BOXING DAY FLOODING 2015

The North of England experienced exceptional levels of rainfall during November and December

2015. Parts of North West England and South West Scotland had 200% of the average rainfall in

November (the UK overall figure was 113% of the average) and December was the second wettest on

record according to the Met Office, with a number of locations having record breaking levels of rain

Map of December 2015 rainfall showing variation from average

Source: The Met Office

Storm Eva hit the UK on Christmas Eve bringing high winds and heavy rain to large areas of the

Northern UK, further saturating the ground. This was quickly followed by a further Atlantic low

pressure system (not a named storm) and it was this system which brought the very heavy rain on

Christmas Day and Boxing Day.

Position of low pressure system 26.12.15

Source: Met Office

Storm Eva

Atlantic Low

Pressure

System

The Met Office issued seven severe flood warnings (meaning danger to property and life) for

Lancashire and 24 severe flood warning for Yorkshire.

The reason for the intensity of the rainfall was very similar to Storm Desmond earlier in December.

The low pressure system dragged warmer, moister air from the sub-tropical Atlantic region. A

combination of frontal systems (high pressure over Europe) and UK mountain terrain forced this air

upwards leading to condensation and heavy and sustained rainfall.

The chart below shows precipitable water in the atmosphere (the amount of water vapour that is

available to be converted in to rain). This shows the UK again at the end of an “atmospheric river” of

moist air being driven North East from the sub-tropics.

Precipitable Water Chart as at 24.12.15

Source: www.netweather.tv

RAINFALL

Rainfall of up to 120mm (5 inches) fell in the 24 hours period around 26th December in the Lancashire and Yorkshire areas. To put this into context, average rainfall for December for the entire month is 145mm.

RIVERS

The intense rainfall in a short period of time on already saturated ground led to rapid run off into the

river system and a number of rivers exceeded their previous highest ever levels.

Major Rivers Affected in Boxing Day 2015 Flooding

Area River Peak Height “Average” peak Previous record

% previous record

Leeds Aire 5.2m 2.12m 4.03m 129%

Rochdale Roch 2.4m 1.3m 2m 121%

Sowerby Bridge Calder 3.6m 1.4m 2.4m 146%

York Ouse 5.2m 1.9m 5.4m 96%

Manchester Irwell 5.2m 1.1m 4.34m 120%

Source: www.riverlevels.co.uk

The main areas affected in Yorkshire were along the Calder, Aire and Ouse Rivers shown on the map

below:

Major Yorkshire Rivers

The River Calder in particular caused extensive damage along the upper Calder Valley, from

Todmorden to Brighouse:

Upper Calder Valley area shown in more detail below

Upper Calder Valley Area

Source: google maps

In Lancashire, the rivers causing most damage were the Irwell and Roch, shown on the map

below:

River Irwell Catchment Area

Source: Environment Agency, Irwell Catchment Flood Management Plan

The record river levels have led to widespread and serious flooding with hundreds of flood

alerts issued across the North and at one point over 30 severe flood warnings.

The Met Office issued two separate Red Alerts, the first time in its history that two such

alerts have been issued on the same day.

Whilst many of the areas had been affected by flooding in the past, the immediate reaction

was that this event was the worst in living memory. Many areas already had some form of

flood defence in place and others were in the process of improving existing defences.

Unfortunately the defences were unable to cope with the record river levels and in many

instances were overtopped.

Some of the main locations affected are summarised below (farthest upstream first) and in

the following pages more detailed information is provided on the river heights and

circumstances for individual towns and villages, including comment on flood defences where

information is currently available.

River Calder (West Yorkshire)

Hebden Bridge Mytholmroyd Sowerby Bridge Elland Brighouse River Aire (West Yorkshire)

Silsden Keighley Bingley Shipley Leeds River Ouse/ Foss (North Yorkshire) York

River Irwell (Lancashire) Bury River Roch (Lancashire) Rochdale River Calder (Lancashire) Whalley

Hebden Bridge (Postcodes:HX7)

River Calder

River Calder height data

Source: www.riverlevels.co.uk

Following the intense rainfall, the River Calder reached record levels on Boxing Day. The river rose in

height quickly from 0.2m on Christmas Day to over 3.6m 24 hours later.

The River Calder is a known flood risk and following previous incidents various flood defence works

were in progress at Hebden Bridge and further upstream in Todmorden. Given the exceptional level

of rainfall and the rapid rise in the river to record levels, these were unable to prevent extensive

flooding to homes and businesses in Hebden Bridge.

Flooding in Hebden Bridge

The normal level of the Calder at Hebden Bridge in average weather conditions is between 0.02m and 0.75m.

The usual range in more extreme weather conditions is between 0.02m and 1.42m. It has been between these levels for 90% of the time since monitoring began.

