| There is very serious soil loss in China,and then the use of land resources is greatly affected.The raindrop splash and concentrated runoff caused by rainfall is the main driving force of water erosion.Therefore,the study of erosional dynamics is the basis and premise for the accurate prediction of soil loss.The eroding force of all the erosive rainfall is calculated with the rainfall erosivity index in a certain period.As it is difficult to obtain rainfall energy data of the single rainfall process,the rainfall erosivity model is usually fitted to estimate the rainfall erosivity.The conventional rainfall data mainly comes from rainfall stations and other regular rainfall statistics,such as rainfall,monthly rainfall,and annual rainfall.With the development of new advanced monitoring technologies,this makes the computation of rainfall kinetic energy and rainfall erosivity possible,and brings new opportunities and challenges for the theoretical research of soil erosion dynamics.In this study,three rainfall instruments,which was Instruments included automatic meteorological station,automatic rain gauge,and 2D-Video-Distrometer,were installed on the top of building of the soil and water conservation department of Yangtze River Scientific Research Institute.The influences of rainfall data monitored by three kinds of instruments on rainfall,rainfall kinetic energy and rainfall erosivity were compared and analyzed.Eight formulas for calculating rainfall erosivity were used to compare.The main conclusions of this paper are as follows:(1)Combined with the rainfall values in rain station of the Hankou marshland during the 2016 and 2017,the accuracy in monitoring rainfall with three kinds of instrument is analyzed and compared.It shows that the accuracy of automatic rain gauge in monitoring rainfall is highest.The result of 2D-Video-Distrometer is in great deviation.It need further proof to show it can monitor rainfall Accurately or not.(2)The rainfall kinetic energy Ev can be directly calculated by using the diameter and velocity of raindrops with a new monitoring instrument called 2D-Video-Distrometer.The deviation between Ev and Er is in small deviation in 2014,and in the same way during 2016 and 2017.Er is calculated by Formula of rainfall kinetic energy used in RUSLE.It shows that the instrument may leak rain or rainfall.The rainfall kinetic energy Ev calculated directly by raindrop size and velocity can reflect the real rusults of 2D-Video-Distrometer,and as well as the rainfall erosivity calculated by Ev.(3)8 simple formulas for rainfall erosivity are selected.the results of EI10,EI60,PI10,andPI30 are all in great deviation with EI30 in Seven simple formulas for rainfall erosivity.The results of formula provided by YinShuiQina and WangWanZhong(1995)are both in small deviation with EI30 under the condition of automatic rain gauge.Only the result of formula provided by YinShuiQin is in small deviation with EI30 under the condition of 2D-Video-Distrometer.(4)The relationship between rainfall kinetic energy and rainfall has been analyzed under the condition of automatic rain gauge and 2D-Video-Distrometer.There is no obvious linear relationship between them,It is defective that the rainfall erosivity is calculated with rainfall instead of the rainfall kinetic energy.(5)Comparing with the relationship between the 2D-Video-Distrometer and automatic rain gauge in rainfall,modifier formula can be established to revise and check the rainfall kinetic energy Ev and rainfall erosivity in the condition of 2D-Video-Distrometer.In this paper,the modification of the rainfall kinetic energy is ideal,the modification of the rainfall erosion force need to be improved,and the further study is required for the final modification formula. |
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