Comparative characteristic of aeolian loessial soils samples,whose sections are from North China (Beijing)and pre-Caucasia(Bujennovck).As far as we know,there are many questions can be researched in the area of loess....Comparative characteristic of aeolian loessial soils samples,whose sections are from North China (Beijing)and pre-Caucasia(Bujennovck).As far as we know,there are many questions can be researched in the area of loess.For the sake of solving engineering and ecogeological problems,we have to begin with knowing loess’ composition,structure, physical,physicochemical,physicomechanical properties and first of all—the property of sedimenttation.展开更多
1. General Situation of Soil Erosion The loessial hilly area of southern Ningxia, Situated at the south of Ningxia Hui Au-tonomous Region, middle-upper reaches of the Yellow River, part of Chinese Loess Pla-teau, cove...1. General Situation of Soil Erosion The loessial hilly area of southern Ningxia, Situated at the south of Ningxia Hui Au-tonomous Region, middle-upper reaches of the Yellow River, part of Chinese Loess Pla-teau, covers an area of 1500 square kilometers with an annual mean temperature of 5-8℃,a precipitation of 300-500mm of which 70% taking place concentratively during the peri-od between June and September in form of rainstorm, The annual evaporation展开更多
Understanding the relationship between hillslope soil loss with ephemeral gully and rainfall regime is important for soil loss prediction and erosion control. Based on 12-year field observation data, this paper quanti...Understanding the relationship between hillslope soil loss with ephemeral gully and rainfall regime is important for soil loss prediction and erosion control. Based on 12-year field observation data, this paper quantified the rainfall regime impacts on soil loss at loessial hillslope with ephemeral gully. According to three rainfall parameters including precipitation(P), rainfall duration(t), and maximum 30-minute rainfall intensity(I_(30)), 115 rainfall events were classified by using K-mean clustering method and Discriminant Analysis. The results showed that 115 rainfall events could be divided into three rainfall regimes. Rainfall Regime 1(RR1) had large I_(30) values with low precipitation and short duration, while the three rainfall parameters of Rainfall Regime 3(RR3) were inversely different compared with those of RR1; for Rainfall Regime 2(RR2), the precipitation, duration and I_(30) values were all between those of RR1 and RR3. Compared with RR2 and RR3, RR1 was the dominant rainfall regime for causing soil loss at the loessial hillslope with ephemeral gully, especially for causing extreme soil loss events. PI30(Product of P and I_(30)) was selected as the key index of rainfall characteristics to fit soil loss equations. Two sets oflinear regression equations between soil loss and PI_(30) with and without rainfall regime classification were fitted. Compared with the equation without rainfall regime classification, the cross validation results of the equations with rainfall regime classification was satisfactory. These results indicated that rainfall regime classification could not only depict rainfall characteristics precisely, but also improve soil loss equation prediction accuracy at loessial hillslope with ephemeral gully.展开更多
文摘Comparative characteristic of aeolian loessial soils samples,whose sections are from North China (Beijing)and pre-Caucasia(Bujennovck).As far as we know,there are many questions can be researched in the area of loess.For the sake of solving engineering and ecogeological problems,we have to begin with knowing loess’ composition,structure, physical,physicochemical,physicomechanical properties and first of all—the property of sedimenttation.
文摘1. General Situation of Soil Erosion The loessial hilly area of southern Ningxia, Situated at the south of Ningxia Hui Au-tonomous Region, middle-upper reaches of the Yellow River, part of Chinese Loess Pla-teau, covers an area of 1500 square kilometers with an annual mean temperature of 5-8℃,a precipitation of 300-500mm of which 70% taking place concentratively during the peri-od between June and September in form of rainstorm, The annual evaporation
基金supported by the National Natural Science Foundation of China(Grant No.41271299)by the Opening Fund of MWR Laboratory of Soil and Water Loss Process and Control in the Loess Plateau of China(Grant NO.2017001)
文摘Understanding the relationship between hillslope soil loss with ephemeral gully and rainfall regime is important for soil loss prediction and erosion control. Based on 12-year field observation data, this paper quantified the rainfall regime impacts on soil loss at loessial hillslope with ephemeral gully. According to three rainfall parameters including precipitation(P), rainfall duration(t), and maximum 30-minute rainfall intensity(I_(30)), 115 rainfall events were classified by using K-mean clustering method and Discriminant Analysis. The results showed that 115 rainfall events could be divided into three rainfall regimes. Rainfall Regime 1(RR1) had large I_(30) values with low precipitation and short duration, while the three rainfall parameters of Rainfall Regime 3(RR3) were inversely different compared with those of RR1; for Rainfall Regime 2(RR2), the precipitation, duration and I_(30) values were all between those of RR1 and RR3. Compared with RR2 and RR3, RR1 was the dominant rainfall regime for causing soil loss at the loessial hillslope with ephemeral gully, especially for causing extreme soil loss events. PI30(Product of P and I_(30)) was selected as the key index of rainfall characteristics to fit soil loss equations. Two sets oflinear regression equations between soil loss and PI_(30) with and without rainfall regime classification were fitted. Compared with the equation without rainfall regime classification, the cross validation results of the equations with rainfall regime classification was satisfactory. These results indicated that rainfall regime classification could not only depict rainfall characteristics precisely, but also improve soil loss equation prediction accuracy at loessial hillslope with ephemeral gully.
