Hippos dredging in Delft!

Hippos dredging in Delft!

There are two ‘hippos’ in the Biesmolensloot in Delft. This artwork is part of an innovative piece of technology for sustainable water (soil) management which is being piloted in Delft.

Ships passing from the Schie are constantly churning up mud and sediment which accumulates in the Biesmolen.

How it works

The hippos are connected to a reservoir of the underlying Mudtrap, a specially designed under water container which collects the sludge. As a result of the flow in the ditch, mud particles are caught, and trapped by the hippos instead of flowing into the dike behind. As the tanks within the hippos fill, they, the hippos sink into the water, when their mouths are barely visible; it is time to empty them.

What does it mean?

Essentially the idea is that with these hippos less active dredging needs to take place, which results in improved water quality, less damage to fora and fauna and reduced expenses in dredging. The hippos are emptied with a .....thus eliminating the need for dredging barges.

This pilot programme is intended to test the application of the technology and establish whether similar systems can be adapted in the future. Furthermore, the sediment from the Mudtrap can be used, in combination with manure and plant material, to replenish areas where ground soil has dropped.

This pilot project falls under the Valorisation Programme Delta Technology & Water, which focuses on the testing and application of innovations.

Share this page


  • MH Waterzaken
  • Valorisatieprogramma
  • Gemeente Delft