This study examines water yield patterns in the lower reaches of the Malian River Basin, which are typical loess plateau gully areas in eastern Gansu Province, China. These areas are crucial for regional ecosystem health and understanding the temporal and spatial characteristics and response of water yield considering climate and land-use changes. Employing the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model, we quantitatively assess the spatial and temporal patterns of water yields across four years: 1990, 2000, 2010, and 2020. Spatial heterogeneity in water yield across the lower reaches of the Malian River Basin was assessed using geographic detection techniques. Analysis revealed a fluctuating trend in total water yield from 1990 to 2020, characterized by an initial decrease, followed by an increase, and finally another decrease. Compared to 1990, total water yield in 2020 declined by 5.9×10⁷ m³ (25.43% reduction). Furthermore, spatial analysis revealed a distinct pattern in water yield distribution across the basin. Higher water yield was observed in the southern and marginal areas, whereas lower yield characterized the northern and central regions. Land-use type significantly influenced water yield capacity. Ranked from highest to lowest, the order was as follows: construction land>bare land>agricultural land>low-coverage grassland>high-coverage grassland>shrub land>forest land>open water. Moreover, a significant positive correlation was identified between water yield and precipitation, suggesting that precipitation plays a key role in water production. Conversely, a negative correlation emerged between actual evapotranspiration and altitude. Our analysis identified precipitation and actual evapotranspiration as the primary drivers of spatial variations and temporal changes in water yield, with q values ranging from 0.616 to 0.735 and 0.517 to 0.653, respectively. These findings provide valuable scientific evidence to support the development, utilization, and management of soil and water resources in the loess plateau of eastern Gansu.

This study examined the vegetation characteristics and species diversity of mixed herb communities in different years on the slope of expressway in the Loess Plateau, and explored the relationship between herb community characteristics, species diversity, and soil physical and chemical properties. The characteristics of herb communities, α species diversity, and their correlation with soil physical and chemical properties were studied using the Mantel test after 15 a, 12 a, 8 a, 4 a, and 2 a of restoration of herb communities on the highway slope of the Loess Plateau by space instead of time. In total, 13 species of 13 genera in 8 families were investigated in 15 a of slope restoration, 10 species of 10 genera in 7 families were investigated in 12 a of restoration, 5 species of 5 genera in 3 families were investigated in 8 years of restoration, 5 species of 5 genera in 3 families were investigated in 4 a of restoration, and 6 species of 6 genera in 4 families were investigated in 2 a of restoration. Patric species richness recovered in the order 15 a>12 a>8 a>2 a>4 a, the Shannon-Wiener and Simpson indices recovered in the order 15 a>12 a>2 a>8 a>4 a, and the Pielou evenness index recovered in the order 15 a>2 a>8 a>12 a>4 a. Patric species richness was significantly positively correlated with total porosity and capillary porosity, organic matter, total nitrogen, and total phosphorus (P<0.05), and the Shannon-Wiener index was significantly positively correlated with organic matter and total phosphorus (P<0.05). After spraying mixed grass species in different years on the slope, the herb communities mostly contained perennials, but there were differences in species composition and quantity of the community. The species richness, Shannon-Wiener index, and Simpson index of patric species showed an upward trend as the number of restoration years increased. Soil total porosity, capillary porosity, organic matter, total nitrogen, and total phosphorus were the key environmental factors affecting patric species richness and the Shannon-Wiener index.

For this study of the physical and chemical properties and mechanical characteristics of soil in the distribution area of Xiazangtan super large scale landslide of the upper Yellow River, plants and soil samples at different positions of the landslide were collected, and the plant growth index, soil density, water content, root content, shear strength index, and nutrient element content were measured. Spearman’s correlation analysis was used to explore the vegetation types, physical and chemical properties of soil, and the shear strength characteristics of the root-soil composite system in different positions of the landslide. The number of plant species tended to increase as the altitude decreased, and the dominant herbaceous herbs were Stipa aliena, Oxytropis ochrocephala, and Artemisia desertorum. The pH of the soil in the distribution area of the landslide was neutral to alkaline. The contents of organic matter, total nitrogen, and total phosphorus change greatly at the trailing edge of the landslide, whereas the contents of total potassium, alkali-hydrolyzed nitrogen, and four other nutrients change greatly but do not show obvious variation. The water content of soil first increases and then decreases with the decrease in altitude, while the density of soil increases as the altitude decreases, increasing by 7.05% and 5.88%, respectively. The cohesion c value and root content of the root-soil composite system first increased and then decreased as the altitude decreased. In addition, Spearman correlation analysis showed that the cohesion c value of the root-soil composite system was negatively correlated with altitude, but positively correlated with root content, organic matter, and water content. The results of this study have practical significance for guiding the prevention and control of geological disasters such as soil erosion, and shallow landslide in the upper reaches of the Yellow River, from Longyang Gorge to Jishi Gorge.

Soil moisture is indispensable for the growth and development of plants in arid zones and determines the dynamics and direction of the succession of arid plant communities. It is particularly important to investigate the dynamic characteristics of soil moisture in different landscape types at the edge of the oasis in the middle reaches of the Heihe River and to develop effective, scientific, and reasonable measures to prevent wind and fix sand to prevent desertification. This study focused on three landscape types—protected forest landscapes, desert-oasis transition zone landscapes, and desert landscapes—at the edge of the oasis in the middle reaches of the Heihe River. HYDRUS-2D model simulation, LSD analysis, and Pearson correlation analysis were used to study the characteristics of soil moisture dynamics and the influencing factors of the three landscape types. The results were as follows: (1) the RMSE of soil volumetric water content ranged from 0.002 to 0.006 cm³·cm^-3, MRE ranged from 4.22% to 5.20%, and R² ranged from 0.725 to 0.967. The simulation results showed a high degree of agreement with the measured data, and the HYDRUS-2D model can be used for simulation studies of soil moisture in this study area. (2) The soil volumetric water content of protected forest landscapes and desert-oasis transition zone landscapes showed a trend of initial increase and subsequent decrease with increasing soil depth, whereas desert landscapes showed a trend of initial decrease and subsequent increase with increasing soil depth. (3) Effective precipitation plays a decisive role in the dynamics of the soil volumetric water content, and precipitation above 9.5 mm significantly increases the soil moisture content and infiltration depth over a short period. The depth of soil moisture infiltration in all periods after precipitation in desert landscapes was higher than that in protected forest landscapes and desert-oasis transition zone landscapes. (4) The soil volumetric water content of the three landscape types was related to factors such as precipitation, evapotranspiration, bulkiness, soil granular composition, and soil water-holding properties. The soil water-holding properties were significantly correlated with factors such as precipitation and evapotranspiration (P<0.01). Of these, precipitation and clay-powder grain content were significantly positively correlated with soil volumetric water content, whereas bulk weight and sand grain content were significantly negatively correlated with soil volumetric water content. Thus, planting windbreak shrubs in the study area can increase the content of soil sticky powder particles, improve the ability of the soil to collect and utilize rainwater, and slow the process of infiltration, thus positively affecting the soil water-holding properties.

