Vaisala WMS302 Betriebsanweisung PDF herunterladen (Seite 55)

Chapter 3 _________________________________________________________ Selecting Location

VAISALA_______________________________________________________________________ 53

- Earth worm holes or mole holes

- Subsoil drainage

- Small scale variability in transpiration and evaporation losses.

It is important to take the degree of variability of these parameters into

account when deciding on the number of probes to be used at any

particular location. If the soil is known to be very heterogeneous, it will

be necessary to take measurements from at least three closely-spaced

locations.

Soil Moisture Sensor

Finding a suitable site for the product is important for getting

representative ambient measurements. The site should represent the

general area of interest.

When selecting a site for ECH

O-M3 installation, it is important to

remember that the soil adjacent to the probe surface has the strongest

influence on the probe reading and that the probe measures the

volumetric water content. Therefore any air gaps or excessive soil

compaction around the probe can profoundly influence the readings.

Also, do not install the probes adjacent to large metal objects such as

metal poles or stakes. This can attenuate the probe’s electromagnetic

field and adversely affect output readings.

Submersible Water Level Sensor

Finding a suitable site for the product is important for getting

representative ambient measurements. The sensor should always be

protected against the flow and impurities in the river. Typically, the

water level sensor is installed in a stilling well or inside a pipe for

protecting the sensor against debris and vandalism.

Place the sensor according to the following examples. Refer to Figure

37 on page 54.

Example 1: Average water level is 25 meters (82 ft.) and maximum

annual change is 50 cm (19.7 in.). Suitable sensor is with range of 75

cm (29.5 in.) and installation place is 24,6 meter (80.7 ft.) from ground

level.

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Vaisala WMS302 Betriebsanweisung Seite 55