Question

The aquifer characteristics influencing yield of an artesian well are:
(A) hydraulic conductivity
(B) transmissibility
(C) coefficient of storage
(D) drawdown
(E) circle of influence
Choose the correct answer from the options given below:

• A. (A), (B) and (D) only.
• B. (A), (B) and (C) only.
• C. (A), (B) and (E) only.
• D. (B), (C) and (D) only.

Hint:

For a confined aquifer, the storage coefficient (\( S \)) is very small (\( 10^{-5} \) to \( 10^{-3} \)) because water is released only by the compaction of the aquifer skeleton and expansion of water.
In contrast, unconfined aquifers have a high storage coefficient equal to their specific yield (\( 0.1 \) to \( 0.3 \)).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
An artesian well is a well drilled into a confined aquifer where the water level rises above the top of the aquifer under hydrostatic pressure.
The sustainable yield of water from such a well is governed by the physical properties of the aquifer material.

Step 2: Detailed Explanation:
Let us evaluate each parameter to determine if it is an inherent aquifer characteristic:
1.Hydraulic conductivity (A): This measures the aquifer's ability to transmit water through its pore spaces under a hydraulic gradient.
It is a fundamental physical property of the aquifer skeleton and fluid.
Thus, (A) is an aquifer characteristic.
2.Transmissibility (B): Transmissibility (\( T = K \cdot b \)) is the rate at which water is transmitted through a unit width of the confined aquifer under a unit hydraulic gradient, where \( b \) is the aquifer thickness.
Thus, (B) is an aquifer characteristic.
3.Coefficient of storage (C): Also known as storativity (\( S \)), this represents the volume of water released from or taken into storage per unit surface area of the aquifer per unit change in head.
Thus, (C) is an aquifer characteristic.
Drawdown (D) is the drop in water level inside the well during pumping, which is an operational well parameter rather than an inherent aquifer characteristic.
The circle of influence (E) is the radial distance from the well to the limit of the cone of depression, which varies dynamically with the pumping rate and time.

Step 3: Final Answer:
The aquifer characteristics that influence the yield of an artesian well are hydraulic conductivity, transmissibility, and the coefficient of storage.