Document Type : Original Article

Subjects

• Geomorphology, natural geography

1. Introduction

Dust storms are meteorological phenomena triggered by turbulent winds that remove loose sand from exposed dry topsoil in arid and semi-arid areas, causing the movement of sand dunes or airborne dust. Dust storms have a linear correlation with climate variables, and today, with the acceptance of climate change, its frequency and intensity are expected to increase in countries located in the arid and semi-arid belt. The issue of atmospheric dust has garnered growing attention in recent years and has resulted in significant damage and casualties worldwide annually. The phenomenon of dust and the movement of quicksand are considered important processes of land destruction and serious challenges in the world. Climatic factors also play a significant role in these phenomena. Therefore, investigating and recognizing these factors and their impact on the mobility of quicksand and the intensification of dust phenomena is an undeniable necessity to prevent the escalation of environmental crises in the future. The recent droughts have exacerbated the drying of Lake Urmia, leading to a significant expansion of its dry bed. This situation has increased the possibility of wind erosion and dust storms in the Lake Urmia basin. In this study, we aimed to investigate the impact of drought frequency and severity on dusty days in the East Azerbaijan province over the past 30 years (1990-2020). Conducting this research is essential for evaluating the temporal-spatial distribution of wind erosion, identifying areas at risk of desertification, and developing control strategies for these areas.

2. Materials and methods

The studied area is East Azerbaijan province, located northwest of Iran. Based on the archival information of East Azarbaijan Province Meteorological Department, from the total of 19 active synoptic stations in this province, 10 meteorological synoptic stations that have long-term statistics in the last 30 years (1990-2020) were selected for use in this research First, using the correlation equation, the missing value of the number of days with dust of the synoptic stations was completed in the last 30 years. The homogeneity of the meteorological data series was assessed using the non-parametric run test, which involved selecting the median of the data in the SPSS software environment. The homogeneity of the data was assessed using the P-value. A P-value less than the significance level of 0.05 indicates rejection of the null hypothesis or rejection of the randomness of the data. Then, the trend of this data was checked using the Mann-Kendall test. The frequency and severity of droughts were calculated using the SPEI method in the R program. Then, the impact of droughts on the occurrence of dust was evaluated through the Spearman correlation test.

3. Discussion and results

The missing data of the number of days with dust in the selected stations was completed based on the Spearman correlation test between the data series of these stations and linear regression calculation for the recent 30-year period (1999-2020). The run test results showed that the null hypothesis was confirmed at a significance level of 0.05 in four stations as Jolfa, Maragheh, Sarab, and Kalibar. In the rest of the stations, the number of days with dust data is not homogeneous. A trend in the data series at a significant level of 0.05 has been confirmed, and the Sen’s slope values also indicate that this trend is increasing. The results of the SPEI index show that drought periods are expanding, especially in the second half of the selected period in the region. On the other hand, there was a significant correlation at the 0.01 level between the number of days with dust and the SPEI-6 drought index.

4. Conclusion

The playa of Urmia Lake is the main focus of local dust generation, and this fact is confirmed based on the correlation between the dust and the SPEI index, as well as the observation of suspended particles with lake origin in the air of the stations near this lake. However, demonstrating the impact of prolonged droughts and the enlargement of the dry bed of Lake Urmia on local dust requires ongoing and precise monitoring of the quantitative and qualitative attributes of wind deposits at all meteorological stations in this area.

5. Aknowledgmant & Funding

This work was supported by the Research Institute of Forests and Rangelands (RIFR) of IRAN.

The authors are thankful to all interview participants for supporting this research.

6. Conflict of Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.