Wet and dry intake towers in reservoirs: identify the correct combination Which option correctly states the conditions for wet vs. dry intake towers and buoyancy?

Introduction / Context:
Intake towers control the offtake of water from reservoirs at selectable levels. Two common configurations are “wet” towers, which are flooded to reservoir level, and “dry” towers, which remain dry inside except for intake conduits. Understanding buoyancy and operational implications is fundamental to safe design.

Given Data / Assumptions (statements referenced):

• (a) If ports are closed, a dry intake tower will not have water inside (correct).
• (b) Even if ports are closed, a wet intake tower is filled up to reservoir level (correct).
• (c) Dry intake towers require heavier construction to resist buoyant forces (correct).
• (d) No buoyant force acts on wet intake towers (incorrect; buoyancy acts on any submerged structure).

Concept / Approach:
Buoyancy acts on a submerged volume regardless of whether the interior is flooded or not; however, a dry tower encloses air and experiences net uplift equal to displaced water weight. A wet tower, being flooded, has reduced net buoyancy but is still subject to hydrostatic pressures and stability checks.

Step-by-Step Solution:

Verification / Alternative check:
Design manuals for intake structures consider uplift, hydrostatic pressures, and overturning for both tower types, confirming the above judgments.

Why Other Options Are Wrong:

• (a) alone is incomplete; (d) being false invalidates “All of the above”.
• “Only (d) correct” is clearly wrong.
• “None correct” is also wrong as (a)–(c) are valid.

Common Pitfalls:
Assuming flooding a tower eliminates buoyant effects; it mainly reduces net buoyancy but does not remove hydrostatic actions.

Final Answer:
Statements (a), (b), and (c) are correct; statement (d) is incorrect