Stormwater Modeling Resources
Locally relevant tools for LID detention, drawdown, and routing in the Houston region.
Accurate hydrologic modeling is the backbone of any successful Low Impact Development (LID) project — especially when navigating the detention and release-rate expectations common across Harris County and the City of Houston.
To assist civil engineers, designers, and hydrologists, HLWSF provides access to practical tools, locally relevant parameters, and standards-aligned details that can be adapted to your project conditions.
Drawdown Calculators
Tools to verify that bioretention media, underdrains, and permeable pavement sub-bases meet typical 48–72 hour drawdown targets often associated with Type D clay soils and low-permeability subgrades.
Rainfall Distribution Models
Updated Atlas 14 rainfall datasets pre-formatted for common modeling workflows, including HEC-HMS and EPA SWMM, with hyetographs and storm distributions that reduce formatting time and input errors.
Standard CAD Cross-Sections
Downloadable .DWG details for commonly specified green infrastructure systems, designed to speed up drafting and help standardize typical sections across plan sets.
How to Use These Resources
- Confirm your jurisdictional criteria (detention volume, release rate, drawdown target).
- Select the appropriate tool (calculator, model input, or CAD detail).
- Adjust parameters for your site (soil infiltration rate, media specs, storage depth).
- Document assumptions in your drainage report and planset notes.
This increases clarity and reduces misuse.
Important Notes
These resources are provided as educational tools and starting templates. Projects must be designed and sealed by a licensed professional and verified against current local criteria, manufacturer specifications, and site-specific geotechnical data.
Have a Resource to Share?
We welcome locally relevant spreadsheets, calibrated parameters, and standard details that help improve stormwater modeling consistency across the Houston-Galveston region.