How to find where stormwater will pool on your site

Use the Closed Depressions Report to see the low areas where stormwater will collect after rain — across the whole site, color-coded by depth.

Written by Raymond Fuorry
Updated over a week ago

What the Closed Depressions Report shows

The Closed Depressions Report (CDR) visualizes the low areas on your site's elevation model — a DEM, or digital elevation model, built from the drone scan — that have no outlet for water to drain, and identifies how deep water could stand in each one. If heavy rain comes, these are the areas where stormwater will most likely accumulate.

The report shows the maximum possible water level for each depression, and it accounts for the locations of storm inlets on your site — a depression with a working inlet inside it won't be filled in the analysis.

Availability: the Closed Depressions Report is available as a Gold add-on and is included with Platinum.

Why grading and drainage teams use it

Stormwater pooling in the wrong place creates problems at every stage of a project, and the report exists to catch those spots before the rain does:

• During earthwork: SWPPP (Stormwater Pollution Prevention Plan) violations, downed silt fences with dirt washing away, and damaged materials.

• On finished lots: slopes that don't meet requirements, puddles on building pads or future driveways, and grading destroyed by utility or foundation digging.

• HOA slope requirements: homeowners-association slope standards must be adhered to and can change — a site-wide drainage picture is the fastest way to check where you stand.

How to use the report

The Closed Depressions Report works best as the first look that tells you where to dig deeper:

1. Scan the whole site visually for areas at risk of stormwater flooding — the color-coded depths make the risky spots obvious at a glance.

2. Investigate the flagged zones with the measurement tools: Surface Comparison, Cross-Section, and Distance & Slope confirm what the grading actually does there.

3. Record properly graded areas — for example, document that roads were graded correctly before utility crews excavate trenches, so there's a dated record if the grading is disturbed.

What the report needs from you (setup)

To produce an accurate Closed Depressions Report, TraceAir needs two things from your team:

1. Your drainage layout. The analysis uses the locations of storm inlets (usually along road borders, sometimes between lots) and overflow inlets in ponds. Most customers already have a CAD file with the drainage system layout — send it to your Customer Success contact. Without inlet locations, the analysis fills every depression, including ones that drain through an inlet, so the picture will overstate your risk.

2. Your schedule. Reports are generated per scan, so tell us whether you want the report on every scan or only for specific dates (for example, before a forecast storm or at a grading milestone).

What the report does not account for

The Closed Depressions Report is a surface analysis, and it's important to know its limits: it does not account for soil properties (how fast water infiltrates) or for the capacity of the drainage system — only for the shape of the ground and the locations of inlets. Treat it as a reliable "where would water sit" map, not a hydrology study.

Frequently asked questions

Does the report account for storm inlets?

Yes — the Closed Depressions Report uses the storm-inlet and overflow-inlet locations from your drainage CAD file, and depressions that contain a working inlet are not filled in the analysis. That's why providing the drainage layout matters: without it, every low area shows as a risk.

Does the report account for soil type or pipe capacity?

No — the analysis does not use soil properties or the capacity of the drainage system. It shows where water would stand based on the shape of the ground and inlet locations, at the maximum possible level.

Can I get the report on every scan?

Yes, the Closed Depressions Report can be generated for every scan or only for specific dates — let your Customer Success contact know the schedule you want when you set it up.

What do I need to buy to get it?

The Closed Depressions Report is available as a paid add-on for Gold sites and is included at no additional cost with Platinum.