Soil erosion and its causes in high-filling body:A case study of a valley area on the Loess Plateau,China

Large-scale land consolidation projects(LCPs)have been carried out on the Loess Plateau to increase the area of agriculture land.The newly created land is prone to soil erosion under the effects of water and gravity.Taking a typical high-filling body(HFB)formed by LCPs in Yan’an,China as the subject,this study comprehensively investigated the types and causes of soil erosion with multiple methods of field investigation,on-site monitoring and laboratory tests.Results showed that the HFB presented a composite pattern of soil erosion with multiple types mainly including underground erosion,mixed water-gravity erosion,seepage erosion,and scouring erosion.The type of erosion varied spatially in different parts of the HFB depending on the dominant factors,mainly including the groundwater state,rainfall,runoff,gravity action,topography,and soil erodibility.The underground erosion mainly occurred at the positions with higher groundwater level and larger hydraulic gradient,while scouring erosion mainly occurred at the positions with extensive interactions of surface runoff,channel slope gradient and soil properties.And near the leading edge of the top of the slope,a band of mixed watergravity erosion occurred owing to the effects of water and gravity.In addition,nearly saturated soils at the toe of HFB displayed groundwater exfiltration and slope-face slumping.Based on our findings on the causes and variation of soil erosion for the HFB,we proposed the following erosion prevention and control measures to protect the LCPs on the Loess Plateau:to construct drainage ditches and blind ditches to form a complete drainage system,plant alfalfa on the top platform to increase rainfall interception and reduce surface runoff,set seepage ditches and plant deep-rooted plants at the toe of the slope to improve slope toe stability,monitor groundwater level and slope deformation to learn the erosion dynamics and slope stability,and optimize the geometry of HFB such as the slope gradient and slope steps to reduce soil erosion.

Stability of loess high-fill slope based on monitored soil moisture changes

This paper aims to assess the influence of moisture content changes during rainfall on the stability of loess high-fill slopes by taking a loess high-fill slope in Lanzhou City as an example.First,according to the moisture content monitoring data collected from a slope online monitoring system,direct shear tests were performed on soil samples of different moisture content to determine the relationship between the shear strength parameters and moisture content.Next,a coupled hydro-mechanical model with soil shear strength related to moisture content was established and used to analyze 16 working conditions with various rainfall intensities and durations for two cases:shear strength parameters from the site exploration report and those from this study.Finally,the results from the two cases were compared regarding the changes in stresses and displacements after rainfall infiltration to analyze the influence of moisture content on the stability of loess high-fill slopes.The conclusions are as follows:(1)Segmental relationship equations of cohesion and angle of internal friction were established for loess with various moisture content.(2)Under the conditions of different rainfall intensities,significant differences were observed in the trends of slope stress and displacement changes.(3)The slope displacement occurred in the shallow soil layer within about 12.5 m from the slope top,and the plastic strain concentrated in the soil layer within about 6 m from the slope top.(4)The results of slope stability analyses based on moisture content monitoring data are more in line with the observed.

Simulation on slope uncertainty derived from DEMs at different resolution levels:a case study in the Loess Plateau

Slope is one of the crucial terrain variables in spatial analysis and land use planning, especially in the Loess Plateau area of China which is suffering from serious soil erosion. DEM based slope extracting method has been widely accepted and applied in practice. However slope accuracy derived from this method usually does not match with its popularity. A quantitative simulation to slope data uncertainty is important not only theoretically but also necessarily to applications. This paper focuses on how resolution and terrain complexity impact on the accuracy of mean slope extracted from DEMs of different resolutions in the Loess Plateau of China. Six typical geomorphologic areas are selected as test areas, representing different terrain types from smooth to rough. Their DEMs are produced from digitizing contours of 1:10,000 scale topographic maps. Field survey results show that 5 m should be the most suitable grid size for representing slope in the Loess Plateau area. Comparative and math-simulation methodology was employed for data processing and analysis. A linear correlativity between mean slope and DEM resolution was found at all test areas, but their regression coefficients related closely with the terrain complexity of the test areas. If taking stream channel density to represent terrain complexity, mean slope error could be regressed against DEM resolution (X) and stream channel density (S) at 8 resolution levels and expressed as (0.00158+0.031S-0.0325)X-0.0045S2-0.155S+0.1625, with a R2 value of over 0.98. Practical tests also show an effective result of this model in applications. The new development methodology applied in this study should be helpful to similar researches in spatial data uncertainty investigation.