To understand the dynamic change characteristics of soil moisture in the arid region of Northwest China, the relationship between vegetation water requirement and soil moisture was explored. The perpendicular drought index (PDI) was determined on the basis of Sentinel-2 L2A and Landsat 8 OLI remote sensing data in combination with 111 soil surface measurements in the 0-10 cm layer. The PDI, modified PDI (MPDI), and vegetation-adjusted PDI (VAPDI) were used to construct a soil moisture inversion model, and four quantitative indicators—determination coefficient (R²), mean absolute error (MAE), mean relative error (MRE), and root mean square error (RMSE)—were used to assess the accuracy of the inversion model. The optimal soil moisture inversion model was selected and used in combination with the soil moisture limiting coefficient. Spatial data of the vegetation area of forest land, grassland, and cultivated land in the study area in 2019 and reference crop evapotranspiration data during the growing season at each station were collected, and a model of the ecological water requirement of vegetation was constructed to explore the spatiotemporal changes in soil moisture and vegetation water requirement in the study area. The results showed that (1) PDI, MPDI, and VAPDI determined using the two data sources showed a linear negative correlation with the measured data to varying degrees, and the coefficient of determination R² was 0.37, 0.64, and 0.59, respectively. The model evaluation indicators suggested that the soil moisture regression model of MPDI had the highest fitting coefficient of determination. The spatial distribution patterns of soil moisture obtained from the two remote sensing data were consistent. (2) The high-resolution Sentinel-2 L2A soil moisture inversion was more precise, and the overall soil moisture showed a fluctuating growth trend. The multitime average of soil moisture was 23.27%; it showed a trend of initial decrease, followed by an increase and subsequent decrease, with an overall growth rate of 74.07%. (3) The average vegetation water requirement and soil moisture content of the northern and southern mountains of Lanzhou City from April to October showed a trend of fluctuation and decline. The maximum vegetation water requirement between April and October was 3.98×10⁷ m³—observed in July—and the minimum water requirement was 0.97×10⁷ m³—observed in October. With the implementation of the environmental greening project, the northern and southern mountains of Lanzhou City have gradually formed a community structure of multispecies combination from only drought-tolerant herbs and low shrubs. In general, this study provides a reference for the rational use of soil water resources and restoration of vegetation in the two mountains of Lanzhou.

In this study, to further restore and reconstruct the historical process of land use change before and after the construction of a water storage project and better grasp and forecast the direction of land use transfer, adaptive research on land use type interpretation was performed using the support vector machine theory. The adaptive adjustment ability and evolution direction of the land use structure before and after the construction of a water storage project were analyzed by examining the dynamic change in land use. The main conclusions were as follows: (1) The overall classification accuracy of the support vector machine for land use type interpretation is as high as 91.7%, and the Kappa coefficient is 0.90, depending on the advantages of self-learning and self-adaptation. In contrast with the relatively low accuracy observed for cultivated land producers, higher classification and recognition ability was observed other land types such as water bodies and forest land. (2) The Google Earth Engine (GEE) platform was used to examine the evolution process of land use types; it was found that the implementation of the second stage of the “Three-North Shelterbelt” project (2001-2020) significantly increased the area of construction land and forest land and increased the area of forest land by nearly five times compared with the initial stage of implementation in 2000. (3) Since the construction and operation of the project, nearly two-thirds of the area of forest land and construction land have maintained their original appearance, water bodies and unused land have been affected by water conservancy and urban construction projects, and more than 65% of the area has transformed from the original appearance type to other types. The “Three-North Shelterbelt” project accelerated the increase in forest area and improvement in grassland vegetation cover, and the net increase in the transformation of low-cover grassland to medium and high-cover grassland was 48.0% and 50.2%, respectively.

This study analyzed the land use structure, dynamics, intensity, and land use conversion of the agro-pastoral ecotone of Gansu Province from 2000 to 2020 using remote sensing (RS), geographic information system (GIS), and Geodetector in combination with social and economic data. (1) From 2000 to 2020, cultivated land, forest land, and grassland were the main land use types in the agro-pastoral ecotone of Gansu Province, and the total proportion of the three was more than 95%. The difference degree of land use structure was less than 0.01, and the structure was generally stable. The overall land use change initially increased and subsequently slowed down over time. (2) The conversion of cultivated land, forest land, and grassland accounted for more than 96% of the total conversion area in the agro-pastoral ecotone of Gansu Province. Land use conversion was observed among all land use types. Converted cultivated lands were mainly converted to forest land and grassland, whereas other land use types were converted to construction land. Land use type changes were mainly concentrated in the Loess hills in central Gansu and the Loess Plateau gully region in eastern Gansu. (3) In the context of long term land use changes, Geodetector demonstrated good applicability. The driving factors for land use changes in the farming-pastoral ecotone of Gansu varied during different periods. These changes were driven by a combination of socioeconomic factors and natural geographic factors, with the former having stronger explanatory power for land use change. Interactions among these factors exhibited either two-factor enhancement or nonlinear enhancement. Two-factor interactions had stronger explanatory power for land use changes than single-factor explanations.

