فرسايش بادي ، رخساره ها، و خسارت آن در حوزه دشت يزد - اردكان

Wind Erosion, Facies and Damages in Yazd - Ardakan Plain

Yazd- Ardakan plain is located in central Iran, between Yazd and Ardakan with an area of about 650,000 hectares. Mean annual rainfall is less than 65 mm.Rainfall distribution is uni-modal with more than 70%of it occuring in winter. Wild plant density varies from 25% to O. Artemisia sieberi is the prevalent plant species.A major part of Yazd -Ardakan plain is bare land. Topographic conditions, soil erodibility and wind storms have been formed to a big Erg with an area of about 28,560 ha. Several kinds of sand dunes such as:barkhan ,barkhanoid ,sif ,silk ( Linear dune ) and ghourd ( Star dune ) were diagnosed in this Erg. The highest sand dune is 19 m high and the longest is a bout 7 km wide. Many kinds of abrasion facies are formed in Yazd plain, from pediments (coarse grain plain) to piedmont or bajada (fine grain plain) such as Hamada (Desert pavement, Reg), parabolic shape (ventifact marking on the soil crust), Nebkha ,Rebdoh, Yardang (Kalut ), respectively. Although several parts of Yazd Erg and their origin areas have been fixed by different kinds of wind erosion control methods, wind storms still cause some damages to other parts of Yazd - Ardakan plain. According to the recent investigation more than 20,000-m3 dust with less than 100 micron diameter falls down annually in Yazd City with an area of 7000 ha. Horizontal visibility is reduced to less than 6m in stormy days in some parts of Yazd -Ardakan plain. This phenomenon causes car accidents on the main Yazd -Ardakan, road and can cancel airplane flights during the stormy days. At present, it is estimated that wind erosion causes more than 6.82 million $ damages to socio-economic resources in Yazd plain each year. Without a proper and prompt management, we may see more treats and hazards to human life in these areas.