Commemorating the great Tay flood of 1814

Published On Tue 11 Feb 2014 by Roddy Isles

Many residents of Perth will still remember the disastrous flooding of January 1993, which left many hundreds of families with flooded homes and memories which they would rather forget. But this week sees the bicentenary of a flood which was recorded as being half a metre higher.

On February 12th, 1814, an ice-jam flood occurred as ice floes gradually blocked the arches of Smeaton's Bridge and constricted the flow. The peak water level marked on the bridge is 7.0 m above sea level, compared with 6.48 m for the 1993 peak[i].

Dr Andrew Black, Senior Lecturer in Geography at the University of Dundee and an expert in flood management, said, 'The 1814 flood is understood to have resulted from ice forming over the Tay and its tributaries over an extended period, and then being dislodged as the river rose in response to a rise in temperature.

'Some sources indicate the inundation of Perth was probably rapid, and one account indicates that the army was called to fire upon the ice with canon, as a means of clearing the blockage, though without success.

'Ice jam flooding in the Tay - or indeed any Scottish river - might seem difficult to imagine to some today but we have visual evidence of a significant depth of ice across the Tay in January 1918, illustrating the potential for flooding if bridge blockage does occur. And it is only three years ago that the River Ayr at Irvine experienced an ice-jam flood.

'We have recently been presented with new research showing evidence of glacier formation in the Cairngorms as recently as 400 years ago, as part of the Little Ice Age - a period of colder conditions which is generally accepted as lasting from about 1350-1850 AD. That period therefore includes the date of the 1814 flood.

'Neither the 1918 or the Ayr event was associated with flooding as severe as affected Perth in 1814. Quite why the levels got to be so high may be difficult to know exactly, though contemporary research indicates that the flow rates generated by catchment snowmelt and rainfall, and the thickness and strength of the channel ice cover are generally important.

'The possibility of ice jam flooding was recognised in the design of the Perth flood defences, with the design standard being set equal to the height of the 1814 flood, with a further freeboard allowance being provided as a safety precaution.'

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