Workflow (end-to-end)

This is the recommended high-level sequence for typical designs.

1) Prepare catchment inputs

• Derive catchment properties (area, flowpath lengths, elevations/slopes) using your GIS workflow.
• Ensure units match HDAT expectations (see Assumptions, units & notation).

2) Configure IDF / return periods

• Enter return periods and intensities/depths for standard durations.
• Verify the intensity trend is reasonable and consistent.

3) Run hydrology

• Compute peak flows for each catchment and return period.
• Review:
  • Tc values
  • selected method branch (Rational vs SCS)
  • intensity segment used (5–60, 60–120, 120–1440)

4) Run hydraulics

• Culverts: pick design discharge (catchment + RP), evaluate inlet/outlet control, review governing \(H/D\).
• Channels: size using Manning, review \(y_n\), \(y_c\), velocity, and regime.

5) Road drainage checks (gullies/sags)

• Run gully spacing and sag checks as needed.
• Review spread constraints, capture efficiency, and bypass progression.

6) Generate BOQ

• Generate BOQ outputs and verify assumptions (linings, protection extents, thicknesses).

7) Save and export

• Save .hdat01 and export reports/BOQ outputs.