Recently,significant progress has been made in conceptually describing the dynamic aspects of coarse particle entrainment,which has been explored experimentally for open channel flows.The aim of this study is to exten...Recently,significant progress has been made in conceptually describing the dynamic aspects of coarse particle entrainment,which has been explored experimentally for open channel flows.The aim of this study is to extend the application of energy criterion to the low mobility aeolian transport of solids(including both natural sediment and anthropogenic debris such as plastics),ranging from incomplete(rocking)to full(rolling)entrainments.This is achieved by linking particle movements to energetic flow events,which are defined as flow structures with the ability to work on particles,setting them into motion.It is hypothesized that such events should impart sufficient energy to the particles,above a certain threshold value.The concept’s validity is demonstrated experimentally,using a wind tunnel and laser distance sensor to capture the dynamics of an individual target particle,exposed on a rough bed surface.Measurements are acquired at a high spatiotemporal resolution,and synchronously with the instantaneous air velocity at an appropriate distance upwind of the target particle,using a hot film anemometer.This enables the association of flow events with rocking and rolling entrainments.Furthermore,it is shown that rocking and rolling may have distinct energy thresholds.Estimates of the energy transfer efficiency,normalized by the drag coefficient,range over an order of magnitude(from about 0.001 to 0.0048 for rocking,up to about 0.01,for incipient rolling).The proposed event-based theoretical framework is a novel approach to characterizing the energy imparted from the wind to the soil surface and could have potential implications for modelling intermittent creep transport of coarse particles and related aeolian bedforms.展开更多
A macro-tidal tropical estuary with high fluvial discharge is characterized by both fragility and remarkable dynamism.This study utilizes the Salween River Delta(SRD)as a case example to examine the interplay between ...A macro-tidal tropical estuary with high fluvial discharge is characterized by both fragility and remarkable dynamism.This study utilizes the Salween River Delta(SRD)as a case example to examine the interplay between morphology and vegetation under similar tidal conditions.Our analysis of correlations and inferences revealed several significant trends in the SRD:(1)an overall expansion of land area and intertidal vegetation,with the most pronounced changes occurring in the eastern sector;(2)the predominance of river discharge influencing the southwestern and northern sectors,contrasted with the primary impact of storm surges in the eastern sector;and(3)three distinct causal relationships among estuarine morphology,vegetation,storm surges,and river discharge:a direct model where river discharge shapes estuarine morphology,a progressive model in which river discharge affects vegetation distribution,subsequently influencing estuarine morphology,and a hybrid model where storm surges directly impact vegetation and indirectly modify its distribution through changes in estuarine morphology.The stability of sediment supply and the role of intertidal vegetation are crucial for the continuous seaward advance,providing a vital foundation for the protection and development of estuarine deltas.展开更多
0 INTRODUCTION The Qilian Mountain Belt,at the forefront of the Tibetan Plateau's expansion,offers key insights into the plateau's tectonic deformation(Zuza et al.,2018;Zheng et al.,2010;Zhang et al.,2004;Tapp...0 INTRODUCTION The Qilian Mountain Belt,at the forefront of the Tibetan Plateau's expansion,offers key insights into the plateau's tectonic deformation(Zuza et al.,2018;Zheng et al.,2010;Zhang et al.,2004;Tapponnier et al.,2001;Meyer et al.,1998).The northwest-trending mountain ranges in the Qilian Shan(“Shan”means“Mountain”in Chinese)have significantly influenced this deformation(Zheng et al.,2013).展开更多
The Upper Devonian Buchan Formation in the Central North Sea is a typical terrestrial deposit and predominantly comprises fine to medium-grained sandstones with occasional conglomerates and mudstones. The Buchan Forma...The Upper Devonian Buchan Formation in the Central North Sea is a typical terrestrial deposit and predominantly comprises fine to medium-grained sandstones with occasional conglomerates and mudstones. The Buchan Formation has been previously described as being made up mostly of braided fluvial sandstones;however, this study confirms the presence and significance of aeolian sandstones within this fluvial-dominated sequence. Facies architecture is investigated through analogue outcrop study, well log curves and numerical facies modelling, and the results show contrasting differences between fluvial and aeolian facies. The fluvial facies is composed of multiple superimposed and sand-dominated fining-upward cycles in the vertical direction, and laterally an individual cycle has a large width/thickness ratio but is smaller than the field scale. However, the high channel deposition proportion (CDP, average value = 72%) in fluvial-dominated intervals means that it is likely all the sand bodies are interconnected. Aeolian facies comprise superimposed dune and interdune depositions and can be laterally correlated over considerable distances (over 1 km). Although the aeolian sandstones are volumetrically minor (approx. 