After another few days where there were countless TV, radio and other reporters describing in mind achingly boring detail the rise and fall of flood waters, this time throughout south western and Welsh Britain I find myself re-asking this question. My answer is sadly blurred.
This is because there’s truckloads of human stupidity, spread out all over our flood-plains for a start, which tend to mask the impacts of underlying environmental alterations. I guess, though, it’s logical and methodical to clarify what I mean by “truckloads of human stupidity” before returning to phenomena, impacts, arising directly from climatic change.
The latest series of events have been, I think, all post cloud dumping of, typically, “a month’s rain in two days”. They always say that unqualified. In a year a location might have, say, a metre of rainfall. Although this then works out at about 8.4 centimetres per month it never falls spread out like that. There are wet seasons – October, November, February, early March – and dry seasons – say April til September. Most of the rain falls in the wet months and we are used to that.
But a number of things have changed and it seems clear that the time between rain falling and flooding events has shrunk. It’s also clear that there’s more and more hard surfaces which simply shed water fast downhill. Upland grazing of sheep keeps the sward to an absolute minimum. Of course so much channeling and ditching are always being improved, as well.
It is illuminating to consider the volume of a five centimetre downpour. Over one square kilometre there falls 50 000 tonnes of water, a volume, of course, of 50 000 cubic metres. A block 100 metres by 50 metres by 10 metres. Sorry, I labour the point but, if it cannot sink into the ground, and recently very little has been able to, then that’s all got to get to the river systems. Frequently then there are points in the ditching/piping which cannot carry a sudden bulk like this and chaotic flooding ensues.
It all ends up on the flood plains, yes, but sudden torrents like these can cause damage on the way down, too, flowing into back yards and out through the living rooms. This seems to have been the case in Snowdon’s foothill town of Llanberis this week – overflowing torrents cascading downhill independently of the stream, ditch and piping systems. As this is some one hundred square kilometers catchment area that was five million cubic metres of water through one small town in 48 hours.
The more we fix the bottleneck points, the faster water will reach the rivers and the more flooding of “flood plains” will inevitably occur. Multiply up Llanberis’ problem last week to major, downstream situations and the bulk of water is immense. The better we drain the uplands, the worse will be the impact of flash floods as that water is accelerated to the lowlands.
Silting of the entire river system with soils washed away from field systems exacerbates these problems, too, as well as leaving flooded houses caked in a deep layer of mud, when the waters recede. Llanberis looked like a recently ploughed field!
Of course it needn’t be like this. Downhill, lowland areas have undoubtedly seen developments in highly questionable locations and the concomitant increase in the downhill velocity of the rainfall has compounded this problem. But we do not wish for the water to disappear out to sea as fast as possible for, when the rains relent droughts can quickly set in – increased water use, evapotranspiration from the land and still fast flowing land drainage systems.
Upland woodland and undrained bogs and mires retain moisture and slow its progression to the sea. Woodlands further downstream also build deep soils, ideal to retain moisture as well as impeding its flow downhill. With deep root systems trees break up the subsoils and allow surface rainwater to seep down into the lower rock strata, to recharge aquifers and allow wells to flow at considerable distance away.
So much of this has gone today which further compounds the downhill problems – the last fifty years seeing increasing upland drainage and only ever planting ranks of rank conifers, with ditches spewing out highly acidified, toxic effluents into the river systems.
A few years ago the Cornish coastal village of Boscombe was dramatically flooded with a colossal torrent wreaking havoc as it forced its way through the narrow high street. “Once in a hundred years – a freak incident” they all said. Two years later it happened again and, like as not, it was bad this week. It has a group of tors surrounding it, each grazed incredibly short, drained to improve the grass yields and lacking in any woodlands. Any heavy rain and it is bound to flood and this will continue until the uplands are restored.
Restored to native, deciduous, deep soiled, ecologically diverse, rich and actually almost certainly far more productive as a food growing resource than they are now. Yes and that will require more people to carry out the range of activities to culture and gather this food – not just one jaded shepherd per thousand hectares, not seeing a soul from day to day as he picks up dead lambs and dead ewes until he, too, is picked up equally dead having broken under the strain and the loneliness.
So you can see why I prevaricated at the start. With all this human folly, how can we look at the effects of climate change? There’s been a huge “See, we told you so” campaign by climate activists in the USA, based on the fact that they’ve had a huge amount of events – floods, storms, sandy hurricanes, whirlwhinds, Mary Poppins events, you name it! We got nothing compared with that lot. And last year, even earlier this year, we had “conclusive drought” conditions. “See, this drought proves it” people would say, meaningfully.
There are Met Office data for rainfall going back maybe 200 years. Perhaps we can show something there. There must be people examining these data – mustn’t there? I like to think that I imagine I can see that there’s simply “more weather” but, in truth, I maybe just HEAR of it more – 24 hour news reporters got to talk about something, after all!
With increased solar energy gathered by and locked into the atmosphere by the accumulation of concentrations of greenhouse gases over and above that which naturally reside there, elevated temperatures, increased turbulence and more rainfall from extra evaporation seem inevitable. We cannot with any certainty predict how such forces will play out.
Regardless, we still should restore our native, natural, water management system – replant our upland woodlands and put other, lowerland marginal acreages down to trees. It’ll help us all live better, buffer our water courses and work against atmospheric carbon accumulation. Just to be on the safe side!