New Jersey Water Science Center Glossary

A

Acoustic Doppler Current Profiler

Electronic instruments used by the U.S. Geological Survey (USGS) to measure water velocity, depth, and discharge by measuring reflected soundwaves to calculate distance and movement in rivers and estuaries.

Aquifer

A geological formation that can store and transmit groundwater, providing a source for wells and springs.

C

Confined aquifer

An aquifer between two confining units that prevent direct hydraulic connection of the aquifer with land surface, keeping the aquifer under pressure.

Confining unit

A geological formation with little to no permeability that inhibits the flow of groundwater

D

Datum

A USGS datum is a geodetic reference system used to define precise horizontal and vertical positions for mapping, surveying, and geospatial data in the United States.

Discharge

The volume of water moving down a stream or river per unit of time, typically expressed in cubic feet per second (cfs).

F

Ft

feet

Ft/s

Feet per second, a measure of velocity

G

Gage height

The height of the water surface above an established datum, often used interchangeably with the more general term stage

Groundwater

Water that is found beneath the Earth's surface in soil pore spaces and fractures of rock formations, contributing to aquifers and influencing surface water.

Groundwater recharge

Processes through which water can enter a groundwater system.

H

Hydraulic modeling

The simulation and analysis of the behavior of water flow in various systems, such as rivers, channels, pipelines, or stormwater networks.

L

LiDAR

Light Detection and Ranging (LiDAR) systems use lasers to measure the elevation of objects on the ground, in forests, under water and even in buildings.

R

Rating Curve

A graphical representation of the relationship between the water surface elevation (stage) at a specific location and the corresponding flow rate (discharge) in a river or stream.

S

Stage

The height of the water surface above an established datum at a specific location in a stream or lake.

Streamflow

The flow of water in a natural or artificial stream, measured in cubic feet per second (cfs)

U

Unconfined Aquifer

An aquifer that is hydraulically connected to land surface and is not capped by a confining unit, allowing water to flow freely in response to precipitation and other surface conditions.

Unmanned Aerial System

An unmanned aircraft system that includes a drone, typically weighing less than 55 pounds (25 kg), along with the associated ground control station and communication links.

W

Wading Rod

A wading rod is a graduated, hand-held rod used to measure water depth and position current meters in shallow streams for streamflow measurements.

Water Table

The upper surface of an unconfined aquifer, below which the soil or rock is saturated with water.