Search Results (46)

Desertification is a serious environmental challenge in regions with desert landscapes, such as the Khorezm Oasis in the Republic of Uzbekistan. Low precipitation rates and shortages of irrigation water have driven dynamic changes in desert-related land use and land cover (LULC) classes, threatening environmental and food security. This study aims to assess desertification safety levels in the Khorezm oasis using geospatial technologies to better understand spatiotemporal dynamics and to support sustainable agricultural management. A multi-criteria decision-making (MCDM) approach was used for desertification assessment. Annual mean values of key indicators—land surface temperature, vegetation index, groundwater (GW) depth, wind speed, soil erodibility (K-factor), precipitation, normalized enhanced sand index, maximum air temperature, and LULC classes—were analyzed for the period 2000–2023. The results indicate that the normalized enhanced sand index and LULC classes exert the strongest influence on desertification processes. Areas classified as high to very high desertification hazard are predominantly concentrated in the Republic of Karakalpakstan, covering a total area of 2345.65 km². Ongoing water shortages in the Amu Darya River basin pose a significant risk of further expansion of desertified areas. The findings provide valuable insights for regional land management and desertification mitigation planning. Full article

The prediction of thin-bedded, favorable sand bodies within the Middle-Lower Jurassic braided river delta–lacustrine succession of Block S (Amu Darya Right Bank) is challenging because of strong spatial heterogeneity, deep burial, and limited seismic resolution near the acoustic basement. To address this, we propose an integrated workflow that combines sedimentological characterization with geologically constrained seismic inversion. The study uses core, grain-size data, wireline logs, and 3D seismic surveys. Core–log–seismic integration first delineates three subfacies and nine numbered microfacies (MF1–MF9), with the delta front dominated by underwater distributary channels (MF1), mouth bars (MF2), and interdistributary bays (MF3). Planar microfacies distribution maps and electrofacies boundaries are then used as geological constraints for reservoir prediction. Steerable pyramid enhancement ($K=4$ scales, $N=6$ orientations) improves channel-reflection continuity, and PDF-regularized stochastic optimization inversion ($\lambda =0.8$) is performed to identify thin sand reservoirs. Sand-ratio and GR cutoffs were validated against 412 core–log contacts in five wells. Discretization sensitivity tests confirm stable inversion under 2 ms and 4 ms sampling. The results show that (1) favorable Type I and Type II reservoirs occur preferentially in MF1 and MF2 (average porosities of 12.7% and 10.1%, respectively); (2) vertically, two sand-rich progradational intervals (Lower Member and late Upper Member) are separated by a transgressive mud-prone middle–early Upper Member; and (3) inversion low-impedance anomalies delineate strip-like and lobate channel–mouth-bar sand belts with thickness up to 14 m, consistent with well control. Fault-controlled graben–horst paleotopography influenced sand fairway distribution. The workflow highlights the value of integrating sedimentary microfacies boundaries as geological constraints in seismic inversion for heterogeneous deep clastic gas reservoirs. Full article

To address the pronounced interlayer productivity disparity and uneven reserve utilization during the development of multilayer low-permeability porous carbonate gas reservoirs, the G gas field on the right bank of the Amu Darya River was selected as the study area. Core-parallel physical simulation experiments, orthogonal numerical simulations, and production logging test (PLT) data were integrated to investigate the mechanisms of interlayer interference and its key controlling factors under multilayer commingled production. The results show that interlayer interference is primarily controlled by the permeability contrast and production differential. With increasing permeability contrast, high-permeability layers contribute a larger proportion of total production, whereas the utilization of medium- and low-permeability layers declines, thereby intensifying interlayer interference. Under the same permeability configuration, the interference coefficient increases with increasing production differential. Moreover, compared with the two-layer commingled-production cases, the three-layer system showed a stronger response to pressure-differential variation. When the production differential increased from 1 MPa to 5 MPa, the interference coefficient in the three-layer system increased from 9.84% to 27.83%, indicating more pronounced productivity loss in the medium- and low-permeability layers. Orthogonal numerical simulation indicates that the sensitivity of the main controlling factors follows the order of production differential ≥ permeability ratio > thickness ratio > gas viscosity. PLT data further validate the reliability of the experimental and numerical simulation results. During the development of Well G-22, the XVac layer consistently dominated gas production, whereas the XVm and XVp layers acted as supplementary contributors, indicating a dynamic production pattern in which high-permeability layers are preferentially activated and medium- and low-permeability layers contribute progressively at later stages. These findings demonstrate that permeability heterogeneity is the fundamental cause of interlayer interference, while the production differential serves as an important amplifying factor. This study provides a theoretical basis for zonal production allocation, optimization of the production differential, and stable production management in multilayer low-permeability porous carbonate gas reservoirs. Full article

