By David Dennis

How good are humans at seeing what might go wrong in their schemes? In the past few days there have been several flood warnings issued by the Environment Agency via the BBC Weather pages. They detailed the likelihood that the Powdermill Stream would flood Crowhurst Cricket Ground and local housing, and that the Combe Haven river might flood not only Bexhill Road recreation ground but also adjacent housing. 

A plan to ensure that the Tier 1 housing site on Bexhill Road inside the Countryside Park boundary does not flood is being designed by specialist environmental assessors, Ambiental. In draft, it includes mention of a non-return valve, large bunds or banks to stem floods, and extra ‘ponds’ to be engineered. The nominated sites for these ponds show that they are in places where the ground is already flooded regularly. These sites are full up now, so something seems wrong with that general concept. You can’t pile water on water.

Current flooding at Combe Valley
PIC: David Dennis

Some people in Crowhurst are concerned that Ambiental-led action to save the Tier 1 site for a housing estate on the natural 12,000-year-old flood plain, will cause the Combe Haven valley annual flood to rise so high that it backs up into their village in mid-winter, when rains are at their heaviest. Is this possible? 

Having walked every inch of the 1066 Trail and Bulverhythe paths through the floods (wearing shoulder-high waders), I can see their cause for concern. The Powdermill stream runs past, not into, Crowhurst Lake. It is just a level-bedded shallow stream in summer with many Beautiful Demoiselles (Calopteryx virgo) gracing it, which flows out into the Combe Valley in a separate channel. Around halfway down the valley it joins the main Combe Haven flow. It has no rapids or falls, and water moves at a slow rate.

Once that river rises, as it does each winter, then the whole valley is flooded to a depth of several feet. This may slow the exit of water from Crowhurst. I cannot state that it will back up and flood Crowhurst for certain, but what I can say is that at present there does not seem to be any planning for that event within the overall pre-planning actions being taken by Hastings Borough Council. 

Admittedly the horse-riding and cycle track greenway looks clear of potential flood on higher ground. It seems to protect Crowhurst. But that is a false sense of security, because the water in the Powdermill is hidden down in a ditch well below the greenway when it passes under the by-pass bridge. The valley is now flooded right to that bridge. I have asked for comment on the final Ambiental plan and the implications for Crowhurst but have not had a reply. 

Almost all council activity is currently halted by the General Election we all know and some love. So we will have to be patient and wait until January 2020 for 20-20 vision on local flooding. In the meantime, keep checking the flood warnings. Human errors are often made by not fully understanding the forces of nature.

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