Drone LiDAR Surveys in Tennessee

Tennessee already has LiDAR. That's the first thing to understand about a drone LiDAR survey here, because it's the first thing an engineer in Nashville or Knoxville will bring up.

The state's QL2 collection is 100 percent complete, delivered through the USGS 3D Elevation Program at a minimum of two points per square meter, vertical accuracy of 10 cm or better, and a 1-meter DEM — free to download from the Tennessee Elevation/LiDAR Program. Davidson County got a denser QL1 flight in 2022. For a watershed study, a floodplain model, or a first look at a 2,000-acre tract, that data is excellent and you should use it.

Current coverage, vintage and downloads: USGS — 3DEP Supporting Tennessee's Economy · lidar.tn.gov

Statewide acquisition began in 2015 and was flown in phases, so the vintage of the tile under your site varies by county. Check it before you design off it.

What it isn't is a project survey. Two points per square meter is a point every couple of feet on open ground, and far fewer where canopy ate the pulses. It was flown years ago, before the pad got cut, before the sinkhole opened, before the levee blew out. A project-scale drone LiDAR flight puts hundreds of points per square meter on the ground, on the date you pick, tied to your control. Those are two different products, and most of the Tennessee jobs we fly start with someone who has already pulled the state tile and found it isn't enough.

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Karst: the Tennessee-specific reason to fly dense

The Central Basin and the Highland Rim around it sit on limestone. So does the Ridge and Valley from Chattanooga to Bristol. That means sinkholes, sinking streams, and closed depressions that don't show up on a 1-meter DEM until they're big enough to swallow a truck.

Tennessee's permanent stormwater manual carries a karst appendix for exactly this reason. It calls for identifying existing sinkholes before design, recording them on the plat, running borings under any centralized stormwater facility, and pushing toward distributed small practices instead of one big pond that might open the ground under itself. Every one of those steps starts with knowing where the depressions actually are.

A dense bare-earth model is the best available tool for finding them. A shallow closed depression eight feet across and ten inches deep is invisible on a contour map, invisible in tall fescue, and obvious in a hillshade built from a few hundred ground returns per square meter. USGS's own karst depression mapping for Tennessee notes the coarse-DEM method can't distinguish sinkholes from man-made or natural depressions — that's a resolution problem, and density is how you solve it. The drone surface doesn't tell you what's underneath. It tells your geotech where to bore.

This is also why the Nashville-area development boom keeps our phone ringing. Rutherford, Williamson, Wilson, Sumner — site grading and stormwater design on rolling limestone ground, with a stormwater reviewer who has read that appendix. Fly it once, dense, before the civil set goes out.

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The Plateau: steep timber and old mines

The Cumberland Plateau is a different problem. Flat-topped, deeply cut, and covered in the largest contiguous block of forest in the state. Anything you need to see on a Plateau slope is under hardwood.

Two kinds of work show up there. Timber and access — haul road layout, harvest-unit boundaries against real slope, stream buffers set on the actual channel rather than a blue line from 1970. And coal reclamation. TDEC's Land Reclamation Section runs the state's Abandoned Mine Land program — highwalls, subsidence, refuse piles, landslides — with IIJA money now behind it. Reclamation design needs existing-condition surfaces on ground that is steep, wooded, and unsafe to walk with a rod. Volumes on a highwall backfill are where a dense surface earns its keep.

The gorges make line-of-sight the real work. Flyable, but we plan it before we quote it.

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West Tennessee: bottoms, levees, and ducks

West of the Tennessee River the state flattens into the Hatchie, Forked Deer, Obion, and Mississippi bottoms. This is levee country and duck country, and it's the ground we know best from home in Alabama.

A dense bare-earth surface under bottomland hardwood is what a levee survey is built from: real existing terrain across the whole corridor, cut and fill volumes before anyone moves dirt, as-built verification after. And the same model, used differently, is what flooded timber modeling runs on — pick a pool elevation and see the acres and depths you'd actually get before the levee exists.

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Why LiDAR and not photogrammetry

A camera sees the top of whatever's there. Over a soybean field in Dyer County, photogrammetry is excellent and cheaper. Over a Plateau slope in July, it produces a beautiful model of the canopy and nothing about the dirt.

LiDAR fires enough pulses that some find gaps and return off the ground. Those returns get classified and used to build the bare-earth surface. That's the whole trick, and it's why LiDAR is the right tool for anything wooded, and photogrammetry is often the right tool for anything that isn't. We run both, and we'll tell you which one your site needs. The full drone LiDAR workflow is the same on every job; only the site changes.

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What we deliver

Whatever your engineer works in. Classified LAS or LAZ point cloud, bare-earth DTM, DSM, contours at any interval, orthomosaic, volumetrics, DWG/DXF, GeoTIFF, shapefile, and PDF sheets. Tennessee State Plane or whatever coordinate system the job specifies.

Everything is processed in-house. If the engineer needs breaklines pulled a specific way or a particular contour interval, that's a conversation, not a change order. For active sites, the same flight also documents construction progress.

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Accuracy — the honest version

We set up an RTK base station on every mapping mission. When the job calls for it, we set ground control points and independent checkshots so the surface is proven against something, not just reported.

The tightest vertical accuracy comes on open ground with proper control, and we report the checkshot numbers so your engineer can see what the surface actually holds. Under heavy canopy it degrades, because fewer pulses reach the ground and the bare-earth surface is built from a thinner sample. Dense cedar on the Basin glades and rhododendron in the Plateau gorges are the hard cases. That's physics, not settings.

We'll tell you what your site and budget will support before we fly.

Paragon is not a licensed surveying firm. We collect and process aerial data. Boundary surveys, plats, and any sealed document are work for a Tennessee-licensed RLS or PE — we provide the surface they design from and certify against.

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Who calls us in Tennessee

Civil engineers designing grading and stormwater on karst. Land surveyors who need dense topo under trees without walking it. Developers and site contractors who want volumes they can bid against. Foresters and timber companies on the Plateau. Duck clubs and landowners in the western bottoms — many of whom already know us from drone deer surveys. Mining and reclamation contractors working AML sites.

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Getting on the schedule

We're based in Tuscaloosa and travel across Tennessee with our own pilots, our own fleet, a 24-ft mobile command trailer, and a UTV for getting control set where a truck won't go. FAA Part 107, insured, and 53,000-plus acres of LiDAR, mapping, and site work flown in the last 12 months alone — more acres with LiDAR drones than just about any company in the South.

Send a boundary — KML, shapefile, or an onX link — and a sentence about what the engineer needs. We'll come back with a plan and a price.

Call or text 205.394.6256.

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Where to verify

Statewide LiDAR coverage and specs: USGS 3DEP Tennessee fact sheet · Data downloads: Tennessee Elevation/LiDAR Program · Karst stormwater design: TN Permanent Stormwater Manual, Appendix B · Mine reclamation: TDEC Abandoned Mine Land Program