Floods in Somerset have, up to now, seemed far removed from our own back yard. But with thousands of homes by the upper parts of the River Thames now at risk of flooding I wondered how safe we were from our own rivers.
A look back through the reference books show the geography of the Roding and Lea Valleys has made the area prone to inundations for hundreds of years.
In January 1809 the lower River Lea burst its banks in several places following a deluge that dumped two inches of rain in the space of 24 hours. The rain abruptly ended a snowy cold spell that had begun over a month before in the middle of December. From Luke Howard’s readings it is likely that up to half a metre of snow had fallen in the previous weeks in the upper parts of the surrounding countryside with only slight thawing. With the frozen ground unable to absorb any of the rapidly melting snow and rainfall the amount of water flowing downstream must have been immense. Howard takes up the story…
“The River Lea continued rising the whole of the 26th… The various channels by which it intersects this part of the country were united in one current above a mile in width which flowed with great impetuosity and did much damage.”
Howard, his chemical factory located on the banks of the river Lea close to what is now Bow flyover, wrote at length about the event, his account replacing the usual brief notes about daily weather in his book The Climate of London.
He talks of embanked pasture land being “filled to the depth of eight or nine feet” and people driven to their upper rooms relieved by boats plying under the windows.
“The Thames was so full during this time that no tide was perceptible.” It took until February 23rd for things to return to normal.
Miraculously no lives were lost in the flood and cattle “by great exertions” were saved by being kept in their stalls. Howard, saying that the flood could have been far worse, believed a neap tide, strong westerly winds urging water down the Thames and mild weather helped avert a tragedy.
Howard’s statistics of the previous months show that the second half of 1808 were wetter than average – though not especially so. And nothing like the rainfall we have had this winter. From December 1st until February 8th Howard recorded 130mm of rain, which is about 100mm less than what I have recorded this winter.
This fact alone shows just how much the nature of the river has changed in the last 200-odd years thanks to spending on flood defences.
Work to improve the defences was prompted 67 years ago when similar catastrophic flooding came with the thaw that ended the severe winter of 1947, one of the coldest winters in recorded history and an episode remarkably similar to what Howard recorded in 1809.
The Lea Valley, along with many parts of the country, saw some of its worst flooding in a generation. The river burst its banks at several points bringing misery to surrounding communities. Valleys turned into lakes in 40 counties and East Anglia’s fens were a sandbagged inland sea. More than 100,000 properties were damaged and, then as now, heroic battles were fought by the military to keep water-pumping plants and power stations dry.
The sense of crisis was felt worldwide. Canada sent food parcels to stricken villages in Suffolk; the prime minister of Ontario even offered to help dish them out.
The River Lea Flood Relief Channel, that flows between Ware, Herts, and Stratford, took almost three decades to complete. The channel incorporates existing watercourses, lakes and new channels. Since it was completed in 1976, there have been no major flood events in the Lea Valley, although there have been three occasions when the river system was full virtually to its capacity: in 1987, 1993 and 2000. Since its completion, the level of protection afforded by the structure has declined, so that in some areas it offers 2 per cent protection, and in some, only 5 per cent protection. The Environment Agency published a strategic environmental assessment in 2008, which looked at ways to maintain the flood defences in the Lea Valley.
It remains to be seen whether we will see any flooding in Redbridge – a further 40mm of rain is forecast to fall up to Saturday morning. As well as the problem of rain there is also the issue of the water table which in the past week has risen to the surface in places. Inland lakes forming on Wanstead Flats have seen the cancellation of football fixtures and a couple of people I’ve spoken to say standing water has started to appear in their cellars
It is all too easy to blame the Environment Agency for the current flooding in Somerset and elsewhere but the meticulous planning by its forerunners brought, at least to date, an end to the widespread flooding problem in the Lea Valley.
As the government struggles to find a solution to the current problems with flooding it would do well to look to the grand schemes of the past and forget about any planned cuts to flood defences.