Mehran Fatemi; Atefeh Jebali; Asghar Zare Chahouki
Abstract
Salt playas in arid regions are unique and sensitive ecosystems, playing a crucial role in environmental balance and ecological sustainability. This study aimed to evaluate the geomorphological change trends in the Abarkouh salt playa by employing advanced remote sensing techniques within the Google ...
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Salt playas in arid regions are unique and sensitive ecosystems, playing a crucial role in environmental balance and ecological sustainability. This study aimed to evaluate the geomorphological change trends in the Abarkouh salt playa by employing advanced remote sensing techniques within the Google Earth Engine (GEE) platform. The research monitored geomorphological facies and environmental changes in the playa from 2002 to 2024 using Landsat 5 and 8 satellite imagery. Spectral indices for vegetation (NDVI, SAVI, EVI, and TSAVI), water (MNDWI), soil moisture (NDMI), and soil salinity (SI) were analyzed to assess these changes. The results reveal substantial geomorphological alterations in the playa over the study period. Specifically, water bodies and vegetation cover decreased by approximately 65% and 51%, respectively, from the initial year, while saline, clay, and sandy lands expanded by about 23%, 66%, and 103%. Spectral index analyses further indicated a significant decline in water levels and a significant rise in soil salinity, both at the 1% and 5% significance levels, respectively. Notably, a key finding of this study is the contradiction between the spectral indices and the classification maps. Despite a significant upward trend in all vegetation indices, the classification maps consistently showed a decrease in vegetation cover. This discrepancy highlights that in this arid environment, the vegetation indices are influenced by the spectral reflectance of salt and gypsum rather than actual vegetation, leading to a false positive signal. The study concludes that the boundaries of geomorphological facies within the Abarkouh salt playa have undergone significant changes, largely driven by drought and human activities.
