关键词: 古尔班通古特沙漠, 风沙活动, 线形工程, 风沙危害

Abstract: Gurbantonggut Desert, located in Junggar Basin in north Xinjiang, with an area of 48000 km², is the second largest desert in China. It is comprised mainly of fixed and sem-i fixed longitudinal dunes. In recent years, many linear engineering projects have been constructed across the longitudinal dunes. This has disturbed the sand surface and blown sand now threatens the projects. This paper has analyzed wind data and sand movement to investigate the patterns of blown sand motion on the dune surface and discussed its threat to linear engineering projects.
Affected by the west current and Mongolian high pressure, the preliminary wind directions are NE and NW, and their strong period is from April to July. The resultant wind-blown sand route in Cainan is N-S. From the bottom to the top of dune, there is a change of sand activity from weak to strong. In a 24 hour sampling period our research showed that the sand transport rate at the crest is 2000 times greater than that in the interdune. The pattern of blown sand motion on longitudinal dune surface is characterised by erosion on the windward slope and deposition on the leeward slope. Sand particles on the top of the longitudinal dune are transported alternately from side to side, while moving forward along the ridge from north to south. The base of the dune remains unchanged.
Without a protection system the linear engineering projects face the direct effect of sand erosion and deposition. This usually occurs when the cutting heads of the dunes move from north to south and bury the projects. Protection using only a straw barrier system (checker boards) on the disturbed face was largely ineffectual because sand moving along the top of the dune rapidly buried the protective system. Fill from the excavation of the longitudinal dune was placed on the interdune area, leading to the formation of a small but relatively steep sand slope. Although, the fill area was fixed with check boards the steepness of the man-made slope means that this surface is prone to erosion from the dominant northerly winds.
The key point of protection should be the cutting head of the longitudinal dune. On the one hand, the high barrier system should be set up on top of dune in order to decrease the wind velocity and block the blown-sand. On the other hand, straw-check board should cover a significant area along the active belt and decrease the sand source. In the interdune area a gently sloping face should be created on the sand fill. Revegetation should be implemented after establishing the mechanical protection system.

Key words: Gurbantonggut Desert, pattern of blown sand motion, linear engineering projects, wind sand disasters