Memorandum submitted by Bill Sherwood
(FL 132)
Letter from W Sherwood to David Taylor
MP, Committee Member, 3 September 2007
I was interested to read your "The Commons
Touch" piece in the Ashby Times this week. I'm no
engineer, but I've had a few thoughts on the complex problems
of flooding and its avoidance.
Increased and faster run off as a result of
development is clearly a significant factor, especially for locations
downstream. Similarly some flood avoidance schemes appear to facilitate
a quicker dispersal of water in some locations resulting in problems
further downstream. Residents in Selby have blamed flooding they've
experienced on the protection work carried out at York for example.
It seems that the run off of water must be retarded to at least
reduce the flood surges that we have experienced recently by:
1. Designing buildings to store rainfall
for supplying suitably filtered water for non-drinking quality
uses—toilet flushing, car washing, dish washing, clothes
washing, bathing and showering etc.
2. Designing retarding reservoirs into building
projects (including roads) so that significant quantities of water
can be held back at times of excessive rainfall and subsequently
released in a controlled manner when appropriate.
3. It may be possible to predict severe rainfall
sufficiently in advance to enable water companies to lower reservoir
levels in advance in a controlled way so that the same reservoirs
have capacity to absorb some of the surge water when it arrives.
Alternatively, if we can rely on higher levels of rainfall, reservoirs
could be maintained at lower levels to enable take up of flood
surges.
4. Ensuring that new developments are sensitive
to existing natural drainage and watercourses, avoiding the temptation
to straighten channels or "improve" banks with concrete
and steel that serve to speed up water flows.
On the other hand, it seems that the demand
for development land will mean that projects will continue to
be carried out in flood plain areas. If this is the case, then
thought will need to be given to building design to mitigate the
effects of intermittent flooding by raising the current ground
floor levels above predicted flood levels, not forgetting to raise
garage, car park and road levels too.
As for areas affected by regular flooding like
Upton on Severn it is difficult to see what can be done in the
short term. It's all very well to suggest diverting water away
from residential and commercial areas to where it will cause little
or no damage but is there capacity to do this effectively without
affecting livelihoods in the agricultural community? If flood
plains in agricultural areas are reserved for grazing rather than
arable use then maybe this would provide some of the answer by
deliberate flooding of selected areas, but this would require
barrier controls on rivers to facilitate this. I also wonder what
we can learn from flood control in the Fens. I recently visited
Denver Sluice near Downham Market which is a major piece of waterway
engineering that enables diversion of significant volumes of water
to Essex when required, the beginnings of a national water grid
perhaps. Could similar schemes in different terrain be feasible
elsewhere in the UK?
As for rising sea levels, we can surely learn
much from Dutch engineers who had so much to do with the successful
draining of the Fens in the past.
Bill Sherwood
September 2007
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