The VRB represents one of the most important glacierized regions in the upper Amu Darya Basin (UADB), where glacier and snow dynamics play a key role in regional water resources. This study investigates glacier changes in the VRB during 2000–2025 based on multi-source remote sensing and GIS analysis, while long-term climatic variability since 1970 is used to provide background context for regional climate conditions. The results show a significant reduction in glacier area from 4440.9 km² in 2000 to 3955.2 km² in 2025, corresponding to a loss of 485.7 km² (10.94%). The glaciers are mainly distributed on northern and northeastern slopes at elevations between 4000 and 5000 m a.s.l., where climatic conditions favor their preservation. The basin also contains numerous surge-type glaciers, accounting for approximately 60% of all surge-type glaciers in the Pamir region, with advances ranging from 0.4 to 3.6 km. Climatic analysis indicates a warming trend of 0.15–0.31 °C per decade during 1970–2025, accompanied by pronounced seasonal variability in snow cover and gradual decreases in surface albedo associated with increased dust and black carbon concentrations. Glacier thinning is particularly evident in the lower glacier zones, while hydrological analysis shows that glacier and snow meltwater strongly influence river runoff. These results highlight the sensitivity of glaciers in the VRB to climatic and environmental changes and emphasize the importance of continued monitoring and adaptive water resource management in the VRB. Full article

The Aral Sea Basin (ASB), situated in Central Asia, serves as a prime example of a man-made environmental disaster. The practice of irrigation can be traced back to ancient times. However, the substantial water withdrawals that have occurred since the second half of the 20th century appear to have led to the irreversible drying up of the Aral Sea and the disruption of the flow of the Amu Darya and Syr Darya rivers. This study conducts a comprehensive review of satellite data from the past sixty years, drawing upon a selection of peer-reviewed papers available on Scopus. The selection of papers is conducted in accordance with a methodology that is predicated on the combination of keywords. The study focuses on geoscientific aspects, including the atmosphere, water resources, geology, and geological hazards. The primary sensors employed in this study were Terra-MODIS, NOAA-AVHRR, and the Landsat series. It is evident that certain data types, including radar data, US or Soviet archives, and very-high-resolution data such as OrbView-3, have seen minimal utilisation. Despite the restricted application of remote sensing data in publications addressing the ASB, remote sensing data offer a substantial repository for monitoring the desiccation of the Aral Sea, once the fourth largest continental body of water, and for the estimation of its water surface and volume. Nevertheless, the utilisation of remote sensing in publications concerning the Aral region remains limited, with less than 10% of publications employing this method. Sentinel-2 data has been utilised to illustrate the construction of the Qosh Tepa Canal in Afghanistan, a project which has been the subject of significant controversy, with a particular focus on the issue of water leakage. This predicament is indicative of the broader challenges confronting the region with regard to water management in the context of climate change. A comparison of the Aral Sea’s case history is drawn with analogous examples worldwide, including Lake Urmia, the Great Salt Lake, and, arguably more problematically, the Caspian Sea. Full article

Central Asia (CA) faces growing Water–Energy–Food (WEF) Nexus challenges, due to its complex transboundary water management, legacy Soviet-era water infrastructure, and increasing climate and socio-economic pressures. This study presents the development of a System Dynamics Model (SDM) to evaluate WEF interdependencies across the Aral Sea Basin (ASB), including the Amu Darya and Syr Darya river basins and their sub-basins. Different downscaling strategies based on the area, population, or land use have been applied to process open-access databases at the national level in order to match the scope of the study. Climate and socio-economic assumptions were introduced through the integration of already defined Shared Socioeconomic Pathways (SSPs) and Representative Concentration Pathways (RCPs). The resulting SDM incorporates more than 500 variables interacting through mathematical relationships to generate comprehensive outputs to understand the WEF Nexus concerns. The SDM was successfully calibrated and validated across three key dimensions of the WEF Nexus: final water discharge to the Aral Sea (Mean Absolute Error, MAE, <5%), energy balance (MAE = 4.6%), and agricultural water demand (basin-wide MAE = 1.2%). The results underscore the human-driven variability of inflows to the Aral Sea and highlight the critical importance of transboundary coordination to enhance future resilience. Full article

