Abstract:[Objective] The variation of the observed runoff and natural runoff of the Yellow River was analyzed to explore the impact of human activities on runoff in the study area.[Methods] Based on the natural runoff and observed runoff of eight hydrological stations in the main stream of the Yellow River from 1969 to 2018, the variation of the observed natural runoff in the last 50 years was analyzed using a Mann-Kendall trend test and mutant test. In addition, the impact of human activities on runoff was considered based on the water consumption data of each region in the last 15 years.[Results] ① The observed runoff in the upper, middle, and lower reaches of the Yellow River all decreased from 1969 to 2018. The average annual reduction rates at the Lanzhou, Huayuankou, and Lijin stations were 51, 355, and 413 million m³/a, respectively. ② In the last 50 years, the greatest alteration of natural runoff and observed runoff occurred during 1986 and 1990. Combined with previous studies and important water events of the Yellow River, the runoff alteration in 1986 may have been related to the implementation of soil and water conservation measures since 1984 as well as the construction of Longyangxia Reservoir in 1986. The runoff alteration in 1990 may have been due to the surge of water consumption in the 1980s and 1990s in addition to the underlying surface water variation of the basin. ③ The difference between the natural and observed runoff gradually increased from the upper reach to the lower reach, which was generally consistent with the increased average water consumption over the past 15 years. In addition, the annual average observed runoff only accounted for 42% of natural runoff at Lijin Station. The two regions with the highest water consumption were the lower part of Huayuankou and the area between Lanzhou and Toudaoguai, reaching 1.06×10¹⁰ m³ and 1.04×10¹⁰ m³, respectively.[Conclusion] The main reason for the large difference between the natural and observed runoff in the area below Lanzhou station was the water consumption associated with human activities, especially for farmland irrigation. Therefore, it is necessary to promote the development of water-saving agriculture in the Yellow River basin and to reasonably allocate water consumption.

Abstract:[Objective] The impacts of Achnatherum splendens patches on rainfall partitioning and surface runoff were studied to provide a basis for revealing the formation of vegetation patches and the mechanism of water regulation recognition.[Methods] The deep-rooted grass of A. splendens was used in the Qinghai Lake watershed as an indicator plant to calculate the water compensation ratio of A. splendens patches in the horizontal direction by observing the redistribution of rainfall and surface runoff in the crown of A. splendens patches.[Results] ① The throughfall of the A. splendens patch accounted for 70.58% of the total rainfall and was mainly affected by rainfall, rain intensity, and duration. This was similar to most shrubs in arid ecosystems. ② The mean runoff coefficient of the A. splendens patch was 0.45%±0.33%. This was significantly lower than that of the matrix (2.08%±1.46%) and increased with rainfall. ③ The water compensation of the A. splendens patch accounted for 1.13%±1.34% of total rainfall, and it increased with rainfall and rain intensity. The highest value of the proportion of water compensation was 4.94%.[Conclusion] The A. splendens patch can be recharged by the runoff from the matrix in the ecosystem scale, which is the water regulation mechanism of drought adaptation for patchy vegetation in arid regions.

Abstract:[Objective] The effects of different mulching modes on soil water evaporation were studied during the vegetation restoration of a coal mine wasteland in an arid desert area in order to provide a scientific basis for the optimization of the ecological restoration model of abandoned land in arid desert areas, and for the improvement of vegetation restoration technology.[Methods] The influence of different mulching modes on the evaporation of soil moisture and the soil moisture content were investigated on a dump slope of a gangue field in an arid desert region. Bare land was used as a control. The tested mulching modes included straw curtain mulching, eco-mat mulching, and liquid film mulching.[Results] The moisture content of surface soil increased with a decrease in the slope position of the dump slope. The daily evaporation capacity of the soil was relatively high during the early evaporation period, but decreased gradually over time. The average daily evaporation capacity of the soil was the lowest for the straw curtain mulching mode, which differed significantly (p<0.05) from that of bare land. The cumulative evaporation capacity of the soil increased gradually at different slope positions of the dump slope under the different mulching modes. The cumulative evaporation capacity of the soil in the bare land substantially increased. The cumulative evaporation capacity of soil under the straw curtain mulching, liquid film mulching, and eco-mat mulching modes decreased by 38.4%, 24.2%, and 20.6%, respectively, compared with that of the bare land. There was a linear relationship between the cumulative evaporation capacity of the soil and time under the different mulching modes.[Conclusion] The moisture content under the straw curtain mulching mode was higher than that under the liquid film and eco-mat mulching modes. Straw curtain mulching could provide the moat reasonable mulching model for the dump slope of the gangue field.

Abstract:[Objective] The response of soil ecological environment to interference by tourism was explored in Lijiang scenic area of Guilin City in Guangxi Zhuang Autonomous Region to provide a scientific basis for the rational development and protection of tourism resources.[Methods] A field investigation and laboratory analysis were conducted to analyze the differences of soil environmental indicators in the Lijiang scenic area under different interference levels, and the impact of interference due to tourism on the soil ecological environment in the study area.[Results] The average soil firmness increased by a factor of 15.55. The brightness and chromaticity of the soil color also increased, as did the bulk density (by 33.43%). The thickness of the litter layer and soil moisture content both decreased. The contents of soil organic matter, total nitrogen, alkali-hydrolyzed nitrogen, available phosphorus, and available potassium decreased by 61.31%, 61.58%, 32.21%, 72.08%, and 36.26%, respectively.[Conclusion] The soil ecological environment of the Lijiang scenic area shifted periodically under the disturbance caused by tourism. Selected soils were degraded to different degrees, the comprehensive fertility of the soil reduced, and the soil structure deteriorated, which can be expected to affect vegetation and the landscape. Therefore, effective management measures and relevant technology should be introduced to weaken the negative effects of tourism on the ecological environment of the Lijiang scenic area.

Abstract:[Objective] The spatial distribution characteristics of soil carbon and nitrogen under different soil thicknesses in areas of land consolidation on river beaches in the middle part of Shaanxi Province were studied. The optimal soil thickness for the stability of the arable layer was also determined in order to provide a theoretical basis for the development and utilization of the resources of difficult-to-use land on river beaches.[Methods] During the period from 2015 to 2017, a field trial involving the application of a soil cover on a floodplain was carried out. A correlation analysis was performed to determine the distribution characteristics, dynamic trends, and relationship between the soil organic matter and total nitrogen under different thicknesses of the soil cover.[Results] The soil organic matter and total nitrogen content decreased with increasing soil depth under different thicknesses of soil cover. The soil depth was negatively correlated with the soil organic matter content and total nitrogen content, and the soil nutrients exhibited surface aggregation. When the soil thickness was 50—60 cm, the soil organic matter content and total nitrogen content were the highest among all soil depths, and showed a significant positive correlation (p<0.01).[Conclusion] A soil thickness of 50—60 cm is optimal for the land reclamation of floodplains and offers a good fertilizer-holding effect in the middle part of Shaanxi Province.

Abstract:[Objective] The objective of this study was to explore the heterogeneity characteristics of the niche fissure soil in the Haifeng karst basin. The purpose was to provide scientific support for the control of Haifeng natural reserve soil erosion at the study area.[Methods] Through field sampling combined with a hydrometer method and aggregate wet sieve method, the soil mechanical composition, water-stable aggregates, and organic carbon of different niche fissures in the rocky desertification sloping land were analyzed.[Results] ① The surface niche and the underground fissure had a certain spatial correlation. Based on the niche type and fissure shape, the sampling fissures were initially classified as soil funnel, stone ditch fissure, and stone pit niche. ② Soil surface funnel, stone ditch fissure, and stone pit niche were heterogeneous because of such factors as fissure shape, niche type, and presence or absence of a root system. The content of sand particles in the stone pit niche was significantly higher than that of the soil surface funnel and stone ditch fissure (p<0.05), and the content of silt grains was significantly lower than that in the stone ditch fissure. The surface organic carbon content was significantly lower than that of the stone ditch fissure (p<0.05). The sand content of the funnel was significantly higher than that of the stone ditch fissure, the silt content was significantly lower than that of the stone ditch fissure, and the surface organic carbon content was significantly lower than that of the stone ditch fissure. ③ The soil stability of the soil surface funnel, stone ditch fissure, and stone pit niche gradually deteriorated with the increase of the soil layer depth, which was convenient for soil loss. Deep root vegetation intervened in the fissure soil system to improve the soil properties and enhance the resistance to soil erosion.[Conclusion] The nature of the niche fissure soil in the Haifeng karst basin is heterogeneous. The protection and utilization of the niche should be strengthened, and deep root vegetation should be planted to improve the physical and chemical properties of the soil and enhance soil erosion resistance.