Numerous rodent mounds are found in areas with rodent activity in alpine grasslands in the Yellow River source zone, and soil wind erosion easily occurs owing to the dry and windy climate. The present study investigated the characteristics and trends of soil wind erosion in rodent mounds using plateau pika (Ochotona curzoniae) and plateau zokor (Eospalax baileyi) mounds in 14 test areas at different altitudes and with different vegetation coverage in the Yellow River source basin. Field-simulated wind erosion was used to determine the trends of soil loss and nutrient loss in rodent mounds in different regions under different wind speeds. The results showed a significant difference in the amount of soil loss from wind erosion between the different regions (P<0.05). When the wind speed was low, there was no significant difference in soil loss between the two types of rodent mounds. When the wind speed was increased to 12 m·s^-1, the soil loss in the plateau pika mound was greater than that in the plateau zokor mound (P<0.05). When the wind speed increased from 3 to 12 m·s^-1, the average increase in soil loss in the two types of mounds was 238.16% and 146.31%, respectively. (2) The wind erosion rate of the mound soil in each test area generally showed a decreasing trend with decreasing wind speed. Vegetation coverage was a significant factor affecting the mound soil loss at low wind speeds and was related to altitude. (3) With an increase in grassland degradation levels, the soil total nitrogen content, available nitrogen, available potassium, and organic matter content decreased significantly, whereas total phosphorus, total potassium, and available phosphorus showed an upward trend. This study shows that the difference in soil wind erosion in different regions of the Yellow River source zone is closely associated with soil moisture content, particle size, and wind speed.

Mining activities have strongly changed the characteristics of the regional hydrological cycle and have a significant impact on the chemical characteristics of groundwater. Revealing the evolutionary characteristics of the groundwater system under the influence of coal mine development can provide theoretical support for ecological environment protection and sustainable development in coal mine areas. In this paper, taking the Yimin Basin in Inner Mongolia as an example, based on hydrogeological investigation combined with the groundwater flow system theory, Piper three-line diagram, Gibbs diagram, ion proportional coefficient, mineral saturation index, and other analysis methods, the characteristics of groundwater chemical changes under the interference of coal mining activities were explored. Results indicate that the overall water environment in the study area is weakly alkaline, and the significant influence and noninfluence zones exceed the detection indexes in different degrees. Coal mining in the basin has accelerated the rate of regional hydrological cycle, causing the water quality in the significant impact zone to evolve toward desalination. The development of open-pit coal mining has opened up the previously closed groundwater system, and a series of water-rock interactions stimulated by the oxidation of sulfur-containing coal and sulfurous iron ore and acid production primarily cause the changes in the chemical characteristics of the regional groundwater. The hydrochemistry of groundwater in the basin is affected by evaporation, concentration and water-rock interactions. Along the flow direction of groundwater, the hydrochemical type in the significantly affected area changes from HCO₃-Ca·Na type to HCO₃-Ca, and the concentrations of TDS and Cl^- show a downward trend. In the nonaffected zone, the hydrochemical type changed from HCO₃-Ca·Na to Cl-Ca·Mg, and the concentrations of TDS and Cl^- showed an upward trend.

Exploring the characteristics of soil properties, fungal communities, and their driving factors in different microgeomorphic units in arid gravel desert areas is important for the study of fungal community construction mechanisms and practical guidance for targeted ecological damage restoration strategies. In this paper, the changes in soil physicochemical properties, fungal α diversity, and community composition of four microgeomorphic units (wind erosion residual hills, gravel desert Gobi, river valley, and wind sand land) in an arid gravel desert area were compared. The main factors affecting soil fungal communities in different microgeomorphological units in gravel desert areas were explored by combining plant characteristics and micrometeorological factors. Results showed that the soil in the arid gravel desert area was dominated by sandy soil, and wind sand land had the largest sandy content and the smallest clay content, which was contrary to the soil mechanical composition of the river valley. No significant difference in soil bulk density and organic matter content was found between the river valley and the gravel desert Gobi, but their soil bulk density and organic matter content were significantly higher than those of the other two microgeomorphic units. However, the soluble salt content of the river valley was 21.4%, which was significantly lower than that in other microgeomorphic units, but the soil water content was significantly higher by 39.3%. Except for the contents of available N, available K and available P in the gravel desert Gobi and wind erosion residual hills, no significant difference in the available nutrients was found in other microgeomorphological units. In addition, the α diversity of soil fungi, Shannon-Wiener index, Pieloue index, and Simpson index all showed a significant decrease in wind sand land, whereas no significant difference in other microgeomorphological units was found. However, the Chao1 index has no significant difference. At the phylum level, the dominant fungi phyla were Ascomycota and Basidiomycota in different microgeomorphic units. Ascomycota has the largest dominance in the gravel desert Gobi and wind erosion residual hills, and Basidiomycota has the largest proportion in the river valley. At the genera level, Neocamarosporium and Subramaniu in the Wind erosion residual hill, Preussia and Neocamarosporium in the gravel desert Gobi, Aspergillus and Alternaria in the river valley, and Trichophaeopsis and Neocamarosporium in the wind sand land were the dominant genera of soil fungal communities in each geomorphic unit. Soil water content, organic matter, available N, and soluble salts were the common key factors affecting the changes in soil fungal community structure in different microgeomorphic units in an arid gravel desert area. Furthermore, the soil mechanical composition in wind sand land, surface temperature and light radiation intensity of wind erosion residual hills, surface wind speed of gravel desert Gobi, and surface vegetation biomass of river valley were the differentiated ecological factors affecting soil fungal community in each geomorphic unit.

Desert vegetation is an important ecological protection barrier for oasis ecosystems in the Hexi Corridor. Studying the composition of desert vegetation and the spatial distribution of soil nutrients is important to the construction and management of desert-oasis transition zone vegetation. This study is based on several field surveys. Traditional statistical and geostatistical methods were used to investigate the composition of desert vegetation and soil nutrient characteristics in the middle section of the Hexi Corridor and the southern fringe of the Badain Jaran Desert, and their correlation with environmental factors were analyzed. Results indicated that the plant composition in the desert areas of the middle section of the Hexi Corridor and the southwestern fringe of the Badain Jaran Desert was single and had low diversity, with plant species concentrated in a few families. Typical desert plants such as Reaumuria songarica and Nitraria tangutorum were frequently found in the study area. The distribution of herbaceous plants was strongly correlated with the average annual precipitation. In Shandan County, which is located in the southern part of the study area, the biomass of herbaceous plants reached 108.01 g·m^-2. Within a certain range of annual precipitation, the biomass of shrubs increased with the increase of precipitation, with the highest value occurring in Suzhou County, near the northern slope of the Qilian Mountains, at 134.03 g·m^-2. Increasing precipitation significantly promoted the growth of herbaceous plants. The surface soil had the highest organic carbon, total nitrogen, and total phosphorus contents in the study area, with average values of 2.12, 0.25, and 0.41 g·kg^-1, respectively, and higher levels of variability than those in the soil subsurface. In the horizontal direction, the three types of soil nutrients had high variability and weak spatial autocorrelation, with maximum values of 11.22, 1.30, and 0.73 g·kg^-1 near Zhangye Oasis. Principal component analysis showed that soil properties and precipitation were the primary factors causing habitat differences in the study area. However, different environmental factors interacted with one another to jointly drive desert vegetation composition and distribution.

