Demo Waardassacker Project

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An overview of Demo Waardassacker.

This project is an example project, created by Jan Olsman at Waternet, in which the Waardassacker Polder's watersystem has been modeled for a year-round groundwater simulation. It was featured as one of the main presentations during the Community Of Practice 2021.

Case information

The Waardassacker polder is an area of the Netherlands which behaves mostly as a closed system. It features a single point of exit for any water within the polder, in the form of a pump which transfers water from the waterways inside the polder to the larger surrounding water basin. Water enters the area through seepage from the surrounding basin back into the polder's underground, or via rain. In addition, farmers have create very small culverts along the polder's surrounding levee, allowing small but significant totals of water to be let in from the surrounding basin as well, directly onto the surface waterways, for irrigation.

Model information

The intent of the model was to create a simulation to accurately mimic the flow of water in the water system during a year-round simulation, as compared to historic recorded measurements of flowthrough. This model could then be used to provide insight into:

  • The watersystem as a whole
  • The water-demand from the surrounding water basin into the polder (currently, and after the creation of drainage)
  • The effects of closing off (sections of) the "dirtier" surrounding water basin
  • Groundwater levels, as information which which to combat subsidence

To this end, a model has been created with all the usual hydraulic structures and hydrological features, with a number of notable points of attention:

  • The pump which moves water out of the polder is modeled as an outlet.
  • The culverts in the polder's levee are modeled as inlets.
  • Seepage was modeled with the usual seepage functionality, but the surrounding water basin was also included in the model to allow a more detailed groundwater flow along the edges of the polder.
  • Full groundwater simulation is active. Above the surface, the water body averaging mode is used.
  • Groundwater was initially loaded in, and then "initialized" in more detail by running a simulation, and using the results of that simulation as the new input file for the real simulation.


The project is directly derived from a customer's usage of the Tygron Platform, and is provided as-is. The purpose of its public availability is as an example for how end-user(s) have leveraged the technology to create a tool to suit their needs, so that the broader community has a comparative basis to create similar projects for their own purposes and specific use-cases.


Jan Olsman's presentation on the Water System in the Waarassacker Polder.