Paying Tribute to the Hard Life of Peat Dredgers

Sculpture ‘Verveners’ by John Rijnen
Sculpture ‘Verveners’ by John Rijnen

It’s been a while since my last update. Don’t worry. All is well. The delay was due to my change in habitat. Moving can be draining attention and creativity, but can also create opportunities for exploring the new neighbourhood. And that is exactly what I will share as this first post. One of the first dredging related discoveries was a sculpture on a roundabout nearby. Probably most passers-by will not notice it or at most will be puzzled by the strange flat figures. To us, as dredging community, we immediately recognise the typical posture of manual dredging. Intrigued by the unexpected discovery of dredging art at this location, I went on an investigation on the background of this statue.

Sign at sculpture ‘Verveners’
Sign at sculpture ‘Verveners’

The sign at the sculpture did reveal some details on the name, date and artist of this monument1. Obviously, the topic of this statue was a tribute to the people who have been working as peat dredgers and contributing to the wealth of the town. It is also a reference to the origin of the current geography of the municipality: lots of lakes and ponds that are a recreational area for the population and a resting place for nature, that were unbelievably all excavated manually over ages.

The most characteristic feature of the sculpture are long poles2 in combination with the posture for back breaking manual labour. The long pole has a hoop at the lower end with some kind of fishing net attached. The hoop is used to scrape sediment (in this case peat) from the bottom and collected in the pouch. Mud and peat are sticky enough to stay in the net for vertical transport, but the flexibility and openness enables easy discharge. For peat dredging the material was scooped up on shore and dried3. For maintenance dredging, the material was brought on board and discharged at a convenient disposal location4. The Dutch dredging industry cherishes this and remembers it with all kinds of small statues found in many offices.

Paper weights about manual dredging with a ‘baggerbeugel’ (Credit: Hendrik Jan de Kluiver)
Paper weights about manual dredging with a ‘baggerbeugel’ (Credit: Hendrik Jan de Kluiver)

Manual dredging shaped much of Holland’s geography, either the canals and lakes or the reclamation of marsh into pasture land. It has been identified as a typical Dutch tradition. But is it?? Preparing this post, I’ve discovered it is not. Several references say that we did not invent the ‘baggerbeugel’2. Before we started to use it, it has been applied already for ages in East Anglia5, which had a very similar landscape. Already from the tenth century, peat has been excavated from the Fenlands and later on from the 14th century, they started manual dredging already. Only later on in the 16th century Holland started to take over this practice. And in good Dutch tradition, we refined the trade and even exported consultancy on these projects back to England!

Stills from an instructional video on peat dredging (Credit: modified from Open Beelden Project)
Stills from an instructional video on peat dredging (Credit: modified from Open Beelden Project)

Peat dredging is a laborious procedure and later on, this industry was mechanised. There is a nice video explaining about peat dredging in the Netherlands. Especially the hydraulic dredging starts at 08:10 into the video. All processes in a regular dredging project are identifiable: a) dredging, b) discharge, c) bulldozering, d) compacting, e) drying and f) further transport of the merchandise.

Viewing a video is one way to experience manual dredging. In the dredging garden of the National Dredging Museum6, there is an exhibit to experience this trade first hand.

Visitors experiencing manual dredging in the National Dredging Museum
Visitors experiencing manual dredging in the National Dredging Museum

References

  1. De oude tol, Rotondekunst
  2. Baggerbeugel, Wikipedia
  3. Vervening, Wikipedia
  4. Barges, IADC
  5. A Tale of Norfolk Peat Cutting, Norfolk Tales, Myths & Beyond
  6. Bagger Praktijk Tuin, Nationaal Baggermuseum

See also

 

 

Historical Origins Exhibition at the WODCON: the Beijing-Hangzhou Grand Canal

Last section of the Grand Canal in Beijing.

Another impressive dredging accomplishment in ancient China is the well-known Beijing-Hangzhou Grand Canal. Of course this was also featured in the Historical Origins of Dredging in China exhibition at the latest instalment of the WODCON in Shanghai. During our visits to Shanghai1 and Beijing2, we’ve seen the canal at both ends, although they are an impressive 1797km apart.

Grand Canal exhibit in the Historical Origins exhibition at the WODCON.

Triggered by the sign board at the exhibition, I wanted to know more about this immense project. 2500 Years ago, the designation of Beijing as capital of China, was followed by an increase of the population. Any further expansion of the city was limited to the resources available nearby for supporting all these new citizens. The great rulers of ancient China, wanted to access the supplies of the south, where food and crops were abundant. It was decided to dig a canal, all the way from Hangzhou to Beijing3. The importance of the canal for the ancient Chinese civilisation is equivalent to what nowadays the Intracoastal Waterway means for the New York area. Although the ICW is an even longer waterway, it consists mostly of natural water bodies. This makes the Beijing-Hangzhou Grand Canal the longest dredged canal in the world.

Map of the various sections of the Grand Canal (Credit: Wikipedia).

The sign falsely boasts, that the Grand Canal is the oldest canal in the world. Sorry, that honour belongs to our ancient Egyptian engineers4. But the Chinese can be proud their canal is still in use today, whereas the Canal of the Pharaohs is now only used for irrigation. The Beijing-Hangzhou Grand Canal in China is therefore actively maintained. Partly even the traditional way: by hand.

