Search Results (215)

In ecologically fragile and geomorphologically complex mountainous regions, ensuring a smooth transition from poverty alleviation to multidimensional sustainable rural development remains a key issue in regional governance. Focusing on the Qinba Mountains, a typical former contiguous poverty-stricken region in China covering 18 prefecture-level cities in six provinces, this study uses 2009–2023 prefecture-level panel data to examine the spatiotemporal evolution and driving mechanisms of coordinated rural revitalization. An integrated framework of “multi-dimensional evaluation–spatiotemporal tracking–attribution diagnosis” is developed by combining the improved AHP–entropy-weight TOPSIS method, the Coupling Coordination Degree (CCD) model, spatial Markov chains, spatial autocorrelation, and the Geodetector. The results show pronounced subsystem asynchrony. Livelihood and Well-being Security (U5) improves steadily, while Level of Industrial Development (U1), Civic Virtues and Cultural Vibrancy (U3), and Rural Governance (U4) also rise but with clear spatial differentiation; by contrast, Quality of Human Settlements (U2) fluctuates in stages under ecological fragility. Overall, the coupling coordination level advances from the Verge of Imbalance to Intermediate Coordination, yet the regional pattern remains uneven, with eastern basin cities leading and western deep mountainous cities lagging. State transitions display both policy responsiveness and path dependence: the probability of retaining the original state ranges from 50.0% to 90.5%; low-level neighborhoods reduce the upward transition probability to 25%, whereas medium-to-high-level neighborhoods raise the upward transition probability of low-level cities from 36.36% to 53.33%. Spatial dependence is also evident, with Global Moran’s I increasing, with fluctuations, from 0.331 in 2009 to 0.536 in 2023; high-value clusters extend along the Guanzhong Plain–Han River Valley corridor, while low-value clusters remain relatively locked in mountainous border areas. Driving mechanisms show clear stage-wise succession. At the single-factor level, the explanatory power of Road Network Density (F6) declines from 0.639 to 0.287, whereas Terrain Relief Amplitude (F1) becomes the dominant background constraint in the later stage (q = 0.772). Multi-factor interactions are generally enhanced. In particular, the traditional infrastructure-led pathway weakens markedly, with F1 ∩ F6 = 0.055 in 2023, while the interaction between terrain and consumer market vitality becomes dominant, with F1 ∩ F7 = 0.987 in 2023. On this basis, three major pathways are identified: government fiscal intervention and transportation accessibility improvement, capital agglomeration and market demand stimulation, and human–earth system adaptation and ecological value realization. These findings provide quantitative evidence for breaking spatial lock-in and improving cross-regional resource allocation in ecologically constrained mountainous regions. Full article

The Xingqi (行气, breath circulation) pattern bronze mirrors of the Song Dynasty (960–1279 CE) represent a distinctive category of Daoist material culture in southern China. Despite their unique iconography, systematic research on their functions and religious significance has been lacking. This study examines sixteen Xingqi pattern bronze mirrors through iconographic analysis and textual research, integrating evidence from surviving Daoist scriptures and ritual manuals. Two primary types are identified: the “Tortoise-Swallowing and Crane-Breathing Style” and the “Sun and Moon Observing Style”. The former depicts practitioners imitating the breathing techniques of tortoises and cranes, while the latter shows figures gazing upward to ingest the essences of the sun and moon. Both motifs continue earlier health preservation traditions from the Pre-Qin (221–207 BCE) through Han dynasties, adapted within the Northern and Southern Song context. These mirrors were specifically used by Daoists along the middle Yangtze River for inner alchemy cultivation, particularly in visualized Cunsi (存思, contemplation practices). They were predominantly passed down through generations rather than buried, explaining their scarcity in archaeological contexts. These artifacts illuminate how Song Daoism translated abstract philosophical concepts into tangible, operable practices through material imagery. They provide new physical evidence for understanding historical Daoist cultivation methods and the materialization of religious experience. Full article

