عنوان مقاله [English]
The importance of studies of sand dunes is due to their effects on water and soil resources, plant life and animals, and facilities and ways of communication. Due to the fact that the studied sandstone hills in this study are located adjacent to residential areas and agricultural lands, slightest changes in their nature and dynamics can have minor or major effects of relatively Sustain the local communities in these areas. The issues caused by storms, such as the outbreak of diseases, are due to the transmission of pathogens, transport disturbances, damages to residential areas and the destruction of livestock, including these effects. By considering the significant damage brought about by the movement and development of sand dunes, and the extensive application of remote sensing in the process of making these changes, the main objectives of this study are to investigate the changes of sand dunes in the studied area, to predict land use variations by 2031, and to predict changes in the area of sand dunes until 2048.
In this study, sandstone changes obtained from Landsat satellite data (TM5-ETM + -OLI), developed from the USGS website, have been used. In this research, the geometric correction of these images has been discarded due to the fact that the images on the United States Geological Survey refer to less than 12 meters of ground. the images were taken using the FLAASH atmospheric correction. For images categorization, after selecting suitable bands, educational samples were taken and then the image classification was obtained. After classification, grading accuracy was evaluated. Finally, the trend analysis was carried out using a cross-sectional model and a change modifier and prediction of changes through the Markov chain. Landsat images of TM5, ETM + and OLI were used to study the morphological changes in sand dunes in a 15-year period (2001-2016). The topographic map and data related to Google Earth have been used to assess the classification accuracy. ArcGIS, ENVI, EDRISI and ERDAS software are also used for data interpretation, processing and analysis.
Discussion and results
The trend of changes in the use of sand dunes during the period from 2001 to 2008 shows a decreasing trend. The results derived through reviewing the trend of changes in the second time period (2008-2016) show that the area of 10511.91 ha in 2008 was 1865.43 ha in dry and sandy areas and 68.31 hectares in the lands where the crop has become. An important point is that during this time period, the area of sand dunes has not been built into lands, because sand dunes can be dangerous for human settlements. Also, during this time period, the area of poor pasture land, dry land and saline lands and agricultural lands that are equivalent to 0.09, 87.66 and 2.34 hectares, are used for sand dunes it has become. The results of predicting land use changes for the next 15 years based on past changes indicate that the decline in sand dunes will continue in upcoming years so that 2468.79 hectares in the area of Bayer and Dandies, 365.22 hectares will be converted into agricultural lands and 900 hectares of land will be built.
the results show that the area of sand dunes has decreased from 2001 to 2016, with an area of 12715.20 hectares in 2001 to 8668.26 hectares in 2016. The main reason for this change can be the conversion of sand dunes to land use and insecticide land at a rate of 3621.42 hectares and agricultural use of 5422.5 hectare. According to the field observations in the area and the survey of satellite images, The main reason for the decline in the sand dunes has been desertification plans implemented in the past decades, as well as the natural growth of Haloxylon on sand dunes and surrounding areas, and have had positive effects on biological desertification initiatives in sand hills stabilization. The other results of this study are prediction of the area of sand dunes by 2048, which predicted the results showed that the area of sand dunes from 8668.26 hectares in 2016 will receive to 4041.36 hectares in 2048.