Search Results (28)

The Tarim River Basin (TRB) faces significant ecological challenges due to global warming, making it essential to understand the changes in the climates of its sub-basins for effective management. With this aim, data from national meteorological stations, ERA5_Land, and climate indices from 1961 to 2021 were used to analyze the temperature and precipitation variations in the TRB and its sub-basins and to assess their climate sensitivity. Our results showed that (1) the annual mean temperature increased by 0.2 °C/10a and precipitation increased by 7.1 mm/10a between 1961 and 2021. Moreover, precipitation trends varied significantly among the sub-basins, with that in the Aksu River Basin increasing the most (12.9 mm/10a) and that in the Cherchen River Basin increasing the least (1.9 mm/10a). Moreover, ERA5_Land data accurately reproduced the spatiotemporal patterns of temperature (correlation 0.92) and precipitation (correlation 0.72) in the TRB. (2) Empirical Orthogonal Function analysis identified the northern sections of the Kaidu, Weigan, and Yerqiang river basins as centers of temperature sensitivity and the western part of the Kaidu and Cherchen River Basin as the center of precipitation sensitivity. (3) Global warming is closely correlated with sub-basin temperature (correlation above 0.5) but weakly correlated with precipitation (correlation 0.2~0.5). TRB temperatures were found to have a positive correlation with AMO, especially in the Hotan, Kashgar, and Aksu river basins, and a negative correlation with AO and NAO, particularly in the Keriya and Hotan river basins. Precipitation correlations between the climate indices were complex and varied across the different basins. Full article

An accurate understanding of the structure of spatial correlation networks of land use carbon emissions (LUCEs) and carbon balance zoning plays a guiding role in promoting regional emission reductions and achieving high-quality coordinated development. In this study, 42 counties in the Tarim River Basin from 2002 to 2022 were chosen as samples (Corps cities were excluded due to missing statistics). The LUCE spatial correlation network characteristics and carbon balance zoning were analyzed by using the Ecological Support Coefficient (ESC), Social Network Analysis (SNA), and Spatial Clustering Data Analysis (SCDA), and a targeted optimization strategy was proposed for each zone. The results of the study indicate the following: (1) The LUCEs showed an overall upward trend, but the increase in LUCEs gradually slowed down, presenting a spatial characteristic of “high in the mid-north and low at the edges”. In addition, the ESC showed an overall decreasing trend, with a spatial characteristic opposite to that of the LUCEs. (2) With an increasingly close spatial LUCE correlation network in the Tarim River Basin, the network structure presented better accessibility and stability, but the individual network characteristics differed significantly. Aksu City, Korla City, Bachu County, Shache County, Hotan City, and Kuqa City, which were at the center of the network, displayed a remarkable ability to control and master the network correlation. (3) Based on the carbon balance analysis, the counties were subdivided into six carbon balance functional zones and targeted synergistic emission reduction strategies were proposed for each zone to promote fair and efficient low-carbon transformational development among the regions. Full article

The Aksu River Basin is located in the western region of the middle part of the southern foothills of the Tianshan Mountains and the northwestern edge of the Tarim Basin in Xinjiang, China. High-arsenic (As)/high-fluoride (F) groundwater is widely distributed in this area and is harmful to the life of local residents and to agricultural production. It is of great importance to understand the distribution and causes of As-F co-enrichment in the groundwater in this area. Based on the test results of 138 groundwater samples in the plain area of the Aksu River Basin, the hydrochemical characteristics of groundwater and the spatial distribution of As-F co-enrichment groundwater were analyzed under the following conditions: a single-structure phreatic aquifer (SSPA), a phreatic aquifer in a confined groundwater area (PACGA), a shallow confined aquifer (SCA), and a deep confined aquifer (DCA), all in a recharge area, transition area, and an evaporation area. The hydrogeochemical processes affecting the source, migration, and enrichment of As-F in the groundwater were revealed. The results showed that the chemical types of groundwater in the study area were mainly HCO₃·SO₄-Ca·Mg and SO₄·Cl-Na·Mg. Horizontally, high-As-F groundwater was mainly distributed in the transition area and evaporation area in the middle and lower reaches of the Aksu River Basin. The area is close to the edge of the desert, where the groundwater runoff is sluggish and in an alkaline-reducing groundwater environment. Vertically, high-As groundwater was mainly distributed in the PACGA at a depth of 10–20 m and in the SCA at a depth of 80–100 m. High-F groundwater was mainly concentrated in the PACGA at a depth of 10–30 m and in the SCA at a depth of 80–100 m, and As-F co-enrichment groundwater was mainly concentrated in the PACGA at a depth of 10–20 m and in the SCA at a depth of 80–100 m. The hydrochemical characteristics of the groundwater in the Aksu River Basin were closely related to geological conditions, hydrogeological conditions, and the hydrochemical environment of the groundwater. As-F co-enriched groundwater was mainly affected by the combination of a small topographic gradient, a shallow groundwater burial depth, a weak reducing alkaline groundwater environment, strong evaporation and concentration, the weathering and dissolution of evaporated salt rock, and the alternating adsorption of cations. Full article

