Comparison of wind erosion characteristics of different typical substrates and land use types in the arid and sandy areas——Taking Yanchi county of Ningxia as an example
Background The study of wind erosion characteristics in the arid sandy areas of Ningxia, together with the identification of soil wind erosion in different substrate types (sand dunes, shrubland, barren grassland) and land use types (available land, shrubland, barren grassland), is of great significance to the local conservation, improvement and rational use of soil and water resources, which in turn can promote the construction of a good ecological environment. Methods The experiment was conducted at a field station in Yanchi, Ningxia, and the monitoring period was from February to December. Five sub-bedding types were selected: mobile dune, semi-fixed dune, fixed dune, shrubland and barren grassland, where mobile dune, semi-fixed dune and fixed dune were planted with different cover levels of Artemisia desertorum. The plant cover average, height of vegetation and crust cover of the different sub-bedding types were investigated, and then their wind erosion thicknesses were measured by in situ brazing and wind erosion modulus calculated; the sand transport rates of the above five sub-bedding types, including creep sediment transport rate and omnidirectional sediment transport rate, were also measured by the sand collector method. The land use types of cultivated land, shrubland and barren grassland were selected to determine their wind erosion sand production thickness at different orientations (north, northeast, east, southeast, south, southwest, west, and northwest) by the wind erosion circle method. Results 1) The mean monthly wind erosion moduli for mobile dune, semi-fixed dune, fixed dune, shrubland and barren grassland were 6521.82, 5888.18, 6735.09, 6101.45 and 4076.91 t/km respectively, with fixed dune being the highest, followed by mobile dune and barren grassland being the lowest. 2) The monthly average creep sediment transport rates of mobile dune, semi-fixed dune, fixed dune, shrubland and barren grassland were 0.65, 0.71, 0.64, 0.55 and 0.68 g/(m2·min), and the monthly average omnidirectional sediment transport rates were 2.80, 0.82, 0.75, 0.68 and 0.56 g/(m2·min). The creep sediment transport rates of all sub-bedding types were similar, while the omnidirectional sediment transport rate of mobile dune was significantly higher than those of the other four sub-bedding types. Overall, the rate of sand transport was highest in spring (March to May), when wind erosion was more likely to be evident. 3) Cultivated land and barren grassland were dominated by the transport of sand and gravel, while shrubland mainly produced the accumulation of sand and gravel.Conclusions A larger area of A. desertorum can suppress wind erosion of sand dunes, and the planting of herbs is more conducive to reducing wind erosion than shrubs, so herbs such as A. desertorum can play a role in the prevention and control of wind erosion and improvement of soil and water resources in the arid and sandy areas of Ningxia.
Research on meteorological drought risk prediction model in the arid region of Northwest China
Background Drought is a temporary and recurring meteorological event that has the most serious impact on human society. The arid region of Northwest China is located in the hinterland of the Eurasian continent. Due to severe insufficient precipitation and high evaporation, the arid region of Northwest China often suffers from the impact of drought, seriously affecting local agricultural production and life, and causing serious social and economic impacts. Establishing a drought prediction model applicable to the arid region of Northwest China will effectively reduce the impact of varying degrees of drought on these areas. Methods In order to explore the neural network model suitable for meteorological drought prediction in the arid region of Northwest China, based on the precipitation data of twelve meteorological stations in the arid region of Northwest China from 1987 to 2016, the standardized precipitation index (SPI) was used as an indicator. According to the different input variables, nine groups of models were established based on the back-propagation neural network (BPNN), the extreme learning machine (ELM), and the long short-term memory network (LSTM) to predict the meteorological drought. And the stability of the model through the GLDAS dataset was verified.Results 1) The prediction accuracy of ELM is slightly improved compared to BPNN, and the training time is shorter. However, ELM and BPNN have low prediction accuracy in some regions, low reliability of the model, and poor applicability. And the two models are difficult to maintain good prediction accuracy in the case of a single input variable.2) The analysis of the results of the meteorological drought prediction model show that the prediction accuracy of LSTM is higher than that of BPNN and ELM. The coefficient of determination (R2) of the highest accuracy model M7 is 0.965, and the root mean square error(RMSE) is 0.175. The R2 in typical years are all greater than 0.8, and the RMSE is less than 0.132. 3)The analysis of the prediction results of typical years shows that LSTM performs well in the prediction of different typical years, and the prediction accuracy of dry year and extremely dry year is slightly higher than that of wet year and normal year. Meanwhile, validation of the GLDAS (global land data assimilation system) dataset showed that the best performing model M7 maintained an R2 of 0.9 or above, indicating that LSTM can ensure stable and high-precision prediction of drought conditions in the arid region of Northwest China. Conclusions Compared with BPNN and ELM, LSTM has stronger applicability and can still maintain higher prediction accuracy with fewer input variables. It shows stable predictive ability when facing different datasets. The above results indicate that the prediction model using LSTM has good applicability in the meteorological drought prediction of the arid region of Northwest China.
