What is the primary function of an armored spillway?

What is the primary function of an armored spillway?

• A. To safely convey excess stormwater flow while preventing erosion.
• B. To reduce water velocity within the drainage system.
• C. To filter pollutants from runoff.
• D. To store sediment in a basin.

Answer: (A)

Armored spillways are built to carry excess water safely while protecting the structure from erosion. The armored surface—usually rock or reinforced concrete—resists the powerful forces of high-velocity flow that can scour and undermine a spillway and downstream channels. By providing a hard, erosion-resistant path for the outflow, it keeps the discharge route stable and reduces the risk of channels or embankments being washed out during peak storms. This isn’t primarily about reducing velocity throughout the drainage system, filtering pollutants, or storing sediment. Those tasks belong to other stormwater features like energy dissipators, filters, or sediment basins. The main purpose here is to convey excess water without causing erosive damage.

Armored spillways are built to carry excess water safely while protecting the structure from erosion. The armored surface—usually rock or reinforced concrete—resists the powerful forces of high-velocity flow that can scour and undermine a spillway and downstream channels. By providing a hard, erosion-resistant path for the outflow, it keeps the discharge route stable and reduces the risk of channels or embankments being washed out during peak storms.

This isn’t primarily about reducing velocity throughout the drainage system, filtering pollutants, or storing sediment. Those tasks belong to other stormwater features like energy dissipators, filters, or sediment basins. The main purpose here is to convey excess water without causing erosive damage.