Storm Surge 2013 : One Year On - Part Four : Spurn

by @cloudskinner

This is the fourth and final installment of our mini-series looking back over the year since the 5 December 2013 storm surge, which flooded many areas in the Humber Estuary and along the east coast of the UK. The first part, Modelling the Surge, looked at the research that has been conducted since the storm surge and has advanced our knowledge and understanding of these events in the Humber. Part Two, What we Learnt, focused on the 2014 Humber Conference and the lessons that have been learnt over the year. Last week guest blogger, Jazmin Scarlett, told us about some of the often unseen impacts of flooding, the mental health issues that can arise, and how communities band together after disasters.

For the final part I want to take a longer look into the future and try and predict what it has in store for Spurn. Spurn, or Spurn Point as it is commonly known, is a piece of land that resembles a spit, sweeping out from the edge of the Holderness Coast and round into the estuary. It is important for several reasons: it hosts the signalling station for the Association of British Ports (ABP), kind of an air traffic control but for shipping; it is home to lifeboat crews (formerly permanently, with their families, but now just the crews whilst on shift), providing them quick and easy access to the North Sea and the estuary; it is an important site for migrating bird life, being a National Nature Reserve owned by Yorkshire Wildlife Trust; it keeps the mouth of the estuary narrow – it is not known what effect a wider mouth would have but it is expected that it could lead to a narrower channel with implications for shipping; and finally, it acts to guard the estuary from the full ravages of storms and waves.

When evaluating the true impact of the 5 December 2013 storm surge one cannot ignore Spurn. One of the most dramatic scenes from that night was the damage done to the landform, as highlighted in the LiDAR images below.

The breach at Spurn as shown by LiDAR data. Light Detection and Ranging (LiDAR) techniques uses rapid pulses of laser light to measure the elevation of the ground, both rapidly and in high detail. The top image shows the breached section of Spurn before 2013, and bottom image shows the same section measured shortly after the 5 December 2013 event 

(LiDAR data collected and provided by the Environment Agency).

It is clear that extensive damage was done by the waves and high water levels during the storm surge. The water will have over topped the narrow spit of land that separates the sea from the estuary, and washed the embankment down towards the estuary – you can see in the image that the bank has gone, and a mound of material has built to the left, on the estuary side.

There once was a road here at the breach site 

(author's own photo taken November 2014)

To understand the implications of this, and what the future might be, we need to delve into the past of Spurn. There are two theories behind the formation of Spurn which have emerged from two former University of Hull academics -

1. George de Boer long maintained that Spurn was a spit – material eroded from the Holderness Coast washes down via longshore drift, and is deposited as a long spit in the form of Spurn. Over time as the coast line retreats, this spit will be rapidly destroyed and another will form further back in line with the coast.
2. John Pethick disagreed however – He argued that Spurn was not a spit as such and had not retreated over time through repeated cycles of destruction. Rather, the end of Spurn is an island and had been in a fixed position throughout history, whilst the area between the island and coast is in a constant state of flux, sometimes forming a spit, sometimes a chain of islands and sometime open channel and sand banks. Although the location of this region has shifted over time with the coast, the end of Spurn has remained.

Until the 2013 storm surge both these theories were just academic. In his chapter of Neale and Flenley’s 1981 book, ‘The Quaternary in Britain’, de Boer recounts the recent history of Spurn and tells a tale of how it became a very man-made feature. He claimed that a cycle of destruction was taking hold in 1849, initiated by a violent storm (probably not unlike 5 December), and within a few years several wide and deep breaches formed along the narrow spit as it were then.

Water at high tide washing over the breached section of Spurn 

(author's own photo taken in November 2014)

In response, and to maintain the lighthouse and lifeboat crews housed there, the government at the time funded works to fill the breaches and huge loads of chalk from Barton-upon-Humber were dumped into the channels to fill them. Spurn came into the hands of the military and prior to WW1 the defences were bolstered and groynes put in place to let the spit grow. During both World Wars Spurn played an important role, not least in monitoring for possible enemy U-Boats infiltrating the estuary. It even had a railway line until 1951, and withstood the infamous 1953 storm surge with little damage.

