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Cooper-Jacob Straight-Line Aquifer Transmissivity Calculator

The Cooper-Jacob method simplifies Theis analysis by plotting drawdown against logarithmic time, yielding a straight line for u < 0.01.

Calculated Result
183.2 m²/day

Aquifer Transmissivity (T)

Storage Coefficient (S)

5.144e-4

Time Intercept (t0)

0.0031 days

Aquifer Type

Confined (S < 0.005)

Calculation Breakdown

  1. Calculate transmissivity T = 2.303·Q / (4π·Δs)T = (2.303 * 1200) / (4π * 1.2) = 183.2 m²/day
  2. Compute storativity S = 2.25·T·t0 / r²S = (2.25 * 183.2 * 0.0031) / (50²) = 5.144e-4

Idealized Semi-Log Drawdown Curve

Interactive visualization based on your current inputs

Drawdown
0.00.61.21.82.44.5 min (t0)10 min45 min (1 cycle)450 min (2 cycles)Time (min)Drawdown (m)

What Is the Cooper-Jacob Straight-Line Aquifer Transmissivity Calculator?

The Cooper-Jacob method simplifies Theis analysis by plotting drawdown against logarithmic time, yielding a straight line for u < 0.01.

How Does the Cooper-Jacob Straight-Line Aquifer Transmissivity 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 Straight-Line Aquifer Transmissivity Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

T = \frac{2.303 Q}{4\pi \Delta s}, \quad S = \frac{2.25 T t_0}{r^2}

The slope across one log cycle of time provides transmissivity, while the zero-drawdown time axis intercept yields storativity.

How to Use the Cooper-Jacob Straight-Line Aquifer Transmissivity Calculator

  1. Enter your primary measurements in the input fields above.
  2. Select your preferred units (e.g. metric or imperial) if applicable.
  3. Review or adjust operational assumptions such as field efficiency.
  4. Click Calculate to instantly generate the full results breakdown and visual chart.
  5. Use the Reset button at any time to clear the form and test a new scenario.

Step-by-Step Example Calculation

Pumping Test Analysis

Input Values:

pumpingRateM3PerDay:1200
drawdownDeltaPerLogCycleM:1.2
zeroDrawdownTimeInterceptMinutes:4.5
radialDistanceM:50

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

  • Ensure t0 is entered in minutes; calculation converts to days automatically.

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.

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