Abstract:[Objective] The soil microbial activity and its environmental influencing factors were researched to lay a foundation for the exploration of local microbial resources and the protection of a regional ecological environment.[Methods] The Ordos fieldspathic sandstone area was taken as the research object. Vegetation, soil, soil microbial quantity, enzyme activity, physicochemical properties, and vegetation-related indicators were investigated and analyzed. The interrelationship among the quantity distribution characteristics of soil microorganisms, soil ecological function, and vegetation diversity under a slope environmental gradient were also analyzed.[Results] ① Bacteria were the dominant group in the fieldspathic sandstone soil, followed by actinomycetes. Fungi were few. There were significant differences in the number of physiological groups of soil microorganisms among slope environmental gradients. ② Soil phosphatase, sucrase, urease, and catalase activities were different at different slope positions, and their contents were extremely low. There was a significant positive correlation between the fungal quantity and the acid phosphatase, as well as between the actinomycetes quantity and phosphatase and catalase. However, there was a significant negative correlation between the bacteria quantity and urease. ③ The particle sizes of soil water-stable aggregates were mostly concentrated between 0.25 and 0.5 mm. The particle size of 0.25 to 0.5 mm constituted a large proportion of soil in the shady slope, whereas the particle size of 0.106 to 0.25 mm accounted for a small proportion of soil in the shady slope. However, the sunny slope and gully bottom were the opposite of the shady slope. The soil moisture content was as follows: shady slope > gully bottom > sunny slope. The soil pH value and the contents of ammonium nitrogen, olsen-P, carbon, and calcium at the top of the sunny slope were higher than those for other slopes. The bacteria quantity was significantly negatively correlated with moisture content and calcium. The actinomycetes quantity was significantly negatively correlated with the pH value. ④ Environmental factors could account for 90% of the change of soil microbial quantity, among which the slope position and soil layer had the greatest influence (37.31%), followed by the vegetation factor (29.83%) and soil physicochemical properties (22.86%). Among the soil physicochemical properties, the aggregate particle size, moisture content, and pH value had a greater influence.[Conclusion] The slope position intensifies the differentiation of soil microorganism quantity and physiological groups, and the microorganism viability decreases as the environment deteriorates. The bottom of the ditch contains native vegetation and soil microbial resources for ecological restoration.

Abstract:[Objective] The soil physical and chemical properties under different types of cultivation for a fixed number of years were studied to provide a scientific basis for the improvement of regional ecosystem services and ecological civilization construction.[Methods] Soil samples of forest land with different vegetation restoration periods (20, 25, 35, and 50 years) were collected by a spatiotemporal method. Unfertilized farmland and natural forest were taken as the control area.[Results] ① The soil particle composition did not change significantly in the early stage of returning farmland and was similar to that of the natural forestland at 50 years, while the content of large aggregates in 20, 25, 35, and 50-year abandoned plots increased by different degrees compared with the cultivated land (17.70%, 53.23%, 52.50%, and 70.30%, respectively). ② With the increase in the number of years of vegetation restoration, the soil bulk density showed a downward trend and finally tended to natural vegetation. The soil bulk density of the 50-year plot was close to that of natural woodland. All the soil moisture characteristic curve fitted well with the Gardner model. The order of the soil water-holding capacity was as follows: natural vegetation > 25 years > 35 years > 20 years > farmland > 50 years. ③ With the increasing number of years of vegetation restoration, both soil organic matter and total nitrogen content obviously increased (p<0.05). The content in the upper layer of soil was higher than that in the subsoil, and there was a significant phenomenon of surface layer accumulation. The contents of organic matter and total nitrogen in the upper layer of soil increased by 27%, 134%, 71%, and 343%, and by 20%, 76%, 64%, and 246%, respectively, while those in subsoil increased by 7%, 88%, 53%, and 422%, and by 12%, 59%, 35%, and 201%, respectively. However, the content of total phosphorus was between 0.55 and 0.36 g/kg; thus, it was less affected by the fixed number of years of the returning farmland.[Conclusion] The grain for green project can obviously improve the soil bulk density, increase soil particle size aggregates, improve the content of organic matter and total nitrogen, and further improve soil physical and chemical properties. The physical and chemical properties of the soil abandoned in 50 years were close to that of natural forestland.

Abstract:[Objective] The characteristics of the widths, depths, width-depth ratios, profiles, and wall gradients of rills on a mollisol hillslope were analyzed to provide a scientific reference for controlling rill erosion on slope croplands in the Chinese mollisol region.[Methods] Inflow scour experiments with a 1 L/(min·m²) inflow rate were conducted over 60 min under different typical slope gradients (5° and 10°) in natural runoff plots.[Results] ① The rill profiles of the mollisol hill slope were mainly “U” shaped and the mean rill width-depth ratios ranged from 2.3 to 4.9. ② As the slope gradient increased, the undercut erosion of the rills exceeded that of the collapse erosion of the side-walls, which induced a decrease in the rill width-depth ratio and a variation in the rill profiles from a “wide and shallow type” to a “deep and narrow type”. ③ The mean rill width-depth ratios of the upper, middle, and lower hillslope positions were 2.7, 1.6, and 5.4, respectively. This reveals that the rill profile characteristics transformed from the “wide and shallow type” to the “deep and narrow type”, and then to the “wide and shallow type” from the upper hillslope to the lower hillslope. ④ The rill wall gradients of the mollisol hillslope mainly ranged from 37.7° to 85.2°, and increased with an increase in the slope gradient. The rill wall gradients of the middle hillslope were greater than those of the upper and lower hillslopes.[Conclusion] It is much more important to control rill development in the middle parts of relatively steep hillslopes than other parts; this is beneficial for alleviating rill erosion in the mollisol region of China.

Abstract:[Objective] The characteristics of wind velocity pulsation and its relation to the average wind velocity and friction wind velocity were studied to reveal the rule of the wind velocity pulsation above grassland.[Methods] A sonic anemometer was used to observe the near surface wind velocity above the grassland.[Results] The near surface wind velocity had obvious pulsating characteristics, and there was a significant positive linear correlation between the pulsation intensity and the average wind velocity. The turbulence distribution was very scattered at a low wind velocity but tended to concentrate with the increase of the average wind velocity. The turbulence intensity at the peak of its probability distribution curve was 0.23 under a wind velocity ranging from 2 to 14 m/s. There was no correlation between the friction wind velocity and the instantaneous wind velocity. The friction wind velocity was positively and linearly correlated with the average wind speed at 1 s time intervals, but the fluctuation of the calculated results was still obvious because of wind velocity pulsation. At 1 min time intervals, the influence of wind pulsation on friction velocity was approximately 10%, and the linear correlation between friction wind velocity and average wind speed was extremely significant.[Conclusion] The wind velocity pulsation has a great influence on the calculation of the friction wind velocity. Using the average wind velocity at 1 s or 1 min time intervals can effectively reduce this influence.

Abstract:[Objectives] We planted and screened suitable Forsythia plants for growth on a typical red soil in an eroded red-soil region of South China in order to provide a scientific basis for the scaled expansion and popularization of Forsythia resources.[Methods] F. suspense (P₁), F. viridissima (P₂), and F. suspensa var. sieboldii (P₃) were used as test materials in this study. Three moisture gradients (-5, -20, and -35 kPa) were designed using artificial water control experiment on three types of red soil that were developed from granite (S₁), red sandstone (S₂), and Quaternary red clay (S₃) parent materials. We then analyzed the effects of each type of red soil and moisture condition on the growth of the three Forsythia species.[Results] ① Under the three moisture gradients, the lowest irrigation time and lowest volume of irrigation water for each Forsythia species were on the S₁ soil. The irrigation volume and irrigation time of the S₃ soil were higher than those of the S₂ soil at -20 and -35 kPa, while they were the same at -5 kPa. ② Soil moisture and soil type significantly affected the growth and development of Forsythia plants on the typical red soils; however, no significant difference was observed among the plant species. The interactions between soil type and soil moisture, as well as soil type and Forsythia species had significant effects on all growth indices, and the interaction between soil moisture and Forsythia species had a significant effect on all growth indices excluding branch length. Among the three Forsythia species, under high soil moisture conditions (-5 kPa), the best growth of P₁ and P₂ occurred in the S₂ soil, while P₃ grew best in the S₃ soil. However, with a decreased moisture content (-20 and -35 kPa), all three Forsythia plants grew best in the S₃ soil.[Conclusion] In South China, it is feasible to plant the three Forsythia species under high moisture conditions in red soil that has either red sandstone or Quaternary red clay as the parent material and a soil matrix potential of ≥ -35 kPa.

