气象因子对黑河中游荒漠-绿洲过渡带斑块植被区风沙活动的影响

Effect of Meteorological Factors on Sand Activities at Oasis-Desert Ecotone in the Middle Reaches of the Heihe River Basin of China

气候变化对荒漠-绿洲过渡带斑块植被区的风沙活动影响巨大,对该区植被的演化趋势有着重要作用。利用2012—2013年的气象资料,结合植被区255个样点的风蚀积沙量野外观测资料,分析了甘肃临泽县荒漠-绿洲过渡带气候变化特征及其对地表风沙活动的影响。结果表明:(1)2012年和2013年平均气温、积温(≥10℃)变化均呈单峰型,平均温度影响近地面空气对流运动,积温(≥10℃)影响植被的生长,两者间接地影响风沙运动;(2)2012年和2013年降水差异显著,空气相对湿度呈双谷型变化,降水和空气湿度对地表下垫面的影响十分复杂,对风沙活动的影响较为复杂;(3)2012年和2013年起沙风频率变化呈三峰型,全年输沙势分别为412.21VU、375.41VU,分别属于高风能环境、中风能环境,方向变率指数0.31~0.78,以中变率为主;(4)2012年和2013年输沙率同输沙势或合成输沙势均呈非线性相关且强弱不同,2012年在小变率条件下输沙率受输沙势的影响较大,受合成输沙势的影响较小;2013年在中变率条件下输沙率受合成输沙势的影响较小,受输沙势的影响较大。

Climate has a huge impact on sand activities and vegetation evolution trend at oasis-desert ecotone.Based on the meteorological data in 2012 and 2013 from Linze inland river basin research station,and the sand deposition data from the 255 sampling points in the oasis-desert ecotone,the characteristics of climate change and its effect on the surface sand activities in the desert-oasis ecotone were analyzed.The results show that:(1)The changes of the average monthly temperature and the monthly accumulated temperature(≥10 ℃)are the type of the uni-modal in 2012 and 2013.The former influences the sediment transport over surface layer,while the latter influences the plant growth and plant coverage.(2)The precipitation is different and the air relative humidity changes with the double-dip variation by month in 2012 and2013.Rainfall and the air relative humidity have the complicated influence on the earth surface and sand activities.(3)The sand-drift wind frequency changes with the three peaks.The annual drift potential in 2012 and 2013 are 412.21 VU and 375.41 VU,belonging to high and medium wind energy environment,respectively.The index of direction variable ratio is priority to the medium ratio in 0.30-0.78,and both of them belong to the medium variable ratio in 2012 and 2013.(4)The relationships are non-linear between the rate of synthetic sediment transport and the drift potential or the resultant drift potential in 2012 and 2013.Under the condition of small variability sediment rate in 2012,the rate of synthetic sediment transport is affected significantly by drift potential,and the influence of the resultant drift potential is not significant.Under the condition of medium variability sediment rate in 2013,the rate of synthetic sediment transport is not affected significantly by drift potential,and the influence of the resultant drift potential is significant.