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Soil Erosion in Europe
Robert J A Jones and Luca Montanarella (editors)
Soil erosion is a natural process, occurring over geological time,
and indeed it is a process that is essential for soil formation
in the first place. With respect to soil degradation, most concerns
about erosion are related to accelerated erosion, where the natural
rate has been significantly increased mostly by human activity.
Soil erosion by water is a widespread problem throughout Europe.
The processes of soil erosion involve detachment of material by
two processes, raindrop impact and flow traction; and transported
either by saltation through the air or by overland water flow. Runoff
is the most important direct driver of severe soil erosion by water
and therefore processes that influence runoff play an important
role in any analysis of soil erosion intensity.
By removing the most fertile topsoil, erosion reduces soil productivity
and, where soils are shallow, may lead to an irreversible loss of
natural farmland. Even where soil depth is good, loss of the topsoil
is often not conspicuous but nevertheless potentially very damaging.
Severe erosion is commonly associated with the development of temporary
or permanently eroded channels or gullies that can fragment farmland.
The soil removed by runoff from the land, for example during a large
storm, accumulates below the eroded areas, in severe cases blocking
roadways or drainage channels and inundating buildings.
Erosion rate is very sensitive to both climate and land use, as
well as to detailed conservation practice at farm level. The Mediterranean
region is particularly prone to erosion because it is subject to
long dry periods followed by heavy bursts of erosive rain, falling
on steep slopes with fragile soils. This contrasts with NW Europe
where soil erosion is less because rain falling on mainly gentle
slopes is evenly distributed throughout the year and consequently,
the area affected by erosion is less extensive than in southern
Europe. However, erosion is still a serious problem in NW and central
Europe, and is on the increase. In parts of the Mediterranean region,
erosion has reached a stage of irreversibility and in some places
erosion has practically ceased because there is no more soil left.
With a very slow rate of soil formation, any soil loss of more
than 1 t ha-1yr-1 can be considered as irreversible within a time
span of 50-100 years. Losses of 20 to 40 t ha-1 in individual storms,
that may happen once every two or three years, are measured regularly
in Europe with losses of more than 100 t ha-1in extreme events.
The main causes of soil erosion are still inappropriate agricultural
practices, deforestation, overgrazing, forest fires and construction
activities.
In a period of rapid changes in both climate and land use, due
to global change, revised agricultural policies and changing international
market forces, it is vitally important to be able to assess the
state of soil erosion at a European level, using an objective methodology.
This methodology must also allow the assessment of erosion to be
repeated as conditions change, or to explore the broad scale implications
of prospective global or European-wide changes in land utilisation.
The results of applying such a methodology can provide estimates
of the overall costs attributable to erosion under present and changed
conditions, and objectively identify areas where more detailed study
is needed and possible remedial action.
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