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The Cumbrian Floods In Perspective

December 7, 2015

By Paul Homewood 

  

 

*

Main Street, Cockermouth

 

 

As the floods in Cumbria begin to recede, it’s time for a round up of the facts, and a bit of historical perspective.

 

 

Record Rainfall? 

We have heard of claims that 24-hour rainfall totals at Honister Pass have broken the UK record, with 341mm. This is what DEFRA have to say:

Over the past 48 hours, Environment Agency rain gauges have recorded widespread totals of more than 200mm across Cumbria. Provisional figures from a rain gauge in Honister in Cumbria show that 341mm rain fell in 24 hours (18:30 Friday- 18.30 Saturday). If verified, this will be a UK record for 24 hours. This is more than a month’s worth of rainfall in a day.

 

The gauge belongs to the Environment Agency, and I have asked them to confirm how long it has been operational. As I reported earlier, it only appears to have been operational since 1970, and records since then are incomplete.

I am still not aware of any confirmation from the Met Office.

It is worth noting however that this record only applies to any 24-hour period, and not for a rainfall day, which runs from 9.00am. The record for the latter still remains at Martinstown, Dorset, in 1955, when 279mm fell.

Many more stations are now automatic and give hourly recordings than was the case in the past. Consequently we are statistically much more likely to find 24-hour records nowadays.

If found to be valid, the Honister record will replace the one of 316mm set at Seathwaite, just a mile down the road, in 2009. As Honister lies at an altitude about 700 feet higher, this extra rainfall would not be unexpected.

 

 

Recent Weather in Cumbria

One of the big contributory factors to this week’s flooding in Cumbria has been the large amount of rainfall that accumulated over the region during November. Consequently, the rivers and flood storage reservoirs were already pretty much full even before Storm Desmond hit.

The cause of this weather has been the track of the jet stream, which brought depressions one by one over the North West, rather than elsewhere.

 

2015_11_Rainfall_Anomaly_1981-2010

http://www.metoffice.gov.uk/climate/uk/summaries/anomacts

 

 

Historical Perspective

According to the Lake District National Park, Seathwaite is the wettest inhabited place in England, experiencing around 3500mm of precipitation each year. (The average for the UK as a whole is 1154mm).

The reason is simple. The mountains of the lake district rise up sharply from the sea to the west, only 20 miles away. Any depressions coming from that direction are immediately impacted.

As the map below indicates, Cockermouth is in a particularly vulnerable position, lying at the confluence of the Rivers Derwent and Cocker.

 

image

 

The Environment Agency highlights the problems faced by Cockermouth, and lists some of the flooding events that have affected the town in the past.

Note well the clustering, particularly in the 1930’s.

 

 image

 

 

The Lake District Flood of 1898

There is an interesting paper, published in 2003, “Estimating areal rainfall during the 1898 flood in the English Lake District and the implications for probable maximum precipitation”, by Colin Clark.

The paper gives some of the contemporary accounts of what was a significant flooding event, but there are some interesting snippets of information, of relevance to the current flood.

 

image

 

These are actual rain gauge data.

The figures for the lowland sites of Ambleside and Grasmere in 1898 are remarkably similar to Keswick, supposed by the Met Office to be the worst of the lowland ones this time. (Shap is about 800 feet up).

 

image

http://blog.metoffice.gov.uk/2015/12/06/wind-and-rain-records-for-storm-desmond/

 

 

This gives good reason to suggest that the 1898 storm was every bit as bad.

