Question

Given below are two statements:
Statement I: Vegetative methods, berms and riprap are the methods used for controlling erosion by waves.
Statement II: Riprap consists of loose stones or concrete blocks dumped or hand placed on the side of the embankment not facing the water.
In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement I and Statement II are correct
• B. Both Statement I and Statement II are incorrect
• C. Statement I is correct but Statement II is incorrect
• D. Statement I is incorrect but Statement II is correct

Hint:

Think of the function of riprap:
It acts as an armor layer to absorb the impact of moving water, so it must always be placed on the side facing the water.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Soil erosion along the banks of reservoirs, lakes, and channels is often driven by wave action.
Controlling this erosion requires biological or structural protective measures to absorb or dissipate the kinetic energy of the waves.

Step 2: Detailed Explanation:
Let us evaluate both statements in detail:
- Statement I: Wave-induced erosion can be managed using several methods:
1. Vegetative Methods: Planting water-tolerant grasses or shrubs along the shoreline to bind the soil with their roots and dissipate wave energy.
2. Berms: Small horizontal benches constructed along the slope to break the continuous run-up of waves.
3. Riprap: A layer of stone or concrete blocks designed to protect soil from erosion.
Therefore, Statement I is correct.
- Statement II: Riprap is used to protect the embankment slope from the erosive forces of waves and water currents.
To do this, the loose stones or concrete blocks must be placed on the side facing the water (the upstream slope or wet face of the embankment).
Placing riprap on the dry face (not facing the water) would not provide protection against wave action.
Therefore, Statement II is incorrect.
Since Statement I is correct but Statement II is incorrect, option (C) is the correct choice.

Step 3: Final Answer:
Statement I is correct but Statement II is incorrect.