YANG Shifeng, LI Xuemin, ZHAO Lijun, WANG Xijin, LI Chunjiang
Ecological multifunctionality between vegetative restoration areas of transmission tower and natural grasslands in the Otindag Sandy Land
Background The Otindag Sandy Land, a critical ecological zone in northern China, faces severe desertification and land degradation. The construction of power transmission and transformation projects lead to soil erosion, vegetation destruction, and habitat loss for animals and plants, severely limiting the ability of ecosystem service function. While vegetation restoration in disturbed tower foundation areas has been implemented, the ecological multifunctionality of these restored zones compared to undisturbed natural grasslands remains unclear. In this study, to explore the impact of power transmission projects on the functionality of ecosystems, we established the restoration grassland and natural grassland plots along the L229 tower base in Duolun county, Inner Mongolia. Methods The compositions of community species were investigated in the field. The characteristics of plant leaves, aboveground and underground biomass of the community, as well as soil properties were measured in the laboratory. The species diversity and functional diversity indices of the grassland were calculated, their responses to the implementation of power transmission projects were analyzed, and the relationship between community diversity and ecosystem multifunctionality were investigated.Results The power transmission project had no significant effect on the community species diversity index, but significantly reduced the community functional diversity index. The implementation of projects mainly reduced ecosystem multifunctionality by significantly reducing soil nutrient cycling function and ecosystem quality. Species diversity and functional diversity were key factors explaining the decline in ecosystem multifunctionality, and the decrease in functional evenness index in particular had a more significant impact on multifunctionality. Conclusions The findings showed that the power transmission and transformation project in eastern Mongolia affected the soil nutrient condition, thus reducing the versatility of grassland ecosystem, providing a theoretical basis for ecological restoration measures in sandy grasslands.
ZHANG Shouhao, SUN Lei, JAMSHIDI Abdul Hakim, NIU Yong, LIU Xia, FAN Zhaofei
Status analysis of sloping cropland degradation in the black soil region of eastern Inner Mongolia
Background Black soil area in eastern Mongolia is an important commercial grain base in Inner Mongolia Autonomous Region. Soil degradation seriously affects regional food security and sustainable use of black soil. To clarify the degradation status of sloping cropland is the premise of comprehensive management and improvement of black soil. Methods Selected Moqi as the study area, sloping cropland as the research object, based on the soil measurement data, minimum data set, sequential Gaussian simulation, and mathematical statistics methods, we analyzed the spatial distribution of the degradation degree of sloping cropland in this region, the forms and the driving factors of degradation. Results 1) The minimum data set of assessment system on soil degradation degree included: Soil organic matter, A-horizon thickness, large water-stable aggregate, pH, slope, and ridge-slope angle. 2) The soil degradation index of sloping cropland in this region ranges from 0.0811-0.799 8. The slightly degraded and moderately degraded sloping cropland accounted for 83% of the total sloping cropland area. 3) The correlation between soil degradation index and A-horizon thickness was the highest (P < 0.01), were positively correlated with slope and ridge-slope angle (P < 0.05), the correlation coefficient between slope and ridge-slope angle was 0.356 (P < 0.05). Conclusions The degradation degree of sloping cropland gradually increased from northeast to southwest in study area, mainly with slightly degraded and moderately degraded sloping cropland. The loss of A-horizon layer and the reduction of cultivated area were primary characters. The interaction between slope and ridge-slope angle might be the driving factors leading to the degradation of sloping cropland. The results can provide data support for the prevention and control of sloping cropland degradation in the black soil area of eastern Inner Mongolia.
