Oasis Area Research Articles

Study on the Expansion Potential of Artificial Oases in Xinjiang by Coupling Geomorphic Features and Hierarchical Clustering

The study of the expansion potential of artificial oases based on remote sensing data is of great significance for the rational allocation of water resources and urban planning in arid areas. Based on the spatio-temporal relationship between morphogenetic landform types and the development of artificial oases in Xinjiang, this study explored the development pattern of artificial oases in the past 30 years by using trend analysis and centroid migration analysis, constructing a series of landform–artificial oasis change indices, and investigating the suitability of different landforms for the development of artificial oases based on geomorphological location by adopting a hierarchical clustering method. The following conclusions are drawn: (1) From 1990 to 2020, the area of artificial oases in the whole territory continued to increase, with significant expansion to the south from 2005 to 2010. (2) Six categories of landform types for artificial oasis development were created based on the clustering results. Of these, 7.39% and 6.15% of the area’s geomorphological types belonged to the first and second suitability classes, respectively. (3) The optimal scale for analyzing the suitability of landforms for the development of artificial oases over the past 30 years in the whole area was 8 km, which could explain more than 96% of the changes in the growth of artificial oases. The distribution of landforms of first- and second-class suitability within the 8 km buffer zone of an artificial oasis in the year 2020 was 10.55% and 9.90%, respectively, and landforms of first-class suitability were mainly concentrated in the near plain side of the urban agglomerations located on the northern and southern slopes of the Tianshan Mountains, and the urban agglomerations at the southern edge of Altai Mountains. This study quantified the potential of different geomorphological types for the development of artificial oases and provided a basis for site selection in future artificial oasis planning and urban construction.

Trends in the future evolution of rural settlements in oasis-desert areas under water use simulation scenarios: Take the Hexi Corridor region of China as an example

The uncontrolled expansion of rural settlements caused by the imbalance in the matching of land and water resources has hindered the realization of the goal of sustainable rural development in the oasis-desert area. In this study, “water resources-land resources-oasis rural settlements” are integrated into the same framework of symbiosis development, and the evolution of rural settlements in the context of water and land resources constraints is predicted. We used the coupled “SD-SOS-FLUS” (“system dynamics-suitable oasis structure-future land use simulation”) model to predict the differences in rural settlement sizes and their spatial distribution under the inertial development water use scenario (ID) and sustainable development water use scenario (SD) in the northeast part of the Hexi Corridor in China. In addition, we explored differences in oasis circle structure and land use structure under different water allocation scenarios. Compared with a single model, the coupled model “SD-SOS-FLUS” can better simulate the symbiosis relationship between “water resources-land resources- oasis rural settlements”. Through the prediction, the proportion of water used for production in the ID scenario is still as high as 86.30 %, while the proportion of ecological water use is only 11.50 %, and the continuous imbalance of the water use structure results in the area of arable land and rural settlements will be increased to 7,473.21 km2 and 487.16 km2. It increased by 115.63 km2 and 41.28 km2 respectively compared to 2020, which in turn made the oasis area expanding outward, and the radius R of the oasis also increased from 53.65 km in 2020 to 54.79 km in 2030. The area of arable land and rural settlements under water and land resource constraints in the SD scenario decreased to 5223.56 km2 and 105.04 km2. The contraction of the oasis increases the transition zone circle width B2 from 19.88 km in 2020 to 24.58 km in 2030, an increase of 5 km compared to the ID scenario. As a result of the spatial reconfiguration, the number of rural settlement patches decreased from 1.04 × 104 to 0.15 × 104 in 2020, saving 3.41 × 104 ha of land after optimization.

Film mulching counteracts the adverse effects of mild moisture deficiency, and improves the quality and yield of Cyperus esculentus. L grass and tuber in the oasis area of Tarim Basin.

