Result type (Watershed Overlay)

The Watershed Module of a Watershed Overlay performs complex calculations and multiple types of results can be provided.

Unique results

Each result type represents an aspect of the calculated watershed simulation, and is accompanied by its own legend. As can be seen in the list below, many result types are supported. The watershed module can record more than one result type. However, since not all result types can be stored at the same time, only the selected ones are recorded. These results will be stored in individual overlays.

There is always one general Watershed Overlay. The configuration for the calculation is only defined in this overlay, which makes it easier to verify and configure the used simulation parameters. Result child overlays can be added to this Watershed Overlay to store additional result types. The advantage of using result child overlays are that for any given watershed overlay, the calculation of the overlay only occurs once, rather than multiple times equal to the amount of desired result types.

It is currently only possible to add result child overlays via the configuration wizard, in the step regarding output overlays.

Naturally, the results can be seen visually. They can also be inspected in more detail, and also exported as a GeoTiff.

Changing a result type

When the result type of the Watershed Overlay or any of its children, is changed, the legend is updated automatically. However, the data for this new result type must still be calculated. This may result in the visual output of the overlay changing, because the unchanged data is displayed with a new legend. When changing the result types, it is recommended to force a recalculation of the overlay before inspecting the results.

List of Result Types

Result type	Unit	Description
BASE_TYPES	Nominal	Categorization of the individual cells based on how they are processed by the watershed model, displaying which cells are considered to be specific features.
DIRECTION	geo angle (0-360°)	The direction to which rain water would flow.
DISCHARGE_AREAS	Integer	The initial Discharge Areas and propagated to water cells by neighbors and culvert-connections.
WATERSHEDS	Integer	The integer ID of the calculated watershed. NO_DATA if no watershed area was calculated for that particular cell.

Notes

Although it is possible to duplicate the overlay, and set the copy of the overlay to a different result type, we strongly advice to use child overlays instead. Downsides of the duplication approach are:

the simulation has to run in full multiple times, causing a severe increase in calculation time.
when changes to the overlay's configuration have to be made those changes need to be made to all water overlays.

Result child overlays are not (re)calculated if either they or their parent is set to inactive.
If a calculation overlay is removed, all result child overlays of that overlay are removed as well. Separate overlays set as child overlays (such as input overlays) of the overlay will not be removed.