Glossary of Terms


Green Infrastructure
A design element for a property that uses landscaped systems or engineered systems that mimic natural systems
Bioswale
A channeled depression or trench that receives and holds rainwater runoff (as from a parking lot) and has vegetation (such as grasses, flowering plants) that rids the water of pollutants. These slow water entering the drainage system during storms.
Rain Garden
A planted depression that allows rainwater runoff from impervious urban areas like roofs, driveways, walkways, and compacted lawn areas to be absorbed into the earth
Infiltration Trenches
Long, narrow, gravel-filled areas. They are located in small drainage areas and are used to direct and store stormwater. They have the added benefit of reducing stormwater pollution before it enters local bodies of water. They work effectively when positioned at building downspouts and around building foundations.
Subsidence
The lowering of a portion of the Earth’s crust

Subsidence occurs when large amounts of groundwater have been withdrawn from certain types of soil, such as fine-grained sediments like we have in New Orleans. The soil compacts because the water is partly responsible for holding the ground up. When the water is withdrawn, the soil falls in on itself, causing damage to property and streets (think foundation issues and potholes).

Impervious (non-permeable)
Does not allow water to be absorbed into or through surface, as in concrete, asphalt, roofs
Permeable (pervious)
Allows water to be absorbed into or through the surface, as in permeable paving
Groundwater
Water present beneath the Earth’s surface
Recharged Groundwater
A hydrologic process where water moves downward from surface water to groundwater.
Stormwater Runoff
Rainwater that does not soak into the ground but flows over impervious areas or areas already saturated with water
Flow-through Planter Boxes
Planter boxes can be filled with plants that absorb large amounts of water and can be placed directly below the edge of the roof to catch runoff. These planter boxes can help absorb some of the water during rain events and prevent damage to building foundations.