The Science of the Seabed

We know more about the surface of the moon then we do about the oceans on our planet. 

And yet, seabed mapping is a vital part of maritime safety and the economy that is part and parcel of our every day lives.

We've been exploring the whole topic of hydrography and why it matters...

Transcript

Heather: Hello and welcome to another Maritime and Coastguard Agency podcast.

Today we're talking about science. You might be thinking what has science got to do with the MCA? You're about maritime safety.

Well you might not see it but science is definitely there and it's helping to keep us safe as we travel on ferries and cruise ships, fishing boats and yachts. And it helps to make sure our new cars, new fridges, medicines and food get here safely.

Still puzzling it out?

Well let's hear about the science of the seabed from Andrew Cole that who's our head of hydrography and meteorology.

Andrew: We undertake a national program of seabed mapping around the whole of the UK waters and all the data that we collect is being fed directly into updating nautical charts and all the publications so that the mariners have the most up-to-date information so they can plan their sort of safe passage, Their safe transport. the efficiency of their transport routes and providing information on where the seabed is so that they don't hit any features or mobile banks. We're protecting the lives of the mariners on board and also the environment so we don't have um, pollution incidents.

Heather Put like that, it seems quite simple really, maritime safety relies on the science which informs nautical charts and maps. The importance of this data hasn’t changed of course, but the way it’s collected, has. Andrew Colenutt again.

Andrew: Yes, I think if we go back a hundred years or so the seabed would have been mapped [in inverted commas] using a lead line, which was basically a big lump of lead covered in very sticky glue. The lucky sailor would unpay it out on a very long rope until it hit the seabed and then you count how many metres or feet or fathoms it was and you make a note on the chart then. 

Since then technology has developed somewhat. We moved into single beam echo sounder some thirty forty fifty years or so ago but for the last twenty or so years we've been using the latest equipment which is multi-beam echo sounder and the amount of data the amount of soundings that we are collecting on the seabed um is enormous. 

So we’re mapping the seabed in very high resolution and that's providing not only very accurate data but it's providing the mariner with an awful lot of confidence in the information that they're on the charts that they are then using. 

All this data is not just being used for navigation safety and mitigating navigation risk but that data is then freely available and being used by a whole range of different applications across the whole of government, things like habitat mapping, you need to know where your protected reefs are or endangered habitats that need to be protected from maybe fishing activities. It is used for fisheries management understanding where sediment is and where rock is so you can identify areas that are mobile where the banks are mobile, how mobile the seabed is so that you know in an emergency if you know if you're ah a cruise ship or a tanker and you need to anchor because your engines are failed then you know you've got information on the chart that will tell you whether you know the anchor is going to hold in certain places or not. 

We also provide information on tide levels and tidal streams and that's all fed into yeah, a whole range of different applications but one of the key ones from the from the MCA's point of view is if you've got people in the water and they're drifting with the tidal current. Having that information underpins the search and rescue activities that also feeds into a pollution control. If you’ve got an oil an oil leak um occurring and you know what the wave conditions and the tidal streams are that that can be modelled and fed into recovery plans of how that that pollution is going to be controlled and managed.

Heather: From that lone sailor with his lead weight to the high-tech soundings that are taken in the 21st century, the scientific data recorded is vital for so much of our maritime life. Just how vital becomes more clear as Andrew explains how it’s done and how what’s found has changed.

Andrew The MCA is the largest commissioner of seabed mapping in the UK. We have the civil hydrography program - so basically anything that isn't defence, we are interested in from a navigation risk point of view. 

 We have the three elements to the civil hydrography program. The core element is the routine resurvey. These are relatively small areas that we survey pretty much on an annual basis and these are targeted at areas that are very mobile. There are sandbanks or gravel banks that are exceedingly mobile and they're moving every hour and then they can shift position and height very quickly and continually throughout the year.

 Quite a few of these areas are on the approaches to some of our largest ports like London so the survey area focuses on key areas of mobile seabed and also where the depths are the under-keel clearance. So, the amount of water below the hull of the vessel and the seabed in places is only a metre and a half so identifying those areas and keeping a very close watch on the controlling depths and the least depths in those areas is absolutely critical for making sure that the marine traffic can navigate safely to and from the UK 

There’s a huge proportion of the UK's economy that is driven by the maritime sector so you know providing up-to- date information to that whole sector ensures that everybody gets the deliveries to the UK that they need. 