Abstract:[Objective] The present situation of gully erosion in a black soil area (450 km²) was evaluated to provide the basis for the hazard assessment and scientific prevention and control of erosion gully in the black soil area of Northeast China.[Methods] We selected an undulating hilly region that was seriously affected by gully erosion as the research area for a field survey. We first located the erosion gullies on a Google satellite image and then measured their three-dimensional shape in-situ.[Results] ① Land in the study area is mainly used for farming. The results showed that cultivated land, construction land, forest land, and grassland accounted for 85%, 8%, 6%, and 1% of the total area, respectively. ② Cultivated land on slopes accounted for 86% of the total cultivated land area; 64% of the slopes in these areas had a gradient of between 0.25° and 3.0°, and 12% had a gradient of > 5°. ③ We found 1 049 erosion gullies in the research area, 55% of which were on cultivated land (577 gullies). The gully density was 1.2 km/km² and the gully erosion intensity was moderate. The proportion of the gully area was 2.89% of the total study area, which indicated an intense erosion gully. ④ The average length, width, depth, and area of the erosion gullies were 996, 13.1, 2.7 m, and 2.4 hm², respectively.[Conclusion] Gully erosion is serious in the study area of undulating hills, and mainly affects sloping cultivated land; however, the scale of erosion gullies is relatively small and the gullies can be easily managed.

Abstract:[Objective] The spatial variations of the soil moisture content and soil nutrient content in an eroded gully catchment of sloping farmland were explored to reveal the effects of black soil erosion on the grain production of sloping farmland.[Methods] The erosion gully catchment area of a typical black-soil sloping farmland region was selected as the study area. Field experiments were conducted to systematically observe the soil moisture properties and soil nutrient content during the entire growth period. The soybean and maize yields were also measured during the autumn. The spatial heterogeneity and correlation between the soil moisture content, soil nutrient content, and soybean and maize yields were determined, and the effects of gully erosion on the soil quality and crop productivity were analyzed.[Results] ① Gully-slope erosion had a significant effect on the soil moisture content of the black soil in the sloping land. The coefficient of variation of the soil moisture content at a depth of 0—20 cm in ridge and furrow soils ranged from 12.2% to 17.4% (i.e., of a medium level), and the nugget/sill was 0.2. There was a strong spatial correlation, and the nugget/sill was close to 0 during the rainy season. This indicated that the soil moisture content in the catchment area was strongly affected by the runoff migration caused by the topography and other structural factors. The spatial effective correlation distance was relatively small (55.2 m). ② The contents of soil organic matter, total nitrogen (N), total phosphorus (P), alkali-hydrolyzed N, available P, and available potassium (K) were 23.9~49.7 g/kg, 0.8~1.7 g/kg, 0.3~0.6 g/kg, 70.3~183.8 mg/kg, 27.8~78.9 mg/kg, and 71.2~202.1 mg/kg, respectively. The effective spatial correlation distance of soil organic matter content was < 100 m, and the maximum effective spatial correlation distance of the total P content was close to 500 m. ③ The soybean and maize yields varied from 1 669 to 3 223 kg/hm² and from 8 177 to 10 871 kg/hm², respectively.[Conclusion] Gully-slope erosion aggravates the spatial heterogeneity of the soil moisture and nutrient contents in the watershed, and also reduces the productivity of cultivated land.

Abstract:[Objective] A study was conducted to understand the heavy metal pollution characteristics of rainwater runoff on different underlying surfaces and the health risks of heavy metal elements in rainwater runoff for the human body. The goal was to provide reference for runoff pollution control in the construction of a sponge city in a mountainous region and provide basic data for human health protection.[Methods] The rainwater runoff of four typical underlying surfaces for a roof, road, parking lot, and square was sampled and monitored at Chongqing Jiaotong University on July 22, 2019. The even mean concentrations, electric conductivity, sodium adsorption rate, hazard quotient, and hazard index were statistically analyzed.[Results] The overall change of heavy metal elements fluctuates greatly during the square runoff process. The health risk of heavy metals in rainwater runoff on roads was the largest, and that of runoff on roofs was the smallest. The large amount of multiple metal pollutants showed a decrease in 10 min after the runoff. The decreases in Fe and Mn were the largest, the decrease in Zn was moderate, and the decrease in Cu was the lowest. As and Cr were the heavy metal pollutants with the highest health risks in rainwater runoff.[Conclusion] Heavy metal pollutants scour faster in a mountainous campus. The heavy metal elements in rainwater runoff of the underlying surfaces with a large human flow fluctuate greatly, but the health risk is low. Heavy metal elements in rainwater runoff of the underlying surfaces with heavy traffic flow have more-stable fluctuations, but they have higher health risks.

Abstract:[Objective] This study investigated the differences and dynamic relationships among multiple ecosystem services by considering the trade-off relationship of a Robinia pseudoacacia plantation with different ages and slope aspects. The findings will provide a theoretical basis for the scientific management of R. pseudoacacia plantations in the residual gully region of the Loess Plateau.[Methods] We set up 36 plots according to different stages of forest age and different slope aspects. The water conservation, soil carbon storage, soil nitrogen storage, annual productivity, and biodiversity of the selected stands were measured. Statistical parameters including the root mean square deviation were used to determine their trade-off relationship, and a redundancy analysis was performed to determine the correlation between ecosystem services and stand factors.[Results] ① The ecosystem services of the R. pseudoacacia plantation at the various ages and slope aspects were significantly different (p<0.05). As the forest age increased, so did the benefits of water conservation. Annual productivity initially increased but then decreased from young forests to middle-age forests, and was the greatest for the middle-age forests. Biodiversity increased at first and then decreased, and reached the maximum during the mature forest period, whereas the benefits of soil carbon and nitrogen storage increased gradually. Moreover, the benefits of ecosystem services on the shady slope were higher than those on the sunny slope. ② Forest age was the dominant factor causing the change in the ecosystem services trade-off relationship (p<0.05), whereas slope aspect did not have a significant effect on the trade-off of ecosystem services (p>0.05). Soil carbon retention and soil nitrogen retention were synergistic, and the trade-off of water conservation with other ecosystem services was relatively high. ③ The ecosystem services of the plantation were positively correlated with different degrees with coverage, canopy density, and litter thickness, but were negatively correlated with different degrees of slope.[Conclusion] The trade-off of ecosystem services in the R. pseudoacacia plantation was higher during the middle-age and over mature periods, which is not conducive to the overall ecosystem service benefits. Drought-tolerant shrubs or native herbs should be introduced during the middle-age forest period. Regarding the management of the over-mature period, stand density should be reasonably controlled for water conservation such that the role of other ecosystem services can be promoted to improve the overall benefits.

Abstract:[Objective] The monthly and annual changes, the frequency and duration of dust storms, fly sand, and floating dust, and the relations between these and the main climatic factors in the desert area of the middle reaches of the Heihe River basin were analyzed. The aim was to provide a basis for the early warning of sand and dust weather, and the operation and management of desert areas.[Methods] The monitoring data and meteorological data of dust-related weather during 2010—2019 from the test station of desertification control of Hongshawo desert area in the Heihe River basin were used.[Results] Dust storms and fly sand weather were more frequent and longer in spring, followed by winter. The dust-related weather in spring and winter accounted for 82.3% and 79.4% of the frequency and length of these weather phenomena, respectively, across the whole year. In the past 10 years, the overall frequency of dust storms and fly sand gradually decreased, whereas the frequency of floating dust increased year by year, as did the duration of floating dust. The monthly variation in the frequency of floating dust weather was negatively correlated with soil moisture (10 cm depth) and atmospheric humidity (p<0.01), and positively correlated with wind speed (p<0.01). The annual occurrence frequency of sandstorm weather was negatively correlated with soil temperature (5 cm depth, p<0.05) and significantly negatively correlated with atmospheric temperature (p<0.01).[Conclusion] In the past 10 years, sand and dust weather events mainly occurred in spring and winter in the desert area of the middle reaches of the Heihe River basin. The more destructive sandstorms and sand movements decreased over this period, whereas floating dust increased year by year. The main factors influencing the monthly variation in sand and dust weather frequency were shallow soil moisture, atmospheric humidity, and wind speed. The shallow soil moisture in spring affected the interannual frequency changes of sandstorms and raised dust, and the shallow soil temperature affected the interannual frequency changes of floating dust; the shallow soil temperature, humidity, and precipitation in winter affected the interannual frequency changes of sandstorms, whereas shallow layer soils and atmospheric temperature influenced the annual frequency change of fly sand.