In the 1960’s Spurn passed from military hands into the Yorkshire Naturalist’s Trust and eventually Yorkshire Wildlife Trust’s ownership, and the focus shifted from maintaining the hard, man-made structures of Spurn to the conservation of its environment and wildlife – as such the investment and work done to retain the defences has significantly decreased. I am sure George de Boer, if he were alive today, would suggest that the breach is the beginning of the cyclic destruction of Spurn that was stalled in the 1840’s.

View across the full breached section 

(author's own photo taken in November 2014)

I’m more inclined to side with John Pethick, however. Even if we were to just let nature take its course, I cannot envisage Spurn being utterly destroyed and replaced further into the estuary, nor do I think the evidence is strong for that having happened in the past, but it is clear that without huge investment to rebuild the spit as it were before 5 December, the nature of Spurn is going to change and will be in flux.

To predict what will happen to Spurn in the future, as the Holderness Coast retreats further back and sea levels rise, we need to adapt our models to be able to simulate some of these scenarios. Equally, it is important that we turn again the research of George de Boer and John Pethick, dig even further and try to understand the nature of Spurn; what it is, how it formed and how it has changed naturally in the past. Understanding that is the key to understanding its future.

Thanks to the Environment Agency and the Geomatics Team for the provision of LiDAR data used in this blog. This data was provided to University of Hull as part of the Dynamic Humber Project.

de Boer, G., 1981. Spurn Point : Erosion and Protection after 1849. IN: Neale, J., and Flenley, J., (eds). The Quaternary of Britain : Essays, reviews and original works on the Quaternary published in honour of Lewis Penny on his retirement. Pages 206 - 215. Pergamon Press, Oxford.

Storm Surge 2013 : One Year On - Part Two : What we Learnt

by @cloudskinner

This is the second post of our mini-series about the 5 December 2013 storm surge, and its legacy for the Humber region in particular. Last week's post highlighted some of the research that had been undertaken after the surge, and why this is important for understanding the future flood risk in the Humber, especially in the context of climate change which is predicted to bring bigger and more frequent storms, as well as a steadily rising sea level. This post looks at what we have learnt about the storm surge a year after the event, and summarises the presentations given at the 2014 Humber Conference held at Hull's Guild Hall in mid November, organised by the Humber Nature Partnership. You can view individual presentations using the links on the presenters' names.

Dr Susan Manson from the Environment Agency (EA), a co-author on the research highlighted last week, began the conference by providing some of the key scientific details about the storm surge. It has commonly been held that the devastating 1953 storm surge was the baseline for these events in the Humber - the 2013 storm surge is currently the largest on record, but there have been five other events larger than 1953 in between. The fact that the devastation and loss of life has never been as extensive is true testament to the defences and plans that have been invested in since that time. For the recorded tide from the EA gauge at Immingham, which has been recording since 1963, 2013 was the highest ever water level, and by some margin.

Immingham Dock Oil Terminal - The water level recorded here on 5 December 2013 was the highest on record (by "Chris")

Susan gave some figures about the surge. 116 flood warnings were issued. 1,170 properties were flooded around the Humber estuary, but the defences protected a staggering 156,000 further from the surge. It normally takes a tidal crest more than an hour to propagate from Spurn Point, at the mouth of the estuary, to Blacktoft Jetty along the River Ouse, but the surge covered this distance in just 15 minutes – described as “like a wall” by some.

40 km of defences were overtopped but most of them held, with only two points where the flood defences themselves were breached (south of Cleethorpes on the south bank, NE Lincolnshire, and near Skeffling, on the north bank, E Yorkshire). The EA has been busy strengthening and repairing defences as fast as they can. Philip Winn of the EA described how they are using X-Rays to check the integrity of defences to ensure they are up to standard, and how the defences at Alexandria Dock have been improved (all of the flooding in Hull City Centre emerged from overtopping the 1 km stretch here). Phillip also described how the EA are looking to the future, reconsidering the Humber Strategy drawn up before the flood and going to the Government with a request for £1bn to upgrade the estuary’s defences to a 1 in 200 year standard.

