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Soil moisture is an important indicator, as it plays a role
in the phenomena that affect vegetation and the hydrological cycle.
In alpine environments, which are more prone to climate change,
soil moisture is definitely a very important parameter.
We measure it in two ways:
the first is with satellites,
that capture digital images of the area;
the other is with ground data.
We are carrying out ground truth measurements in Val di Mazia
because later on today there will be a fly-over of
a satellite called Radarsat2, which will acquire data from this area.
It is important for us to have a matching reference on the ground.
The satellite works with microwaves, using the same
principle as a microwave oven- it very sensitive to water content.
The greater the amount of water we have in the soil, the greater the
sensor's response, so we need ground measurements to
compare the sensor's readings with the ground value of soil moisture
In this way we can transform the maps that satellites give us
into soil moisture maps, not with so many points, but we will have a map
distributed throughout the area of Val di Mazia of soil moisture.
In our measurement campaigns
we monitor the wettest and the driest locations
in swaths that we establish from
the map that the satellite provides us with.
In particular, we measure the differences between drier grazing areas
and irrigated meadows areas.
You can see in the landscape that surrounds us
that irrigated lawns are a very bright green
while the dry grass pastures are more yellow.
With the satellite we can see this contrast, and thanks to our
ground measurements we can calibrate what the satellite sees
To measure soil moisture we use two different techniques:
the first technique is an indirect method
based on the measurement of the electrical conductivity of the soil;
we use these mobile soil moisture sensors,
insert them into the ground
and measure the change in the electrical conductivity
of the soil,
which changes according to the water content in the ground.
The second technique that we use to measure soil moisture
is to take
soil samples and measure
their water content.
in the laboratory.
To do this we insert metal cylinders
into the ground,
and store the contents of the cylinder
so as not to lose any moisture
Then we bring these samples in our laboratory where
they are weighed, and then placed into an oven.
When they dry out, we weigh them again,
and the difference in mass between the dry and the wet samples
represents the moisture content.
With this measurement, we can derive the volumetric content
This is by far the most accurate method, but it is very expensive.
So we have to limit the number of samples, and choose a
limited number of representative samples.
Combining the ground measurements
with satellite data,
we obtain GIS maps of soil moisture
These maps show how the soil moisture
varies in space and time.
This can help farmers understand the state of their
pastures or orchards,
and can help in civil defence,
for the prevention of natural hazards such as
landslides and floods.
The data can also be inserted into hydrological models
to calculate the water balance of the whole valley
These models,
when used in combination with data coming from
climate models showing future
may be useful for understanding the water resources availability
in future years in the Val Venosta.