Abstract:[Objective] The automatic monitoring system of soil-saving dam was designed to realize the real-time transmission and early warning of monitoring data, and improve the safety management ability for soil-saving dams.[Methods] Five typical dams were selected as the pilot for the design, construction, installation and trial operation of the automatic safety monitoring system of soil-saving dams. A safety prediction model for soil-saving dam was established.[Results] The system realized the automatic collection of monitoring data for rainfall, water level, seepage pressure, deformation, displacement, stress, and video of soil-saving dam, realized the prediction and early warning of potential safety hazards, and improved the safety monitoring ability of soil-saving dam.[Conclusion] The operation of the system is helpful to enhance the safety management of the warping dam system in the whole He'nan Province, and to provide a new information management mode for the soil-saving dam safety operation in the Loess Plateau in flood season.

Abstract:[Objective] Three sections of Xiaolangdi Reservoir (Nanshan, Dahengling, and Tongshuling) in the Yellow River were monitored. The present situanion of water quality and potential pollution sources of the reservoir were analyzed in order to provide help for its environmental improvement.[Methods] According to the measured water quality data of the three sections, a principal component analysis was performed to select the main evaluation factors, and the fuzzy evaluation method was used to evaluate the water quality of the reservoir.[Results] Six primary water quality factors were obtained from the principal component analysis: dissolved oxygen (DO), the 5-day biochemical oxygen demand (BOD₅), ammonia nitrogen (NH₃-N), total nitrogen (TN), total phosphorus (TP), and the potassium permanganate index (COD_Mn). The DO concentration and BOD₅ belonged to class I, with values of 3.8—12.8 and 0.9—1.7 mg/L, respectively. The NH₃-N concentration ranged from 0.03 to 0.72 mg/L, which was between classes Ⅰ and Ⅱ. The TN concentration ranged from 2 to 4.88 mg/L, which was worse than the standard of class Ⅴ. The TP concentration and COD_Mn belonged to class Ⅱ, and their values were 0.02—0.05 and 1.8—2.7 mg/L, respectively.[Conclusion] Through a principal component analysis and fuzzy comprehensive evaluation, it was found that the water quality of Xiaolangdi Reservoir basically met the legislative requirements; however, there was a risk of TN and TP pollution.

Abstract:[Objective] The suitability of the plant community configuration and landscape effect of green low impact development (LID) bio-retention facilities in buildings and residential areas was evaluated to provide a practical reference for the landscape application of bio-retention facility plant communities in Beijing City.[Methods] The bio-retention facilities of the sponge city pilot at Tongzhou District, Beijing City, were examined as the research object based on expert consultation and a field vegetation survey. The analytic hierarchy process was used to propose the factors for the evaluation of the plant landscape in bio-retention facilities, and the system was constructed from three criteria layers and 10 index layers. This model was used to evaluate the plant suitability of 45 samples of 15 biological retention measures.[Results] The biodiversity was a key indicator for the evaluation of plant landscapes in bio-retention facilities. Among the five sponge city pilots, the Simpson diversity of herbaceous plants, and the Shannon-Wiener diversity and Pielou evenness index were the higher for the Bobo pilot, with diversity indexes of 2.09, 0.86, and 0.87, respectively. The plant community landscape of the biological retention facilities in Tongzhou sponge city pilot area was at a high level. The plant landscape for five biological retention facilities was grade I, whereas four, five, and one were of grade Ⅱ, Ⅲ and Ⅳ, which accounted for 33.3%, 26.7%, 33.3% and 6.7% of the evaluation units, respectively. The plants with good evaluation effects and high suitability for practical applications included Hosta plantaginea, Lythrum salicaria, Hylotelephium erythrostictum, and Pennisetum alopecuroides. The plants with a high frequency in a seasonal landscape included Iris tectorum, Hylotelephium erythrostictum, and Symphyotrichum novi-belgii.[Conclusion] In the plant community configuration, it is necessary to pay attention to matching the LID facilities and plant configuration functions, and the development and utilization of native plants to construct the plant community. The plant hierarchy and plant morphology, and ways to increase the diversity of the plant landscape in different seasons, should also be considered.

Abstract:[Objective] The effect mechanism of packing particle sizes on the permeability of bioretention cells (BRC) and biofilm patterns was analyzed in order to optimize the particle size and corresponding filling porosity of the BRC packing layer.[Methods] By numerical simulation and experimental measurement methods, fluent software was employed to simulate and analyze the flow field pattern of BRC in the small-scale calculation zone. The streamline diagram, pressure distribution, and change diagram for six different sizes of granule particles (0.5, 1.0, 2.0, 4.0, 6.0, and 8.0 mm) were comprehensively compared. In order to verify the correctness of the simulation results, biofilms with different particle sizes were cultured and operated. The thickness of the biofilm on the particle surface was measured.[Results] When the average particle sizes were 0.5—1.0 mm, the flow field pattern was the best and a smaller eddy current with reasonable structure could be formed. This flow field was the most conducive to water infiltration and material transfer. The measured thickness of the biofilm also showed that when the particle size was 1.0 mm, the growth of the biofilm was the most uniform and the biomass was the largest.[Conclusion] The packing particle size will affect the operation effects of the BRC, and the numerical simulation can provide a reference selection of actual particle sizes in the BRC.

Abstract:[Objective] The development characteristics of transient confined water were analyzed to provide scientific reference for the treatment and prevention of accumulation landslide.[Methods] Taking the Fanshantou landslide at Songyang County, Lishui City, Zhejiang Province as an example, the mechanism of transient confined water in the loose accumulation slope was simulated and studied. By analyzing the geological background conditions, hydrogeological conditions, the deformation and failure characteristics of the landslide area, and by comparing them with the rainfall data, the different rainfall conditions and the initial water lever of the slope were simulated using the GeoStudio numerical simulation software.[Results] When there were different layers with different permeability in landslide mass, heavy rainfall or high initial water level would promote the emergence and development of transient confined water and reduce the stability of slope.[Conclusion] The generation and development of external rainfall and transient confined water have an important impact on the formation of accumulation landslide. It could reduce the stability of slope and promote the appearance of landslide.

Abstract:[Objective] To realize the unification of qualitative and quantitative evaluation, simplify the process of surface water environmental quality assessments, and reduce the public's difficulty in the cognition of water quality.[Methods] Using the surface water environmental quality index (SWQI), a statistical analysis was conducted based on 1.83×10⁵ monitoring data points from the surface water monitoring network of Shaanxi Province from 2015 to 2019.[Results] Considering SWQIs, 78.7% of them were in the range of 2.5—8.0, which had the densest points. The number of samples in each interval of the SWQI index had an approximately normal or semi-normal distribution.[Conclusion] ① We used statistical methods to obtain the SWQI qualitative evaluation thresholds Ⅰ—Ⅵ (≤ 3.5, ≤ 5.0, ≤ 6.5, ≤ 8.0, ≤ 10.0, > 10.0). ② The verification showed that it was consistent with the current surface water environment quality evaluation method at three levels of verification (section, river, and region). The SWQI can be used to evaluate the surface water environmental quality and realize the transition to the current evaluation method.

Abstract:[Objective] Considering the interactions of water, land, energy, and carbon, the impact factors and contribution of industrial carbon emissions were studied to provide suggestions to Tianjin's emission reduction decision-making bodies.[Methods] The industrial carbon emissions of Tianjin City were calculated, and a logarithmic mean divisia index was used to calculate industrial carbon emissions by introducing water and land factor to the Kaya identity.[Results] From 2004 to 2018, all industrial carbon emissions of Tianjin City showed a staged upward trend. The economic output of industrial water resources and population promoted the industrial carbon emissions of Tianjin City, and the former was the main driving factor. Water and land factor had an inhibitory effect on industrial carbon emissions. Carbon emission intensity was a promoting factor for agricultural carbon emissions, while it was an inhibitory factor for other industrial carbon emissions. Land area per capita was an inhibitory factor for agricultural carbon emissions, while it was a promoting factor for other industrial carbon emissions. The changes in the impact of land and water resources on carbon emissions in various industries agreed well with the changes in the matching degree of water and land resources. The water consumption per unit land area increased, and the promotional effect of water and land resources on carbon emission became stronger.[Conclusion] To save energy and reduce emissions, water-saving industries should be developed, and urban water and soil development and utilization should be optimized to enable water and land resources to inhibit carbon emissions.

Abstract:[Objective] The function of sloping contour earth bunds with respect to soil and water conservation and environmental enhancement on sloping farmland in a black soil area was investigated in order to provide theoretical support for the use of sloping contour earth bunds on sloping farmland.[Methods] Field experiments were carried out to observe the effects of a sloping contour earth bund on soil erosion, the soil water content, soil temperature, and soil respiration.[Results] ① The sloping contour earth bund had a remarkable effect on reducing the amount of soil erosion in the black soil area; the amount of erosion was 87.53 t/(km²·a), which was less than the allowable amount of erosion. ② Construction of the sloping contour earth bund significantly increased the soil water content (p<0.05) and the vegetation coverage ratio (p<0.01). ③ The soil respiration and soil temperature were significantly correlated in the research area, and the sloping contour earth bund clearly reduced the soil respiration rate and soil carbon loss.[Conclusion] The sloping contour earth bund exhibited remarkable effects for reducing soil erosion, improving the soil water content and temperature conditions, and reducing the soil respiration rate and soil carbon loss; hence, it is suitable for sloping farmland in the black soil area.

