Comparing Various Techniques for Land Use-Cover Change Detection Using RS and GIS
Islamic Azad University, IRAN, ISLAMIC REPUBLIC OF
Timely and accurate change detection of earth surface features is extremely important for understanding relationships and interaction between human and natural phenomena in order to promote better decision making. Remote sensing data are primary sources extensively used for change detection in recent decades. In this study, images of landsat(TM) 1988 and landsat (ETM+) 2001 were analyzed using five change detection techniques in 80470 hectares in the region of Daresher,Ilam province. Change detection techniques considered were image differencing, image ratioing, NDVI differencing, change vector analysis (CVA) and postclassification comparison. In this study, from statistical method for determining the threshold level was used which from the change threshold was achieved. 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 was determined. Based on ground data and field visit and Google Earth, accuracy assessment of change detection techiques was carried out using overall accuracy and Kappa coefficient. According to the results,NDVI differecing with overall accuracy of 98.5 and Kappa coefficient of 97% showed the highest accuracy among applied change detetion techniques and on the contrary ,band ratioing with overall accuracy 72.5 and Kappa coefficient of 50% had lowest accuracy in land use/land cover change in study area.