After the storm...time to prepare for the next one
Storms Desmond and Frank and their aftermath once again underline the importance of thorough risk evaluation and flood prevention, says Harry Lukas.
Property owners have had a wake-up call in the form of this winter's unprecedented storms, which brought more than a foot of rainfall to the worst-hit places.
Among the areas affected were southern Scotland, Aberdeenshire, parts of Northern Ireland, north Wales and especially north-west England.
Floods are usually caused by heavy rainfall and water courses of all types being unable to cope, with debris causing blockages and erosion diverting normal flows.
There is much property owners can do to mitigate the effects of flooding by assessing the risks and keeping up with maintenance.
Low-lying and poorly drained land and the buildings on it may be more prone to extreme weather events, and it's in these places that the problems are most obvious. There are however many properties that up to now have not been affected but where just a little more water might tip the balance and cause lasting damage.
Taming the Tweed: Three views of the River Tweed at the B712 crossing...during the New Year 2014 flooding, on December 12, 2015, when the river rose dramatically from Storm Desmond, but new defence works saved the road, and on December 30, after Storm Frank broke through the defences.
A quick assessment of how water runs around a property, whether a building or land, will give pointers as to where potential problems lie. Simple actions such as cleaning ditches, drains and gutters regularly will help, but seeing where water could divert or run off may also highlight opportunities to take preventative measures before the worst occurs. We can assist with arranging risk assessments.
As an example, farmers and local authorities linked up to prevent high-risk flooding on a small section of the upper Tweed village of Drumelzier, which was regularly cut off and some houses put at risk when the river rose above a certain level.
The works involved two bunds - built-up flood banks - one where river erosion directs high water into a field so the run-off crosses the road at up to five feet in depth, and the other protecting the low-lying roadway. The field between is still allowed to flood but without the significant effect on the road and community. Storm Desmond was the project's first test and it passed with flying colours. Frank produced new record levels and proved too strong for the bunds.
Where villages and towns are affected, barriers tend to be more easily over-whelmed, so flood water needs to be managed in a way that can restrict or divert the amount of water trying to pass through a narrow exit.
This work becomes highly technical and expensive and responsibility lies with the local and national government. Still, any property owner must take stock and see what mitigation might reasonably be applied in respect of their own property.
In almost all cases, the costs of reinstatement and recovery of lost or damaged property together with the time taken in coping with the problems far outweigh the process of minor prevention works.
That said, the Desmond and Frank deluges were far in excess of any records, and so we must adjust our view of the worst-case scenario.
*Originally published in Energy Matters Issue 11 Spring 2016