Effects of wetlands and wind velocity on dust propagation in arid areas: a critical case study in south-east of Iran

The most challenging issue of the Sistan region in Southeastern Iran, at least in the recent decades, has been dust propagation. The two main factors responsible for sand and dust storms, i.e., wind and land erosion, are extremely high in this region. The closest part of Hamoun wetland to Zabol, named Saberi, has been assumed as the primary source of Aeolian dust propagation in this study area. To examine the influence of the conditions of Saberi on dust storms, 113 satellite images of water coverage in this wetland in Iran were used, and the meteorological data for 2009–2018 were analyzed. The outcomes indicated no correlation between dust propagation and water coverage in the Iranian part of the Saberi wetland during the mentioned period. The correlation between windy days with a speed of more than 17 m/s and dusty days with visibility of lower than 2000 m was 0.73 (p < 0.01). The wind is a significant driving force of dust emission, but its direct effect was not constant during the study period. To investigate its impact, in the first step, the probability of dust emission was estimated for each wind velocity level using metrological data from 2003 to 2018. Afterward, the expected dusty days were determined for each year correspondingly. The index of wind impact, which is the proportion of expected to observed dusty days, was calculated for each year continuously. The index showed major variations between 0.5 and 2.7 due to the soil surface conditions. However, its value has been less than one in recent years, indicating specifically fewer windy days in the study area compared with previous years.