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| Titel |
Wind erosion in the alpine zone - a case study at Latschuelfurgga (Davos, Switzerland) |
| VerfasserIn |
F. Graf, Ch. Gromke |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250062377
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| Zusammenfassung |
| Protection against wind erosive processes ranks among the most important challenges
in natural hazard mitigation, worldwide. Today, it is generally accepted that the
(re-)establishment of a protective vegetation cover is the most promising and efficient
measure in restoring degraded land in the long term. Sustainable protection against wind
erosion requires adequate information about suitable plant species regarding ecological
aspects as well as with respect to their proper contribution to wind erosion control.
The latter, however, is widely lacking. Within a broader conceptual framework,
wind tunnel studies have been performed using naturally grown vegetation covers.
The use of live plants aimed at simulating the behaviour of natural canopies as
accurately as possible compared to previous studies using artificial objects. The
goals of the presented field study are to record reliable data on windblown erosion
rates under natural alpine conditions on the one hand and, on the other hand, to
interrelate the findings with the results of the wind tunnel experiments with live
plants.
The wind erosion test field was established at 2409 m a.s.l. on a small saddle
like pass in an alpine meadow and includes two east-west orientated test tracks of
the dimension 2x10 m2. One track is left as is, representing the naturally alpine
vegetated soil (15-20% plant cover). The other track is equipped with a plastic covering
sheet, mimicking desertified soil (0% plant cover) and serving as control plot as
well as providing a direct link to the wind tunnel experiments. Blue and red quartz
sand (grain size: 0.2-0.6 mm) was spread on the vegetated and sheet-covered track,
respectively, to visualise and measure the effect of vegetation on wind erosion control.
During summer and fall 2010 field experiments were performed of which experiment
no. 4 is presented here as a case study as well as compared with and discussed
in relation to a wind tunnel run with medium-density configuration (16% plant
cover).
The measuring equipment consists of three climate stations recording wind direction and
wind speed at 50, 100, and 200 cm, air temperature and humidity, incoming and reflected
short- and long wave radiation, as well as precipitation. Leeward of the two test tracks, panels
and ground-plates were installed equipped with sticky foils to trap and quantify vertical and
horizontal particle transport.
Compared to the desertified soil (0% plant cover) it was found that only small amounts of
sand from the vegetated plot (15-20% plant cover) were transported, even during heavy wind
events. Overall the ratio varied from 1:50 to 1:175 depending on the position of the
panels and ground plates. Qualitatively similar findings, however quantitatively less
pronounced, resulted from the wind tunnel experiments (ratio = 1:15). The difference
between the field study and the wind tunnel results is quite remarkable and implies
that the sheltering effect of vegetation under natural conditions is 3 to 12 times
higher than found for the medium-density experiment in the wind tunnel (16% plant
cover).
However, this conclusion needs careful reflection. After all, the two studies differ in
several aspects of their set-up. Correspondingly, the data are speculatively discussed,
particularly with respect to meteorological parameters (wind speed, turbulence
intensity, humidity, temperature), ecological aspects, and hydrological processes. |
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