Water system connectivity is an important measure to optimize the balanced spatial allocation of water resources and water security patterns. Inland river basins in arid zones are generally insufficiently connected, so the scientific evaluation of the current status of water system connectivity and the centrality of its nodes in the water system network has practical significance for the scientific construction of regional water networks. Taking the Tarim River Basin in Xinjiang, China, as an object, this study conducted a comprehensive evaluation of basin water system connectivity by constructing a water system connectivity evaluation system with a total of 12 indicators for the three aspects of pattern connectivity, structural connectivity and functional connectivity. Subsequently, the TOPSIS model, with combined weights of the analytic hierarchy process and the entropy weight method, was used to comprehensively evaluate the connectivity of the watershed’s water system. The research evaluated the node centrality of the water system network that was closely related to the basin water system connectivity by using complex network analyses. The study results indicated the following: (1) among the source streams in the Tarim River Basin, the connectivity of the Aksu Basin was the best and that of the Keriya Basin was the worst and (2) the distribution patterns of the eigenvector centrality and betweenness centrality of the basin hydrological network nodes were similar, with nodes of highest centrality concentrated in the vicinity of the mainstems and the source–mainstem intersections. This work provides a basis and reference for the construction of water system connectivity and the selection of key control sections for ecological flow in the Tarim River Basin. Full article

Research on evapotranspiration and its drivers in the Aksu River Basin from the perspectives of climate change and land use is of great significance for promoting the efficient use and precise allocation of its water resources. Theil-Sen median trend analysis (T-S) and the Mann–Kendall nonparametric test (M-K), in addition to correlation analysis, partial correlation analysis, complex correlation analysis, and driving-factor zoning principles, were used to examine the characteristics of the spatiotemporal changes in evapotranspiration and to explore the driving mechanism of the changes in evapotranspiration. The results indicated that the range of fluctuations in the multiyear average evapotranspiration in the Aksu River Basin from 2001 to 2020 was between 481.58 and 772.37 mm/a, which showed the spatial distribution characteristics of being high in the west and central part of the basin, and low in the north and south of the basin. The positive correlation between evapotranspiration and precipitation was stronger, and the negative correlations with temperature and relative humidity were stronger. The change in evapotranspiration in cultivated land is mainly driven by precipitation and relative humidity × precipitation; for grassland, the main drivers were relative humidity and precipitation × relative humidity; for woodland, the main drivers were relative humidity and other climatic factors; and for other land types, the main drivers were other climatic factors. Full article

The response of dryland vegetation to climate change is particularly sensitive in the context of global climate change. This paper analyzes the characteristics of spatial and temporal dynamics of vegetation cover in the Tarim River Basin, China, and its driving factors in order to investigate the response of vegetation growth to water storage changes in the basin. The Enhanced Vegetation Index (EVI), the GRACE gravity satellite, and meteorological data from 2002 to 2022 are used to decipher the characteristics of the response of water storage changes to vegetation changes, which is of great significance to the realization of regional ecological development and sustainable development. The results of the study show the following: (1) The vegetation in the Tarim River Basin has an overall increasing trend, which is mainly distributed in the Aksu Basin and the Weigangkuche River Basin and is spatially distributed in the form of a ring. (2) Vegetation distribution greatly improved during the 20-year study period, dominated by high-cover vegetation, with a change rate of 200.36%. Additionally, vegetation changes are centered on the watersheds and expand to the surrounding area, with a clear increase in vegetation in the Kumukuri Basin. Areas with a vegetation Hurst index of <0.5 account for 63.27% of the study area, and the areas with a continuous decrease were mainly located in the outer contour area of the Tarim River and Kumu Kuri Basins. (3) There are obvious spatial differences in the correlation between EVI and temperature and precipitation elements. The proportion of areas with positive correlation with temperature within the study area is 64.67%. EVI tends to be consistent with the direction of migration of the center of gravity of the population and GDP, and the areas with positive correlation between vegetation and terrestrial water reserves are mainly distributed in the northern slopes of the Kunlun Mountains, with an area proportion of about 50.513%. The Kumukuli Basin also shows significantly positive correlation. Full article