As the paper makes clear, there were no rain gauges up in the mountains in those days, but, using data from lake levels etc, the paper estimates:

 

Estimation of areal rainfall, especially in mountainous areas, is difficult. The use of lake levels and soil hydraulic conductivity data has enabled an estimate of 260- 280mm over a 24- hour period to be made for the 1898 storm in the Lake Windermere catchment area. This result is more robust and reliable than any estimate obtained from raingauges which are often, as in this case, located in the valleys. The results presented in this paper are based on a historical flood record

 

This of course is an average for the whole catchment area, so it is inevitable that some places would be above the 280mm figure. The paper reports on other studies which arrive at higher figures for the rainfall:

 

The Flood Studies Report (FSR) (Natural Environment Research Council 1975) and Flood Estimation Handbook (FEH) (Institute of Hydrology 1999) both suggest a 24-hour PMP of 300-350mm for the Lake District, with the higher value occurring on the Borrowdale Fells to the north of the Windermere catchment. The FSR/FEH PMP value for an area of 187km2, as distinct from the point values given above, is 280-327mm.

Borrowdale, incidentally, is the valley leading up to Honister Pass.

If any of these figures are anywhere near right, it is clear that there was nothing unprecedented about Storm Desmond, as far as the lake District is concerned.

 

 

Watkins & Whyte

image

http://www.mangeogsoc.org.uk/pdfs/watkins_whyte.pdf

 

There is one more study I want to have a quick look at, by Watkins & White, which was published in 2008.

Note again the reference to “concentrations”. They include the following chart:

 

image

 

And comment:

 

This study has demonstrated the value of historical sources in supplementing data derived from scientific techniques such as lichenometry and radiocarbon dating. For Cumbria it was possible to identify 34 extreme floods which affected upland catchments since AD1600. The evidence supports the information derived from geomorphological approaches indicating that there have been marked changes in the frequency of such floods in the last 400 years, but that the frequency of such floods in the last three decades is not unusual and has fallen markedly from the mid-twentieth century. The occurrence of extreme flood events in upland areas appears to be linked closely with negative NAO values.

 

 

There was no rain gauge up Honister Pass in the 1960’s or earlier. If there had been

32 Comments leave one →
  1. December 7, 2015 9:05 pm

    “If verified, this will be a UK record for 24 hours.”

    Only IF all other rain gauges were monitored for their maximum 24-hour measurement.

    Prior to automated measurements, I suspect they were read at a pre-determined time every day, which probably/possibly wouldn’t coincide with the 24-hour period of maximum precipitation.

  2. john cooknell permalink
    December 7, 2015 9:09 pm

    Paul,

    My understanding is the flooding situation in Carlisle is not linked to the Cockermouth, Keswick et al, which is on a different catchment to that you describe above.

    The record rainfall at Honister might explain why flood defences were overwhelmed at Keswick, Cockermouth, etc., but as far as I can tell the catchment for Carlisle did not receive “record breaking” rainfall. It was extremely wet but it wasn’t record breaking.

    So the cause of why the flood protection in Carlisle did not prevent floods is still to be determined.

  3. Bloke down the pub permalink
    December 7, 2015 9:21 pm

    Only time will tell if some of the flooding caused by Desmond was made worse by flood protection schemes upstream.

  4. December 7, 2015 10:02 pm

    Paul thank you for this very detailed analysis of a very topical event. Unfortunately for the people of Cumbria if the establishment keep their collective heads in the sand and blame everything on climate change and ultimately our burning of hydrocarbons, then they will never get effective flood protection, if indeed that is actually a possibility for them. Some cool analysis is needed.

  5. Mr GrimNasty permalink
    December 7, 2015 10:39 pm

    It’s always happened, and it always will, there’s dozens of ‘worst in living memory’ examples in old news reports, even affecting the same area as now approx. as per 2 of these:-
    1948 floods worst in living memory…..
    http://www.britishpathe.com/video/berwick-floods-sweep-north-wrecked-homes
    1952 Lynmouth
    http://www.britishpathe.com/video/lynmouth-rises-again
    1954 first time in living memory…..
    http://www.britishpathe.com/video/floods-follow-gale-havoc

  6. December 7, 2015 11:10 pm

    Many floods of the last 10 -15 years have been exasperated by the reduction in land husbandry due to the reduction of small hold farmers tending to ditches and other flood routes. A farm gets sold to some city gent type who loves the view, but doesn’t want to pay for clearing the land of over growth etc. In small numbers its ok, but by today, its starting to become a problem!

