Investigation of the role of bed dried Gavkhooni wetland on the production of the internal dust using remote sensing and duststorms (Case study: Isfahan province)

Wetlands in the central Iran lakes are considered as part of desert ecosystems and their destruction leads to adverse consequences. In central part of Iran, climatic and human factors have created significant differences between dry and wet surfaces of Gavkhooni wetland in recent decades, leading to produce more dust in central part of Iran. The aim of this research was to assess the impact of dried bed of Gavkhooni wetland on the production of the internal dust in Isfahan province by using remote sensing and storm roses in the period of 22 years (1991- 1992 to 2011-2012). For this propose, the landsat imagery and anemometer data were used. After geometric and radiometric corrections, Normalized Difference Water Index (NDWI) was calculated and the dry and wet surfaces were separated. To determine wind erosion threshold velocity, undisturbed soil samples were transferred to the wind erosion meter. Then, the number of dusty days in the synoptic station of Isfahan was calculated based on the wind speed greater than wind threshold speed. Relationship between the number of dusty days and dried bed of wetland was evaluated with correlation analysis. Finally, to determine the dusty wind direction from the side of Gavkhuni wetland to Isfahan station, annual and seasonal wind roses and storm roses were plotted and evaluated. The results of this study based on the artificial neural network model showed that the most important factors influencing the bed of the Gavkhuni wetland were input flow rate, evaporation, drop in groundwater level, temperature, and rainfall, respectively. The results of the correlation analysis showed that there was a significant inverse relationship between the number of dusty days and dried bed of wetland in the seasons of autumn, spring, summer and annual scale in Isfahan station. Also, results of storm roses showed that dusty winds did not blow from wetland toward this station.