As the largest tributary of the Yangtze River and a core area of the Middle Route of the South-to-North Water Diversion Project, the Han River Basin holds significant ecological importance regarding the impacts of land use and water environment changes on aquatic ecosystems. Existing studies have mostly focused on local reaches of the upper or middle–lower Han River, and systematic investigations into the associations between macroinvertebrate communities and environmental factors at the entire basin scale remain scarce. The niche characteristics and environmental drivers of macroinvertebrate community structure in the Han River Basin, China, were evaluated using a variety of diversity metrics and statistical methods. The results showed that: (1) A total of 91 macroinvertebrate taxa were identified during 2022–2023, with Insecta as the dominant group. Species richness in the upstream reaches increased in 2023, and the degree of differentiation between the upstream and the middle–lower reaches was markedly weaker than that in 2022. (2) Significant interannual differences in macroinvertebrate community structure were detected (PERMANOVA, p < 0.05), and taxa such as Polypedilum sp., Orthocladius sp., and Gammaridae collectively accounted for 35.6% of the dissimilarity among communities. (3) The overall niche breadth of dominant taxa was relatively low, whereas niche overlap decreased significantly in 2023, indicating a community niche pattern characterized by “low competition–high differentiation”. (4) Total phosphorus (TP) and total nitrogen (TN) were the core water environmental factors driving changes in community structure, while forested land was the key land use factor, and their synergistic effects jointly regulated the composition and diversity of macroinvertebrate communities. Full article

Distinguishing the hydrological impacts of anthropogenic groundwater withdrawal from natural climate variability is a critical yet complex challenge in sustainable water resource management. This study quantitatively evaluated the watershed-scale hydrological response to the increased groundwater abstraction in the Han River basin (35,770 km²) of South Korea using the Soil and Water Assessment Tool (SWAT). Groundwater use datasets for the 1970s and 2010s were constructed using groundwater statistical yearbooks. By applying the groundwater use datasets under 2010s weather conditions, we effectively isolated the specific effects of human usage. The results indicated that a rise in the annual groundwater abstraction from 9.6 to 22.3 million m³ reduced the average streamflow by 6.59%. The baseflow and groundwater recharge were identified as the most sensitive components, decreasing by 20.7% and 20.8%, respectively. Notably, intensive summer withdrawal (53% of the annual total) depleted aquifer storage, directly exacerbating streamflow reductions during the autumn and winter seasons. A flow duration analysis further confirmed that the duration of the dry season—defined by the flow exceeded for 275 days (Q₂₇₅)—extended by 13 days, as the exceedance duration for the specific flow duration shifted from Q₂₇₅ to Q₂₆₃. These findings highlighted that excessive groundwater withdrawal compromises seasonal hydrological stability, necessitating integrated management strategies to secure the streamflow during critical dry periods. Full article

Evapotranspiration (ET) data products has greatly facilitated the hydrological research in complex basins, and various ET datasets have been produced and applied. The applicability and reliability of ET dataset is significant for regional studies. Therefore, this study compared ET datasets from multisource remote sensing (GLEAM, MOD16, GLASS, PML-V2, Han, Chen and Ma), machine learning (Jung) and reanalysis products (ERA5-Land, MERRA2) for the Yarlung Zangbo River basin (YZB). ET was estimated using the terrestrial water balance (TWB) and was taken as baseline for comparisons of different ET datasets in terms of spatial distribution and temporal variation. Results indicate that (1) the TWB-based ET estimates are rational with acceptable uncertainties; (2) the multi-source ET datasets exhibit good correlations with TWB-ET across the entire basin (r = 0.78–0.90) in term of annual variation, with GLEAM-ET performing the best (r = 0.88, RMSE = 14.24 mm, Rbias = 18.55%); (3) Spatially, PML-ET and Ma-ET show higher consistency with TWB-ET, and temporally, MOD16-ET and GLASS-ET better capture the changing trend; (4) A comprehensive evaluation using the linear weighted method reveals that GLASS-ET and GLEAM-ET perform relatively well in all aspects and are reliable datasets for ET research in the YZB. These findings provide a scientific basis for ET estimation and data selection in the YZB, offering important references for ET analysis and hydrological research. Full article

