Water quality

3Di can be used in water quality assessments. More specifically, you can introduce concentrations of substances to the simulation, and compute how these substances spread through the water system due to advective forces and (numerical) diffusion. See Water quality.

Running water quality simulations

Simulations with water quality can be run with any 3Di model. You do not need to make any changes to the model schematisation.

It involves the following steps:

  • Define one or more substances that you want to use in the simulation, e.g. “Benzene hexachloride”, “Biological Oxygen Demand (BOD)”, or “Contaminant”.

  • If the simulation includes initial water (in the 1D and/or 2D domain), you may set an initial concentration of the substance(s) you have defined in the initial water.

  • If the simulation includes forcings, such as rain, boundary conditions, or laterals, you may add a concentration of the substance(s) you have defined to these forcings. Each forcing can contain concentrations of multiple substances at the same time.

    Note

    The way substance concentrations are defined, mirrors the way that the initials or forcings are defined. I.e., 2D initial water levels are supplied as a raster, so 2D initial substance concentrations are also supplied as a raster; substance concentrations in time series rain is also provided as a time series; et cetera.

  • Run the simulation in the same way as you are used to

Water quality simulations in the 3Di Modeller Interface

The water quality module can be used in simulations started from the 3Di Modeller Interface.

At the moment, the simulation wizard supports adding substances to laterals only.

Follow the same workflow as for starting any other simulation, with the following additional steps.

.# On the scenario options page that is shown before the simulation wizard starts, check the box Include substances .# After having filled in the Name and Duration pages, the Substances page lets you define the substances that you want to use in the simulation. .# On the Laterals page, upload a CSV for 1D or 2D laterals and a CSV with time series of concentrations for each of the substances that you want to add to your simulations. .# Go through the rest of the steps of the simulation wizard to start the simulation

Water quality simulations using the 3Di API

If you want to use water quality features that are not yet supported in the 3Di Modeller Interface, such as substance decay or adding substance concentrations to forcings other than laterals, you can use the 3Di Models & Simulations API directly. Contact the Service desk for example scripts that fit your specific purpose.

Viewing and analysing water quality results

The results of a water quality simulation are the concentrations of each substance at each node, for each output time step. These values are written to a separate NetCDF file.

A summary of the water quality calculations is available in the simulation logging. This log file includes a substance summary, similar to the flow summary.

At the moment, the Time series plotter is the 3Di Results Analysis tool with support for the 3Di water quality module.

.# Download the simulation results via the 3Di Models & Simulations panel. The Water quality results 3Di file will also be downloaded. .# Load the results using the 3Di Results Manager .# Open the Time series plotter .# Add one or more nodes to the plot .# In the Variable dropdown menu in the Time series plotter, select the substance you want to see the concentration for.

For other visualisations of substance concentrations, e.g. as a map of the substance concentrations at a specific moment in time, or an animation of such maps, use 3Di Results API (threedigrid). Contact the Service desk for example scripts that fit your specific purpose.