How to read your report

These points apply to every rain flood screening. Your report and your result page add what is specific to your address.

What was modelled

The depth is water standing on the ground. The model knows no door, window-well, garage or basement levels, no backwater valves and no sewer connections, so it cannot say whether water gets inside.
Rain falling on roofs is assumed to leave through gutters and downspouts into the sewer, so it does not reach the ground in the model. Where downspouts empty onto the lot, the ground next to them can get wetter than shown.
This is a model estimate, with no allowance for climate change. The storm is one gauge's statistics, or a fixed design storm where no gauge applies; your report says which. It is a design storm, not an observed event, so its timing is illustrative.
Where the storm comes from a gauge, this is what its return period means. A 100-year storm has about a 1-in-100 chance of being equalled or exceeded in any given year. The rain is applied as a design storm shape that peaks partway through, not as steady drizzle.
Only rain falling within about 400 m is modelled. A property below a long slope may receive more water than shown.
The terrain is NRCan's 1 m HRDEM, resampled to a 2 m simulation grid. Construction or grading after the LiDAR survey is not reflected. Building outlines are from OpenStreetMap and are treated as obstacles to the flow.

Not modelled: lot drainage (grading, swales, drains), sewer backup, ice jams, storm surge, and water arriving from a river or a lake.
Where the structures inventory records a culverted road crossing, it is lowered to a partly blocked opening rather than solved hydraulically. A crossing that is actually clear will pond less than shown; one that is blocked or undersized will pond more.

Where Ville de Montréal inlet data are used, this is what applies. Storm drains are modelled only as a capped removal rate on ground served by a municipal catch basin; the pipe network itself is not modelled.
Elsewhere, storm drains are not modelled: the depth is an upper bound wherever a working drainage network would carry water away.

Validation status: with Ville de Montréal inlet data, the model has not been validated against observed floods.
Validation status: for runs that credit no storm-drain capture, the model has not been validated against observed floods.

The grade comes from a 0 to 100 score of how complete and well sourced the model's input data are. A: 92.5 or more. B: 75 to under 92.5. C: 55 to under 75. D: under 55, or terrain or vertical datum not verified (no report is issued). It describes the input data, not how close the depth is to a real flood.

For information only. This is a screening, not a hydraulic study, an insurance assessment or an official flood map.