PETER WADE | BEFORE YOU MODEL
Preparation prompts, not validation or technical sign-off.

1. PURPOSE
What question should the model answer? Which output matters?

2. SYSTEM
Define boundaries, phases, flows, spatial extent and time scale.

3. INPUTS
Record value, unit, source and uncertainty. Separate measured, assumed and fitted inputs.

4. PROCESSES
Which mechanisms are included or excluded? Where relevant, consider equilibrium, kinetics, transport and database choices.

5. CHECKS
Check units, conservation, warnings and limiting cases. Keep calibration separate from independent evaluation.

6. SENSITIVITY AND REPRODUCIBILITY
Vary uncertain inputs and assumptions. Record software version, database, input files and changes.

Final question: What would need to change for this conclusion to no longer hold?

Official software resource: https://www.usgs.gov/software/phreeqc-version-3
Free educational checklist for personal study. Follow course and project guidance.
28 September 2026