Viewing Results

When a Run reaches Complete, Hydrata adds its result layers to your project map automatically. This page explains where those layers appear, what they show, how to style them, and how to compare the results of two Scenarios.

Watching a Run finish

Select your Scenario in the Scenarios panel and open its Run tab. The status pill steps through the Run lifecycle:

Created > Building... > Queued > Computing > Processing results... > Complete

While the Run is Computing, the status card shows a progress percentage and an estimated time remaining. Processing results... means the simulation itself has finished and Hydrata is converting the outputs into map layers. If something goes wrong the pill shows Error with the failure message, and a Retry button appears.

Where result layers appear

The moment a Run completes, Hydrata renders its outputs onto the map and lists them in the Results menu (open it with the View Results button that appears on the Scenarios panel, or from the left toolbar). The project layers panel keeps showing your input layers (terrain, mesh, boundary, inflow, friction); the Run's outputs live in the Results menu, grouped by quantity:

Layer	Group	What it shows	Units
Scenario name Depth Max	Depth	Maximum water depth reached at each point	metres
Scenario name Velocity Max	Velocity	Maximum flow speed reached at each point	m/s
Scenario name Momentum Max	Momentum	Maximum depth-integrated velocity (depth multiplied by velocity), a common flood-hazard indicator	m²/s

Each layer is named after the Scenario that produced it, so results from different Scenarios in the same project stay distinguishable.

These are maximum envelopes, not snapshots

Each cell shows the highest value it reached at any time during the simulation. Different cells can peak at different times, so a maximum layer is not a picture of one moment in the flood. It answers "how bad did it get here", which is usually the question that matters for planning and design.

See ANUGA Concepts for the physical definitions of depth, velocity, stage, and momentum.

Maximum layers vs the full time series

The map shows the maximum envelope for each quantity. The full time history is preserved too: ANUGA writes the complete time series to an SWW file, and Hydrata also generates one GeoTIFF per output timestep for each quantity (including stage, the water surface elevation). These files are not published as map layers, but they are all kept in the downloadable result files. See Exporting Results.

Reading the map

• Dry ground is transparent. Cells the water never reached have no value, so the terrain and basemap show through.
• Very shallow water is hidden by default. The depth style fades in from about 0.1 m, so films of water a few centimetres deep do not clutter the map.
• Default colour ramps: depth shades from pale blue-green to dark blue across 0 to 6 m; velocity runs 0 to 6 m/s; momentum runs 0 to 5 m²/s. Expand a layer in the layers panel to see its legend.

Styling and opacity

Result layers behave like any other layer on the map:

• Toggle visibility with the checkbox next to the layer name. If you have several completed Scenarios, turn on one result layer at a time so you are not reading two floods stacked on top of each other.
• Adjust transparency in the layer settings to see the terrain, structures, or aerial imagery underneath the flood extent.

Comparing two Scenarios

The most common results question is "what changed": existing versus proposed conditions, before versus after a mitigation work, one rainfall event versus another. Hydrata computes the difference between two Scenarios' results and publishes it as new map layers.

Both Scenarios need at least one completed Run, and you need contributor access to the project.

1. In the Scenarios panel header, click Compare. A checkbox appears beside each Scenario.
2. Tick your baseline Scenario first (for example, existing conditions).
3. Tick the changed Scenario second (for example, the proposed design).
4. Click Run in the panel header (it appears once exactly two Scenarios are selected).

The comparison runs on cloud compute and takes a few minutes. When it finishes, three difference layers appear under Results:

• Comparison: Depth
• Comparison: Velocity
• Comparison: Momentum

Each comparison layer subtracts the first selected Scenario from the second, using each Scenario's most recent Run. Positive values mean the second Scenario produced deeper or faster water at that point; negative values mean it reduced flooding there. Selection order matters: pick the baseline first so that "positive equals increase" reads naturally.

Note

The default depth-difference style hides changes smaller than about 0.05 m, so areas the change did not meaningfully affect stay transparent and the real impacts stand out.