As the use of submersible data loggers increases, more and more questions about what to do during the winter months are raised.
- Should I remove them from the environment?
- What happens if they freeze?
- Will they record accurately in the colder temperatures?
- Can I trust the data recorded at lower temperatures?
- These answers frequently are reliant on the type of deployment and water being monitored.
If you are monitoring a wetland or other shallow body of water, it is recommended that you remove any submersible dataloggers during the winter months. Since water expands when it freezes, any data logger encased in ice risks the transducer membrane being damaged or ruptured. Once that occurs, the datalogger can no longer accurately measure pressure or report the depth of the water above it.
Many streams, lakes and ponds are being monitored for water level and temperature these days. If the water is swift moving, as in many streams, or deep enough, it will not fully freeze. As long as the datalogger is deployed below any ice that may form, it will continue to monitor water levels without errors.
Groundwater Monitoring Wells
Groundwater 10m or more below ground surface is mostly unaffected by seasonal temperature changes. Any datalogger suspended at this depth or lower will continue to accurately record water levels year round. Groundwater less that 10m below ground surface can experience temperature fluctuations with the changing seasons. During the winter months, while you might see a drop in the temperature of these shallow groundwater wells, they rarely freeze unless above the frost line. Those submersible data loggers which allow for a temperature compensation should continue to record your water level changes accurately. Even if a layer of ice forms on the surface of the water, as long as your data logger is below the freeze line, you will continue to collect accurate data. Water in an urban setting is also less likely to freeze because it remains warmer than rural waters due to the ground insulating effect of pavement.
Water in a pumping well can be turbulent which it makes it unlikely to freeze. Water in motion rarely freezes. In these types of wells any pressure transducer is normally installed below the pump which further protects if from becoming encased in ice. During the winter months there is little risk to these dataloggers.