ZHAO Jixia, JIU Juanjuan, LI Yongmei, WANG Mengxue, FAN Maopan
Effects of maize-soybean intercropping on aggregate microbial biomass carbon and nitrogen in a red soil on a sloping field
Background The intercropping may obviously improve the status of soil microbes and nutrients in root areas, which in turn would promote the growth of intercropped crops. The soil microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) not only play a critical role in the formation and stability of soil aggregates, but also play an important role in the cycling and transformation of soil materials and energy. However, how the intercropping impacts on soil MBC and MBN by affecting soil aggregates is not clear yet. In order to reveal the effect of intercropping on aggregate microbial biomass carbon and nitrogen in a red soil on a sloping field, this paper examined the effects of different planting patterns on the soil community structure and the distribution characteristics of MBC/MBN in red soil sloping farmland, which may provide basis for selecting the rational planting pattern of red soil slope farmland. Methods Four treatments of bare land, mono-culture soybean, mono-culture maize and intercropping maize-soybean were set up in the runoff plot of sloping farms in the experimental farm of Yunnan Agricultural University. After three years of different planting patterns, soil samples were collected during the corn harvest period. The samples were then analyzed for soil aggregates, MBC and MBN to examine the differences under monoculture and intercropping treatments. Results 1) Compared with soybean monoculture and maize monoculture, the mean weight diameter of soil aggregates (DW) in intercropping treatment increased by 2.78% and 10.45%, the geometric mean diameter (DG) increased by 9.43%, 23.40%, and ≥ 0.25mm water stability the aggregate (R0.25) content increased by 7.35% and 15.41%, respectively, and the portion of aggregate destruction (Dp) was reduced by 9.61% and 20.66%, respectively. 2) The average values of MBC and MBC of each size aggregate in the intercropping treatment were higher than those of other treatments, and except for the size of < 0.25mm, the differences of MBC in every grade soil group were significant (P < 0.05), and the MBN in different particle size aggregates were significant (P < 0.05) except for the aggregates with particle size ≥ 5.00 mm and < 0.25 mm. The mean MBC/MBN values of the aggregates of each grain size in the intercropping treatment were all higher than monoculture treatment, with no significant differences (P > 0.05). 3) There was coefficient at soil aggregate stability index and the aggregates MBC, MBN, and the correlation was higher in the medium and large particle size aggregates than in the small particle size aggregates. Conclusions The results showed that intercropping promoted the formation and stability of red soil aggregates on sloping fields, and increased MBC and MBN, which was an ideal sloping land planting mode in the study area.
WEI Guangkuo, YAN Sheng, ZHAO Tingning, YANG Jianying, JIA Zhigang, LI Ruipeng
Effect and evaluation of different vegetation types on soil physical properties of iron tailings in Zhangxuan mining area, Hebei province
Background Iron tailings have the characteristics of loose structure and poor water storage and fertilizer retention capacity, which seriously affect the growth and development of plants. At present, the study on vegetation configuration of iron tailings restoration is relatively simple, and there is a lack of evaluation of vegetation configuration on soil physical environment after mining area restoration. Therefore, it is essential to understand and evaluate the effect of vegetation configuration on soil physical property improvement in the ecological restoration process of iron tailings. Methods We chose 14 iron tailings plots in the Zhangxuan mining area of Hebei province for vegetation investigation and soil sampling, analyzed the soil bulk density, porosity, water-holding capacity, and infiltration rate indexes. The weight was determined by the entropy weight method, and the TOPSIS method was applied to evaluate the effect of soil physical improvement under different vegetation types. Results 1) Taking bare tailings as the control, the soil physical properties of iron tailings under different vegetation types were effectively improved by revegetation on the basis of soil preparation. The soil bulk density decreased by 1.50% - 27.84%, the total porosity increased by 13.50% - 63.28%, the capillary porosity increased by 32.93% - 82.87%, the saturated water-holding capacity increased by 26.83% - 131.68 %, and the field water-holding capacity increased by 40.40% - 230.51%. There were differences in soil physical properties under different vegetation types. 2)According to the results of entropy weight-TOPSIS Model, in the early stage of vegetation restoration, the shrub mixed of Amorpha fruticosa + Lespedeza bicolor had the best improvement effect on soil physical properties, and the overall performance was shrub mixed forest > arbor-shrub mixed forest > pure shrub forest > natural restoration herbs > arbor mixed forest ≈ pure arbor forest. Conclusions It is suggested that the restoration of iron tailings should be based on engineering measures such as soil covering and local soil preparation，tree planting Pinus tabulaeformis, shrub planting A. fruticosa, L. bicolor, Hippophae rhamnoides mixed tree species and selection of Artemisia lavandulaefolia and other herbaceous plants. The results may provide theoretical basis for vegetation restoration measures and soil improvement of iron tailings.
