Cause of wind-blown sand disaster in Shiquanhe Basin and its control

Cold and arid climate,strong wind,and plenty of erodible material account for serious windblown sand disaster in the Shiquanhe Basin,northwest of Qinghai-Tibet Plateau.Gravel sand-barrier and tree shelterbelt serve as the main measures to control windblown sand,with artificial grasslands and irrigation systems also contributing.Based on wind tunnel experiments of the gravel sand-barrier and tree shelterbelt,and field measure for sand flux on a Gobi Desert surface,the barriers were installed with 1.2-m-tall and at an azimuth of 351.1°,forming an angle of 77° with respect to the prevailing wind direction in the basin.The spacing of the barriers equals to 12 times of its height.Tree shelterbelts are arranged parallel to the gravel sand barriers and separated by 43.2m,with local Salix hangongensis the main species.The permeability of the shelterbelts is designed to be between 0.5 and 0.8.The multiple rows of rationally schemed gravel barriers and tree shelterbelts can reduce wind speed below the threshold value required to initiate sand movement.Artificial grasslands were established between the gravel sand barriers and tree shelterbelts.