Reservoir sediment behavior: Which statements about bed load, suspended sediment deposition zones, and capacity loss due to sedimentation are correct?

Introduction / Context:
Understanding how sediment moves and deposits in reservoirs is central to predicting capacity loss, intake clogging risks, and long-term sustainability of water-supply projects.

Given Data / Assumptions:

• Typical alluvial river inflow into a reservoir.
• Normal gradation from bed load to suspended load.
• Longitudinal sorting as velocity drops within the reservoir pool.

Concept / Approach:

As flow enters a reservoir, velocities fall; the heaviest fractions (bed load and coarse suspended particles) settle first near the head of the reservoir, while finer silt and clay may travel farther, depositing closer to the dam or remaining in suspension for extended periods. Any deposition incrementally reduces capacity over time.

Step-by-Step Solution:

Verification / Alternative check:

Bathymetric surveys over years confirm delta growth from the head and finer deposits closer to the dam. Sediment management plans are based on these patterns.

Why Other Options Are Wrong:

• Since (a)–(d) are all correct, no single alternative contradicts them; hence (e) is right.

Common Pitfalls:

• Assuming uniform deposition along the length.
• Overlooking trap efficiency and density variations.

Final Answer:

All the above.