. Creating more humus from their shed leaves and shielding from storm winds. When rain soaks the land, the trees drink it in as well. This helps to reduce the problem further.
Green Engineering – Swales
There are landscaping solutions than can help – although civil engineering and green engineering are blurring together here.
Swales are a water control system used in permaculture – often to make use of scare water in dry climates. Basically wide ditches that follow the contours of the land so they fill with water in rainy weather. Unlike ditches that usually drain into a stream, swales are level and the water slowly filters out into the soil on the the downhill side.
Often swales are edged with trees on the downhill side, with the same benefits from the trees as referred to above. They can also be built on a small scale. On a small scale they can be combined with French drains and ditches to provide localised protection.
Slowing Not Stopping Water
Improved topsoil, tree bands and swales will not stop water running off in an extreme rainstorm but they will slow down the run off. If, as happens, a month’s rain falls in a day the rivers swell with 30 days influx. If that run-off can be spread over 5 days, the problem is only a sixth as bad. Even if it only spreads the problem over two days, halving the problem can possibly avoid the catastrophic floods.
Further actions to help with floods.
Another green / civil engineering solution is to create storage ponds. Farmers often face two problems – lack of water and too much water. Building storage ponds on the land helps solve both problems. Of course they take some growing land out of production but drought and flood can take the whole crop – effectively all the land.
These ponds can be decorative, natural ecologies in themselves. Enhancing the landscape and eco-system whilst providing emergency water storage and supply for the farm land in drought.
All the answers?
I don’t pretend to have all the answers but it’s obvious we have to put more thought and energy into the problems coming with climate change and extreme weather. These green solutions are not free but they are cheaper than many of the hard engineering solutions being made.
Money – Loads of Money
According to the UK government
Flooding, and managing it, cost the UK around £2.2 billion each year: we currently spend around £800 million per annum on flood and coastal defences; and, even with the present flood defences, we experience an average of £1,400 million of damage. While the level of spending is fairly steady, damage due to flooding is intermittent and can be huge when a major flood occurs.
Full report Foresight Future Flooding
Spending more now – and remember we’re talking hundreds of millions – will save for more in the future, help with climate change and improve the environment for us all.