Drawdown In Well 1 Given Aquifer Constant Calculator

Formula Used:

\[ s_1 = s_2 + \frac{Q \cdot \log_{10}\left(\frac{r_2}{r_1}\right)}{2.72 \cdot T} \]

Drawdown in well 2 (s₂):

Discharge (Q):

m³/s

Radial Distance at Observation Well 2 (r₂):

Radial Distance at Observation Well 1 (r₁):

Aquifer Constant (T):

Drawdown in well 1 (s₁):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Drawdown in Well 1 Formula?

The formula calculates the drawdown in well 1 based on known drawdown in well 2, discharge rate, radial distances from observation wells, and aquifer constant. This is derived from the Theis equation for groundwater flow in confined aquifers.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ s_1 = s_2 + \frac{Q \cdot \log_{10}\left(\frac{r_2}{r_1}\right)}{2.72 \cdot T} \]

Where:

\( s_1 \) — Drawdown in well 1 (m)
\( s_2 \) — Drawdown in well 2 (m)
\( Q \) — Discharge rate (m³/s)
\( r_2 \) — Radial distance at observation well 2 (m)
\( r_1 \) — Radial distance at observation well 1 (m)
\( T \) — Aquifer constant (coefficient of transmissibility)

Explanation: The formula accounts for the logarithmic relationship between drawdown and radial distance in groundwater flow systems.

3. Importance of Drawdown Calculation

Details: Accurate drawdown calculation is crucial for well design, aquifer characterization, and predicting the impact of pumping on groundwater levels.

4. Using the Calculator

Tips: Enter all values in appropriate units. Drawdown values should be non-negative, discharge and radial distances should be positive, and aquifer constant must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the significance of the 2.72 constant?
A: The constant 2.72 is approximately equal to e (Euler's number) and appears in the derivation from the exponential integral solution to the Theis equation.

Q2: When is this formula applicable?
A: This formula applies to confined aquifers with fully penetrating wells and homogeneous, isotropic aquifer properties.

Q3: What are typical units for aquifer constant?
A: The aquifer constant (transmissivity) is typically measured in m²/day or m²/s, depending on the units used for discharge.

Q4: How does radial distance affect drawdown?
A: Drawdown decreases logarithmically with increasing radial distance from the pumping well.

Q5: What are limitations of this approach?
A: This approach assumes steady-state conditions, homogeneous aquifer properties, and may not account for boundary effects or partial penetration.