Morphology,grain size and environmental wind regine of granule ripples in the Sanlongsha area of the Kumtagh Desert
Granule ripple is a coarse-grained aeolian sand geomorphology composed of bimodal sediments,but the relationship between its development and wind regime,grain size and morphology is rarely reported.By means of field investigation,field observation and experimental analysis,the grain size and morphology of typi-cal granule ripples and the characteristics of wind regime in Sanlongsha area are studied.The results show that the length of granule ripples ridge in the study area ranges from 1.23 m to 24.05 m,with an average of 5.22 m.The average spacing between the ripples is 2.52 m,and the range is between 2.62 m and 4.73 m.The height of the granule ripples is between 0.07 m and 0.41 m,the average is-0.91 Φ,and the RI index is 17.61.The particle size distribution of the sediments is bimodal or trimodal.The average particle size of the surface(0-1 cm)and the sublayer(1-5 cm)is 0.64 Φ and 1.32 Φ.The average wind speed in the study area is 4.19 m·s-1,and the aver-age sand-driving wind speed is 8.65 m·s-1.The main wind season is in summer.The annual drift potential in the study area is 804.88 VU,and the seasonal wind direction variability is greater than 0.8,which belongs to low wind variability,and the drift potential is large in spring and summer,accounting for 67.1％of the annual total.The RDD is 200.2°,which is basically perpendicular to the movement direction of the granule ripples.
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