Plastic film mulching (PFM) and deficit irrigation (DI) are vital water-saving approaches in arid agriculture. Cyperus esculentus is a significant crop in dry zones. However, scant data exists on the impacts of these water-saving methods on C. esculentus yield and quality. Using randomized block experiment design. Three irrigation strategies were tested: CK (standard irrigation), RW20 (20% water reduction), and RW40 (40% water reduction). Mulchin treatments included film mulching (FM) and no film mulching (NFM). Results revealed substantial effects of film mulching and drip irrigation on soil nutrients and physical properties, with minor influence on grass, root, and tuber stoichiometry. PF treatment, DI treatments, and their interaction significantly affected C. esculentus forage and tuber yields. Initially, grass and tuber yields increased and then decreased with reduced irrigation. The highest yields were under RW20 (3716.31 and 4758.19 kg/ha). FM increased grass and tuber yield by 17.99% and 8.46%, respectively, over NFM. The water reduction augmented the biomass distribuiton of the leaf and root, while reducing the tuber biomass in NFM. FM significantely impacted grass ether extract content, while reduced water influenced grass and tuber crude protein and tuber ether extract content. Mild water stress increased ether extract, crude protein, and soluble matter in grass and tubers, while excessive RW decreased them. Integrating soil traits, nutrients, yield, and quality, findings indicate C.esculentus yield and quality primarily hinge on soil water content, pond hydrogenase, and electrical conductivity. Based on this results, the recommended strategy is to reduce irrigation by 20% for cultivating C. esculentus in this area.

Unveiling the Dynamics and Influence of Water Footprints in Arid Areas: A Case Study of Xinjiang, China

A prerequisite for the rational development and utilization of regional water resources is the measurement of water stress. In this study, from the perspective of water footprints, we took the proportion of the agricultural water footprint within the total water resource usage of Xinjiang (hereafter referred to as XJ) as an example to measure its water stress index and explore the state of water stress in the region and its corresponding driving factors. The ESDA method was applied to characterize the spatial patterns of and correlations with water stress. The effects of different factors on the spatial differentiation between the water footprint and water stress were quantified using the LMDI and geoprobes, respectively. The results showed that (1) both the agricultural water footprint and the water stress index in XJ showed an upward trend, the spatial distribution of water stress was uneven, and the regional pressure difference between the east and the west was greater than that between the north and the south; (2) the water stress index has an obvious negative spatial correlation, fluctuations in its discrete nature have been enhanced, and the number of spatially correlated prefectures is decreasing; (3) water consumption of CNY 10,000 GDP, GDP per capita, and total CO2 emissions have the most significant impact on the evolution of the agricultural water footprint in XJ. Meanwhile, spatial variations in water stress are mainly determined by the area of cultivation, the area of natural oasis, and the proportion of water used in agriculture. Analysis of the characteristics of and factors influencing water stress in XJ from the perspective of its agricultural water footprint provides a new perspective for further analyzing the actual state of the water footprint and water stress in XJ and supplies a reference basis for the decision-makers of the XJ government.

Analysis of human health effects under ozone exposure in the oasis area of Hetao Plain.

This article, based on OMI data products, utilizes spatial distribution, ozone-sensitive control areas, Pearson correlation methods, and the Ben-MAP model to study the changes in ozone column concentration from 2018 to 2022, along with the influencing factors and the health of populations exposed to ozone. The findings suggest a spatial variation in the ozone column concentration within the study area, with an increasing trend observed from west to east and from south to north. Over time, the ozone column concentration exhibits an initial increase followed by a subsequent decrease, with the peak concentration observed in 2019 at 37.45 DU and the nadir recorded in 2022 at 33.10 DU. The monthly mean distribution exhibits an inverted V-shaped pattern during the warm season from April to September, with a peak in July (46.71 DU) and a trough in April (35.29 DU). The Hetao Plain Oasis area is primarily a NOx control area in sensitive control areas. The concentrations of O3 and precursor HCHO exhibited significant positive correlations with vegetation index and air temperature, while showing significant negative correlations with wind speed and air pressure. The precursor NO2, in contrast, exhibited a significant negative correlation with both the vegetation index and relative humidity. Based on the ground-based monitoring sites and analysis of human health benefits, the study area witnessed 1944.45 deaths attributed to warm season O3 exposure in 2018, with a subsequent reduction in premature deaths by 149.7, 588.2, and 231.75 for the years 2019 to 2021 respectively when compared to the baseline year. In 2021, the observed decrease in warm-season O3 concentration within that region compared to 2018 resulted in a significant reduction, leading to the prevention of 126 premature deaths.