This study compares and evaluates the performance of a statistical model, Multiple Linear Regression (MLR), and a deep learning model, Long Short-Term Memory (LSTM), for predicting monthly mean temperature in the Han River Basin, South Korea. Predictor variables were dynamically selected based on lagged correlation analysis between climate indices and temperature over the past 40 years, identifying the top ten variables with the highest correlations for lag times ranging from 1 to 18 months. The MLR model was developed through stepwise regression with cross-validation, while the LSTM model was constructed using an 18-month input sequence to capture temporal dependencies in the data. Model performance was evaluated using percent bias (PBIAS), Nash–Sutcliffe efficiency (NSE), Pearson’s correlation coefficient (r), and tercile-based probability metrics. Both models reproduced the seasonal variability of monthly temperature with high accuracy (NSE > 0.97, r > 0.98). The LSTM model showed slightly higher predictive skill in several periods but also exhibited larger prediction variance, reflecting the sensitivity of nonlinear architectures to variations in predictor–response relationships. In contrast, the MLR model demonstrated more stable predictive behavior with narrower uncertainty bounds, particularly under low signal-to-noise conditions, owing to its structural simplicity. These findings indicate that the two approaches are complementary; the LSTM model better captures nonlinear temporal dynamics, while the MLR model provides interpretability and robustness. Future work will explore advanced hybrid architectures such as CNN–LSTM and Transformer-based models, as well as multi-model ensemble methods, to further enhance the accuracy and reliability of medium-range temperature prediction. Full article

The endangered freshwater fish Gobiobotia brevibarba is endemic to Korea and threatened by habitat disturbance in major river systems. We investigated four wild populations from the Han River basin (IJR, BHR, NHR) and the Geum River basin (GR) using eleven microsatellite loci to assess genetic diversity, population structure, and contemporary gene flow. All populations showed relatively high genetic diversity (H_O = 0.709–0.800, H_E = 0.707–0.803) and no evidence of inbreeding, although bottleneck signals under the infinite allele mutation model were detected in IJR and BHR. Contemporary effective population size was large in IJR (N_e = 2463) and moderate in NHR (N_e = 467), whereas estimates for BHR and GR were imprecise. Genetic differentiation was very low within the Han River basin (F_ST = 0.009–0.027) but weak and significant between Han and Geum (F_ST = 0.085–0.096), and clustering analyses (STRUCTURE, DAPC, find.cluster) consistently supported K = 2, separating Han from Geum River. Gene flow analyses indicated extremely limited interbasin gene flow (<4%) but asymmetric contemporary migration from BHR into both IJR and NHR; all other migration rates were similarly low. These results show that G. brevibarba currently maintains high genetic diversity and two basin-level genetic clusters, underscoring the need to manage Han and Geum River populations as separate units and conserve riffle habitats and longitudinal connectivity. Full article

High-resolution in situ field measurements capturing seasonal 3D mixing dynamics at river confluences are scarce, yet this understanding is essential for effective water-quality management and pollutant-transport prediction in river–lake systems. To address this gap, this study investigates the confluence of the North and South Han Rivers in the Paldang Reservoir. We introduce and apply a novel mixing proximity index (MPI) to quantify the degree of mixing and water-mass origin based on 3D electrical conductivity and temperature data. Seasonal field campaigns, conducted with an acoustic Doppler current profiler and multi-parameter sensors, revealed distinct hydrodynamic behaviors: strong summer stratification suppressed vertical mixing; winter momentum asymmetry induced persistent flow separation despite minimal temperature differences; and spring conditions fostered rapid mixing, barring some residual unmixed deep layers. The MPI effectively delineated shear layers and identified unmixed water zones, providing an enhanced understanding of mixing dynamics beyond the capabilities of traditional tracer- or statistics-based metrics. These findings highlight the combined influence of density differences, tributary momentum, and dam operations on confluence mixing, offering practical insights for water-resource management and improving 3D hydrodynamic model validation. Full article