LI Lanxiang, ZHANG Pan, WANG Wei, WANG Wei, XU Jianzhao
Analysis of the synergy between soil and water resources and regional economic development in Sanmenxia city
Background The rational use of soil and water resources is not only related to the sustainability of the ecological environment, but also directly affects the overall regional economic growth, and in turn the regional economic development will, to a certain extent, destroy the soil and water resources. As an important economic zone in Henan province, Sanmenxia city is also one of the regions with serious soil and water erosion, and it is necessary to study the relationship between water-soil resources and regional economic development in Sanmenxia city. It is necessary to understand the coordination mechanism and interaction between water and soil resources and economic development to provide theoretical support for realizing the target tasks of ecological protection and high-quality development. Methods This study took Sanmenxia city as the research object and constructed the regional water-soil-economy composite system index system. This study determined the index weights by entropy weighting method and calculating the system comprehensive development indexes. Utilizing the system coupling theory, the coupling coordination model is constructed. This study investigated the change of the coupling coordination degree between the two and the three water-soil-economic systems in Sanmenxia city from 2000 to 2020. After that, this study adopted the path analysis to explore the role of water and soil resources on regional economic development. Results The results of the comprehensive development indexes of the system showed that the level of economic development in Sanmenxia city from 2000 to 2020 shows a trend of increasing year by year. Water resources began to show a fluctuating upward trend after 2014. Land resources showed a gradual upward trend after 2004. The results of the coupling coordination degree model showed that the coupling coordination degree of land resources and economic development grows gradually after 2004, and began to reach a high degree of coordination in 2016. The degree of coupling coordination between water resources and economic development was on the verge of dislocation during the period of 2000-2012, and started to growed rapidly from 2012, reaching a highly coordinated degree in 2015. The degree of coupling coordination between water resources and soil resources reached a high degree of coordination after 2015. The coupling coordination degree of water-soil-economy showed a fluctuating upward trend from 2000 to 2014. And before 2015, the sacrifice of water and soil resources for economic development was highlighted, and the coupling coordination degree of water resources, soil resources and economic development was in a coordinated development in 2015. The results of the path analysis showed that land resources had a stronger driving effect on economic development than water resources.Conclusions The coupling coordination between water, soil resources, and economic development in Sanmenxia city is currently high, with land resources playing a key role in driving sustainable economic growth. Effective land use planning and scientific water management are essential for maintaining ecological and economic balance. Further optimization of resource use is crucial to enhance long-term economic sustainability.
Effects of slope vegetation on the stability and hydraulic properties of soil aggregates in loess hilly region
Background The loess hill is known for its fragile ecological environment and severe soil erosion. Vegetation restoration has been widely adopted as a strategy to enhance soil stability and hydraulic properties. The objective of this study is to reveal the effects of different vegetation on the stability of soil aggregates and hydraulic properties in the slop region of Loess hilly area, and to explore the appropriate vegetation patterns. Methods The wet and dry sieving method was used to study the distribution and stability of soil aggregates. The Wilcox and the ring knife head determination method were applied to study water-holding capacity (Fc) and saturated water conductivity (Ks) of the soil in the field. The relationships between the stability of soil aggregates and soil hydraulic properties with different vegetation types were investigated. Results The results showed that the destruction rate of soil aggregates under different vegetation was in the order of bare land > shrub > herb. The mean weight diameter (MWD) of soil water stability aggregates at 0–10 cm was shrub > herb > bare land. At depth of 10–30 cm, the shrub > bare land > herb. At the same depth, the Ks of shrub and herb soils were greater than those of bare soil. At 10–30 cm, the Ks of shrubs and herbs increased significantly (P < 0.05). At the same depth, Fc were all herb > shrub > bare land. Conclusions In the section of loess hilly slope, shrub and herb vegetation played crucial roles in improving soil aggregate stability and hydraulic properties. Shrub and herb increased the content of soil water-stabilized aggregates at 0–20 cm, and reduced the rate of aggregate destruction. Herb vegetation was affected by the alternation of dry and wet, so the particle size of soil aggregates decreased. With the increase of the Fc and the decrease of the MWD, shrub increased the Fc and MWD in the soil, which improved water conservation, preventing soil and water for long-term from leaching and losing.
