干旱区生态环境知识资源中心

In arid and semi-arid regions, the dust storms are a common phenomenon. Kuwait is an arid country. Most of the lands in Kuwait are desert with low density of vegetation cover; therefore, these areas are exposed to dust most of the year. With the effect of wind particles move in three different modes of transport as creep, saltation, and suspension. The saltating particles on hitting the surface dislodge particles to air, they remain in air for longer period, and this process is called suspension. This commonly form thick sand cloud across the country during dust storm. The total numbers of dusty days in Kuwait are 255.4 days. It means that sandstorms and dust storms occur almost all the year. Most dominant plant species have the ability to trap sediments (sand and fallen dust) and form sandy mound around it called nabkha. There are three types of nabkhas based on their sizes: small, medium, and large nabkhas. The efficiency of trapping sediment depends on the height of canopy and size of bush of nabkhas. Different perennial plant species can form nabkhas such as Haloxylon salicornicum, Cyperus conglomerates, Rhanterium epapposum, Astragallus spinosus, Citrullus colocynthis, Halocnemum strobilaceu, Salicornia europaea, Tamarix aucheriana, Lycium shawii, and Nitraria retusa. Each plant must reach 10-15 cm in height before they can effectively trap sand. Once trapped in a nabkha, these cemented particles do not readily become wind re-entrained. Individual plant can form nabkha with unique sedimentological and morphological characteristics. The efficiency of the plant species in trapping sand was measured by estimating the volume of trapped sand for each plant. N. retusa, H. salicornicum, and L. shawii are the most efficient plant species in Kuwait in trapping mobile sand. These species trapped an average of 2, 1.25, and 1.2 m(3), respectively, of mobile sand and fallen dust. Most surface sediments consisted of coarse, medium, fine and very fine sand and few mud. Native plant species plays a major role in minimizing, controlling, and reducing fallen dust.