Atefe Choopani, - Graduated in Remote Sensing from the Dept. of Civil and Environmental Engineering, School of Engineering, Shiraz University, Iran
Maryam Dehghani, - Associate Prof. of the Dept. of Civil and Environmental Engineering, School of Engineering, Shiraz University, Iran
Mohammad Reza Nikoo - Associate Prof. of the Dept. of Civil and Environmental Engineering, School of Engineering, Shiraz University, Iran

Despite the fact that about 1.7 percent of total water on the earth is groundwater, it is one of the most essential resources for agriculture, manufacturing and drinking applications. Excessive extraction of groundwater resources for irrigation of pistachio gardens has resulted a significant subsidence in Sirjan Basin, Kerman, Iran. Subsidence phenomena can pose a threat to the security of people and governments. Subsidence not only threatens stability and strength of man-made structures, but also decreases significantly the aquifer capacity to store water. In this study, Interferometric Synthetic Aperture Radar (InSAR) technique is used to estimate deformation time series in two different periods from 2004 to 2010 and during 2017 using both ENVISAT ASAR and Sentinel-1 radar imageries. The Small Baseline Subset (SBAS) time series analysis in which the processed interferograms are characterized by small spatial and temporal baselines are employed. There are 12 ENVISAT ASAR images and 9 Sentinel-1 images from the descending orbit. Two different subsidence velocity maps are calculated based on two datasets. The maximum subsidence rate obtained from ENVISAT ASAR data is estimated as 28 cm/yr while this is 17 cm/yr for the Sentinel-1 data. Comparing two displacement time series results, it is found that surface displacement rate in 2017 has been decreased in some places compared to that one obtained in the ENVISAT ASAR acquisition period probably due to less over-exploitation of groundwater. Moreover, the spatial pattern of the subsidence indicates that a significant part of residential areas suffers from high-rate deformation which may be a cause for concern.

Groundwater Resources, InSAR, Sirjan Plain, Subsidence, Time Series Analysis