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Consultants identify 17 flood problem areas in Waller County master drainage study
Summary
LJA consultants presented countywide hydraulic modeling that identified 17 priority flood problem areas and recommended steps to develop projects for the state flood plan and grant scoring. The study maps structure and roadway impacts and proposes next-step causation analysis and solution development.
Consultants from LJA presented results of a countywide master drainage study that modeled existing conditions across six watersheds and produced a prioritized list of 17 problem areas for further analysis and potential project development.
William (Will) Conlon, senior project manager for LJA, said the team ran detailed two-dimensional rain-on-mesh models and overlaid inundation results with structures, roads and land values to identify locations where flooding repeatedly impacts property and transportation. "We analyzed multiple storm events," Conlon said, noting the team used a threshold of 6 inches of ponding to mark roadways as impassable and modeled finished-floor assumptions for structures (one foot above ground for most structures, three feet for mobile homes).
Daniel Dodson, LJA assistant project manager, reviewed watershed-specific results: Walnut/Spring Creek showed dozens of structures impacted in the 10- and 100-year events; Beason/New Year Creek was relatively less impacted; Clear Creek and Little Cypress/Cypress Creek showed concentrated impacts in Hempstead and southeast Prairie View; and Bessie/Mill Creek (including Brookshire) was the most broadly affected area. The consultants said their analysis excluded Brazos River peak flow in some overlays (they plan a parallel Brazos-focused analysis) and that some areas overlap with the Brookshire-Katy Drainage District studies.
LJA said next steps are a detailed causation analysis of each problem area (undersized culverts, insufficient channel depth, low-lying depressions, or detention shortfalls), development of alternative solutions (channel improvements, detention basins, culvert upsizing) and packaging candidate projects for inclusion in the Texas state flood plan to make them eligible for Flood Infrastructure Fund grants. "We identified the problem areas and our next step is alternative analysis and refinement so these can be scored in the state flood plan," Conlon told the court.
County staff and commissioners discussed the need for right-of-way authority and potential formation of a drainage district to secure continuous control of channels and implement large-scale improvements. Conlon emphasized that channel improvements must be paired with detention or flow restrictors to avoid moving flood impacts downstream to neighboring counties.
The court received the presentation for information; consultants offered to provide technical memos and hold follow-up workshops focused on specific problem areas as commissioners and staff prioritize projects for funding applications.
