Extended Abstract
Introduction:  Land subsidence is one of the most destructive yet hidden environmental hazards caused by various factors. In recent years, this phenomenon has become increasingly noticeable across the country. Land subsidence can result from natural processes such as tectonic and volcanic activities. However, human activities—particularly excessive groundwater extraction and the imposition of heavy loads on the earth’s surface—have recently been identified as its primary causes Moreover, climate change, reduced precipitation, and rising temperatures have decreased renewable water resources, thereby increasing reliance on groundwater and exacerbating land subsidence.
Materials and Methods: This study investigate and analyzes ground surface changes within the Marvdasht aquifer using advanced radar interferometry techniques. Initially, the Differential Interferometric Synthetic Aperture Radar (DInSAR) methodology, utilizing Sentinel-1A satellite imagery, was employed to extract the land subsidence rate from 2015–2022. Subsequently, cumulative subsidence across the entire aquifer was calculated for the study period. Additionally, average groundwater level changes during the overlapping period with interferometric data were computed to analyze the correlation between groundwater decline and land subsidence.
Results and Discussion: The results from the Marvdasht aquifer between 2015 and 2022 revealed an alarming trend of land subsidence. The highest annual subsidence rate was recorded between 2015 and 2016, reaching 24.1 cm per year, indicating the severity of the phenomenon during that period. The overall trend of subsidence over the seven years shows that, except for  2019–2020 (which experienced sharp increases in subsidence rates), the remaining years exhibited a decreasing trend. The lowest annual subsidence rate was observed in 2018–2019 at 16.3 cm.A comparison of groundwater level changes with subsidence rates during 2016–2017 and 2019–2020 indicates a significant and direct relationship. Specifically,  noticeable drops in groundwater levels coincided with  substantial rises in subsidence rates. The coefficient of determination between groundwater level changes and land subsidence was 0.26 across the entire aquifer and 0.50 in subsiding areas, indicating a relatively strong and statistically significant correlation between the two variables. This suggests a meaningful relationship between land subsidence and groundwater fluctuations in the Marvdasht aquifer. Additionally, This finding confirms the detrimental impact of excessive groundwater extraction on the intensification of land subsidence. Spatial analysis shows that the highest rates of subsidence occurs in the central and southern parts of the aquifer, areas known for a high density of groundwater extraction wells. Conversely, in urban areas of Marvdasht, where construction restrictions and extraction regulations limit the number of wells, subsidence is negligible. This findings highlight the critical importance of proper water resource management and strict monitoring of extraction activities in controlling and preventing land subsidence.
Conclusion: Land subsidence, as one of the serious environmental hazards in the Marvdasht aquifer, was investigated over the period from 2015 to 2022. The results indicate a significant relationship between groundwater level decline and the rate of land subsidence. The highest annual subsidence rate occurred during 2015–2016, reaching approximately 24.1 cm, while the lowest was recorded in 2018–2019 at 16/3 cm per year. In subsiding areas, the relationship between groundwater level changes and vertical ground displacement—considering a time lag of about two years—yielded a coefficient of determination (R²) of 0.50, statistically significant at the 5% level. Spatial analysis further revealed that the highest subsidence occurred in regions with a high density of groundwater extraction wells (central and southern parts of the aquifer), while minimal subsidence was observed in areas with low well density (northeastern and southeastern regions). This underscores the substantial role of excessive groundwater withdrawal in driving land subsidence in the region. Ultimately, this study emphasizes the urgent need for sustainable groundwater management. Recommended strategies include controlling over-extraction through the installation of smart water meters, implementing artificial recharge programs, improving irrigation efficiency, developing land subsidence risk zoning plans, and enhancing public awareness and education for groundwater users. These measures can significantly contribute to reducing subsidence rates and mitigating associated risks.