Maintenance of the Grand Canal in the last section in Beijing.

After establishing the age and the length of the Grand Canal, there is another property that might be interesting: the width. I’ve seen sections varying between 10 and 50 meters. Probably the range is even more. Initially the width was depending on the local circumstances, requirements for navigation and possibly the limitations of manual labour.

Explanation on parameters for channel width determination.

Today, the width of a canal can be carefully engineered and a customer may require that the contractor delivers the width exactly. Therefore, it is necessary to know exactly what the capabilities of your cutter suction dredge are. Both at the lowest depth and at shallower depths for the slope of the sides. Knowing the geometry and the dimensions of the cutter suction dredge, one can calculate the reach with complicated trigonometry. Or one can build a model in the 3D environment of the design of the project and see what is possible5. There is also another clever solution to this problem. For every cutter suction dredge we designed, we developed a geometric scale model. It takes into account ladder depth, spud carriage length and swing angle. The result is the canal width that is possible for that cutter suction dredge. A further simple multiplication of canal width, cut height and channel length reveals the production volume. Either onboard or at the office, it provides a nice little instrument for production estimation.

Geometric scale model of a CSD650 for canal width calculation.

References

  1. WODCON, Damen
  2. Historical Origins Exhibition at the WODCON: Yu the Great, Discover Dredging
  3. Grand Canal (China), Wikipedia
  4. The Ancient History of the Cutter Suction Dredge ‘10th of Ramadan’, Discover Dredging
  5. Positioning and Survey System, Damen

See also

 

 

Historical Origins Exhibition at the WODCON: Yu the Great

Statue of a bronze Ox, commemorating Yu the Great.
Statue of a bronze Ox, commemorating Yu the Great.

Traveling all the way to the WODCON in Shanghai China1 presented an excellent opportunity to visit this wonderful country. So, after the congress, we travelled to Beijing, to visit the tourist highlights. However, as obsessed with dredging as I am, I can find inspiration for the stories on this website anywhere. Take for example this bronze ox. Quietly staring at the Summer Palace2, it might easily be overlooked by the innocent visitor. But it is very relevant for our dredging community. It is to commemorate the great Yu, who subdued the flood with the first dredging project in the world3.

Exhibit about Yu the Great at the historical origin show at the WODCON 2019.
Exhibit about Yu the Great at the historical origin show at the WODCON 2019.

Next to the interesting presentations and the conventional dredging exhibition, the WODCON organisation arranged a nice little exhibition on historic origins of dredging in China. Of course the first exhibit was about Yu. Intrigued by this little piece of information, I asked around and did some research on the internet to puzzle together, what the sign did not tell.

First of all, there are that many records4. It has been so long ago, there only remains oral tradition to consult. The facts are inconclusive, even claiming it is just a mythical tale. So, we will approach this Mythbuster style. Examine the myth and the facts. Test it. And if it does not provide the expected results, take it to the extreme. Unfortunately, we will not blow things up at this time. Maybe we will do that later on another topic.

Sign at the bronze ox at the Summer Palace, Beijing.
Sign at the bronze ox at the Summer Palace, Beijing.

The story depicted on the information sign is not completely in line with the historical data available. Let’s start with the ‘iron’ part of the ox. According to several sources, the adventures of the Great Yu may have happened 2000BCE. That is in the middle of the Stone Age5, at best early Bronze Age. Also, it was usually not ‘to ward of the floods’. Those were mitigated by a framework of dikes, dams and overflow weirs6. When an ox was mentioned, it is about protecting these civil works. But nowhere can I find a solid explanation about what an ox can do to protect a dike or how this procedure would contain the river in its human designed trajectory.

Water buffalo at the Li River, near Yangshuo.
Water buffalo at the Li River, near Yangshuo.

Even today, one can find bovine creatures standing in the river. And from a distance they might easily be mistaken for a field of boulders. Conversely, a field of boulders might also be mistaken for a herd of oxen…

Boulder field or rudimentary groyne in the Li River, near Yangshuo.
Boulder field (or rudimentary groyne?) in the Li River, near Yangshuo.

So, my hypothesis is: ‘the Great Yu constructed his dikes and protected them with groynes against erosion7. When the uninitiated had to describe what he constructed, they compared those with water buffalo and the oral tradition morphed this into iron oxen.’ This is only my opinion after just a little research and it is up to educated historians with their research to disprove it.

Discussing these civil works and the containment of rivers, made me think of my beloved home country through the famous Dutch poem ‘Memories of Holland’8.

Excellent masterpiece of hydraulic engineering to contain a river and example of modern groynes. (Credit: van den Herik-Sliedrecht).
Excellent masterpiece of hydraulic engineering to contain a river and example of modern groynes9. (Credit: van den Herik-Sliedrecht).

References

  1. WODCON, Damen
  2. Summer Palace, Wikipedia
  3. Great Flood (China), Wikipedia
  4. Yu the Great, Wikipedia
  5. History of China, Prehistory, Wikipedia
  6. Chinese Myth of the Deluge, China Heritage Quarterly
  7. Groyne, Wikipedia
  8. Herinnering aan Holland, David Reid Poetry Translation Prize
  9. Kribverlaging Waal Fase 3, Van den Herik-Sliedrecht

See also