  7. December 7, 2015 11:47 pm

    When Carlisle flooded in 2005, the EA described it as a 200 year event.
    Before the new defences (also designed for a 200 year event) were even completed in 2009, they came very close to being overtopped and now in 2015 Carlisle is flooded again.

    http://www.newsandstar.co.uk/flood-agency-boss-warns-it-can-happen-again-any-time-1.364956

    https://environmentagency.blog.gov.uk/2015/01/08/10-years-on-from-the-cumbrian-and-carlisle-floods-of-2005/

  8. December 8, 2015 12:23 am

    Reblogged this on WeatherAction News.

  9. potentilla permalink
    December 8, 2015 4:15 am

    Very good summary. Thanks. However the 24-hour point PMP values quoted seem low if 341mm was recorded in 24 hours at Honister:

    “Flood Estimation Handbook (FEH) (Institute of Hydrology 1999) both suggest a 24-hour PMP of 300-350mm for the Lake District”

    PMP stands for Probable Maximum Precipitation and is the largest rainfall that can be developed by moisture maximization of recorded storms. It is extremely rare world-wide that the estimated PMP for a given location is ever exceeded at a rainfall gauge. If the Honister value of 341 mm is confirmed, it is likely that the Lake District PMP estimates will have to be revised upwards.

  10. sexton16 permalink
    December 8, 2015 8:14 am

    Can you imagine the wailing and the beating of breasts if the EA said they were going to end floods by putting in flood channels like those in Los Angeles

    • jazznick permalink
      December 8, 2015 8:36 am

      Quite so sexton16. But that is what is required – currently the overwhelmed flood barriers are keeping the water IN the flooded areas.

      In all the articles I’m reading this morning there is no mention of the IPCC (because they don’t link extreme weather to CC).
      Slingo is using some very slight caution (but she is persoanlly sure it’s CC).

      Someone needs to stand up and say that this is natural variation and that CO2 does not alter the direction of the jet stream !

  11. December 8, 2015 8:32 am

    Unfortunately, the Big Brother Corp and other meja have already capitalised on this as an AGW bonus. No discussions of historical flooding, drainage reduction, flood plains etc. Its convenient for all to put it on climate change. The Sligo et al were duly interviewed and gave the usual responses, so this is what most of the population are fed.

    Its amazing that there are still so many people who are not convinced by the welter of brainwashing that occurs at every opportunity.

  12. December 8, 2015 1:30 pm

    The “Metro” had an article today, about the waterfall at Malham Cove, which became the highest in England after “being brought back to life” by storm Desmond.
    The article says that: Malham Cove, which has been dry for hundreds of years, was rejuvenated by heavy rainfall over the weekend.
    Also covered by the BBC:
    http://www.bbc.co.uk/news/uk-england-york-north-yorkshire-35024253

    The timing is a bit vague but presumably that means there has been similar rainfall in the past.

    • margie permalink
      February 17, 2016 2:46 pm

      I have to say I recall going to Malham as a child and I am certain that water fell over the rock face when we visited. I also recall seeing occasional thin trickle downs twenty or thirty years ago.

      The fact living memory serves only those aged 30 somethings feeding the BBC reportage, does little to convince me that due diligence has been given to assiduous research.

      Finding folk whose living memory of Malham’s history could be relied upon is getting harder due to so much of the local community being replaced by second home buyers and folk not from the region, sadly.

      The BBC will say anything that grabs a headline for them.

  13. Sydney Ashurst permalink
    December 8, 2015 1:41 pm

    The statistics of rainfall are for the Lakes, i.e. the old County of Cumberland. If these are new records of rainfall concentration, it begs the question how has the claimed AGW/climate change changed the pattern of North Atlantic depressions?
    Flooding in Carlisle is due mainly to the River Eden, which also flooded Appleby. The Eden rises in the Pennines in the old County of Westmoreland. What are the rainfall statistics for this catchment area?