Mountain glaciers are considered natural indicators of warming and a device for climatic change. In addition, it is also a solid reservoir of freshwater resources. Along with climate change, clarifying the dynamic changes of glacier in the Aksu River Basin (ARB) are important for hydrological processes. The study examined the variations in glacier area, elevation, and their reaction to climate change in the ARB between 1990 and 2022. The glacier melt on the runoff is explored from 2003 to 2020. This investigation utilized Landsat and Sentinal-2 images, ICESat, CryoSat, meteorological and hydrological data. The findings suggest that: (1) The glacier area in the ARB retreated by 309.40 km² (9.37%, 0.29%·a⁻¹) from 1990 to 2022. From 2003 to 2021, the ARB glacier surface elevation retreat rate of 0.38 ± 0.12 m·a⁻¹ (0.32 ± 0.10 m w.e.a⁻¹). Comparison with 2003–2009, the retreat rate is faster from 2010 to 2021. (2) From 1990 to 2022, the Toxkan and the Kumalak River Basin’s glacier area decreases between 61.28 km² (0.28%·a⁻¹) and 248.13 km² (0.30%·a⁻¹). Additionally, the rate of glacier surface elevation declined by −0.34 ± 0.11 m·a⁻¹, −0.42 ± 0.14 m·a⁻¹ from 2003 to 2021. (3) The mass balance sensitivities to cold season precipitation and ablation-phase accumulated temperatures are +0.27 ± 0.08 m w.e.a⁻¹(10%)⁻¹ and −0.33 ± 0.10 m w.e.a⁻¹ °C⁻¹, respectively. The mass loss is (962.55 ± 0.57) × 10⁶ m³ w.e.a⁻¹, (1087.50 ± 0.68) × 10⁶ m³ w.e.a⁻¹ during 2003–2009, 2010–2021 respectively. Warmer ablation-phase accumulated temperatures dominate glacier retreat in the ARB. (4) Glacier meltwater accounted for 34.57% and 41.56% of the Aksu River’s runoff during the ablation-phase of 2003–2009 and 2010–2020, respectively. The research has important implications for maintaining the stability of water resource systems based on glacier meltwater. Full article

The Tarim River Basin, China’s largest inland river basin, is renowned for its ecological fragility characterized by concurrent greening and desertification processes. Soil wind erosion emerges as a critical factor impacting the natural ecosystem of this region. This study employs a soil wind erosion model tailored to cultivated land, grassland, and desert terrains to analyze the multitemporal characteristics of and spatial variations in soil wind erosion across nine subbasins within the Tarim River Basin, utilizing observed data from 2010, 2015, and 2018. Additionally, this study investigates the influence of various factors, particularly wind speed, on the soil wind erosion dynamics. Following established standards of soil erosion classification, the intensity levels of soil erosion are assessed for each calculation grid within the study area alongside an analysis of the environmental factors influencing soil erosion. Findings indicate that approximately 38.79% of the total study area experiences soil wind erosion, with the Qarqan River Basin exhibiting the highest erosion modulus and the Aksu River Basin registering the lowest. Light and moderate erosion predominates in the Tarim River Basin, with an overall decreasing trend observed over the study period. Notably, the Qiemo River Basin, Dina River Basin, and Kaidu Kongque River Basin display relatively higher proportions of eroded area compared to their total subbasin area. Furthermore, this study underscores the substantial influence of the annual average wind speed on soil erosion within the study area, advocating for prioritizing soil and water conservation programs, particularly in the downstream regions of the Tarim River Basin, to mitigate future environmental degradation. Full article

The quality of drinking water is crucial for human health and the sustainable development of societies. The Aksu River Basin, a typical inland river system, has areas where groundwater arsenic levels exceed safe drinking water standards (i.e., arsenic concentrations greater than 10 μg/L). Identifying the causes of high arsenic levels in the basin’s groundwater requires further study. Analyzing the hydrogeochemical composition of the Aksu River basin helps us to understand the spatial distribution of groundwater environments and locate areas with dangerously high arsenic levels. In this research, we collected 196 groundwater samples from along the river. Out of these, 38 samples had arsenic levels above 10 μg/L, which represents 19.4% of the total samples collected. By examining the slope changes in the cumulative frequency curves of major ion ratios and employing geostatistics (specifically, the Kriging interpolation), and taking into account the environmental characteristics of the entire basin, we divided the study area into five sub-regions (Zone I through Zone V). The geostatistical analysis showed a significant spatial variability in groundwater arsenic levels, with a clear spatial correlation. Our findings demonstrate that arsenic concentrations in the Aksu River basin’s groundwater vary widely, with Zones II and III—mainly located in the northeastern part of the basin and in Awat County—being hotspots for high-arsenic water. Factors such as a weak reducing environment, intense evaporation, strong cation exchange, and the low-permeability recharge of surface water contribute to the accumulation of arsenic in the basin’s groundwater. The results of this study are vital for assessing the risk of arsenic contamination in groundwater in similar basins and for identifying critical areas for further investigation and research. Full article