Numerical study on settlement of high-fill airports in collapsible loess geomaterials:A case study of Lüliang Airport in Shanxi Province,China

Foundation settlement is of great significance for high-fill engineering in collapsible loess areas.To predict the construction settlement of Lüliang Airport located in Shanxi Province,China,a plane strain finite element method considering the linear variation in the modulus,was carried out in this paper based on the results of geotechnical tests.The stress and deformation of four typical sections caused by layered fill are simulated,and then the settlement of the high-fill airport is calculated and analyzed by inputting three sets of parameters.The relative soft parameters of loess geomaterials produce more settlement than the relatively hard parameters.The thicker the filling body is,the greater the settlement is.The filling body constrained by mountains on both sides produces less settlement than the filling body constrained by a mountain on only one side even the filling thickness is almost the same.The settlement caused by the original subbase accounts for 56%−77%of the total settlement,while the fill soils themselves accounts for 23%−44%of the total settlement,which is approximately consistent with the field monitoring results.It provides a good reference for predicting the settlement of similar high-fill engineering.

Analysis of Comprehensive Benefits of Transforming Slope Farmland to Terraces on the Loess Plateau:A Case Study of the Yangou Watershed in Northern Shaanxi Province,China

De-farming slope farmland has been an effective measure in recent years to improve environment and prevent soil and water loss on the Loess Plateau.There are different views about the defarming method,and also various de-farming patterns have been put into practice.This paper takes the Yangou Watershed in Shaanxi Province of China as a case for studying the comprehensive benefits of transforming slope farmland to terraces.Based on the day-by-day meteorological data of the Yan'an station in 2005 and the data of terrain features,soil and land use data of the Yangou Watershed,the impact of transforming slope farmland on terraces were simulated and analyzed in aspects of yield increase and water-soil conservation under different topographic conditions with the aid of software WIN-YIELD.Furthermore,an empirical analysis was applied to study the effects of transforming slope farmland to terraces in the Yangou Watershed.The results show that:(1) The bigger the topographic gradient is,the more remarkable benefits it has in yield increase and water-soil conservation.(2) Farmland with slope below 5° could be retained,but farmland with slope above 15° should be converted to forest or grassland as soon as possible.(3) Transforming slope farmland to terraces has the same remarkable effects as the current policy of "Relieving and de-farming" in improving agricultural production conditions,safeguarding food security,raising permanent vegetation coverage rate,and preventing soil and water loss.Besides,it is more cost-effective than the policy of "Relieving and de-farming".It's strongly suggested that the policy of transforming slope farmland to terraces be carried out on the Loess Plateau without delay.

Influences of sand cover on erosion processes of loess slopes based on rainfall simulation experiments

Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China. Understanding the composition, distribution, and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion. In this study, based on laboratory rainfall simulation experiments, we analyzed rainfall-induced erosion processes on sand-covered loess slopes （SS） with different sand cover patterns （including length and thickness） and uncovered loess slopes （LS） to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion. The grain-size curves of eroded sediments were fitted using the Weibull function. Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS. The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed. The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS. Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes. The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage. Sand cover on loess slopes aggravates loess erosion, not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess, compared with the loess slopes without sand cover. The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount. Furthermore, given the same sand cover pattern, a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion. This difference explains the existence of intense erosion on slopes that are thinly covered with sand in regions where aeolian erosion and fluvial erosion interact.

Deriving the slope-mean shielded astronomical solar radiation spectrum and slope-mean possible sunshine duration spectrum over the Loess Plateau

