My WODCON 2019 Presentation: Launching Robotic Dredging

Me, presenting my WODCON 2019 contribution.
Me, presenting my WODCON 2019 contribution.

Yesterday, I gave my presentation at the WODCON 2019 in Shanghai1. The WODCON is the triannual world dredging conference, were everybody in the dredging industry meets and exchanges knowledge and ideas. Just as I mentioned in my New Year’s post, I sometimes like to delve into some old archives, get inspiration and hatch new ideas2. So did I for this presentation.

Overview of the ‘Ketelmeer’ (Credit: Google Maps).
Overview of the ‘Ketelmeer’ (Credit: Google Maps).

A seminal dredging project concerning environmental dredging is the ‘Ketelmeer’ clean up dredging project, resulting in the creation of the contaminated sediment storage depot in the artificial island ‘IJsseloog’3. As careful removal of the contaminated sediment required novel dredging techniques, the government challenged the dredging industry to test four innovative concepts. The results were evaluated by the institute now called ‘Deltares’ and published in a report4. The original conclusion of the report was, that the auger dredge was the best in reducing the turbidity. Later, the bigger auger dredge ‘HAM291’ was constructed and used to actually clean up the lake. With the knowledge and the experience of the auger we also developed a range of auger attachments for our DOP pumps5.

Traditional auger attachment for a DOP pump excavator combination.
Traditional auger attachment for a DOP pump excavator combination.

Reading the Ketelmeer report again, it occurred to me, that one parameter had not been properly accounted for: the size of the dredge. The auger dredge was by far the smallest dredge in the game. With a weighed scoring method, the dredges were also compared in size and installed power. The reasoning is that a bigger dredge has more interaction with its environment. Naturally, the environment gets more disturbed and turbidity levels should be higher for a bigger dredge. And the data was there to support this hypothesis. Smaller is better! Still, this does not undermine the initial results of the concept, as that was evaluated for turbidity per cubic meter. The bigger dredges also delivered more production. But when comparing dredges of the same concept might the smaller ones will perform better on turbidity. And this is in accordance with our experience. Every project where we’ve supplied these auger dredge units, the contractor and the client where surprised and happy about the achieved turbidity levels. Now, we know why: smaller is less turbidity.

The next step in performance might be reached by further decreasing the size of the dredge. However, the DOP is already as small as it is for a viable application on an excavator. The conclusion is to have an auger operating directly on the bottom: an unmanned submarine dredging machine!

Possible general arrangement of a robotic dredge submarine.
Possible general arrangement of a robotic dredge submarine.

This machine should navigate by itself and self-supporting. The wear parts of the auger should be exchanged by itself and solar panels can provide extra energy for extended missions. It has only a small hopper and discharge should also be done quick and automatically. An unmanned barge or even a dump truck trailer at the shore of the waterway can be replaced at longer intervals. Obstacles and other tricky spots can be alerted to a human supervisor for later intervention. One machine alone does not have an impressive production. The real power is in applying them in numbers. As we are standing on the brink of a revolution in robotics and artificial intelligence, this scenario may be not as farfetched as from your first impression. Imagine a whole school of these mechanical fishes cleaning up your waterway, while you sleep…

Working method of robotic dredge submarine (Credit: Judith Korver).
Working method of robotic dredge submarine (Credit: Judith Korver).


  1. WODCON, Damen
  2. New Year’s post 2019, Discover Dredging
  3. Ketelmeer project, Wikipedia
  4. Rapportage baggerproeven Ketelmeer. RIZA Rapport, 97.023, ISBN 9036950708
  5. DOP Pumps, 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


  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

Dredging Exhibits At The National Maritime Museum Gdansk

Overview of the National Maritime Museum in Gdansk, Poland

Currently I am in Gdansk, Poland. Last week I had a CEDA event1 and next week I am at the Hydro 2018 Conference and Exhibition2. On both events I will report later. My colleague Saskia den Herder wrote a teaser for you3. Now, here, I had the weekend for myself and what better to do, than be a tourist, visit a maritime museum and write a blog about it. So, I will report you about interesting dredging exhibits I discovered at the National Maritime Museum in Gdansk4.

The National Maritime Museum comprises three major venues: the museum building itself5, the ‘SS Sołdek’6 and the old city ‘Crane’7. All equally interesting in their own way. Buy a combined ticket and you get the ferry between them for free. As general maritime museums go, they mainly focus on the history of shipping, shipbuilding and the interaction with the development of the city or country. Gdansk in itself has a very long history in shipbuilding, as the country was well forested for providing the building material for ships. In modern times, one might have heard of the ‘Lenin Shipyard’8, the birthplace of the free labour union ‘Solidarity’, which brought Poland out of the socialist led economy. And of course, where there is water, there are ships and where there are ships, there is Damen9,10.

Horse powered scoop ladder dredge

Between the many models and pictures I found some about dredges indeed. This one seems to be a very first attempt at mechanical dredging. The power was provided by two real horses. There were some sort of scoops or blades drawn over a chute. The wooden blades excavated the soil from the bottom. Water was expelled through holes in the blades. The drained material could be loaded in barges for further transportation. Only after translation later on, I learned that in fact this was an example of a Dutch dredge!

Picture and model of a steam powered bucket ladder dredge

I did find a picture and a model of a locally build dredge. It employs a German steam engine and was built on an oak hull. It already featured the classic iron buckets on a ladder. The development of the working principle did not change that much. The dredged material could be delivered to barges at the aft end for further transport.

Grab dredge ‘Homar’

Finally I came across this model. It is a grab dredge ‘Homar’11, built in 1971 and operated by PRCiP Sp.z o.o. (Dredging & Underwater Works Co Ltd) here in Gdansk12. OK, I don’t want to brag, but it looked vaguely similar to the one we saw when we were on a site visit with the CEDA to the Port of Gdansk13. We had a splendid view over the harbour from the port control tower. And there I already noticed they were doing some dredging works in the entrance channel. But for all what we could see, it could also have been its sister ship ‘Świdrak’. And that concludes a nice round up of dredging discoveries for the weekend.

Overview of the entrance channel as seen from the port control tower. Dredging works indicated.


  1. CEDA-MIG Joint Symposium on Advances in Dredging Technology 2018
  2. HYDRO 2018
  3. Dam maintenance – deep dredging, Saskia den Herder
  4. National Maritime Museum in Gdansk
  5. Granaries on Ołowianka Island, NMM
  6. Sołdek, NMM
  7. Crane, NMM
  8. Gdanks Shipyard (Lenin Shipyard), Wikipedia
  9. Damen Engineering Gdansk, Damen
  10. Damen Marine Components, Damen
  11. Homar, Dredgepoint
  12. PRCiP
  13. Port of Gdańsk

See also