Root Distribution and Water Uptake Applied by Hydrogen and Oxygen Stable Isotopes for Lianas in Northwest China

The root distribution and water uptake of irrigated vines (Vitis vinifera L.) in arid oasis areas remain poorly understood, particularly in terms of the variations in water uptake resulting from plant type and growing period. In this study, excavation and soil coring were employed to investigate the root distribution of vines. Meanwhile, the water uptake dynamics of irrigated vines in an arid oasis area were developed using stable isotopes of hydrogen and oxygen in water bodies (δD and δ18O) and in crops and soil water, coupled with a direct inference approach and a linear mixed model (IsoSource). The soil layers were divided into nine layers via hierarchical cluster analysis. The results indicated that the vertical distributions of the total and fine roots of grapevines were mainly in the range of 40–160 cm, accounting for 93.1% (91.2%) and 92.5% (90.0%) of the total root (200 cm) distribution during May and October, respectively. In the horizontal direction, both the total root and fine root systems were mainly distributed within 0–100 cm from the trunk and contributed 81.2% and 79.8% of the total root distribution, respectively. Meanwhile, both the total root weight (length) density and fine root weight (length) density decreased gradually with increasing radial distance from the trunk in the 0–80 cm range. The main water uptake of vines was at 0–40 cm in June, 20–80 cm in July, and 40–100 cm in August. These findings suggest that the main depth of root water uptake increases during the whole growth stage for grapevines in arid oasis ecosystems. This information will help growers to improve irrigation efficiency and provide a data analysis of water conservation in an arid oasis area during water stress.

Soil Microbial Community Structure and Functional Diversity Character of Abandoned Farmland in Minqin Oasis

To clarify the impact of the structure and function of soil microbial communities in the stage of abandoned farmland, three different stages of land abandoned in desert oasis areas were selected as the research objects. We used metagenomic sequencing technology to research soil microbial community structure and functional diversity characteristics of different stages of abandoned farmland. The results showed that there were significant differences in the relative abundance of the dominant phyla Actinobacteria, Proteobacteria, and Gemmatimonadetes in the soil of the three stages of returning farmland. Compared with that in the early stage of abandoned farmland, the later stage of abandoned farmland restoration increased the gene proportion involved in Quorum sensing, porphyrin and chlorophyll metabolism, pantothenate and CoA biosynthesis, and styrene degradation, and there was a significant difference in relative abundance (P<0.05), which indicated that different stages of abandoned farmland had changed the functional potential of the nutrient cycle and energy metabolism in soil microbial communities. The RDA results showed that EC, AK, and TN had a significant impact on the functional composition of soil microbes, and soil EC had the greatest impact on microbial functional composition. The results showed that different stages of abandoned farmland had a significant impact on the soil microbial community structure and functional composition. In the ecological restoration of abandoned farmland in Minqin Oasis, the sensitivity of microbial community structure and functional composition to soil restoration at different stages should be considered using comprehensive relevant indicators.

Evaluation of the Evolution of the Ecological Security of Oases in Arid Regions and Its Driving Forces: A Case Study of Ejina Oasis in China