Solar radiation is often shielded by terrain relief, especially in mountainous areas, before reaching the surface of the Earth. The objective of this paper is to study the spatial structures of the shielded astronomical solar radiation(SASR) and the possible sunshine duration(PSD) over the Loess Plateau. To this end, we chose six test areas representing different landforms over the Loess Plateau and the software package of Matlab was used as the main computing platform. In each test area, 5-m-resolution digital elevation model established from 1:10,000 scale topographic maps was used to compute the corresponding slope, SASR and PSD. Then, we defined the concepts of the slope-mean SASR spectrum and the slope-mean PSD spectrum, and proposed a method to extract them from the computed slope, SASR and PSD over rectangular analysis windows. Using this method, we found both spectrums in a year or in a season for each of the four seasons in the six test areas. Each spectrum was found only when the area of the corresponding rectangular analysis window was greater than the corresponding stable area of the spectrum. The values of the two spectrums decreased when the slope increased.Furthermore, the values of the stable areas of the spectrums in a year or in a season were positively correlated with the variable coefficients of the slope or the profile curvature. The values of the stable areas of the two spectrums in a year or in a season may represent the minimum value of test areas for corresponding future research on the spatial structures of the SASR or PSD. All the findings herein suggest that the spatial structures of the PSD and the SASR are caused by the interactions between solar radiation and terrain relief and that the method for extracting either spectrum is effective for detecting their spatial structures. This study may deepen our understanding of the spatial structure of solar radiation and help us further explore the distribution of solar energy in mountainous regions.

Optimal Scale Selection for DEM Based Slope Segmentation in the Loess Plateau

Optimal scale selection is the key step of the slope segmentation. Taking three geomorphological units in different parts of the loess as test areas and 5 m-resolution DEMs as original test date, this paper employed the changed ROC-LV (Lucian, 2010) in judging the optimal scales in the slope segmentation process. The experiment results showed that this method is effective in determining the optimal scale in the slope segmentation. The results also showed that the slope segmentation of the different geomorphological units require different optimal scales because the landform complexity is varied. The three test areas require the same scale which could distinguish the small gully because all the test areas have many gullies of the same size, however, when come to distinguish the basins, since the complexity of the three areas is different, the test areas require different scales.

The mechanism of slope instability due to rainfall-induced structural decay of earthquake-damaged loess

Natural loess slopes are characterized by a strong geological structure,which is an important factor in maintaining slope stability.The magnitude and duration of the earthquake may disturb the soil structure at different levels degrees,locally changing the arrangement between soil particles.The process of rainfall humidification weakens the cementation between soil particles,and the disturbance and humidification change the structural state of the soil,which in turn causes sliding of the slope along with the decay of soil mechanical properties.As slope instability is often the result of a series of post-earthquake ripple effects,it is of great scientific significance to study the mechanism of slope instability due to the structural decay of earthquake-damaged loess exacerbated by rainfall.In this paper,the impact of structural decay of loess on slope stability is simulated by GEOSTUDIO software under three conditions:pre-earthquake rainfall,post-earthquake rainfall and earthquake,taking the landslide in Buzi Village,Min County,Gansu Province as an example.The comparative analysis of the calculation results shows that the structural properties of the slope without earthquake disturbance are influenced by infil-tration amount.When it is fully saturated,the structural properties are similar to those of saturated soil,and the safety factor is reduced by 12.9%.In addition,the earthquake intensity and duration have different degrees of structural damage to the soil.When the structure is fully damaged,it is similar to that of remodelled soil,and the safety factor is reduced by 45.84%.Notably,the process of the earthquake and the following humidification generates the most serious damage to the loess structure,with a reduction in the safety factor of up to 56.15%.The quantitative analysis above obviously illustrates that the post-earthquake rainfall causes the most severe damage to structural loess slopes,and the resulting landslide hazard should not be underestimated.

Numerical experimental study on optimum design of anchorage system for Xiashu loess slope

In FLAC ^(3D),cable element or modified pile element can be used to build slope anchoring model.However,the difference between the two structural elements and their influence on the calculation results have not been studied in depth.In order to solve this problem,the Xiashu loess slope anchoring models based on cable element and modified pile element were constructed respectively.A variety of anchoring schemes were designed by orthogonal experiment method,and then they were brought into the model for calculation and the calculation results were analyzed by range analysis and variance analysis.The results show that the modified pile element can bear the bending moment and reflect the strain softening property of the grout.From the perspective of slope safety factor,the anchorage length and anchor bolt spacing are the main factors affecting the stability of the slope,and the anchorage angle is the secondary factor.The grout in cable element is assumed to be an elastic-perfectly plastic material,so the safety factor of the slope can be significantly increased by increasing the length of the anchor bolts.This will bring potential risks to the slope treatment project.Therefore,in the calculation of the slope anchoring model,the modified pile element is more suitable for simulating the anchor bolt.

