Determination of key factors of soil loss equation of red-soil slop land in northern Jiangxi province

Abstract: A soil loss equation is an important technique for monitoring and preventing soil erosion. Based on field observation data from runoff plots, standards on erosive rainfall in red-soil slop land located in northern Jiangxi province were defined by using the method of 80% experience frequency. Results showed that the rainfall amount, average rainfall intensity, and break point intensity of 30 minutes of erosive rainfall standards were 10.0 mm, 1.3 mm/h, and 5.0 mm/h, respectively. The best result of individual rainfall erosion was calculated through the product of the total rainfall energy and the break point intensity of 30 minutes. The soil loss equation of the red-soil slop land in northern Jiangxi province was established based on building annual rainfall erosion regression models, selecting the topographic factor algorithm, measuring the value of the soil erodibility factor, and calculating the factor values of six biological measures and five engineering measures factors. The mean relative error (MRE), linear regression coefficient (R2), and the Nash-Suttclife efficiency coefficient (Ens), were used in the simulation results evaluation. Upon testing, when preventing annual average erosion intensity, the MRE, R2 and Ens were 5.48%, 0.99, and 0.99 for the simulation values of the soil loss equation and the observed values. When preventing inter-annual average erosion intensity, the R2 and Ens were 0.95 and 0.89. The results suggested that the equation can be used to predict annual average and inter-annual average soil erosion intensity precisely. However, its predicting accuracy is reduced while rainfall significantly deviates from multi-year mean level or gully erosion and other types occur on slope land. All of these can provide technological support for the monitoring and planning of water and soil conservation in the southern red-soil area.