عنوان مقاله [English]
Background and objectives: In recent decades, Urmia Lake has been faced with a significant reduction in the water level.With the continuation of these conditions, the lake will be completely dry and an important environmental issue in the region. Human factors such as land use change are one of the most important factors in the formation and intensification of this crisis. On the other hand, for the optimal management of water and soil and sustainable production in the catchment area, it is necessary to know the exact changes in land use and agricultural land development. The main purpose of this research is to investigate the temporal changes of land use in a 26-year period in the Nazlou Chai sub basin, one of the important sub basins of Urmia Lake catchment area. For this purpose, satellite imagery, GIS tools and land-based data were used to detect and analyze the changes.
Materials and methods: In this study, Landsat satellite images were used in 1992, 2013 and 2018. The first year, before the beginning of the lake water level reduction, was selected in 1992. Considering that 2013 is the beginning of more serious activities for the restoration of Urmia Lake and the policy of banning agricultural development and land use change in this catchment area, this year was selected as the second year. The third year was also selected in 2018 (5 years after the more serious start of development inhibitory policies) to assess the latest state of the land use. Using the necessary pre-processing and classification with the maximum likelihood (supervised) method, land use maps were obtained in Envi version 5.3.
Results: Investigating land use maps shows that during the 21 years (from 1992 to 2013), rainfed 18049 ha, orchards 3997ha, irrigated agriculture 1559ha, stone 11048ha, and salt 639ha have increased. While, the rangeland has decreased by 38001 ha. Also, changes in land use over the past 5 years (from 2013 to 2018) has been faced with the highest increase in orchards (about 7143ha), then, rainfed (about 5444 ha). By contrast, there is a decrease in rangeland (about 2725ha), stone (about 4902ha) and irrigated land (about 5417 ha).
Conclusion: The results showed that a lot of land use changes in the sub basin have occurred during 26 years. In the last 5 years, despite increasing attention to preventing the development of agricultural lands, while continuing this incremental trend, land use change in orchards has had the highest change in the study area (about 50%). This significant increase in the development of orchards after 2013 indicates the need for revision of water and soil management in the basin and attention to effective factors such as integrated management of water and soil resources in the catchment areas and socio-economic issues.