Detecting and Analyzing the Evolution of Subsidence Due to Coal Fires in Jharia Coalfield, India Using Sentinel-1 SAR Data

Moidu Jameela Riyas,Claudia Kuenzer,Tajdarul Hassan Syed,Hrishikesh Kumar

doi:10.3390/rs13081521

Abstract

Public safety and socio-economic development of the Jharia coalfield (JCF) in India is critically dependent on precise monitoring and comprehensive understanding of coal fires, which have been burning underneath for more than a century. This study utilizes New-Small BAseline Subset (N-SBAS) technique to compute surface deformation time series for 2017–2020 to characterize the spatiotemporal dynamics of coal fires in JCF. The line-of-sight (LOS) surface deformation estimated from ascending and descending Sentinel-1 SAR data are subsequently decomposed to derive precise vertical subsidence estimates. The most prominent subsidence (~22 cm) is observed in Kusunda colliery. The subsidence regions also correspond well with the Landsat-8 based thermal anomaly map and field evidence. Subsequently, the vertical surface deformation time-series is analyzed to characterize temporal variations within the 9.5 km2 area of coal fires. Results reveal that nearly 10% of the coal fire area is newly formed, while 73% persisted throughout the study period. Vulnerability analyses performed in terms of the susceptibility of the population to land surface collapse demonstrate that Tisra, Chhatatanr, and Sijua are the most vulnerable towns. Our results provide critical information for developing early warning systems and remediation strategies.

Highlights

Published: 15 April 2021Subsurface coal fires constitute a significant socio-economic and environmental threat in at least 30 countries worldwide [1,2,3]
Even if some of the sudden changes are recorded in Interferometric Synthetic Aperture Radar (InSAR), they will be omitted while performing jump-corrections in the subsidence time-series
While proving the effectiveness of New-Small BAseline Subset (N-Small BAseline Subset (SBAS)) technique for coal fire mapping, it correlates well with the 9.07 km2 of coal fire regions derived from Landsat8 thermal infrared (TIR) image using the thresholding technique

Summary

Introduction

Published: 15 April 2021Subsurface coal fires constitute a significant socio-economic and environmental threat in at least 30 countries worldwide [1,2,3]. Coal fire produces abundant toxic gases such as nitrogen oxides (NOx ), sulfur dioxide (SO2 ), carbon oxides (COx ), nitrous oxide (N2 O), and methane (CH4 ) continuously, which act as greenhouse gases [5,6,7,8]. While these gases cause severe respiratory and coronary diseases, thousands of people die by coming in direct contact with coal fires and coal fire-triggered explosions in mining environments [9]. Associated with land subsidence are the formation of deep cracks

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