Flood defences being repaired shortly after the storm surge - Chowder Ness, near Barton-upon-Humber, on the south bank, N Lincolnshire (by Jonathan Thacker)

But for many people the misery of the storm surge continues. One of the worst affected places is the small town of South Ferriby on the south bank. The defences overtopped and flooded the majority of the houses there and depositing large quantities of silt and mud inside. One of my old school friends described on Facebook how she sat on the stairs watching the water rise as her children slept upstairs. For many it was over 6 months until they could move back into their houses.

The Cemex factory was very badly damaged and a full year after the flooding it still has not returned to production. Kevin Groombridge of the firm described how the flooding did not just bring water, but also sediment and salt. These clogged machinery and corroded the electrics of the site, which were all at ground level. Having never flooded in 75 years they nearly did not heed the flood warnings from the EA, but the Director of the site insisted the workforce move. It is possible that he saved numerous lives by that decision and thankfully that is just speculation.

The Cemex Cement Factory at South Ferriby (by David Wright)

Kevin described how immediately after the flood a ‘Blitz-spirit’ emerged among the staff, and how the factory manager had to buy new office furniture, laptops, stationery and even diesel generators on a credit card in order for them to continue working. Literally everything on the factory site had been destroyed.

Agriculture was also badly hit. Andrew Wraith of Savills UK, an Agribusiness, described some of the impacts that has struck them. On their Yokefleet Estate they have 34 residences and 22 of those flooded, and 1000 acres of their 2500 were flooded to a depth of 4 ft., and a green pea factory was flooded. Some of this land was flooded for 2 -3 weeks but was alleviated by pumps. A major issue they faced was soil erosion caused not by the flooding but the speed of the water draining away.

They lost many crops, both planted and stored, and Andrew put the cost of these losses in seven figures. But Andrew also said that they considered themselves lucky – when the surge hit they anticipated that their crop loss would be almost 100% but it was actually a loss of 5-10% of the yield. He put this down to the dry conditions prior to the surge allowing for effective drainage of the damaging salt water. The timing of the surge was also fortunate, as had it had been in the spring or the summer they would have felt a two year impact on yields.

Behind Hull's Tidal Barrier on 5 December 2013 - It the water level came within 40 cm of overtopping (by @Tom_Coulthard)

And it is this sense of being lucky that I want to end this post on. If you were one of the residents in South Ferriby, out of your home for the better part of a year, you will not feel lucky, and you weren’t. If you live in one of the 156,000 properties protected by the EA’s defences, a product of decades of work and investment, you were also not lucky but fortunate that we have invested in our excellent EA. But in many ways the Humber estuary could be described as being lucky as stories emerge of near misses and close calls. It was probably only the decision by one Director at Cemex that saved the lives of their workers. The tidal barrier at Hull came within 40 cm of overtopping and putting at risk hundreds of properties along the River Hull – if the surge was timed with the high tide, rather than 2 hours apart, it could have made the difference and spilled over. If the weather in the prior days had been wet then the salty flood water would not have drained as quickly as it did, this fact saving much farmland and properties from further damage.

In all the defences of the Humber were put under considerable strain by a massive, unusual, and largely unprecedented event, but came out on top. Just. Those responsible for them should be praised that they withstood the barrage, and that there was no loss of life. But we should not become complacent – we may never witness another event of that scale again in our lifetime, but as our climate warms, becomes stormier, and the sea level rises, the chances of another, or larger, storm surge in the Humber increases. We need to continually work to keep our defences ready.

Researcher Profile - Chris Skinner

Ok, here at GEESology we have decided to tell you all a bit about ourselves and to do this in the form of a ‘Researcher Profile’. For some reason I have drawn the short straw, to put it cynically, and have to go first. The flip side of the coin is that in going first I can set the benchmark for everyone else and have a fairly free hand in doing so. I guess it is really a chance for us all to share a little bit about ourselves and what is behind our research, in particular what motivates us and why we do it. Each of us will provide one of these posts to you over the coming weeks and months, so without any further ado, here’s me –

Who am I

I am Chris Skinner, currently working as a Research Assistant as part of the Dynamic Humber project at the University of Hull. My role is develop the CAESAR-Lisflood model for operation on the Humber Estuary with the aim of providing forecasts of changes in the estuary for the coming century.