Ecological security is an important guarantee of human security and survival, closely related to sustainable development. However, the ecological security evaluation and driving force analysis of oases in arid areas is still insufficient. Ejina Oasis’s ecological security has experienced significant shifts following the centralized management of the Heihe River’s water allocation. Understanding the shifts in ecological security in the Ejina region is paramount for the oasis’s long-term sustainability. This paper employed the Pressure–State–Response (P–S–R) model to select socioeconomic and ecological indicators, establish a comprehensive ecological security evaluation index system, and then analyze the evolving ecological security in the region. Additionally, this paper explored the relationship between changes in the water area, oasis area, and ecological security by using the gray correlation degree to quantify the influence of Land Use Changes (LUCCs) on the overall ecological security. From 2000 to 2012, the ecological security index of Ejina Oasis remained relatively stable at around 0.4. However, a noticeable upward trend in the ecological security index emerged from 2012 to 2020, indicating a shift toward improved ecological security in the region. Critical determinants of this change included the habitat degradation degree, total population, habitat quality, carbon stock, fractional vegetation cover (FVC), the proportion of tertiary industry, and the volume of water discharged from Wolf Heart Mountain. The degree of habitat degradation, fractional vegetation cover (FVC), and the proportion of tertiary industry had the greatest impact on the change in ecological security. The pressure index was dominant in influencing ecological security before 2012 but gradually transitioned to the state index. This study offers a valuable framework for assessing the intricate relationship between LUCCs and ecological security in water-scarce, arid-region oases.

Simulation and Assessment of Daily Evapotranspiration in the Heihe River Basin over a Long Time Series Based on TSEB-SM

The high spatial and temporal resolution of recently developed evapotranspiration (ET) products facilitates agricultural water-savings in irrigated areas as well as improved estimates of crop yield, especially in arid and semi-arid regions. However, cloud cover interferes with ET estimates, in particular when using thermal-infrared-based models in temperate and tropical regions. Previous studies have shown that the two-source energy balance (TSEB) model coupled with soil moisture (TSEB-SM) has great potential for estimating surface ET by overcoming this issue. In this study, the TSEB-SM model was first used to generate a spatiotemporally continuous 1 km daily ET dataset across the Heihe River Basin in China from 2000 to 2020, which was then evaluated against four spatially distributed sites (Arou, Huazhaizi, Daman, and Sidaoqiao) and further compared with the two most widely used daily ET datasets (PML-V2 (Penman–Monteith–Leuning) and SEBAL (surface energy balance algorithm for land)). The results showed that the newly developed ET dataset agrees well with ground-based observations and outperforms the PML-V2 and SEBAL products in precisely characterizing the seasonal fluctuations and spatial distribution as well as the spatiotemporal trends of ET. In particular, ET in the Heihe River Basin exhibits clear regional differences. The upstream and midstream grassland and irrigated oasis areas provide much higher annual ET than the downstream desert areas, with a difference of up to 600 mm/year. A three-cornered hat (TCH)-based pixel-by-pixel analysis further demonstrated that the TSEB-SM and PML-V2 products have substantially smaller relative uncertainties as compared to SEBAL ET. In general, the proposed ET datasets are expected to be more beneficial for irrigation scheduling and to provide more efficient water management across the Heihe River Basin.

Three Decades of Oasis Transition and Its Driving Factors in Turpan–Hami Basin in Xinjiang, China: A Complex Network Approach

As a predominant ecosystem-providing area and distinctive landscape in arid regions, an oasis plays an important role in maintaining land stability, human production, and daily activities. Studying the dynamics of oasis and its driving factors is vital to supporting arid regions’ sustainable development. As a typical mountain–desert–oasis landscape, the Turpan–Hami (Tuha) Basin, located in Xinjiang, China, includes complex interactions among different land types. For this study, we revealed the spatio-temporal patterns and transition processes of the oasis using a complex network method between 1990 and 2020 in the Tuha Basin. In the oasis transition network, the degree value, betweenness centrality, and average path length were calculated to express the transition relationship, key oasis type, and oasis structural stability, respectively. Six factors related to climate change and human actives were selected to investigate the driving forces behind oasis transitions, including the average temperature and precipitation in the growing season, the total power of agricultural machinery (TAMP), the production of raw coal (PRC), the total output value of the plantation industry (TPI), and the population (Pop). Our results show that the oasis area of the Tuha Basin, including the natural oasis and artificial oasis, all grew from 1990 to 2020, with the natural oasis expanding more than the artificial oasis. The transitions between oasis types became more frequent as the area of oasis land types increased throughout the study period. Grassland acted as the most important oasis type in the network, with the highest betweenness centrality, but its importance declined due to the increasing complexity of the oasis transition network from 1990 to 2020. The transitions between oasis types became simpler, and the oasis structural stability decreased. Through driving force analysis, the oasis changes showed a positive correlation with the temperature (p-value &lt; 0.05, r = 0.88), and urbanization and industrialization factors prompted transitions to built-up areas and cropland from grassland and shrubland. In summary, our results suggest that to create a harmonious symbiotic relationship between the natural environment in dryland and human activities, preventing grassland degradation and excessive reclamation of land cover is an available way. Meanwhile, the protection of shrubland and water resources is also important. This study provided reference and theory support for promoting the sustainable development of oases.