Abstract:[Objective] The benefits of a reed-sand barrier in a photovoltaic plant with regard to wind velocity, transported sand volume, and transported sand diameter were studied in order to provide a theoretical basis for the prevention and control of sand damage caused to the 200 MWp photovoltaic plant in Hobq Desert, Northern China.[Methods] The wind speed after placing reed-sand barrier (20, 50, 100, 200, 310 cm) and sediment transport (at a height of 0—30 cm) near the surface of the photovoltaic plant were measured. Then, the trend of indicators such as the wind speed profile, surface roughness, friction speed, average jump height, wind prevention, and sand fixation benefit were analyzed.[Results] ① The wind speed profile of the reed-sand barrier followed a logarithmic increase function and the goodness of fit (R²) of the regression was > 0.99. The aerodynamic roughness and shear velocity above the reed-sand barrier were 3.47—3.79 times and 1.39—1.54 times higher, respectively, than those above bare sand. The wind break function at a height of 20 cm was the maximum (21.72%). ② The total sediment transport of the reed-sand barrier was only 6.95% of that of the bare sand, and the sand-fixing benefit was 93.05%. More than 90% of the total sand transport flux above the bare sand was distributed within a height of 0—8 cm, whereas only 51.39% of the total sand transport flux above the reed-sand barrier was distributed at this height. Therefore, the sand flux above the reed-sand barrier tended to move towards the high layer.[Conclusion] The reed-sand barrier acted as an effective windbreak and provided sand fixation by reducing the near-surface wind speed and intercepting sand transport. Thus, the reed-sand barrier is an effective protective measure for photovoltaic tracks in sandy areas.

Abstract:[Objective] This study determines the statistical characteristics of the distribution of valleys in East Gansu Province in order to ascertain the macroscopic valley evolution in the Loess Plateau.[Methods] Field work, previous data, and remote sensing were combined to determine the distribution of loess gullies in the study region. Then, based on the classification of valleys and gullies using data processing, the expression of parameters was quantified for determining gulch development, performed statistical tests, characterized the normal distribution, and statistical tests and normal distribution properties were used to obtain the influence relationship between valleys, and cited concept parameters (e.g., safe distance), to reproduce and predict the geomorphic evolutionary process.[Results] ① There was an almost orthogonal relationship between the main trench and branch trench. The joint trend was roughly the same as that of the branch trench, and the structure controlled the development of the trench. ② The radian value data of the orthogonal deviation between the primary branch and main branch of the four groups, and the secondary branch and primary branch of the two groups all conformed to a normal distribution. ③ At a significant probability of 80%, the included angles between the main trench and first branch trench should be ≥ 69.9°, 67.6°, 59.9°, and 68.8°. The included angle between the primary and secondary branches was ≥ 55.8° and 70.5°.[Conclusion] There is a universal law in the development of valleys, whereby 70° can be regarded as the limit value of the angle of gully development.

Abstract:[Objective] Beijing-Tianjin sand control projects have been implemented for 20 years. This study intend to provide further guidance for the implementation of the second phase of the project by evaluating the effects of wind and sand fixation under the influence of the project implementation.[Methods] The vegetation coverage and wind erosion, retention rate of wind, and sand fixation service function were calculated by using a revised wind erosion equation model.[Results] The Beijing-Tianjin aeolian sand source area was dominated by grasslands, followed by forest and farmland. Since the implementation of the project, the average annual amount of soil wind erosion has been 7.87×10⁸ tons, mainly with mired and mild erosion. The amount of soil wind erosion during the implementation of the first phase of the project generally decreased year by year. Since the implementation of the second phase of the project, wind erosion hazards gradually increased, especially in subregions of desertified grasslands, where the change trend of the wind erosion modulus reached 8.96 t/(hm²·a). The average retention rate of the wind and sand fixation service function of the entire sandstorm source area reached 0.82, and the low-value areas were mainly distributed in the desertified grassland subregion (0.743) and the hilly and mountainous area of Northern Shanxi Province (0.752). Since the implementation of the second phase of the project, the retention rate in most areas increased significantly, which was consistent with the changes in vegetation coverage throughout the year as well as in winter and spring.[Conclusion] The focus of wind erosion prevention and control is on areas with a decrease in the retention rate and the desertified grassland subregions, Hunshandake sandy subregion, and Horqin sandy subregion.

Abstract:[Objective] The law of soil organic carbon (SOC) differentiation and its influencing factors in small hilly and mountainous catchment areas was studied to provide a scientific basis for the sustainable utilization of soil resources and the protection of water sources of the South-to-North water diversion project.[Methods] The spatial and temporal distribution and influencing factors of SOC in the Jianghe watershed, Shiyan City, Hubei Province were analyzed, based on the digital elevation models (DEM), Landsat 8 OLI products, and measured SOC data from 2016 to 2018. These were analyzed using a correlation analysis and principal component analysis methods.[Results] Regarding the spatial distribution, the SOC had a banded distribution and the concentration of SOC in northeast of the watershed was smaller than that in the southwest. The variability of the SOC was of a middle intensity. The SOC concentration decreased in summer and autumn, whereas it accumulated in winter. For different soil types, the SOC concentration exhibited the following order: calcaric fluvisols > haplic luvisols > dystric cambisols. For different landcover types, the SOC concentration exhibited the following order: farmland > garden plot > mixed forest > evergreen coniferous forest > deciduous shrubs. The SOC increased along with the absolute value of the earth's surface curvature and the values of ratio vegetation index (RVI) and normalized difference vegetation index (NDVI).[Conclusion] The topographic factor is the main influencing factor of SOC concentrations in the Jianghe watershed, and vegetation factors (RVI and NDVI) were the second principal components for the SOC variation. The SOC concentration can be increased by changing local small landforms, increasing forest species, and improving water and fertilizer management.

Abstract:[Objective] A soil and water loss survey was conducted. The necessary data, the maps, and other relevant data were obtained to provide comprehensive support for water and soil conservation plans at county scale.[Methods] Based on the small watershed division in Baiquan County, Qiqihar City, Heilongjiang Province, a comparative analysis was used for soil loss mapping using the indices of soil erosion severity, soil erosion intensity, and the proportions of soil and water loss areas.[Results] Mapping based on the index of the soil erosion severity of a small watershed had obvious comparative advantages. ① The map can comprehensively reflect the area, intensity, and distribution of soil and water loss in the county. These can be implemented quantitatively and accurately to the water erosion unit—the small watershed. ② Based on this map, the distribution map of key prevention and control areas of soil and water loss, soil and water loss prevention, and the control layout map and major projects distribution map can be created directly. ③ The map, combined with the soil erosion intensity map of small watersheds, can provide necessary data for typical measure designs and configurations on a small watershed scale. Those data can be implemented to every plot.[Conclusion] From the perspective of carrying out a soil and water loss survey, delimitation of key prevention and control areas of soil and water loss, and comprehensively supporting the whole process of soil and water conservation planning, the county scale soil erosion mapping based on the index of the soil erosion severity of a small watershed has better comparative advantages.

Abstract:[Objective] The distribution and sources of microplastic pollution in the Nanfei River as it flows through cities were studied in order to not only accumulate basic data for microplastic pollution prevention, but also provide a scientific basis for the control and treatment of microplastics.[Methods] The water and sediment samples from the Nanfei River, located in Hefei City, Anhui Province, were collected during March 2019, and the distribution and sources of microplastics in these samples were studied by density flotation, stereomicroscope identification, and Fourier infrared spectroscopy.[Results] Four types of microplastic particles (foams, fibers, particles, and fragments) were common in the water and sediment samples from the Nanfei River. The abundance distribution was basically similar for all types of microplastics, with all types more concentrated in the densely populated middle reaches of the river, indicating that microplastic pollution in the river was greatly affected by human activities. The particle size distribution of microplastics in the water and sediment samples showed that the abundance of microplastics decreased as the particle size increased. Fiber microplastics accounted for the largest proportion of microplastics observed, and foam microplastics accounted for the least, indicating that the microplastics were mainly derived from people's daily domestic activities and sewage treatment plant discharges. Regarding the color of the microplastics, the largest proportion of microplastics were colored or transparent, whereas black and white microplastics accounted for less. In contrast to sediments, the abundance of microplastic fragments was higher than that of microplastic particles in the water samples. The results of the Fourier infrared spectrometry showed that the particle and fiber microplastics were polyethylene, the fragments were polypropylene, and the foam microplastics were polystyrene.[Conclusion] Microplastics were widespread in river water and sediments at high levels, and were mainly derived from people's daily activities and discharges from sewage treatment plants.

