Modified Equation For Storage Coefficient From Time Drawdown Graphs Calculator

Modified Equation For Storage Coefficient From Time Drawdown Graphs:

\[ S = \frac{\tau \cdot t_o}{640 \cdot r^2} \]

Transmissivity (τ):

m²/s

Time at the Point of Intersection (tₒ):

min

Distance from Pumping Well (r):

Storage Coefficient (S):

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1. What is the Modified Equation For Storage Coefficient From Time Drawdown Graphs?

The Modified Equation For Storage Coefficient From Time Drawdown Graphs estimates the storage coefficient of an aquifer using transmissivity, time at the point of intersection, and distance from the pumping well. This equation is particularly useful in hydrogeological studies for analyzing aquifer characteristics.

2. How Does the Calculator Work?

The calculator uses the modified equation:

\[ S = \frac{\tau \cdot t_o}{640 \cdot r^2} \]

Where:

\( S \) — Storage Coefficient (dimensionless)
\( \tau \) — Transmissivity (m²/s)
\( t_o \) — Time at the Point of Intersection (min)
\( r \) — Distance from Pumping Well (m)

Explanation: The equation calculates the storage coefficient by relating transmissivity, time at intersection point, and distance from the pumping well through a modified formula derived from time-drawdown graph analysis.

3. Importance of Storage Coefficient Calculation

Details: The storage coefficient is a crucial parameter in aquifer characterization as it represents the volume of water released from storage per unit decline in hydraulic head. Accurate determination helps in understanding aquifer behavior, groundwater flow modeling, and sustainable water resource management.

4. Using the Calculator

Tips: Enter transmissivity in m²/s, time at intersection point in minutes, and distance from pumping well in meters. All values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the significance of the storage coefficient in hydrogeology?
A: The storage coefficient indicates how much water an aquifer can release from storage when the water table or potentiometric surface declines. It's essential for predicting aquifer response to pumping and recharge.

Q2: How does this modified equation differ from standard storage coefficient formulas?
A: This modified equation specifically utilizes time-drawdown graph intersection points, providing an alternative method for storage coefficient estimation that can be more practical in certain field conditions.

Q3: What are typical ranges for storage coefficient values?
A: For confined aquifers, storage coefficients typically range from 0.00001 to 0.001, while for unconfined aquifers, values range from 0.01 to 0.3.

Q4: When should this modified equation be used instead of traditional methods?
A: This equation is particularly useful when time-drawdown data from pumping tests are available and when traditional curve-matching methods may be less precise or practical.

Q5: What factors can affect the accuracy of this calculation?
A: Measurement accuracy of transmissivity, precise determination of intersection time, correct distance measurement, and aquifer homogeneity can all impact the calculation's accuracy.