ZHANG Jiao, GENG Yingying, WANG Tian, LI Zhanbin, LI Peng, WU Ziyi, WU Zi
Variation point analysis of sediment transport in Jialing River Basin
Background The test of sediment transport variation points serves as the cornerstone for a thorough exploration of hydrological system evolution. Jialing River is the largest tributary in the upper reaches of the Yangtze River Basin, and its water and sediment changes exert a significant on the water and sediment dynamics in the mainstream. Hence, scrutinizing and analyzing sediment transport variation points in the Jialing River offers a scientific foundation for effective water resource management within the Yangtze River basin. Methods Parameter test and non-parameter test were used for diagnosing variation points. Considering the distinct principles underlying the variation diagnosis methods of parameter and non-parameter tests, two diagnostic methods were selected in each category. The ordered clustering method and sliding t-test were selected for parametric tests, and the sliding run method and Pettitt method were selected for non-parametric tests, and the four methods were used to diagnose the variation points of the annual sediment transport at Beibei station in the Jialing River Basin from 1954 to 2021. Results 1) Without considering the prior conditions of the two kinds of diagnostic methods, the year of variation obtained by parameter test was 1984, while the year of variation obtained by non-parameter test was 1985. Autocorrelation existed in the sediment transport sequence of Beibei station, after removing the sequence autocorrelation and carrying out the non-parametric test again its diagnostic results were consistent with the parametric test diagnostic results, and the diagnostic results of the four methods are all in 1984. 2) From 1954 to 1984, the variation amplitude of annual sediment transport was stable, and the overall decrease was after 1985, and the decrease amplitude of annual sediment transport was extremely significant. The annual average sediment transport from 1954 to 1984 was 145 x 106 t, and from 1985 to 2021 was 42 x 106 t, which decreased by 71.03% compared with before the mutation point. 3) The change of sediment sources was an important reason for the decrease of sediment transport at Beibei station. The direct reason for significant decrease of sediment transport was the alternating of abundant and dry years from 1970s to 1990s under the same runoff. Since the mid-1980s, the construction of water conservancy projects in the middle and upper reaches of Jialing River Basin has been increasing continuously, which was a significant driver of sediment transport reduction. Since the late 1980s, large-scale soil and water conservation measures have reduced the sediment transport modulus of Jialing River Basin, and the sediment transport reduction effect is significant. Conclusions The variation point of annual sediment transport in Jialing River Basin from 1954 to 2021 occurres in 1984, and its variation is affected by the physical background changes such as sediment source, climate, water conservancy project construction and soil and water conservation measures.
YANG Cuihong, WANG Xu, GUO Hao, LI Yong, CHEN Tingting, HUANG Zhigang, ZHOU Xiaoqi, WU Zongmeng, YANG Jiangyi
Identification methods of sediment export load from watershed
Background The sugarcane planting area expanded to the hilly land, which intensified the soil erosion intensity in the sugarcane plantation area of Guangxi. Driven by rainfall and runoff, eroding sediment and nutrients into the water, causing serious environmental pollution. However, there are few methods to determine the eroded sediment from sugarcane fields into river. Therefore, determining the appropriate method to the eroding sediment export load from sugarcane fields, which is of great significance to control soil erosion and select the reasonable soil and water conservation measures in sugarcane growth regions. Methods In this study, a small sugarcane growing watershed in Guangxi was selected to determine the proportion of sugarcane eroding sediment contribution based on Compound Specific Stable Isotopes (CSSI). Soil loss were determined by field monitoring, 7Be tracer technique and RUSLE model under three heavy rainfall events during the early sugarcane planting period in 2020-2021. Sediment export load from sugarcane land were estimated by combinative use of field monitoring, 7Be tracer technique, RUSLE model and CSSI techniques, respectively. Results 1) Eroding sediment from sugarcane land contributed 24.5% to 42.8% in Nala watershed, which was one of the main source of sediment into the river. 2) Soil loss measured by the three methods ranged from 0.18 to 5.57 t/hm2 under single rainfall event in the order of 7Be technique > RUSLE > Monitoring. 3) Sediment export load from sugarcane was between 0.04 and 1.07 t/hm2 determined by Monitoring-CSSI method. Compared with the results of Monitoring-CSSI method, the relative error of 7Be-CSSI method was 2.74% to 1672.63%, Nash-Sutcliffe (E) coefficient was –1.47. The relative error of RUSLE-CSSI method ranged from –16.42% to 208.41%, and E value was 0.8. Conclusions Compared with the export load from sugarcane land measured by monitoring-CSSI method, the results of 7Be-CSSI method and RUSLE-CSSI method both have large error. Thus, those two methods are unsuitable for determining sediment export load from watershed.
