Monitoring ground displacement of Warri metropolis using persistent scatterer interferometry (PSI) and small baseline subset (SBAS) time series

Abstract

Ground subsidence is a major challenge faced by many cities worldwide, with infrastructure
damage costing billions annually. This study aims to retrieve the subsidence of Warri, a coastal
city in Southern Nigeria, using interferometry synthetic aperture radar (InSAR). Persistent
Scatterer Interferometry (PSI) and Small Baseline Subset (SBAS) methods were used for the
retrieval of the subsidence in the city. Results obtained show that Warri experiences
subsidence, with PSI revealing a displacement of -0.5 to 1.5 mm/year, and SBAS showing 0.33
to 0.65 cm/year. The standard deviation for PSI ranges between 0.7 and 7.8 mm/year, and 0.2
to 1 cm/year for SBAS. Our study highlights the exceptional capabilities of InSAR in effectively
and precisely monitoring subsidence across extensive urban regions, achieving remarkable
accuracy down to millimetre scale.