Dust Source Dynamics in Arid Iran: Examining the Relationship between MODIS AOD and Land Surface Characteristics in a Dried Catchment

Abstract

Dust sources are expanding unprecedentedly across the arid parts of Iran. To quantify this trend in the Kaftar Catchment in SW Iran (5,600 km2), the MODIS AOD product “Optical_Depth_047”, accessible through Google Earth Engine was utilized, as one of the moderate-resolution (1km) aerosol data sources spanning from 2002 to 2023. The layers were preprocessed and averaged to derive annual mean data (AM-AOD), and its accuracy was verified using reference dust data collected from 24 stations in 2022 (correlation coefficient = 0.565; p-value < 0.01). The Mann-Kendall trend test confirmed a statistically significant upward trend in AOD values. A positive Sen’s slope predominated for the majority of the AM-AOD pixels. The Generalized Additive Model (mean R2 = 0.753) successfully predicted AM-AOD values at each pixel for the year 2035. According to the Landsat 8-derived LULC map of the region (Kappa = 83.56), the wetland area is projected to experience the highest increase in AM-AOD in 2035, reaching 0.43 ± 0.06, while rangelands are expected to observe the lowest increment at 0.17 ± 0.07. Our study underscores the urgency of rehabilitating the Kaftar Wetland, promoting low-water crops, and improving ecosystem resilience in rangelands.