This study systematically investigates settlement sites that record living patterns of ancient humans, aiming to reveal the interactive mechanisms of human–environment relationships. The core issues of landscape archeology research are the surface spatial structure, human spatial cognition, and social practice activities. This article takes the Han Dynasty settlement site in Sanyangzhuang, Neihuang County, Anyang City, Henan Province, as a typical case. It comprehensively uses ArcGIS 10.8 spatial analysis and remote sensing image interpretation techniques to construct spatial distribution models of elevation, slope, and aspect in the study area, and analyzes the process of the Yellow River’s ancient course changes. A regional historical geographic information system was constructed by integrating multiple data sources, including archeological excavation reports, excavated artifacts, and historical documents. At the same time, the sequences of temperature and dry–wet index changes in the study area during the Qin and Han dynasties were quantitatively reconstructed, and a climate evolution map for this period was created based on ancient climate proxy indicators. Drawing on three dimensions of settlement morphology, architectural spatial organization, and agricultural technology systems, this paper provides a deep analysis of the site’s spatial cognitive logic and the ecological wisdom it embodies. The results show the following: (1) The Sanyangzhuang Han Dynasty settlement site reflects the efficient utilization strategy and environmental adaptation mechanism of ancient settlements for land resources, presenting typical scattered characteristics. Its formation mechanism is closely related to the evolution of social systems in the Western Han Dynasty. (2) In terms of site selection, settlements consider practicality and ceremony, which can not only meet basic living needs, but also divide internal functional zones based on the meaning implied by the orientation of the constellations. (3) The widespread use of iron farming tools has promoted the innovation of cultivation techniques, and the implementation of the substitution method has formed an ecological regulation system to cope with seasonal climate change while ensuring agricultural yield. The above results comprehensively reflect three types of ecological wisdom: “ecological adaptation wisdom of integrating homestead and farmland”, “spatial cognitive wisdom of analogy, heaven, law, and earth”, and “agricultural technology wisdom adapted to the times”. This study not only deepens our understanding of the cultural value of the Han Dynasty settlement site in Sanyangzhuang, but also provides a new theoretical perspective, an important paradigm reference, and a methodological reference for the study of ancient settlement ecological wisdom. Full article

Human activities have altered rivers worldwide, but how their combined effects shape fish assemblages remains unclear. We therefore surveyed fish and habitats seasonally along the middle and lower reaches of the Han River, China, during 2022, specifically in June–August (wet season) and October–November (dry season). This study analyzed the spatial distribution pattern of fish diversity, explored the effects of natural factors (e.g., hydrology, water quality) and human stressors (e.g., dam, land use) on the spatial pattern of fish diversity, and identified the key driving factors. Cluster analysis and Non-metric Multidimensional Scaling (NMDS) showed that the fish communities could be divided into three groups: the Danjiangkou reservoir area (DRA), the middle reaches (MR), and the lower reaches (LR). For α-diversity, the LR had the highest value, followed by the DRA, with the MR being the lowest. For β-diversity, the MR had the highest value, followed by the LR, with the DRA being the lowest. Random Forest model showed that fish diversity was mainly affected by natural factors; among these factors, the key drivers of α-diversity were hydrological factors such as the water level (3.56–5.97%) and river width (4.53–4.69%), while for β-diversity, the key drivers were water quality factors, including the dissolved oxygen (10.08–12.36%), total nitrogen (6.49–9.31%), and chlorophyll a (8.26–8.40%). Structural Equation Modeling further revealed that natural factors affected β-diversity mainly through direct pathways, while human stressors affected β-diversity mainly through indirect pathways. The results revealed the differential roles of natural factors and human stressors in driving the patterns of fish α-diversity and β-diversity in human-disturbed rivers, which will provide a scientific basis for the conservation of fish diversity in the Han River. Full article