Me before my remote sensing days

What I do and Why do I do it

Last year I completed my PhD research that looked into the effects of uncertainty in satellite rainfall estimates on hydrological models. These estimates are vital in Africa, where there is a real lack of raingauges and radar that we use in the UK to predict rainfall, but as they cannot directly record rainfall they are often a little bit wrong. This in turn affects the models that are used to forecast droughts and floods. This chance of being wrong is termed by scientists as ‘uncertainty’ and this has a major impact on the people who have to make decisions.

“There are known knowns; there are things we know we know.

We also know there are known unknowns; that is to say we know there are some things we do not know.

But there are also unknown unknowns – there are things we do not know we don't know.” 

Donald Rumsfeld perfectly, although unwittingly, describing the nature of uncertainty. 

Uncertainty leads to a lack of confidence and can mean that important decisions that influence millions of people can be delayed, sometimes at the cost of people’s lives. A recent example of this was the Horn of Africa drought in 2011, which was forecast several months before any aid began to be mobilised. My research interests are in looking at ways to either reduce the uncertainty, measure it better or just communicate better to people who have to make the difficult choices – I blogged about this on my (largely defunct) personal blog over two years ago in Why do we bother?

How do I do it

How I do this is by using a lot of statistics and numerical computer models that are far too complex (and not all that interesting enough) to be talked about in detail here, but the main method I use to show uncertainty is by using ensembles of forecasts – a set of possible futures, each equally likely yet different, within the bounds of what we don’t know. From this you can produce what is known as a probabilistic forecast. It’s the difference between Michael Fish telling you there is absolutely no chance of being hit by a hurricane, and him telling you there’s a 30% chance – subtle difference but results in different (and probably better) decisions.

How did I get here

Short answer, I walked. That’s very important, as my job before I started my PhD was as a Sustainable Transport Policy Assistant at a local authority in the Midlands, and a large part of my job was encouraging people to walk and cycle more. It was fun job on the frontline, getting to organise events such as bike rides, but I did not like the look of the career ladder ahead of me. I wanted to stretch my mind so in 2009 I decided to quit my job and focus on a career in Academia.

Sustainable Transport - It can be dangerous!

At this point I hadn’t chosen a discipline, I just wanted to do something that looked like it might help people and make a difference. In the end I got the perfect PhD back at Hull, which is where I got my undergraduate degree and close to where I grew up and my family live. I’m pleased to still be a part of such an excellent department but I know one day the Academic career will draw me away to pastures new.

Wow, 500 words isn’t a lot – I never got to tell you about the time I spent in the nappy factory, the garlic bread factory, painting student houses, data entering, on Job Seekers, as a Geotechnical Laboratory Technician or in the Planning Department...

The Surge 2013

by Chris Skinner (@cloudskinner)

This blog post is going to talk about the storm surge that swept along the east coast of the UK on the 5th December 2013, last week. Rather ironically, I was going to post about problems in predicting disasters and how we mitigate against these, but this seems more topical and worthy of a post., and I hope to give you a bit of an insight into how a GEES researcher responds to live events relevant to their field.

The surge seemed to catch everyone by surprise. I checked the forecast on the Monday as my in-laws were travelling to Hull from London to visit us on the 5th, and the Met Office app suggested Thursday was going to be quite nice, but a bit windy in the far North-East. The forecast did evolve over the week, but not so much to suggest the conditions that resulted in them passing at least five overturned lorries on their journey (two and a van on the Ouse bridge alone).

On Thursday afternoon, there were warnings of a storm surge – a temporary increase of sea level caused by low pressure and high winds – that would potentially flood coastal towns on the east coast. Our local news focussed on Grimsby and Cleethorpes as being the most likely to be hard hit. Hull was just at medium risk. Myself and Prof Coulthard (my boss) watched the tide rise on the Immingham tidal gauge and compared it to the data we held from the same site during the 1953 storm surge.

The 1953 storm is THE storm when talking about storm surges in the UK. It was big and it caused extensive damage and over 300 people lost their lives. This storm was being billed as ‘the worst since 1953’, yet to our astonishment we saw the tidal gauge go up and look increasingly like it was going to exceed the level recorded back then.