Freeze–thaw effects on erosion process in loess slope under simulated rainfall

Seasonal freeze–thaw processes have led to severe soil erosion in the middle and high latitudes.The area affected by freeze–thaw erosion in China exceeds 13%of the national territory.So understanding the effect of freeze–thaw on erosion process is of great significance for soil and water conservation as well as for ecological engineering.In this study,we designed simulated rainfall experiments to investigate soil erosion processes under two soil conditions,unfrozen slope(UFS)and frozen slope(FS),and three rainfall intensities of 0.6,0.9 and 1.2 mm/min.The results showed that the initial runoff time of FS occurred much earlier than that of the UFS.Under the same rainfall intensity,the runoff of FS is 1.17–1.26 times that of UFS;and the sediment yield of FS is 6.48–10.49 times that of UFS.With increasing rainfall time,rills were produced on the slope.After the appearance of the rills,the sediment yield on the FS accounts for 74%–86%of the total sediment yield.Rill erosion was the main reason for the increase in soil erosion rate on FS,and the reduction in water percolation resulting from frozen layers was one of the important factors leading to the advancement of rills on slope.A linear relationship existed between the cumulative runoff and the sediment yield of UFS and FS(R2>0.97,P<0.01).The average mean weight diameter(MWD)on the slope erosion particles was as follows:UFS0.9(73.84μm)>FS0.6(72.30μm)>UFS1.2(72.23μm)>substrate(71.23μm)>FS1.2(71.06μm)>FS0.9(70.72μm).During the early stage of the rainfall,the MWD of the FS was relatively large.However,during the middle to late rainfall,the particle composition gradually approached that of the soil substrate.Under different rainfall intensities,the mean soil erodibility(MK)of the FS was 7.22 times that of the UFS.The ratio of the mean regression coefficient C2(MC2)between FS and UFS was roughly correspondent with MK.Therefore,the parameter C2 can be used to evaluate soil erodibility after the appearance of the rills.This article explored the influence mechanism of freeze–thaw effects on loess soil erosion and provided a theoretical basis for further studies on soil erosion in the loess hilly regions.

Study of Shaking Table Test on Dynamic Response Characteristics and Failure Mechanism of the Loess Slope

The natural loess that covers the ground surface has good stability due to its low water content.However,when violent earthquakes occur,the strong dynamic stress generated in the slope may induce landslide disasters with different sizes.In this paper,a large-scale shaking table model test is used to reveal the dynamic response and instability failure process of the loess slope.The test results show that different parts of the slope have different vibration characteristics and the first natural frequency in the model increases with the increase of the slope height.The response acceleration of different parts may change due to the coupling relationship between the spectral characteristics of input wave and the natural frequencies of different parts of slope,suggesting the characteristics of regional differential dynamic response.Under the condition of different dynamic response,stress state and boundary conditions of different parts of slope,a rapid microstructural damage,cumulative residual deformation evolution,and tension-shear coupling instability failure process may appear at the top of the slope with the strong dynamic response associated with the increase of dynamic loading intensity.The Sd values presented in this paper may reflect soil damage and slope instability and failure.

Inversion analysis of the shear strength parameters for a high loess slope in the limit state

It is difficult to obtain reliable shear strength parameters for the stability analysis and evaluation of high loess slopes.Hence,this paper determines slope elements and physical parameter of 79 slopes with heights of[40,120]m based on the measured loess slopes in the Ganquan and Tonghuang subregions of northern Shaanxi Province,China.In the limit state of the loess slope(stability factor Fs is 1.0),a fitting equation for the slope height and width is established.Then,the model is developed by stability analysis software-SLOPE/W,and the comprehensive shear strength parameters corresponding to different slope heights of the high slope in the study area are obtained by inversion using the Morgenstern-Price method.The results show that when the height of the slope increases,the cohesion c increases in the soil,and the internal friction angle j decreases.This change is consistent with the characteristics reflected in the composition and physical properties of the slopes,and the comprehensive strength parametric curves are very similar between the Ganquan subregion and the Tonghuang subregion.A landslide that occurred in Miaodian-zaitou of Jingyang County,Shaanxi Province,is selected to verify this inversion method,and the results show that the calculated shear strength parameters of the inversion are consistent with the measured value of the actual slope.