 We also map the rest of the UK waters which are more on a longer term basis. Our contractors using their own vessels and their own personnel and equipment, undertake these surveys in accordance with a very strict survey specification that we've developed with our colleagues at the UK Hydrographic Office and our counterparts in other countries to make sure that we are achieving and generally exceeding the international hydrographic organisations’ standards for surveys. All our data is collected to this specification, it's all validated to make sure that it meets these high requirements. They’re high resolution detail surveys really accurate, really high quality, world-leading in terms of the program of surveys that we undertake as well as the equipment and the expertise of our contractors and our colleagues, both within the MCA and at the UK Hydrographic Office.

Heather: How much change do you see year on year in terms of what's coming back from this this data around our coasts, around our sea beds?

Andrew: It does vary. There are some areas that we survey and we're basically confirming that the depths haven't changed, that the seabed hasn't changed and that's just as important as knowing where it does.

There are particular areas around the UK where the seabed is exceedingly mobile, so you know if a vessel is surveying say a hundred metre long line, by the time they've finished that line and they've turned and they're coming back down the next line, the seabed has shifted already. These are quite sizable banks of sediment, generally sand or gravel or a mix. Their position is shifting all the time and occasionally depending on the prevailing wave conditions and tidal currents et cetera, if It's a prolonged period of stormy weather, then those banks might well build up. The height of those banks will change and therefore the under-keel clearance will be reduced which makes it more challenging for the navigator on board, particularly the larger vessels. They need to know where these banks are how much clearance they're going to have. There are occasions where vessels can only enter ports or leave ports at certain states of the tide. If it's on a high tide, they’ve got that extra centimetres or a foot of water that is going to be the difference between them approaching that port fully laden with all these hundreds of cargo containers or not.

If they need additional water, then they're going to have to wait for the tide and that obviously has huge implications in terms of how the port is managed and you know time is money. Knowing how these banks are changing and where they are is fundamental. 

All of our surveys are driven by a whole range of different navigation risk parameters, things like the amount of vessels that are operating in an area, the routes they're using, what the tide range is, the mobility of the seabed, the type of seabed and under keel clearance etc. 

Wrecks are an important element within these areas, identifying where these wrecks are. We need to, capture that and make sure that those are on the charts and because the equipment is so good now, it's cutting-edge and the amount of information we are collecting is incredible. I mean it's mind-blowing how many soundings we're collecting within each square metre of the seabed.

We found a wreck on the approaches to quite a major port in two metres of water and it's just a minor miracle that nothing had hit it before. So, the fact that we are now doing these really comprehensive high-resolution surveys, we can't afford not to.

When you put it like that, the science of the seabed suddenly becomes a lot more relevant to our everyday life. I asked Andrew whether it was what drove him on.

Andrew: There’s an increasing and acknowledgement that this data has a value. The use of that data is increasingly important to the UK PLC and it's inspiring the next generation of surveyors to get involved. There's an awful lot of seabed around the UK that needs surveying but globally there are international programs looking at mapping the oceans as much and as quickly as possible.

Considering that 70% of the planet is covered by oceans, we know more about the surface of the moon than we do about our own ocean seafloor. 

There's a huge amount of work to be done and we have the technology and we're increasingly having the people to do that work. I mean it's a fascinating area, exploring areas that have not been surveyed before, uncovering seabed features or wrecks that have not been identified before. It's very exciting. If you like pushing the frontiers of technology and innovation and also sharing that data. The data sets are huge, they can be quite complicated, but we need better ways of shouting about what we're doing, what we're finding, how it can be used. 

By plugging into schools and universities we are wanting to inspire the next generation of hydrographers and mappers, people that know how to use data, how to understand the data and how to make that data really accessible to the general public as well, so they realise the importance of science and data. That will underpin how mapping the ocean will play a huge part in tackling issues to do with climate change. It’s not just navigation risk that you know we're providing a dataset for, it's feeding into a whole myriad of different applications that you just don't know how they're going to spin out and escalate. It's a very exciting time working in the seabed mapping sector at the moment .

Heather: You’ve been listening to the Maritime and Coastguard Agency podcast about the Science of the Seabed. Until the next time, goodbye.