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.

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!