Glossary of Terms

Green Infrastructure

A design element for a property that uses landscaped systems or engineered systems that mimic natural systems


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.


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Subsidence occurs when large amounts of groundwater have been withdrawn from certain types of soil, such as fine-grained sediments like we have in New Orleans.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 When the water is withdrawn, the soil falls in on itself, causing damage to property and streets (think foundation issues and potholes).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


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.