Study On Characteristics Of Natural Raindrop Outside And Inside Plantation In Yangling Shaanxi

Yangling located in southern of Loess Plateau, it is a potential hazard area of soil erosion.The data of natural rainfall observation was seldom, and the study on Water erosion process isnot enough. In this paper, the object of study is natural rainfall in Yangling. Experimentdesigned four different types of rainfall, Robinia pseudoacacia Linn,Populus tomentosaCarr,Acer truncatum Bunge and Outside the forest, and analyzed the natural rainfall theraindrops characteristics and difference inside and outside plantation. The main conclusionsare as follows.(1) The distribution of natural raindrop size outside the forest was coincidented withBest's function in Yangling.(2) The median raindrop diameter and the kinetic energy outside the forest wasdecided by rainfall intensity and Rainfall, and had the power function.(3) Rainfall erosivity-R is closely linked with rainfall in Yangling,so rainfall can beused to estimate the size of the rainfall erosivity。EI10and EI30are basic formula that is usedto created a simple model,when the rainfall is common rainfall,EI30is the best；when therainfall is short rainfall formation,EI10is the best.(4) The median raindrop diameter under the canopy of raindrops related small torainfall intensity。The median raindrop diameter under Robinia pseudoacacia Linn rangedfrom2mm to6mm；The median raindrop diameter under Populus tomentosa Carr rangedfrom1mm to4.5mm；The median raindrop diameter under Acer truncatum Bunge rangedfrom1mm to5mm. Canopy rainfall kinetic energy depends largely on the raindrop diameter,it is not the same as the rainfall outside forest。When rainfall intensity is less than0.1mm·minx^-1,canopy have increased the role of rainfall kinetic energy；When rainfallintensity is more than0.1mm·minx^-1,canopy rainfall kinetic energy tends to decrease。Therainfall kinetic energy under Robinia pseudoacacia Linn ranged from15J·mx^-2·mmx^-1to16J·mx^-2·mmx^-1；The rainfall kinetic energy under Populus tomentosa Carr ranged from8J·mx^-2·mmx^-1to16J·mx^-2·mmx^-1；The rainfall kinetic energy under Acer truncatum Bunge rangedfrom10J·mx^-2·mmx^-1to15J·mx^-2·mmx^-1.(5) When rainfall intensity is small and canopy density is big,The median raindrop diameter under the forest is biger the same as the rainfall kinetic energy,and vice versa.