Beacon Institute has installed an Acoustic Doppler Current Profiler (ADCP) near the USGS gauging station at South Dock at the U.S. Military Academy at West Point, NY (Latitude 41°23'10", Longitude 73°57'20").The ADCP measures the speed and direction of the water current along the horizontal cross-section of the river, as well as acoustic backscatter intensity, an indirect measure of particle concentration in the river. The ADCP emits a sound signal, measured in decibels, that is reflected back when the sound signal meets a particle. The more particles in the water, the greater the acoustic backscatter intensity.
The ADCP does not identify the specific particles; however, high levels of acoustic backscatter could indicate a large phytoplankton bloom, or a windy event in which the bottom layer of river sediment is disturbed, or movement of contaminants, among many other possibilities. Particles measured could include organic and inorganic matter, such as phytoplankton (algae), sand and silt, as well as chemicals (such as PCBs) that can attach to sediment and other solid particles.
North Component of Water Current
The ADCP is measuring the speed and direction of the river’s current in a north/south direction in centimeters per second. Positive velocity magnitude (yellow to red) indicates that water is moving up the river to the north – high tide. Negative velocity magnitude (turquoise to blue) shows water moving to the south, back toward the Atlantic Ocean – low tide.
North Component of Current
Profile (cm/s)
East Component of Water current
Here the ADCP is measuring the flow of current horizontally across the river. While the velocity magnitude is less dramatic, it shows that tidal forces continue to affect velocity variation along cross section of river.
East Component of Current Profile (cm/s)
Acoustic Backscatter Intensity
In this cross-section of the water column, the dark red shows the higher acoustic backscatter intensity, whereas blue shows lower acoustic backscatter intensity. Once this measured raw acoustic backscatter intensity has been adjusted for the attenuation of sound intensity with distance, the higher backscatter intensity will indicate higher particle concentration whereas lower acoustic backscatter intensity will indicate lower particle concentration.
Acoustic Backscatter Intensity
(decibels)
Water temperature
The temperature of the water, measured in Celsius, is higher during the daytime with sunlight and lower with cloudy conditions, with the lowest temperatures at night.
Water Temperature (0C)
