Sunday, 20 January 2008

Flood Prevention & Protection in Morpeth

Next month (February), the Environment Agency (EA) will start consultation on flood prevention and protection schemes for Morpeth with a view to carrying out works in 2010. The last two proposed schemes were purely about flood protection – the proposal to build a 3m earth mound on High Stanners was rejected by local residents who preferred to accept the risk of flooding, while the concrete walls protecting Low Stanners look ugly and reportedly cause more problems than they solve by merely redirecting water.

This time, however, it sounds as though, the EA will be proposing more integrated plans – so I thought I’d just run over the causes of flooding as I understand them:
i) a sudden release of water – we’re going to get more ‘cloudburst’ style storms as climate change kicks in, but fewer heavy falls of snow with sudden thaws. Not much we can do about that either way – though if we reduce CO2 emissions drastically now, it won’t carry on getting worse for our great-grandchildren
ii) rapid run-off of water: if the ground is impervious – could be waterlogged or could be bone dry or could be covered by tarmac or concrete, then the water will run off rapidly rather than being soaked up and draining slowly. Several things we could do here:
a) don’t build huge areas of concrete or tarmac (like the new Dark Lane car park) without adequate soakaway (not just run-off drainage)
b) create ponds, watermeadows, marshland to absorb the water and slow the drain off. The Northumbrian Water works on Wellway include installation of huge tanks to hold back water when the Cotting Burn can’t cope with the water flowing into it.
c) plant water-loving trees like willows and alders along the river to soak up water (and absorb CO2) – though manage them to avoid branches etc causing blockages (see below)
iii) blockages in the drainage system, streams and rivers. Regular maintenance of storm drains and culverts is a must – any council that tries to save money by skimping on this sort of maintenance is penny-wise, pound-foolish. Litter – especially plastic bags – can be a major cause of blockages. Last year’s floods in Gloucester and Sheffield were made worse by plastic bags clogging the drains.
Debris from trees etc regularly cause blockages in streams and rivers – with the narrow Oldgate Bridge arches are a significant contributor to the High Stanners flood risk. Previous EA responses have involved drastic cutting back of trees along the river bank, but this can lead to erosion. Richard Cansdale is proposing a grid of ramps upstream which will strand tree debris as water levels rise, at a location where they could be regularly cleared.

So let’s see what the Environment Agency propose…

No comments: