Multi-Temporal InSAR Analysis of Urban Land Subsidence in Tashkent City, Uzbekistan Using Sentinel-1 SAR

Land subsidence represents a growing hazard in urban areas, yet Central Asian cities remain among the least systematically monitored despite recent global assessments identifying Uzbekistan as one of the countries with the highest mean subsidence rates.Tashkent city, one of Central Asia's largest cities, is built on Quaternary alluvium and relies on an aquifer system, yet no dedicated multi-temporal Interferometric Synthetic Aperture Radar (InSAR) assessment has been reported.This study characterizes urban land subsidence across Tashkent city using Sentinel-1A spanning from March 2017 to December 2023.The resulting mean line-of-sight (LOS) velocity shows that most of the city is stable, with mean velocity between -3 and +3 mm/year, with deformation confined to discrete, compact zones in the southeastern, southern, and northern parts of the city rather than forming a single continuous subsidence bowl.Within these zones, LOS displacement is predominantly -6 to -9 mm/yr, with maximum clusters exceeding -12 mm/yr.Assuming purely vertical motion, the vertical component of linear velocity was computed from four representative sites and yielded linear rates of -7.6 to -11.1 mm/year, with the highest subsidence located in the southeastern industrial zone.Internal precision assessment indicates a formal velocity uncertainty (1-sigma) of about 0.4 mm/year over approximately 98% of the study area, and comparison with the continuous Global Navigation Satellite System (GNSS) station, TASH, shows a LOS velocity difference of 0.99 mm/year and a coefficient of determination of 0.694.The spatial coincidence of the deformation zones with industrial and dense residential areas suggests localized groundwater abstraction and consolidation under structural loading as the most plausible drivers.The results provide, to our knowledge, the first dedicated land subsidence baseline for Tashkent city and demonstrate a transferable, low-cost monitoring capability for other Central Asian cities with sparse insitu geodetic infrastructure.

Hali tarjima qilinmagan