HE Zhiteng, XIA Dong, LUO Ting, JIANG Jiayuan, ZHAO Bingqin, FU Liang, WU Qiong
Effects of land use change on soil aggregate stability and organic carbon stock in the small watershed of western Hubei karst area
Background Land-use changes significantly affect soil stability and carbon sequestration in karst regions, particularly in small watersheds, which exhibit a heightened response. This study investigates the impact of various land uses on soil aggregate stability and organic carbon distribution in the karst area of Hubei, specifically within the Xialaoxi watershed. The goal is to enhance our understanding of soil structure and the potential for carbon sequestration in these ecosystems. Methods In cypress forest (CF), vegetable farmland (VF), stone terraced field (ST), stone terraced forest (SF), and natural forest (NF), three sample plots were randomly established in each area. Within each plot, soil samples from the original surface layer (0 - 10 cm) were collected using the five-point sampling method. Mechanical stability of soil aggregates and water stability were determined using both dry and wet sieving methods. Organic carbon and active organic carbon contents of the soil in each plot were also measured. Correlation and redundancy analysis methods were employed to thoroughly analyze the impact of soil properties on soil stability. Results 1) Under different land use types, the proportion of > 2 mm mechanically stable aggregates was the highest, and it decreased as the particle size decreased. In forest land, the proportion of > 2 mm water-stable aggregates was the highest, while in farmland, it was the opposite. 2) The mechanical stability aggregates and water stability aggregates of the forest land have higher MWD and GMD than those of the cultivated land. The variation types of fractal dimension D and soil erodibility K are exactly opposite. Among them, the D and K values of the CF site are the smallest, indicating that the CF site has higher soil structure stability and stronger soil erosion resistance. 3) Soil aggregate SOC content is significantly higher in forests than in farmland, with the highest SOC content in aggregates > 0.25mm. The trend of soil aggregate LOC content is similar to that of aggregate SOC. 4) Relevance analysis and redundancy analysis results show that the SOC content of soil aggregates of various particle sizes is significantly negatively correlated with fractal dimension and soil erodibility, while it is significantly positively correlated with stability indicators MWD and GMD. The content of water-stable aggregates > 2 mm has the most significant impact on soil water stability, indicating that soil organic carbon plays a crucial role in both soil aggregate stability and soil erosion resistance. Conclusions These results indicate that the risk of soil erosion in the Xialaoxi watershed of the western Hubei karst region is relatively high, particularly in agricultural areas. The implementation of artificial afforestation measures can significantly improve soil structure and enhance the capacity for soil carbon sequestration. We should prioritize adjusting land use and implementing artificial afforestation and conservation tillage practices to mitigate the risk of soil erosion in the study area. The relevant research findings can serve as a valuable reference for the sustainable development of land use improvements and ecological protection in the small watersheds of western Hubei karst region.
