1-Introduction
Desert areas face many changes due to their sensitive ecosystems and morphology. Changes in desert areas are affected by various natural and human factors, including hydroclimatic factors, wind speed and direction in the region, destruction or creation of vegetation cover, etc. Among the forms of desert areas that face many changes and in many cases cause hazards and crises are sand dunes or sandbars. In fact, sandbars in desert areas consist of a set of sand dunes that have diverse morphology and active dynamics. In addition to the positive potential they have in the field of tourism development, etc., sandbars are also associated with many environmental consequences and problems. Given that most sandbars are dynamically active, the sand dunes in sandbars have a significant advance towards agricultural lands and infrastructure every year and can directly cause the destruction of these uses. Also, in many cases, sand dunes are considered dust centers and, depending on the speed and direction of the winds in the region, they can cause dust storms and thus create crises for different regions. Considering the importance of the issue and also because no comprehensive studies have been conducted regarding sand dunes located in the southern regions of the Alborz highlands and the Kavir plain, this research has examined the morphological and dynamic status of the sand dunes in this region.

2-Materials and methods
This research is based on remote sensing and statistical data, and descriptive-analytical methods have been used to analyze and interpret the information. In this research, various data, including statistical information related to wind speed and direction of 12 meteorological stations and satellite images (Google Earth and Landsat 8), have been used as the most important research data. Also, Google Earth software (to draw the exact area of sand dunes and monitor their movement), ArcGIS (to prepare the desired maps), and WRplot (to analyze the wind speed and direction of the region) have been the most important research tools. Considering the subject and objectives, this research has been carried out in several stages. In the first stage, using Google Earth images, the exact area of sand dunes of the Kavir plain and southern Alborz has been drawn, and then its morphometric status has been examined. In the second stage, according to the shape of the sand dunes, the sand dunes of the Kavir plain and southern Alborz are divided into different classes. In the third stage, using 203 sample points and Google Earth images, the amount of sand dune movement in the region during the years 2005 to 2020 was evaluated. In the fourth stage, based on the information of the studied meteorological stations, the wind speed and direction of the region were evaluated.

3-Discussion and Results
The results of this study have shown that a large part of the desert areas of the southern Alborz regions and the Kavir plain are covered by sand dunes, so that the total area of sand dunes in this region is about 13,081 square kilometers. Among the sand dunes of the southern Alborz regions and the Kavir plain, the Jen, Shotori, and Kashan-Ardestan sand dunes have the largest areas with an area of 4,744, 2,823, and 2,134 square kilometers, respectively. Given that the sand dunes of this region are very diverse in terms of wind speed and direction, as well as topographic conditions, they are also very diverse in terms of appearance. In this study, the sand dunes of the region have been divided into 10 classes. Based on the results obtained, the thin sand cover, complex transverse sand dunes, and complex sand dunes have the largest area with an area of 2944, 2876, and 2447 square kilometers, respectively. Also, based on the results obtained, about 78 percent of the sand dunes in the region are active, so that the displacement of the sand dunes of this region during the years 2005 to 2020 was between 5 and 65 meters, and in general, the highest displacement was related to the southern areas of Shotori erg. In this study, the wind speed and direction of the region and its relationship with the shape and movement of the sand dunes of the region were also evaluated. Based on the results, the highest wind speed was in the southern areas of Jen and Kashan ergs.

4-Conclusion
The results of this study have shown that there was no significant relationship between the morphological and dynamic state of the sand dunes in the region and the speed and direction of the winds in the region. According to the results, in some areas, such as the northern areas of Kashan erg, there was no correspondence between the wind speed and the amount of sand dune movement, the main reason for which was the morphological and vegetation status. Considering the above-mentioned cases, the morphological and dynamic state of the sand dunes in the studied area was affected by the wind speed and direction, vegetation, and the geomorphological status of the area. The overall results of this study have shown that the sand dunes in the region have a great diversity in terms of morphology, which can be used for various purposes, including tourism development. They are also dynamically active, and given that some of them, including the Kashan-Ardestan erg, are near populated areas, they can cause destruction of agricultural lands and other man-made uses, so it is necessary to take necessary measures, including stabilizing them using vegetation cover