The mound-making behavior of plateau zokors is one of the most important factors in remodeling meadow microtopography and causing soil erosion in the Yellow River source area of western China,but little is known about...The mound-making behavior of plateau zokors is one of the most important factors in remodeling meadow microtopography and causing soil erosion in the Yellow River source area of western China,but little is known about the effects of microtopography on particle size characteristics(PSC)of eroded sediments from the bare slopes of zokor mounds during different rainfall events.In this study,we analyzed the relationship of microtopographic features derived from laser point cloud data and PSC of eroded sediments at six simulated rainfall intensities(all lasting 60 min).The effects of microtopography on PSC of eroded sediments were studied via partial least squares regression(PLSR)and structural equation modeling(SEM).The results showed that:(1)15-20 minutes from the beginning of rainfall was the sensitive period of soil loss from the slopes,and the function relationship between the rate of sediment and runoff and rainfall intensity can better predict the development trend of soil erosion;(2)Intense erosion occurred mainly in the upper half of the zokor mound,while deposition was mainly limited to its lower half.It is suggested that diminished plateau zokor activity intensity can effectively prevent and control soil erosion;(3)The PSC of eroded sediment is dominated by silt,followed by sand,with clay being the least abundant,and the eroded sediments with a particle size of 10-20μm were sensitive and highly susceptible to rainfall erosion.This finding facilitates the understanding of the formation process of surface geomorphology and the mechanism of soil erosion;(4)The PLSR model indicates that microtopography has an extensive influence on eroded sediments during hydraulic erosion,and the SEM analysis results further confirm that the fractal dimension was the best parameter to represent the PSC of eroded sediments,whereas surface cutting degree was the dominant factor controlling the PSC of eroded sediments.These findings are crucial for predicting soil erosion in the Yellow River source area and provide a new perspective for understanding soil erosion mechanisms in alpine meadow ecosystems.展开更多
The farming-pastoral ecotone in northern China is an extremely fr@e ecological zone where wind erosion of cropland and rangeland is easy to occur. In this study, using a portable wind tunnel as a wind simulator, we co...The farming-pastoral ecotone in northern China is an extremely fr@e ecological zone where wind erosion of cropland and rangeland is easy to occur. In this study, using a portable wind tunnel as a wind simulator, we conducted field simulated wind erosion experiments combined with laboratory analysis to investigate wind erosion of soils in trampled rangeland, non-tilled cropland and tilled cropland in Yanchi County, China. The results showed that compared with rangeland, the cropland had a higher soil water holding capacity and lower soil bulk density. The wind erosion rate of trampled rangeland was much higher than those of non-tilled cropland and tilled cropland. For cropland, the wind erosion rate of the soil after tilling was surprisingly less than that of the soil before tilling. With increasing of wind speed, the volume mean diameter of the eroded sediment collected by the trough in the wind tunnel generally increased while the clay and silt content decreased for all soils. The temporal variation in wind erosion of the trampled rangeland indicated that particle entrainment and dust emission decreased exponentially with erosion time through the successive wind erosion events due to the exhaustion of erodible particles.展开更多
Delta evolution in the context of no sediment discharge has become a global concern,and an accretion-to-erosion conversion is occurring in the Yangtze estuary.This conversion could threaten Changjiang subaqueous delta...Delta evolution in the context of no sediment discharge has become a global concern,and an accretion-to-erosion conversion is occurring in the Yangtze estuary.This conversion could threaten Changjiang subaqueous delta devel-opment.Sediment erodibility is an important indicator of subaqueous delta vulnerability.However,the present and future erodibility of the Changjiang subaqueous delta remains unclear.In this study,37 short cores were collected from the Changjiang subaqueous delta,and the critical shear stress of the sediment was measured using a cohesive strength meter(CSM)and compared with estimates based on an empirical Shields diagram.The sediment erodibility was analyzed by comparing the sediment critical shear stress with the bed shear stress simulated using a numerical model(i.e.,FVCOM),and sediment activity was introduced to discuss the geomorphological change in the subaque-ous delta.The CSM-derived critical shear stress is significantly higher than that derived from the empirical Shields formula,but it better shows the erodibility of the sediment.The annual surface sediment activity ranges from 5%to 30%based on the CSM,indicating low surface erodibility.Moreover,the critical shear stress in this region increases as water depth increases,but the bed shear stress shows the opposite trend.Therefore,the erodibility of the Changjiang subaqueous delta is lower than that of the shallow area,indicating no accretion-erosion conversion or continued vertical erosion under sediment starvation in the coming decades.These findings can provide suggestions for erosion assessment and management in large river deltas under decreasing sediment discharge.展开更多
