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The Lynmouth Floods 1952
 
Meteorological Phenomena
Topography
Rescue Effort
Social Consequences
Economic Consequences
Environmental Consequences
Redevelopment
Videos
 
         
         
 
 
Meterological Phenomena
Synoptic Chart
 
Rainfall Hydrograph
 
  • Drought had effected most of southern England during the second half of July 1952. Source
  • Conditions broke down at the beginning of August to be followed by a period of changeable weather over the whole country. Source
  • A depression had formed in the mid-Atlantic three days prior to the 15th with a central pressure of 1016 mb and then subsequently moved east-south-east. Source
  • Although this depression had no frontal structure, warm air from France was drawn into the circulation as it approached Brittany. Large moisture contents in the air around southern England combined with the warm thundery air from France indicated a high possibility of thunderstorms breaking out anywhere near the track of the depression. Source
  • Continuous rain began at the Scilly Isles and at Culdrose in the early hours of the morning and spread to all parts of Devon, Cornwall and Somerset by midday. Source
  • Cold, moist and unstable air ascending up the northward facing slopes of Exmoor introduced more moisture into the already heavy raining area. This may well have been decisive in producing the excessive rainfall in the Lyn catchments. Source
  • Heavy periods occurred during the afternoon with brighter intervals. The first exceptional downpour occurred after a darkening of the sky between 15.30 and 17.30 GMT Although reports vary, torrential rain occurred during 18.30 and 22.30 GMT, easing off to rain of little importance in most places at approximately 02.00 GMT on the 16th. Source
  • As a great deal of rain had fallen on the catchment during the previous two weeks and the evaporation during the day of the flood was negligible, the permeability of the surface of the area was minimal. The storage capacity of the vegetation, peat or soil and rocks was taken up by the rain which fell prior to the 15th, leaving no opportunity for infiltration to occur. Source
  • A quote from the news at at the time: 'The flood followed yesterday's torrential rain. In the 24 hours before, some nine inches (22.9cm) of rain had fallen on Exmoor, just four miles (6.4km) away.' Source
 
Topography
Lynmouth Topography
 
  • The catchment area of the Lyn rivers totals 102 sq. kilometres, much of which is plateau drained by steep sided combes. The plateau is covered in parts by moorland grasses growing from wet, peaty ground and in others by heather and bracken on well drained soils. These soils do not extend much further than 1.2 metres deep. Source
  • On the smooth, convex hills there were few storage dips and ponds, and this capacity would have quickly filled after the first rains. When the soil profile becomes completely water-logged, saturation excess develops into overland flow or surface runoff. Source
  • While the average velocity of flow may have only been a few centimetres per second over the summit, by the time it had travelled tens of metres before reaching a stream or the edge of the moor it would now be travelling at 3 to 6 metres per second and at a depth of several centimetres. This may well have taken as long as two hours. Source
  • As the valleys were narrow and deeply incised there was little room for flood storage, the result being that the waters were confined to the narrow river channel. Source
  • The Devonian sandstones break up into boulders of all sizes, including smaller fragments and sand. Transportation is minimal during normal flow conditions, yet during flood conditions much material can be moved and the valley sides are loosened up, allowing this material to be carried away by the following floods. Source
  • Bridges trapped boulders and trees causing temporary dams which later 'broke' causing a 12 metre high wave to travel downstream at 30km per hour.
 


Rescue Effort
  • The local policeman, Derek Harper, who had only recently completed his training, was awarded the George Medal for the part he played in rescuing people from the flood. Thirteen other local people received lesser awards for bravery. Source
  • Two police constables were on duty in Lynmouth on the night of the 15th. A third returned to duty as the events unfolded.
  • Walkie-talkie radios had to be collected from Bristol to be used during the rescue and repair phases.
  • Two fire brigade teams were based in Lynton and became fully involved in the rescue efforts.
 