Five typical vegetation types (i.e., coniferous forests, meadow grasslands, alpine shrubs, alpine meadows, and sparse vegetations of limestone flat) along a vertical belt of the Qilian Mountains were selected to explore the spatial elevational patterns of soil carbon, nitrogen, and phosphorus and their stoichiometric ratios. Results showed that: (1) The contents of total carbon (C), nitrogen (N), and phosphorus (P) at the 0-40 cm depth were 15.33-83.46, 1.63-7.76, and 0.41-0.66 mg·kg^-1, respectively. Soil C and N decreased gradually with increasing altitudes, following the order coniferous forests>meadow steppes>alpine shrubs>alpine meadows>sparse vegetations of limestone flat. Soil P in alpine scrubs was significantly higher than that in alpine meadows, but the other three vegetations showed no significant difference. (2) The contents of $\mathrm{NH}_{4}^{+}-\mathrm{N}$, $\mathrm{NO}_{3}^{-}-\mathrm{N}$ and available phosphorus at the 0-40 cm depth were 11.01-14.73, 2.78-12.46, and 4.35-13.57 mg·kg^-1, respectively. Ammonium was the main inorganic nitrogen form in all vegetation types. The nitrite content decreased gradually with increasing altitude. The content of soil available phosphorus was higher in sparse vegetations of limestone flats. (3) The ratios of soil C:N, C:P, and N:P at the 0-40 cm depth were 9.52-10.11, 29.89-320.24, and 3.18-29.63, respectively. Soil C:N decreased with elevation. Soil C:P and N:P were significantly lower in the soil of sparse vegetations of the limestone flat than in other vegetations, indicating that carbon and nitrogen were the limiting nutrients in the limestone flat. By contrast, the limestone flat was in a phosphorus-rich state. Elevational variations in soil C, N, and P contents and their stoichiometric ratios reflect the joint control of multiple environmental factors, thereby affecting the biochemical processes of soil C, N, and P.

Root biomass is an important part of the soil ecosystem, however, due to the limitations of measurement techniques and methods, it is impossible to rapidly assess it. The ground penetrating radar (GPR) is an efficient and nondestructive geophysical tool through which root information can be obtained without damaging the soil environment. However, accuracy during the detection and identification of underground roots by GPR is significantly affected by many factors such as soil water content, root roughness, length, and extension direction. In particular, soil water content has an obvious effect on root detection. In this study, in situ root embedding detection experiments were carried out to investigate the influence of soil water content on root detection via GPR. Combined with the changes in wave velocity, amplitude, and the root reflection coefficient of the GPR, the root point identification rate and root point distance root point root mean square error were analyzed under different average soil water content. The results showed that (1) the wave velocity and amplitude of the GPR were important parameters to determine variations in soil water conten during root detection; (2) the GPR’s velocity decreased and the radar amplitude flattened with the increasing soil water content; (3) as the root diameter increased at different soil depths, the GPR’s wave velocity also increased and the GPR’s amplitude tended to be drastic changes; (4) the root point recognition rate and soil water content were negatively correlated (P<0.05), and the best recognition effect was achieved when the soil water content was 15%-25%. These results are great significance for quantifying the effect of soil moisture content on the root detection accuracy of the GPR. In addition, it provide a reference for using this tool for root detection and are particularly important for the estimation of plant root biomass.

The formation and development of glaciers depend on a combination of topographic conditions and climatic factors, such as precipitation and temperature. However, the mechanisms underlying glacier distribution and variation remain uncertain. Our study aims to explore the relationship between glacier distribution patterns and topographical factors and uncover the driving forces behind them. To accomplish this, we utilized the Randolph Glacier Inventory version 6 and NASADEM for our analysis. Initially, we derived four key topographical factors based on NASADEM: relief degree of land surface (RDLS), altitude, slope, and aspect. Because the calculation of RDLS has scale dependence, the key is to determine the optimal analysis window using the average change-point analysis approach. The identified optimal analysis window size for RDLS evaluation in the study area was a rectangular neighborhood of 36 × 36 pixels, corresponding to an area of approximately 1.17 km². Subsequently, we examined glacier distribution patterns across various terrains in the Tibetan Plateau using the distribution index. This index elucidates the disparities between actual and standard glacier distributions across various mountain chains, excluding area disturbances. Finally, we employed the geodetector method to quantitatively assess the spatial interplay between glacier distribution patterns and topographical elements. This innovative statistical approach identifies spatially stratified heterogeneity, pinpoints explanatory factors, and evaluates interactive relationships between variables. The results show that: (1) Glacier distribution in the Tibetan Plateau shows strong selectivity for RDLS and altitude, with wide suitability for aspect and slope. The predominant distribution involves large RDLS and high altitudes. (2) Topography significantly influences glacier development, with varied effects of topographic factors on the spatial distribution of glaciers. Altitude and RDLS emerged as dominant factors controlling the distribution of glaciers, followed by slope and aspect. The interactive detection revealed that the combined effect of altitude and RDLS had a dominant impact on spatially stratified glacier heterogeneity. (3) Among altitude and RDLS gradients, the Himalayas Mountains had the most extensive glacier distribution, followed by the Karakoram Mountains. The other ten mountain ranges demonstrated diverse glacier distributions, though they mostly adhered to a normal pattern. This study will serve as a theoretical reference and provide data support for regional hydrology research. It offers vital guidance for appropriate water resource management in arid lands.

