Deserts and semi-arid regions are in the "Arid Lands", which include super-arid, arid, semi-arid, and semi-arid arid regions. Drylands cover about 45–47% of the global land area (Prăvălie, 2016; Koutroulis, 2019) and are home to about 3 billion people who live mainly in semi-arid and semi-humid regions (IPCC,2022). Drylands host unique, rich biodiversity (Maestre et al., 2015, Al-Hemoud et al ,2020, Norouzi, 2019) and provide important ecosystem services (Bidak et al., 2015; Liu et al., 2020).
The results of the sixth assessment report (IPCC,2022) indicated the destruction of pastures, soil erosion, reduction of production efficiency, an increase of runoff, and decrease in vegetation index have led to desertification. In the same report, climatic events such as (decreased rainfall, increased temperature, wildfires, floods, heavy rainfall, heat waves, and drought), and human activities such as (changes in land use, urban growth, overgrazing pastures, and destruction of forests) are effective in increasing desertification.
Climate change and human activities in recent years have led to an increase in the frequency and intensity of dust storms(Kok et al,2021, Wu,2021). Therefore, it has created important challenges in sustainable development and increased the level of environmental vulnerability. Soil erosion, land use change, dam construction, desertification, increase in temperature, increase in livestock grazing, and destruction of pastures, which are related to socio-economic effects, are effective in the process of increasing and intensity of dust (Engelstaedter et al, 2006, Gholami et al,2020 ,2020, and Emamian et al ,2021, Baltaci H,2021). The decrease in the level of underground water and the drying up of wetlands and reservoirs significantly affect desertification and dust in Iran (Alizadeh 2013). The findings indicated that dust increases with climatic drought, reduction of river hydrological flow, and reduction of vegetation (Hossein Hamzeh et al., 2021, Javan and Teimouri,2019).
Desertification leads to Changes in herbaceous cover, sand and dust storms, water scarcity, and human health. Dust emissions are highly sensitive to changing climate conditions but also to changing land use and management performance (Middleton, 2019). The findings indicated that land degradation, loss of vegetative cover, and drying of water bodies in semiarid and arid areas will contribute to sand and dust activity (Mirzabaev and Stringer ,2022). SDS continues a major worry for desert regions under conditions of climate change and desertification (Middleton, 2017).
In some locations, such as the USA, desert dust can be deposited downwind on snowpacks, hastening snowmelt and altering river hydrology (Painter et al., 2010). Deserts, playas, and salt marshes produced 75–90% of atmospheric dust in the early 21st century, and land use changes and degraded pastures caused by human activities accounted for the remainder (Ginoux et al., 2012; Stanelle et al., 2014).
Recent changes in dust emissions and their proportions vary geographically. In Iran, during the years 1951 to 2013, with the increase in temperature, dust events have increased (Alizadeh- Choobari and Najafi, 2018), the investigation of the performance of dust on the Saccharum officinarum product in the southwest of Iran showed that due to the dust, the photosynthesis process of the plant is disrupted and its efficiency is reduced by 30% (Arvin et al., 2013, - Bayat et al ,2016, Malaki et al ,2017), in the southwest of the United States of America, with the increase in drought (2000–2014), dust events have also increased (Hind et al. al., 2017). The decrease in soil moisture and the drying up of wetlands and reservoirs significantly led to increasing desertification and dust (Ravi et al ,2004, Mahmoodabadi and Rajabpour,(2017, Koohizadeh, et al, 2021). The increase in dusty days in the southwest of Iran led to a sharp decrease in the air quality index and an increase in respiratory diseases and a decrease in human health, the standard of living, air quality, and an increase in migration in Khuzestan province, Iran (Shahswani et al. 2013, Amarlui et al. 2013, Khavarian et al ,2019, Hejazi et al,2022).
The Study Area:
This area is located at the longitude of 29 ◦ 57’to 33 ◦ 4 ‘ of North latitude and 47 ◦ 38 ‘ to 50 ◦ 32’ of East longitude, it is located in the Southwest of Iran and the northwest of the Persian Gulf(Statistical yearbook of Iran,2020),(Fig. 1). It is in the southwest of Iran, bordering Iraq and the Persian Gulf. The Khuzestan province can be divided into two regions; the rolling hills and mountainous regions N
orth of the Ahvaz Ridge, and the plains and marshlands to its South. In the South part province, there is wind erosion(Ahvaz, Abadan, and Mahshahr), (Brown Color, Fig. 1)). These areas are the internal source of dust in Khuzestan province.
Data :
The South of Ahvaz ridge is the internal source. Therefore, our focus for station data analysis is on meteorological stations in this region. The analyzed data includes rainfall, air temperature, dust, and soil temperature in meteorological stations (1985–2019) (Fig. 2). In addition, Landsat 8 satellite images in the seasons (winter, spring, summer, and autumn) were used to investigate and change the environment in the dry year (2017) and wet year (2019). Using these images, changes in land surface temperature(LST), and normalized land cover index(NDVI) have been investigated. The study focuses on two years, a drought year (2017) and a wet year (2019), for evaluating environmental degradation. The data recorded in meteorological stations were daily, and these data were analyzed monthly and annually.