In arid regions, water scarcity necessitates reliance on surface runoff as a vital water source. Studying the impact of climate change on surface runoff can provide a scientific basis for optimizing water use and ensuring water security. This study investigated runoff patterns in the upper-middle Amu Darya River (UADR) from 1960 to 2015. Special emphasis was placed on the effects of climatic factors and the role of major atmospheric circulation indices, such as the Eurasian Zonal Circulation Index (EZI), Niño 3.4, and the Indian Ocean Dipole (IOD). The results show a significant linear decreasing annual trend in runoff at a rate of 2.5 × 10⁸ m³/year, with an abrupt change in 1972. Runoff exhibited periodic characteristics at 8–16 and 32–64 months. At the 8–16-month scale, runoff was primarily influenced by precipitation (PRE), actual evapotranspiration (AET), and snow water equivalent (SWE), and, at the 32–64-month scale, Niño 3.4 guided changes in runoff. In addition, El Niño 3.4 interacted with the EZI and IOD, which, together, influence runoff at the UADR. This study highlights the importance of considering multiple factors and their interactions when predicting runoff variations and developing water resource management strategies in the UADR Basin. The analysis of nonlinear runoff dynamics in conjunction with multiscale climate factors provides a theoretical basis for the management of water, land, and ecosystems in the Amu Darya Basin. Full article

Between the 5th and 8th centuries AD, several (semi-)nomadic populations invaded ancient Tokharistan (Central Asia), introducing political, socio-economic and cultural changes that also affected pottery production. The study of ceramic materials thereby represents a useful tool for shedding light on the transformations related to such historical events. Unfortunately, no systematic research on ceramics from this region and this period has been conducted to date, and the information available mostly concerns the formal characteristics and imprecise relative chronologies. Aiming to contribute to the knowledge of Early Medieval pottery production in the territory north of the Amu Darya, we present a preliminary investigation on tableware and common wares recovered in the settlements of Khosijat Tepe, Shurob Kurgan, Balalyk Tepe and Dabil Kurgan. This paper provides new data on the vessels’ morphological/stylistic characteristics and relative chronologies, allowing their contextualisation and categorisation. In order to explore the manufacturing processes and their provenance (production areas), a multidisciplinary approach that combines WD-XRF, powder XRD and thin-section optical microscopy was carried out, allowing us to determine the chemical, mineralogical and petrographic compositions, respectively. The results suggest that most vessels consist of local/regional products. The choice and processing of the raw materials are broadly similar. However, slight variations are observed among the ceramics from distinct sites, related to the procurement of clayey sediments from different sources. Although a certain degree of morphological and technological continuity regarding the preceding Kushano-Sasanian pottery tradition is attested for some functional categories, new shapes and decorations appear, confirming the introduction of new practices in the region. Full article

For the first time, we have compiled a general list of diatoms for the Zarafshan River consisting of 428 species based on our own research and the literature data. Indicator species for nine water parameters were identified, making up more than 90% of the list. Bioindicators and statistical methods revealed that sections of the river around the city of Samarkand and further in the middle reaches reflect the complexity of the impact of the environment on diatom communities. The surveyed sections of the middle reaches of the river are divided into branches and the dynamics of water parameters and diatom communities are shown from the border with Tajikistan to the confluence of the Zarafshan with the Amu Darya. The indices of organic pollution, S, and toxic impact, WESI, were calculated. They show that there is an increase in salinity and turbidity and a decrease in organic pollution downriver. At the same time, the Navoi section is a source of water acidification. Nutrients and heavy metals, as well as phenol pollution, enter the river from various sources, mainly in the middle reaches of the river. The Zarafshan Nature Reserve in the catchment area of the upper section of the river within Uzbekistan is important for maintaining water quality. Bioindicators show an increase in self-purification, with an increase in the species richness and abundance of diatoms in the middle section of the Zarafshan River. The integrated index of river pollution, RPI, shows that most pollution comes from the northern canal of the river in the middle reaches. A general look at the Zarafshan River catchment basin and the dynamics of the identified water parameters and bioindicator species of diatoms shows that the river ecosystem successfully copes with incoming pollution, including transboundary impacts from Tajikistan. Such a conclusion could not be made based on chemical analysis of the water alone. This allowed us to recommend expanding state monitoring points to the lower section of Karakul while including biological indicators in the observations. Full article