Abstract:[Objective] The health status and existing problems of the mountains-rivers-forests (grasslands)-farmlands-lakes-human life communities at Chongqing area in the Three Gorges reservoir (hereinafter called Chongqing reservoir area) were studied, and the interactions between the subsystems and humans was discussed in order to provide a reference for the ecological protection, green development, ecological civilization construction, and harmonious development of the reservoir area.[Methods] Twenty one counties (districts) of Chongqing City in the Three Gorges reservoir of the Yangtze River(abbreviated as “Chongqing reservior area”) were used as examples. For these, we constructed the health evaluation index system of life community from the perspective of mountains-rivers-forests (grasslands)-farmlands-lakes-human, and evaluated the health status of the communities. These were divided into four health types with the clustering analysis method based on the relevant geographic data using 3S technology and socioeconomic statistical data.[Results] ① As a whole, the ecological system for the mountains-rivers-forests (grasslands)-farmlands-lakes-human life community in Chongqing reservoir area was classified in the sub-health group. ② The features of the “mountain” subsystem reflected the vulnerability, instability, and low carrying capacity of the ecological environment in the Chongqing reservoir area. ③ The “human” subsystem showed that the development of the county's economy and society was lagging behind and there was an obvious conflict between socioeconomic development and ecological protection. ④ The structure and function of the “forest and grassland” subsystem need upgrading and optimizing.[Conclusion] In the future, the restoration and management of the lakeside systems of mountain forests (grasslands) should be focused on the forest (grassland), field, lake, and human subsystems, along with further strengthening of the basic and applied technological research in the area, in order to achieve more scientifically integrated governance, health management, and sustainable management for the mountains-rivers-forests (grasslands)-farmlands-lakes-human community system.

Abstract:[Objective] The resilience and coordination degree of the social-ecological-economic system of five cities in the mountainous areas of northern Guangdong Province were measured to provide a theoretical basis for the sustainable development of underdeveloped areas.[Methods] From the perspective of resilience, this study constructed a theoretical framework and evaluation method of the social-ecological-economic coupling system, and established binary and ternary coordination-degree models.[Results] ① The resilience of the social-economic-ecological system generally increased; the resilience of the social and economic subsystems increased relatively slowly, whereas the resilience of the ecological subsystem decreased. ② The resilience level of the social-economic-ecological system was obvious. For example, the resilience level of the social subsystem increased, and exhibited the characteristics of being high in the surrounding areas and low in the central area. In contrast, the resilience level of the economic system exhibited a downward trend, and was high in the east and low in the west. ③ The ecological-economic system was on the verge of maladjustment, the social-ecological system was basically coordinated, and the social-economic system was primary coordinated; hence, the social-ecological-economic system was in the stage of slight maladjustment.[Conclusion] The resilience of the coupling system in Northern Guangdong Province needs to be improved, especially with respect to the ecosystem. In the future, close attention should be given to the coordination and interaction of the social-ecological-economic system in Northern Guangdong Province.

Abstract:[Objective] The coupling relationship between ecological vulnerability and economic poverty in Libo County, Guizhou Province, was studied to provide a scientific reference for the ecological environment and economic development of the region.[Methods] Libo County was studied as an example, with single administrative villages taken as the evaluation unit. The sensitivity-resilience-stress conceptual model was selected to build an evaluation index system of ecological vulnerability and construct an economic poverty evaluation index system of the village from social dimensions and economic dimensions. The two evaluation index systems were then combined to establish a coupling model of ecological vulnerability and economic poverty in Libo County, which was analyzed for the degree of coordination and the spatial distribution of the coupling of ecological vulnerability and economic poverty.[Results] ① Libo County had a relatively large proportion of lightly and moderately vulnerable administrative villages, with relatively higher ecological vulnerability in the central and southern regions and relatively lower vulnerability in the northeast. ② In Libo County, the largest proportion of administrative villages had moderate poverty, with comparatively severe poverty mainly distributed in the northeast and the south. ③ The coordination degree of the coupling of ecological vulnerability and economic poverty in Libo County was divided into six types. The proportion of coordinated and synchronous administrative villages accounted for only 10.6% of the total. The largest proportion belonged to administrative villages with a lagging environment, which were mainly in the west.[Conclusion] The coupling degree of ecological vulnerability and economic poverty in Libo County was generally low. In future developments, the relation between environmental protection and economic development must be coordinated to promote sustainable regional development.

Abstract:[Objective] The change of land use and its impacts on regional ecosystem were studied to provide a theoretical basis for the optimization of spatial layout of regional land and management of mountains, rivers, farmland, lakes, grasslands.[Methods] Based on the remote sensing data of multiple time nodes and ‘3S’ technology, this research took the South Taihang area of He'nan Province to study the law and changes in land use and ecological service value from 1990 to 2016.[Results] During the period from 2000 to 2010, the land use pattern of South Taihang area changed dramatically in comparison to the other periods. Between 2000 and 2010, dryland decreased by 211.77 km², construction land increased by 319.78 km², and the changing degree of each land-use type peaked. From 1990 to 2016, the land-use in the South Taihang area mainly changed from dryland to construction land, although the reclamation of construction land to dryland became a way to supplement farmland in the later period. A large area of unused land was developed and utilized, and the reserve resources available for development and utilization reduced continually. The total value of the ecological services decreased by 3.33 billion from 21.2 billion in 1990 to 17.8 billion in 2016. The contributions of construction land, cultivated land, forest land, grassland, and water areas to the total change of the ecological service value were -90.19%, -25.75%, -17.51%, -10.93%, and 44.46%, respectively. The ecological service functions of water temperature regulation and waste treatment were considerably damaged in the South Taihang area.[Conclusion] The changes of land use and ecosystem characteristics were obvious in the South Taihang area. To balance the relationship between construction land and the protection of cultivated land, the adjustment of the land-use structure and maintenance of ecosystem services are key aspects for optimizing the spatial layout of land and ecological restoration.

Abstract:[Objective] The boundary characteristics of the Inner Mongolia reach of the Yellow River were studied in order to provide an important theoretical basis for the construction of embankment protection in the reach.[Methods] The river boundary information of the Inner Mongolia reach of the Yellow River for the past 30 years was extracted based on the modified normalized difference water index(MNDWI) and seven phases of the Landsat satellite images taken from 1988—2018. After calculating the swing area, the maximum swing area, the swing direction, and the other indicators of the river in different periods, the spatial-temporal variations of the river were analyzed.[Results] The upper sections of the Inner Mongolia reach of the Yellow River in the Bayangaole-Sanhuhekou and the Sanhuhekou-Baotou bend(both with greater curvatures than other locations) section oscillated more seriously than the other sections, and the whole reach showed a trend of migration to the right bank. The spatial and temporal differences in the channel swing were influenced by the material composition of the riverbed, hydrodynamic conditions, water conservancy projects, soil and water conservation projects, and other human activities.[Conclusion] Embankment protection construction in the Inner Mongolia reach of the Yellow River should focus on sections of Bayangaole-Sanhuhekou, and the Sanhuhekou-Baotou bend, with their large curvature.

Abstract:[Objective] The vegetation cover in Xinjiang Uygur Autonomous Region from 2001 to 2017 and its response to the extreme climate index were analyzed in order to provide a theoretical basis for the ecological-environmental protection and sustainable development of the region.[Methods] Data of the MOD₁₃Q₁ normalized difference vegetation index (NDVI), temperature, and precipitation during the period from 2001 to 2017 were used along with the maximum synthesis method, Savitzky-Golay (SG) filtering method, and a correlation analysis to investigate the relationship between the NDVI and the extreme climate index during the growing season.[Results] ① The vegetation cover in Xinjiang was not high overall from 2001 to 2017, with a slowly improving trend since 2009, which is likely to continue in the future. ② In general, the NDVI decreased from northwest to the southeast. The Tianshan Mountains and Ili River valley were the areas with the highest values, and the NDVI in the sub-regions of Northern Xinjiang was generally higher than that of the Southern Xinjiang. ③ The NDVI was negatively correlated with the extreme temperature index in the central part of Northern Xinjiang and the southwest part of Southern Xinjiang. The diurnal temperature range (DTR) and number of cool nights (TN_10p) were the main influencing indices. The NDVI was negatively correlated with the average temperature index in desert areas, whereas it was positively correlated in some mountainous areas, which was mainly due to the variation of the annual average temperature (T_y). ④ The NDVI was positively correlated with the precipitation index. The maximum 1-day precipitation amount (RX_{1 d}), maximum 5-day precipitation amount (RX_{5 d}), and annual precipitation (TP_y) were the main contributors.[Conclusion] The vegetation coverage in Xinjiang is developing in a positive direction. The response of the NDVI to the precipitation index was higher than its response to the temperature index. The precipitation index mainly exhibited a positive influence, while the temperature index had a negative influence. Precipitation had an obvious promoting effect on the improvement of vegetation in Xinjiang.