30%) within the whole Buchan Formation, they have very high porosity and permeability (14.1% - 28%, 27 - 5290 mD) and therefore are excellent potential reservoirs. The fluvial sandstones are significantly cemented by quartz overgrowth and dolomite and by comparison with the aeolian sandstones are poor reservoirs. Aeolian sandstones can be differentiated from fluvial sandstones using several features: pin-stripe lamentation, good sorting, high visible porosity, friable nature and lack of muddy or conglomeratic contents;these characteristics allow aeolian sandstones can be tentatively recognized by low gamma ray values, high sonic transit time and low density in uncored wells. The thin, laterally correlatable and permeable aeolian sandstones within the Buchan Formation are effective reservoirs and could form important exploration targets when the Devonian is targeted elsewhere in the North Sea.展开更多
Using aeolian sand(AS)for goaf backfilling allows coordination of green mining and AS control.Cemented AS backfill(CASB)exhibits brittle fracture.Polypropylene(PP)fibers are good toughening materials.When the tougheni...Using aeolian sand(AS)for goaf backfilling allows coordination of green mining and AS control.Cemented AS backfill(CASB)exhibits brittle fracture.Polypropylene(PP)fibers are good toughening materials.When the toughening effect of fibers is analyzed,their influence on the slurry conveying performance should also be considered.Additionally,cement affects the interactions among the hydration products,fibers,and aggregates.In this study,the effects of cement content(8wt%,9wt%,and 10wt%)and PP fiber length(6,9,and 12 mm)and dosage(0.05wt%,0.1wt%,0.15wt%,0.2wt%,and 0.25wt%)on fluidity and mechanical properties of the fibertoughened CASB(FCASB)were analyzed.The results indicated that with increases in the three aforementioned factors,the slump flow decreased,while the rheological parameters increased.Uniaxial compressive strength(UCS)increased with the increase of cement content and fiber length,and with an increase in fiber dosage,it first increased and then decreased.The strain increased with the increase of fiber dosage and length.The effect of PP fibers became more pronounced with the increase of cement content.Digital image correlation(DIC)test results showed that the addition of fibers can restrain the peeling of blocks and the expansion of fissure,and reduce the stress concentration of the FCASB.Scanning electron microscopy(SEM)test indicated that the functional mechanisms of fibers mainly involved the interactions of fibers with the hydration products and matrix and the spatial distribution of fibers.On the basis of single-factor analysis,the response surface method(RSM)was used to analyze the effects of the three aforementioned factors and their interaction terms on the UCS.The influence surface of the two-factor interaction terms and the three-dimensional scatter plot of the three-factor coupling were established.In conclusion,the response law of the FCASB properties under the effects of cement and PP fibers were obtained,which provides theoretical and engineering guidance for FCASB filling.展开更多
Fast water can cause extraordinary bedload transport.Of the record floods considered here,the Jul.26,2022 urban flash flood on the upper River des Peres,St.Louis,Missouri provides particularly well-constrained data on...Fast water can cause extraordinary bedload transport.Of the record floods considered here,the Jul.26,2022 urban flash flood on the upper River des Peres,St.Louis,Missouri provides particularly well-constrained data on flow conditions associated with large block movement.Field measurements and a detailed lidar survey show that concrete slabs as large as 3.0×2.5×0.33 m^(3)were moved from the open channel to reside 215 to 450 m inside a 6.5 m-diameter drainage tunnel,some to become part of a 10-m long imbricated pile.Peak flows of 160 m^(3)/s were recorded at a gauging station located only 1.6 km upstream of the tunnel entrance,which provides a good estimate of 4.2 m/s for the peak flow velocity in the tunnel.Available observational data and a new theoretical analysis show that the radius of large boulders that can be moved by flowing water is directly proportional to the velocity head.展开更多
At present,the architecture modeling method of fluvial reservoirs are still developing.Traditional methods usually use grids to characterize architecture interbeds within the reservoir.Due to the thin thickness of thi...At present,the architecture modeling method of fluvial reservoirs are still developing.Traditional methods usually use grids to characterize architecture interbeds within the reservoir.Due to the thin thickness of this type of the interlayers,the number of the model grids must be greatly expanded.The number of grids in the tens of millions often makes an expensive computation;however,upscaling the model will generate a misleading model.The above confusion is the major reason that restricts the largescale industrialization of fluvial reservoir architecture models in oilfield development and production.Therefore,this paper explores an intelligent architecture modeling method for multilevel fluvial reservoirs based on architecture