In dam operations, sudden discharges during extreme rainfall events can pose severe flood risks to downstream communities. This study developed a dam discharge-based river water level forecasting model using a data-driven deep learning approach, long short-term memory (LSTM). To enhance predictive performance, physics-based HEC-RAS simulation outputs, including extreme events, were incorporated as additional inputs. The Seomjin River Basin in South Korea, which recently experienced severe flooding, was selected as the study area. Hydrological data from 2010 to 2023 were utilized, with 2023 reserved for model testing. Forecasts were generated for four lead times (3, 6, 12, and 24 h), consistent with the operational flood forecasting system of the Ministry of Environment, South Korea. Using only observed data, the model achieved high accuracy at upstream sites, such as Imsil-gun (Iljung-ri, R² = 0.92, RMSE = 0.27 m) and Gokseong (Geumgok Bridge, R² = 0.91, RMSE = 0.35 m), for a 6-h lead time. However, performance was lower at Gurye-gun (Songjeong-ri, R² = 0.72, RMSE = 1.48 m) due to the complex influence of two dams. Incorporating enhanced inputs significantly improved predictions at Gurye-gun (R² = 0.91, RMSE = 1.17 m at 3 h). Overall, models using only observed data performed better at upstream sites, while enhanced inputs were more effective in downstream or multi-dam regions. The 6-h lead time yielded the highest overall accuracy, highlighting the potential of this approach to improve real-time dam operations and flood risk management. Full article

Taste and odor (T&O) compounds in freshwater are frequently produced by certain cyanobacteria; however, their occurrence remains difficult to predict. This study examined the temporal and spatial variations in the mibC gene, which encodes a critical enzyme in the biosynthesis of 2-methylisoborneol (2-MIB), by analyzing environmental DNA (eDNA) and RNA (eRNA) in the North Han River, Republic of Korea, from July 2019 to October 2021. Surface water was sampled at twelve sites and analyzed for mibC DNA copy number, RNA expression, cyanobacterial cell density, and 2-MIB concentration using quantitative PCR (qPCR), microscopy, and gas chromatography–mass spectrometry (GC–MS). The mibC gene was present throughout the year, exhibiting peaks from late summer to early winter; higher concentrations typically initiated upstream and subsequently moved downstream. RNA expression was elevated from summer to autumn, rapidly declined following heavy rainfall, and reliably preceded increases in 2-MIB concentrations by 2–4 weeks. RNA levels were strongly correlated with 2-MIB concentrations (r = 0.879, p < 0.001) but showed only a moderate association with Pseudanabaena cell density, whereas DNA demonstrated weaker correlations. More than 95% of total 2-MIB was dissolved, limiting the ability to directly estimate concentrations from eRNA data alone. The results indicate that eRNA monitoring is an effective early warning tool for T&O events. In addition, combining eDNA and eRNA analyses enables a more accurate evaluation of T&O-producing cyanobacteria, presenting practical benefits for proactive management of drinking water. Full article

The presence and accumulation of microplastics (MPs) in riverine waters have been widely documented. The sustained operation of cascade reservoirs has altered the retention characteristics of MPs in the Han River basin. In this study, the composition, sources, and ecological risks of MPs in the water column and sediments of the Han River mainstream across different periods were investigated. Results showed that the MP abundances in the water column and sediments were higher during the flood season than in the non-flood season. Additionally, MPs in the water column exhibited an increasing trend along the operational sequence of cascade reservoirs. During the flood season, polyamide (PA), polyethylene (PE), and polypropylene (PP) were the dominant MP types in the water column, while polycarbonate (PC) and PP prevailed in sediments. In the non-flood season, polyethylene terephthalate (PET) was the dominant MP type in the water column, whereas PC and PET dominated in sediments. Overall, the distribution characteristics of MPs conformed to the “upstream input-reservoir accumulation-downstream output” pattern. The pollution risk of MPs in both the water column and sediments ranged from low to moderate. These findings provide a basis for exploring the impacts of cascade reservoir operation on the characteristics of MP in water and sediments. Future research will focus on migration mechanisms of MP under the joint operation of cascade reservoirs. Full article

