How to model drainage (Water Overlay)

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When using the Water Overlay to calculate groundwater model (Water Overlay) situations, the presence of drainages can have a strong impact on the results. Currently, drainages are not an available hydraulic structure. Instead, the effects of drainages can be approximated using Aquifers, configured with a low resistance and set to the height of the drainages.

Manually adding a drainage

Editor → Current Situation (Ribbon tab) → Areas (Ribbon bar)

Note that these steps assume the Overlay Keys are set to the default Attributes.

How to manually create a drainage-approximating aquifer:
  1. Add a new Area to the Project.
  2. Draw the Area in the 3D World in the location where the drainages are.
  3. Add an AQUIFER_KD Attribute to the Area with value 1000.
  4. Add an AQUIFER_HEIGHT Attribute to the Area, with the height of the drainages relative to datum as value.

Preparing and importing drainage data

Editor → Current Situation (Ribbon tab) → Overlays (Ribbon bar) → your Water Overlay (Left panel) → Configuration Wizard (Right panel)
How to prepare and load in drainage data:
  1. Ensure your geographic data set has polygons indicating the locations of drainages.
  2. Ensure that the data has attributes indicating an (excessively) high flow-through value.
  3. Ensure that the data has attributes indicating at what height relative to datum the drainages are situated.
  4. Export the data as GeoJSON.
  5. Open the Water Overlay Wizard, and continue to the step for aquifers.
  6. Opt to import new data, and import your drainages file.

Notes

  • Aquifers function across their entire polygon. In real life, drainages are discrete tubes where water can actually flow freely. In between tubes, water actually still only flows with the speed the underground allows. To model this most accurately, the individual drainage tubes should be represented by individual polygons. However, although some detail may be lost by drawing the drainages as a complete and uninterrupted area, functionally the effect of sped up underground flow is still achieved.
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