What Is the Cooper-Jacob Aquifer Drawdown & Pumping Test Calculator?
The Cooper-Jacob straight-line method simplifies Theis radial flow analysis for pumping tests where parameter u is small (u < 0.05).
Under these late-time or near-well conditions, the exponential integral W(u) is approximated by a natural logarithm, yielding a linear drawdown relationship against log time.
This calculator computes parameter u, verifies validity, determines predicted drawdown s(r,t), semi-log slope Δs, and zero-drawdown intercept t0.
How Does the Cooper-Jacob Aquifer Drawdown & Pumping Test Calculator Work?
The calculation evaluates user-provided measurements using recognized domain equations, converts between measurement units, and adjusts for real-world efficiency factors.
Cooper-Jacob Aquifer Drawdown & Pumping Test Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Cooper-Jacob logarithmic expansion of the Theis well equation valid for dimensionless parameter u < 0.05.
How to Use the Cooper-Jacob Aquifer Drawdown & Pumping Test Calculator
- Enter your primary measurements in the input fields above.
- Select your preferred units (e.g. metric or imperial) if applicable.
- Review or adjust operational assumptions such as field efficiency.
- Click Calculate to instantly generate the full results breakdown and visual chart.
- Use the Reset button at any time to clear the form and test a new scenario.
Step-by-Step Example Calculation
Observation Piezometer (r = 50m, t = 48h, Q = 2000 m³/day)
Input Values:
Understanding Your Result
Your calculated result represents the realistic operational capacity or baseline output under the specified conditions. Comparing theoretical and effective outputs reveals the direct impact of turns, overlap, and practical downtime.
Factors That Affect the Result
Field terrain, operator experience, equipment maintenance, overlap margin, and weather conditions can significantly influence real-world output.
When Should You Use This Calculator?
Use this calculator whenever you need quick, verified estimates for job planning, budgeting, equipment sizing, or project timelines.
Assumptions & Limitations
- The Cooper-Jacob approximation introduces less than 1% error when u < 0.01 and less than 5% error when u < 0.05.
- For early-time data (u > 0.05), the full Theis curve matching method W(u) must be utilized.
Frequently Asked Questions
Calculation Accuracy & Reference Note
This calculator implements verified, deterministic mathematical equations based on published standards. Results should be treated as professional engineering estimates; always verify critical operations with local equipment manuals and site inspections.