Re: Equipment for national monitoring

[Bruce Metelerkamp]

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This most recent thread on sowacs should yield some interesting discussion.
The need for reliable long-term site soil moisture monitoring equipment
certainly presents a challenge.

For discussion I would like to propose that the more important requirements
of such a system in order of importance are:

1. stable over the long term (for example gypsum blocks degrade).
2. no maintenance required (tensiometers must be attended to?)
3. reproducability of soil water content (across differing soil types - to
give real differences between sites)
4. not affected by shrink-swell problems (soil moves away from sensor)
5. economy
6. standardised across the industry - and over time.
simple datalogging functions
temperature corrected - or insensitive
do not influence surroundings (no large lead wires or access tubes)
precision
accuracy
simple installation
not prone to lightning damage
low power consumption

With this [debatable] list, what sensors come to mind?
Please submit your suggestions in order of suitability.

Also, feel free to add any ommisions to he above list or to disagree with
the priority order!

Another aspect that came to mind s the depth/s of measurement, which is
stated at 1-2 m. The choice of depth must be carefully considered. At worst
it will be dictated by [shallow] soil depth. But the decision must
determined by the reason for the data collection in the first place.

Can anyone elaborate on this?
Is there a policy or project brief for this from NOAA?

Bruce

--
Bruce Metelerkamp

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