The Gobi deserts are important landscapes and major sandstorm source areas in arid northwestern China.Unsaturated sand flow and decreasing sand supply capacity is well known as the basic characteristics of gobi surfac...The Gobi deserts are important landscapes and major sandstorm source areas in arid northwestern China.Unsaturated sand flow and decreasing sand supply capacity is well known as the basic characteristics of gobi surface,but relatively little attention has been paid to the fetch effect of sand transport which is closely related to sand supply and indicative of wind erosion process in gobi.Using a field experiment,we investigated the spatial and temporal variations on a manually disturbed gobi surface downwind a sand-blocking belt and a sand-fixing belt by measuring the sand transport rate and the height profile of flux density at different fetch lengths during a sequence of wind erosion events.Results showed that the sand supply capacity determined the critical fetch length(Lc)for the sand transport rate so that the fetch effect varied with wind erosion proceeding due to depletion of erodible material.The height profile of flux density above the surface followed two distributions:an exponential decrease with increasing height,which commonly occurred above the newly treated gobi surface during the early wind erosion events;or a Lorentzian distribution with a peak flux at a certain height,which often happened in the later wind erosion events.The varying fetch effect,decreasing sand transport rates,and the nonerodible area expanded downwind are an epitome of the gobi development and expansion process from the perspective of wind erosion.展开更多
The wind fetch effect is important to wind erosion and aeolian transport and controls aeolian flux.It is useful to study the wind fetch effect in determining the aeolian transport mechanism and improving our knowledge...The wind fetch effect is important to wind erosion and aeolian transport and controls aeolian flux.It is useful to study the wind fetch effect in determining the aeolian transport mechanism and improving our knowledge of aeolian physics and wind erosion.In this paper,multichannel samplers measure aeolian transport at different heights above an artificial Gobi surface in the southeastern region of the Tengger Desert.The results show that aeolian transport flux can be expressed as an exponential function of height.Wind fetch obviously affects aeolian flux and aeolian transport.The coefficients and relative decay rate of aeolian flux decrease and then increase with increasing wind fetch distance.Aeolian transport depends on the height and fetch distance;aeolian transport increases and then decreases with increasing fetch distance,reaching a maximum at a fetch distance of about 34 m at the very near surface.The fetch distance of maximum aeolian transport tends to increase with height.展开更多
基金supported by the National Natural Science Foundation of China(No.41630747).
文摘The Gobi deserts are important landscapes and major sandstorm source areas in arid northwestern China.Unsaturated sand flow and decreasing sand supply capacity is well known as the basic characteristics of gobi surface,but relatively little attention has been paid to the fetch effect of sand transport which is closely related to sand supply and indicative of wind erosion process in gobi.Using a field experiment,we investigated the spatial and temporal variations on a manually disturbed gobi surface downwind a sand-blocking belt and a sand-fixing belt by measuring the sand transport rate and the height profile of flux density at different fetch lengths during a sequence of wind erosion events.Results showed that the sand supply capacity determined the critical fetch length(Lc)for the sand transport rate so that the fetch effect varied with wind erosion proceeding due to depletion of erodible material.The height profile of flux density above the surface followed two distributions:an exponential decrease with increasing height,which commonly occurred above the newly treated gobi surface during the early wind erosion events;or a Lorentzian distribution with a peak flux at a certain height,which often happened in the later wind erosion events.The varying fetch effect,decreasing sand transport rates,and the nonerodible area expanded downwind are an epitome of the gobi development and expansion process from the perspective of wind erosion.
基金supported by the National Natural Science Foundation of China (Grant Nos.41101007,41130533 and 41171010)
文摘The wind fetch effect is important to wind erosion and aeolian transport and controls aeolian flux.It is useful to study the wind fetch effect in determining the aeolian transport mechanism and improving our knowledge of aeolian physics and wind erosion.In this paper,multichannel samplers measure aeolian transport at different heights above an artificial Gobi surface in the southeastern region of the Tengger Desert.The results show that aeolian transport flux can be expressed as an exponential function of height.Wind fetch obviously affects aeolian flux and aeolian transport.The coefficients and relative decay rate of aeolian flux decrease and then increase with increasing wind fetch distance.Aeolian transport depends on the height and fetch distance;aeolian transport increases and then decreases with increasing fetch distance,reaching a maximum at a fetch distance of about 34 m at the very near surface.The fetch distance of maximum aeolian transport tends to increase with height.
