风矢量对坡面降雨动能分布的影响

The effects of the wind vector on the distribution of raindrop kinetic energy over sloping field

风矢量的存在既改变了雨滴的下降速度 ,也改变了雨滴溅击地面的角度 ,对坡面雨滴溅蚀的影响很大。只有垂直于坡面的雨滴速度分量所决定的降雨动能才是坡面溅蚀的初始动力。故将静风条件下的雨滴最终速度和风矢量分解 ,得到垂直于坡面的雨滴合速度。根据雨滴速度的分布律 ,导出了雨滴动能的分布函数和分布密度 ,并通过积分求得不同风速条件下雨滴动能均值随坡向坡度的分布规律。

The kinetic energy of raindrop plays an important role in surface erosion processes. Wind affects not only the raindrop terminal velocity, but also the directional tilt of the raindrops, by which the angle of raindrop impacting on the soil surface will be determined. Thus it shows great influence on splash erosion on sloping field. The part of raindrop kinetic energy vertical to sloping field will be regarded as a kind of prime mover for splash erosion. Based on the distribution of raindrop terminal velocity, the raindrop kinetic energy distribution function and its density function were developed. As a consequence, the distribution of average raindrop kinetic energy over sloping field was obtained through calculus which varied with wind velocity, slope gradient and slope aspect as well as raindrop density.