As we were leaving the office, around five thirty, the first warnings started coming in that Victoria Dock in Hull was at risk. I followed the story unfold on Twitter as photos popped up showing the first signs of water overtopping the defences. The Marina also flooded and water spilled out into the Kingston Retail Park, and the home of the Hull Stingrays and Hull’s most versatile venue, the Ice Arena.

Flooding between the Marine and Kingston Retail Park in Hull Photo by @estuary_ecology

The City of Hull held its breath as high tide approached. Only the tidal barrier stood between the surging sea and thousands of properties in the flood plain of the River Hull behind. The tide crept ever upwards, lapping at the sides of the mighty barrier but could not overcome it. But it was close – only 40cm remained of that barrier, built to defend the city after the1953 surge. It had done its job, just. The tide height of 5.8m is a record high for Hull.

The Saviour of Hull! - The Tidal Barrier holds back the tide. Photo by @Tom_Coulthard (This is just one of many great photos).

The sea water eventually receded at Hull.  High tide was later in the inner estuary and badly flooded South Ferriby and Goole. The flooding continued further south, in Skegness and Boston. Another great tidal barrier, the Thames, was also needed to save large areas of East London.

Now that the waters have passed the data is beginning to be collected and analysed. What seemed to take everyone by surprise was the scale of it. Data from the Immingham gauge stopped when the level reached 8.5m*, but from the curve it looks like it would have continued to around 9.5m – 2m above the predicted astronomical tide (from the pull of the Sun and Moon), and over a metre greater than the highest reading from the 1953 storm surge (at 8.4m).

*I don't know why the gauge stopped, most of them did before high tide that night. My guess is that they either reached the top of their scale, or exceeded a threshold where it is assume too high to be accurate - The Immingham gauge stopped at around the maximum of the 1953 tide level.

This is very significant. I don’t think anyone anticipated it. As I said previously, 1953 was THE storm. For the last few months I have been working on a computer model to simulate the flows in the Humber, with one of the aims to be able to predict the estuary’s response to 1953-like events, especially in the face of rising sea levels. Much of the Humber’s defences were built after the 1953 surge so unsurprisingly the model showed they coped well. Our hypothesis was that the rising sea levels on top of that might cause them some issues, so we wanted to try and model that.

Naturally, first chance on Friday we ran our model with the tidal heights recorded on the evening before. Our model suggests that if we had been able to predict the scale of the surge we could have anticipated the flooding, even just based on this preliminary data (although a large pinch of salt is needed when interpreting the simulation below).

As bad as the flooding was, it has to be said that our infrastructure did a fantastic job. The scale of this surge was unprecedented, quite a bit bigger than 1953, yet there has not been the devastation, and thankfully, the loss of life that followed that storm. If it were not for structures like the Hull Tidal Barrier, it would have been much, much worse.

And that leaves us with a warning. The International Panel for Climate Change (IPCC), uses different models to try and predict future sea level rises for the next 100years, and the 'Best Case Scenario' - where greenhouse gas emmissions are cut immediately - would likely cause a sea level rise of 40cm. This is the capacity left over on the Hull Tidal Barrier. When we consider that an increase of 60-80cm is probably a better estimate, the ability of our infrastructure to manage this size of event in the future needs to be considered. It maybe that this storm surge is an event that won't be repeated in our lifetimes, but it now stands as THE storm we’ll be using the measure future resilience and it pushed us right to the edge.

Getting Animated

Getting Animated by Chris Skinner (@cloudskinner)

The formal presentation of research in academia is pretty traditional. I doubt it has changed much in the last 500 years, if not longer, and for a progressive sector of society it really does not look set to change. Basically, you get your results, write it up as a paper, some experts look it over and request more details or changes, you do them, they pass it, you get published.

The published article then goes into a journal. Most of these are still printed but are available, usually as a PDF file, electronically. This is where the embrace with the modern world ends. I mainly read articles either on my computer or my tablet – most articles are formatted into two columns on a page which makes it very awkward to read off a screen. So optimisation for electronic presentation is not high on publishers’ agendas it would seem.