This study focuses on the Crescent Spring Area at the western end of the Hexi Corridor. Through sample collection experiments, the research systematically analyzed hydrochemical characteristics, environmental isotopes, and hydrogeochemical processes within the study area. The results indicate that mountain water, originating from atmospheric rainfall and glacial meltwater, is the primary source replenishing the diving pool in the area, with a close causal link between the two. Additionally, the local area is affected by the fault structure or cross-flow and receives lateral replenishment from the deep underground runoff in front of the Qilian Mountains. The evaporation effect of groundwater in the Danghe irrigation area is weak, primarily discharging through artificial mining. Other groundwater burial areas mainly discharge through evaporation and transpiration. The chemical composition of groundwater is influenced by the karst filtration involving carbonate and silicate. Key factors controlling groundwater salinity include the dissolution of rock salt, gypsum, and partite rocks, as well as the precipitation of calcite and dolomite, along with evaporation. Various degrees of mixing occur during the water cycle in the basin. Overall, these research findings provide a scientific basis for the ecological protection and restoration of Crescent Lake.

This study examines the hydrochemical characteristics and controlling factors of surface water in the Yigong Lake Basin, southeast Tibet, through the collection of 26 groups of surface water samples. Linear trend diagrams, Gibbs diagrams, and Piper diagrams of the main ions in the water sample points were drawn. Moreover, correlation analysis, linear trend analysis, mathematical statistics, and ion ratio were used to analyze the surface water’s main ion characteristics and controlling factors in the study area, unveiling its material sources. The results show that the predominant cations in the Yigong Lake Basin surface area were Ca²⁺ and Mg²⁺, while K⁺ and Na⁺ levels were relatively low. The hierarchy of cation content was Ca²⁺ > Mg²⁺ > Na⁺ > K⁺. Among anions, \mathrm{H} \mathrm{C} {\mathrm{O}}_3^{-} , \mathrm{S} {\mathrm{O}}_4^{2-} ,and Cl^- dominated, with relatively low levels of \mathrm{N} {\mathrm{O}}_3^{-} and F^-. The hierarchy of anion content was \mathrm{H} \mathrm{C} {\mathrm{O}}_3^{-}> \mathrm{S} {\mathrm{O}}_4^{2-}>Cl^- > \mathrm{N} {\mathrm{O}}_3^{-}>F^-, and the concentration value of H₂SiO₃ maintained a steady fluctuation around 6.9 mg·L^-1. The pH value consistently ranged between 7.84 and 8.37, indicating weak alkalinity. The three main ions in the surface water of the Yigong Lake Basin were Ca²⁺, Mg²⁺, and \mathrm{H} \mathrm{C} {\mathrm{O}}_3^{-}, and the hydrochemical types were mainly HCO₃-Ca·Mg or HCO₃-Ca. Rock leaching was the primary controlling factor, with minimal influence from cation-alternating adsorption, evaporation, or human activities on water concentration.

The Guanzhong region serves as the main agricultural production base in Shaanxi Province. However, frequent droughts severely impede socioeconomic development in the area. Soil moisture, a vital drought indicator, can offer valuable insights into understanding drought laws and formulating policies to address them by studying the response of soil moisture to climate factors. Within the Guanzhong region, long-term MODIS-NDVI and MODIS-LST series data from 2001 to 2020 were used to establish the characteristic spatial distribution of surface soil moisture and dryness (TVDI). The linear trend method, correlation analysis, sensitivity analysis, and other mathematical statistical methods were used to scrutinize the spatial distribution patterns of soil moisture and dryness in response to climate conditions. Key results are as follows: (1) TVDI can accurately reflect soil moisture status in the Guanzhong region, revealing a trend of both soil drying and wetting over the past two decades, with spring being the driest, followed by winter. (2) There is significant spatial heterogeneity in soil moisture distribution and dryness, with an overall trend of increasing drought from the southwest to the northeast. (3) Soil moisture exhibits correlations with precipitation and temperature: it is positively correlated with precipitation (as precipitation increases, soil moisture increases) and negatively correlated with temperature (as temperature increases, soil moisture decreases). (4) Precipitation has a high sensitivity to soil moisture and dryness, while temperature significantly impacts the degree of changes in soil moisture and dryness. Precipitation determines the direction in which soil moisture values increase or decrease, whereas temperature determines the degree of increase or decrease. Soil dryness and wetness act as comprehensive indicators, influenced by both precipitation and temperature. Precipitation predominantly determines the trend of value increase or decrease, while temperature determines the magnitude of the increase or decrease. Hence, when studying the impacts of temperature and precipitation, precipitation emerges as the main factor controlling soil moisture and dryness trends, while temperature regulates the extent of these changes.

To objectively reflect the surface water quality status, a combination of the Analytic Hierarchy Process Entropy Weight Method and the weighted average comprehensive evaluation principle were used to improve the fuzzy comprehensive evaluation method. The method was compared with the single factor evaluation, Nemero index, and traditional undefined extensive evaluation methods to evaluate the surface water environmental quality in the Chengde area in 2021. The results showed a significant spatiotemporal difference in the surface water quality. Except for some sections with poor water quality from July to September, the water quality in other sections was in Classes I-III; The main factors affecting surface water quality in the Chengde area were COD_Mn and TP; The single factor evaluation and the Nemero index methods could not reflect the overall water quality. Compared to the traditional fuzzy comprehensive evaluation method, the improved fuzzy comprehensive evaluation method considers the interaction between various pollution factors and weakened the impact of individual water quality indicators on the evaluation results. It can also rank the category of water quality, making it more suitable for evaluating the environmental quality of surface water in the Chengde area.

Water is the most critical limiting factor for plant survival, and the study of water utilization in desert plants has become the key to ecological protection and vegetation restoration programs. This study focused on three typical sand-fixing plants: Pinus sylvestris, Populus simonii, and Hippophae rhamnoides, in the sandy land on the east shore of Qinghai Lake, as the research material. The potential water source (varying levels of soil water) and the primary water sources for plants under the influence of micro-topography were analyzed by hydrogen and oxygen stable isotope technology (δ¹⁸O and δD) and the IsoSource isotope mixing model. The results show that: (1) the soil water content demonstrated micro-topography-based differences, which manifested as the soil water content on the windward slope being higher than that on the top of the sand dunes and the middle of the windward slope and the soil water content was at its highest in September. (2) the δ¹⁸O value of the xylem water varied in the tree species under different micro-topographic conditions. The δ¹⁸O values of P. sylvestris in the lowland of the windward slope were the lowest, while those of H. rhamnoides and P. simonii were the least in the middle of the windward slope. (3) marked seasonal variations were observed in the primary sources of water for different plants. In June, P. sylvestris and H. rhamnoides used deep soil water as the major source under varied micro-topographic conditions, while P. simonii mainly used deep soil water at the top of sand dunes. The soil water of the middle-layer was utilized more in the middle and lowlands of the windward slope. Still, with the increase of precipitation, various tree species turned to mainly using the shallow and middle soil water in September. In summary, the water use patterns of sand-fixing plants in the alpine sandy land were influenced by micro-topographic conditions, and varying species showed different degrees of response to precipitation.

