Characteristics of Wind Erosion and Deposition in Oasis-desert Ecotone in Southern Margin of Tarim Basin,China

The oasis-desert ecotone is a fragile ecological zone that is affected both by oasis and desert conditions. To understand the impact of the differences in wind power, and the influence of wind erosion and deposition on the ecotone, meteorological data and contemporaneous wind erosion and deposition data were collected on the southern margin of Tarim Basin with serious sand-blown hazards. The wind velocity, average wind velocity, sand drift potential(DP), resultant sand drift potential(RDP), and sand transportation rate decrease significantly and successively across four landscape types with increasing vegetation coverage(VC). Flat surfaces and areas of shifting sandy ground experience intense wind erosion with fast movement of mobile sand dunes; semi-fixed sand areas experience extensive wind deposition but only slight wind erosion; and fixed sand areas experience only slight wind erosion and deposition. Volume of wind erosion on bare newly reclaimed farmland is up to 6.96 times that of bare shifting sandy ground. Wind erosion volume per unit area and VC follow an exponential function relationship in natural conditions, while wind deposition volume per unit area does not conform to any functions which has close relationship with vary topography and arrangement patterns of vegetation besides for VC. The results indicate that the volume of wind erosion has a close correlation with VC, and different types and distribution patterns of topography and vegetation also profoundly influence the wind deposition volume in the field, and underground water tables in different landscape types control the plant community distribution.

Characteristics of Meteorological Factors over Different Landscape Types During Dust Storm Events in Cele,Xinjiang,China

Landscape characteristics influence meteorological factors, thus affect the occurrence and nature of dust storm events. The present study investigates the spatiotemporal characteristics of six meteorological factors （wind velocity, wind direction, air temperature, relative humidity （RH）, photo synthetically active radiation （PAR）, and solar radiation） over different landscape types （shifting-sand frontier, semi-fixed sandy land, fixed sandy land, and the inner region of an oasis） before and after dust storms during four typical dust storm events in an oasis-desert ecotone in Cele, Xinjiang, China. The results show that the average wind velocity decreased significantly from the shifting-sand frontier to the inner oasis, which was mainly attributable to the vegetation coverage. Before the dust storm events, there were obvious differences in air temperature and RH either in the horizontal or vertical direction over the different landscape types. However, these factors were very similar during and following the dust storm events. PAR and solar radiation were significantly reduced during the dust storm events and the subsequent sand-blowing and floating-dust conditions. This effect was much stronger than during similar weather conditions without dust storm events such as sand-blowing and overcast and/or rainy days. Additionally, the variation in the meteorological factors among the different landscapes was also affected by the prevailing wind direction during the dust storm events. However, the landscape type slightly changed the prevailing wind direction, with the greatest dispersion distribution of wind direction in the inner oasis. The findings of this study are helpful for understanding the function of landscape types in the occurrence of dust storms, as well as for providing a theoretical basis for prevention of dust storms.