Monitoring Sand Dunes Changes of Gavkhouni International Wetland Using Satellite Imagery

Sand dunes of Gavkhouni (Varzaneh Erg) are active and semi-active ones 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 have been detected using satellite MSS, TM, ETM and LISS III images during a 32 year period. In pre-processing stage, all images were geometrically registered with RMS error of less than one pixel. Land use/cover maps of the region were produced using image processing techniques including principle 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 were more than 89% agreements between the satellite and field data. Comparison of spatial distribution of sand dunes in different times using post classification method, revealed that the area of sand dunes has been increased to nearly 5086 ha (from 14475 to 19561ha) in past three decades. This increasing has been observed in the inter-dune areas, mostly in central and southern sections of the Erg.