But are we missing out? A magazine I have been reading since I picked up my first copy in October 1993 has changed many times in the last two decades. It isn’t a science publication but is related to a hobby of mine, and last year they started publishing a version of the magazine optimised for the iPad. They could have just bunged out a PDF of the paper copy, but they knew that the new technology provided them with a platform to support more content. In place of a photo there is an interactive 360º image, instead of a price list for new products there are hotlinks direct to their entry on the online store, plus there’s additional videos, interviews and zoom panels. If the magazine contains typos or erroneous details, it is automatically updated. The company have started rolling out this idea to their other printed materials.

What if these ideas were used in academia? What sort of content could we include? The most immediate thing that springs to my mind is animations. I produce tonnes of them, and conference presentations aside, they rarely get seen outside of my research group. Why do I make them? Because they are useful for very clearly showing how systems work, if your model is operating how it should or demonstrating patterns in data - (*Thanks to @volcanologist for pointing out that animations can sometimes be submitted, and hosted on a publisher's website).

Take for example some work I have been doing on historic bathymetry data from the Humber estuary. Bathymetry data are readings of water depth at the same tide level, and I use the data to create maps that show the shape and elevation (heights) of the bottom of the estuary. To find out more about what estuaries are, take a look at Sally's previous blog.

Provided by ABPMer, the data spans a period between 1851 and 2003 – I processed the data, calculated rates of elevation change between each sampling period, and from this produced yearly elevation maps. By putting these together as an animation I could see the evolution of the data (it is important here to stress the difference between ‘data’ and reality - not all areas of the estuary were sampled by each survey, and the number and locations of reading varied. Much of the change seen in the video is because of this and not because the Humber has actually, physically, changed in that way).

What immediately struck me was the contrast between the middle and the inner estuary. The middle estuary is the part between the Humber Bridge and the sea, where the estuary’s course deviates southwards – it is remarkably stable over the 150 or so years. The inner estuary, from the Bridge towards Goole, sees lots of internal changes – driven by interactions between the river inputs and the tides – but overall very little change. The Mouth of the Humber, the part closest to the sea, looks to see little overall change, but most of the variations seen in the animation are due to differences in sampling point in the data, and not actual changes. Similarly, changes around the banks of the estuary observed in the animation are most likely caused by sampling difference in the surveys, rather than actual elevation changes.

I have recently been continuing work on adapting a landscape evolution model, Caesar-Lisflood, to model the Humber estuary, and a big step towards this is to accurately model the tides as they are observed by tidal stations recording water depths. Numerically we can do this, but it is important to check that the model is representing the tides in a realistic way - this is a very important step in making a model as it has to be able to accurately simulate observed behaviours before you can experiment with them. Again, animations are a really useful tool for doing this.

The video above shows the variations of water depth throughout several tidal cycles, as modelled, with light blues as shallow and dark purple as deep water. The model changes the depth of the water at the right hand edge in line with water depth data recorded from the Spurn Point tidal station near there. The water then 'flows' from there, down the length of the estuary as the depth increases, and vice versa - this simulates the tides going in and out.

From this I can tell that the model is operating well, as the tide is advancing (coming in/going up/getting deeper) and receding (going out/down/shallower) as expected, throughout the whole region and not just at the points where the tidal stations are located. You'll notice that the early part of the animation shows the estuary filling up with water - this is part of something called 'spin-up', where you let the model run for a period of time to get the conditions right before you start the modelling. In this case it is a 'day' as the water levels gradually builds, filling the estuary.

Another check would be the velocity of the flow as the tide floods and ebbs - this is the speed with which the water is moving (both in or out). The velocity should increase as the tide advances or recedes, but slack water (where the water is hardly moving at all) should be observed at high and low waters. If the model is working as expected, the area of slack water should progress from the sea and up the estuary towards Goole. From the video below, this is seen to be the case. Light blue shows low flow speeds, and darker purples higher flow speeds. The video shows the same modelling procedure as the previous video.

This type of content is really useful to me as a modeller. It is also really useful for presentations as I can show a group of people something that takes a few seconds, yet would probably take a lot of slides and quite a bit of explaining. If academic publications were to begin to include enhanced content in peer-reviewed publications, I believe this could advance the communication of research, not only to other researchers but also to the wider public. For now, Blogs, like the GEES-ology one here, are the best outlet. I hope you enjoyed the animations!