Assessment of the human footprint in Antarctica: A case study Larsemann Hills

The article is devoted to assessment of the anthropogenic influence in the Larsemann Hills, East Antarctica. The emission of the main pollutants and greenhouse gases from diesel generators used at Antarctic stations are estimated for the period since the beginning of the development of the oasis area (from 1986 to 2019). It is shown that SO2 emissions decreased in 2019 compared to peak values in 1990 by 5.6 times, which was due to a significant decrease of the sulfur content in fuel. Emissions of other pollutants mostly increased. Surface air pollution by SO2, NO2, CO, PM10 and black carbon (BC) using the AERMOD dispersion model are characterized. It is revealed that the most significant emission health impact is due to increase of surface concentrations of nitrogen dioxide. Deposition fluxes of PM10 and BC are estimated. The fluxes of PM10 and BC dry deposition in the territory of Larsemann Hills can reach maximum values of 27.5 and 21.7 mg/m2/year, respectively; can be traced in certain directions at a distance of up to 2.0 km or more. Modeling of BC deposition due to the dispersion of emission allowed to make draft estimates of soot concentration in the snow of the area and resulting radiative forcing climatic effects.

A study on matching supply and demand of ecosystem services in the Hexi region of China based on multi-source data.

To achieve the best management of the ecosystem and sustainable socioeconomic development, it is crucial to clarify the matching relationship between the supply and demand of ecosystem services (ESs). Four types of ESs were chosen for the Hexi region in this study: food supply, carbon sequestration, water yield, wind erosion control and sediment retention. We assessed the supply-demand and matching relationships of different ESs using the Integrated Valuation of Ecosystem Service and Tradeoffs (InVEST) model, the ESs supply-demand ratio and the four-quadrant model. Moreover, we also analyzed the supply-demand ratio of integrated ESs and their cold spots. The findings suggest that (1) from 2000 to 2020, the average supply of food supply, carbon sequestration, water yield, wind erosion control and sediment retention increased by 44.31t/km2, 128.44t/hm2, 14,545.94m3/km2 and 0.14kg/m2 respectively, which showed a spatial pattern of "high in the southeast and low in the northwest". The average demand for food supply and carbon sequestration increased by 1.33t/km2 and 0.32t/hm2 respectively, while the average demand for water yield and wind erosion control and sediment retention decreased by 2997.25m3/km2 and 1.19kg/km2 respectively. The spatial distribution is consistent with the layout of population density, production and residential areas, and fragile ecological areas. (2) The supply-demand ratio of food supply, carbon sequestration and water yield is greater than 0.095, which is in a state of oversupply, and the supply-demand ratio of wind erosion control and sediment retention is less than 0, which is in a state of shortage; all ESs are mainly in low-low spatial matching areas, mainly concentrated in the desert areas of the northwest in the Hexi region. (3) The supply-demand ratio of integrated ESs increased by 0.024, and the proportion of cold spots and sub-cold spots was more than 50% and concentrated in the northwest, while hot spots and sub-hot spots accounted for only about 16%, mainly distributed in the southern Qilian Mountains and some oasis areas.

