For the safety of railroad operations,sand barriers are utilized to mitigate wind-sand disaster effects.These disasters,characterized by multi-directional wind patterns,result in diverse angles among the barriers.In t...For the safety of railroad operations,sand barriers are utilized to mitigate wind-sand disaster effects.These disasters,characterized by multi-directional wind patterns,result in diverse angles among the barriers.In this study,using numerical simulations,we examined the behavior of High Density Polyethylene(HDPE)sheet sand barriers under different wind angles,focusing on flow field distribution,windproof efficiency,and sedimentation erosion dynamics.This study discovered that at a steady wind speed,airflow velocity varies as the angle between the airflow and the HDPE barrier changes.Specifically,a 90°angle results in the widest low-speed airflow area on the barrier’s downwind side.If the airflow is not perpendicular to the barrier,it prompts a lateral airflow movement which decreases as the angle expands.The windproof efficiency correlates directly with this angle but inversely with the wind’s speed.Notably,with a wind angle of 90°,wind speed drops by 81%.The minimum wind speed is found at 5.1H(the sand barrier height)on the barrier’s downwind side.As the angle grows,the barrier’s windproof efficiency improves,extending its protective reach.Sedimentation is most prominent on the barrier’s downwind side,as the wind angle shifts from 30°to 90°,the sand sedimentation area on the barrier’s downwind side enlarges by 14.8H.As the angle grows,sedimentation intensifies,eventually overtakes the forward erosion and enlarges the sedimentation area.展开更多
The clay–sand barriers in Minqin desert area,China,represent a pioneering windbreak and sand fixation project with a venerable history of 60 a.However,studies on evaluating the long-term effectiveness of clay–sand b...The clay–sand barriers in Minqin desert area,China,represent a pioneering windbreak and sand fixation project with a venerable history of 60 a.However,studies on evaluating the long-term effectiveness of clay–sand barriers against aeolian erosion,particularly from the perspective of surface sediment grain size,are limited and thus insufficient to ascertain the protective impact of these barriers on regional aeolian activities.This study focused on the surface sediments(topsoil of 0–3 cm depth)of clay–sand barriers in Minqin desert area to explain their erosion resistance from the perspective of surface sediment grain size.In March 2023,six clay–sand barrier sampling plots with clay–sand barriers of different deployment durations(1,5,10,20,40,and 60 a)were selected as experimental plots,and one control sampling plot was set in an adjacent mobile sandy area without sand barriers.Surface sediment samples were collected from the topsoil of each sampling plot in the study area in April 2023 and sediment grain size characteristics were analyzed.Results indicated a predominance of fine and medium sands in the surface sediments of the study area.The deployment of clay–sand barriers cultivated a fine quality in grain size composition of the regional surface sediments,increasing the average contents of very fine sand,silt,and clay by 30.82%,417.38%,and 381.52%,respectively.This trend became markedly pronounced a decade after the deployment of clay–sand barriers.The effectiveness of clay–sand barriers in erosion resistance was manifested through reduced wind velocity,the interception of sand flow,and the promotion of fine surface sediment particles.Coarser particles such as medium,coarse,and very coarse sands predominantly accumulated on the external side of the barriers,while finer particles such as fine and very fine sands concentrated in the upwind(northwest)region of the barriers.By contrast,the contents of finest particles such as silt and clay were higher in the downwind(southeast)region of the sampling plots.For the study area,the deployment of clay–sand barriers remains one of the most cost-effective engineering solutions for aeolian erosion control,with sediment grain size parameters serving as quantitative indicators for the assessment of these barriers in combating desertification.The results of this study provide a theoretical foundation for the construction of windbreak and sand fixation systems and the optimization of artificial sand control projects in arid desert areas.展开更多
