flooding in york

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Flooding in York 1st November to 11th November 2000.

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Page 1: Flooding in York

Flooding in York 1st November to 11th November 2000.

Page 2: Flooding in York

The Flood event which occurred in November 2000 had a return period estimated to be 1 in 80 to 90 years.

In November 2000 York suffered its worst floods since records began some time in the 17th century. The water was over six metres higher than it should have been and came within five centimetres of breaching York's flood defences.

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King’s Arms

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Environmental Agency

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Streets in Clementhorpe

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The purple line shows all flood defences built in the last five years to protect against river floods with a 1% (1 in 100) chance of happening each year, or floods from the sea with a 0.5% (1 in 200) chance of happening each year, together with some, but not all, older defences and defences which protect against smaller floods. Flood defences that are not yet shown, and the areas that benefit from them, will be gradually added.   Hatched areas benefit from the flood defences shown, in the event of a river flood with a 1% (1 in 100) chance of happening each year, or a flood from the sea with a 0.5% (1 in 200) chance of happening each year. If the defences were not there, these areas would be flooded.Flood defences do not completely remove the chance of flooding, however, and can be overtopped or fail in extreme weather conditions. 

Page 14: Flooding in York

Photographs of the historic walled city of York, where the river reached a peak of 17ft 8ins (5.3m) above normal at 0330 GMT on Saturday 4th November 2000, within two inches of breaching flood defences

Page 15: Flooding in York

Lendal Bridge Flood Defences

Page 16: Flooding in York

Foss Barrier

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Catchment area: Rivers Ouse & Foss Right: This map shows the Ouse catchment area upstream of York – a total of 3,000 square kilometres. The River Ouse is fed mainly by the rivers Swale, Nidd and Ure which carry water from the Dales and the Pennines. When there is heavy rain or melting snow on the high ground, the level of the Ouse in York can rise dramatically.

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Clifton Ings

This is a natural flood plain upstream of York which can store 2.3 million cubic metres of water, lowering the peak flood level in the city by 150mm. In 1982, at a cost of £1.25 million, the existing floodbanks were raised and new embankments constructed to provide this greater storage. Sluice controls for letting flood water in and out of the Ings were also put into operation. This system is extremely effective for medium order floods of up to 14 feet (4.27 metres) above normal. For higher order flooding, the site is designed to let the banks overtop, allowing the full capacity of the Ings to be utilised in such an event.

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View of Clifton Ings filledwith flood waterduring the 1995event lookingdownstream of theOuse towards thecity. Utilising thesewashlands canreduce the effectsof high water levelsin the river. Floodwater is returnedto the Ouse whenthe river has fallento a safe level.

Page 21: Flooding in York

Leeman Road

The Leeman Road area of York consists primarily of 19th Century ex-railway workers' houses. It was extremely prone to flooding both from the River Ouse and the adjacent Holgate Beck. In 1978, 225 houses were seriously flooded. In 1980 a floodbank was constructed in front of the houses to protect them from flood water. The sewage system was also improved drastically, allowing sewage to be pumped when the river levels were high. During the 1982 flood, high winds blowing over Clifton Ings generated large waves which overtopped the Leeman Road defences. The floodbank was raised in response to this effect.

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Lower Ebor Street This area of 19th Century housing was badly flooded in 1978. Work had already begun to protect the area when it flooded again in 1982. Since then, a combination of concrete flood walls with steel trench sheeting have

beenconstructed, as well as earthen embankments.

Valves have been installed to isolate the sewage system incorporating a small pump to evacuate sewage when river levels are too

high

Page 23: Flooding in York

Holgate Beck

In order to prevent flooding in the Acomb area of the city, and near the racecourse, upstream tributaries of Holgate Beck were diverted to discharge flow directly into the

Ouse downstream of York. Upstream of York, where Holgate Beck joins the Ouse, a two-pump station was built to control water levels.

Page 24: Flooding in York

The Foss Barrier

The River Foss is a large tributary which flows through York, joining the River Ouse just

downstream from York Castle. Because of the delicate relationship between these two

rivers, rising water in the Ouse can often result in a dangerous reaction in the Foss. A rapid

increase in the volume of water in the Ouse would force the Foss back on itself, causing it to

overtop its banks and flood surrounding properties. It was this dramatic effect that contributed to the severity of the floods in 1947, 1978, and 1982. A solution for the Foss had to be found.

Page 25: Flooding in York