Controlling Factors of Groundwater Salinization and Pollution in the Oasis Zone of the Cherchen River Basin of Xinjiang

Groundwater is a vital resource for local human life and production in the oasis zone of the Cherchen River Basin of Xinjiang. Understanding the controlling factors of groundwater salinization and pollution is of great significance for the sustainable utilization of groundwater resources and protection of the ecological environment in desert oasis areas. In light of this, a total of 36 single structure unconfined groundwater samples and 54 multi-layered structure unconfined and confined groundwater samples were collected from the oasis zone of the Cherchen River Basin and evaluated for the distribution characteristics and pollution status of major ions. Hydrogeochemical methods (e.g., Piper diagram, multivariate statistics, Gibbs model, and relationships among ions) were used to determine the main controlling factors of groundwater salinization and pollution. Differences in hydrogeochemical zonation were found from the single structure unconfined aquifers in sloping plains of piedmont areas to the multi-layered structure unconfined and confined aquifers in alluvial-proluvial plain areas, and Cl-Na (87.8%) was the main hydrochemical type in the groundwater of the study area. The quality of single structure unconfined groundwater was starkly better than that of the multi-layered unconfined and confined groundwater, which was mainly caused by Na+ (mean value of 9 969 mg·L-1), Cl- (13 687 mg·L-1), and SO42- (5 840 mg·L-1). Moreover, the natural hydrogeochemical process was the main reason for the deterioration of groundwater quality. The hydrochemistry was mainly controlled by the water-rock interaction and evaporation processes. The mineral dissolution of silicates and evaporites was an important source of chemical ions in the groundwater. Furthermore, the chemical weathering of evaporites combined with the processes of evaporation and cation exchange had a significant influence on the salinization of multi-layered unconfined and confined groundwater in alluvial-proluvial plain areas. In addition, synthetic fertilizers were the main pollution sources of NO3- in groundwater in the intensive agricultural zones.

Disparities between climate change facts and farmer’s awareness and perception in an arid region: A case study of the middle and lower reaches of the Heihe River Basin in northwest China

Arid areas are sensitive and vulnerable to climate change and may face more climate risks in the future under the background of global warming. The adaptability of society to future climate change impacts relies heavily on the awareness and perception of local populations. This study focuses on the middle and lower reaches of the Heihe River, which is the second-largest inland river in China, and examine the temperature and precipitation changes from 1981 to 2020, employing the Sen + Mann-Kendall trend analysis method. The local farmers and herdsmen were interviewed, and their variations in awareness and perception regarding climate change were assessed. The results show that local residents are highly sensitive to climate warming but not to precipitation increases, indicating that the communities faces substantial constraints imposed by limited water resources. Residents of the downstream desert area feel a wetter climate than those of the mountain and oasis areas in the middle reach, suggesting a greater water scarcity pressure in the latter. The increased allocation of ecological water to the downstream portion of the Heihe river, as implemented by the “97″ water distribution plan in 2000, may be a contributing factor to this phenomenon. The disparities in the fact and residents’ awareness and perception of climate change are different among the mountainous, oasis, and desert regions, which are influenced by regional differences in climate change, agricultural production conditions, and water policies. The government should consider these factors when formulating water policies to ensure successful and balanced development.

Optimizing irrigation and nitrogen application strategies to improve sunflower yield and resource use efficiency in a cold and arid oasis region of Northwest China.

In arid regions, water scarcity, land degradation and groundwater pollution caused by excessive fertilization are the main constraints to sustainable agricultural production. Optimizing irrigation and fertilizer management regime is an effective means of improving crop water and fertilizer productivity as well as reducing negative impacts on the ecosystem. In order to investigate the effects of different irrigation and nitrogen (N) fertilizer rates on sunflower growth, yield, and water and N use efficiency, and to determine the optimal water and N management strategy, a two-year (2021 and 2022) field experiment with under-mulched drip irrigation was conducted in the Hexi Oasis area of Northwest China. The experiment design comprised three irrigation levels (W1, 55%-65% FC, where FC represents field water capacity; W2, 65%-75% FC; W3, 75%-85% FC) and three N application levels (N1, 120kg ha-1; N2, 180kg ha-1; N3, 240kg ha-1), resulting in a total of nine treatments. The findings indicated that increasing irrigation and N application rates led to improvements in leaf area index (15.39%-66.14%), dry matter accumulation (11.43%-53.15%), water consumption (ET, 1.63%-42.90%) and sunflower yield (6.85%-36.42%), in comparison to the moderate water deficit and low N application (W1N1) treatment. However, excess water and N inputs did not produce greater yield gains and significantly decreased both water use efficiency (WUE) and nitrogen partial factor productivity (NPFP). Additionally, a multiple regression model was developed with ET and N application as explanatory variables and yield, WUE and NPFP as response variables. The results based on the regression model combined with spatial analysis showed that an ET range of 334.3-348.7 mm and N application rate of 160.9-175.3 kg ha-1 achieved an optimal balance between the multiple production objectives: yield, WUE and NPFP. Among the different irrigation and N management strategies we evaluated, we found that W2N2 (65%-75% FC and 180kg N ha-1) was the most fruitful considering yield, resource use efficiency, etc. This result can serve as a theoretical reference for developing appropriate irrigation and N fertilization regimes for sunflower cultivation in the oasis agricultural area of northwest China.

