Prince Charles & The Uckfield Floods
By Paul Homewood
We await with gleeful anticipation what dreadful nonsense Prince Charles will include in his new book for the Ladybird series.
But if the front cover is the best example of the perils of climate change he can come up with, he might as well not have wasted his time!
The cover represents the Uckfield floods in October 2000, hardly a recent event.
The Geographical Association have published a detailed Case Study of the floods, which relates how the town has suffered from regular floods in the past, with the first recorded in 1852. More recent floods have occurred approximately every nine years: in 1962, 1974, 1989, 1994, 2000 and 2007,
The Case Study notes how the hydrology of the town exacerbates potential flooding problems:
Downstream (west) of the High Street, the Bellbrook Industrial Estate and the Bell Walk shopping area were built within the floodplain, as far downstream as the A22 Uckfield bypass. This commercial development has largely blocked the natural floodplain, leaving only a relatively small river channel through the town.
The flooding in October 2000 was influenced by the channel morphology of the River Uck. The channel of the River Uck changes in size and shape as it passes through Uckfield. As it flows into the town the river passes through a historic mill, flows under the town centre railway bridge and then under the High Street road bridge.
Upstream of Uckfield
- Upstream of the town, when the river channel capacity approaching the Mill is exceeded, the river flows onto the floodplain on the right bank through a bridge under the railway. This overland flow rejoins the main river channel at the railway station and the whole flow of the river passes under the High Street Bridge.
High Street area
- The flood plain ends abruptly behind the High Street shops. If there is too much water on the flood plain, when flow through the town reaches about 48m3/s, some water starts to flow down a passageway alongside the supermarket into the High Street.
- If the water flow continues to increase, the road drainage can no longer cope. Water then starts to pond up in the High Street and when the flow reaches about 55 m3/s it starts to flood the shops on either side.
- During a major flood, only a limited amount of water can flow under the High Street Bridge. The remainder flows across the High Street and down roads and passageways before eventually returning to the river.
The floods occurred after 150mm of rain fell overnight, following four days of heavy rain.
According to the Case Study:
However it is very difficult to estimate reliably the large floods that occur on average once in 100 or 200 years. Newspapers and other reports of flooding over the last 150 years have been used to try and compare the 2000 flood with other large floods since 1852.
This evidence suggests that the flood of 2000 might be expected on average once in around every 200 years, or put another way about a 0.5% chance of occurring in any year.
But what we need to bear in mind is that Uckfield is only one small part of the country. The odds are that somewhere in Britain will see a 200 year event once in a while.
For instance, according to the Met Office, the record for 24-hour rainfall is still 279mm recorded at Martinstown, Dorset in 1955, well above Uckfield’s rainfall.
Other short term records set in southern England are comparable, such as Maidenhead (1901), and Hampstead (1975).
But perhaps the most direct comparison we have are the September 1968 floods, which hit Surrey particularly badly, but also large parts of the Home Counties as well.
Leading meteorologist, Philip Eden, describes the event as probably the most severe inland flood to hit the Home Counties in the last 100 years .
Things were worst on the Monday and Tuesday by which time water covered roughly 280 sq km of land – that is the equivalent of one-sixth of the area of Surrey – and some 25 thousand homes were flooded.
Indeed, Surrey suffered more than any other county. In Esher alone roughly eight thousand houses, roughly one-third of the urban district’s housing stock, had water damage, and a further four thousand properties were similarly affected in the adjacent towns of Walton and Weybridge, Chertsey and Addlestone, and Woking. In Guildford, town-centre shops were flooded to depth of 2.5 metres.
Several road and rail bridges were badly damaged; six of these suffered major collapse and subsequently had to be completely rebuilt. Most of the main roads taking traffic south and west from London were blocked for at least 24 hours (some of them for three days). Farmers suffered considerable losses too, especially those with root crops, although the cereal harvest had been completed by the end of August.
The floods were the result of a prolonged downpour which lasted for the best part of two days. This in turn was caused by a vigorous depression which had become stationary over France; two contrasting air-masses – a very warm and very moist one which had originated over the western Mediterranean, and a cool moist one from the Baltic Sea – converged over southeast England, and the line of convergence moved very little during that astonishingly wet weekend.
This weather pattern bore some similarity to the one which prevailed across Essex, London, Surrey and Hampshire last week (on Tuesday 15th) although this year’s event was at least two orders of magnitude less severe than the 1968 event.
Then, a broad belt extending from the New Forest to the Thames Estuary received over 75mm of rain. That is the equivalent of six weeks’ worth of rain in less than 48 hours. Some 75mm also fell in a much narrower belt along the line of the Chiltern Hills from south Buckinghamshire across Hertfordshire to west Suffolk. A sizeable are covering much of Surrey, west Kent, southeast London and south Essex was deluged with more than 150mm of rain, and two rainfall-recording sites in Essex – Tilbury and Stifford – received slightly more than 200mm, which is more than they had had during the whole of the summer quarter.
Note that the rainfall totals were comparable with Uckfield’s, though over two days, but also a much wider area.
Floods have occurred since time immemorial, and there is very little evidence that they are becoming worse.
Perhaps if Charles had asked bothered to ask proper experts like Philip Eden, rather than an environmentalist or a dishonest junk scientist, he might have avoided making a fool of himself.