Determination of the relationship between land subsidence and ground water level loss with radar interferometry and GPS station methods (Case study: Salmas Plain)

Salmas plain is one of the most important plain in the western Azerbaijan province. In the last decades, speedy population growth coupled with agricultural expansion has extremely increased pressure on the groundwater resources. Irregular increases in water demand and a little recharge ground water have caused to decline in water level in the plain in recent decade. As a result of declining in groundwater levels, land subsidence appears in some parts of plain. In this study, the relationship between the decline in groundwater levels and land subsidence was examined. The land subsidence survey methods were permanent GPS observations and Radar interferometry. The results showed high and linear correlation between the decline in groundwater levels and land subsidence in this plain. The average determination coefficient for GPS and Radar interferometry methods were obtained 78% and 82%, respectively. Maximum rate of subsidence was calculated 11 cm/year using ALOS satellite radar images in 2009. The results of GPS method indicated that one meter decline in groundwater level will be caused 0.078 m land subsidence in the plain studied.