On 26/12/15 the river reached its highest ever recorded level at 3.63m. The previous record was 3.33 in 2012.

Key: Low, average & high levels Typical High level Typical Low level

Mytholmroyd (Postcodes: HX7)

River Calder

River Calder height data

Source: www.riverlevels.co.uk

Following the intense rainfall, the River Calder reached record levels on Boxing Day. The river rose in

height quickly from 1.1m on Christmas Day to its highest ever level of 5.65m 24 hours later.

The flood alert siren was sounded at 7am and the river level continued to rise very quickly, reaching

head height in some areas. Mytholmroyd also suffered severe flooding in 2012. A recent

Environment Agency report concluded that dredging the river would not be effective in mitigating

flood risk but did focus on removal of vegetation. Physical flood defences were not implemented in

Mytholmroyd as investment was directed towards Todmorden and Hebden Bridge, further upstream.

Flooding in Mytholmroyd

Source: ITV News

The usual of the Calder at Mytholmroyd is between 0.43m and 2.10m.

It has been between these levels for 90% of the time since monitoring began.

On 26/12/15 the river reached its highest ever recorded level at 5.65m. The previous record was 4.85m in 2012.

Key: Low, average & high levels Typical Low level

Sowerby Bridge (Postcodes: HX6)

River Calder

River Calder height data

Source: www.riverlevels.co.uk

Following the intense rainfall, the River Calder reached record levels on Boxing Day. The river rose in

height quickly from 0.16m on Christmas Day to over 3.5m only 24 hours later.

The River Calder is a known flood risk however Sowerby Bridge has not suffered such a severe

incident since 1968.

Flooding in Sowerby Bridge

Source: Yorkshire Post

The normal level of the Calder at Sowerby Bridge in average weather conditions is between 0.00m and 1.31m.

The usual range in more extreme weather conditions is between 0.00m and 1.40m. It has been between these levels for 90% of the time since monitoring began.

On 26/12/15 the river reached its highest ever recorded level at 3.55m. The previous record was 2.43 in 2012.

Key: Low, average & high levels Typical High level Typical Low level

Elland (Postcodes: HX5)

River Calder

River Calder height data

Source: www.riverlevels.co.uk

Following the intense rainfall, the River Calder reached record levels on Boxing Day. The river

quadrupled in height from 0.67m on Christmas Day to over 2.75m only 24 hours later. The highest

ever recorded level was reached with river levels to this extent not seen since 1967.

Elland Bridge partially collapsed during the flood and was struck by a barge (below). The bridge has

now been confirmed as beyond repair, with serious implications access to the town for the whole of

2016 as diversion routes are likely to be lengthy.

Damage to Elland Bridge

Source: Huddersfield Examiner/ ITV

The normal level of the Calder at Elland in average weather conditions is between 0.32m and 0.94m.

The usual range in more extreme weather conditions is between 0.35m and 1.49m. It has been between these levels for 90% of the time since monitoring began.

On 26/12/15 the river reached its highest ever recorded level at 2.75m. The previous record was 2.49 in 1967.

Key: Low, average & high levels Typical High level Typical Low level

Brighouse (Postcodes: HD6)

River Calder

River Calder height data

Source: www.riverlevels.co.uk

The River Calder has a history of flooding in the upper and middle Calder valleys and defences are on

average built to withstand floods with anticipated frequency of 1 in 25 to 1 in 75 year frequency. The

intense rainfall over Christmas and Boxing Days led to the highest ever level recorded for the River

Calder at Brighouse, rising rapidly from 22cm on Christmas Day to over 2m on Boxing Day. Defences

were overtopped leading to widespread flooding in the centre of Brighouse.

Flooding in Brighouse

The normal level of the Calder at Brighouse in average weather conditions is between 0.0m and 0.58m.

The usual range in more extreme weather conditions is between 0.0m and 0.80m. It has been between these levels for 90% of the time since monitoring began.

On 26/12/15 the river reached its highest ever recorded level at 2.05m. The previous record was 1.95m in 2006.

Key: Low, average & high levels Typical High level Typical Low level

Silsden (Postcodes: BD20)

Silsden Beck(Tributary of the River Aire)

Silsden Beck height data

Source: www.riverlevels.co.uk

Silsden Beck overflowed on Boxing Day, leading to flooding of nearby properties and the subsidence

of part St John’s Street and a section of wall at risk of collapse.

The Beck has a history of flooding and attempts at improving flood defences have been somewhat

controversial with local residents and Bradford Council regarding design and planning permission. At

the time of the flood the barrier was not completed.

Silsden, including incomplete defence work (left)

The normal level of Silsden Beck in average weather conditions is between 0.02m and 0.03m.

