What measure helps reduce soil erosion in a dam by managing seepage at the downstream toe?

• A. A downstream toe drain should be installed to reduce the risk of soil erosion in the dam
• B. A downstream toe drain cannot reduce erosion
• C. Increase permeability of downstream face
• D. Remove toe drainage

Answer: (A)

Managing seepage at the downstream toe is essential because seepage can cause scour and even piping that destabilizes the dam’s foundation and slope. Installing a downstream toe drain creates a controlled outlet for that seepage, lowering pore water pressures and the hydraulic gradient right at the toe. With seepage being collected and discharged away from the toe, the risk of soil erosion on the downstream slope is reduced, making the dam more stable overall.

Increasing permeability of the downstream face would allow more seepage to flow toward the toe, raising erosion potential rather than reducing it. Removing toe drainage removes the protective path for seepage, increasing erosion risk. Saying a downstream toe drain cannot reduce erosion is incorrect because the drain is specifically designed to manage seepage and protect against erosion.