Stormwater Management Practices Flashcards
7 cards from real CESSWI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Stormwater Management Practices flashcards as text
In a constructed stormwater wetland, the shallow marsh zone typically operates at what average water depth to support emergent vegetation?
Answer: 6–18 inches
The shallow marsh zone of a constructed wetland is typically maintained at 6–18 inches depth, which supports emergent plants like cattails and bulrushes that provide biological treatment.
Which BMP design parameter ensures that sediment trapped in a basin will not be resuspended and discharged during large storm events?
Answer: Length-to-width ratio
A length-to-width ratio of 3:1 or greater promotes plug flow, reducing turbulence and short-circuiting that could resuspend settled sediment during high-flow events.
A stormwater harvesting system (cistern or rain barrel) primarily reduces which component of the urban water cycle?
Answer: Runoff volume by capturing and reusing rainfall
Stormwater harvesting captures rooftop runoff for non-potable reuse (irrigation, toilet flushing), directly reducing the volume of stormwater discharged to drainage systems.
When inspecting a grassed swale, which condition indicates that the swale is NOT functioning properly?
Answer: Rill erosion channels and bare soil visible along the flow path
Rill erosion and bare soil in a grassed swale indicate that flow velocities are exceeding permissible limits or vegetation is inadequate, causing erosion rather than filtration.
The rational method equation Q = CiA calculates peak runoff rate. What does the coefficient 'C' represent?
Answer: Runoff coefficient reflecting land cover and soil type
The runoff coefficient C (dimensionless, 0–1.0) accounts for the fraction of rainfall that becomes surface runoff based on land use, soil type, and slope.
What is the purpose of a forebay in a stormwater pond or wetland design?
Answer: Pre-settle coarse sediment near the inlet to protect the main pool
A forebay is a smaller, deeper cell at the inlet that traps coarse sediment and debris before flow enters the main treatment area, making sediment removal easier and protecting the main pool.
Under Low Impact Development (LID) principles, what is the primary goal when managing stormwater from a new development?
Answer: Mimic pre-development hydrology by managing runoff at the source
LID aims to replicate pre-development hydrology through distributed, small-scale practices that promote infiltration, evapotranspiration, and retention close to where rain falls.