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Calcimator

Well Drawdown Calculator

Calculate well drawdown using the Theis/Cooper-Jacob equation from pump rate, transmissivity, storage coefficient, time, and distance.

Inputs

Results

Drawdown

0.215 m

≈ 3 credit cards

Radius of Influence

1,500 m

≈ 5 Eiffel Towers

Calculation MethodCooper-Jacob
Specific Capacity2,320.19 m³/day/m
u Parameter0
How to Use This Calculator
  1. Enter the Pump Rate Q in m³/day and the Aquifer Transmissivity T in m²/day.
  2. Enter the Storage Coefficient S and the Pumping Time in days.
  3. Enter the Distance from the well in meters at which you want to calculate drawdown.
  4. Review Drawdown in meters — the drop in water level at the specified distance.
  5. Check Radius of Influence and Specific Capacity to characterize well performance and aquifer properties.

How the result changes with Pump Rate Q (m³/day)

Pump Rate Q (m³/day)DrawdownRadius of Influence
10,0004.31 m1,500 m
35,00015.085 m1,500 m
65,00028.015 m1,500 m
90,00038.79 m1,500 m

What each input means

Pump Rate Q (m³/day)
Pumping rate in cubic meters per day.
Transmissivity T (m²/day)
Aquifer transmissivity in m²/day. Product of hydraulic conductivity and aquifer thickness.
Storage Coefficient S
Dimensionless storage coefficient. Confined aquifers: 0.0001–0.001. Unconfined: 0.01–0.3.
Pumping Time (days)
Duration of pumping in days.
Distance from Well (m)
Radial distance from the pumping well to the observation point in meters.

How this is calculated

Formula

s = (Q / 4πT) × W(u), where u = r²S / 4Tt

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Pump Rate Q (m³/day) = 500, Transmissivity T (m²/day) = 1000, Storage Coefficient S = 0.001, Pumping Time (days) = 1 = 5 input(s) provided
  2. Calculate Drawdown
    Drawdown
    0.215 = 0.215
  3. Calculate Radius of Influence
    Radius of Influence
    1500 = 1500
  4. Calculate Calculation Method
    Cooper-Jacob = Cooper-Jacob
  5. Calculate Specific Capacity
    Specific Capacity
    2320.19 = 2320.19

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