Two freshwater rivers, the Amu Darya and Syr Darya, flow into the Aral Sea, but they began to diminish in the early 1960s, and by the 1980s, the lake had nearly ceased to exist due to excessive water consumption for agriculture and the unsustainable management of water resources from rivers, which transformed the Aral Sea into a hypersaline lake. Despite this, the flora and fauna of the region began to evolve in the high-salinity seabed soil, which has received little attention in studies. In this study, we isolated approximately 1400 bacterial strains from the rhizosphere and phyllosphere of plant species of distinct families. Bacterial isolates were examined for antifungal activities against a range of pathogenic fungi such as Rhizoctonia gossypii, Trichothecium ovalisporum, Fusarium annulatum, F. oxysporum, F. culmorum, F. brachygibbosum, F. tricinctum, F. verticillioides, Alternaria alternata, A. terreus, Aspergillus niger, and As. flavus. Eighty-eight bacterial isolates exhibited varying antagonistic ability against pathogenic fungi. Furthermore, DNA barcoding of isolates using the 16S rRNA gene indicated that most antagonistic bacteria belonged to the Bacillus and Pseudomonas genera. The study also explored the activity of hydrolytic and cell-wall-degrading enzymes produced by antagonistic bacteria. The findings revealed that antagonistic bacteria can be utilized to widely protect seabed plants and plants growing in saline areas against pathogenic fungi, as well as agricultural crops. Full article

In the face of climate change and human activities, Central Asia’s (CA) terminal lake basins (TLBs) are shrinking, leading to deteriorating natural environments and serious soil wind erosion (SWE), which threatens regional socio-economic development, human health, and safety. Limited research on SWE and population exposure risk (PER) in these areas prompted this study, which applied the RWEQ and a PER model to assess the spatiotemporal changes in SWE and PER in TLBs in CA, including the Ili River Basin (IRB), Tarim River Basin (TRB), Syr Darya River Basin (SRB), and Amu Darya River Basin (ARB), from 2000 to 2020. We analyzed the driving factors of SWE and used the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to simulate dust event trajectories. The findings from 2000 to 2020 show a spatial reduction trend in SWE and PER, with primary SWE areas in the Taklamakan Desert, Aral Sea Basin, and Lake Balkhash. Significant PER was observed along the Tarim River, near Lake Balkhash, and in the middle and lower reaches of the ARB and SRB. Over the past 21 years, temporal trends in SWE have occurred across basins, decreasing in the IRB, but increasing in the TRB, SRB, and ARB. Dust movement trajectories indicate that dust from the lower reaches of the SRB and ARB could affect Europe, while dust from the TRB could impact northern China and Japan. Correlations between SWE, NDVI, temperature, and precipitation revealed a negative correlation between precipitation and NDVI, suggesting an inhibitory impact of precipitation and vegetation cover on SWE. SWE also varied significantly under different LUCCs, with increases in cropland, forestland, and desert land, and decreases in grassland and wetland. These insights are vital for understanding SWE and PER in TLBs and offer theoretical support for emergency mitigation in arid regions. Full article

Water resources are scarce and difficult to manage in Kazakhstan, Central Asia (CA). Anthropic activities largely eliminated the Aral Sea. Afghanistan’s large-scale canal construction may eliminate life in the main stream of the Amu Darya River, CA. Kazakhstan’s HYRASIA ONE project, with a EUR 50 billion investment to produce green hydrogen, is targeted to withdraw water from the Caspian Sea. Kazakhstan, CA, requires sustainable programs that integrate both decision-makers’ and people’s behavior. For this paper, the authors investigated groundwater resources for sustainable use, including for consumption, and the potential for natural “white” hydrogen production from underground geological “factories”. Kazakhstan is rich in natural resources, such as iron-rich rocks, minerals, and uranium, which are necessary for serpentinization reactions and radiolysis decay in natural hydrogen production from underground water. Investigations of underground geological “factories” require substantial efforts in field data collection. A chemical analysis of 40 groundwater samples from the 97 wells surveyed and investigated in the T. Ryskulov, Zhambyl, Baizak and Zhualy districts of the Zhambyl region in South Kazakhstan in 2021–2022 was carried out. These samples were compared with previously collected water samples from the years 2020–2021. The compositions of groundwater samples were analyzed, revealing various concentrations of different minerals, natural geological rocks, and anthropogenic materials. South Kazakhstan is rich in natural mineral resources. As a result, mining companies extract resources in the Taraz–Zhanatas–Karatau and the Shu–Novotroitsk industrial areas. The most significant levels of minerals found in water samples were found in the territory of the Talas–Assinsky interfluve, where the main industrial mining enterprises are concentrated and the largest groundwater deposits have been explored. Groundwater compositions have direct connections to geological rocks. The geological rocks are confined to sandstones, siltstones, porphyrites, conglomerates, limestones, and metamorphic rocks. In observation wells, a number of components can be found in high concentrations (mg/L): sulfates—602.0 (MPC 500 mg/L); sodium—436.5 (MPC 200 mg/L); chlorine—465.4 (MPC 350 mg/L); lithium—0.18 (MPC 0.03 mg/L); boron—0.74 (MPC 0.5 mg/L); cadmium—0.002 (MPC 0.001 mg/L); strontium—15, 0 (MPC 7.0 mg/L); and TDS—1970 (MPC 1000). The high mineral contents in the water are natural and comprise minerals from geological sources, including iron-rich rocks, to uranium. Proper groundwater classifications for research investigations are required to separate potable groundwater resources, wells, and areas where underground geological “factories” producing natural “white” hydrogen could potentially be located. Our preliminary investigation results are presented with the aim of creating a large-scale targeted program to improve water sustainability in Kazakhstan, CA. Full article