Effects of Shrub on Runoff and Soil Loss at Loess Slopes Under Simulated Rainfall

Improved understanding of the effect of shrub cover on soil erosion process will provide valuable information for soil and water conservation programs.Laboratory rainfall simulations were conducted to determine the effects of shrubs on runoff and soil erosion and to ascertain the relationship between the rate of soil loss and the runoff hydrodynamic characteristics.In these simulations a 20° slope was subjected to rainfall intensities of 45,87,and 127 mm/h.The average runoff rates ranged from 0.51 to 1.26 mm/min for bare soil plots and 0.15 to 0.96 mm/min for shrub plots.Average soil loss rates varied from 44.19 to 114.61 g/(min·m^2) for bare soil plots and from 5.61 to 84.58 g/(min·m^2) for shrub plots.There was a positive correlation between runoff and soil loss for the bare soil plots,and soil loss increased with increased runoff for shrub plots only when rainfall intensity is 127 mm/h.Runoff and soil erosion processes were strongly influenced by soil surface conditions because of the formation of erosion pits and rills.The unit stream power was the optimal hydrodynamic parameter to characterize the soil erosion mechanisms.The soil loss rate increased linearly with the unit stream power on both shrub and bare soil plots.Critical unit stream power values were 0.004 m/s for bare soil plots and 0.017 m/s for shrub plots.

Coupling action of rainfall and vehicle loads impact on the stability of loess slopes based on the iso-water content layer

To clarify the changes in slope stability of loess slopes under the coupling action of rainfall and vehicle loads.Experiments with different water contents under different environmental conditions were carried out indoors,and the relationship function between water content and shear strength parameters was obtained;based on Geostudio,an equivalent layered calculation model of water content-strength parameters of loess slope was established,the variation law of soil sample matrix suction with volumetric water content was measured by volumetric pressure plate tester.Finally,by using a combination of finite element analysis of saturated/unsatu-rated seepage and limit equilibrium analysis of slope stability,the SLOPE/W module in the modeling software GeoStudio is used to calculate and analyze the effects of vehicle loads,rainfall intensity,rainfall duration,and other working conditions on the stability of loess slopes,respectively.The results show that when the lane is in the middle of the slope,the vehicle load parameters have little effect on the uphill stability,but have a greater impact on the downhill;With the increase in rainfall,the change curves of the slope safety coefficient gradually overlap when the vehicle loads are four-axis,five-axis,and six-axis.This shows that when studying the change of slope safety factor under the dual influence of vehicle loads and rainfall,rainfall is the main cause of slope stability;The change rate of slope safety factor increases gradually with the increase of rainfall,and the change trends of the upper,lower and overall parts of the slope are similar.

Uncertainty of Slope Length Derived from Digital Elevation Models of the Loess Plateau, China

Although many studies have investigated slope gradient uncertainty derived from Digital Elevation Models(DEMs), the research concerning slope length uncertainty is far from mature. This discrepancy affects the availability and accuracy of soil erosion as well as hydrological modeling. This study investigates the formation and distribution of existing errors and uncertainties in slope length derivation based on 5-m resolution DEMs of the Loess Plateau in the middle of China. The slope length accuracy in three different landform areas is examined to analyse algorithm effects. The experiments indicate that the accuracy of the flat test area is lower than that of the rougher areas. The value from the specific contributing area(SCA) method is greater than the cumulative slope length(CSL), and the differences between these two methods arise from the shape of the upslope area. The variation of mean slope length derived from various DEM resolutions and landforms. The slope length accuracy decreases with increasing grid size and terrain complexity at the six test sites. A regression model is built to express the relationship of mean slope length with DEM resolution less than 85 m and terrain complexity represented by gully density. The results support the understanding of the slope length accuracy, thereby aiding in the effective evaluation of the modeling effect of surface process.