This study aimed to investigate the apparent soil nitrogen balance and tuber yield of Cyperus esculentus in sandy farmland under different levels of nitrogen application and provide a theoretical basis for increasing the yield of Cyperus esculentus in sandy farmland. Four nitrogen fertilizer treatments, 0 kg·hm^-2 (N0), 75 kg·hm^-2 (N1), 150 kg·hm^-2 (N2), and 225 kg·hm^-2 (N3), were applied to Cyperus esculentus in 2021 at the experimental site in Dengkou County, Bayannur City, Inner Mongolia, and Toketo County, Inner Mongolia Academy of Agricultural Sciences, Hohhot, China. The effects of the four different N application levels on agronomic traits, tuber yield, and clear soil nutrient balance of Cyperus esculentus were analyzed. The number of tillers, plant height, and single leaf area of C. esculentus increased alongside increasing N application, but excessive N application caused above-ground growth of C. esculentus, resulting in lower yield. At the application rate of 150 kg·hm^-2 (N2), Cyperus esculentus exhibited superior agronomic traits, including maximum root length and root volume, the highest whole plant dry weight and tuber yield, and a fresh tuber yield of 9298.87 kg·hm^-2. The apparent nitrogen surplus rates in the two locations were negative at the levels of 0 kg·hm^-2 (N0) and 75 kg·hm^-2 (N1) and positive at the levels of 150 kg·hm^-2 (N2) and 225 kg·hm^-2 (N3). This pattern indicates that nitrogen reached a balanced state at the N2 level in both locations, signifying an optimal nitrogen application rate of 150 kg·hm^-2. RDA analysis showed that tiller number, plant height, single leaf area, maximum root length, root volume, and nitrogen uptake were the main factors driving the formation of dry matter and tuber yield in C. esculentus. Therefore, in northern sandy soil conditions, the application of N at 150 kg·hm^-2 can promote the absorption of nutrients by Cyperus esculentus and maintain the apparent nutrient balance of soil, which is conducive to the growth, development, and yield formation of Cyperus esculentus.

In recent years, there has been considerable attention given to the utilization of urban domestic sludge through the production of sludge alkaline thermal hydrolysis liquid using alkaline hot water lysis. Drought is a major abiotic stress in nature, severely limiting crop production. To effectively mitigate the adverse impact of drought stress on vegetables and explore the potential of sludge utilization, this study used Brassica chinensis as the research object. Different levels of drought stress were induced by creating four soil moisture gradients. Equal amounts of nitrogen from alkaline thermal hydrolysis liquid derived from sludge and urea solution were applied under different levels of drought stress to examine the resistance mechanism of the sludge-derived alkaline thermal hydrolysis liquid to drought stress. The results showed that when exposed to different drought stress conditions, the use of alkaline thermal hydrolysis liquid derived from sludge significantly improved the root length density, root surface area density, and root volume density. This enhancement improved the ability of B. chinensis to absorb water and nutrients from the soil and increased the leaf’s relative water content, helping maintain the plant’s photosynthesis process. Based on the redundancy analysis, applying alkaline thermal hydrolysis liquid to sludge could increase the leaf’s relative water content and improve catalase activity, thereby alleviating the growth inhibition of B. chinensis induced by drought stress. In summary, the application of alkaline thermal hydrolysis liquid in vegetable production can help alleviate growth impediments caused by drought stress on leafy vegetables, provide a strategy for vegetable production in arid areas, and introduce a novel method for the safe and effective utilization of urban sludge.

In this article, using the parameters of hydrological, water resources, and the desertification area of the Shiyang River basin in different periods, the basin hydrology, water resources, desertification, and its changes in the relationship between them were quantitatively studied. It provides the data and the theoretical basis for hydrological, water resource features, and land desertification in this area. The research showed that although the precipitation in the Shiyang River basin had increased from 2005 to 2021, the variability was large and remained at a low level, with an average annual precipitation of only 234.70 mm. From 1993-2004, the annual precipitation at the Caiqi hydrological station reduced, whereas the annual sediment transport increased. The annual precipitation at the Zamusi hydrological station increased from 1999 to 2021, whereas the annual sediment discharge decreased. From 2005 to 2021, the total amount of water resources in the Shiyang River basin decreased by 0.24×10⁸ m³ ·a^-1, but water consumption and water consumption remained at high levels of 24.70× 10⁸ m³ and 17.07×10⁸ m³, with high water consumption and consumption in agriculture, forestry, and fruit industries, exacerbating the irrationality of water resource utilization in the basin. From 1975 to 2014, the total area of desertified land in the basin reduced, but the land changes in different periods and desertification types remained quite different, and the situation of desertification prevention and control in the basin was still grim.

To explore the main soil nutrient characteristics and influencing factors of farmland in the Loess Plateau of Shaanxi, spatial analysis was conducted on the content of SOM, TN, AP, and AK using GIS and geostatistics methods based on the data from 5096 farmland sampling points with a depth of 0-20 cm in the study area. A geographic detector model was used to explore the degree to which 18 influencing factors explained the spatial variation of nutrients. The results showed that the average contents of SOM, TN, AP, and AK were 14.43 g·kg^?1, 0.92 g·kg^?1, 18.21 mg·kg^?1, and 190.28 mg·kg^?1, respectively, showing moderate variation. The four best-fit models for nutrients were all exponential models, with moderate spatial correlation among each nutrient. The combined effect of structural and random factors causes spatial differences in the nutrient content. The global spatial correlation of nutrients is TN > SOM > AK > AP. The regional differences in nutrient content are significant, indicating a gradually increasing trend from north to south. The single-factor effects of annual sunshine duration, annual average temperature, fertilizer use, and geomorphic type have stronger explanatory power for spatial variation in nutrient content but lesser than that of the interaction between the two factors. Research has shown that it is necessary to increase fertilizer input in the northern Shaanxi region, perform intensive cultivation in the Guanzhong region, and consider multiple factors in farmland construction.