interface and element.Based on the superpositional relationship of different architectural elements within the fluvial reservoir,this method uses a combination of multilevel interface constraints and non-uniform grid techniques to build a high-resolution 3D geological model for reservoir architecture.Through the grid upscaling technology of heterogeneous architecture elements,different upscaling densities are given to the lateral-accretion bedding and lateral-accretion bodies to simplify the model gridding.This new method greatly reduces the number of model grids while ensuring the accuracy of lateral-accretion bedding models,laying a foundation for large-scale numerical simulation of the subsequent industrialization of the architecture model.This method has been validated in A layer of X oilfield with meandering fluvial channel sands as reservoirs and B layer of Y oilfield with braided river sands as reservoirs.The simulation results show that it has a higher accuracy of production history matching and remaining oil distribution forecast of the targeted sand body.The numerical simulation results show that in the actual development process of oilfield,the injected water will not displace oil in a uniform diffusive manner as traditionally assumed,but in a more complex pattern with oil in upper part of sand body being left behind as residual oil due to the influences of different levels of architecture interfaces.This investigation is important to guiding reservoir evaluation,remaining oil analysis,profile control and potential tapping and well pattern adjustment.展开更多
The Shiyang River is an important ecological pillar in northwest China,sustaining Minqin oasis and its surrounding society.However,the basin has long been plagued by water scarcity and ecological fragility.Although th...The Shiyang River is an important ecological pillar in northwest China,sustaining Minqin oasis and its surrounding society.However,the basin has long been plagued by water scarcity and ecological fragility.Although the river classification is critical for understanding the complexity,diversity,and ecological functions of rivers,and the foundation of river management and watershed ecological restoration,it has not received adequate attention in this region.To obtain a deeper and comprehensive understanding of the Shiyang River,this study utilizes the Rosgen stream classification system to assess the river morphology,geomorphic features,and hydrologic processes.The results showed that seven first-level and fourteen second-level river types can be identified along 53 river sections of the Shiyang River.Further comparison analysis on the hydrologic parameters for each river type demonstrated a strong positive correlation between discharge and all river parameters.As discharge increased,channels with moderate to high width/depth ratios experienced significant lateral adjustments.A consistent channel gradient,coupled with higher discharge,facilitated the transition from single to multiple channels.Braiding tendencies were more pronounced in rivers where riverbeds were wider and shallower with higher stream power.Additionally,water-flow shear stress decreased with the increase in the width/depth ratio.This study offered critical insights into the Shiyang River’s forms and processes and for the river management and ecological restoration practices.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
基金supported by the National Natural Science Foundation of China (Grants Nos.41171005,41071005,12272344,and 12350710176)the Ministry of Science and Technology of the People’s Republic of China (Grant No.2013CB956000).
文摘Recently,significant progress has been made in conceptually describing the dynamic aspects of coarse particle entrainment,which has been explored experimentally for open channel flows.The aim of this study is to extend the application of energy criterion to the low mobility aeolian transport of solids(including both natural sediment and anthropogenic debris such as plastics),ranging from incomplete(rocking)to full(rolling)entrainments.This is achieved by linking particle movements to energetic flow events,which are defined as flow structures with the ability to work on particles,setting them into motion.It is hypothesized that such events should impart sufficient energy to the particles,above a certain threshold value.The concept’s validity is demonstrated experimentally,using a wind tunnel and laser distance sensor to capture the dynamics of an individual target particle,exposed on a rough bed surface.Measurements are acquired at a high spatiotemporal resolution,and synchronously with the instantaneous air velocity at an appropriate distance upwind of the target particle,using a hot film anemometer.This enables the association of flow events with rocking and rolling entrainments.Furthermore,it is shown that rocking and rolling may have distinct energy thresholds.Estimates of the energy transfer efficiency,normalized by the drag coefficient,range over an order of magnitude(from about 0.001 to 0.0048 for rocking,up to about 0.01,for incipient rolling).The proposed event-based theoretical framework is a novel approach to characterizing the energy imparted from the wind to the soil surface and could have potential implications for modelling intermittent creep transport of coarse particles and related aeolian bedforms.