The archaeological site of Ancient Termez is located in southern Uzbekistan. Despite the arid environment, the city benefited from its strategic position near two rivers, the Amu Darya and the Surkhan Darya. Its significance was mainly related to the expansion of trade routes connecting Eurasia. The city comprises several enclosures that attest long-term human-environment interactions. In order to identify the adaptive dynamics of the settlement models during an extended chronology covering the period from c. 300 BCE to c. 1220 CE (Greco-Bactrian/Yuezhi, Kushan, Kushano-Sasanian, and Islamic periods), a multidisciplinary study has been carried out, which includes: (1) archaeological excavations in several areas of the urban complex; (2) pedestrian surveying inside some enclosures and in the urban periphery; (3) an aerial survey based on high-resolution satellite imagery; (4) AMS dating of charcoal and bone samples; (5) archaeobotanical investigation through anthracological analysis; (6) zooarchaeological studies. The results point to variations in the development of the inhabited spaces, in which abandonment and occupation took place. The zooarchaeological and archaeobotanical data demonstrate the exploitation of natural resources in different environments (i.e., arid areas and irrigated land) and a certain evolution during the period considered. Full article

A material balance equation (MBE) is usually employed to estimate well-controlled dynamic reserves, but a more accurate calculation of these reserves is crucial. For abnormally pressured reservoirs with aquifers, the abnormally pressure and aquifer are difficult to determine, which leads to inaccurate calculations of well-controlled dynamic reserves. In this work, the MBE was established. Then, the correction function and abnormally pressure effect were deduced to determine well-controlled dynamic reserves calculations for weak aquifers and strong aquifers, respectively. For a weak aquifer, a pressure correction was determined to exist at a pressure coefficient of 1.2, and then the correction function was established to calculate the dynamic reserves. For a strong aquifer, the MBE derived by Walsh was employed to calculate the dynamic reserves and water influx. The relationship between the abnormally pressure effect and the dimensionless formation pressure was proposed. Classical, abnormally high-pressured gas reservoirs, Anderson L and Amu Darya, were selected to validate the accuracy and applicability of the newly developed methods. The results show that an abnormally high-pressure effect has a great influence on the dynamic reserves calculation in the early stage and the water influx has a stronger influence on the dynamic reserves calculation in the late stage. Full article

The accurate calculation of sustainable development indicators is essential for the accurate assessment of the Sustainable Development Goals. This study develops a methodology that combines nighttime light indices, population distribution data, and statistics in order to examine changes and key drivers of SDG7 in the Aral Sea Basin from 2000–2020. In this study, the best-performing combination of four light indices and five simulation methods (two linear regression methods and three machine learning methods) was selected to simulate the spatial distribution of GDP in the Aral Sea Basin. The results showed that: (1) The prediction using the XGBoost model with TNL had better performance than other models. (2) From 2000 to 2020, the GDP of the Aral Sea Basin shows an uneven development pattern while growing rapidly (+101.73 billion, +585.5%), with the GDP of the lower Aral Sea and the Amu Darya River gradually concentrating in the middle Aral Sea and Syr Darya River basins, respectively. At the same time, the GDP of the Aral Sea Basin shows a strong negative correlation with the area of water bodies. (3) Although there is a small increase in the score (+6.57) and ranking (+9) of SDG7 for the Aral Sea Basin from 2000 to 2020, it is difficult to achieve SDG7 in 2030. Deepening inter-basin energy cooperation, enhancing investment in renewable energy, and increasing energy intensity is key to achieving SDG7. Full article