Question

Arrange the recommended values of maximum return period for construction of different soil and water conservation structures. A. Storage and diversion dams with permanent spillways, B. Earthen dams with storage having natural spillways, C. Terrace outlets and vegetated waterways, D. Field diversion, E. Dam for stocking the water.

• A. A \(>\) B \(>\) C \(>\) D \(>\) E
• B. A \(>\) C \(>\) E \(>\) D \(>\) B
• C. A \(>\) B \(>\) E \(>\) D \(>\) C
• D. B \(>\) C \(>\) A \(>\) D \(>\) E

Hint:

Permanent and high-risk water conservation structures are designed for higher return periods than smaller field structures.

Answer 1

The Correct Option is C

Concept:
Return period is important in the design of soil and water conservation structures. Larger and more permanent structures are designed for higher return periods.

Step 1: Highest return period.
Storage and diversion dams with permanent spillways are important permanent structures, so they require the highest return period. \[ \text{Highest}=A \]

Step 2: Next important structure.
Earthen dams with storage and natural spillways also need high return period. \[ \text{Next}=B \]

Step 3: Remaining structures.
Dams for stocking water, field diversions, terrace outlets and vegetated waterways are then arranged according to their relative design importance. \[ E>D>C \]

Step 4: Final order. \[ A>B>E>D>C \] \[ \therefore \text{Correct Answer is (C)} \]