To realize the dynamic prediction and quantitative regulation of water resource carrying capacity, an LMDI-SD coupling model based on the LMDI decomposition method, system dynamics (SD), and orthogonal test method was established. The coupling model uses the LMDI decomposition method to identify the driving factors of water consumption change, establishes the SD model to predict the water resource carrying capacity, takes the key driving factors of water consumption change of each department as the regulation index, comprehensively regulates the economic and social water use, and selects the optimal regulation scheme combined with the orthogonal test method. Applied to the dynamic prediction and regulation of water resource carrying capacity in the Guanzhong region between 2020 and 2035, the results show that the following: (1) the intensity effect is the key driving factor for the decrease in agricultural water consumption and the increase in domestic and ecological water consumption in the Guanzhong region between 2010 and 2019, whereas the scale effect is the key driving factor for the increase in industrial water consumption; (2) under the current development mode, the water resource bearing pressure of the whole Guanzhong region and cities will increase yearly from 2020 to 2035, and will be in an overloaded state by 2035 as the increase in total water consumption is far greater than the available water supply; (3) the Han to Wei River Diversion Project effectively alleviated the contradiction between supply and demand of water resources in the Guanzhong area from the supply side. However, compared with the rapidly growing demand, water resources in some cities remain limited; therefore, they should be regulated from the demand side; (4) by restricting the expansion speed of industrial development, improving the level of agricultural water use, and slowing down the growth trend of domestic and ecological water use, the water resources in the Guanzhong region can be bearable from 2020 to 2035. The LMDI-SD coupling model constructed in this study has good practical application value for regional water resource planning and management within the framework of sustainable development.

The biological soil crust is important for maintaining stability in desert ecosystems. Therefore, the use of sand barriers as auxiliary measures to promote the formation and development of biological soil crust in arid areas is of great significance. In this paper, the effects of sand fixation by sand barriers (straw checkerboard, nylon grids, and covered nets) on the formation and development of biological soil crusts were studied using microbial high-throughput sequencing combined with soil physical and chemical properties determination. The results showed that the crust thickness under the covered nets was the thickest, although the colors of the crust in the straw checkerboard and nylon grids were similar to that of the algae crust. The proportions of clay and powder particles in the crust of the three types of sand barriers for sand fixation were significantly higher than that of the moving sand. The nutrition degree of the crust in the covered nets was the highest, indicating the highest degree of soil formation. From the composition analysis of fungi, bacteria, and blue-green algae in crusts from the three types of sand barrier, it was found that the proportions of Cyanobacteria and Leptolyngbya in the crust in the covered nets were higher than those in the crust in the straw checkerboard and nylon grids. In contrast, the proportions of Dothedeomycotes and Microcolleus were lower, and the number of unique microbial OUT was highest. Based on the previous process of soil crust formation and microbial succession in arid areas, it was inferred that the degree of crust development in the cover nets was likely higher than that in the straw checkerboard and nylon grids and that their formation and development trajectory differ. Therefore, among the three types of sand barriers, the covered nets for sand fixation were more suitable for biological soil crust formation and development.

To reveal the soil bacterial community structure and its effects on Cyperus esculentus, affected by different irrigation and salinity treatments in the Qian Gorlos Irrigation District, a random plot sampling experiment was conducted using two-factor, three-level (irrigation level: 50%, 70%, and 100% standard irrigation quota; salt level: control group, mild salinity stress, and moderate salinity stress). Comparative analysis of soil bacterial community characteristics in C. esculentus cropland under different irrigation and salinity treatments was performed. Simultaneously, the molecular ecological network of soil bacteria was constructed to determine the keystone species and its interrelationship with C. esculentus growth. Results showed that (1) The dominant phyla of soil bacteria in C. esculentus cropland were Proteobacteria (22.85% ± 3.80%), Acidobacteriota (20.02% ± 3.21%), and Actinobacteriota (18.85% ± 2.41%). The dominant genera were RB41, Sphingomonas, and Rubrobacter. Bacterial alpha diversity differed insignificantly under different irrigation or salinity treatments (P > 0.05). With increasing irrigation, the relative abundance of Proteobacteria gradually increased, whereas that of RB41 gradually decreased. The same trend was observed with increasing salinity stress. (2) The co-existence relationship between bacterial species was stronger in 100% standard irrigation quota treatments, with a positive correlation rate of 78.05%. Additionally, the degree of interactions and tightness of connections between bacterial species was highest at 50% standard irrigation quota treatments. The highest ecological network complexity and degree of interactions among bacterial communities were found in control group soils, and stronger co-existence relationships among bacterial species were found in moderate salinity soils, with a positive correlation rate of 75.31%. (3) The number of keystone species increased with increasing irrigation. Additionally, the RB41 genus appeared under 70% and 100% standard irrigation quota treatments. Significant differences were observed in keystone species under different salinity stresses. At an S2 salinity gradient, the number of keystone species reached a maximum, with the emergence of the dominant genera RB41 and Lysobacter. The keystone species were Rubrobacter, RB41, Dongia, Steroidobacter, Nitrospira, Lysobacter, and Luteolibacter. (4) Variations in irrigation significantly affected plant height, crown size, number of tillers, above-ground dry weight, carboxylase activity, proline, and superoxide dismutase activities of C. esculentus plants (P < 0.05). Changes in salt application significantly affected plant height, above-ground dry weight, abscisic acid, soluble sugar, peroxidase activity, and malondialdehyde in C. esculentus (P < 0.05). The final screening was performed to conclude that Lysobacter, Nitrospira, Lysobacter, Dongia, RB41, Steroidobacter, and Luteolibacter were significantly associated with the growth and physiological traits of C. esculentus (P < 0.05). The soil bacterial community composition, molecular network, and keystone species were changed as a result of different irrigation or salt treatments, and keystone species were significantly associated with the growth of C. esculentus. This improved information contributes to a better understanding of the soil bacterial community structure and its ecological function in C. esculentus cropland and provides a theoretical basis for adaptive planting and stable and high yield of C. esculentus.