On 26/12/15 the Beck reached 0.45m, close to its previous record level of 0.47m in 2000.

Key: Low, average & high levels Typical High level Typical Low level

Keighley (Postcodes: BD21)

River Worth (Tributary of the River Aire)

River Worth height data

Source: www.riverlevels.co.uk

The River Worth runs to the South of Keighley town centre and a number of industrial sites line its

route. It joins the larger River Aire in Stockbridge to the North East of the town. Parts of the town

were flooded in 2000 and millions of pounds were subsequently spent on flood defences. The record

equalling river levels overcame these defences

Flooding in Keighley

Source; Keighley Times/ Paul Cook

The normal level of the Worth at Keighley in average weather conditions is between 0.23m and 0.68m.

The usual range in more extreme weather conditions is between 0.22m and 1.00m. It has been between these levels for 90% of the time since monitoring began.

On 26/12/15 the river equalled its highest ever recorded level at 2.15m.

Key: Low, average & high levels Typical High level Typical Low level

Bingley (Postcodes:BD16)

River Aire

River Aire height data

Source: www.riverlevels.co.uk

The torrential rain on Christmas and Boxing Day led to a rapid rise in the level of the River Aire which

burst its banks on the evening of Boxing Day. It rose quickly from a level of 0.44m on Christmas Day

to a record 3m on Boxing Day – more than double the previous record height. It remained at record

levels for over 24 hours

Flooding in Bingley

The usual range for the Aire at Bingley is between 0.23m and 1.30m. It has been between these levels for 90% of the time since monitoring began.

On 27/12/15 the river reached its highest ever recorded level at 3.02m. The previous record was 1.42m in 2008.

Key: Low, average & high levels Typical High level Typical Low level

Shipley (Postcodes:BD17; BD18)

River Aire

River Aire height data

Source: www.riverlevels.co.uk

The torrential rain on Christmas and Boxing Day led to a rapid rise in the level of the River Aire which

burst its banks on the evening of Boxing Day. It quadrupled in height from of 0.67m on Christmas Day

to a record 2.8m on Boxing Day – over a meter higher than the previous record height. It remained at

record levels for over 24 hours.

Significant flooding occurred through Shipley, centred on the Baildon Bridge area and the picture

below indicates the force of the river as shipping containers are picked up and carried along, striking

the bridge.

Flooding in Shipley (Baildon Bridge area)

The usual range for the Aire at Shipley is between 0.35m and 1.10m.

It has been between these levels for 90% of the time since monitoring began.

On 26/12/15 the river reached its highest ever recorded level at 2.81m. The previous record was 1.66m in 2008.

Key: Low, average & high levels Typical High level Typical Low level

Leeds (Postcodes:LS1; LS3; LS4)

River Aire

River Aire height data

Source: www.riverlevels.co.uk

Following the intense rainfall, the River Aire reached record levels on Boxing Day and continued to

rise slightly on the 27th December. The river burst its banks and the flooding affected an estimated

2000 homes and 400 businesses. The Kirkstall and Stourton areas (East and West of the city centre

respectively) were particularly badly affected and contain a high concentration of industrial units.

Proposals for a £190m flood defence scheme were rejected by the government in 2011 on cost

grounds. Defences to protect the City Centre are being upgraded at a cost of £45m but will not be

ready until 2017

Flooding in Leeds

The normal level of the Aire at Crown Point in average weather conditions is between 0.40m and 1.05m.

The usual range in more extreme weather conditions is between 0.53m and 1.35m. It has been between these levels for 90% of the time since monitoring began.

On 27/12/15 the river reached its highest ever recorded level at 2.95m. The previous record was 2.45 in 2007.

Key: Low, average & high levels Typical High level Typical Low level

York (Postcodes:YO1; YO10, YO19; YO23; YO26; YO30; YO90; YO91) River Ouse

River Ouse height data

Source: www.riverlevels.co.uk

River Foss

River Foss height data

The normal level of the Ouse at Viking Recorder in average weather conditions is between 0.07m and 1.17m.

The usual range in more extreme weather conditions is between 0.05m and 1.9m. It has been between these levels for 90% of the time since monitoring began.

On 27/12/15 the river reached 5.14m. The highest ever level is 5.4m in 2000.

Key: Low, average & high levels Typical High level Typical Low level

The normal level of the Foss at Foss Barrier in average weather conditions is between 5.07m and 6.13m.

The usual range in more extreme weather conditions is between 5.05m and 7.9m. It has been between these levels for 90% of the time since monitoring began.

On 26/12/15 the river reached 9.095m at 21:00. The highest ever level is 10.2m in 2000.

