Saturday, 13 October 2012

Water Water Everywhere

You may have seen the news about the flash flooding in Clovelly, North Devon. Much of the footage was taken by myself and other Clovelly residents. A few houses and businesses suffered badly, but nobody was hurt. So what happened? In this article I'll explain a little about how floods happen, how to get through them as well as some preparations and survival tips taught in Emergency Preparedness courses.

First, let's look at the evidence. This is a short video, some of which was used by the BBC showing the  volume of water that came down the street without any warning, other than the fact it had rained for quite a while, which is not unusual round these parts.
The video starts at my front door, past the museum and over to the main street where the brunt of the water was flowing down the street at a great rate. 

As you can see, many of the doors to the houses are raised from street level, which is why so many managed to get away without being filled up with water, which is what we'd expect to see in such circumstances.

You would be forgiven for thinking that this would be the normal scene of a river, heavy with rain water along side which people had built houses. In fact, there is a great deal of truth in this. Historically, those Clovelly was build alongside the river that flowed down to the sea, where a productive fishing harbour supported much of the village. The street was raised from a pair of an made gulleys which transported the water and each house had a bridge over it to their door or front garden. This system managed all manner of rain water and the village did not flood. So what changed?

This is a current map showing the river which formally ran through centre of the village. As you can see, it has been diverted from its normal course around the village to the sea. This was done towards the end of the 19th century, championed by Charles Kingsley, who identified the river as a source of Cholera, which in those days was not well understood and caused many deaths.

The project was a great success and river had generally maintained this new course, leaving the village not only free of disease, but of flood water, which the new course could handle adequately. So if the system had worked for over 100 years, what changed?

A number of contributing factors, on top of the rain, caused the flood, but let's first look at how floods occur. Very simply, water falls from the sky, some of it seeps into the land and some flows away, down hill. These efficient water courses start as brooks and develop into wider rivers as smaller waterways join together on their route to the sea. Clearly, the further you are down hill, the more water is coming your way. Like pipes in plumbing, there is a maximum capacity which the river can hold and channel away. The soggy earth acts as a buffer, slowing the initial progress and retaining some water which dissipates gradually after the rain has passed. If the volume of water falling and flowing exceeds this maximum rate of flow of the river, then the banks overflow, or burst, and the water begins to flow over the now saturated land down hill. This would normally be along the same course as the river, but not in the case of Clovelly. Here, the water retook the most direct route down hill, that of the original river through the middle of the village.

So couldn't the drains cope? The original, large capacity gulley system had been filled in and replaced with an underground drainage system that was designed to cope not with the original river volume, but that of heavy rainfall over a much smaller area below and to the side of the new river course, which was to take the water from higher ground. In addition, when the river broke its bank, it flowed over gardens, cutting a swathe through lawns and flower beds bringing with it sods of earth, grass and even bulbs as well as small stones and silt which immediately blocked the drains, rendering them useless. By the time we unblocked the drains, much of the debris had already come though, so they began to reduce the flow over the street without reblocking.

Another factor which affects the amount of water entering the rivers is that of modern drainage in fields. Clearly, by effectively draining rain water from fields, the buffering is lost and the water immediately enters the system, dramatically increasing the amount of water flowing. In addition, redirected rivers suffer from deposits forming at the point of change of direction which reduces the capacity at that point, making is prone to heavy flow.

So some combination of these factors meant that a great deal of water arrived on a street not capable of dealing with it and as the water flowed over the breach point, it cut a new, more direct path ensuring that most of the water would continue to take that route, even after the rain had stopped and the flow reduced.

So what did we do? A number of self organising groups threw on wellies and headed out into the street to see what needed to be done. Initially, concerns were for those whose houses had water flowing through them. It was noted on entering one house that the cooker clock was still on, and as we were standing shin deep in water, the shutting down of the electrics was considered the first priority. With an electrician on hand, this was quickly located and the supply suitably isolated. From our survival priorities, this is our first; concern with further danger, in this case, electrocution. Other concerns might have been structural, but in this case, the houses were as solid as any house that's stood for hundred of years. These dangers have to be addressed before any further action is taken, since there's no point in rescuing the rabbit, if you're going to both get zapped in the process.

Wellington boots were pretty much the uniform. I went for gore-tex socks to keep my feet dry when the water came over the top and thermal socks underneath to keep warm. Others had waders. There was a mix of trousers, shorts, swimming shorts, waterproofs, no waterproofs and a variety of hats. As it wasn't a particularly cold day, it didn't really matter about being soaking wet, but had it been colder, hypothermia could have been a concern, which is no good at all. Always choose appropriate clothing from the onset, because once you're in the thick of it, there's not telling when you'll get a break to get back and change and as you know, once you're cold and wet, it's quite hard to catch up to normal.

With all pets accounted for and that which was savable or looking like it might be taken be the rising water popped on the stairs, thoughts turned to stemming the flow of water into the buildings. In some cases this was impossible as cascades of water were flowing from back door to front. In other cases, judicious placement of planks and coal bags redirected a sufficient amount of water that level dropped below the door step and the house stopped filling.

There's a knack to moving through flowing flood water and it's related to river crossing. With water having a mass of 1 tonne per cubic metre, you cam imagine that the volume alone can be enough to knock you over. In this case, ropes were not deemed necessary, but we did ensure we walked using the railings. When crossing was required, my favoured tool was a broom, which I used inverted as support under the water. In addition, with the water being opaque, this prodder allowed me to locate not only steps and dips, but also open drain covers, which though unusual in Clovelly, is more common when the sewers are flooding.

