Surface deformation detection and attribution in the Mountain-Oasis-Desert Landscape in north Tianshan Mountains

ABSTRACT

The Mountain-Oasis-Desert System (MODS) is the fundamental landscape component within the vast arid region of Central Asia. Human activities and natural processes cause surface displacement in the MODS, resulting in geoenvironmental issues and hazards. However, surface displacement and its driving mechanisms in the MODS are not understood. In this study, we used the time-series interferometric synthetic aperture radar (InSAR) method to detect deformation in the MODS in north Tianshan Mountain, Xinjiang and investigated its attribution from the geological conditions, groundwater level changes, and climate variability. The results along the vertical gradient indicate that decorrelation is severe in the high mountain areas with ice-marginal environments (over 3600 m above sea level (a.s.l.)) and the forest-covered mid-mountainous belt (1700–2800 m asl), rendering effective detection unfeasible. Dynamic characteristics are identified in subalpine areas with an elevation of 2800–3600 m asl, with maximum horizontal and vertical displacements of −80.2 mm/year and −58.6 mm/year, respectively. The seasonal acceleration is influenced by the combined effects of temperature and precipitation changes. We observed dense subsidence funnels and ground fissures associated with coal mining in the foreland hills (700–1700 m asl). Ground displacements here exceeded −50 mm/year two years after mining activities had ceased. Subsidence has expanded in the oases with elevations of less than 700 m asl, due to extensive groundwater extraction for agricultural irrigation. The correlation coefficient between groundwater level and displacement was 0.89 and 0.45 at wells in the agricultural and desert areas, respectively. The deformation exhibited seasonal variations associated with groundwater level. The deformation remains relatively stable in the surrounding oasis-affected desert areas, with weak fluctuations influenced by seasonal variations in groundwater level.

KEYWORDS:

• Mountain-Oasis-Desert
• InSAR
• deformation
• mining
• groundwater level

Acknowledgments

We would like to thank Dr. Daniel Petticord at the University of Cornell for his assistance with English language and grammatical editing of this manuscript. This research was supported by The Third Xinjiang Scientific Expedition Program (Grant No. 2021×jkk0903) and the High-End Foreign Experts Project (Grant No. E0600101). The authors express their gratitude to the European Space Agency (ESA) for providing unrestricted access to Sentinel-1 data and to the Japan Aerospace Exploration Agency (JAXA) for providing ALOS-1/PALSAR images. Both the ALOS-1/PALSAR images and the Sentinel-1 data were downloaded from the Alaska Satellite Facility (ASF).

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

Data used in this study is available upon reasonable request to the first author Binbin Fan ([email protected])

Additional information

Funding

The work was supported by The Third Xinjiang Scientific Expedition Program [2021×jkk0903]; the High-End Foreign Experts Project [E0600101].