青海共和盆地威连滩沙地冲沟风水交互作用研究

选择青海共和盆地威连滩沙地冲沟为研究区,通过野外调查,沉积物样品采集和分析,结合1982年航片和2006年快鸟影像数据,分析研究区地质历史时期风水交互作用的环境变化和沙地冲沟风水交互侵蚀的现代特征。结果表明:全新世初期,研究区由水成沉积环境逐渐过渡到风成沉积环境,并有小的沉积旋回,到了全新世中期,气候变得较温润,风沙活动减弱,风成沙逐渐生草成土,但弱砂质古土壤层较薄,从全新世晚期至今,风沙活动有所增强;冲沟形成后,沙地冲沟发生着风蚀水蚀交互作用。起伏的沟岸和弯曲的谷底发生风积,为流水侵蚀增加了沙物质。风沙流对冲沟的形成有再塑造作用。同时冲沟侵蚀也影响着风沙活动,每年冲沟侵蚀约达8.3×104 t泥沙,是沙丘不断增长的一个重要物源。冲沟的狭长地形,其"狭管效应"加大了风蚀作用,增强了风沙灾害天气。

Study on Aeolian-fluvial Interactions of Gully Erosion in Sandy Land in Weiliantan,Gonghe Basin,Qinghai Province

The authors chose gully erosion in sandy land in Weiliantan,Gonghe basin,Qinghai province as the studied object.By field investigation,collection of sediment samples and analysis,with the assistant of aerial photo in 1982 and the remotely-sensed imagery Quick Bird data in 2006,the authors analyzed the environmental change of aeolian-fluvial interaction in geologic time and the modern characteristics of aeolian-fluvial interaction of gully erosion in sandy land.The results show that sedimentary environment has been in the transition from water erosion to wind erosion,and had a little sedimentary cycle since early Holocene.Climate became relatively warm and moist in middle Holocene,thus wind-sand activity weakened and sand dunes experienced soil formation.Again,aeolian activities have enhanced since late Holocene.Gully in sandy land has been eroded by water and wind since gully formation.Wind accumulation(windblown deposit) on the undulate gully bank and at the winding bottom of gully supplies water erosion with sandy deposit.Sand flow has a function of gully reshaping on the sandy land;in turn,gully erosion also has an effect on aeolian activities.Annual sediment from gully erosion is about 8.3×104 t,so it can be considered as an important source of dune growth.In addition,long and narrow gully has funneling effect,and this fact can induce more serious aeolian erosion and sand storm disaster.