Sand transport of the main passages of the Alax Plateau, China
,2, Lianyou Liu1
,2, Guoming Zhang1, Jie Lei1, Haiming Wen1, Bo Liang1, Jiadong Dai1, Mengdi Zhao1
1MOE, Key Laboratory of Environmental Change and Natural Disaster, Ministry of Education, Beijing Normal University, Beijing, China, 2State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, China
The Alxa Plateau in the north China is characterized by frequent sand dust storm activity, desertification, various blown sand hazards and extensive sand dunes. Three of China's major sand desertsthe Badain Jaran, Tengger and Ulan Buh, are distributed in this region. Four sand transport passages stretch out from the Badain Jaran desert, connecting it with the Ulan Buh desert (termed ‘Badain Jaran and Ulan Buh desert sand transport passage’, BJD-UBD), the Tengger desert (‘the Badain Jaran and Tengger desert sand transport passage’, BJD-TD), the Minqin oasis (‘Badain Jaran desert and Minqin oasis sand transport passage’, BJD-MO), and the Zhangye oasis (‘Badain Jaran desert and Zhangye oasis sand transport passage’, BJD-ZO), respectively. Previous researches focused on each desert or oasis within the local region, separately, but little attention was paid to the sand transfer between two deserts, or between a desert and an oasis along the sand passages. In this study, we focused on the sand transport passages between two deserts, and between a desert and an oasis. By using remote sensing image analysis and field investigation, sand dune migration and wind regime of the sand transport passages between two deserts, and between a desert and an oasis were measured, the amount of sand transport in these sand transport passages were studied. The results showed that sand-transporting winds (≥6.0 m s–1) occurred mostly in spring and winter, and accounted for 16.4% of the total of the year in the BJD-TD. The prevailing wind directions were NW, WNW and NNW, and were occupied 61.9% of the total frequency of sand-transporting winds. The frequencies of winds decreased with increasing wind speed, and strong wind frequencies (≥17.2 m s–1) were 5.3% of the sand-transporting winds. In comparison to adjacent areas, the average wind speed and drift potential in the BJD-TD was several times higher, indicating an obvious effect of narrowing. Sand transport in the spring and winter accounted for 99.8% of the annual total while that in the prevailing wind directions accounted for 77.3% of the annual total. The sand transport flux in the BJD-TD, BJD-UBD, BJD-MO and BJD-ZO were 372.6 t m-1, 412.8 t m-1, 164.4 t m-1 and 21.6 t m-1, respectively, while the corresponding annual total amount of sand transport were 5.0×106 t, 2.8×106 t, 4.0×106 t and 1.1×105 t. The amount of sand transported by a single sand-transporting event varied greatly, up to five orders of magnitude.