基金financially supported by the Qinghai University Graduate Student Research and Practice Innovation Project(2025-GPKY-12)Basic Research Project of Qinghai Provincial Science and Technology Department(2021-ZJ-701)+1 种基金National Natural Science Foundation of China(U23A20159,42161068)the 111 Project of China(D18013)。
文摘The mound-making behavior of plateau zokors is one of the most important factors in remodeling meadow microtopography and causing soil erosion in the Yellow River source area of western China,but little is known about the effects of microtopography on particle size characteristics(PSC)of eroded sediments from the bare slopes of zokor mounds during different rainfall events.In this study,we analyzed the relationship of microtopographic features derived from laser point cloud data and PSC of eroded sediments at six simulated rainfall intensities(all lasting 60 min).The effects of microtopography on PSC of eroded sediments were studied via partial least squares regression(PLSR)and structural equation modeling(SEM).The results showed that:(1)15-20 minutes from the beginning of rainfall was the sensitive period of soil loss from the slopes,and the function relationship between the rate of sediment and runoff and rainfall intensity can better predict the development trend of soil erosion;(2)Intense erosion occurred mainly in the upper half of the zokor mound,while deposition was mainly limited to its lower half.It is suggested that diminished plateau zokor activity intensity can effectively prevent and control soil erosion;(3)The PSC of eroded sediment is dominated by silt,followed by sand,with clay being the least abundant,and the eroded sediments with a particle size of 10-20μm were sensitive and highly susceptible to rainfall erosion.This finding facilitates the understanding of the formation process of surface geomorphology and the mechanism of soil erosion;(4)The PLSR model indicates that microtopography has an extensive influence on eroded sediments during hydraulic erosion,and the SEM analysis results further confirm that the fractal dimension was the best parameter to represent the PSC of eroded sediments,whereas surface cutting degree was the dominant factor controlling the PSC of eroded sediments.These findings are crucial for predicting soil erosion in the Yellow River source area and provide a new perspective for understanding soil erosion mechanisms in alpine meadow ecosystems.
基金supported by the National Natural Science Foundation of China (41401310, 41661003)the Science-Technology Research Project of Ningxia Environmental Protection Department
文摘The farming-pastoral ecotone in northern China is an extremely fr@e ecological zone where wind erosion of cropland and rangeland is easy to occur. In this study, using a portable wind tunnel as a wind simulator, we conducted field simulated wind erosion experiments combined with laboratory analysis to investigate wind erosion of soils in trampled rangeland, non-tilled cropland and tilled cropland in Yanchi County, China. The results showed that compared with rangeland, the cropland had a higher soil water holding capacity and lower soil bulk density. The wind erosion rate of trampled rangeland was much higher than those of non-tilled cropland and tilled cropland. For cropland, the wind erosion rate of the soil after tilling was surprisingly less than that of the soil before tilling. With increasing of wind speed, the volume mean diameter of the eroded sediment collected by the trough in the wind tunnel generally increased while the clay and silt content decreased for all soils. The temporal variation in wind erosion of the trampled rangeland indicated that particle entrainment and dust emission decreased exponentially with erosion time through the successive wind erosion events due to the exhaustion of erodible particles.
基金the Natural Science Foundation of China(No.41876092 and 42006151)the Innovation Program of Shanghai Municipal Education Commission(No.2019-01-07-00-05-E00027)the Open Research Fund of Key Laboratory of Coastal Salt Marsh Ecosystems and Resources,Ministry of Natural Resources(No.KLCSMERMNR2021001).
文摘Delta evolution in the context of no sediment discharge has become a global concern,and an accretion-to-erosion conversion is occurring in the Yangtze estuary.This conversion could threaten Changjiang subaqueous delta devel-opment.Sediment erodibility is an important indicator of subaqueous delta vulnerability.However,the present and future erodibility of the Changjiang subaqueous delta remains unclear.In this study,37 short cores were collected from the Changjiang subaqueous delta,and the critical shear stress of the sediment was measured using a cohesive strength meter(CSM)and compared with estimates based on an empirical Shields diagram.The sediment erodibility was analyzed by comparing the sediment critical shear stress with the bed shear stress simulated using a numerical model(i.e.,FVCOM),and sediment activity was introduced to discuss the geomorphological change in the subaque-ous delta.The CSM-derived critical shear stress is significantly higher than that derived from the empirical Shields formula,but it better shows the erodibility of the sediment.The annual surface sediment activity ranges from 5%to 30%based on the CSM,indicating low surface erodibility.Moreover,the critical shear stress in this region increases as water depth increases,but the bed shear stress shows the opposite trend.Therefore,the erodibility of the Changjiang subaqueous delta is lower than that of the shallow area,indicating no accretion-erosion conversion or continued vertical erosion under sediment starvation in the coming decades.These findings can provide suggestions for erosion assessment and management in large river deltas under decreasing sediment discharge.
