Which of the following is an example of green infrastructure that reduces stormwater runoff?

• A. Concrete channels that rapidly move runoff to sewers.
• B. Asphalt expansion to increase road capacity.
• C. Bioswales and rain gardens.
• D. Seawalls.

Answer: (C)

Green infrastructure uses plants, soil, and natural processes to slow, capture, and treat rainfall, so less water becomes rapid runoff. Bioswales and rain gardens exemplify this approach. A bioswale is a vegetated channel that collects runoff from roofs or pavement, slows it down, and promotes infiltration while filtering pollutants. A rain garden is a shallow, planted depression that absorbs stormwater, allowing some of it to soak into the ground and helping remove contaminants before it reaches streams or sewers. Together, they reduce the volume and speed of runoff and improve water quality.

The other options rely on hard, impermeable surfaces or coastal defenses that move water away quickly or protect land without addressing urban stormwater. Concrete channels and sewer systems speed water to the sewer, increasing runoff downslope. Expanding asphalt increases impermeable area, leading to more runoff. Seawalls protect shorelines but don’t reduce inland stormwater runoff.