Watershed weathering provides a critical pathway for understanding the feedback mechanisms between continental rock chemical weathering and global climate change. As the longest tributary of the Yangtze River, the Han River plays a crucial role, where samples were collected from the mainstem and tributaries in spring, summer, and autumn to analyze major ion compositions and calculate chemical weathering rates using graphical methods and a forward model. Results show carbonate weathering dominated solute sources (75.7%), followed by silicates (14.8%), with minimal atmospheric and anthropogenic inputs. Spatially, carbonate weathering rate (CWR) and CO₂ consumption rate (ΦCO_2car) increase downstream with lithological variations, while silicate weathering rate (SWR) and CO₂ consumption rate (ΦCO_2sil) exhibit the opposite trend. Basin-wide averages were 9.4 ± 1.2 t/km²/yr (CWR) and 1.3 ± 0.3 t/km²/yr (SWR), with CO₂ consumption rates of 262.6 × 10³ and 55.5 × 10³ mol/km²/yr for carbonates and silicates, respectively. Seasonally, CWR and ΦCO_2car peaked in summer, while SWR and ΦCO_2sil were lower in summer than in spring and autumn. This seasonal pattern suggests that cooler temperatures limit weathering in spring and autumn, while increased summer runoff favors carbonate dissolution. The findings highlight the need for seasonal sampling to accurately assess weathering rates and CO₂ drawdown. Full article

The lacustrine horizon (thickness of 8.75 cm thick) of the Qin and Han dynasties (221 BC–220 AD) was determined based on AMS-¹⁴C analysis conducted by the Beta Analytic Radiocarbon Dating Laboratory on the Dishaogouwan section (37°43′ N, 108°31′ E) in the Salawusu River Basin, Mu Us Desert, located in the temperate zone of China. The identification results of the ostracod and charophyta fossils from the four samples at this horizon show the following results: 1. All the samples contain 458 ostracod fossil valves, belonging to six genera and eight species. Their quantity (valves) and percentage, in descending order of abundance, are Candoniella albicans (Brady), 255/55.68%, Ilyocypris bradyi Sars, 73/15.94%, Eucypris inflata Sars, 46/10.04%, Cyclocypris serena Koch, 26/5.68%, Candona kirgizica Mandelstam, 18/3.93%, Ilyocypris biplicata (Koch), 17/3.71%, Candoniella mirabilis Schneider14/3.06% and Leucocytherella sinensis Huang, 6/1.31%. 2. All the samples contain 99 fossil charophyte gyrogonites, belonging to one genera and four species. In terms of quantity/percentage, the Chara sp. is the most abundant, with 41 pieces (41.41%), followed by Chara braunii Gemlin, with 26 pieces (26.26%); Chara leptosperma Braun and Chara canescens Loiseleur account for 19 pieces (19.19%) and 13 pieces (13.13%), respectively. Based on the analysis of the ecological environment of the existing species of these ostracods and charophytes, combined with the fossilized Ilyocypris brady, Ilyocypris biplicata, and Gyraulus convexiusculus Hutton found in all the samples—which indicate very warm, even subtropical climates then—it can be concluded that during the Qin and Han Dynasties, the Salawusu River Basin was primarily characterized by a freshwater lake environment under a warm climate, with the average annual temperature and precipitation in this area approximately 2.1 °C and 100 mm higher than they are currently. The prevailing East Asian summer monsoon pushed the warm temperate climate at least 110 km northwestward from this basin. During this period, there were at least four episodes of brief subtropical climate fluctuations, occurring approximately every 110 years. Full article