Soil erosion on highway side-slope has been recognized as a cause of environmental damage and a potential threat to road embankments in the high-altitude permafrost regions.To assess the risk to roads and to protect t...Soil erosion on highway side-slope has been recognized as a cause of environmental damage and a potential threat to road embankments in the high-altitude permafrost regions.To assess the risk to roads and to protect them effectively,it is crucial to clarify the mechanisms governing roadside erosion.However,the cold climate and extremely vulnerable environment under permafrost conditions may result in a unique process of roadside erosion,which differs from the results of current studies conducted at lower altitudes.In this study,a field survey was conducted to investigate side-slope rill erosion along the permafrost section of a highway on the Qinghai‒Tibet Plateau of China.Variations in erosion rates have been revealed,and intense erosion risks(with an average erosion rate of 13.05 kg/m^(2)/a)have been identified on the northern side of the Tanggula Mountains.In the case of individual rills,the detailed rill morphology data indicate that the rill heads are generally close to the slope top and that erosion predominantly occurs in the upper parts of highway slopes,as they are affected by road surface runoff.In the road segment scale,the Pearson correlation and principal component analysis results revealed that the protective effect of vegetation,which was influenced by precipitation,was greater than the erosive effect of precipitation on roadside erosion.A random forest model was then adopted to quantify the importance of influencing factors,and the slope gradient was identified as the most significant factor,with a value of 0.474.Accordingly,the integrated slope and slope length index(L0.5S2)proved to be a reliable predictor,and a comprehensive model was built for highway side-slope rill erosion prediction(model efficiency=0.802).These results could be helpful for highway side-slope conservation and ecological risk prediction in alpine permafrost areas.展开更多
The slope length factor is one of the parameters of the Universal Soil Loss Equation(USLE)and the Revised Universal Soil Loss Equation(RUSLE)and is sometimes calculated based on a digital elevation model(DEM).The meth...The slope length factor is one of the parameters of the Universal Soil Loss Equation(USLE)and the Revised Universal Soil Loss Equation(RUSLE)and is sometimes calculated based on a digital elevation model(DEM).The methods for calculating the slope length factor are important because the values obtained may depend on the methods used for calculation.The purpose of this study was to compare the difference in spatial distribution of the slope length factor between the different methods at a watershed scale.One method used the uniform slope length factor equation(USLFE)where the effects of slope irregularities(such as slope gradient,etc.)on soil erosion by water were not considered.The other method used segmented slope length factor equation(SSLFE)which considered the effects of slope irregularities on soil erosion by water.The Arc Macro Language(AML)Version 4 program for the revised universal soil loss equation(RUSLE).which uses the USLFE,was chosen to calculate the slope length factor.In a parallel analysis,the AML code of RUSLE Version 4 was modified according to the SSLFE to calculate the slope length factor.Two watersheds with different slope and gully densities were chosen.The results show that the slope length factor and soil loss using the USLFE method were lower than those using the SSLFE method,especially on downslopes watershed with more frequent steep slopes and higher gully densities.In addition,the slope length factor and soil loss calculated by the USLFE showed less spatial variation.展开更多
A raindrop impact power observation system was employed to observe the real-time raindrop impact power during a rainfall event and to analyze the corresponding rainfall characteristics.The experiments were conducted a...A raindrop impact power observation system was employed to observe the real-time raindrop impact power during a rainfall event and to analyze the corresponding rainfall characteristics.The experiments were conducted at different simulated rainfall intensities.As rainfall intensity increased,the observed impact power increased linearly indicating the power observation system would be satisfactory for characterizing rainfall erosivity.Momentum is the product of mass and velocity(Momentum=MV),which is related to the observed impact power value.Since there is no significant difference between momentum and impact power,observed impact power can represent momentum for different rainfall intensities.The relationship between momentum and the observed impact power provides a convenient way to calculate rainfall kinetic energy.The value of rainfall kinetic energy based on the observed impact power was higher than the classic rainfall kinetic energy.The rainfall impact power based kinetic energy and the classic rainfall kinetic energy showed linear correlation,which indicates that the raindrop impact power observation system can characterize rainfall kinetic energy.The article establishes a preliminary way to calculate rainfall kinetic energy by using the real-time observed momentum,providing a foundation for replacing the traditional methods for estimating kinetic energy of rainstorms.展开更多
基金funded by the Second Tibetan Plateau Scientific Expedition and Research(STEP),grant number 2021QZKK0203the National Key Research and Development Program of China,grant number 2021YFB2600105.
