Characterization of Irreversible Land Subsidence in the Yazd-Ardakan
Plain, Iran from 2003-2020 InSAR Time Series
Abstract
Groundwater extraction at rates exceeding recharge is occurring
throughout Iran for agricultural and industrial activities, resulting in
land subsidence in many areas, particularly the Yazd-Ardakan Plain (YAP)
in the dry and desert regions of central Iran. In this study,
Interferometric Synthetic Aperture Radar (InSAR) time series analysis
and statistical models are used to characterize the controls on land
subsidence in the YAP, from 2003 to 2020. Our results reveal the
existence of a northwest-southeast elongated area of 363 experiencing
subsidence at rates up to 15 cm/yr. In the YAP, the international
Airport, railway, transit road, and several industrial and historical
sites are threatened by the differential subsidence. Well data confirm
that groundwater levels have decreased by 18 meters between 1974 and
2018, driving the compaction of sediments within the underlying aquifer
system. Our statistical analysis shows that the thickness of a shallow,
clay-rich aquitard layer controls the extent of the observed subsidence
and an Independent Component Analysis of the InSAR time series shows
that inelastic compaction dominates. This work reveals that in central
Iran, current groundwater extraction practices are not sustainable and
result in permanent subsidence, ground fractures with impact on
infrastructures, and a permanent decrease in water storage capacity.