Yaser GHasemi Arian; Hadi Eskandari Dam aneh; Maryam Naeimi; Adel Jalili; Samira Zandifar; Azadeh Gohardoust; Sakineh Lotfinasabasl
Volume 32, Issue 1 , May 2025, , Pages 1-17
Abstract
Background and objectivesLand subsidence, primarily caused by excessive groundwater extraction, constitutes the most advanced and irreversible stage of desertification and land degradation. While this phenomenon poses a significant threat to numerous plains and major urban centers across Iran, existing ...
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Background and objectivesLand subsidence, primarily caused by excessive groundwater extraction, constitutes the most advanced and irreversible stage of desertification and land degradation. While this phenomenon poses a significant threat to numerous plains and major urban centers across Iran, existing desertification assessment models have largely overlooked subsidence rates and the agricultural sector's substantial groundwater consumption. This study evaluates desertification intensity in the Qaraqom basin through the dual lenses of water resource utilization and land subsidence dynamics.MethodologyThe study employed the Inverse Distance Weighting (IDW) method in GIS 10.8 to create zonation maps for three critical groundwater indices: electrical conductivity (EC), sodium adsorption ratio (SAR), and groundwater level decline. Data from 273 observation wells (2001-2018) were classified into four desertification intensity categories (low, moderate, severe, and very severe). These maps were integrated with a land subsidence rate map (2015-2016 water year) derived from Sentinel-1 satellite imagery provided by the Geological Survey of Iran. Additionally, reservoir volume changes (1985-2018) were analyzed for each aquifer to assess their relationship with subsidence patterns.ResultsAnalysis revealed severe to very severe desertification across 46.6% of the basin based on EC values, while SAR indicated low degradation in 90.6% of the area. Groundwater depletion showed the most critical conditions, with 53.4% of the basin experiencing severe to very severe impacts, particularly in the Sarakhs, Fariman-Torbat Jam, southwest Mashhad, and Narimani aquifers. Subsidence rates reached severe levels in 18.1% of the basin, with maximum values observed in the Mashhad, Fariman-Torbat Jam, Taybad, and Karat aquifers. The Mashhad aquifer demonstrated the highest subsidence rates and the most significant reservoir volume changes. Integrated assessment of groundwater and subsidence criteria classified 55.9% of the Qara Qom watershed as moderately affected and 26.1% as low-intensity desertification.ConclusionAs agriculture represents the dominant water consumer in the basin, immediate implementation of water efficiency and productivity measures in this sector is crucial to prevent irreversible socio-economic and ecological consequences of ongoing desertification and land degradation.