When sewers flood, there are additional concerns. First, the open man hole covers, which have obvious danger. Second the man hole covers being swept along with the flow. Fast flowing water can carry all sorts of debris, from small items, such as buckets and pebbles to much larger items, such as trees and cars, as was the case with Boscastle. If you can see it coming, that's all well and good, but if not, then all sorts can band into your legs under water. All the more reason for a makeshift walking stick. Stability when crossing water is paramount.

Arguably, the most important concern with sewer breaches is the contamination of the drinking water supply. In an urban context, this is much more likely than here in the country. During a prolonged urban flood, drinking water can become a problem. Very quickly, you can't use anything from the taps, and you certainly can't treat the flood water itself. The precaution of filling every available pot, pan, jug, kettle and definitely the bath with fresh water is a must. People in Tewkesbury were cut off for days before the authorities could get fresh water bowsers to them. Needing at least two litres per person per day, plus cooking and some washing water, it soon adds up for a family. With no fresh water, there's no tea, no dried food, such as rice, can be hydrated and nobody can wash their hands, which is also very important.

Chocolate River?
Back to Clovelly. With nobody in trouble and everyone who can stopping as much as they can from getting in and everything that could be put upstairs, thoughts moved to curing the problem. There were two choices ... decrease the input or increase the drainage. With the source a raging torrent blocked by  a pile of garden bits and bobs up against a gate, the plan was to get the drains working again. We didn't have any specialist equipment, so use anything we could, including hands, to get the silt and gravel out of the drains. We did best when we have the covers off, but couldn't leave submerged drains in that state. With the water now beginning to flow underground and with a few well placed empty beer barrels wrapped in a tent, we managed to divert as much water as we could. The area shown pretty much drained to nothing from knee deep with the drains were unblocked.

Communication was relatively simple in such a small place, we just walked to each other or shouted. In a wider area, the mobile phone is a useful tool, but watch the batter life. It's all well and good taking lots of pictures, but if you then need to ring the emergency services or other authorities, it's no good if it's run out of batteries. Modern smart phone don't last long at all, especially with all the wi-fi and Facebook monitoring. You'd think it was best to turn it off, but then nobody will be able to ring you. Better to turn off non-essential services, or have one of those old phone which can last eight days without charge and slap your SIM in there. Chances are, you've got one kicking about. Is it charged?

Another must in a prolonged flood situation is an understanding of what the weather holds. Of course, if the electricity and the land line is still working, then you can either watch the news or look it up on the Internet. If not, then maybe the mobile network. Other than that, you're left with the the radio. I have a wind up radio, which is nice for the beach, but also good emergency preparedness. In addition, during a major incident, the authorities will be broadcasting information on the radio via your local radio station, so you'll want that on all the time. A useful addition to the radio is a sticker with local radio station frequencies.

We are very thankful that that this incident did not occur at night. As our evening progressed, however, the electricity did blip a few times and I took a moment to locate my trusty wind up lantern, candles (with jars) and wind up torch, which also has a mobile phone charging attachment. Of course, your hardcore prepper will have their house wired up with a 12v LED lighting system and generator, but I'm quite happy with a head torch for most things. Some other considerations with electricity going off are that the fridge, freezer and electric cooker will fail. I have a wood burning stove, but also a camping gas stove, which would be handy, if we ended up living upstairs for a while. The best solution, of course, it to have a bit of food that doesn't actually need cooking. Many people store tinned soups and stews, which although nicer warmed, are possible eat cold from the tin, should the worst situation occur. Heat is a factor too. A gas bottle heater is a worthy addition to the prepper's household if no wood burner or open fire exists. Once again, consider the fact that you may end up living upstairs if it gets really bad.

As the water was beginning to ebb, it was clear that the worst had passed, but with speculation about further rainfall, we set to sandbagging the doors of houses, like mine, which only narrowly escaped breach. With this, we turned to the source of the problem. After a tonne or so of sand bags, we came to the rapid conclusion that we were fighting a losing battle. The sheer force of the river reroute had gone beyond our ability to fix without machinery and so with the light going, we decided to get home and prepare for the night. So a few of us went to the pub.

As it turned out, this was the end of our saga. We'd seen the worst and we'd survived. Being on such a steep hill and with the rain stopped some time ago, it was unlikely we were going to see any more problem. If we'd been lower in a larger valley, we'd still be expecting the rain from many hours ago to meet us at some point. If we here in a flatter area of more overt flood plain, then it might have been that the situation would escalate, with water rising and rescue coming by boat or helicopter as was the case with a chap who found himself stranded in his tractor in a flooded field in Holsworthy or with many residents in Boscastle. If you were to find yourself in such a situation, then do ensure that people know you're there. Makeshift flags are a good signalling technique here.

And so to the clean up process. Many people found that their cellar had been flooded and although now dried out, it was covered in mud which had been deposited by the torrent. Although inconvenient and in some cases financially damaging, it was not as bad as urban flood water, which can deposit sewerage and other nasties. On courses, when asked about where people would store their emergency provisions, many answered "in the cellar" or "under the stairs". The best place to put things you want in a flood is in the attic.

We will get back to normal in a short time and the river reroute will be dug out and reinforced. I'm proud to be part of such a tight and genuinely caring community, where disaster brought everyone out to help each other without thought.

Hopefully these tips will give you some insight into how to best survive a flood and although all of this is described in a domestic context, if found in a wilderness survival situation, maybe some extra consideration for camp placement will be given as what looks like a trickle of a stream today might be a raging torrent another.

If you have an interest in Emergency Preparedness, maybe check out some of the products available on Amazon. There are many more, but these are the ones I own or have used. They'll complement your first aid kit and fire extinguisher, which I'm sure you have already :)

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