The specific yield Sy of an unconfined aquifer is:
Choose the correct answer
Equal to the porosity n
The fraction of groundwater that drains by gravity from the aquifer when the water table drops by one unit (Sy = n - Sr, where Sr = specific retention)
The artesian pressure divided by depth
The transmissivity divided by thickness
Correct Answer
B. The fraction of groundwater that drains by gravity from the aquifer when the water table drops by one unit (Sy = n - Sr, where Sr = specific retention)
Why is this the answer?
Specific yield Sy = n - Sm (Sr = specific retention = moisture held against gravity). Sy typically 0.1-0.3 for sand. Specific retention: 0.02-0.05 for gravel, 0.06-0.12 for fine sand, 0.10-0.20 for silty soil. Sy represents storativity of unconfined aquifer. Storage coefficient S = Sy (unconfined) or << Sy (confined, typically 0.0001-0.001).
Related Hydrology MCQs
More solved Hydrology questions for AE/JE Civil Engineering exams.
- The 'SCS Curve Number' (CN) method for estimating runoff uses CN values that depend on:
- The 'design storm' for urban drainage uses IDF (Intensity-Duration-Frequency) curves...
- If the coefficient of variation of the rainfall values of the existing rain-gauge...
- If base period is 150 days and delta is 0.6 m, duty is
- For base period 120 days and duty 600 ha/cumec, delta is
- Darcy's law for groundwater flow states that the discharge velocity (Darcy flux) v...
Practice more Civil Engineering questions
This MCQ belongs to AE Level Premium Test Series. Full tests include timed attempts, rank comparison and subject-wise analysis.