Q: The water level in Lake Lanier is reported daily in the AJC weather section. Usually the rise or fall is minute — for example, 0.01 ft. What instrument (or instruments) is used to record that level of accuracy? Are satellites somehow employed? And how many gallons of water is represented by just a 0.01 foot rise or fall for Lake Lanier?
—Dan Cowles, Cumming
A: Three different devices are used monitor the reservoir water level: a float in a stilling well, a submersible pressure transducer (bubbler system) and an external staff gage.
Water levels are recorded every 15 minutes, Lisa Hunter, chief of public affairs for the U.S. Army Corps of Engineers Mobile District, told Q&A on the News via email.
These separate sensors are used, and redundancy checks are performed monthly to ensure the accuracy of the water level monitors, she wrote.
Satellites are not used to measure the water level, however they are used to assist in transmission of data.
The volume of 0.01 foot of water varies with the level of the reservoir.
At Lake Lanier’s current elevation of 1,064.72 feet, 0.01 foot of water is approximately 350 ac-ft or 114 million gallons, according to the Corps of Engineers Mobile District.
Fast Copy News Service wrote this column. Do you have a question? We’ll try to get the answer. Call 404-222-2002 or email q&a@ajc.com (include name, phone and city).
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