Due to the restrictions on the conditions for afforestation and sand control,the development research,and application of sand barriers have accelerated in recent years,but some problems that cannot be ignored have eme...Due to the restrictions on the conditions for afforestation and sand control,the development research,and application of sand barriers have accelerated in recent years,but some problems that cannot be ignored have emerged in practice. In this paper,the functions of wind prevention,sand blocking and fixation,improving soil physical and chemical properties and increasing plant diversity of sand barriers,accretion coefficient and capacity between sand barriers,and mobile sand barriers were analyzed firstly,and then several issues that should be noted in the development and application of sand barriers were proposed. The results show that sand barriers can fix sand on the spot and maintain the stability of sand surface. As an auxiliary measure before afforestation on a mobile sand surface,they are practical and feasible. The biggest drawback of sand barriers is that they are easy to be saturated. Although they can increase plant diversity and surface roughness,they lose the function of blocking sand flow after being saturated,and their function of in-situ sand fixation also rapidly decreases with the degradation of sand barriers. Mobile sand barriers overcome the disadvantage of sand barriers being easy to be saturated to some extent,but the cost greatly increases. In terms of desertification prevention and control by plants,plants are used as sand barriers to study their functions of sand blocking and sand fixation in many researches and practices,but the more important ecological functions of adjusting temperature on sand surface and achieving surface thermodynamic equilibrium of plants are ignored.展开更多
Sand barriers are the most widely used mechanical implements for wind-blown sand control and desertification prevention.However,there is no standard quantitative cost analysis of the sizes and materials required for s...Sand barriers are the most widely used mechanical implements for wind-blown sand control and desertification prevention.However,there is no standard quantitative cost analysis of the sizes and materials required for sand barriers.In this study,based on the original land grid division model for optimal resource utilization,we calculated the total side lengths of square and regular hexagonal sand barriers with the sizes of 1.0 m×1.0 m,2.0 m×2.0 m,and 3.0 m×3.0 m in a desertified region of the Shapotou area on the southeastern edge of the Tengger Desert,China.Then,through literature review and social survey,we obtained the material cost and material utilization amount of sand barriers with different materials and sizes.Finally,we calculated the costs of square and regular hexagonal sand barriers comprised of wheat straw,corn stalk,Salix mongolica,poly lactic acid,magnesium cement,and high-density polyethylene,with the sizes of 1.0 m×1.0 m,2.0 m×2.0 m,and 3.0 m×3.0 m.The results show that the material cost of regular hexagonal corn stalk sand barriers with the size of 3.0 m×3.0 m is the lowest,while the material cost of square magnesium cement sand barriers with the size of 1.0 m×1.0 m is the highest.When using the same material,the cost of regular hexagonal sand barriers is lower than that of square sand barriers with the same size.When using the same size,the cost of sand barriers with corn stalk material is lower than that of sand barriers with other materials.Based on the above analysis,we can conclude that the economic benefits of regular hexagonal sand barriers are greater than those of square sand barriers.This study provides a theoretical basis for accurately calculating the material cost of sand barriers,particularly for the estimated cost of mechanized sand barrier engineering projects.展开更多
The morphological evolution of the sand barrier in the Anhaiao coastal zone of Pingtan from 1996 to 2018 was studied.Tidal correction was used to refine the location of the coastline.A standard deviation ellipse metho...The morphological evolution of the sand barrier in the Anhaiao coastal zone of Pingtan from 1996 to 2018 was studied.Tidal correction was used to refine the location of the coastline.A standard deviation ellipse method was applied to further analyze the movement of the barrier head with the axis and rotation angle.A natural neighbor interpolation(NNI)method was carried out to calculate the terrain of the intertidal area,and the erosion and deposition characteristics were illustrated based on the terrain.The results showed that the northern part of the sand barrier facing the lagoon area was deposited over the whole studied period,while erosion has always occurred in the southern part of the sand barrier facing the open sea.The erosion and deposition were slightly different on both sides of the barrier head due to hydrodynamic turbulence.The middle sand barrier moved 102.60 m away from its original location in 1996,and the end of the barrier moved 65.45 m.The head of the sand barrier continued moving 379 m to the northwest.Consequently,the preliminary morphological evolution of the sand barrier corresponding to the distance and direction of movement was detected.展开更多
基金financially supported by the Natural Science Foundation of Gansu Province,China(22JR5RA050,20JR10RA231)the fellowship of the China Postdoctoral Science Foundation(2021M703466)the Basic Research Innovation Group Project of Gansu Province,China(21JR7RA347).