  14. December 8, 2015 11:29 pm

    I have to say I still blame climate change for all this as the frequency of these types of events in Britain has dramatically increased over the last 10 years or so. We’re seeing railways shut on a regular basis which they didn’t used to be, landslides increasing in regularity, flooding more than once a year and much more serious than I’ve ever seen in my (fairly long so far) lifetime. We certainly don’t have anything to lose if we cut our fossil fuel use and our profligate use of energy.
    Carol.

    • December 9, 2015 2:03 pm

      I suspect that you have little evidence for those thing other than the fact that they are reported on more these days, which is a different thing.
      They may have increased from a low base in the 1960’s and 1970’s but to take one example, rainfall in England and Wales was just as high in the second half of the 19th century and the mid 18th century. Was that caused by “climate change”?
      I suspect that if we had as good a record of floods then, as now, there would be just as many.
      That’s apart from the fact that there’s more stuff to flood now than there was then.
      More houses, roads, car parks, paved driveways, all of which exacerbate floods.

      • December 9, 2015 7:52 pm

        Not really – it’s more my experience of things as I travel around almost constantly in my pursuit of hills. There are very many times when I’m seeing that a railway line is closed or a road route which never used to happen on my travels prior to this last 10 years or so. I’ve always travelled around…

        Definitely there is a problem with people paving over their gardens and more of the land going under tarmac/concrete but the severe storms I’m seeing now and the really severe rainfalls didn’t used to happen anywhere I travel to before this last decade or so. Certainly not on such a regular basis.

        So, definitely things have changed a lot in my lifetime and all the major changes seem to have been very recent.

    • December 9, 2015 8:24 pm

      The climate is not constant.
      It would agree that there seems to have been a lot of bad weather recently (particularly wind – but there is no data on that) but changes over over a mere 10 or 20 years or so are not evidence of long term climate change caused but CO2.
      Humans have to find something to blame bad weather on, and don’t seem to be able to accept it’s random and you can get short term trends in random data. First it was God, now it’s CO2. I remember in the 50’s we blamed bad weather on Atomic tests.
      Reducing CO2 won’t prevent storms.

      • December 9, 2015 8:27 pm

        I still think we should play on the safe side though and cut our emissions. We’re just profligate with all resources as a race and it’s time we were a bit more responsible in our actions.

      • December 9, 2015 8:44 pm

        I thought there should be a name for what I am talking about (the belief that recent events, or ones which are reported on more often, are becoming more frequent), but there are so many cognitive biases and I haven’t identified which this is yet.
        https://en.wikipedia.org/wiki/List_of_cognitive_biases
        The “Availability heuristic is the nearest I have found so far.
        Any psychologists out there?

    • December 9, 2015 9:03 pm

      “I still think we should play on the safe side though and cut our emissions.”
      If only it were that simple>
      How do you suggest we do that?
      Cover the country in wind farms?
      Nuclear power plants?
      Remember it isn’t just the UK, it’s the world!

      • December 9, 2015 9:14 pm

        It most definitely is the world – and everyone on it needs to be cutting down their energy usage. I personally don’t have a problem with windfarms but there are a lot of other sources of renewable energy and we’ve only just begun to scratch the surface. We need to actively look into all the possibilities. I was part of a 10 year scientific study into wavepower in the 1970s until the government of the day suddenly cut all the funding and shut it down. We were making progress too. Now all that work has to be started again (I think research into it has already started again fortunately).

