Geomorphological and spatial analysis of dust sources in Ilam Province, Iran

Abstract

Dust storms, which have become an environmental crisis in the Middle East in recent years, are associated with increased sources of sediment production. There are several reasons for the emergence of these sources, with the interplay between geomorphological processes and the production of landforms, which are susceptible to dust emission under certain conditions, being considered as its main reason. In this research, the most important dust production regions in Ilam province, located in the west of Iran, have been identified and their geomorphological characteristics have been analyzed in order to manage the environment. First, using MODIS images, applying the thermal-infrared dust index (TDI) and the HYSPLIT model during 21 dusty days from 2008 to 2013, the dust source areas were identified. Subsequently, a geomorphic map was produced and overlaid on the dust source map to determine the distribution and frequency of dust source points in each geomorphic class. Finally, field observations were conducted to analyze the geomorphological characteristics of the most important dust emission areas. The results revealed heterogeneity in the spatial distribution of dust sources in the area (235 points) concentrating in the regions of Mehran, Dehloran and Abu Ghovair where poor rangelands and agricultural lands predominate and abundant supplies of alluvial sediments exist. Indeed, dust mostly originates from landforms such as alluvial fans and floodplains whose dust-sized particles are renewed by seasonal floods annually. Thus, the availability of fine particles (clay and silt) in various geomorphic units plays a significant role in determining the dust emission capacity.