A Wind Erosion Case Study in an Alpine Environment (Davos, Switzerland) Compared to Wind Tunnel Experiments with Live Plants

Frank Graf

Abstract


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. The goals of the presented field study are to record reliable data on windblown erosion rates under natural alpine conditions and to cross-link the findings with the results of wind tunnel experiments. A wind erosion test field was established at 2409 m a.s.l. in an alpine meadow including two test tracks. One track is left as is, representing the naturally alpine vegetated soil (10-20% plant cover). The other track is equipped with a plastic covering sheet, mimicking desertified soil (0% plant cover). Blue and red quartz sand was spread on the vegetated and sheet-covered track, respectively, to visualise and measure the effect of vegetation on wind erosion control. Compared to the bare soil it was found that only small amounts of sand from the vegetated plot were transported, even during heavy wind events. Related to the seasonal course, the overall ratio varied from 1:19 to 1:717. Qualitatively similar findings, however quantitatively less pronounced, resulted from the wind tunnel experiments (ratio = 1:15). Under consideration of all available information, the comparison with data from the field experiment considering only the configuration that best coincide with the wind tunnel set-up yields at least a 70-fold higher impact of plants on wind erosion control under natural conditions. The difference implies that the sheltering effect of vegetation in nature is much higher than found for wind tunnel runs, even when using live plants.

Keywords


Land Degradation;

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References


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