  15. December 10, 2015 9:01 am

    Mountaincoward has really swallowed the message, hook, line and sinker. If only we would cut our energy usage, we would stop the heavy rain fall that happens in the UK on a periodic basis. So faith based, it is quite sad, because as long as they can blame something else and tell us that it’s all our fault for enjoying the convenience of modern living, they don’t have to spend money on the real problems which require annual maintenance.

    http://www.cockermouth.org.uk/floodsmaintenancecampaign.pdf

  16. December 10, 2015 9:27 am

    One of the problems that happens with all the reporting on flooding is the concept of a 1 in 100 year event, which people, and I include politicians, take literally. It is considerably more complex than that, as explained here: http://www.livescience.com/5751-100-year-storm.html. It relates to storms in Atlanta GA in 2009.

    “Meteorologists, climatologists and hydrologists calculate 100-year events as a statistical tool to determine the likelihood of intense storms or floods. For example, meteorologists use the average year-to-year rainfall in a given area to figure out the chances of having a storm of potentially epic proportions, explained Pam Knox, Assistant State Climatologist of Georgia.

    “What it means is that every year there’s a 1-in-100 chance of one of these happening,” she told LiveScience.

    So while these events have a lower statistical likelihood of happening than your average thunderstorm, they can and do happen, sometimes within just a few years of each other.

    These 100-year events can be calculated for different rain durations as well, Knox said. An area could have a one-hour “100-year event” or 24-hour one.

    In such monumental deluges, flash flooding typically occurs because the soil quickly becomes saturated and the water has nowhere to go. This flooding can be exacerbated when an area is heavily paved, as Atlanta is, because there is even less ground capable of absorbing the excess water.

    The associated 100-year floodplains are the areas that could be impacted if such a flood strikes. If you live on any floodplain, the chances are about 1-in-2 that you will experience a flood in your lifetime, according to the U.S. Geological Survey (USGS).

    The floods that wreaked havoc in the Midwest in 2007 and 2008 were both 500-year floods, according to one USGS official. Five hundred-year floods (and 50, 25, 10 or whatever interval you want to use) work on the same logic as 100-year events.

    “Essentially, a 500-year flood is just that quantity of water that has the 1-in-500 chance of happening in any one year. Another way to say it would be, there’s a .2 percent chance of a flood of this magnitude occurring in any one year,” said Bob Holmes, the National Flood Coordinator for the USGS, in a USGS podcast.”

    When you have flood victims on TV saying “worst in living memory” that demonstrates that they are not very frequent. Chance means that there will be clusters of years, so someone gets the real impression that in their lifetime, things are happening more frequently. Short term observations are totally unhelpful in assessing climatic trends.

    This link puts it into more perspective, well worth a look. :

    http://water.usgs.gov/edu/100yearflood.html

    “The term “100-year flood” is used in an attempt to simplify the definition of a flood that statistically has a 1-percent chance of occurring in any given year. Likewise, the term “100-year storm” is used to define a rainfall event that statistically has this same 1-percent chance of occurring. In other words, over the course of 1 million years, these events would be expected to occur 10,000 times. But, just because it rained 10 inches in one day last year doesn’t mean it can’t rain 10 inches in one day again this year.”

  17. December 10, 2015 10:43 am

    According to the MO HadUKP (precipitation figures) for the North West and Wales (unfortunately no figures for the NW in isolation) which start in 1873, rainfall for that region for the year to date at the end of November, was 950.5mm.
    Assuming the maximum ever recorded rainfall for December (201.7mm in 1986), the annual figure for 2015 will be about 1153 mm against median figure of 1027mm.
    This will not be a particularly high annual figure (by definition the median is exceeded in 50% of years), the highest being 1375.7mm in 1877.
    Of course, it was not the annual figure which determined the flooding potential for a particular day in December, and it remains to be seen what the actual December figure is.
    However, the location of rainfall within a particular region and on a particular day, is essentially a matter of chance, so I think that the annual figures give a good indication of whether anything unusual is taking place.

  18. dawid permalink
    February 10, 2016 8:15 pm

    savage

  19. margie permalink
    February 17, 2016 2:59 pm

    I read a fascinating article in a NE news in December where the author, a retired farmer turned writer, recalled how he and other land owners would dredge rivers and clean ditches to accommodate heavy rainfall and avert floods. he gave fascinating accounts of the history of dredging and ditch clearing and farming methods used to avert over flooding in the region.