文摘Soil erosion on highway side-slope has been recognized as a cause of environmental damage and a potential threat to road embankments in the high-altitude permafrost regions.To assess the risk to roads and to protect them effectively,it is crucial to clarify the mechanisms governing roadside erosion.However,the cold climate and extremely vulnerable environment under permafrost conditions may result in a unique process of roadside erosion,which differs from the results of current studies conducted at lower altitudes.In this study,a field survey was conducted to investigate side-slope rill erosion along the permafrost section of a highway on the Qinghai‒Tibet Plateau of China.Variations in erosion rates have been revealed,and intense erosion risks(with an average erosion rate of 13.05 kg/m^(2)/a)have been identified on the northern side of the Tanggula Mountains.In the case of individual rills,the detailed rill morphology data indicate that the rill heads are generally close to the slope top and that erosion predominantly occurs in the upper parts of highway slopes,as they are affected by road surface runoff.In the road segment scale,the Pearson correlation and principal component analysis results revealed that the protective effect of vegetation,which was influenced by precipitation,was greater than the erosive effect of precipitation on roadside erosion.A random forest model was then adopted to quantify the importance of influencing factors,and the slope gradient was identified as the most significant factor,with a value of 0.474.Accordingly,the integrated slope and slope length index(L0.5S2)proved to be a reliable predictor,and a comprehensive model was built for highway side-slope rill erosion prediction(model efficiency=0.802).These results could be helpful for highway side-slope conservation and ecological risk prediction in alpine permafrost areas.
基金Research for this paper was funded by Program for Changjiang Scholars and Innovative Research Team in University and the Fundamental Research Funds for the Central Universities.
文摘The slope length factor is one of the parameters of the Universal Soil Loss Equation(USLE)and the Revised Universal Soil Loss Equation(RUSLE)and is sometimes calculated based on a digital elevation model(DEM).The methods for calculating the slope length factor are important because the values obtained may depend on the methods used for calculation.The purpose of this study was to compare the difference in spatial distribution of the slope length factor between the different methods at a watershed scale.One method used the uniform slope length factor equation(USLFE)where the effects of slope irregularities(such as slope gradient,etc.)on soil erosion by water were not considered.The other method used segmented slope length factor equation(SSLFE)which considered the effects of slope irregularities on soil erosion by water.The Arc Macro Language(AML)Version 4 program for the revised universal soil loss equation(RUSLE).which uses the USLFE,was chosen to calculate the slope length factor.In a parallel analysis,the AML code of RUSLE Version 4 was modified according to the SSLFE to calculate the slope length factor.Two watersheds with different slope and gully densities were chosen.The results show that the slope length factor and soil loss using the USLFE method were lower than those using the SSLFE method,especially on downslopes watershed with more frequent steep slopes and higher gully densities.In addition,the slope length factor and soil loss calculated by the USLFE showed less spatial variation.
基金supported by the National Key Technology R&D program(2011BAD31B04)also funded by the Changjiang Water Resources Commission of Ministry of Water Resources,China.
文摘A raindrop impact power observation system was employed to observe the real-time raindrop impact power during a rainfall event and to analyze the corresponding rainfall characteristics.The experiments were conducted at different simulated rainfall intensities.As rainfall intensity increased,the observed impact power increased linearly indicating the power observation system would be satisfactory for characterizing rainfall erosivity.Momentum is the product of mass and velocity(Momentum=MV),which is related to the observed impact power value.Since there is no significant difference between momentum and impact power,observed impact power can represent momentum for different rainfall intensities.The relationship between momentum and the observed impact power provides a convenient way to calculate rainfall kinetic energy.The value of rainfall kinetic energy based on the observed impact power was higher than the classic rainfall kinetic energy.The rainfall impact power based kinetic energy and the classic rainfall kinetic energy showed linear correlation,which indicates that the raindrop impact power observation system can characterize rainfall kinetic energy.The article establishes a preliminary way to calculate rainfall kinetic energy by using the real-time observed momentum,providing a foundation for replacing the traditional methods for estimating kinetic energy of rainstorms.
