بررسی تغییرات اپتیکی و بیوفیزیکی سطح زمین طی وقوع یک طوفان در منطقه خشک ( مطالعه موردی: جنوب شرق اصفهان و پلایای گاوخونی)

Studying the variations of energy balance and surface temperature, vegetation and spectral reflectance of geomorphological features during the catastrophic processes such as storms and environmental hazards on a large scale requires powerful tools such as thermal remote sensing. This research has considered the effective use of remote sensing methods by such practical approach. The study area is located in the southeast area of Isfahan province and Gavkhuni Playa Lake that is remarkable from the viewpoint of diversity of geomorphological features in arid and desert regions. In this study, variations of surface albedo, emissivity, and land surface temperature, water vapor, vegetation index and reflectance of geomorphological features and land use before and after the storm was investigated by MODIS satellite images. The result showed that the dust storm, has increased land surface temperature and has intensified dry condition of soil, also in a short time has had a negative impact on the vegetation index. T-test rejects assuming equal means in condition before and after the storm therefore the storm has had significant influences on the parameters that have been studied. The severity of these changes has been distinct according to land use and geomorphological features and devoid of vegetation areas such as Playa, desert and sand dunes have had the most variations. Variations in spectral reflectance of land surface were considered by standardized differences map and results showed that Gavkhuuni Playa Lake has had the most variations and has been the source of deflation by strong winds. In addition, investigation of the aspect of slope map and topography map showed the eastern and northeastern slopes have had more variations compared to the western and south-western slopes.