基金National Natural Science Foundation of China,No.41906148,No.42271086Rejuvenating Yunnan Talents Support Plan Young Talent Program,No.XDYC-QNRC-2023-0322。
文摘A macro-tidal tropical estuary with high fluvial discharge is characterized by both fragility and remarkable dynamism.This study utilizes the Salween River Delta(SRD)as a case example to examine the interplay between morphology and vegetation under similar tidal conditions.Our analysis of correlations and inferences revealed several significant trends in the SRD:(1)an overall expansion of land area and intertidal vegetation,with the most pronounced changes occurring in the eastern sector;(2)the predominance of river discharge influencing the southwestern and northern sectors,contrasted with the primary impact of storm surges in the eastern sector;and(3)three distinct causal relationships among estuarine morphology,vegetation,storm surges,and river discharge:a direct model where river discharge shapes estuarine morphology,a progressive model in which river discharge affects vegetation distribution,subsequently influencing estuarine morphology,and a hybrid model where storm surges directly impact vegetation and indirectly modify its distribution through changes in estuarine morphology.The stability of sediment supply and the role of intertidal vegetation are crucial for the continuous seaward advance,providing a vital foundation for the protection and development of estuarine deltas.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(No.2019QZKK0901)the State Key Laboratory of Earthquake Dynamics(No.LED2023B04)+1 种基金the National Natural Science Foundation of China(Nos.42272242,W2411033,W2521003)the Science and Technology Plan of Gansu Province(No.22JR11RA088)。
文摘0 INTRODUCTION The Qilian Mountain Belt,at the forefront of the Tibetan Plateau's expansion,offers key insights into the plateau's tectonic deformation(Zuza et al.,2018;Zheng et al.,2010;Zhang et al.,2004;Tapponnier et al.,2001;Meyer et al.,1998).The northwest-trending mountain ranges in the Qilian Shan(“Shan”means“Mountain”in Chinese)have significantly influenced this deformation(Zheng et al.,2013).
文摘The Upper Devonian Buchan Formation in the Central North Sea is a typical terrestrial deposit and predominantly comprises fine to medium-grained sandstones with occasional conglomerates and mudstones. The Buchan Formation has been previously described as being made up mostly of braided fluvial sandstones;however, this study confirms the presence and significance of aeolian sandstones within this fluvial-dominated sequence. Facies architecture is investigated through analogue outcrop study, well log curves and numerical facies modelling, and the results show contrasting differences between fluvial and aeolian facies. The fluvial facies is composed of multiple superimposed and sand-dominated fining-upward cycles in the vertical direction, and laterally an individual cycle has a large width/thickness ratio but is smaller than the field scale. However, the high channel deposition proportion (CDP, average value = 72%) in fluvial-dominated intervals means that it is likely all the sand bodies are interconnected. Aeolian facies comprise superimposed dune and interdune depositions and can be laterally correlated over considerable distances (over 1 km). Although the aeolian sandstones are volumetrically minor (approx. 30%) within the whole Buchan Formation, they have very high porosity and permeability (14.1% - 28%, 27 - 5290 mD) and therefore are excellent potential reservoirs. The fluvial sandstones are significantly cemented by quartz overgrowth and dolomite and by comparison with the aeolian sandstones are poor reservoirs. Aeolian sandstones can be differentiated from fluvial sandstones using several features: pin-stripe lamentation, good sorting, high visible porosity, friable nature and lack of muddy or conglomeratic contents;these characteristics allow aeolian sandstones can be tentatively recognized by low gamma ray values, high sonic transit time and low density in uncored wells. The thin, laterally correlatable and permeable aeolian sandstones within the Buchan Formation are effective reservoirs and could form important exploration targets when the Devonian is targeted elsewhere in the North Sea.
基金financially supported by the National Natural Science Foundation of China(No.52174095)the Top Innovative Talents Cultivation Fund for Doctoral Postgraduates(No.BBJ2023054).
文摘Using aeolian sand(AS)for goaf backfilling allows coordination of green mining and AS control.Cemented AS backfill(CASB)exhibits brittle fracture.Polypropylene(PP)fibers are good toughening materials.When the toughening effect of fibers is analyzed,their influence on the slurry conveying performance should also be considered.Additionally,cement affects the interactions among the hydration products,fibers,and aggregates.In this study,the effects of cement content(8wt%,9wt%,and 10wt%)and PP fiber length(6,9,and 12 mm)and dosage(0.05wt%,0.1wt%,0.15wt%,0.2wt%,and 0.25wt%)on fluidity and mechanical properties of the fibertoughened CASB(FCASB)were analyzed.The results indicated that with increases in the three aforementioned factors,the slump flow decreased,while the rheological parameters increased.Uniaxial compressive strength(UCS)increased with the increase of cement content and fiber length,and with an increase in fiber dosage,it first increased and then decreased.The strain increased with the increase of fiber dosage and length.The effect of PP fibers became more pronounced with the increase of cement content.Digital image correlation(DIC)test results showed that the addition of fibers can restrain the peeling of blocks and the expansion of fissure,and reduce the stress concentration of the FCASB.Scanning electron microscopy(SEM)test indicated that the functional mechanisms of fibers mainly involved the interactions of fibers with the hydration products and matrix and the spatial distribution of fibers.On the basis of single-factor analysis,the response surface method(RSM)was used to analyze the effects of the three aforementioned factors and their interaction terms on the UCS.The influence surface of the two-factor interaction terms and the three-dimensional scatter plot of the three-factor coupling were established.In conclusion,the response law of the FCASB properties under the effects of cement and PP fibers were obtained,which provides theoretical and engineering guidance for FCASB filling.
