Key takeaways
- The highest value measurement is storage capacity against freeboard. How much room is left in a catch basin or storage pond before the next runoff event is a surface-against-surface calculation, and it is the number that is hardest to eyeball.
- Water hides the bottom. Photogrammetry and LiDAR both return the water surface, so the floor of a full basin comes from construction records rather than from the flight.
- Pen surface and drainage read clearly from the air. Low spots that hold water, pen slope that no longer drains the way it was built and the direction surface water actually travels are all visible in one capture.
- Manure stockpile volumes are a straightforward aerial measurement. The conversion from volume to tonnes needs a density from your own records, the same as any other stored material.
- A dated capture is the part a compliance file lacks. Most operations can describe their setup; few can show what the surface looked like on a specific date two years ago.
- Flying over livestock is a disturbance question, not a legal one. Altitude and flight line choices keep the aircraft away from pens with sensitive animals, and your own staff know which pens those are.
- Scope the capture at a sensible time of year. Late fall before freeze up and after the growing season gives the clearest pen surfaces and the most meaningful basin levels.
- The capture produces evidence, not a compliance determination. Reading it against your approval or registration is for you and your consultant.
A feedlot is a measurement problem wrapped in an operating business. The things worth measuring are the ones nobody can see properly from the ground: how much room is left in the storage, whether the pens still drain where they were built to drain, and what the surface actually looked like on a given date.
Storage capacity and freeboard is the number worth flying for
The single most useful output of an aerial capture on an intensive livestock operation is the capacity of the manure storage or catch basin against the level in it now. Freeboard is the vertical distance from the stored surface to the point where the structure would overtop, and it is the thing that decides whether the next heavy runoff event is a routine week or a problem.
Measuring it properly is a surface against surface calculation. The capture gives the top of what is in the basin and the crest geometry around it. What it cannot give is the floor, because water and liquid manure both read as a surface to any aerial sensor. The pulse does not come back from the bottom and the camera does not see through it. So the basin floor comes from the construction records or an as-built survey, and the capacity figure is only as good as that record.
Where the floor record is poor, the capture is still worth doing, because the crest elevations and the current level are measured directly. That gives freeboard, which is often the operating question, even where total capacity remains approximate.
Pens, slopes and where the water actually goes
Pen surfaces are built to a slope so that runoff moves toward collection rather than standing in the pen. After some years of cattle, scraping and reshaping, the as built slope and the real slope are frequently not the same thing, and the difference does not announce itself at eye level.
A surface model over the pen area shows it immediately. Low spots that hold water, pen slopes that have flattened or reversed, alley grades, and the actual path surface water takes across the yard all come out of one capture. So does the condition of the runoff control structures: berms, ditches, culvert inlets and the catch basin approach.
This is the part clients tend to find most immediately actionable, because the fix is usually a scraper and a day rather than a capital project, and knowing which three pens to do first is worth more than knowing that pens in general could be better.
Manure stockpiles and solid storage
Stockpiled solid manure measures like any other stored material. The capture produces a volume against a base surface, and the quality of the answer depends mostly on how well the base is defined. On a prepared pad the base is known and the volume is tight. On bare ground where the pile has been sitting and being worked for a season, the base is interpolated from the toe and the uncertainty goes up.
Converting that volume to tonnes needs a density figure, and that figure comes from your own records rather than from the survey. We report the measured volume, the density assumption used and the resulting tonnage as three separate things, so that if somebody later disputes the tonnage it is clear whether the argument is about the measurement or about the assumption.
Flying over livestock
The question we get asked most often, and the one that is easiest to deal with, is whether the aircraft upsets the animals. In practice the answer depends on altitude, on the aircraft, and on which pens.
A mapping flight sits well above the pens and is a distant noise rather than an overhead presence. The flight lines and altitude are planned so the aircraft is not hovering low over pens, and the launch and landing point goes somewhere away from stock. What we rely on is your staff telling us which pens need the widest berth: fresh arrivals, a hospital pen, calving, anything you would not walk a stranger through. That is a two minute conversation at the site orientation and it eliminates nearly all of the concern.
If something does cause a reaction, the flight stops. There is no measurement on a feedlot worth stressing stock over, and the capture can almost always be finished from a different line or on a different day.
The dated record, and why it is the durable value
Most operations can describe their setup accurately. Very few can show what the yard, the basin level and the runoff structures looked like on a specific date two years ago. That gap is what an aerial capture closes, and it is the thing that turns out to matter when a question arrives from a regulator, a neighbour, an insurer or a buyer.
For that record to be worth anything later it needs the ordinary discipline: a dated capture with the originals retained unedited, the datum and coordinate system written down, a stated accuracy with the method used to establish it, and consistent boundaries so the next capture is comparable to this one. A set of annual captures flown at the same time of year in the same datum is a defensible series. The same flights done inconsistently are five unrelated numbers.
On the Alberta regulatory side, the requirements that apply to a confined feeding operation sit in your own approval or registration, and they vary by operation rather than being uniform. We are not the right people to interpret them and we do not try to. What we can do is produce a measurement and an evidence trail in a form that your consultant can take straight into the file.
What an aerial capture cannot do here
It does not see below the surface, so it says nothing about liner condition, seepage, groundwater or soil nutrient levels. It does not see through water or liquid manure, so a full basin's floor is out of reach. It does not sample anything, so it is not a substitute for the soil and manure testing your nutrient management work depends on. It does not assess the structural integrity of a berm, only its geometry. And it does not determine whether you are in compliance with anything.
When to fly it
Late fall, after the growing season and before freeze up, is usually the best single window. Pen surfaces are at their most readable, vegetation around the structures has died back, and basin levels at that point in the year are the ones most worth knowing before winter. Spring after the melt is the other candidate, and it is the right choice if the question is specifically about how the yard handled the runoff. If this becomes an annual capture, pick one of those windows and keep it, because the comparison is the product.