Abstract:[Objective] The ecological evolution and driving mechanism of vegetation in Yulin City, Shaanxi Province, were studied to provide scientific data for the effect of ecological restoration projects in Yulin City.[Methods] Based on the MODIS satellite vegetation index product mod₁₃Q₁ and a pixel bisection method from 2000 to 2018, the vegetation ecosystem of Yulin City in Shaanxi Province, China, was retrieved, and the driving mechanism of the influence of climate conditions and human factors on vegetation ecological change was studied by trend analysis and correlation analysis.[Results] ① From 2000 to 2018, the vegetation ecology of Yulin City improved significantly, which was mainly manifested in the extremely significant increase trend of vegetation coverage in fluctuation, with an average annual growth rate of 1.47%. Wubu County had the largest increase among the districts and counties under its jurisdiction. ② From 2000 to 2018, the overall climate conditions became warmer and humider, and the annual precipitation showed a significant increase trend. The annual average temperature increase trend was not significant. The correlation between annual precipitation and vegetation coverage was significant, but the correlation between annual temperature and vegetation coverage was insignificant.[Conclusion] The project of returning farmland to forest and the project of the demonstration and construction of sand prevention and control have adjusted the industrial structure and reduced soil erosion. The quicksand in the sandy grassland of the Maowusu Desert has been effectively controlled, and the ecological construction benefits are significant. The ecological restoration project is the main driving force of vegetation ecological restoration in the study area.

Abstract:[Objective] The importance of soil and water conservation was evaluated as a means to provided a scientific basis for ecological protection via red line delimitation in Fujian Province.[Methods] The soil conservation modulus in Fujian Province was estimated and classified using GIS technology and the revised universal soil loss equation (RUSLE) along with data such as precipitation, soil, digital elevation, and vegetation index.[Results] The total amount of soil conservation in Fujian Province was estimated to be 2.65×10⁹ t/a, and the average soil conservation modulus was 20 789.82 t/(km²·a). The soil and water conservation functional areas in Fujian Province were classified into five types: extremely important, highly important, medium importance, relatively important, and generally important. These corresponded to areas of 3 192.54, 8 205.54, 15 547.71, 21 519.81, and 74 000.20 km², respectively, which represent 2.61%, 6.70%, 12.70%, 17.57%, and 60.42% of the total area of the province, respectively.[Conclusion] The extremely important areas, highly important areas, and areas of medium importance with respect to the need for soil and water conservation are mainly distributed in two mountain zones of the Western and Central Fujian Province and the surrounding hilly areas.

Abstract:[Objective] The change trend in land-use patterns of a port city during rapid urbanization was studied to provide a scientific basis for local land-use planning.[Methods] This research used five remote sensing images of Kuala Lumpur, Malaysia (for 2000, 2005, 2010, 2015, and 2020) as the source data. The index classification method was used to extract land-use information based on the interactive data language (IDL), and RS and GIS technology along with landscape ecology methods were used to study the change of the land-use landscape pattern of Kuala Lumpur from 2000 to 2020. Finally, the grey prediction model was used to predict land-use data for Kuala Lumpur in 2025.[Results] From 2000 to 2020, Kuala Lumpur's plantation and forest land decreased significantly, whereas construction land increased rapidly; plantations in the central part of the port and in the city circle were mainly converted into construction lands. The landscape shape of land use tended to be complex and irregular, the spatial connectivity of landscape types was reduced, and the landscape heterogeneity was enhanced. The estimated areas of construction land and plantation in Kuala Lumpur in 2025 were 1624.12 km² and 2216.99 km², respectively. Compared with previous years, the area of construction land will increase and the area of plantations will decrease.[Conclusion] In 2025, the main land-use type in Kuala Lumpur will still be plantation. From a macro perspective, with the rapid development of cities, the number of plantations will continue to decrease. Future development plans need to rationally plan land-use patterns, improve land-use efficiency, and strengthen the protection of plantations.

Abstract:[Objective] The spatiotemporal variations and regional indicator differences in water resource use in Jiangxi Province (from 2008 to 2017) were analyzed in order to provide alternative references for the efficient and effective utilization of water resources.[Methods] Based on environmental, socioeconomic, and water resource data of Jiangxi Province from 2008 to 2017, the spatiotemporal variations and regional differences in water resource use in Jiangxi Province were analyzed by using variation coefficients, Theil coefficients, a spatial classification method, and the seven color difference evaluation method of “bamboo shoots”.[Results] The development and utilization of water resources in Nanchang City from 2008 to 2017 was at a relatively high level, with an average annual water resource development and utilization rate of 46%, which was classified as an unhealthy state. The average water resource development and utilization rate of Jiangxi Province was less than 25%, which was classified as a healthy state. The distribution of industrial water and agricultural water in Jiangxi Province was quite different from 2008 to 2017, whereas the spatial distribution of domestic water and total water in 11 cities was relatively less different. From 2008 to 2017, the regional difference values of per capita water resources in Jiangxi Province was less than 380, which was in the stable area of the seven color “bamboo shoot” model. During 2008—2017, the data fluctuation decreased and the data of each city became more stable.[Conclusion] In all, there were great differences in water resource endowment in Jiangxi Province. It is necessary to analyze many water resources indicators, including population, climate, environment, terrain, and cultural difference, in order to promote sustainable development of the overall socioeconomic situation, and achieve the hamony and unity of man and water enviroment of Jiangxi Province in the future.

Abstract:[Objective] The spatiotemporal evolution of vegetation coverage and its response to climate change in the upper reaches of the Ganjiang River basin were studied to provide a scientific basis and data support for regional ecological environmental protection.[Methods] Based on MODIS normalized difference vegetation index (NDVI) data, combined with annual average temperature and annual precipitation data, the trend analysis, coefficient of variation, Hurst index, and correlation analysis were used to analyze the spatiotemporal evolution of vegetation coverage and its response to climate change in the upper reaches of the Ganjiang River basin from 2000 to 2018.[Results] ① The fractional vegetation coverage in the upper reaches of the Ganjiang River basin showed a significant increase, with a growth rate of 5.21%/10 a. Spatially, the vegetation coverage showed the distribution characteristics of being low in the middle and high in the surroundings, mainly with high vegetation coverage. The fractional vegetation coverage in the study area showed an extremely significant increase and a significant increase account for 25.59% and 39.70%, respectively, and an extremely significant decrease and a significant decrease account for 1.32% and 2.46%, respectively. Insignificant change accounts for 57.84%. ② The vegetation coverage was generally stable in the study area, with an average coefficient of variation of 14.73%. Hurst analysis showed that the antisustainability of vegetation changes in the upper reaches of the Ganjiang River basin was stronger than the sustainability, and weak antisustainability was mainly dominant. ③ The vegetation growth in the study area was generally more affected by temperature than by precipitation, but there were spatial differences.[Conclusion] The fractional vegetation coverage in the upper reaches of Ganjiang River basin changes little and will decrease slightly in the future. Temperature is the main climate factor affecting vegetation growth.

Abstract:[Objective] The temporal and spatial variation in the phenological period of vegetation in the Keriya River basin from 2000 to 2015 was explored to provide reference for the study of vegetation evolution processes in the context of climate change.[Methods] Taking MODIS MOD₀₉Q₁ products and local meteorological station data as data sources, information on the vegetation phenology was extracted by using the vegetation index dynamic threshold method and then analyzed using a spatial trend analysis. The correlation between the phenological period of vegetation and meteorological factors in different months was analyzed by a partial least squares regression method.[Results] ① The start of the growth season (SOS) in the study area was mainly between 60—180 d, the end of growth season (EOS) was between 180—322 d, and the length of the growth season (LOS) was 70—250 d. The growth period of the artificial oasis in the middle reaches began the earliest, ended the latest, and was the longest vegetation growth time. ② From 2000 to 2015, the SOS in the Keriya River basin showed advancement, with an average change rate of -1.3 d every 10 years, whereas the EOS was postponed, the LOS was extended, and the most obvious variations in trends were in the middle reaches. ③ The increased temperature and precipitation in spring advanced the SOS, and the same in autumn, delayed the EOS.[Conclusion] The vegetation phenology in the Keriya River basin has obvious distribution and change rules at different elevation gradients, and the phenology change rule of the artificial oasis in the middle reaches is far different from that of the natural vegetation, and may affect the lower reaches.