    He blamed the EU for dictating that rivers should not be dredged as this damages the embankment, destroys habitats etc and also alters the natural landscape development . The fact no one in the EU knows the first thing about island living and the UK landmass didn’t deter them giving out some silly directive.

    The EA are happy to give over governance of landscape in Cumbria to so called environmental groups to take care of, as it relieves them of any workload that interferes with their new policy of never mind the environment how about making a fast buck, imposed upon them by the government.

    I have noticed over the years that Coniston and Derwent are highly silted up and reclaimed by landmass at southern ends and wondered how far this factored into lack of basin for high levels of rain in the River Derwent, to feed into quickly? I think orgs such as RSPB and National Trust are happy enough for these new land masses to abutt their operations, as for sure they then claim more land. However, it would seem silly to not dredge the lake basins otherwise in decades to come there wont even be a lake district at this rate of silting up of lake bed.

    I also wonder if a storm surge up River Derwent may have added to the sudden flooding thiis time around, but the convergence with Derwent and Greta near the head of Lake Derwent does need some kind of attention, as if the Derwent continues silting up, Greta will sure take full force of flood flow into Keswick?

  20. margie permalink
    February 17, 2016 3:13 pm

    I would add that the Museum at Ambleside has a brilliant collection of weather books for anyone to pursue. I have spent many and our there trawling through old accounts, written in proper English not the ridiculous stuff now used to jargonise weather, and delivers a brilliant encounter with historical weather patterns devoid of propaganda and spin.

    However, for a tour of Brit weather historically the Anglo Saxon Chronicles are a good guide, as well as this excellent website which takes extracts from it of historical extremes going back millennia…worth a read

    http://booty.org.uk/booty.weather/climate/1650_1699.htm

    Enjoy the tour

    • James Hay permalink
      September 2, 2016 9:48 am

      I read with interest Paul Homewood’s article and “margie’s” comments regarding rainfall/flooding and the silting up of Coniston and Derwentwater. I am a third year BSc Geography student at the University of Leeds presently starting work on my final years dissertation in which I am going to research Flooding and what effect sedimentary deposits after flooding have on lakes and surrounding areas and I am going to focus on the Lake District. Does anybody know where I can find any records that would perhaps show any changes to surface area of lakes/depth of lakes due to silting over the years? Does anybody know of any papers/records that refer to core sediment samples taken from lakes/lake shores in the Lake District. I would appreciate any reply that could point me in the right direction.

      • mar g permalink
        September 4, 2016 8:51 am

        Hi James, The records you need may be held by the EA, but searching the labyrinthine archives on the net on the gov site takes a millions years. I would phone the EA in Cumbria and hope you get someone who is capable and amenable to pointing you in the correct direction to records of silt examination.
        You could also try the dept for environment at the Cumbrian council or phone United Utilities which is the water company dealing with testing water, but not necessarily around lakes/rivers that are not part of the drinking water basin in Cumbria.
        There’s a lot of fudging around who collects and keeps which data due to the EU regs which changed the way these were accounted for and collected over the past 40 or so years.
        A search for ”Environment agency Cumbria” or even ”History of water levels Cumbria district” will yield many pages, and you may be lucky and get a result of someone with a personal website with interest in the subject, who will be more factual and diligent than the spin and PR that comes out of the EA et al.
        However a search for ”core sediment samples Cumbrian lakes” yields more academic site results which may best serve your purpose as well as helping connect you to academics who would be useful contacts for your research.

        My advice would be to check out the funding behind any site or academic paper to ensure you are not lead into more spin and indoctrination the benefactor is trying to perpetuate via academia.

        Good Luck.

  21. James Hay permalink
    September 29, 2016 9:50 pm

    Thank you very much for your help.

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