Research - Datalogger 

Page / - last modified by TerraIndex TerraIndex on 2022/06/10 10:20 

Datalogger 
last modified by TerraIndex TerraIndex
on 2022/06/10 10:20

Table of Contents

Data loggers are elongated devices that can be hung in a monitoring well. They can measure the groundwater at various times over a longer period of time. Depending on the data loggers, different (combinations) of parameters of the groundwater can be measured. After a certain period, the data loggers can be removed from the monitoring well and the measurements can be transferred via a cable to a computer for further processing and interpretation, or read out telemetrically via a GSM modem or bluetooth.
General information 	
Name	data logger.
A specific version is the diver.	
Unit of measure and parameter	Pressure in cm H 2 O.
temperature in 0 C.
EC in mS/cm (depending on type).	
Soil phase	groundwater	
Nature technique	Physical, chemical or probe/sensor	
Place of application	in situ	
Detection Mode	Measurement at ground level / water bottom or on surface of open water	
Applicable in separate layers	Yes with a minimum layer thickness of 1 m	
Soil types for which technology is suitable	•	homogeneous well-permeable sand package
•	one sand package, with poorly permeable layers
•	poorly permeable top layer, cross-section with layers of sand

 	
Land soil/water bottom	land soil and water bottom	
Step in the data collection chain	Sampling, measure or data collection and evaluation	
Moment of availability results	Measurement results are available in the field	
Technology development phase	widening phase or applied routinely	
Method of purchasing	as service, as a product or as a device	
General description of the implementation method	The data logger is suspended in a monitoring well. Measurements are taken at a preset time interval and stored in the memory of the data logger. At the end of the period, all data is read out with a computer.
The following techniques are available for reading the data logger without first removing it from the monitoring well:
•	Data cable: with this cable the data logger can be connected to a computer at ground level near the monitoring well for reading and programming;
•	Diver-NETZ (specific for datalogger type Divers): the datalogger is connected by means of a DDC to a transmitter, with which the data from the datalogger can be sent wirelessly to a PDA or laptop. Monitoring wells can also be networked in this way. The distance range of the transmitter is approximately 100 – 150 m.
•	Telemetry: The data logger is connected to a field modem by means of a cable. Messages are sent from the field modem with the measurement data. The messages can be received at any location. This means that it is no longer necessary to read out the data logger in the field.
•	Reading the data logger with bluetooth.	
Working principle	The data logger is a pressure transducer in which some versions can also measure parameters such as temperature, EC or oxygen content. After programming, the data logger is suspended in a monitoring well. To derive groundwater levels, the use of a so-called 'baro-logger' is necessary. The baro-logger measures the air pressure. With the data from the baro-logger, the measurements of the ordinary data loggers are corrected for air pressure variations (the ordinary data logger measures the air pressure + the pressure of the water column above the data logger). Some data loggers have built-in baro loggers.
After a certain period (depending on the nature and purpose of the assignment and the selected measurement frequency), the data is read from the data logger.
A data logger can also be used to perform surface water level measurements.	
Point / line measurement / volume measurement	Point measurement	
Typical depth range	0 - 300 m and the sensitivity is independent of depth	
Time properties	A data logger can be hung in a monitoring well for a longer period of time (eg monthly, quarterly or half yearly). The data logger can be programmed with which time interval measurements should be performed and stored.
Setting and reading a data logger can take place within 1 hour. Measurement frequency can be preset (between 0.5 sec and 99 hours).	
Measuring rate	Measurement data can be read immediately after the measurement.	
Presentation results	With the accompanying software, the results can be viewed directly in the field.	
Cost	- Standard data logger: approximately €500
- Baro logger: approximately € 350
- Cost of field investigation (including placing monitoring well, driving costs and installing data logger)	
Trends and developments	Read out data via bluetooth.	
 User information 	
Availability	one or a few providers in NL	
Is technology often used?	Very organized	
Research phase in which technology can be applied	Explore, map out, variant selection, design, realization, check, monitoring and aftercare	
Verification measurements / calibration measurements	are often used	
Frequently used application in practice	Various projects where groundwater levels/quality must be recorded for a longer period of time or with a relatively high measuring frequency, such as:
•	monitoring;
•	permeability measurements / pump tests;
•	monitoring the effects of water system interventions (groundwater abstraction / water level change);
•	determine the response of the groundwater system to precipitation events.	
Suitability	In all soil layers, provided that a monitoring well is present with good flow	
Practical experiences in the Netherlands	Data loggers are regularly used by various parties (including municipalities, water boards, provinces, water companies and research and engineering firms)	
“Dos“	Before installing and retrieving a data logger, perform a manual measurement of the groundwater level.
Measure the height at the top of the monitoring well in relation to NAP.
Measuring and registering the depth at which the data logger hangs.
Water pressure correction for air pressure variances.	
“Don'ts”	Hang data logger too shallow (data logger falls dry)
Hang data logger too deep (note measuring range!)	
Also suitable for	Measuring surface water levels.	
References
•	https://www.bodemrichtlijn.nl/Bibliotheek/bodemonderzoek/onderzoekstechnieken/datalogger
Datalogger

Image	Datalogger	
Contents
•	References
•	Datalogger