Forumite

Reply To: Floods

#40860
Participant
Richard
@sawboman
Forumite Points: 6,517

Ed, we were both promoting the same idea. Delay the run-off from high ground via a variety of methods. Rushy, marshy paddocks, small streams with a series of gathering or settlement ponds, also equipped with rushes and the like to filter out the slit that otherwise gets dropped into the drainage system. Yes, outlets need to be wide and deep enough, and you do not want fast flow. This may mandate regular dredging activity to ‘harvest’ the mud. Sadly, and stupidly this is now usually classified as industrial waste. Historically, it was considered a rich soil improver that reduced the need to spread fertilisers. That was how the Somerset levels used to be maintained. However, dealing with it at the lower levels is a symptom of failure. It has to be managed from the very start of the flow. One way that has been experimented with is the use of otherwise useless straw bails at the edge of high run off areas to slow the flow right at the start. Seeding them with rushes and other powerfully rooted mesh style plants. Then digging, not filling in staggered, upper reach holding ponds with filtered outlets that allow slowed release of the water, but retain the rich, muddy sediments. This has been shown to ‘grow’ soggy, marshy, water retention ‘paddocks’ on such hill slopes where the restricted, water and vegetation egress helps to improve the land and equally valuably hold back the early arrival of what would otherwise arrive as flood water further down stream. Of course, it requires some intense, thoughtful planning and the sort of awareness that some in the environmental and river planning departments have been quick to forget and slow to realise