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Dune morphology

Sand dunes of Gavkhouni (Varzaneh Erg) are active and semi – active dunes in the southeast of Isfahan province and west of Gavkhouni international wetland. They play key role in increasing dust storms and causing damages to roads in the region. In this study, sand dunes changes were detected using satellite MSS, TM, ETM+ and LISS III images during 32 years. In pre-processing stage, all images were geometrically registered with RMS error less than one pixel. Land use/cover maps of the region were produced using image processing techniques includingprinciple component analysis,false color composite,NDVI vegetation index and supervised classification applying maximum likelihood classifier. The accuracy assessment of the classified maps indicated that there was more than 89% agreement between the satellite and field data. Comparison of spatial distribution of sand dunes of different times using post classification method, revealed that the area of sand duneshas been increased about 5086 ha (from 14475 to 19561ha) in past three decades. This increase was observed in the inter-dune areas and mostly in central and southern section of the Erg.