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Change detection is a basic requirement in management and evaluation of natural resources. Landuse change map which is the result of land change processes can be obtained from multi-temporal images.Various techniques have been presented for landuse/lancover change detection. In this study, images of landsat TM) 1988 and landsat (ETM+) 2001 were analyzed using 4 change detection techniques in 80470 hectares in Daresher region, Ilam Province. Change detection techniques considered were standardized and non-standardized principal component analysis (PCA) differencing, applying Canonical component analysis (CCA) differencing and Tasselled Cap (KT) differencing that all are in transformation group. Since these methods require determining threshold, therefor, statistical methods for determining the threshold level was used being achieved from the change threshold. In this study, threshold level was set at ±1 standard deviation from the mean. After determing optimal threshold, areas having decreasing change increasing change and no change were determined. Based on ground data and field work, aerial photo of 1:20000 and Google Earth, accuracy assessment of change detection techniques was carried out using overall accuracy and Kappa coefficient. According to the results, PC1difference image of CCA transform with overall accuracy of 98 and Kappa coefficient of 0.97 showed the largest accuracy among applied change detetion techniques in the Daresher region

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Monitoring of Dupiagh landslide in the Ahar-chaiy basin based on PSInSAR method of RADAR Interferometry and GPS
Introduction
Landslides are one of the most common and dangerous threats in the world that generate considerable damage and economic losses. Landslides detection and monitoring are two important research aspects of landslides analysis. There are different geodetic and non-geodetic methods to measure slope instability. Geodetic methods includes ground observations via GPS, Total Station and laser scanners. Observation based on mentioned methods provide accurate and continuous measurements at limited points in unstable regions, but none of them has the ability to determine the extent and pattern of spatial unstable regions. On the other hand, the repetition of each of these methods, especially when it is intended for a large area, is very costly and time-consuming. The existence of such constraints has always been one of the fundamental challenges faced by researchers in relation to precise measurements and spatial monitoring of land surface changes. Due to the fact that landslides directly affect the surface of the earth, the use of remote sensing techniques in instability studies of the slopes seems to be very suitable. Among the remote sensing techniques, radar interferometry (InSAR), capable of working in all weather conditions and the duration of night and day, is one of the most effective and efficient techniques for detecting and monitoring the steady change of the earth's surface. Of course, the lack of spatial and temporal correlations in available radar images limits the use of conventional radar interferometry to monitor the displacement of ground level. Persistent Scatter Interferometry (PSI) is the advanced InSAR technique which has significantly improved upon traditional InSAR methods by increasing the accuracy of results (millimeter scale precision). The main objective of this project was to detection and monitoring of Ahar Chai sub basin landslides based on PSI technique.
Matherials & Methods
This landslide with an area of about 42 hectares is located near the village of Dupiagh, located in Ahar city and 22 km on the Ahar-Varzaghan axis, in East Azarbaijan province, Iran. The geographical coordinates of the study area is N38 29´ and E46 49´.
For detection and monitoring of the landslide, the PSIn-SAR method was implemented on 22 ASAR images (with descending orbital modes) recorded between October, 20030502 and 20100709 by ENVISAT satellite in VV Polarization.
For detection and monitoring of Dupiagh landslide, the PSInSAR method was implemented on mentioned ASAR images. SARscape5.2 software on the platform of ENVI 5.3 was employed to process the radar images and to extract the persistent scatterers.
The PSInSAR processing technique was performed within five stages including: (1) selection of master image or connection graph selection. (2) Interferometry or interferometric workflow stage consisting of co-registration and differential interferogram generation parts. (3) First step inversion for selection of the candidate persistent scatterer points. (4) Inversion: second step including phase unwrapping and filter implementation stages. (5) Geocoding or conversion of the phase into displacement. Finally, The PSInSAR method results compared with dual-frequency -GPS measurement.
Discussion of Results & Conclusions
Based on the ASAR images processing by PSInSAR method, results showed that some parts of Dupiagh landslide are still active and displacement rate of the this landslide was obtained 12.4 mm/year duration of 2003 to 2010. While, the ground surface displacement velocity was estimated between 58 to -22.5 mm/year in the Ahar Chaiy sub basin duration the mentioned period.
The results of GPS measurement indicated that the Dupiagh landslide was inactive duration of observation baseline.
Differential RADAR Interferometry (DInSAR) method in detection and monitoring of landslides has been reported in numerous studies. Also, the study suggests that PSInSAR is a powerful technique to determine displacement and spatial pattern of landslides.