文摘For the safety of railroad operations,sand barriers are utilized to mitigate wind-sand disaster effects.These disasters,characterized by multi-directional wind patterns,result in diverse angles among the barriers.In this study,using numerical simulations,we examined the behavior of High Density Polyethylene(HDPE)sheet sand barriers under different wind angles,focusing on flow field distribution,windproof efficiency,and sedimentation erosion dynamics.This study discovered that at a steady wind speed,airflow velocity varies as the angle between the airflow and the HDPE barrier changes.Specifically,a 90°angle results in the widest low-speed airflow area on the barrier’s downwind side.If the airflow is not perpendicular to the barrier,it prompts a lateral airflow movement which decreases as the angle expands.The windproof efficiency correlates directly with this angle but inversely with the wind’s speed.Notably,with a wind angle of 90°,wind speed drops by 81%.The minimum wind speed is found at 5.1H(the sand barrier height)on the barrier’s downwind side.As the angle grows,the barrier’s windproof efficiency improves,extending its protective reach.Sedimentation is most prominent on the barrier’s downwind side,as the wind angle shifts from 30°to 90°,the sand sedimentation area on the barrier’s downwind side enlarges by 14.8H.As the angle grows,sedimentation intensifies,eventually overtakes the forward erosion and enlarges the sedimentation area.
基金the National Natural Science Foundation of China(42230720,32160410,42167069)the Gansu Key Research and Development Program(22YF7FA078,GZTZ20240415)Gansu Province Forestry and Grassland Science and Technology Innovation Project(LCCX202303).
文摘The clay–sand barriers in Minqin desert area,China,represent a pioneering windbreak and sand fixation project with a venerable history of 60 a.However,studies on evaluating the long-term effectiveness of clay–sand barriers against aeolian erosion,particularly from the perspective of surface sediment grain size,are limited and thus insufficient to ascertain the protective impact of these barriers on regional aeolian activities.This study focused on the surface sediments(topsoil of 0–3 cm depth)of clay–sand barriers in Minqin desert area to explain their erosion resistance from the perspective of surface sediment grain size.In March 2023,six clay–sand barrier sampling plots with clay–sand barriers of different deployment durations(1,5,10,20,40,and 60 a)were selected as experimental plots,and one control sampling plot was set in an adjacent mobile sandy area without sand barriers.Surface sediment samples were collected from the topsoil of each sampling plot in the study area in April 2023 and sediment grain size characteristics were analyzed.Results indicated a predominance of fine and medium sands in the surface sediments of the study area.The deployment of clay–sand barriers cultivated a fine quality in grain size composition of the regional surface sediments,increasing the average contents of very fine sand,silt,and clay by 30.82%,417.38%,and 381.52%,respectively.This trend became markedly pronounced a decade after the deployment of clay–sand barriers.The effectiveness of clay–sand barriers in erosion resistance was manifested through reduced wind velocity,the interception of sand flow,and the promotion of fine surface sediment particles.Coarser particles such as medium,coarse,and very coarse sands predominantly accumulated on the external side of the barriers,while finer particles such as fine and very fine sands concentrated in the upwind(northwest)region of the barriers.By contrast,the contents of finest particles such as silt and clay were higher in the downwind(southeast)region of the sampling plots.For the study area,the deployment of clay–sand barriers remains one of the most cost-effective engineering solutions for aeolian erosion control,with sediment grain size parameters serving as quantitative indicators for the assessment of these barriers in combating desertification.The results of this study provide a theoretical foundation for the construction of windbreak and sand fixation systems and the optimization of artificial sand control projects in arid desert areas.
