York Civic Trust Plaques

Flood Heights on the Ouse

Plaque at Tower Gardens

SO, you thought the floods of 2015 were bad? Or, even worse, the ‘great floods’ of 2000? Well, they were. But not as bad as some of the deluges that have inundated York at various points in the city’s history over the last 1,000 years.

Amongst the worst were the floods of 1263, when it is thought that a sudden thaw caused water levels in the Ouse to rise about six inches higher than they did at the height of the 2000 floods - this at a time when there were no sophisticated flood defences. Flood water apparently rampaged down North Street as far as the junction of Bridge Street and Ouse Bridge.

In 1316, York Castle was effectively besieged by rising floodwaters - to the extent that essential earthworks were washed away. Then, in 1564, huge chunks of thawing ice carried by floodwaters smashed away parts of Ouse Bridge.

There were two more severe floods - as bad as those of 1263 - in 1625 and 1689. Again, in both cases, the flood waters rose six inches higher than in the ‘great floods’ of 2000. We don’t know what the cause was - but it’s quite possible it would have been melting ice and snow.

Many of the early severe floods were caused by sudden thaws. And it’s a fairly safe bet they would have been worse than the sudden thaws we get these days. Between 1645 and 1715 Britain found itself in the middle of a ‘Little Ice Age’ because of a period of low solar activity we know today as the ‘Maunder Minimum’. So there would have been a lot of ice and snow to melt...

The flood waters have never risen since to quite the levels seen in 1263, 1625 and 1689. Nevertheless, there was serious flooding in 1947, and several more times in the 20th Century before the 2000 and 2015 floods of more recent memory.

It isn’t always easy to be precise about just how high water levels rose in the past, admits David Fraser, chief executive of York Civic Trust, because measurements have been estimated in various ways at various times.

Today, we measure flood heights in meters, and compare water levels in the Ouse to something called the ‘ordnance datum’. According to the Environment Agency, the normal summer water level in York is set at five metres Above Ordnance Datum (AOD). During a really severe flood, water levels rise to more than 10 metres AOD.

That has happened just 14 times since 1263, by our best estimates: in 1263 itself, then in 1564, 1614, 1625, 1636, 1689, 1732, 1804, 1831, 1982, 1997, 2000, 2012 and 2015. The eagle-eyed among you will notice that five of those 14 most severe flood events of the last 750 years have occurred comparatively recently, in the last 33 years. The only comparable period of repeated severe flooding was in the 1600s.

A plaque attached to a wall in Tower Gardens records the height of some of the worst floods in the city's history.

It is very far from complete, showing the 2000 flood at the top, and making no mention of the worse floods in 1263, 1625 and 1689. It also records the flood heights in feet rather than metres, as is now standard. Yet to look at it is to be reminded that flooding in York is not a recent phenomenon. It is the price the city has paid throughout history for being built on low-lying land at the confluence of two rivers and in the shadow of upland areas such as the Pennines and North York Moors, from which rainfall and melting snow drains..

Our understanding of floods and what causes them - both in the past, and today - is evolving. But it is probably fair to say that climate change, development, and farm manage in upland areas all play a part - along with the city's geography. Expensive flood defences, such as the Foss Barrier and other defences that have been put in the pipeline since 2015, can help to protect the city. But encouraging habitats such as upland bogs and moors, woodlands, wetlands and grasslands - all of which can act as giant sponges - will also surely help. That' s one reason why York's Ings are so important...

Stephen Lewis

For the stories behind more York Civic Trust plaques, visit yorkcivictrust.co.uk/