Landscape scale measurements of wind erosion of volcanic materials in the Hekla area

Wind erosion is one of the principal factors responsible for desertification. Due to volcanic activity, harsh climate and unsustainable land use, Iceland has extensive desert areas where wind erosion in common. The objectives of the present study were to i) measure aeolian sand transport on a landscape scale, ii) to estimate the effect of environmental factors on sand transport and iii) estimate the effect of reclamation efforts on wind erosion. The research area, north of Hekla in South Iceland, extends approximately 110 km2 of barren or sparsely vegetated land, with sandy lava fields and sand and pumice fields dominating the surface. Wind erosion was studied for two summers, 2008-2009, on a landscape scale, by measuring the actual aeolian sand transport during erosion events with dust traps at 32 locations. Electronic sensors, meteorological data, field mapping, remote sensing and GIS analysis were also used to measure sand transport and estimate the effect of reclamation efforts and environmental factors on wind erosion. The aeolian sand transport ranged from negligible to approximately 150 kg m-1 hr-1 at locations with the most intensive erosion. At some of the most active aeolian transport sites the mass sand transport was >1 t m-1 per summer and at one location it was almost 3 t m-1 during the summer of 2008. There are interactions between aeolian and fluvial processes within the research area. The most active erosion areas are in the northeast, fed by aeolian sediment sources, but an active pathway for aeolian sand movement runs through the research area from the north-eastern part, along the hillsides of Valafell and then into the Þjórsá river, mostly along a major seasonally active waterway. Therefore, both aeolian and fluvial sediment sources affect the erosion intensity. Environmental factors considerably affect the wind erosion and my conclusion is that field mapping of surface characteristic can be used to estimate erosion susceptibility. Image classification and spatial analysis based on field mapping were used to transform data on sand movement from dust traps onto landscape scale measurements. A better correlation with the aeolian sand transport was gained by using spatial analysis based on field mapping attributes, with r2 of 0.70, compared to r2 as 0.65 using the image classification where reference sites were chosen based on knowledge from field mapping. The surface characteristics that mostly affect the erosion susceptibility are: amount of loose materials on surface, vegetation cover, grain size and rock outcrop. Measurements on the effect of reclamation efforts on wind erosion show that vegetation cover in reclamation areas has detrimental effect on the sand transport, and wind erosion is greater by an order of magnitude outside reclamation areas compared to wind erosion within them.

Author dc:creator

• Elín Fjóla Þórarinsdóttir 1967-

Contributors dc:contributor

• Landbúnaðarháskóli Íslands

• Heklugos
• Vindrof
• Vatnsrof
• Umhverfisþærttir
• Uppgræðsla

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/1946/7340

OAI identifier oai:identifier

oai:skemman.is:1946/7340