Social Consequences
Dead 34
Housing and Buildings destroyed 38
Houses and Buildings damaged, requiring demolition 55
Houses Damaged 72

Source

  • 1000 people left homeless. Source
 
Economic Consequences
Housing and Buildings destroyed 38
Houses and Buildings damaged, requiring demolition 55
Houses Damaged 72
Roads and Farm Roads damaged 110
Bridges destroyed and damaged (private & public) 28
Caravans 4
Motor coaches 1
Lorries 2
Motor cars 20

Source

  • The flood's devastating effects upon buildings and bridges occurred in two ways. Firstly, direct battery was accomplished by the sheer weight of the flood waters and its load of trees and boulders pounding against the artificial structures. The second way of property destruction was the undermining of structures that were built on easily erodable drift deposits. Most of the ruination of houses and bridges was due to this undermining action. Source
  • The building of the harbour, roads, bridges and river realignment work in Lynmouth took four years, at a cost of £725,000, funded by local and national government. The £1.3 million raised by the North Devon and West Somerset relief fund was distributed to the 1710 people who suffered in the disaster. Source
 
Environmental Consequences
  • Although a large amount of debris was carried out to sea, a considerable amount was deposited on the river beds, which were raised from 6ft to 10ft above their original levels. Source
  • The West Lyn River had been diverted and its channel made narrower due to the building of tourist accommodation and amenities. It flowed through a narrow culvert. During the flood the West Lyn changed direction, back to an old course, causing a 'triangle of destruction'. Source
 
Redevelopment
Plan of Lynmouth Before the Flood
 
Lynmouth Today
  • Reconstruction took several years. Plans were drawn up and a model produced, which was used for public debate. Source
  • The opportunity was used not only to reconstruct but to plan for Lynton and Lynmouth's future as a tourist resort and to cater for the motor car. Source
  • Roads were widened and new car parks created in both settlements. Source
  • It was necessary to completely rebuild the harbour wall. The harbour wall was constructed over sheet steel toe piles driven into the ground to prevent any possibility of scouring. It was then constructed of concrete faced with local stone washed down in the flood. Source
  • It was also necessary to rebuild the Rhenish Tower and a new river training wall was added to divert the river from scouring out the harbour, giving shelter to the anchored boats in times of sea storms and river floods. Source
  • Many roads had been damaged during the flood. A number of these had to be completely re-made including road foundations, embankments and surfacing. The opportunity was taken to modernise, allowing for the requirements of modern traffic. Source
  • The new channels in Lynmouth were designed and constructed to accommodate flood discharges of 425 cubic metres per second for the East Lyn and 255 cubic metres per second for the West Lyn, and a total of 650 cubic metres per second for the River Lyn below the confluence. Source
  • Special treatment was given to the Manor Grounds bank, where a two stage channel was created for the combined rivers. The bed was stepped on two levels to avoid the appearance of an empty channel: the lower 18 metre wide channel conveying the water during dry times of the year and the higher to be available for the higher flow levels on extreme occasions. The 4 metre wide terrace was cobbled on a concrete bed. From here to the river is a 1 in 3.5 slope of reinforced concrete bed, and from the terrace to the Manor Grounds a further 1 in 1 slope, giving a total width of 30.5 metres - a vast increase from the original 10.5 metres. Source
  • The Lyndale bridge was reconstructed to give a clear span of 25 metres, and the new road over the West Lyn had a clear span of 15 metres. These were constructed from pre-stressed concrete beams on mass concrete abutments faced with local stone and of sufficient widths not to be blocked by trees and debris. Source
  • Further upstream, a different design of bridge was used. The alternative to the expensive concrete structures was the relatively cheap, low wooden bridges which are deliberately built to fail in the event of a flood. In such times the wooden structure will simply lift off the stone base and be swept away ensuring that they do not become dammed. Source
 

Videos

 
 
Meteorological Phenomena
Topography
Rescue Effort
Social Consequences
Economic Consequences
Environmental Consequences
Redevelopment
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