Abstract: Controlled by the landscape pattern of oasis and desert,the processes of wind-blown sand in the oasis-desert transitional zone have direct impact on the stability of oasis. In this paper,a typical oasis-desert transitional zone in Dunhuang Oasis at the east of Kumtagh Desert between Xinjiang and Gansu Province,China was selected the our studying site. With the methods of setting section from desert to oasis,fixed point observation in the field and mathematical statistics,the sand-laden wind,drift potential and drag velocity were calculated based on the meteorological data of the sites in the desert,oasis and desert-oasis transitional zone. This paper probes into the local wind regimes,wind speed profile,aeolian environments and drift potentials along the desert-oasis transitional zone under typical weather conditions. Results show that the frequency of sand-laden wind decreases obviously from desert to oasis,especially in the condition of sandstorm weather. The frequency of sand-laden wind is 96 in the desert,58 in the desert-oasis transitional zone and 7 in the oasis,respectively. Due to the impacts of the desert-oasis transitional zone,the dominant direction of wind also deviates from desert to oasis. Wind speed decreases from 8.59 m·s^-1 in the site of desert to 4.28 m·s^-1 in the site of oasis in sandstorm weather,which indicates an obvious defensive effect of oasis. In addition,drag velocity is 0.51 m·s^-1 in the desert,0.27 m·s^-1 in the desert-oasis transitional zone and 0.14 m·s^-1 in the oasis. Wind speeds on different heights have good correlation under the same underlying surface. The relationship of wind speeds on different heights decreases from desert to oasis. In the field observation periods,the site of desert has 196.81 VU of drift potential,which indicates high wind energy and strong aeolian sand activities. While in the sites of desert-oasis transitional zone and oasis, drift potential is 68.45 VU and 9.35 VU,both lower than that in desert. The result of this paper is beneficial to solve the sand hazards and ensure ecological safety of oasis. Moreover,it will provide scientific evidence for establishing the oasis-protection system in arid region which is both significant in theory and in practice.

Key words: weather condition, desert-oasis transitional zone, sand-laden wind, drag velocity, drift potentials