Drainage design by drones

A UAV helicopter (unmanned aerial vehicle) bouncing a pulsating laser beam off the Earth’s surface can produce a topographical field map with sub-one-inch accuracy.

The result is a highly precise drainage map.

The system is called LIDAR, standing for Light Detection and Ranging. Until recently, it was only affordable in the realm of geoscience researchers.

However, when costs fell LIDAR became within reach of agronomists and engineers in agriculture.

In the drainage business, the term “best performance” no longer means moving the greatest volume of dirt. Just the opposite, in fact.

In today’s world, “best performance” means moving the least amount of dirt to move the greatest volume of water. Moving dirt costs money. The object is to obtain drainage goals without moving extra soil.

This “best performance” depends on the quality of the topographical map, according to Steve Gillis, with Rocky Mountain Equipment in Moosomin, Sask.

Gillis is using LIDAR to develop drainage plans for prairie farmers. He works with Kevin Hruska at Bridgeview Manufacturing in applying Trimble LIDAR software that will enable Bridgeview’s Transformer ditcher operators to extract top performance from their machines.

“We use a LIDAR scanner mounted on a drone helicopter to get a laser scan of the surface, with sub one-inch accuracy,” explains Gillis.

“With the map, you go into a field with your Transformer and you know exactly where to go with your ditch and exactly what to do, down to the inch. As opposed to trying to figure it out once you’re out there in the field.”

Hruska concedes there are a lot of variables to manipulate if the operator expects to get the most out of his Transformer. That’s why Hruska and Gillis are working together on the topographic mapping project.

Gillis explains: “We take the LIDAR data and input that to your desktop computer. We can generate the actual lines you should follow. We put it into a Trimble 2050 display, using a program called WM-Drain.”

Trimble says their WM-Drain farm drainage solution is a concept-to-completion system that walks farmers through the survey, analysis, design, installation and mapping steps of surface and subsurface drainage. It ensures optimal 3D drain placement.

Gillis adds that the Rocky Mountain LIDAR he works with is not Trimble-specific. He can output the maps in any format, including Topcon and John Deere.

“WM-Drain allows you to follow the lines in the field. It raises and lowers the cutting edge of your Transformer. We’re not working on wing control yet. We’re just doing depth control right now. I have heard of a few ways to control the wings, but I haven’t actually seen them.

“On Case, New Holland and John Deere, you can only automate the first and the third hydraulics, so you would not be able to automate the centre and both wings unless you had some way to split the signal. It’s up to the operator to control the wings manually, and that’s a matter of experience.

“Most of the guys I’ve been working with take their wings and fold them in a little bit. They use the Transformer flat blade to do a pass or two and make nice smooth ditch bottom, then they’ll pull the wings up and use them for feathering and contouring the edges. You don’t use the wings too much while you’re actually cutting. So I don’t think you’d gain much by automating the wings.

“Flat country is a different story. You’d use your wings in potato and vegetable country and flat land where you’re just levelling, trimming down little high spots and filling in small depressions.”

Gillis says the Pulldozer Transformer can serve the same purpose as a scraper to some degree. It’s a matter of filling the blade and pulling the dirt along to the destination.

Using the in-cab display, the operator manually sets the blade depth so it’s not picking up new dirt and it’s not spilling over the dirt already captured.

Although there are other systems capable of running the Pulldozer Transformer, Gillis says LIDAR is the most accurate. LIDAR for agriculture is new. He says that until now, you’d be looking at a $20,000 to $30,000 mobilization fee up front if you wanted a LIDAR field survey.

“The price point has been too high for agriculture. We’ve been able to lower the cost and make it viable for farmers because our in-house geomatics team also works in gas and oil exploration, construction, natural resources, defense and those related fields.

“Most other people would probably buy one of the commercially available drones, then figure out how to install their payload. Our team did the opposite. They looked at what was available and decided they needed something better. So they took the LIDAR package and designed their own helicopter around that package.

“It’s totally designed and built in-house. It’s a large, very capable drone that carries a 25-pound payload, which we need to carry the LIDAR equipment. It’s about eight feet long, weighs about 75 pounds and has a two-stroke gas engine. We can take it out to a farm and produce highly accurate elevation maps for $6 per acre. That gives you the map, the data and a drainage analysis.”

From that point, the client can proceed on his own or Rocky Mountain can continue in building the prescription map. If the farmer wants to do it on his own, the necessary desktop software package costs US$3,000.

Gillis adds that his team doesn’t need a 10,000-acre project to mobilize the system.

The $6 cost holds, even if it’s just for a couple quarters.

If there are flooded fields because of mid-summer rain, Gillis and his crew can still do a LIDAR survey of the target while water is at the peak using a special drone boat equipped with a bathymetric sonar system, which uses green wavelengths to penetrate the water surface.

The bathymetric system lets them chart the floor of the potholes and sloughs to document water depth and calculate water volume. Having real time data on acre-feet of water volume while field is still flooded can simplify the process of building a drainage plan.

Gillis says other elevation measurement systems use photogrammity, a process that takes hundreds of aerial photos and stitches them together to build a 3D image.

Photogrammity is less accurate than LIDAR and cannot penetrate a crop canopy, which LIDAR can do. If the LIDAR laser beam can shoot through the leaves and find any soil, it can create a topographic map, meaning it can be used in more conditions and in more seasons of the year.

However, the laser does not shoot through snow.

For more information, contact Steve Gillis at 306-434-8509.

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