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Blog: Hydrography, land surveying at sea, Who's in?
Hydrography, land surveying at sea, who’s in?By Anton Schutte, director Geo-ICT Training Center, Nederland, Apeldoorn, February 2020 Back when I was studying geodesy in Utrecht, I discovered that the profession of land surveying could be a very adventurous one. Many of my fellow students went abroad for internships, for example, doing surveys in places like Saudi Arabia. Sometimes, quietly to myself, I can be quite judgemental about these youngsters. I find myself thinking: do they really expect it all to simply be handed to them? To be given whatever it is they decide they want? That they don’t seem to realise that some things require blood sweat and tears to achieve. That, when faced with any, even the smallest, setbacks, they can just give up, and go soul searching in their little suitcase of burdens, while some empath holds their hand. But then, when I look back to how I was when I was in my twenties, I have to adjust my views. Because, really, I was rather spoiled too, and often scared as well. During my internship at engineering firm Oranjewoud (now part of Antea Group), for example, I once refused to join a team on a week-long trip to an oil rig in the North Sea to carry out hydrographic surveys. Even today, I carry that refusal with me in my geo-suitcase. The reason was that it scared me. That I was afraid that I wouldn’t understand anything, and it would all end in failure. No, I said to myself, then I would rather go home on the weekend, drink beer (and throw it around) at a Normaal concert with my friends and my girlfriend. With my girlfriend I did overcome my fear, our ‘wedding boat’ set sail in 1986. We’re sailing the high seas together. And we’ve become a lot wiser since then. Fear is often a sign that you need to take action. If you’re physically on that cliff edge, staring into the depths, fear is the signal that tells you to take action. Step away from the edge. In our wealthy and free lives, psychological fear plays a far greater part. That is fear that is instilled by our own thoughts and 9 times out of 10 it is complete nonsense. But with this fear too, you need to take action. This fear is a sign that something is important to you. This fear is something you need to overcome, by pushing through it. So, step over that edge. And why not? You’re not really in any (physical) danger. If I were younger, I would sail all over the world to do as many of those crucial surveys as I could. Over 70% of our planet consists of water. Climate change is currently causing a lot of shifts and changes. Think, for example, of how rapidly coast lines are changing. The hydrography profession focuses on describing bodies of water and the ground underneath them. You could call it land surveying on the water. The most important aspects of hydrography are measuring the depth, the composition of the water and the seafloor, the tides, the waves, and the currents. The surveys are often needed to allow ships to navigate safely, or to serve as the ‘eyes’ of dredgers and offshore construction projects. Below, I will provide some examples of land surveying on the water. Collecting information in connection with gas and oil extraction Before a refinery can start up, a platform must be built, and pipelines need to be laid to transport the oil or gas. Before that, the hydrographer needs to mark off the area and collect all required information. This phase comprises a 2D seismic study. Then, a ‘pilot’ drill to the source is planned to verify seismic interpretations. For that pilot drill, a ‘site survey’ is carried out to obtain more detailed information about the seafloor. High-frequency Geophysics is used to determine whether there is any gas present on the surface. The presence of such gas poses a serious problem, because it could cause an explosion. Then, a 3D study takes place to obtain even more information about the oil/gas source. Surveys during the construction of the platform If it turns out that the field is suitable, another 3D seismic study is conducted, but now in great detail. The hydrographer marks out the drilling platform and carries out continuous surveys during the construction of the oil rig. Construction of pipelines A pipe layer, or pipe-laying ship, is a ship that is used for the construction of undersea pipelines. Most undersea pipelines are constructed by ships specially designed for the purpose. A common method is for the individual segments to be welded together one after the other on board. The ship moves forward, while the pipeline disappears into the water behind the ship. Dredging coastal areas To maintain the depth of waterways and the accessibility of ferry terminals, docks, and quays, dredging takes place in the Wadden Sea and some of the ferry terminals around the Wadden Sea. The dredge is then returned to a number of fixed distribution locations. Coastal reinforcement Nine million people in the Netherlands live in the coastal area. A large part of that area is below the current sea level. Roughly one third. The lowest point in the Netherlands, Zuidplaspolder in Zuid-Holland, is a full 6.76 m below AOD (Amsterdam Ordnance Datum). Far enough below that we can safely conclude that it is very important for the Netherlands to keep a close watch on the coastline. Making nautical charts A nautical chart is a map that contains as much information as possible that is important for safe navigation at sea and other bodies of water. In inland navigation, similar charts are used. Supplemented with Sailing Directions, Lists of Lights, and other publications, they help the navigator prepare for a safe voyage. Depending on the scale, the chart contains information about water depth, soil types, the coast line, areas that fall dry with the tide, the height of landmarks, cables and pipelines, buoyage and lighthouses, navigational hazards such as wrecks and shallow areas, sea currents, tides and tidal currents, magnetic directions, and harbour infrastructure. Shipwrecks Seafarers require information about waterways, the seafloor, and underwater hazards, such as shipwrecks. It is important that shipwrecks are mapped. They’re like time capsules. They tell us something about the time they were lost. There are very rare matters that you need to watch out for. That is why you need to know where they’re located, so that you don’t end up destroying them, for example when constructing wind farms or gas pipelines at sea. We do not know exactly how many shipwrecks there are in the North Sea and Wadden Sea. Deep sea mining Deep sea mining is a fairly new mining method, where minerals are mined from the seafloor. The mining sites are usually situated around large areas of manganese nodules, or near dormant or active hydrothermal vents. These vents contain valuable metals like silver, copper, cobalt, gold, magnesium, and zinc. Deep sea mining is not yet practiced on a large scale. But there are various companies that are working on studies into the feasibility of deep sea mining and the environmental damage that it might cause. Marinas The leisure industry is undergoing rapid growth. This creates a lot of work for hydrographers in the marking, mapping, improving, deepening, and securing of marinas Wind farms In the construction of wind farms at sea, hydrographers are constantly working on determining the right position and to assist with pile-driving and the placement of markers and laying of land-bound cables. How can I become a hydrographer? Above, I’ve provided some examples of the work a hydrographer might do. The profession is a lot more diverse and everywhere in the world, fresh new hydrographers are needed. In the Netherlands, we offer a practical course to become a Hydrographer. Our CAT B accredited course in Hydrography, which we organise in collaboration with Skilltrade is unique, and people from all over the world can come to the Netherlands to study it. The course is recognised by the International Hydrographic Organisation (IHO) and completion is rewarded with an accredited CAT B certificate. After the course, you’ll work on a ship and during practical training, you’ll need to perform several additional assignments to obtain the certificate. You can complete the following two free MOOCs to determine whether you are right for the profession, meaning, whether you have adequate prerequisite knowledge of mathematics and physics.
- Mathematics for Hydrographers
- Physics for Hydrographers
- Introduction to Hydrography
- Geodesy for Hydrographers
- Bathymetry for Hydrographers
- GNSS for Hydrographers