摘要
选择河北昌黎黄金海岸状态自然、规模高大、形态典型的海岸横向沙脊,野外实地观测不同风速下海岸沙丘表面风沙流中不同粒径组沙粒垂向分布的变化。结果表明,随着风速的增大,海岸横向沙脊表面不同粒径组的沙粒在距地表60 cm高度内输沙量的垂向分布呈现出了不同的变化特点,其中粗沙的总输沙量减少,但中沙和细沙增加,在不同高度层内的变化亦不一致;相对输沙量基本呈现为下层减少、中层增加或基本持平、上层减少的变化特点,但各个变化层位的高度不一;垂向分布模式,粗沙转变为典型负幂函数分布,中沙由负幂函数转变为指数函数,细沙则为典型的指数函数布模式。究其原因,主要应与不同风速气流的携沙极限、随风速增大增加了沙粒的搬运高度以及不同粒径组沙粒的主导运动方式有关。
The change data of vertical distribution of different grain size sands at different wind velocity, including the data of structure of wind-sand flow and its grain size composition of sands at different heights on the crest of typical coastal transverse ridge at Changli Gold Coast in Hebei Province, which is one of the most typical coastal Aeolian distribution regions in China and famous for the natural and tall and typical coastal transverse ridges, was measured in the field and analyzed. The results showed, on the conditions of near total sand transport rates and the same surface material and environment, with the increasing of wind velocity, vertical distribution of different grain size sands in the wind-sand flow in 60cm height over the coastal dune had different change features. With the increasing of wind velocity, the total transport rate of coarse sands decreased, but medium sands and fine sands increased, and the changes at different height of sand transport rate were not the same. The change of ratio of sand transport rates of different height layer in total sand transport rates, with the increasing of wind velocity, normally presented as decreasing in low layer, increasing in middle layer and decreasing in high layer, but the heights of every layer for coarse sands and medium sands as well as fine sands were different. For the vertical distribution model of the sand transport rate in the wind-sand flow, coarse sands changed into typical power function with the increasing of wind velocity, medium sands changed form power function into exponential function, fine sands could be expressed by the typical exponential function. These changes had a close relationship with the limit of sand grain size of wind flow transporting with definite wind velocity, the change of sand carrying height with the wind velocity change and transporting ways of different grain size sands in the wind-sand flow.
出处
《中山大学学报（自然科学版）》
CAS
CSCD
北大核心
2008年第5期98-103,共6页
Acta Scientiarum Naturalium Universitatis Sunyatseni
基金
国家自然科学基金项目资助(40571019
10532030)
关键词
风速
海岸沙丘
粒径
垂向分布
wind velocity
coastal dune
grain size
vertical distribution
