Last Friday, as I walked through the new shopping mall at Cardinal Place, Victoria with its vast area of glass roof, I said to myself: "The runoff from this place must be phenomenal." Less than an hour later the exceptional rainstorm arrived. Later that day photos on the BBC news website showed Victoria Street, Westminster transformed into a lake. Which proves my point, I think.
During the deluge itself I was in Embankment Gardens East, below the Savoy Hotel. I took refuge at the cafe there (a London treasure, but that's another blog). The waterfall gushing off the balcony roof was as if someone was pouring from a limitless bucket. When the storm passed, the tarmac path through the gardens was flooded, so I had to go along the Embankment, half of which had turned into a lake as well.
A pint of water weighs a pound and a quarter, as the rhyme goes (I don't know a metric version but I expect there is one - it probably should be in French). A large volume of water is, therefore, amazingly heavy, and destructive. Glass, concrete and tarmac everywhere: no wonder the runoff of water we are getting is so violent. We know that impermeable surfaces make it worse, yet we go on adding more. Practical wisdom, not. Truly we are a crazy species.
Another barmy thing we people do is deforestation. I first started worrying about this when I learned at school about the tragic flooding of Lynmouth in the 1950's in Devon, generally thought to have been caused by earlier deforestation. Yet loss of woodlands has carried on apace and still is. Crazy.
I'd vote for an urgent national policy of replanting deciduous woodland on all our high ground, to help soak up rain and prevent topsoil being washed away. I support the Woodland Trust, but a charity doesn't have the powers or resources to do much when private landowners won't and government is failing to act.
And I would never, ever buy a home on a flood plain, or advise anyone else to. No way. Gordo and property developers please note.