Water, water

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Rivers are over-topping their banks

It’s been a bit wet in the UK recently. When we compared our rainfall data for 2014 with that for this year, we saw that we’ve had approximately 50% more in November and more than 60% more in December (and it’s not quite over yet).

We are lucky in that we live on a hill and, although water flows through our garden from the field behind, it doesn’t hang around for long. In addition, our raised beds and raised chicken area act like sponges, and then drain gradually once the rain stops. Others are not so fortunate. Those living in the bottom of valleys are on the receiving end of all the water that has drained off the land further up the catchment. And so in recent days there is news of flooding in such locations.

It seems that we have suffered much more severe floods in recent years than previously and the media is keen to apportion blame… councils allowing developers to build on floodplains for example or upland livestock farming. But it’s a complicated picture and there are lots of reasons behind the current situation. Which means there isn’t a magic bullet – we can’t do one single thing to solve the problem.

Perhaps the first thing to consider is that this is about changing climate. By putting a blanket of carbon dioxide (and other greenhouse gasses) around our planet, we are trapping energy in our atmosphere. The result is the increase in storms and severe weather events. You will see many claims in the media that our changing climate is not the result of human activity. These often come from such renowned “experts” as Nigel Lawson, with his degree in Philosophy, Politics, and Economics and James Delingpole, with his degree in English Literature. If you are interested to see the credentials of those in the public eye who are sceptical about climate change, check out the DeSmog disinformation database. In contrast, the people actually undertaking scientific research about climate change overwhelmingly agree that it’s happening and that it’s anthropogenic. Indeed, according to NASA:

Multiple studies published in peer-reviewed scientific journals show that 97 percent or more of actively publishing climate scientists agree: Climate-warming trends over the past century are very likely due to human activities. In addition, most of the leading scientific organizations worldwide have issued public statements endorsing this position.

So, that’s something to bear in mind.

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The local supermarket car park will soon be awash

But, back to the floods themselves… There are several things that we need to do. We need to remember that floodplains serve a particular purpose in a river catchment, and that is not providing flat land for housing! Apart from anything else, floodplains are where rivers should be able to overflow; where the water spreads out, slows down and deposits the soil particles that it’s carrying before it reaches the sea. Floodplains should be the place where we catch the fertility of the land before allowing it to be washed away, and where, as a result, we can farm productively in the drier months. Channelling water so that it moves rapidly through this part of the catchment means that the energy is not dissipated and any nutrients will disappear out to sea.

Further up river catchments we also need to slow down the movement of water. We need to develop a landscape that holds water – upland bogs and grazed diverse grasslands are good for this – and where water is intercepted by trees and shrubs. We don’t need a smooth landscape where water just flows off – we need diverse topography, with pools, banks along contours, a mixture of vegetation types and a well-developed soil. Upland woodlands slow the movement of water, from the moment it falls. Leaves, twigs and branches intercept rain and increase the time it takes for that water to reach the surface. Tree roots make the ground more permeable, and this increases infiltration. Plus, the organic nature of deciduous woodland soils means they act like a sponge and hold large amounts of water.

Anywhere in the catchment, we can make a difference to the water-holding capacity of soil. You are doing this if you add compost to the beds in your garden. In addition, any organic matter incorporated into the soil (whether in a tiny garden or on a large farm) is acting as a sink for carbon and thus reducing net greenhouse gas emissions. These are really good reasons to compost waste and to treat any organic matter as a resource not a problem to be disposed of… not to mention increasing soil fertility and therefore allowing you to grow better crops, which photosynthesise and thus also reduce carbon dioxide in the atmosphere. Another benefit, is that increasing the water-holding capacity of soils reduces the impact of droughts – something we have also encountered recently. Adding organic matter, therefore, is a win-win situation.

So, whilst we can’t stop the flooding right now, we can manage our land better to reduce problems in the future. And we can all do this – plant a tree, make compost, build a garden bed, collect rainwater to flush the toilet or water your house plants. Every action helps and together we can make a difference.

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Over the banks but not over the bridge

 

 

Water, water everywhere

We live near a town called Aberystwyth… it’s hit national headlines because it’s been rather wet there. After two days of unusually heavy rain the River Rheidol burst its banks, as did many other streams and rivers in north Ceredigion (we live in the south of the county). The rain on Friday was astonishing, and in combination with a high tide on Saturday, many business and homes were flooded and roads closed. I have friends who have been flooded despite living three miles up in the mountains – the water just came over the land as well as along the stream which they are well above in their house. So when you hear people say ‘what do you expect if you live on a floodplain’ then please remember that not everyone affected lives at sea level or very close to a river.

We have lived in the area for 25 years and have never seen anything like this; but then, there are reports suggesting that there may have been 10 inches of rain in 24 hours up in the mountains on Friday! Of course some of the worst affected areas are those at sea level, where there is also a tidal influence. And it is remarkably short-sighted to continue to build on floodplains. First because the risk of flooding is greater there and, second, because these areas have flooded historically, they have wonderfully fertile soil. Surely we should be using this brilliant natural resource to grow things… even if crops get inundated sometimes, people and their homes won’t.

But it’s not just about where we build houses and businesses, the problem with flooding is that it’s really caused by what’s upstream in the river catchment and how quickly water moves through the landscape. If the land is wooded, lots of rain is intercepted on its way down to the ground, so it is slowed in its journey to the surface and may even have the opportunity to evaporate and return to the air. All vegetation intercepts rainfall, but trees with leaves probably do it best because they have a big surface area. Not only that, but trees create deep permeable soils, with their roots penetrating the ground and lots of organic matter from their fallen leaves acting like a sponge. The more wooded the upper catchments of our rivers, the slower the water moves through them and the more buffering there is from flooding. The opposite is equally true – make the ground less permeable and water moves through it quickly, all arriving at the rivers in a very short time and resulting in flooding. So, roads and storm drains and buildings and concrete yards and patios and field drains all contribute to flooding by speeding up the movement of water through the landscape. Grassland is not as good at intercepting water as woodland, and shallow rooted plants are likely to be associated with less permeable soil than deep-rooted ones.

Whilst the latest flood could not have been avoided no matter what the land use in Ceredigion, it could have been reduced if we had more woodlands (especially in the uplands) and a generally more permeable landscape throughout the river catchments. And many of us can do something about this… if you have a garden, you could make sure that the ground is permeable  – so no more patios and paved driveways, consider gravel and grasscrete. Build up the organic matter in your garden – this will help to hold water and be an effective defence against both flood and drought. Install water butts, so that you catch as much of that precious commodity as you can when it’s plentiful and prevent it literally going down the drain. And, finally plant trees and shrubs to intercept the water, root deep into the soil to allow water to percolate down and provide shelter from sun and wind which will dry out your garden anyway.

-oOo-

There are some astonishing photos of the floods  on Keith Morris’ facebook page and more photos and a fascinating explanation of the weather that caused the flooding here.

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