Reservoir Storage and Flood Control MCQ with answer and solution

Concept

Reservoir sedimentation leads to a progressive loss of storage volume over time, impacting both water supply and flood control capabilities.

Step-by-step solution

1. Identify the process: Incoming rivers bring suspended sediments into the reservoir. 2. Observe the hydrodynamic change: As water enters the wider reservoir area, flow velocity decreases significantly. 3. Understand the outcome: Sediments settle out of suspension (deposition) and accumulate over the years. 4. Conclude the effect: This accumulation occupies the useful storage volume, thereby reducing the storage capacity of the reservoir.

Explanation

Sedimentation in reservoirs occurs when sediment-laden water enters the reservoir, slows down, and deposits its suspended load. Over time, these deposited sediments accumulate at the bottom, directly occupying and reducing the available storage capacity of the reservoir.

Why the other options are wrong

A: Head loss is related to friction and flow through pipes or channels, not reservoir sedimentation. C: Turbulence is typically reduced as water enters a larger reservoir basin due to decreased velocity, but sediment deposition itself doesn't cause this reduction as the primary effect on the reservoir's utility. D: Flood routing is a hydrological computation method, not a physical property reduced by sedimentation.

Shortcut

Remember that silt deposition physically takes up space, decreasing storage.

Common mistake

Confusing reservoir sedimentation with downstream river siltation or assuming it increases capacity due to displacement.