| Sand trap is an important technical means for quantitative monitoring of wind-blown sand activities.At present,mechanical sand trap is still the main type of sand trap with wide application and high efficiency,but mechanical sand trap can not continuously and dynamically observe wind-blown sand flow.In this paper,A cyclone type continuous-weigh sand trap(CCST)is developed,which is applied to the field wind and sand observation experiments on sandy land and farmland soil in Bashang,Hebei Province.The performance of the CCST is verified by BSNE sand trap and new Flat Opening Collector(NFOC),comparisons with Wenglor laser particles counter.The results are as follows:(1)The structure of CCST includes bracket,collecting-sand modules,data logger and a solar panel powers.The sand trap can make gradient combination of several collecting-sand modules at different heights,collect sand samples at different heights at a single point,adjust the direction of the sand inlet according to the wind direction,and reduce the observation error.With high automation and high precision of sand collection data,it can realize real-time continuous monitoring of wind-sand flow.(2)The cumulative sediments weight of the CCST for 15,30 and 60 cm decreases exponentially with the increase of altitude.The relationship between the aeolian sediment flux and wind speed at 15 cm height satisfies the exponential relationship.Because of the vibration error caused by fluctuating wind,the relationship between sediment flux at 30 cm and 60 cm height and wind speed is poor.The aeolian sediment flux at altitudes of 0-60 cm is consistent with the observation results of NFOC,showing a significant linear correlation(R~2=0.7447).It shows that the CCST can capture the information of sediment transport well below the height of15 cm,but the correlation between wind speed and aeolian sediment flux becomes worse with the increase of the height of sediment collection.It shows that the CCST can realize continuous monitoring of wind and sediment activities at a certain height in the field.(3)The cumulative sediments weight of the CCST for 5 cm,15 cm and 40 cm heights also satisfies the law that the cumulative sediment concentration decreases exponentially with the increase of height.The relationship between the aeolian sediment flux and wind speed at 5 cm and 15 cm altitudes satisfies the exponential relationship.Because of the existence of vibration error,the exponential relationship between the aeolian sediment flux and wind speed at 40 cm altitudes is weak.The aeolian sediment flux measured by BSNE is linearly correlated with the wind speed(R~2=0.8912).The results show that the CCST can well observe the dynamic changes of wind-sand flow in farmland soil.(4)The aeolian sediment flux measured by CCST is compared with the number of sand particles measured by Wenglor laser particles counter.The number of sand particles passing through each minute measured by Wenglor laser particles counter has significant correlation with wind speed in three sample plots,and the correlation is the best in the beach sandy land with coarse grain size.The relationship between the number of sand particles per minute measured by Wenglor laser particles counter and the aeolian sediment flux measured by CCST on three sample plots was also analyzed,and the correlation between them was significant.In conclusion,the CCST can capture the transport information of wind erosion materials at a certain height well.The field application effect is good.It is suitable for automatic monitoring of high-precision wind erosion activities in the field.It has a wide application prospect.However,in the strong wind conditions,there are still inevitably problems of instrument jitter and increasing data errors,so the structure needs to be further improved.Wenglor laser particles counter is also a kind of instrument suitable for wind-sand observation in the field,but it needs to solve the problem of easy contamination of lenses. |
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