Land & Water / Grimes County Ranch / June 2026

Grimes County Ranch

Terrain and constraint analysis to help decide where to build on a flood-shaped tract.

A plan-scale set of land and water exhibits, built from drone-flown LiDAR: a one-foot-contour terrain model, derived slope and flow-accumulation, a drainage and flood sheet, and a siting composite.

Flood frequency modeled on the real terrain: the ten-, hundred-, and five-hundred-year extents against the Navasota. Grimes County, Texas.

The tract

A multi-tract ranch in Grimes County, Texas. The owner needed to know where the dry, stable ground actually was before he committed to a building site. From eye level the upland and the bottomland blur together. The contours and the water don’t.

What we flew and modeled

We flew the property with drone LiDAR and built the terrain out to one-foot contours, indexed every five. From that surface we derived slope, flow accumulation, and a flow-frequency model of how water gathers and moves across the tract through the ten- to hundred-year events.

Topographic plan of the Grimes County tract: one-foot hypsometric-tinted contours showing the eastern upland rising above the bottomland. — Topographic plan: one-foot contours across the property. Grimes County, Texas.

Reading the ground

The model splits the property cleanly. The eastern upland is the high, stable ground, and it stays clear of the modeled flood extent. The bottomland is flat and inviting, and it floods. We drew the line between the two and put acreage to each, so the tradeoff is a number instead of an argument.

A CTG drainage and flood analysis sheet for the Grimes County tract, showing the modeled flood extent in blue over the terrain model (anonymized). — Drainage and flood: the modeled flood extent and flow network over the property. Grimes County, Texas.

Slope analysis of the Grimes County tract, classed by grade, with the eastern upland primary build ground identified. — Slope analysis: build-class slope across the tract, with the eastern upland build ground called out.

The exhibits

The deliverable is a set of plan-scale exhibits: a drainage and flood sheet with the modeled flood extent and flow network, a slope and contour base, and a build-ground summary table. All of it made to be read across a table by the people making the call.

What it informed

The owner walked away with the buildable footprint identified and quantified, and a clear picture of what to keep clear of. The exhibits informed the siting decision. They didn’t make a regulatory one, and they were never meant to.

Siting composite for the Grimes County tract, overlaying contours, drainage, and slope to show the buildable upland footprint. — Siting composite: the terrain, drainage, and slope layers resolved into the buildable footprint.

Get in touch: jacob@caudelltg.com