This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination. IEEE GEOSCIENCE AND REMOTE SENSING LETTERS 1 Desiccating Lake Urmia: A New Dust Source of Regional Importance Mahdi Boroughani, Hossein Hashemi , Seyyed Hasan Hosseini, Sima Pourhashemi, and Ronny Berndtsson Abstract— Lake Urmia (LU) in northwestern Iran has largely shrunk over the last two decades. The emerged bare, salty soil could turn into a threatening new dust source for the densely populated region around it. To quantify LU as a dust source, we examined the satellite data for 2000–2017 using an extended dust source enhancement technique. Our results indicate that the number of dust events increased with a significant inverse corre- lation to the lake area. We investigated over 2000 satellite images encompassing LU to find the sources of the dust. We present new satellite images showing the first strong evidence that the dried area of the lake has become an active dust source of regional importance. The critical dust sources were found close to LU. If the negative trend of LU surface area remains unchanged, more intensive and frequent dust events are expected, which will negatively impact a larger area surrounding LU. Index Terms— Dust source, Lake Urmia (LU), Moderate Resolution Imaging Spectroradiometer (MODIS), remote sensing (RS). I. I NTRODUCTION L AKE Urmia (LU) in northwestern Iran is the second largest lake in the Middle East and one of the largest permanent hypersaline lakes worldwide [1]. The endorheic lake, with an approximate drainage area of 52 000 km 2 , supplies an important agricultural region with a population of about seven million people. Due to human activities in the region (e.g., improper water management) as a primary factor [2], accompanied with frequent meteorological droughts in the basin, the lake water level and surface area have Manuscript received May 23, 2019; revised September 18, 2019; accepted October 12, 2019. This work was supported in part by the MECW Program at the Center for Middle Eastern Studies, Lund University, Sweden. (Corresponding author: Hossein Hashemi.) M. Boroughani is with the Research Center for Geosciences and Social Studies, Hakim Sabzevari University, Sabzevar, Iran (e-mail: m.boroughani@hsu.ac.ir). H. Hashemi and R. Berndtsson are with the Department of Water Resources Engineering, Lund University, Lund, Sweden, and also with the Cen- ter for Middle Eastern Studies, Lund University, Lund, Sweden (e-mail: hossein.hashemi@tvrl.lth.se; ronny.berndtsson@tvrl.lth.se). S. H. Hosseini is with the Department of Water Engineering, Faculty of Agriculture, Tabriz University, Tabriz, Iran, with the Department of Water Resources Engineering, Lund University, Lund, Sweden, and also with the Center for Middle Eastern Studies, Lund University, Lund, Sweden (e-mail: seyyed_hasan.hosseini@cme.lu.se. S. Pourhashemi is with the Department of Geomorphology and Climatology, Hakim Sabzevari University, Sabzevar, Iran (e-mail: s_pourhashemi@ yahoo.com). Color versions of one or more of the figures in this letter are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/LGRS.2019.2949132 Fig. 1. Geographic location of LU. The circular area colored in transparent red indicates the buffered zone with a radius of 500 km (LU environmental disaster from the aerosol pollution perspective) from the edge of the Lake. dramatically declined over the last two decades [3]–[5]. This has caused an environmental disaster by increased salinity in both groundwater and lake water that have had adverse effects on ecosystems, agriculture, livelihoods, and health [6]–[8]. An outcome like that observed for the Aral Sea is most likely to occur for this lake. The Aral Sea dried up over the past few decades and negatively affected the surrounding region with windblown salt storms [4], [7], [9], [10]. Moreover, the population around LU is much larger than that of the Aral Sea, and thus, a larger population is at risk. Satellite imaging has revealed that the LU surface area declined from 6100 km 2 in 1995 to 2366 km 2 in August 2011. This corresponds to approximately 39% decrease during the period [11], [12]. The lake contains an estimated 8 billion tons of salt [13]. In the case of complete desiccation, releasing large amounts of salt by windborne transport could lead to an ecological, agricultural, and social catastrophe, not only for Iran, but also affecting neighboring countries such as Turkey, Iraq, Armenia, and Azerbaijan [11], [12], [14]. An examination of the spatiotemporal nature of aerosol around LU is very important for the people living in the lake basin and ∼80 million people living within a radius of 500 km [15] (see Fig. 1). A recent study investigated the LU environmental disaster from the aerosol pollution perspective using the satellite product aerosol optical depth (AOD) that is based on observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA Terra satellite [15]. Mardi et al. [15] found that the AOD increased between 2001 and 2015 in northwestern Iran and suggested that the 1545-598X © 2019 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. 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