The characteristics of the snow-cover and snowmelt water storage in Gurbantunggut Desert.

Based on the field experiment and observation in the southern margin of the Gurbantunggut Desert,the characteristics of the snow distribution and snowmelt water storage in the sand soil,the efficiency of the snowfall water translated to soil water are analyzed and calculated.The main results including:(1) the snow in Gurbantonggut Desert belongs to "Dry-cold type" snow with low density.Based on snow depth,snow density and snow water equivalent,3 different periods of snow season are divided.There are snow accumulation period,snow maintenance period and snow melt period.The average snow density is changed between 0.14 to 0.27 g/cm3 in different period,and the average snow depth is 20 cm to 30 cm in general.(2) Spatial differences are existed for the snow-cover distribution.There are no regularity for the snow depths variation in the top,hill and foot of sand dunes.Compared with the topography,the main desert shrub—Haloxylon ammodendron with sparseness distribution has more evident effect for the snow-cover depth variation.(3) Vertical infiltration is the mainly hydrological process of the snowmelt water.There are no surface water delay and confluence process in the desert regions.The depth of wetted soil of the snowmelt water is about 40 cm to 80 cm.the wetted layer in top is deeper than flat land between sand dunes.(4) there is high water transfer and storage efficiency for the snowfall.78.8% to 92.0% of the snowfall water is transferred to the soil water.It is considered that the cold climate,sand dune topography,limited snowfall,low soil water content before the snowmelt and the high infiltration capacity are the main reason for the vertical infiltration and the high water transferred efficiency of the snowmelt water.