Result type (Water Overlay)

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

Unique results

Each result type represents an aspect of the calculated water simulation, and is accompanied by its own legend. As can be seen in the list below, many result types are supported. The water 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 Water 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 Water Overlay to store additional result types. The advantage of using result child overlays are that for any given water 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.

Changing a result type

When the result type of the Water 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

Icon	Result type	Unit	Mode	Description
	WATER_STRESS	m (mm)¹	Maximum	The amount of water on the surface, similar to SURFACE_MAX_VALUE. Ignores water on water terrains unless it exceeds ALLOWED_WATER_INCREASE_M.
	SURFACE_LAST_DIRECTION	geo angle (0-360°)	Last	The direction in which water is flowing across the surface.
	SURFACE_AVG_DIRECTION	geo angle (0-360°)	Average	The direction in which water is flowing across the surface.
	SURFACE_DURATION	s (min)¹	Total	The amount of time the water depth on the surface exceeds SHOW_DURATION_FLOOD_LEVEL_M.
	SURFACE_ELEVATION	m + datum	Start	The rasterized version of the terrain height for use in the water overlay's calculations.
	SURFACE_FLOW	m³/m²	Total	The total amount of water which has flowed through a given location.
	SURFACE_LAST_DATUM	m + datum	Last	The water level on the surface, relative to datum.
	SURFACE_LAST_FLOW	m³/m²	Total	The last amount of water which has flowed through a given location.
	SURFACE_LAST_SPEED	m/s	Last	The (horizontal) speed of water flow.
	SURFACE_LAST_VALUE	m (mm)¹	Last	The amount of water on the surface.
	SURFACE_LAST_U	m/s	Last	The last speed of the water in the x-direction (u component of the surface equation).
	SURFACE_LAST_V	m/s	Last	The last speed of the water in the y-direction (v component of the surface equation).
	SURFACE_MAX_SPEED	m/s	Maximum	The (horizontal) speed of water flow.
	SURFACE_MAX_VALUE	m (mm)¹	Maximum	The amount of water on the surface.
	BUILDING_LAST_STORAGE	m (mm)¹	Last	The amount of water caught in building storage.
	FLOOD_ARRIVAL_TIME	s	Total	The time it takes for the specific grid cell to be flooded.
	FLOOD_RISE_RATE	m/hour	Total	The rate at which the water rose, counted from the start the water arrived to the moment it reached the flood threshold.
	LAST_RAIN	m (mm)¹	Last	The rain intensity at that point during the simulation.
	RAIN	m (mm)¹	total	The total amount of rainfall up to that point in the simulation.
	GROUND_LAST_STORAGE	m (mm)¹	Last	The (effective) amount of water in both the unsaturated and saturated zone.
	GROUND_LAST_VALUE	m (mm)¹	Last	The distance between the terrain surface and the groundwater level.
	GROUND_LAST_DIRECTION	geo angle (0-360°)	Last	The direction in which ground water is flowing under the surface.
	GROUND_FLOW	m³/m²	Total	The amount of water which has flowed through the ground horizontally for a given location.
	GROUND_MAX_STORAGE	m (mm)¹	Maximum	The highest (effective) amount of water in both the unsaturated and saturated zone during the simulation.
	GROUND_MAX_VALUE	m (mm)¹	Maximum	The distance between the terrain surface and the groundwater level.
	GROUND WATERTABLE	m + datum	Last	The groundwater level, relative to datum.
	GROUND_BOTTOM_FLOW	m	Last	The amount of water that has flown into the ground from deeper ground layers through the bottom boundary, raising the groundwater table.
	GROUND_LAST_UNSATURATED_STORAGE	m	Last	The amount of water in the unsaturated zone.
$Overlay icon water ground last unsaturated fraction.png$	GROUND_LAST_UNSATURATED_FRACTION	m	Last	The fraction of the total water storage capacity of the unsaturated zone that is filled with water.
	SEWER_LAST_VALUE	m (mm)¹	Last	The amount of water stored in the sewer.
	SEWER_MAX_VALUE	m (mm)¹	Maximum	The amount of water stored in the sewer.
	EVAPORATED	m (mm)¹	Total	The amount of water that has evaporated. The value is the sum of the quantities evaporated from the surface and the ground layers.
	LAST_EVAPORATED	m (mm)¹	Last	The amount of water that is evaporating at this moment.
	IMPACTED_BUILDINGS	Nominal	Maximum	Buildings impacted by excess water.
	TRACER_A	x/m²	Last	The amount of tracer A present. The value is the sum of the quantities on the surface, and in the underground.
	TRACER_B	x/m²	Last	The amount of tracer B present. The value is the sum of the quantities on the surface, and in the underground.
	TRACER_C	x/m²	Last	The amount of tracer C present. The value is the sum of the quantities on the surface, and in the underground.
	TRACER_D	x/m²	Last	The amount of tracer D present. The value is the sum of the quantities on the surface, and in the underground.
	BASE_TYPES	Nominal	Start	Categorization of the individual cells based on how they are processed by the water model, displaying which cells are considered to be specific features.
	DEBUG_UV	m/s	Last	The wave speed (u or v) of the 2D Saint-Venant system of either the x or y direction, depending on which one was the largest.
	DEBUG_UV_DIRECTION		Last	The dominant direction (u or v) of the largest wave speed of the 2D Saint-Venant system.
	DEBUG_AVG_AREAS	Nominal	Last	Shows each averaged surface water area, for insight into which waterways are or aren't connected and averaged together.
	DEBUG_WATERWAYS	Nominal	Last	Shows recorded disturbances in waterways, for insight into issues with extended shoreline reconstruction.
	SURFACE_DIFFERENCE	m (mm)¹	Last	The difference between the original water level and the water level of the last timeframe.
	GPU_OVERVIEW	Nominal	Maximum	Shows which GPU calculated which part of the overlay.

¹ the units between () are as displayed in the 3D client. If exported to GeoTiff the SI-convention is used: meters (m) and seconds (s).

Result types can differ in the kind of data they display, the layer (surface or underground) of which they display that information, and how that data is recorded. Different result types can monitor data in the following ways:

Start: The data is determined at the start of the simulation and does not change afterwards.
Last: The data is the latest value determined at the timestep the data is recorded. The values can increase and decrease between different timesteps. This mode is primarily used for monitoring progression.
Average: The data is the average value based on previous values up until the timestep the data is recorded.
Maximum: The data is the highest value determined up until the timestep the data is recorded. The values can only increase or stay the same, but will never decrease. This mode is primarily used to gain insight into impact; the most severe situation any point had to endure.
Total: The result of a running tally, counting the relevant data up until the timestep the data is recorded. The value can only increase or stay the same, but will never decrease. This mode is primarily used to gain insight into quantities rather than duration.

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:
1. The simulation has to run in full multiple times, causing a severe increase in calculation time.
2. When changes to the overlay's configuration have to be made those changes need to be made to all water overlays.
Result child overlays do not recalculate 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.