Based on precipitation and soil water isotope data at different elevations in the north and south mountains of Lanzhou from April to October 2018, the lc-excess method and the lc-excess equilibrium equation were used to qualitatively and quantitatively analyze the soil water infiltration process in this area. The infiltration process of soil water, indicated by the soil water lc-excess value, was verified by correlation analysis and single factor analysis. The results showed that there are obvious variations in soil water content in the study area on a monthly scale and at different depths, with loss dominating from April to June and accumulation dominating from July to September. The soil water content in the high altitude areas was found to be greater than that in the low altitude areas, and the soil water content in the north mountains was found to be greater than that in the south mountains. Stable isotopes of soil water at each sampling site we found to be most depleted from August to September. At increasing soil depth, soil water isotopes showed a trend of gradual depletion and stabilization. The soil water lc-excess results showed that the piston flow mode and the priority flow mode co-exist in the infiltration and recharge process of soil water in the study area. The priority flow signal appeared at all sampling sites from July to August. The contribution of the preferred flow pattern to deep soil water was higher at the low elevation sampling sites than at the high elevation sampling sites. The soil water content and soil water lc-excess were found to be positively correlated. The monthly scale and depth of soil water lc-excess were not significantly different between the north and south mountain, indicating that the infiltration and recharge patterns of soil water in the north and south mountains are the same, and that both are dominated by the piston flow infiltration pattern of precipitation recharge. However, in the south mountains, where there is greater vegetation cover, the preferential flow pattern signal appeared more often, especially in July and August, when precipitation is concentrated. Based on the soil water infiltration and replenishment processes in the north and south mountains, it the selection of salt-and drought-tolerant, shallow-rooted shrubs and perennial grasses is recommended for the north mountains, while reasonable irrigation is recommended in the south mountains during the plant growing season (from April to June). The results of this study provide a theoretical reference for understanding the hydrological process in the north and south mountains of Lanzhou.

The Bortala River Basin in Xinjiang is short of water resources and is unevenly distributed in time and space. It is important to quantitatively calculate the conversion rates of the surface water and groundwater in different reaches of the basin and as well as at different periods for the purposes of groundwater exploitation and replenishment and for the optimal allocation of water resources. Based on the daily flow measurement data from five monitored sections in the middle reaches of Bortala River from December 1, 2021, to November 30, 2022, Using river runoff analysis method, combined with the P-III distribution frequency curve, comparisons of water quantity between different monitoring sections, and hydrogeological cross-sections. The relationship between the infiltration rate and the runoff in the leaking river section was also fitted. The results showed that: (1) among the five monitoring stations, Bole Hydrology Station had the largest annual runoff, while Chaxiang Bridge had the smallest; (2) the runoff in the middle reaches of Bortala River was in a normal flow year year of 2022. (3) in the upper part of the middle reaches of the Bortala River, groundwater is converted to recharge surface water; The surface water in the section that runs from the Kundelun canal head to Chaxiang Bridge has a large amount of infiltration to recharge groundwater (infiltration coefficient: 0.67), and the infiltration rate was found to be significantly negatively correlated with the quantity of incoming water; In the lower part, groundwater spilled over the surface. The middle reaches of the Bortala River experienced three conversions of surface water and groundwater, with an overall performance of groundwater overflow supplementing surface water.

In order to further explore the influence of precipitation and soil and water conservation measures on runoff sediment, and to gain an in-depth understanding of the driving factors of water and sand changes in small and medium-sized rivers of the Yellow River, M-K test, Morlet wavelet, linear regression and structural equation modeling were used to study the changes in precipitation and the area of soil and water conservation measures in the upper Guanchuan River from 1957-2021, as well as their the mechanism and process of action were studied. The results showed that annual precipitation showed a non-significant decreasing trend (P >0.05), runoff modulus and sand transport modulus showed a significant decreasing trend (P<0.05), and the area of soil and water conservation measures showed an increasing trend. The response of runoff modulus and sand transport modulus to precipitation got weakened, and the response to soil and water conservation measures was gradually strengthened; the key path of precipitation and soil and water conservation measures affecting the change of water and sand was “area of soil and water conservation measures→runoff modulus”, followed by “area of soil and water conservation measures→runoff→sand transport modulus”, then “precipitation→runoff modulus”, and finally “precipitation→runoff modulus→sand transport modulus”. The total effect of precipitation on water and sand change is 0.42 and 0.38 respectively, while the total effect of soil and water conservation measures on water and sand change is -0.72 and -0.65 respectively. The main factor affecting water and sand change in the watershed is the area of soil and water conservation measures, and the secondary factor is the amount of precipitation.

To explore the characteristics of nutrient and enzyme activity in salt-affected soils of different degrees in the Qaidam Basin, five sampling points along the direction from Chahan Salt Lake to Kunlun Mountains were selected. The soil nutrient and enzyme activity characteristics and their correlations were analyzed. The results showed that soil salinization degree, soil depth, and their interactions significantly affected soil nutrient content and enzyme activity (P<0.05), except for soil total potassium. In soils with lower salinity, nutrient availability (except for available potassium) and enzyme activity were higher and decreased with increasing soil depth. Taking organic carbon and invertase as examples, the contents in the S5 sampling site with the lowest salinity degree were 13.83 g·kg^-1 and 21.01 mg·g^-1·d^-1(0-5 cm), 12.85 g·kg^-1 and 19.29 mg·g^-1·d^-1(5-10 cm), and 9.83 g·kg^-1 and 12.19 mg·g^-1·d^-1(10-20 cm), significantly higher than those in the S1 site with the highest salinity degree, which had 8.56 g·kg^-1 and 1.41 mg·g^-1·d^-1(0-5 cm), 8.40 g·kg^-1 and 1.30 mg·g^-1·d^-1(5-10 cm), and 8.33 g·kg^-1 and 1.26 mg·g^-1·d^-1(10-20 cm). The correlation analysis showed that in lower salinity areas, soil enzyme activity had a significant or extremely significant positive correlation with most soil nutrients (P<0.05). Therefore, differences were observed in the characteristics of soil nutrients and enzyme activity in salt-affected soils of different degrees in the Qaidam Basin. Soil salinization reduces the effectiveness of soil nutrients, inhibits soil enzyme activity, and reduces the decomposition rate of soil organic matter.