In arid areas, vegetation is the basis for maintaining the virtuous cycle of ecosystems, while water resources are the key factor restricting the survival of vegetation communities. The balance between water resources and vegetation is related to the sustainable development of ecological benefits and economic benefits in arid areas. Although research on the carrying potential of vegetation in arid areas has been emphasized, there is still a lack of spatial analysis of different vegetation types over large areas. Therefore, this study takes precipitation as the basic source of water resources, calculates the amount of available water resources in the basin from the available effective precipitation and available irrigation water, and it analyzes the spatial distribution of forest and grass vegetation types under the water resources constraint, combined with the ecological water demand of different vegetation types and based on the principle of “Water to determine the Vegetation”. The results showed that the ecological water demand of each vegetation type was as follows: Forest > Shrub Vegetation > Grassland Vegetation > Desert Vegetation. The range of comprehensive available water resources of vegetation was from 0 to 221.71 mm, which decreased with the altitude gradient. Then, the spatial distribution pattern of vegetation types constrained by the water resources in the Aksu River Basin showed a striped distribution from north to south, with shrub vegetation in the high-altitude mountainous area, grassland vegetation in the low-altitude area, and desert vegetation in the desert plain area, respectively, accounting for 29.05%, 10.74%, and 53.45% of the total basin. This research approach provides a scientific basis for the planning of forest and grass vegetation construction in arid regions. Full article

Thoroughly investigating the evolution of groundwater circulation and its controlling mechanism in the Aksu River Basin, where human activities are intensifying and the groundwater environment is increasingly deteriorating, is highly urgent and important for promoting the theory, development and implementation of groundwater flow systems (GFSs) and protecting groundwater resources. Based on a detailed analysis of the sediment grain size distribution, chronology, electrofacies, glacial sedimentary sequence, palaeoclimate indicators and existing groundwater age, this paper systematically reconstructs the palaeosedimentary environment of the basin-scale aquifer system in the study area and scientifically reveals the evolutionary pattern and formation mechanism of the GFS. The results showed that the later period of the late Pleistocene experienced a rapid downcutting erosional event caused by tectonic uplift, and the sedimentary environment transitioned from a dry–cold deep downcutting environment in the Last Glacial Maximum (LGM) to a coarse-grained fast-filling fluvial facies sedimentary environment in the Last Glacial Deglaciation (LDP) as the temperature rose; then, it shifted to an environment of fine-grained stable alternating accumulation of fluvial facies and lacustrine facies that was dominated by the warm and arid conditions of the Holocene megathermal period (HMP); this process changed the previous river base level via erosion, glacier elongation or shortening and river level, thus resulting in a complex coupling relationship between the palaeosedimentary environment, palaeoclimate and basin GFS. Furthermore, the existing GFS pattern in the basin exhibits a vertically unconformable groundwater age distribution, which indicates that it is the outcome of the complex superposition of groundwater flow controlled by the palaeosedimentary environment in different periods. Therefore, neotectonic movement and climate fluctuation have jointly acted on the variation in the river level, resulting in the “seesaw” effect, thereby fundamentally controlling the strength of the driving force of groundwater and resulting in the gradual evolution of the GFS from the fully developed regional GFS pattern during the LGM to the current multihierarchy nested GFS pattern. Full article

