Understanding Land Subsidence Along the Coastal Areas of Guangdong, China, by Analyzing Multi-Track MTInSAR Data

Abstract

Coastal areas are usually densely populated, economically developed, ecologically dense, and subject to a phenomenon that is becoming increasingly serious, land subsidence. Land subsidence can accelerate the increase in relative sea level, lead to a series of potential hazards, and threaten the stability of the ecological environment and human lives. In this paper, we adopted two commonly used multi-temporal interferometric synthetic aperture radar (MTInSAR) techniques, Small baseline subset (SBAS) and Temporarily coherent point (TCP) InSAR, to monitor the land subsidence along the entire coastline of Guangdong Province. The long-wavelength L-band ALOS/PALSAR-1 dataset collected from 2007 to 2011 is used to generate the average deformation velocity and deformation time series. Linear subsidence rates over 150 mm/yr are observed in the Chaoshan Plain. The spatiotemporal characteristics are analyzed and then compared with land use and geology to infer potential causes of the land subsidence. The results show that (1) subsidence with notable rates (>20 mm/yr) mainly occurs in areas of aquaculture, followed by urban, agricultural, and forest areas, with percentages of 40.8%, 37.1%, 21.5%, and 0.6%, respectively; (2) subsidence is mainly concentrated in the compressible Holocene deposits, and clearly associated with the thickness of the deposits; and (3) groundwater exploitation for aquaculture and agricultural use outside city areas is probably the main cause of subsidence along these coastal areas.

Benefits of subsidence control for coastal flooding in China

“…The impacts assessed in this study only consider the flood impacts of land subsidence, ignoring other damages that might occur, such as building collapse, and the formation of local subsidence bowls, ground cracks or fissures 17,34 . Subsidence can also lead to saline intrusion and waterlogging, impacting water quality, ecosystem services and agriculture 35,36 .…”

Satellite‐Observed Decreases in Water Turbidity in the Pearl River Estuary: Potential Linkage With Sea‐Level Rise

“…Finally, the water turbidity declined in the Pearl River Estuary. Simultaneously, groundwater exploitation for aqueous, agricultural, and urbanization use has caused severe land subsidence that could accelerate the sea-level rise in this area (Du et al, 2020). Since sand dredging and land subsidence probably occur in the same period, it is not surprising that the water turbidity and the sea-level showed good correlations.…”

Understanding the Spatial-Temporal Characteristics of Land Subsidence in Shenzhen under Rapid Urbanization Based on MT-InSAR

“…However, the current situation of land subsidence in China deteriorates with urbanization progress, especially in cities with rapid urbanization. Additionally, in addition to land subsidence, other secondary disasters, such as sinkholes [3], urban flooding [4], infrastructure damage [5], and seawater intrusion in coastal areas [6,7], can threaten people's lives and the normal operation of cities. Specific to the city of Shenzhen, it has undergone tremendous urbanization with the rapid development of the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) in the past few decades [8].…”