Earth Science & Energy
Groundwater Transmissivity & Storativity (Theis Aquifer Test)
Calculate groundwater transmissivity & storativity (theis aquifer test) using the stated engineering or scientific relationship and adjustable field inputs.
Preparing your result…
What this calculator does
Calculates Groundwater Transmissivity & Storativity (Theis Aquifer Test) using the formula verified against the cited source.
What your result means
An estimate from the inputs you enter, within the scope stated below — not advice.
Formula
Cooper–Jacob straight line: T = 2.303 Q ÷ (4π Δs) (Δs = drawdown per log cycle of time); S = 2.25 T t₀ ÷ r²
The step-by-step working for your own numbers appears with the result above and in the PDF report.
Frequently asked questions
Symbols and assumptions
- Inputs
- The values entered in the fields above
- • Cooper–Jacob late-time transmissivity T = ln(10)Q/(4πΔs), where Δs is drawdown change over one log10 time decade. Q m³/day and Δs m give T m²/day. Storativity additionally uses S≈2.25Tt0/r².
Sources and review
Reviewed 2026-10-18 · Next review 2027-04-18
- • The current fields estimate T only. Add observation-well distance r and zero-drawdown time intercept t0 for S, using matching time units. This is the late-time straight-line approximation to Theis under aquifer/test assumptions, not a complete Theis curve fit. Require positive fitted slope and assess well loss/boundaries.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Quick reference
| Scenario | Pumping rate (m³/day) | Drawdown change over one log cycle (m) | Distance to observation well (m) | Transmissivity T |
|---|---|---|---|---|
| Worked example | 1,000 | 0.5 | 30 | 366.4678 m²/day |
| Half the amounts | 500 | 0.25 | 15 | 366.4678 m²/day |
| Double the amounts | 2,000 | 1 | 60 | 366.4678 m²/day |
Need the full picture? Get the detailed PDF report with charts, tables, formulas and working steps.
Reviewed 2026-10-18 · Next review 2027-04-18
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