Monitoring land use and cover changes in Qom province over 33 years using maximum likelihood and fuzzy methods

Inappropriate land use triggers and accelerates desertification process in arid and semi arid regions. The aim of this study was to evaluate the desertification impacts in Qom province through land cover/ land use changes in 33 years using Land sat 1976 TM, 1992 and 2009. Population data, livestock numbers and SPI indices were also compared during this period. First, geometric, radiometric and topographic preprocessing techniques were applied to the images and land use/cover maps were extracted using supervised classification (Maximum likelihood) and fuzzy method. The maps accuracies were assessed through overall accuracy and Kappa statistics. According to the results, the maps produced by Fuzzy methods had more accuracy than the Maximum likelihood method. The results also indicated that the size of rangelands decreased from 784281.to 662910 hectares and 34112 hectares of lands were transformed into salty areas during this period. The results showed that the size of urban and industrial areas and agricultural lands in the province were increased to 2864 and 131308 hectares, respectively. The Namak Lake was also completely dried in 2009. The results revealed that dam constructions, pumping underground water, continuous droughts and increasing livestock numbers were among the reasons of accelerating the desertification trend in Qom province especially in the eastern part; hence both management and environmental variables were responsible for these changes. Holistic and adaptive management approaches in natural resources management, and especially in water resource management can restore the province into the past conditions.