Application of GPS for Monitoring Land Subsidence

Abstract

Monitoring land subsidence due to various causes is a challenging task in Geodesy. This paper deals with the monitoring land subsidence with Global Positioning System (GPS) in the South Gujarat, India. In this area, hydrocarbon is being extracted since many years. Hydrocarbon production is one of the main causes of land subsidence over the study area. Land subsidence studies have been carried out by GPS team, Indian Institute of Technology, Bombay with dual frequency GPS receivers. Total nine field campaigns have been completed. The collected GPS data have been processed in post processing mode using scientific GPS data processing software using precise ephemeris. To achieve mm level accuracy, ionospheric correction and tropospheric corrections were estimated and applied during data processing. Statistical testing was done to check the significance of the GPS data. The results of statistical testing confirm that there is significant subsidence within the reservoir boundary than the subsidence outside the reservoir boundary. It is established that gas extraction is one of main causes of subsidence over the study area. In this paper the findings of nine GPS campaigns are depicted.