YAN Jinhui, WANG Han, ZHAO Yikai, WEI Siyu, XUE Tingting, FU Yu
The surface soil anti-scouribility and aggregate loss characteristics in cultivated land of the black soil area
Background Soil erosion can cause the dispersion and breakdown of soil aggregates. One key indicator of soil erosion resistance is soil anti-scourability. In black soil regions, the surface soil of cultivated land is particularly vulnerable to the scouring effects of runoff. This runoff can further break down and disperse soil aggregates. Therefore, studying the soil’s anti-scourability, as well as the erosion characteristics of soil aggregates of different particle sizes in the surface soil of black soil cultivated land is essential. Methods To investigate the anti-scourability and aggregate loss characteristics of surface soil in cultivated land of the black soil area, the undisturbed soil (0-6 cm) was taken as the research object. The relationships between soil anti-scourability coefficient, scouring duration, scouring amount, and soil aggregate loss characteristics were explored, with 5 scouring amounts (6, 12, 18, 24, and 30 L/min) under indoor simulated runoff scouring experiments. Results 1) Overall, the total amount of soil loss gradually increased with the increase of scouring amount. The total amount of soil loss at a scouring amount of 18 L/min was 1.50 times that of 6 L/min. The soil loss decreased exponentially with decreasing scouring duration. 2) Under the conditions of scouring amounts of 6, 12, and 18 L/min, the soil anti-scourability coefficient increased as a power function with scouring duration. The soil anti-scourability coefficient was highest at a scouring amount of 18 L/min within 15 minutes, which was 2.01 and 1.38 times that at 12 and 6 L/min, respectively. 3) The loss characteristics of soil aggregates were differently affected by the scouring amount. Overall, the stability of soil aggregates gradually decreased with the increase of scouring amount, and the mass percentage of ≤ 0.25 mm aggregates gradually increased. Conversely, the mass percentage of > 2 mm aggregates gradually decreased. The fraction size of 0.5-1 mm aggregate was the main lost fraction size under different scouring amounts, accounting for 26.84%-29.66%. 4) Compared to before runoff scouring, the mass percentage of ≤ 0.25 mm aggregates under the scouring amounts of 6, 12, and 18 L/min increased by 2.49, 14.17, and 4.18 times, respectively. 5) The erosion resistance of soils gradually decreased as the scouring amount increased. The mean weight diameter of soil aggregates significantly decreased by 4.63 times than before runoff scouring under a scouring amount of 12 L/min. The fractal dimension of soil aggregates at a scouring amount of 18 L/min was 1.05 times that of 6 L/min. Conclusions The total amount of soil loss in the surface soil of cultivated land of the black soil gradually increased with the increase of scouring amount. At the same time, the soil anti-scourability became stronger and the stability of soil aggregates gradually decreased. Additionally, the erosion resistance of soil under the 3 scouring amounts was ranked as 6 > 12 > 18 L/min. The research results provide insights into the changes in the surface soil anti-scourability in cultivated land of black soil and offer references for agricultural land use.
CHEN Shijun, HUANG Yuanzhang, TAN Dingguang, WANG Jiani, QI Haimei, ZHANG Hongshan, SU Zhongyuan, WANG Yunqi
Prediction and spatial driving force analysis of soil erosion in Badong county based on CA-Markov model
Background The soil erosion in Badong county is serious, which seriously threatens the water quality safety of the Three Gorges Reservoir area. The analysis of the spatial and temporal variations as well as the factors driving soil erosion in Badong county is helpful for the government to formulate corresponding policies. Methods The spatial and temporal dynamic changes of soil erosion in Badong county in 2000, 2010, and 2020 were investigated using the RUSLE model, and the soil erosion in 2030 was predicted using the CA-Markov model. The explanatory power of six driving factors: monthly average rainfall, elevation, slope, vegetation covering, land use type, and soil type，on the spatial distribution of soil erosion was quantitatively measured using the geographical detector.Results 1) The study area was dominated by low-intensity erosion, and the three stages of sightly erosion accounted for 76.93%, 83.89% and 95.46% of the study area, respectively. From 2000 to 2020, the soil erosion intensity changed from high to sight. The area of sight erosion increased by 605.57 km2, and the other erosion areas decreased by 604.74 km2. 2) The intensity of soil erosion was predicted to keep declining through 2030. The area of sight erosion will increase by 62.78 km2 in comparison to 2020, whereas the areas of other erosion grades are going to decline. 3) Vegetation coverage, monthly average rainfall and elevation were the primary factors affecting soil erosion in Badong, and their interaction was mainly nonlinear enhancement. Conclusions Overall, there is a decreasing trend in the degree of soil erosion in Badong county, which is strongly correlated with changes to land use patterns and the implementation of water and soil conservation measures. Future efforts to minimize soil erosion and water loss should be given to the regions around the Yangtze, Qingjiang, and Shennong rivers.
