NL
The Dotter project

The Dotter project

Nature Based Engineering

New technology improves the management of watercourses

Safer and cleaner, with more nature and lower costs

Flows in streams and other water courses such as locks and canals have to be kept unblocked so that rainwater is drained effectively and incoming water flows to the right place, preventing flooding and safeguarding water supplies. However, large amounts of vegetation can interfere with water flows. In general, water authorities in the Netherlands outsource mowing work on their watercourses and draw up specifications on the basis of visual and local inspections. But removing all vegetation has an adverse effect on nature, runs counter to the Dutch Flora and Fauna Act and doesn't help to achieve the objectives of the Water Framework Directive. In addition, a more targeted approach – that sometimes actually costs less – will achieve the same, or even better, results in terms of hydraulics and ecology.

The aim of the Dotter project, which began early this year, is to help water managers to implement mowing strategies. In that way, good incoming and outgoing flows are guaranteed without unnecessary ecological damage in and around the water. A full-spectrum camera mounted on a drone or boat is used to make complete images of watercourses. The camera uses the reflection of visible and invisible light to distinguish between vegetation and other elements such as open water and shoring.

The Dotter project

The images are then automatically interpreted, in part to determine the type and quantity of vegetation. The resulting data are used to calculate the flow resistance caused by vegetation and to identify ecological values. In time, information about sludge on the bed will also be included. All these data are linked to computer models for incoming and outgoing water flows, making it possible to map out the watercourses in a large area in a relatively short space of time. In addition, this is a tailored approach that makes it possible to take action in specific locations only.

The first field trials with the camera in the Netherlands were conducted at testing locations managed by the Rivierenland and Aa & Maas water authorities in the Linge and in the Lage Raam. The camera was tested in combination with an RPAS/drone last September in the River Experiment Centre (REC) at the South Korean Institute of Civil Engineering and Building Technology (KICT). Specific scenarios can be tested at full scale and in controlled ways at this large-scale outdoor facility. The technology should be in place in about a year from now and be used on a larger scale by the Dutch water authorities to manage watercourses.

The TKI dotter project gives us a new and accurate picture of the vegetation in waterways and streams. That allows us to do our mowing work more efficiently and to keep an eye on the ecology.
Sante Doringo
Team leader at Rivierenland water authority
These new measurement techniques give hydrologists, ecologists and landscape maintenance managers objective information about the status of vegetation in water courses throughout an area. This helps to identify the most effective approach to flood risk management and the ecological targets from the Water Framework Directive.
Ellis Penning
Deltares expert eco-engineering

For this project Deltares has collaborated with the following partners:

  • Waterschap Rivierenland
  • Waterschap Aa en Maas
  • KnowH2O
  • KICT Korea
  • Universiteit Twente
Ellis

Want to know more about this project?

Ellis Penning
Expert eco-engineering
  • +31 (0)88 33 58 468
  • Ellis.Penning@deltares.nl
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