Abstract:[Objective] The differentiation effects of vegetation cover change based on elevation, aspect, slope, slope change rate, terrain niche, and relief amplitude were analyzed to provide basic information for ecological environment protection in Taiyuan City, Shanxi Province.[Methods] Based on advanced spaceborne thermal emission and reflection radiometer (ASTER) global digital elevation model (GDEM) data and remote sensing data in August 2004, August 2007, August 2011, September 2014, and September 2016, the dimidiate pixel mode was used to estimate the vegetation cover in urban districts of Taiyuan City in different periods. The differentiation and changing trend of vegetation cover in terms of elevation, aspect, slope, slope change rate, terrain niche, and relief amplitude were analyzed using the correction coefficient for topographic areas.[Results] ① The vegetation coverage was mainly medium height coverage and high coverage, which accounted for more than 65% of the total area. The overall vegetation cover increased significantly from 2004 to 2016. The areas with a significant decrease in vegetation cover were mainly distributed in Xiaodian and Jiancaoping Districts, while the vegetation cover in the west and middle east areas increased rapidly. The area of vegetation coverage decreased by 852.70 km². However, it increased by 601.62 km² during 2007—2011, showing a general trend of degradation, while the area of vegetation coverage increased by more than one half of the study area in 2004—2007, 2011—2014, and 2014—2016, and the vegetation restoration effect was better. ② In the different aspects of the slopes, there were no obvious distribution differences in the different vegetation cover change types except in the flat land area. The spatial distribution of various vegetation cover change types for different elevations, slopes, slope change rates, terrain niches, and relief amplitudes differed obviously.[Conclusion] The effect of aspect on vegetation growth change is not obvious. However, the effects of the other topographic factors (elevation, slope, slope change rate, terrain niche, and relief amplitude) on vegetation cover change are obvious.

Abstract:[Objective] The spatiotemporal evolution and function measurement of the production-living-ecological space of Taiyuan urban agglomeration region were studied to provide a scientific basis for the policy formulation of the ecological civilization construction in the research area.[Methods] Based on land-use type data and economic data of Taiyuan urban agglomeration region for 2000, 2005, 2010, and 2018, ArcGIS 10.4.1 was adopted to reclassify land-use types with respect to their functions. This was coupled with the production-living-ecological space function-measurement model and spatial heterogeneity evaluation method.[Results] ① The grain production area located in the southeast part of Taiyuan basin was the main production space of Taiyuan urban agglomeration region, which radiated and expanded from the southeast towards the surroundings. The counties with a comparatively strong function with respect to production space in 2018 included Qingxu County (2.09) and Xiaodian District (1.96). ② The living space of the research region was mainly concentrated in the urban area of Taiyuan City in the east and constantly expanded towards the south, with a general trend of decentralization and regional concentration. Counties with a relatively strong function with respect to living space in 2018 included Xiaodian District (1.89), Yingze District (1.81), and Jiancaoping District. ③ The ecological space of the research region was high in the northwest and low in the southeast. Counties with relatively greater ecological space included Jiaocheng County (4.34) among others, which were primarily located within the ecological protection area and coal mining vegetation-restoration area in the Lüliang Mountain region.[Conclusion] The spatiotemporal pattern and function measurement of the production-living-ecological space of Taiyuan urban agglomeration region are consistent with the metropolitan development pattern of core-periphery, which is also consistent with the land potential distribution.

Abstract:[Objective] The dynamic variation of vegetation and its corresponding driving mechanism (i.e., climate change) were explored to provide a basis for understanding how the regional and global dynamic variations of vegetation respond to climate change.[Methods] The moderate-resolution imaging spectroradiometer (MODIS) normalized-difference vegetation index (NDVI) time series along with digital elevation model (DEM) data and monthly precipitation/temperature data were used for a Theil-Sen Median analysis, Mann-Kendall significance test, R/S analysis, Pearson correlation analysis, and ANUSPLIN model. The spatiotemporal variation of vegetation and its future trend were analyzed, and the relation of the NDVI with precipitation and temperature was explored. Furthermore, the time-lag effects of the variation of vegetation in response to climate variables in the Beijing-Tianjin-Hebei region from 2001 to 2019 were investigated.[Results] ① During the period from 2001 to 2019, the vegetation cover increased in Beijing-Tianjin-Hebei region at a rate of 0.002 2/a. The area that is expected to degrade in the future exceeded that of the area that was expected to improve. ② Furthermore, both precipitation and temperature exerted positive effects on vegetation growth in most areas, although the response of vegetation growth to changes in precipitation was more pronounced than that of temperature. ③ The lag time for the maximum response of vegetation growth to precipitation was longer than that of temperature. More specifically, the maximum vegetation cover was associated with the precipitation of the previous 3 months and the temperature of the previous one month.[Conclusion] Due to the implementation of ecological restoration projects, the vegetation cover improved significantly in the Beijing-Tianjin-and Hebei region from 2001 to 2019, especially in the northwestern area. The relation of the NDVI with precipitation and temperature exhibited regional characteristics, and vegetation growth showed obvious lag-time effects to changes in climate variables.

Abstract:[Objective] New ideas in studying the variations of sediment discharge was explored to predict the future trend of sediment transportation level in the Yellow River, in order to provide a reference for the ecological management and hydraulic planning in this region.[Methods] Cumulative curve, moving average method and frequency analysis were used to analyze the variation characteristics and future trend of sediment discharge at the mainstream stations of the Yellow River from 1950 to 2019, based on the current status of soil and water conservation measures in the basin.[Results] The sediment discharge of the Yellow River decreased step by step from 1950 to 2019. From 1950 to 2019, the variation of cumulative measured sediment discharge at stations in the middle reaches of the Yellow River could be characterized by a “semi parabola”. According to the current status of ecological restoration and soil and water conservation in the Yellow River basin, sediment discharge of the Yellow River remained relative stable after 1997, and has reached a steady state in recent years. The annual sediment discharge at Tongguan station of the Yellow River over the next years was expected to be 1.00×10⁸ tons at 90% frequency and 5.00×10⁸ tons at 10% frequency， and the average annual sediment discharge was expected to be 1.40×10⁸ tons.[Conclusion] In order to maintain a lower and stable state of sediment discharge in the Yellow River, improving the quality and standard of soil and water conservation measures, strengthening the weakness of post soil and water conservation, and establishing a comprehensive runoff-sediment regulation system are crucial to balance the scouring and silting in the lower reaches of the Yellow River, which is the guarantee of ecological protection and high-quality development of the Yellow River basin.

Abstract:[Objective] According to a new mission given by the national strategy of ecological protection and high-quality development in the Yellow River basin (abbreviated as “Yellow River National Strategy”), the major challenges faced by soil and water conservation were analyzed in order to provide references for the high quality development of ecological construction in the Yellow River basin.[Methods] Based on the requirements of the “Yellow River National Strategy”, combined with long-term field investigations and academic research results, the development goal of soil and water conservation in the Yellow River basin in the new era was analyzed and considered.[Results] Since the founding of the People's Republic of China, through more than 70 years of management, sediments of the Yellow River has been significantly reduced, and the ecological environment of the basin been improved obviously. However, there are still some problems: ① The imbalance of spatial management, and soil erosion in some areas is still serious; ② The spatial structure of artificial vegetation system is similar, and the ecosystem is unstable; ③ The ecosystem construction lacks the optimal configuration of landscape patterns, which makes it difficult to solve the transformation of the vegetation ecosystem on the Loess Plateau from “green” to “stable” effectively; ④ The functional and mechanism problems of ecological governance are prominent and affects the sustainable development of soil and water conservation. Soil and water conservation in the new era shoulders the new mission of high-quality development, and it is also facing the change of strategic positioning and development mode, as well as the major challenges of updating traditional theoretical connotations and concepts. Therefore, it is urgent to study the key technical problems that seriously restrict the coordinated development of ecological management benefits and ecological economy, and to promote the development of soil and water conservation in the Yellow River basin in the new era.[Conclusion] The implementation of the “Yellow River National Strategy” will greatly promote the development of soil and water conservation in the Yellow River basin. Researches on ecological management of the Yellow River basin should focus on solving a series of key scientific and technological problems of ecological protection and management in high-quality development. The strategic goal of soil and water conservation should be changed from low standard and covering large area to delicate and accurate management, and to enhancing the role of soil and water conservation in promoting high-quality development of the Yellow River basin.