Key: Low, average & high levels Typical High level Typical Low level

The Rivers Ouse and Foss meet in the centre of York and have a long history of flooding. In previous

flood incidents the Ouse (by far the larger river) has forced water back up the Foss, leading to

extensive flooding. Following record flooding in 1982, the Foss Barrier was built in 1987.

The 16.5-ton barrier can be lifted in and out of position to separate the two rivers and isolate the

Foss from the Ouse at times of flood. Eight pumps divert 30 tons of water per second around the

barrier to ensure a continuing flow from the Foss into the Ouse and keep river levels under control.

In 2000 – when 500 properties were flooded and the River Ouse reached the highest ever recorded

level in York – the Foss Barrier was able protect properties that flooded on 27/12/15.

On this occasion flood water from the Ouse entered the barrier building housing the pumps,

affecting electrical equipment. The authorities were concerned that if they lost power the barrier

would be locked in the down position with the pumps inoperative, leading to more severe flooding

than with the barrier raised. The decision was therefore taken to raise the barrier at 9pm on 27th

December.

The Environment Agency issued the following statement on 27/12/15

The immediate impact of the barrier being raised at 9pm can be seen from the river level graph in

the data above but shown in more detail below:

Impact of Foss Barrier Raising

Source: Environment Agency

These high levels caused water to enter the Foss Barrier Building. The pumps within the building are in danger of failing. The decision has been taken to lift the Foss Barrier gate, as if it fails in the down position water would be unable to discharge into the River Ouse. The Foss Barrier is now open.

The immediate area at risk is the city centre and areas of Huntington, Tang Hall, Osbaldwick and Foss Islands. People in these areas should start to move valuables to upper floors and be prepared to be evacuated.

The Environment Agency have confirmed that if the barrier had been stuck in the closed position

then flooding would have been more serious, with c 1800 homes at risk.

Foss Barrier in closed position

Aerial View of York Flooding

Flooding Cumberland Street, York

Bury (Postcodes: BL8; BL9)

River Irwell

River Irwell height data

Source: www.riverlevels.co.uk

The River Irwell reached its highest ever level in Bury during the torrential rain of Christmas and

Boxing Day. The rapid increase in river levels shown above caused widespread flooding and also loss

of power to around 680 properties in Bury. The League One match between Bury FC and Blackpool

was postponed.

Flooding in Bury

The normal level of the Irwell at Bury in average weather conditions is between 0.23m and 0.71m.

The usual range in more extreme weather conditions is between 0.23m and 1.30m. It has been between these levels for 90% of the time since monitoring began.

On 26/12/15 the river reached its highest ever recorded level at 2.13m. The previous record was 1.76m in 2012.

Key: Low, average & high levels Typical High level Typical Low level

Rochdale (Postcodes:OL11)

River Roch

River Roch height data

Source: www.riverlevels.co.uk

With over 34mm of rain falling in 12 hours on Boxing Day, the River Roch burst its banks leading to

flooding up to 4 feet deep in parts of the town centre.

The Environment Agency has advised that ongoing work to open up the river prevented more severe

flooding as the flood water was able to dissipate more rapidly. Rochdale Metropolitan Borough

Council has a detailed strategic flood plan for 2014-2024 which can be viewed on their website.

Flooding to an electricity sub-station also caused power cuts to around 20,000 households and

businesses in the Rochdale area.

Flooding in central Rochdale

The normal level of the Roch at Albert Royd Bridge in average weather conditions is between 0.30m and 1.33m.

The usual range in more extreme weather conditions is between 0.26m and 1.3m. It has been between these levels for 90% of the time since monitoring began.

On 26/12/15 the river reached its highest ever recorded level at 2.43m. The previous record was 2.01 in 2008

Key: Low, average & high levels Typical High level Typical Low level

Whalley (Postcode:BB6)

River Calder(Lancashire)

River Calder height data

Source: www.riverlevels.co.uk

The River Calder in Lancashire is separate to the Calder in West Yorkshire and is a major tributary of

the River Ribble.

The torrential rain of Christmas and Boxing Day led to a rapid rise in the level of the Rover Calder,

which rose by nearly 4m in just 24 hours. The river reached its highest ever level, exceeding the

previous record by half a metre and flooded the main street in Whalley.

Whalley is an area of moderate flood risk and defences are in place for a 1 in 40 year frequency

event. The river level far exceeded this and the defences were unable to protect Whalley from

serious flooding on this occasion.

Flooding in Whalley

The usual range for the Calder at Whalley is between 0.31m and 1.38m in average conditions

The range in more extreme conditions is between 0.33m and 2.20m. It has been between these levels for 90% of the time since monitoring began.

On 26/12/15 the river reached its highest ever recorded level at 4.64. The previous record was 4.12m in 2012.

Key: Low, average & high levels Typical High level Typical Low level