Question

Given below are the two statements.
Statement I: Most dug wells located in dry and hard rock areas, have discontinuous water tables
Statement II: Pumping tests in dug wells involve observation of rates of depletion as well as recuperation of water level during pumping period and also after stoppage of pumping (till water level in well gets sizably recovered)
In light of the above statements, choose the most appropriate answer from the options given below

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is correct but Statement II is false
• D. Statement I is incorrect but Statement II is true

Hint:

Open dug well testing in hard rock: Pumping and Recuperation method determines Specific Capacity ($K/A = \frac{2.303}{t}\log(s_1/s_2)$).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Groundwater hydrology in hard rock (crystalline shield basalt) formations deals with localized fracture networks and non-continuous regional water tables evaluated using recuperation tests.
Key Formula or Approach:
\[ \frac{C}{A} = \frac{2.303}{t} \log_{10}\left(\frac{s_1}{s_2}\right) \quad \text{(Slichter's Recuperation Formula)} \]

Step 2: Detailed Explanation:
1. Statement I: Hard rock terrains (granites, gneisses, basalts) have negligible primary matrix porosity. Groundwater is confined to discontinuous weathered zones, fissures, joints, and fractures, resulting in discontinuous, localized phreatic water tables. Hence, Statement I is true.
2. Statement II: In large-diameter open dug wells, pumping-recuperation tests (Slichter's method) measure the rate of drawdown during pumping and the subsequent rate of water level recovery (recuperation) after stopping pumping to determine the specific capacity per unit area ($\frac{C}{A}$). Hence, Statement II is true.

Step 3: Final Answer:
Hence, Both Statement I and Statement II are true, matching option (A).