Glossary
Erosion
The process by which increased volume and velocity of urban runoff wears away soil and sediment.
Example:
Uncontrolled erosion from a construction site can lead to large gullies forming on hillsides and sediment clogging nearby waterways.
Flooding
The overflow of water onto land that is normally dry, often exacerbated in urban areas by high volumes of runoff.
Example:
During intense downpours, inadequate storm drains can lead to widespread street flooding, making roads impassable.
Green Infrastructure
A network of natural and semi-natural systems designed to manage stormwater, improve air quality, and provide other environmental benefits.
Example:
A city's plan to integrate more parks, street trees, and rain gardens is an example of investing in green infrastructure to combat urban heat island effect and runoff.
Green Roofs
Rooftops covered with vegetation and a growing medium, designed to absorb rainwater and reduce runoff.
Example:
The new office building features a green roof that not only absorbs stormwater but also provides insulation and a habitat for pollinators.
Groundwater Recharge
The process by which water seeps into the ground and replenishes underground aquifers.
Example:
Forests are excellent at facilitating groundwater recharge, as their soil and root systems allow rainwater to slowly infiltrate.
Impervious Surfaces
Man-made surfaces such as concrete, asphalt, and rooftops that prevent water from infiltrating the soil.
Example:
The vast parking lot of a shopping mall is a prime example of an impervious surface, contributing significantly to local runoff.
Permeable Pavement
Paving materials with pores or gaps that allow water to seep through and infiltrate the ground below.
Example:
A new bike path made of permeable pavement allows rainwater to drain directly into the soil, preventing puddles and runoff.
Pollution
Contaminants like oil, trash, chemicals, and debris picked up by urban runoff and transported into water bodies.
Example:
A rainbow sheen on a puddle after a rainstorm indicates oil pollution from vehicles, which will eventually be carried into a nearby stream.
Rain Gardens
Depressions planted with native vegetation designed to collect, absorb, and filter stormwater runoff from impervious surfaces.
Example:
Homeowners can create a small rain garden in their yard to capture runoff from their downspouts, preventing it from flowing into the street.
Urban Runoff
Water from rain and snow that flows over man-made surfaces like streets and buildings, unable to soak into the ground.
Example:
After a heavy thunderstorm, the streets of a city become rivers of urban runoff, carrying leaves and litter towards storm drains.
Water Infiltration
The process by which water penetrates the ground surface and moves downward into the soil.
Example:
Planting native grasses with deep roots can significantly improve water infiltration in a suburban yard, reducing the need for irrigation.