What is the typical maximum slope percentage for a Wet Swale?

What is the typical maximum slope percentage for a Wet Swale?

• A. 0%
• B. Less than 5%
• C. 5% or more
• D. 10% or more

Answer: (B)

Wet swales rely on keeping water in contact with vegetation and in the soil long enough for filtration and infiltration. That calls for a very gentle slope so water moves slowly, preserving the wet conditions and providing residence time for treatment. If the slope were too steep, water would rush through, increasing erosion, washing away vegetation, and reducing the swale’s ability to stay wet and treat pollutants. A flat or near-flat profile can impede drainage, so the design uses a mild incline that maintains wet conditions without accelerating flow. That’s why the concept tested is a gentle maximum slope, not a very steep one.

Wet swales rely on keeping water in contact with vegetation and in the soil long enough for filtration and infiltration. That calls for a very gentle slope so water moves slowly, preserving the wet conditions and providing residence time for treatment. If the slope were too steep, water would rush through, increasing erosion, washing away vegetation, and reducing the swale’s ability to stay wet and treat pollutants. A flat or near-flat profile can impede drainage, so the design uses a mild incline that maintains wet conditions without accelerating flow. That’s why the concept tested is a gentle maximum slope, not a very steep one.