Mechanism analysis of vegetation phenology in an urban agglomeration in an arid zone driven by seasonal land surface temperatures

In arid areas, vegetation is the habitat that sustains the life and survival of species, and it also plays a vital role in soil erosion prevention. This paper investigates the spatial aggregation patterns and trends of vegetation phenology (VP) and land surface temperature (LST) from 2002 to 2021. Additionally, the spatial Durbin model was used to analyze seasonal elements such as air temperature, evaporation, LST, precipitation, soil moisture, aerosol optical depth, and the impact of DEM on VP. Finally, explore the relationship between seasonal LST and urbanization and VP. The results show that in arid areas, the vegetation start of season time (SOS) showed an advancing trend, the vegetation end of season time (EOS) and length of season time (LOS) showed an extending trend, and the vegetation time of middle of season (MOS) tended to be stable. VP changes in oasis areas fluctuated significantly, while VP varies in non-oasis regions were stable. Under the scenario of spatial heterogeneity, LST is the most influential factor in VP. Spring LST has the greatest impact on SOS, winter LST on EOS and LOS. Urbanization advances SOS and extends EOS but has less impact on LOS. This study's results are essential for understanding the complex mechanism of VP changes in oases in arid regions and analyzing the distribution characteristics of VP under urbanization levels.

Effects of Different Mulch Types on Farmland Soil Moisture in an Artificial Oasis Area

Different types of mulch are often used in agricultural production to enhance soil moisture and improve crop yields. The question of which mulch provides superior water retention in arid regions, where water resources are scarce, is a major concern for agricultural production. We conducted observations and studies at a typical irrigated experimental station in an arid zone with four types of mulch, including liquid mulch (LM), biodegradable mulch (BM), ordinary black mulch (OBM), and ordinary white mulch (OWM), and plots with no mulch. Samples were collected and analyzed at 1, 3, 5, and 7 days after each rainfall or irrigation to obtain soil moisture changes and to analyze the effect of different mulches on soil moisture retention. The results showed that mulch cover was effective in retaining soil moisture compared to plots without mulch cover. Specifically, soil moisture was highest in the farmland with OWM during the observation period. OWM, OBM, and BM were all effective in reducing soil water evaporation and maintaining soil moisture. LM and BM were capable of utilizing rainfall to recharge soil water in a superior way, and polyethylene mulches (OBM and OWM) had a significant barrier impact on rainfall.

Simulation of the Spatial Flow of Wind Erosion Prevention Services in Arid Inland River Basins: A Case Study of Shiyang River Basin, NW China

