نوع مقاله : مقاله علمی - پژوهشی
نویسندگان
1 دانشیار دانشگاه پیام نور
2 جغرافیا، دانشکده علوم اجتماعی، دانشگاه پیام نور، اصفهان، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Desertification after climate changes and deficiency of fresh water is the third important global challenge during
the 21st century. This phenomenon is the consequence of a series of processes in which climate change
and human activities are more important factors than others. Therefore, recognition and assessment of the desertification
trend are very important issues for better region management. Hence, the aim of this study is the
assessment of desertification changes in Qom province using Landsat satellite images, TM5 and LCDM8 sensors
in(1984-2013) with emphasis on the precipitation. Indicators used in this study are Normalized Difference Vegetation
Index (NDVI) and Soil Salinity Index (s1, s2, s3). According to Fuzzy ARTMAP method, the land use during
the period of (1984-2013) recognized and the land use changes were evaluated based on the Multilayer Perceptron
Neural Network (MLP) Model in software TERRSET. To study the effect of precipitation on desertification, the
monthly data of GPCC have been used and the spatial-temporal trend of annual precipitation was evaluated using
the Mann-Kendall nonparametric test at 0.95 level of significance. The results showed that the salinity and the
desert lands have been increased relative to the first year of study period from 3% to 18% and about 15% growth.
The vegetation has arrived from 7% to 2% that about was reduced 5%. The greatest increase of saline land is seen
in the western part of Qom, which replaces the vegetation. The increasing amount in saline and desert lands is
about 1751 km2. Study of land use changes illustrated that saline lands and city are growing whereas vegetation,
Sultan-Houz Lake, Salt Lake, and arid lands are reducing. The analysis of precipitation spatial-temporal trend
revealed a decreasing trend on annual time series at the 0.95 level of significance. Obtained results provide a basis
for better recognition and proper combating desertification in the studied region.
کلیدواژهها [English]