基金Supported by National Natural Science Foundation of China(41671528)
文摘Due to the restrictions on the conditions for afforestation and sand control,the development research,and application of sand barriers have accelerated in recent years,but some problems that cannot be ignored have emerged in practice. In this paper,the functions of wind prevention,sand blocking and fixation,improving soil physical and chemical properties and increasing plant diversity of sand barriers,accretion coefficient and capacity between sand barriers,and mobile sand barriers were analyzed firstly,and then several issues that should be noted in the development and application of sand barriers were proposed. The results show that sand barriers can fix sand on the spot and maintain the stability of sand surface. As an auxiliary measure before afforestation on a mobile sand surface,they are practical and feasible. The biggest drawback of sand barriers is that they are easy to be saturated. Although they can increase plant diversity and surface roughness,they lose the function of blocking sand flow after being saturated,and their function of in-situ sand fixation also rapidly decreases with the degradation of sand barriers. Mobile sand barriers overcome the disadvantage of sand barriers being easy to be saturated to some extent,but the cost greatly increases. In terms of desertification prevention and control by plants,plants are used as sand barriers to study their functions of sand blocking and sand fixation in many researches and practices,but the more important ecological functions of adjusting temperature on sand surface and achieving surface thermodynamic equilibrium of plants are ignored.
基金supported by the Research Program of Technology and Demonstration of Desert Margin Expansion Zone Stabilization for Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences(XDA23060201)。
文摘Sand barriers are the most widely used mechanical implements for wind-blown sand control and desertification prevention.However,there is no standard quantitative cost analysis of the sizes and materials required for sand barriers.In this study,based on the original land grid division model for optimal resource utilization,we calculated the total side lengths of square and regular hexagonal sand barriers with the sizes of 1.0 m×1.0 m,2.0 m×2.0 m,and 3.0 m×3.0 m in a desertified region of the Shapotou area on the southeastern edge of the Tengger Desert,China.Then,through literature review and social survey,we obtained the material cost and material utilization amount of sand barriers with different materials and sizes.Finally,we calculated the costs of square and regular hexagonal sand barriers comprised of wheat straw,corn stalk,Salix mongolica,poly lactic acid,magnesium cement,and high-density polyethylene,with the sizes of 1.0 m×1.0 m,2.0 m×2.0 m,and 3.0 m×3.0 m.The results show that the material cost of regular hexagonal corn stalk sand barriers with the size of 3.0 m×3.0 m is the lowest,while the material cost of square magnesium cement sand barriers with the size of 1.0 m×1.0 m is the highest.When using the same material,the cost of regular hexagonal sand barriers is lower than that of square sand barriers with the same size.When using the same size,the cost of sand barriers with corn stalk material is lower than that of sand barriers with other materials.Based on the above analysis,we can conclude that the economic benefits of regular hexagonal sand barriers are greater than those of square sand barriers.This study provides a theoretical basis for accurately calculating the material cost of sand barriers,particularly for the estimated cost of mechanized sand barrier engineering projects.
基金The Key Projects of Philosophy and Social Sciences ResearchMinistry of Education under contract No.18JZD059
文摘The morphological evolution of the sand barrier in the Anhaiao coastal zone of Pingtan from 1996 to 2018 was studied.Tidal correction was used to refine the location of the coastline.A standard deviation ellipse method was applied to further analyze the movement of the barrier head with the axis and rotation angle.A natural neighbor interpolation(NNI)method was carried out to calculate the terrain of the intertidal area,and the erosion and deposition characteristics were illustrated based on the terrain.The results showed that the northern part of the sand barrier facing the lagoon area was deposited over the whole studied period,while erosion has always occurred in the southern part of the sand barrier facing the open sea.The erosion and deposition were slightly different on both sides of the barrier head due to hydrodynamic turbulence.The middle sand barrier moved 102.60 m away from its original location in 1996,and the end of the barrier moved 65.45 m.The head of the sand barrier continued moving 379 m to the northwest.Consequently,the preliminary morphological evolution of the sand barrier corresponding to the distance and direction of movement was detected.
