| Slope farmland is the main source of soil and water losses,accounting for more than 70%of dry land area in red soil region of southern China area.It is vulnerable to serious soil erosion due to the dual influences of climate change and anthropogenic activities.Thus it has become the focus and hotspot in the field of soil erosion.But there are still many deficiencies in the study of soil erosion dynamics monitoring,formation mechanism and water conservation tillage regulation technology.Accordingly,the research took Jiangxi soil and water conservation ecological science and Technology Park as the study area.Based on the artificial rainfall simulation(indoor and outdoor)and long-term fixed monitoring data of 15 field runoff plots,the applicability of close-range photogrammetry technology in dynamic monitoring of slope soil erosion in north of Jiangxi province in China,the characteristics and laws of soil erosion and rainwater resource formation on sloping farmland in north of Jiangxi province in China were systemically analyzed through using laser,close-range photogrammetry and modern mathematical statistics analysis technology.And the effects of different soil and water conservation tillage measures to control soil erosion and rain water resources on slope land and technology integration were also studied The main research results are as follows:(1)The specific rainfall characteristics of two artificial precipitation devices were compared and analyzed,and the three-dimensional dynamic information of soil erosion was extracted under different rainfall intensity and water impact test by using close range photogrammetry.The dynamic monitoring and detail analysis of soil erosion on slope space point could be realized,and the relationship model between soil erosion thickness and soil erosion was established.Through the field natural rainfall and artificial simulative washing test,compared with the traditional soil erosion monitoring method,the monitoring accuracy could reach more than 75%,the highest accuracy could reach 94.33%.According to the relevant national and industry standards,the three-dimensional dynamic monitoring technology system of sloping farmland soil erosion based on close-range photogrammetry technology was established,which could provide effective technical support for dynamic monitoring of soil erosion on sloping farmland and similar objects on northern slope of Jiangxi province,as well as play a supporting role for the analysis of effectiveness of soil and water conservation control.(2)The soil erosion level of the original bared slope of sloping farmland in north of Jiangxi province was always higher than the strong level.Its runoff yield and sediment yield were mainly concentrated in 4-9 months,accounting for more than 96%of the total annual output.The rainstorm over rainfall type on the contribution of rate of runoff and sediment yield was up to 80%.There was significant correlation of rainfall kinetic energy(E),rainfall(P)and rainfall erosivity(EI30)with runoff yield and sediment yield,and rainfall kinetic energy(E)has the best correlation.The driving models of runoff and sediment of the different rainfall characteristic factors were built,the driving models were mainly presented as a linear,two time curve and power function relationship.The coefficient of rainfall characteristic factors and runoff yield models were generally higher than that of sediment yield models.At the same time,based on stepwise multiple regression method,the multiple linear driving model of runoff yield and sediment yield of bare slope land on sloping land was set up.(3)From the angles of different time scales and rain types,the effects of different soil and water conservation tillage measures on soil erosion control on slope were systematically analyzed.The effects of prevention and control soil erosion of longitudinal ridge were not good enough,and the runoff and sediment yield in the specific month and storm rain type were larger than that of the naked control plot.This fully showed that the longitudinal ridge tillage,as a popular tillage measure,would suffer the serious soil erosion in case of heavy rainfall under the circumstance of artificial farming activities,especially the land preparation,harvest and fallow period.At this stage,more attention should be paid to the implementation of soil erosion control technology.The remaining soil and water conservation tillage measures,except that the sediment reduction rate of cross slope ridge below the heavy rain type was the highest,the effects of the runoff reduction and sediment reduction of composite measures 2 were most prominent,and all of them were more than 87%.There was a significant difference between the longitudinal ridge tillage and other measures in reducing runoff and sediment yield(p<0.05).On the whole,the effect of the ranoff reduction and sediment reduction of the compound measures 2,which focus on cultivation,water storage and diversion,was the most prominent.Through setting up the driving models of runoff and sediment yield of different soil and water conservation tillage measures,it was found that the implementation of the measures can effectively change the driving mechanism of different rainfall characteristics factors on slope runoff and sediment yield,so as to control soil and water loss of slope.Through the simulation study of applying PAM soil and water conservation tillage measures to control the slope soil erosion,it is found that the runoff of sloping fields was improved obviously,and the runoff promotion rate and the time of steady flow were different after spraying PAM on 4 typical kinds of slopes in northern Jiangxi province.The sediment yield of each slope decreased significantly,and the rate of sediment reduction was the most significant in the Quaternary red soil,but the rate of sediment reduction was slightly different.The effects of different proportions of PAM on controlling soil erosion on different sloping land slopes are also different.The results can provide reference for chemical regulation of soil erosion on slope land in northern Jiangxi province and other regions.(4)The runoff,infiltration characteristics and the relationship between crop water storage and rainwater supply and demand were analyzed in the longitudinal ridge cropping system of rape-peanut rotation in northern Jiangxi province.The runoff of slope was mainly concentrated in the period of 4-9 months,accounting for more than 82%of the total annual output.The rainfall kinetic energy(E)was the main factor of rainfall characteristic driving factors affecting the runoff yield.The coefficient of runoff in the whole growth period of rape was mainly between 1.8%?7.6%,and the coefficient of runoff in the whole growth period of peanut was mainly between 7.5%?27.8%.And the runoff coefficient of the flowering and pod period was larger,the runoff coefficient of single rainfall could be as high as 55%.During the fallow period of two crops,the loss of rainfall and flood resources was more serious.Thus reasonable biological interception should be taken to improve the interception of rainfall on the slope surface,and so as to improve the soil water productivity of sloping farmland.The effect of rainfall on the soil moisture content of 0?30cm soil layer was remarkable,and the above slope position was the best.In the seedling stage,rape required the largest amount of water,accounting for more than 50%of the whole growth cycle,and then the flowering period was about 20%of the whole growth cycle.And there was a lack of effective rainfall only at seedling stage.In the whole growth cycle of peanut,the water was deficient only in the stage of mature.(5)Based on the existing soil and water conservation tillage measures,the technical system of rainfall interception and infiltration technology,slope water system diversion and storage infiltration technology system were concluded,and the water and soil conservation tillage and flood resources optimization and utilization technology system of slope farmland under the mode of rape-peanut rotation in northern Jiangxi province with rainwater interception and infiltration and storage irrigation were developed.And the effects were analyzed from the aspects of best soil water content,soil water storage capacity,increasing increment,prevention and control of soil erosion,and the individual technology all had good results.The integrated technology could increase the soil water content of 0?30 cm by 15.49%,and improve the soil water storage capacity by 27.29 mm.The soil water content was close to the optimum soil water content at the stages of rapeseed seedling,mature and peanut seedling respectively.The average annual reduction rate and sediment reduction rate of the integrated technology system were 94.32%and 98.69%,respectively,which were the highest compared with the individual technology.The yield of the integrated technology could reach up to 3617kg/hm2,and the output value could reach up to 3.26 million yuan/hm2.It was the highest compared with the individual technology.Through the effective integration and reasonable allocation of the individual technology,the rainwater resources of the slope are effectively collected,meanwhile the water saving and efficiency increasing were prominent. |
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