Stormwater Management and Hydrology Flashcards

A check dam installed in a swale is primarily designed to:

Answer: Reduce flow velocity and promote sediment settling in the channel

Check dams reduce the velocity of flow in drainage channels and swales, promoting sediment deposition and reducing the channel's erosive energy.

What is the purpose of a diversion dike on a construction site?

Answer: To redirect clean runoff away from disturbed areas or to route runoff to a BMP

Diversion dikes are earthen berms that redirect surface runoff away from disturbed areas or channel it toward a sediment control BMP to prevent uncontrolled runoff.

Which stormwater BMP provides the most effective long-term management of runoff quality after construction is complete?

Answer: Permanent stormwater pond or bioretention area

Permanent stormwater management facilities like detention ponds or bioretention areas provide long-term water quality and quantity control after construction activities have ended.

Sheet flow in stormwater hydrology describes:

Answer: Thin, uniform flow across a broad surface with no defined channel

Sheet flow is the thin layer of water that moves across a surface in a relatively uniform depth without concentrating into a defined channel, and it is less erosive than concentrated flow.

A level spreader is used to:

Answer: Convert concentrated flow back to sheet flow before it enters a vegetated buffer

Level spreaders convert concentrated runoff into sheet flow so it can be dispersed across a vegetated buffer strip or filter area, reducing erosive velocity and promoting infiltration.

Why is it important to minimize runoff velocity on a construction site?

Answer: Lower velocity reduces the erosive energy that detaches and transports soil particles

Runoff velocity directly determines erosive energy; slower flows have less capacity to detach and transport soil particles, reducing overall sediment production and transport.