Glossary

Base Flood Elevation (BFE)

The elevation level that floodwaters are expected to reach or exceed during a 1% annual chance flood event (also called a 100-year flood). Properties built below the BFE are at higher risk for flooding.

Closed Basin

A low-lying area where water has no natural drainage outlet to a river, lake, or ocean. Stormwater in closed basins must evaporate, be absorbed into the ground, or be artificially pumped out, increasing flood risks.

Community Development Block Grant – Disaster Recovery (CDBG-DR)

A federal grant program that provides funding for long-term disaster recovery projects, including stormwater infrastructure improvements, flood mitigation, and wastewater system upgrades.

Detention Pond

A stormwater retention area designed to temporarily store runoff after heavy rain. Unlike retention ponds, detention ponds slowly release water into the drainage system over time, reducing flood risks.

Drainage Basin (Watershed)

An area where all precipitation drains into a common outlet, such as a river, lake, or retention pond. Open basins have natural drainage outlets, while closed basins do not.

Emergency Watershed Protection Program (EWP)

A federal program designed to help communities address sudden watershed impairments caused by natural disasters. Funding may support canal armoring, stormwater improvements, and flood mitigation projects.

Exfiltration Trench

A type of stormwater drainage system that allows rainwater to infiltrate the ground rather than flowing directly into lakes, rivers, or storm drains. These systems help filter pollutants and reduce runoff volume.

Floodplain

A low-lying area adjacent to a river, stream, or coast that is naturally prone to flooding. Floodplains are regulated by FEMA, and construction in these areas often requires special permits.

Flood Mitigation

A set of strategies designed to reduce the impact of flooding on homes, businesses, and infrastructure. Common mitigation efforts include stormwater system improvements, property elevation, and floodproofing measures.

Green Infrastructure

A type of stormwater management that uses natural processes to capture, filter, and slow stormwater runoff. Examples include rain gardens, permeable pavement, and wetland restoration.

Hydrology

The scientific study of how water moves through the environment, including rainfall patterns, groundwater absorption, and surface runoff. Understanding hydrology is essential for stormwater planning.

Impervious Surface

A surface that does not absorb water, such as roads, driveways, and rooftops. Impervious surfaces increase stormwater runoff and can contribute to flooding.

Low Impact Development (LID)

A set of stormwater management practices that minimize runoff and improve water quality by using natural or engineered solutions, such as rain gardens, bioswales, and retention ponds.

Mosquito Control Open-Channel Canals

A network of drainage canals maintained by Volusia County to prevent standing water and reduce mosquito breeding grounds. These canals also play a role in stormwater management and flood prevention.

National Flood Insurance Program (NFIP)

A FEMA program that provides flood insurance coverage for property owners in participating communities. Flood insurance rates are based on flood zone maps and elevation certificates.

One-Way Backflow Preventer

A valve installed in storm drains to prevent water from flowing backward into streets and neighborhoods during high tide or heavy rainfall. This is especially useful in coastal flood-prone areas.

Open Basin

A drainage basin that has a natural outflow to a larger waterbody, such as a river or ocean. Unlike closed basins, open basins allow excess stormwater to drain more efficiently.

Pump Station

A mechanical system used to remove excess stormwater from low-lying areas, particularly closed basins or areas with poor drainage. Pump stations are vital during heavy rain events and hurricanes.

Retention Pond

A permanent stormwater pond designed to store water indefinitely and help prevent downstream flooding. Unlike detention ponds, retention ponds do not drain out water quickly but allow it to gradually seep into the ground or evaporate.

Storm Surge

A rise in sea level caused by hurricanes or tropical storms, which can lead to coastal flooding and backflow issues in drainage systems.

Stormwater

Rainwater that runs off roads, driveways, and rooftops, often collecting debris and pollutants as it moves through the environment. Proper stormwater management prevents flooding and protects water quality.

Stormwater Fees

Charges collected by local governments to fund stormwater infrastructure maintenance and improvements. These fees help ensure proper drainage, reduce flood risks, and improve water quality.

Stormwater Management

A system of pipes, ponds, canals, and drainage infrastructure designed to control and direct rainwater runoff, reducing the risk of flooding, erosion, and water pollution.

Tailwater

The water level in a receiving body (such as a river, pond, or ocean) at the discharge point of a drainage system. High tailwater levels can slow stormwater drainage and lead to flooding.