Wind erosion is a key global environmental problem. As an important protective measure to provide services to the ecosystems in wind-eroded areas, the wind erosion prevention service is of great significance to the management of wind and sand hazards and ecological environment restoration in the wind-eroded areas and the neighboring areas. Taking the Shiyang River basin as the study area, the quality of supplies for wind erosion prevention services was estimated using the RWEQ model for the years 2005, 2010, 2015, and 2020; the trajectories of air masses at wind speeds higher than the sand-causing wind speeds were simulated based on the forward trajectory module of the HYSPLIT model for a 24 h period; the spatial simulation of the flow of wind erosion prevention services on a daily scale with Minqin Station as the sand source was carried out; and the beneficiary areas of wind erosion prevention services were identified. Based on the RWEQ model, the spatial patterns of potential wind erosion, actual wind erosion, and wind and sand stabilization services were obtained, and the supply areas were divided. From 2005 to 2020, the wind erosion prevention service flow in the Shiyang River basin was distributed along a northwest–southeast direction, with a radial decrease from the center to the periphery, and with an extremely strong extraterritorial effect. The amount of wind erosion in the basin has a variable downward tendency over time and a spatial distribution pattern of high in the north and low in the south. The area of higher sand fixation is distributed in the eastern oasis area and desert junction zone. The HYSPLIT model was used to simulate the transport paths of wind and sand within 24 h during 2005–2020, the transmission paths of the wind erosion prevention service flow were obtained to be 59–134, and the flows were 2.55 × 104–3.85 × 106 t, displaying a changing trend of first decreasing, then increasing, and then decreasing. Gansu Province, Ningxia Hui Autonomous Region, and Inner Mongolia Autonomous Region are the most important areas benefiting from the wind erosion prevention service flow in the Shiyang River basin. The wind erosion prevention service flows in the basin benefit 47 cities in 9 provinces.

Quantifying recharge sources to groundwater to an oasis area: Implications for strengthening water resource management under changing environmental conditions

AbstractIn order to implement sustainable management of water resources in the Desert Oasis, it is necessary to quantify the changes in the groundwater recharge process. Using the Cl−, stable hydrogen and oxygen isotope datasets extracted from 113 groundwater samples in the years of 2000 and 2020, and combining these with the MixSIAR model, changes in the groundwater recharge process and recharge source contributions in the Minqin Oasis (MO) in northwestern China area before and after ecological treatment were quantitatively analysed. Overall, confined groundwater was the greatest contributor to the recharge of shallow groundwater in the MO area in 2000. However, after 10 years of ecological rehabilitation, surface water has become the most important recharge source of shallow groundwater, with its contribution increasing by 10.6% between 2000 and 2020 ~ 2021. River water diversion projects have reversed falling groundwater levels in the MO area. Of these projects, that in the MO has seen groundwater levels rise at a rate of 0.09 m·year−1 from 2008 to 2019. This coincides with the increase in the contribution of surface water to groundwater recharge in 2020. In addition, insignificant changes were observed in the contributions made by lateral groundwater flow to groundwater recharge in the MO area in the years of 2000 and 2020 ~ 2021, indicating that groundwater in the upper and middle reaches of the MO area have contributed very little to the restoration of groundwater levels in the area's lower reaches. All these factors would appear to indicate that regional ecological management has had a lasting impact, and that the exploitation of groundwater in this desert oasis area in an inland river basin should be based upon rational planning and integrated, comprehensive management strategies.

Ecological Security of Desert–Oasis Areas in the Yellow River Basin, China

The desert–oasis interaction zone plays a crucial role in safeguarding oasis ecological security and maintaining stability within oases. This paper proposed a framework of EN-DSS, based on long-term remote sensing data and fundamental data, adopted morphological spatial pattern analysis (MSPA) and Linkage Mapper among other methods, and it took Lingwu City in the Ningxia Hui Autonomous Region, which is located in the desert–oasis interaction zone in the upper reaches of the Yellow River, as a case study. The results indicate the following: since 1995, this desert–oasis system has exhibited the characteristics whereby the oasis is expanding eastward and the desert is significantly receding. The vegetation coverage has improved overall, forming an ecological security pattern characterized predominantly by shrub forests, which is referred to as the “one core, two corridors, three zones, and multiple clusters” pattern. This pattern has significantly reduced the risk of wind and sand erosion in the agricultural irrigation areas along the Yellow River. However, the construction of this ecological security pattern still faces challenges, including high construction and maintenance costs and the need to enhance the network’s quality. In the future, it will be necessary to strengthen the integrated ecological network construction of ecological areas, agricultural areas, and urban areas to enhance the stability of this regional ecological network system.