1947 Thames flood

The 1947 Thames flood was the most severe flood of the River Thames in the 20th century, affecting much of the Thames Valley as well as elsewhere in England during the middle of March 1947 after a severe winter. The worst in over 100 years, it was exacerbated by an extremely high tide.

Background
The source of the Thames is in Gloucestershire, and it flows east through Oxfordshire. Records have been kept of its water levels since 1893.

In January 1947, the country—particularly the southeast—had been hit by blizzards, which were severe enough to freeze the upper reaches of the River Thames. Winter storms continued into February. Before the flooding, 117 mm (4.6 inches) of precipitation and snow had fallen; the peak flow was 61.7 billion litres of water per day and the damage cost a total of £12 million to repair. The heavy snow had been followed by a period of relatively warm weather, which caused the snow to quickly melt on top of the still-frozen ground, which meant it had nowhere to drain. War damage to some locks made matters worse. Maidenhead was particularly badly damaged, with over 2,000 dwellings flooded. The same weather conditions caused widespread flooding to many river basins in the country during March 1947. Although there were no deaths as a consequence of the flooding, the shock value was sufficient to put flooding on the political agenda.

Aftermath
Other significant Thames floods since 1947 have occurred in 1968, 1993, 1998, 2000, 2003, 2007 and 2014.

Following the 1947 flood, a recent commentator has suggested, the Borough of Windsor and Maidenhead—having been particularly heavily hit—"judged that the zoning regulation after 1947 would cause the area to become derelict and destroy its amenities".

It is considered a 1/60 year-occurrence event.

The flood of 1947 is considered as being instrumental in formulating major government policy developments regarding flood control.