JiangXi Rainfall Erosivlty Research Under Global Climate Change Background

Jiangxi province is one of those provinces in the South China which have the heaviestsoil erosion.Some researches have shown that global climate changes have a great chanceto increase the extreme weather. It has positive significance on the prediction of soilerosion and on the development of soil and water conservation to study the temporal andspatial distribution and variation tendency of rainfall erosivity and accurately evaluate thepotential effect of rainfall on soil erosion.Based on the precipitation data of37stations inJiangXi province during the period of1959-2011.A simple algorithm of rainfall erosivitythat is suitable for Jiangxi area is choosed by contrast and used to calculate rainfallerosivity. It analyzes the temporal and spatial changing rules of precipitation and rainfallerosivity in Jiangxi province by use of the ordinary Kriging. It meanwhile uses the CMIP5global climate models to simulate precipitation。Using the linear regression predictionmethod analyzes the change trend of Rainfall Erosivity in Jiangxi. the conclusions are asfollowing:（1） In the spatial distribution, the overall distribution of precipitation is that the easternand southeast regions is generally high, the northwest and southwest regions is generallylow, the central region is moderate.High values appear in Shangrao area, low areas appearin Jiujiang、Taihe. In the decadal spatial distribution, rainfall is dynamic; each era showsthe variation of oen high and the one low.53years，the precipitation is dynamicallychanging， the high and low value district of every period is changing too. In seasonaldistribution，the precipitation changes between the six stations and whole province arebasically the same. The precipitation proportion in a year presents a trend ofspring>summer>winter>autumn. From the average level of37stations, the annual rainfallis mainly concentrated in the February to August, the total proportion of73%, the largest ofwhich in June, accounting for17%of full scale.（2）Four kinds of monthly rainfall erosivity models that ever used before in red soilarea are choosed. The rainfall erosivity model based on monthly rainfall which is foundedby Huangyanhe is more suitable for the calculation of the rainfall erosivity in Jiangxiprovince through analysis.（3）Through correlation analysis，the result shows that the power function model fittingthe relationship of precipitation and rainfall erosion effect is the best result.It uses themodel-y=axbto regression analysis and return authentication in the whole area of jiangxiprovince. Finnally， there gets a calculation formula about R-value fitting annual rainfallerosion in Jiangxi province as following:R=0.0476P^1.5998Among， R is annual Rainfall erosion (MJ mm hm^-2 h^-1 a^-1); P is annual precipitation （mm）.（4） In the spatial distribution， the two obviously low value area of rainfall erosion inJiangxi province are jiujiang and taihe; While the obviously high value area is wuyuan; atthe same time， the rainfall erosion in other areas is moderate. On the time distribution，53years， the change rule of R-value is undulate， while the overall trend is flat. In theyears spatial distribution， the distribution of rainfall erosion is the dynamic change，eachera shows the variation of oen high and the one low. On Seasonal distribution，rainfallerosivity focused on spring and summer. From the average level of37stations, the annualrainfall erosivity mainly in March-August, accounting for80%of full scale, the largest ofwhich in June, accounting for21%. For the cities and counties which is in the high values,the relevant departments should strengthen supervision and management and soilconservation control work.（5） Compared with the past50years, the rate-k of rainfall and rainfall erosivity issmall, compared to the past50years, the positive and negative trends were not significant.The trend of the rainfall and the rainfall erosivity is upward over most parts of JiangxiProvince in the past, while for the next20years, rainfall and rainfall erosivity shown adownward trend in most parts of Jiangxi Province, only the northern and northeasternregions of Jiangxi, including Ruichang, Hukou, Jiujiang, Jingdezhen, Boyang, Leping,Wuyuan, Shangrao, Kwong Fung, Yushan and other regions which rainfal and rainfallerosivity in the past and future are showing an upward trend.