Liberty County gets detailed update on multi‑year master drainage plan; LIDAR, monuments and models to guide projects

William Conlon, senior project manager at LJ Engineering, told the Liberty County Commissioners Court on Oct. 14 that a multi‑year master drainage plan is under way that relies on new 2024 LIDAR, extensive field survey work and multiple hydraulic modelling approaches.

Conlon said most of the past nine to 10 months were spent on data collection and verification, and that the team has consolidated a countywide dataset that includes about 1,300 square miles of delineated drainage areas, roughly 800 subbasins and about 1,700 miles of channel. "We've now constructed about 280 monuments," Conlon said, describing survey rods installed at roughly one‑mile spacing across the county and a web portal that documents each monument's coordinates and elevations.

Why it matters: the combined dataset will feed two model types used by flood practitioners — what Conlon called the applied‑hydrology approach (river‑centric, FEMA‑style mapping) and a higher‑resolution "rain‑on‑mesh" surface approach that simulates runoff across terrain before it reaches channels. That detail is intended to reveal localized urban…