文摘Fast water can cause extraordinary bedload transport.Of the record floods considered here,the Jul.26,2022 urban flash flood on the upper River des Peres,St.Louis,Missouri provides particularly well-constrained data on flow conditions associated with large block movement.Field measurements and a detailed lidar survey show that concrete slabs as large as 3.0×2.5×0.33 m^(3)were moved from the open channel to reside 215 to 450 m inside a 6.5 m-diameter drainage tunnel,some to become part of a 10-m long imbricated pile.Peak flows of 160 m^(3)/s were recorded at a gauging station located only 1.6 km upstream of the tunnel entrance,which provides a good estimate of 4.2 m/s for the peak flow velocity in the tunnel.Available observational data and a new theoretical analysis show that the radius of large boulders that can be moved by flowing water is directly proportional to the velocity head.
文摘At present,the architecture modeling method of fluvial reservoirs are still developing.Traditional methods usually use grids to characterize architecture interbeds within the reservoir.Due to the thin thickness of this type of the interlayers,the number of the model grids must be greatly expanded.The number of grids in the tens of millions often makes an expensive computation;however,upscaling the model will generate a misleading model.The above confusion is the major reason that restricts the largescale industrialization of fluvial reservoir architecture models in oilfield development and production.Therefore,this paper explores an intelligent architecture modeling method for multilevel fluvial reservoirs based on architecture interface and element.Based on the superpositional relationship of different architectural elements within the fluvial reservoir,this method uses a combination of multilevel interface constraints and non-uniform grid techniques to build a high-resolution 3D geological model for reservoir architecture.Through the grid upscaling technology of heterogeneous architecture elements,different upscaling densities are given to the lateral-accretion bedding and lateral-accretion bodies to simplify the model gridding.This new method greatly reduces the number of model grids while ensuring the accuracy of lateral-accretion bedding models,laying a foundation for large-scale numerical simulation of the subsequent industrialization of the architecture model.This method has been validated in A layer of X oilfield with meandering fluvial channel sands as reservoirs and B layer of Y oilfield with braided river sands as reservoirs.The simulation results show that it has a higher accuracy of production history matching and remaining oil distribution forecast of the targeted sand body.The numerical simulation results show that in the actual development process of oilfield,the injected water will not displace oil in a uniform diffusive manner as traditionally assumed,but in a more complex pattern with oil in upper part of sand body being left behind as residual oil due to the influences of different levels of architecture interfaces.This investigation is important to guiding reservoir evaluation,remaining oil analysis,profile control and potential tapping and well pattern adjustment.
基金funded by The Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK0205)the National Natural Science Foundation of China(Grant No.42171002)the Science and technology Project of Tibet Autonomous Region(Grant No.XZ202401ZY0069).
文摘The Shiyang River is an important ecological pillar in northwest China,sustaining Minqin oasis and its surrounding society.However,the basin has long been plagued by water scarcity and ecological fragility.Although the river classification is critical for understanding the complexity,diversity,and ecological functions of rivers,and the foundation of river management and watershed ecological restoration,it has not received adequate attention in this region.To obtain a deeper and comprehensive understanding of the Shiyang River,this study utilizes the Rosgen stream classification system to assess the river morphology,geomorphic features,and hydrologic processes.The results showed that seven first-level and fourteen second-level river types can be identified along 53 river sections of the Shiyang River.Further comparison analysis on the hydrologic parameters for each river type demonstrated a strong positive correlation between discharge and all river parameters.As discharge increased,channels with moderate to high width/depth ratios experienced significant lateral adjustments.A consistent channel gradient,coupled with higher discharge,facilitated the transition from single to multiple channels.Braiding tendencies were more pronounced in rivers where riverbeds were wider and shallower with higher stream power.Additionally,water-flow shear stress decreased with the increase in the width/depth ratio.This study offered critical insights into the Shiyang River’s forms and processes and for the river management and ecological restoration practices.
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.
