Bassets Bridge Rd. looking east across the Wallkill. Stage logging and communications equipment are housed in the box mounted to the post at right.
An ultrasonic distance sensor and air thermometer are mounted to the bridge abutment beneath the northwest corner of the bridge. Every 15 minutes the distance sensor emits an acoustic pulse directed at the water surface and measures the time between emission and return of the pulse. By knowing the position of instrument and the speed of sound in air, this time is converted to a river stage. The air temperature is used to correct for variations in the speed of sound in air.
The staff plate mounted next to the distance sensor is used to visually detemine river stage and check distance sensor measurements.
During low flow conditions it may be useful to bring a pair of binoculars to accurately read the staff plate from the bridge.
|
U.S. Department of the Interior, U.S. Geological Survey
Maintainer: New York District URL: http://ny.water.usgs.gov/projects/wallkill/pics/unionpics.html Last update: 11:10:25 Wednesday 22 August 2001 Privacy Statement || Disclaimer |
|