The Application of USEPA Model for Identification of Dust Sources in the Delazan District, Semnan County

Wind erosion and dust generation is a great challenge worldwide, especially in Iran. Identification of the dust source is the first step in mitigating this occurrence. There are various approaches to detect wind erosion and dust sources including remote sensing, physical and chemical analyses, experimental models. The purpose of this study was to use the US Environmental Protection Agency (USEPA) model to identify sources of dust in the Semnan Municipality. Samples were collected randomly from 50 study points in the Municipality of Semnan (2018), and physical and chemical experiments were performed on the samples. Climate indicators, namely: rainfall, evapotranspiration and wind speed, temperature, and relative humidity for a period of 9 years were also been collected from the Meteorological Organization of Iran. The dust emission rates of Q, Q30, and Q50 were measured separately using climatic parameters and physical characteristics of the soils in different models. Geostatistic and interpolation techniques, including RBF and IDW, were also used to plot the map of climatic parameters, texture, and dust emission rates. According to the statistical tests, only the values of silt, Q30 and Q50 were normal; therefore, an interpolation of these indicators was performed using the geostatistical methods. The critical and supercritical points of sources of dust were then determined after the maps were combined. The findings indicated that the study area was super-critical in drought (19.02), rainfall (177.96 mm), and region topography (plain) indicators, and in a critical condition for soil texture with an average of more than 50 percent sand and less than 30 percent silt. The dust emission rate (Q) ranged from 9-55 kg/ha.y pointed into the warning condition for, the regional average of dusty days (2 days/y). However, the days with a wind speed of 1.98 m/s were considered as a normal condition. In a nutshell, the results indicated that the study area was not a dust source, despite the critical and supercritical conditions for some of the indicators.