Mechanism of slope failure in loess terrains during spring thawing

Slope failure in loess terrains of Northern China during spring thawing period is closely related to the freeze-thaw cycling that surface soils inevitably experienced. Field surveys were carried out on natural and artificial slopes in thirteen surveying sites located in the Northern Shaanxi, the center of Loess Plateau, covering five characteristic topographic features including tablelands, ridges, hills, gullies and valleys. Based on the scale that is involved in freeze-thaw cycling, the induced failures can be classified into three main modes, i.e., erosion, peeling and thaw collapse, depending on both high porosity and loose cementation of loess that is easily affected. Model tests on loess slopes with gradients of 53.1°, 45.0° and 33.7° were carried out to reveal the heat transfer, water migration and deformation during slope failure. The surface morphology of slopes was photographed, with flake shaped erosion and cracks noted. For three slope models, time histories for the thermal regime exhibit three obvious cycles of freeze and thaw andthe maximum frost depth develops downwards as freeze-thaw cycling proceeds. Soil water in the unfrozen domain beneath was migrated towards the slope surface, as can be noticed from the considerable change in the unfrozen water content, almost synchronous with the variation of temperature. The displacement in both vertical and horizontal directions varies over time and three obvious cycles can be traced. The residual displacement for each cycle tends to grow and the slopes with higher gradients are more sensitive to potentially sliding during freeze-thaw cycling.

Dynamic Response of Shallow-Buried Tunnels Traversing High Loess Slopes

Considering the existence of numerous shallow-buried tunnels traversing high slopes in the loess area in western China and the fact of high seismic intensity there,we investigate the dynamic response rules of a shallow-buried loess tunnel and its slope under the action of seismic waves with different intensities.Through large-scale shaking table model tests,we successfully analyze the characteristics and process of the destabilization of tunnels and slopes,and propose valuable suggestions regarding the reinforcement parts of a tunnel for reducing seismic damage.The results show that the main seismic damage on a slope include the failure of the sliding surface between the top and foot and the stripping of the soil around the tunnel entrance,while the damage on a tunnel is mainly manifested as the seismic-induced subsidence at the portal section and the cracking deformation at the joint areas.Finally,we propose that the“staggered peak distribution”phenomenon of the maximum acceleration values at the vault and inverted arch area can be considered as a criterion indicating that the tunnel enters into the threshold of dynamic failure.

Characteristics of Soil Respiration of Terraces and Slope Farmland in Loess Hilly and Gully Regions

Soil CO_2 emissions of terraces and slope farmland in loess hilly and gully regions were measured by using Infra Red Gas Analysis(IRGA),and the diurnal variation characteristics of soil respiration rate in different slope positions of terraces and slope farmland were analyzed.The results show that the diurnal variation curves of soil respiration rate of terraces and slope farmland in loess hilly and gully regions had a single peak.The soil respiration rate of terraces reached the peak during 13:00-15:00,while the soil respiration rate of slope farmland reached the peak from 11:00 to13:00,and it was the lowest at next 07:00.The daily average of soil respiration rate in slope farmland was 0.86μmol/(m^2·s),accounting for 93.48% of that of terraces.The daily average of soil respiration rate in different slope positions of terraces and slope farmland is shown as follows:the bottom of the slope>the middle of the slope>the top of the slope.At the top of the slope,the daily averages of soil respiration rate in terraces and slope farmland were the same;at the middle and bottom of the slope,the daily average of soil respiration rate in terraces was larger than that of slope farmland.

Response of soil nutrients to terracing and environmental factors in the Loess Plateau of China

Terracing is a widely adopted agricultural practice in mountainous regions around the world that aims to conserve soil and water resources.Soil nutrients play a crucial role in determining soil quality,particularly in landscapes prone to drought.They are influenced by factors such as land-use type,slope aspect,and altitude.In this study,we sought to examine the impact of terracing on soil nutrients(soil organic content(SOC),total nitrogen(TN),nitrate-nitrogen(NO_(3)^(-)-N),ammonium nitrogen(NH_(4)^(+)-N),total phosphorus(TP),available phosphorus(AP),total potassium(TK),and available potassium(AK))and how they vary with environmental factors in the Chinese Loess Plateau.During the growing season,we collected 540 soil samples from the 0 to 100 cm soil layer across five major land-use types,different slope aspects,and varying altitudes.Additionally,a meta-analysis of literature data further corroborated the effective accumulation of soil nutrients through terracing in the Loess Plateau.Our findings are as follows:(1)Terraced fields,regardless of land-use type,showed a significant improvement in SOC and TN content.(2)Soil nutrient contents within terraced fields were predominantly higher on sunny slopes.(3)Terraces at lower altitudes are characterized by elevated SOC concentrations.(4)A meta-analysis of literature data pertaining to terracing and soil nutrients in this region confirmed the effective accumulation of soil nutri-ents through terracing.The elucidated outcomes of this study offer a profound theoretical underpinning for the accurate planning and management of terraces,the scientific utilization of land resources,and the enhancement of land productivity.