Investigating the consequences of the desiccation of lakes in the Middle East and Central Asia for regional dust activity

Abstract

<p>Over the past several decades, new sources of dust aerosol have appeared in the Middle East and Central Asia due to the desiccation of lakes in the region. It is known that recently dry lakebeds can be efficient dust sources, due to the availability of readily erodible alluvial sediments. Such lake source regions include: Lake Urmia in western Iran; the Sistan Basin in the border area between Afghanistan, Iran, and Pakistan; and most notably, the Aral Sea on the border between Uzbekistan and Kazakhstan. A particularly large area (over 50,000 km<sup>2</sup>) of the former lakebed of the Aral Sea has become exposed to aeolian wind erosion, leaving Central Asia susceptible to dust storms originating from the young ‘Aral Kum’ (Aral Desert).</p><p>In this work we update the dust transport model COSMO-MUSCAT in order to simulate dust emissions from these relatively new dust sources. Making use of the Global Surface Water dataset (produced by the Copernicus Programme) in order to define the surface water coverage, we make estimates of dust emissions under three scenarios: 1) the ‘Past’, representative of water coverage in the 1980s; 2) the ‘Present’, representative of water coverage in the 2010s; and 3) the ‘Dry’ scenario, a worst-case future scenario in which currently drying lake regions are assumed to dry out completely under the pressure of climate change and water overuse. These scenarios are applied to the ‘Dustbelt’ modelling domain, covering North Africa, the Middle East and the Arabian Peninsula, and Central Asia as far east as western China.</p>