Static & Dynamic Water Level Calculator
Calculate the static water level (SWL), dynamic water level (DWL), and drawdown in a pumping well using field measurements and the Theis or Cooper-Jacob method.
Well & Aquifer Parameters
Optional: Observed Field Data
Results will appear here.
Formulas Used
Theis (1935) — Transient Radial Flow:
s = Q / (4πT) × W(u)
where u = r²S / (4Tt)
W(u) = −γ − ln(u) + u − u²/(2·2!) + u³/(3·3!) − ⋯ (Euler–Mascheroni γ = 0.5772)
Cooper-Jacob (1946) — valid when u < 0.05:
s = (2.303Q / 4πT) × log₁₀(2.25Tt / r²S)
Dynamic Water Level: DWL = SWL + s (depth below ground surface)
Specific Capacity: Sc = Q / s (m³/day per m of drawdown)
Hydraulic Conductivity: K = T / b
Assumptions & References
- Aquifer is homogeneous, isotropic, and of uniform thickness (confined aquifer assumed).
- Well fully penetrates the aquifer; pumping rate is constant.
- Water is released instantaneously from storage; no leakage from adjacent layers.
- Theis W(u) computed via convergent series (Abramowitz & Stegun, 1964, §5.1).
- Cooper-Jacob approximation valid only when u = r²S/(4Tt) < 0.05.
- For unconfined aquifers, replace s with s − s²/(2b) (Jacob correction) for large drawdowns.
- References: Theis (1935) Trans. AGU 16:519–524; Cooper & Jacob (1946) Trans. AGU 27:526–534; Freeze & Cherry (1979) Groundwater, Prentice-Hall.