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

 

 

HYDRO 2018 Gdansk: Selecting A Dredge For Your Reservoir Maintenance

Barrage du Ksob, M’Sila, Algeria with a DOP dredge 350

This week, I am here in Gdansk for a presentation on the HYDRO 2018 Conference1 and assist at the Damen booth at the corresponding exhibition. The paper and the presentation are already prepared and I am very excited to do the presentation, but I can’t wait till tomorrow and I like to share the story now, already. So, you, as my favourite audience, will have my personal spoiler after so many teasers have been floating around2,3,4.

General modes of siltation at the usual location in a reservoir

The thing is, dam maintenance and reservoir restoration is something already long on my attention list. Back already in 2008, I wrote a paper on this subject for the CEDA Dredging Days5. Over and over we’ve conveyed the message on various platforms, that dredging might be a viable solution for sedimentation problems in reservoirs. Usually, the solution by dam owners and operators is to flush, sluice or store the sediment. This looks horrible from a dredging perspective, but it is also to the environment. You either smother or starve the downstream river with sediment. As a right minded dredge enthusiast, you see many possibilities to dredge such a project. Immediately we can identify what dredge to use on which location for which purpose.

Selection of applicable dredges for reservoir dredging

If you are very close to the dam and the length of the discharge line allows it, you might even not need a dredge pump. (No wear parts!) It is a so called siphon dredge. But as soon as there is some further transport involved, either distance or uphill, you need a dredge like a cutter suction dredge or a DOP dredge. For even further discharge, you might employ a booster for increased discharge pressure. If the distance becomes very far, you might have to resort to grabs and barges.

Water injection dredging principle and example (this example would be too big for a common reservoir)

As an intermediate solution you might even consider using a water injection dredge. Usually the reservoir is in the mountains and a bottom gradient will be present, enabling the required gravity flow. The actual dredge should have created a silt trap where it can collect the inflowing material from the water injection dredge. Than it can handle the material as usual.

Alternative uses for the dredged sediment a) silt farming as fertile additive b) gravel extraction for concrete

Off course, the dredged sediment belongs to the river and the best thing would be to gradually release the sediment after the dam. But there might be conditions, where it is beneficial to extract the valuable fraction of the sediment and use it for agriculture or as aggregate in the construction industry.

Dredge selection diagram for reservoirs

We noticed, that it is often difficult to convey to dam owners and operators which dredge to select for which job. Sediment is seen as a liability and not as an asset and they rather neglect issues associated with the sediment. So, I made an attempt to have a plain and simple selection diagram. That is the core of my manuscript. But my objective is, that we will see many beautiful dredges contributing to a sustainable and viable operation of hydropower dams and reservoirs.

New DOP dredge family

References

  1. HYDRO 2018: Progress through partnerships, Hydropower and Dams
  2. LinkedIn Teaser, Saskia den Herder
  3. Damen: Spotlight on Hydro Power Dam Maintenance
  4. LinkedIn Teaser, Olivier Marcus
  5. Multi Functional Small Dredging Solution For Maintenance Of Deep Irrigation Reservoirs And Hydro Power Dams, CEDA

See also

The Ancient History of the Cutter Suction Dredge ‘10th of Ramadan’

Cutter Suction Dredge ‘10th of Ramadan’

Last week I was away to Egypt. I have some emotional ties with Egypt. It took me the better part of seven years, to deliver the cutter suction dredge ‘10th of Ramadan’1, to the Suez Canal Authority. This all started from the qualification tender, building it at the Port Side Shipyard in cooperation with DTC, eventually all the way through the guarantee period. At a certain moment, I was so occupied with this dredge, I even prepared a paper model of the vessel in my own spare time.

Presentation of the paper model of ‘10th of Ramadan’

This nerdy pastime served a practical purpose. The specifications of the construction and the requirements for the installed equipment, were very complicated and it helped me to understand the problems in the hull construction before they arose in reality. The environment of the Suez Canal demands some specific requirements concerning tank and space division. Furthermore, the SCA is very aware of the capabilities of the crew and demands corresponding considerations on equipment and systems. To fit this all in the prescribed box, was quite a puzzle. The normal operational environment of the dredge is maintenance on the shallow shelves of the Suez Canal.

Example cross section of the Suez Canal

The maximum box size, that made the design so tricky was determined by a certain lock to access the irrigation system along the Suez Canal. On the west side of the canal, water from the River Nile is diverted to the fertile land over there. Already in ancient Egypt, this was a much treasured area. Joseph gave this area than called Land of Goshen to his family to live there2. Senausert III, Pharaoh of Egypt (1874 B.C.) also saw the potential of this area and used it to established a connection, between the Mediterranean and the Red Sea by linking branches of the Nile to the Bitter Lakes3. Subsequent kings renovated and expanded the canal, that eventually became known as the ‘Canal of the Pharaos’4. Unlike the international importance of the current Suez Canal, the Canal of the Pharaos was mainly used for local transport of produce of the irrigated land and construction stones from quarries on the Red Sea coast to the monuments along the Nile.

Canal of the Pharaos (Credit: Wikipedia)

In fact, the ancient Egyptians might be called the inventors of dredging canals for transportation, preceding the Chinese by about 1000 years5. Parts of the canal are still there. They are now incorporated into the irrigation system, that the Suez Canal Authority has to maintain, next to the big Suez Canal. In a way, I feel honoured, that the dredge that was once only a figment of my imagination and became a reality, will one day keep this ancient piece of Egyptian history alive and preserve it for future generations. Well, that may be a bit presumptuous, but I still feel proud over this dredge and have fond memories of the people from the Suez Canal Authority I have worked with.

OK, I may have pestered my colleagues so much with my stories about Egypt and my little dredge, they even prepared a cover for a book for me to write about it on my work anniversary.

Cover page ‘Mark Winkelman as Egyptian’ (Artwork: Gert Kraaij)

References

  1. ‘10th of Ramadan’, DredgePoint.org
  2. Genesis 45:10
  3. Canal History, Suez Canal Authority
  4. Canal of the Pharaos, Wikipedia
  5. History of Canals in China, Wikipedia

See also