One of the first questions we are asked when talking about our water level loggers is “why does my water level data need to be compensated for barometric pressure”

Firstly to explain this we need to look at the two components which vary the pressure being applied to the diaphragm of the pressure sensor, these are the water level and the barometric pressure.

Barometric Pressure

Barometric pressure is the pressure applied by the atmosphere on to the ground around us. The level of barometric pressure is influenced by two main factors, these are Temperature change and Weather systems. Temperature change variation causes the density of air to change, thus varying barometric pressure, change also in humidity can be linked to barometric pressure change. This change in barometric pressure is also used by meteorologists to monitor and predict the changes we see in weather on a daily basis.
The change in barometric pressure is referred to as the diurnal shift. In some areas of the world the diurnal shift can be significant to causes variations of up to 0.30m per day.

What do I need to consider when monitoring water levels?

When conducting the measurement of water level, your product selection is often determined by the measurement period. For example if your measurement period is only for a short period, less than a day, the need to continually measure barometric pressure may not be required. Our Dipperlog Nano systems will always take a single barometric reading and use this for compensation. However if the location / conditions at site or the monitoring is for a long period of time we strongly recommend the use of Barlog sensor to compensate for barometric pressure. Alternatively a vented Dipperlog Nano can be used, as the sensor will provide automatic temperature compensation.

When downloading the data, we always recommend downloading the Barlog information first followed by the Dipperlog Nano pressure data to ensure all recorded readings can be compensated. If no Barlog is used a single value will be used from the initial setup of the sensor.

For more information or to discuss the compensation of water level data please feel free to contact us. sales@bellflowsystems.co.uk