Summer 2008 Flooding
After the wet periods we saw in July it may have seemed that after July's last week or so when the sun shone that all the rain was behind us. Sadly that doesn't look to be the case with a lot more wet weather looking set to come in August.
We look to be entering a period when the jet will take a rather southerly course, steering depressions on a quite southerly track across the southern UK, with high pressure still established over the area from Iceland down through northern Scandinavia. north . As this means the track is over warmer water then the amount of moisture held by such depressions tends to be greater and as they reach the UK, blocked by high pressure further east they slow down, and release copious amounts of rain across us, especially if thunderstorms develop as well.
Summer rainfall is not especially useful generally as it tends to run off the soil rapidly without sinking in and so does not increase the water table in the long run. Equally, it can cause flash flooding where large volumes of water pile up and cause damage, both to crops in rural areas and, of more concern, across urban areas especially in valleys and near to floodplains. Given this possibility it is as well to be prepared for such eventualities. If you think you are likely to be affected by flash flooding then you should take precautions before the event if possible.
You can purchase flood guards and flood gates in advance which you can lay around your property. If your home is regularly at risk of flash flooding these really can offer worthwhile protection. Alternatively you could make up sand bags in advance, using cloth or plastic sacking If a flash flood occurs. Move elderly people and animals to safety first then alert others. Ensure sandbags are in place and plug up sinks and baths putting a sandbag in the toilet bowl as well. Turn off the gas and electricity supply, unplugging electrical items and moving them upstairs or into loft space if time permits.
Don't try to walk or drive through the floodwater unless told to do so by the police or other agencies. It only takes six inches of fast flowing water to knock you over. Just two feet of water will float your car. It may also be contaminated with debris, silt and sewage.
As the Environment Agency point out, flooding often happens very quickly and when you least expect it, such as in the early morning, when it’s dark. They suggest that preparing an emergency flood plan can help you through a serious situation; by creating the plan with all the members of your family, explaining what to do and even practising the plan, it will help prepare everybody for the time when you may need it.
For further information see the Environment Agencies website at: http://www.environment-agency.gov.uk/homeandleisure/floods/
Added in September 2008
Yet again flooding has been making news headlines during August with large areas of Northern Ireland seeing 60-75mm falling in a short period around August 16th, causing a lot of damage locally. As well as this rainfall was around twice the average generally across England and Wales last month, repeating the patterns we saw during June and July 2007 in the south and Midland, during August 2007 in the NW of England and indeed back in August 2006 when as much as 200% of the average rainfall fell across large parts of East Anglia, bringing local flooding (though that followed a drought in the previous few months and was much needed, something we cannot say about the last few Augusts). A lot has been learnt from the floods of 2007 in particular about coping better with such eventualities.
This month our attention may need to turn to the risk of flooding again, though of a rather different sort. Programmes on the tv recently (in particular that narrated by Andrew Marr) have continued to well make the point that as sea levels rise due to climate change and the fact that the east & south east is slowly sinking, the possibility of flooding caused by storm surges, high tides and heavy rain is likely to worsen further into the 21st century. This year the period around the 1st September and 15th/16th October sees very high tides in places, though it's the south west and South Wales mainly at risk in September, whilst in mid October there is a rather more widespread risk.
As always, whilst a period of relatively calm weather will be unlikely to cause any problems, there are two key factors which can increase concern. One is the risk of a storm surge, caused by deep low pressure near the UK during these periods. In the south the danger tends to be from strong south-south westerly winds, for a period from a few days before the high tides; along the east coast it tends to come when low pressure is situated in the North Sea (the lower the pressure the higher the water rises at high tides) with a strong N-NE’ly flow down the east coast. The second is the risk, especially to those living on estuaries and river plains, when large amounts of rain have fallen in the week before the highest tides, allowing rivers to be in spate, possibly already flooding the flood plain areas. Strong incoming tides then ‘back up’ this water, allowing further overflow and spillage into low lying areas.
There are several good sources of information online that can help you assess your own home or areas risk of such flooding. The Environment Agencies website will tell you are at risk of coastal or estuary flooding. Large scale maps allow you to note quite accurately whether you may live in an area that is potentially at risk. These also carry colour coded estuary related flood warnings. The Proudman Oceangraphic Institute carries a choice of ports close to your area. Remember, that the tables do not make allowances for the weather conditions however. Bad weather on the day could increase the heights expected substantially. The EA's floodline information service is on 0845 988 1188 or can be viewed at www.environment-agency.gov.uk/floodwarnings . It is updated every 15 minutes. Around the south east, south and south west coasts you can use the excellent Channel Coast Observatories website to look at real time tidal gauge information also just here.
As we have mentioned before you can purchase flood guards and flood gates in advance which you can lay around your property. If your home is regularly at risk of coastal flooding these really can offer worthwhile protection. You can also make up sand bags in advance, using cloth or plastic sacking and if possible store them in your garden if you have one.
One key point that is worth reiterating again, is not to try to wade or drive through the floodwater unless told to do so by the police or other agencies. It only takes six inches of fast flowing water to knock you over and a few feet of water will float your motorbike or car and it is often difficult to know how deep the centre of the flooded area may be, as you advance. This was much in evidence in the recent flooding in a Belfast underpass when many drivers carried on down into the underpass - partly as a result of peer pressure from drivers backed up behind them; the result of course was loss of steering control and many flooded carrol. It may of course also be contaminated with large debris, silt and sewage.
At least with coastal flooding the Environment Agency now has good warning systems in operation, introduced after the disastrous East coast floods of January 1953, so that an alert is likely to be raised more rapidly than for flash flooding. Nevertheless, its worth saying again that the agencies guidance on preparing an emergency flood plan which can help you through a potentially serious situation with the members of your family, explaining what to do and even practising the plan, will still help prepare everybody for the time when you may need it, so it is worth revisiting it now.
