海岸沙丘表面不同部位风沙流中不同粒径沙粒垂向分布的变化

河北昌黎黄金海岸典型沙丘的实地观测表明,风沙流中中沙与细沙输沙量的垂向分布在沙丘表面不同部位的变化并无本质性差别但有一定变化幅度的差异,如绝对输沙量均在迎风坡至丘顶增加、丘顶至背风坡坡脚减小,但中沙输沙量在迎风坡增加的幅度小于细沙、在背风坡减少的幅度大于细沙;相对输沙量在沙丘不同部位的变化趋向类似,但细沙的变化幅度要小于中沙;中沙的垂向分布模式均为幂函数,细沙则表现为指数分布(0~10cm高度内)和幂函数分布(10~30cm高度内)。

Change of Vertical Distribution of Different Sand Grain Sizes in Wind-sand Flow at Different Sites over Coastal Dune

Changli Gold Coast in Hebei Province is one of the most typical coastal aeolian dune distribution regions in China, one of dunes in this area was chosen to measure the change of vertical distribution of different sand grain sizes in wind-sand flow at the different sites over coastal dune. The field measurement results show that the change models of vertical distribution of medium sands and fine sands in wind-sand flow at the different sites over coastal dune have no essential difference, there is only some difference in the extent of change. All the aeolian sediment transport rate of medium sands and fine sands increase on windward slope and decrease on leeward slope, but the increase rate of eolian sediment transport rate of medium sands on windward slope is slower than fine sands and the decrease rate of Aeolian sediment transport rate of medium sands on leeward slope is faster than that of fine sands. The ratio of aeolian sediment transport rate of medium sands and fine sands at different heights in the wind-sand flow over coastal dune almost have the same change trend among different sites over dune, but the extent of change of medium sands is larger than the extent of fine sand change. At all the sites over coastal dune, the vertical distribution model of aeolian sediment transport rate of medium sands in wind-sand flow is power function, the vertical distribution model of fine sands could be expressed by an exponential function in 0-10 cm height and by the power function at the height of 10-30 cm.