Sinkholes and subsidence in Lar dam, Northeast of Tehran: result from imaging geodesy

In this study, sinkholes and subsidence around Lar dam, NE Tehranare investigated using multi-temporal C-band and L-band SAR images from ENVISAT and ALOS PALSAR satellites. The Lar dam has been constructed to supply drinkable water for Tehran, the capital city of Iran. According to the geological map the region is mainly made of a series of karstic limestone, which makes it very vulnerable to subsidence. This has led tothe production of karst and sinkholes in the limestone below the dam. Moreover acidic ground-water run-off the Damavand volcano has increased the dissolution of the carbonate beds along the fractures, in turn contributing furtherto the development of sinkholes in the dam area.In this regard ten sinkholes were observed in the area and within few kilometers away from the dam location on the upstream side. In this research we evaluated the effectiveness of Interferometric Synthetic Aperture Radar (InSAR) time-series method in monitoring sinkhole-related subsidence around the LAR dam regions. We show that the use of SAR data makes the long term monitoring of subsidence much more efficient as compared traditional surveying techniques such as micro-geodesy and classical leveling.

کلیدواژه ها:

Subsidence ، Lar dam ، Sinkhole ، InSAR