September 2006 Weather tips

A risk of flooding ahead?

Last month we discussed the risk of flooding due to high rainfall, noting that
periods when hot dry weather predominates are often followed by wet unsettled weather, causing local flooding, such as in 1947 and 1975. Indeed it seems that for many parts 2006 has repeated this pattern; up to 200% of the average rainfall fell in August over parts of East Anglia giving local flooding, bringing rather too much of the needed rainfall in too short a period.

This month our attention need turn to flooding again, though of a rather different sort. During September and October we are expecting to see some of the highest tides for twenty years in places. The cities of Hull, Portsmouth and Cardiff have been recently named as being at especial risk but many other areas are also implicated, particularly resorts down the East coast. Scientists have made the point that as sea levels rise due to Climate change and the fact that the 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 is recognized by the Government as spending has increased on flood defences by 35 per cent (in real terms) in the last ten years.

Key dates in the next few months are the 9th-11th September and the 7th-10th October. Whilst a period of relatively calm weather will be unlikely to cause any problems, if there is the risk of a storm surge caused by deep low pressure during these periods then there could be more cause for concern. 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.
For those living on estuaries and river plains the danger can come 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.
As with flash flooding if you live in a prone area for coastal, river or estuary flooding it is as well to be prepared for the possibility of such eventualities.

• Check the Environment agencies website (below) to see if 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.
• Check your local tide timetables to see when the highest tides are expected and listen to local weather forecasts closer to the periods in question. You can find the tables at this site http://www.pol.ac.uk/ntslf/tides/ carrying 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.
• As mentioned last month, 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 make up sand bags in advance, using cloth or plastic sacking.
If coastal flooding occurs as with the procedures for flash flooding
• 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 gas and electricity supplies if possible, 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 pr 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.

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, the guidance to prepare 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, can still 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/subjects/flood/