The Aksu River, a quintessential inland river, exhibits elevated arsenic (As) concentrations in certain sections of its natural waters. Further investigation is necessary to determine the role of surface water and groundwater (SW-GW) exchanges in contributing to these high As concentrations. Both surface water and groundwater constitute crucial components of the basin water cycle, and the interaction between the two has been a central focus in basin water cycle research. In this study, a total of 59 groundwater samples and 41 surface water samples were collected along the river’s course within the basin. Among the groundwater samples, 18.64% exceeded the permissible drinking limit for As concentrations (10 μg/L), while 39.02% of the surface water samples exceeded this threshold. The water bodies in the Aksu River Basin are mildly alkaline, with total dissolved solids (TDSs) in surface water significantly surpassing those in groundwater. The chemical compositions of surface water and groundwater are strikingly similar, with the predominant anions being chloride (Cl⁻) and sulfate (SO₄²⁻) and the principal cations being sodium (Na⁺). The dissolution of silicate and carbonate minerals primarily influences the water chemistry characteristics of surface water and groundwater in the Aksu River Basin, followed by the dissolution of salt rocks. Human activities also play a major role in affecting the river’s water quality. The distribution of groundwater with elevated As content is entirely encompassed within the spatial distribution of surface water. Groundwater–surface water exchange plays a vital role in As enrichment in surface water. Full article

To achieve high-quality sustainable development in arid areas based on the concept of ecological civilization, it is necessary to deeply study the territorial spatial structure characteristics. Taking the Aksu River Basin, an important ecological security barrier in northwest China, as an example, this paper follows the research idea of “feature analysis-suitability evaluation-conflict identification analysis-optimization” and constructs a comprehensive model based on the AHP-entropy weight comprehensive evaluation method, ArcGIS spatial identification analysis, variance coefficient-TOPSIS method, and NRCA. A comprehensive model based on the AHP-entropy power integrated evaluation method, ArcGIS spatial identification analysis, variance coefficient-TOPSIS method, and NRCA was constructed to guide the optimization of the territorial spatial layout by exploring the characteristics of territorial spatial pattern, the suitability of territorial spatial development, the identification of territorial spatial conflicts, and the efficiency and functional advantage of territorial spatial utilization in the study area. The results show that: (1) The spatial type of territorial space in the Aksu River Basin from 2000 to 2020 is dominated by ecological space, agricultural space, and urban space, and the three spatial boundaries are irregularly interlaced. (2) The spatial utilization conflict pattern of the Aksu River Basin has formed, and the general conflict area is overgrowing. (3) The overall efficiency of territorial utilization in the Aksu River Basin is low, with significant differences among county administrative units. (4) After optimization, the three types of space in the watershed are adjusted and refined into six functional areas: basic farmland protection area, rural development area, ecological protection red line area, ecological control area, urban development area, and industrial supporting construction area. Full article

While rock glaciers (RGs) are widespread in the Zhetysu Alatau mountain range of Tien Shan (Kazakhstan), they have not yet been systematically investigated. In this study, we present the first rock glacier inventory of this region containing 256 rock glaciers with quantitative information about their locations, geomorphic parameters, and downslope velocities, as established using a method that combines SAR interferometry and optical images from Google Earth. Our inventory shows that most of the RGs are talus-derived (61%). The maximum downslope velocity of the active rock glaciers (ARGs) was 252 mm yr⁻¹. The average lower height of rock glaciers in this part of the Zhetysu Alatau was 3036 m above sea level (ASL). The largest area of rock glaciers was located between 2800 and 3400 m ASL and covered almost 86% of the total area. Most rock glaciers had a northern (northern, northeastern, and northwestern) orientation, which indicated the important role of solar insolation in their formation and preservation. Full article

Timely understanding and quantitative analysis of the changing trend in natural ecosystems in arid and semi-arid areas and their response to the ecological water supply process are of great significance for maintaining the health of oasis ecosystems. Taking the Eichmann Lake wetland of the Aksu River Basin in Xinjiang as the research area, the temporal-spatial distribution characteristics of the lake and the response of ecological water in recent years were studied based on remote sensing images and monitoring data. The results show that: (1) The water surface area of Eichmann Lake is shrinking, from 61.57 km² in 1996 to 27.76 km² in 2020. The changes in water surface area have experienced three stages: rapid decline, slow decline, and slow recovery. After the ecological water supply, the water surface area has obvious seasonal changes with hysteresis; (2) In areas with a low average water level, the ecological water supply has a significant impact on the groundwater level. The higher the water supply is, the higher the groundwater level will be. There is a significant lag effect between the change in the groundwater level and the response of the ecological water supply, which is 1–2 months; (3) The response characteristics of different natural vegetation to the ecological water supply were different in interannual, seasonal, and spatial contexts. The response of Populus euphratica to the ecological water supply is obvious, and its growth is the best within the range of 100–500 m from the water supply outlet. This research can provide the basis for the rational allocation of the Aksu River Basin’s water resources, and also act as a valuable reference for the restoration and reconstruction of surrounding vegetation in the Aksu River irrigation area. Full article