Search Results (23)

Anthropogenic activities and climate change have significantly altered runoff generation in the upper Han River basin, posing a challenge to the water supply sustainability for the Middle Route of the South-to-North Water Diversion Project. Land use/cover changes (LUCCs) affect hydrological processes by modifying evapotranspiration, infiltration and soil moisture content. Based on hydro-meteorological data from 1961 to 2023 and LUCC data series from 1985 to 2023, this study aimed to identify the temporal trend in hydro-meteorological variables, to quantify the impacts of underlying land surface and climate factors at different time scales and to clarify the effects of LUCCs and basin greening on the runoff generation process. The results showed that (1) inflow runoff declined at a rate of −1.71 mm/year from 1961 to 2023, with a marked shift around 1985, while potential evapotranspiration increased at a rate of 2.06 mm/year within the same time frame. (2) Annual climate factors accounted for 61.01% of the runoff reduction, while underlying land surface contributed 38.99%. Effective precipitation was the dominant climatic factor during the flood season, whereas potential evapotranspiration had a greater influence during the dry season. (3) From 1985 to 2023, the LUCC changed significantly, mainly manifested by the increasing forest area and decreasing crop land area. The NDVI also showed an upward trend over the years; the actual evapotranspiration increased by 1.163 billion m³ due to the LUCC. This study addresses the climate-driven and human-induced hydrological changes in the Danjiangkou Reservoir and provides an important reference for water resource management. Full article

Acid mine drainage (AMD) generated during the exploitation and utilization of mineral resources poses a severe environmental problem globally within the mining industry. The Xiaomixi Stream in Ziyang County, Shaanxi Province, is a primary tributary of the Han River, which is surrounded by historically concentrated mining areas for stone coal and vanadium ores. Rainwater erosion of abandoned mine tunnels and waste rock piles has led to the leaching of acidic substances and heavy metals, which then enter the Haoping River and its tributaries through surface runoff. This results in acidic water, posing a significant threat to the water quality of the South-to-North Water Diversion Middle Route within the Han River basin. According to this study’s investigation, Xiaomixi’s acidic water exhibits yellow and white precipitates upstream and downstream of the river, respectively. These precipitates stem from the oxidation of iron-bearing minerals and aluminum-bearing minerals. The precipitation process is controlled by factors such as the pH and temperature, exhibiting seasonal variations. Taking the Xiaomixi Stream in Ziyang County, Shaanxi Province, as the study area, this paper conducts field investigations, systematic sampling of water bodies and river sediments, testing for iron and aluminum pollutants in water, and micro-area observations using field emission scanning electron microscopy (FESEM) on sediments, along with analyzing the iron and aluminum content. The deposition is analyzed using handheld X-ray fluorescence (XRF) analyzers, X-ray diffraction (XRD), and visible–near-infrared spectroscopy data, and a geochemical model is established using PHREEQC software. This paper summarizes the migration and transformation mechanisms of iron and aluminum pollutants in acidic water and proposes appropriate prevention and control measures. Full article

To eliminate the noise interference caused by continuous external environmental disturbances on the rotor signals of a maglev gyroscope, this study proposes a noise reduction method that integrates an adaptive particle swarm optimization variational modal decomposition algorithm with a strategy for error compensation of the trend term in reconstructed signals, significantly improving the azimuth measurement accuracy of the gyroscope torque sensor. The optimal parameters for the variational modal decomposition algorithm were determined using the adaptive particle swarm optimization algorithm, allowing for the accurate decomposition of noisy rotor signals. Additionally, using multi-scale permutation entropy as a criterion for discriminant, the signal components were filtered and summed to obtain the denoised reconstructed signal. Furthermore, an empirical mode decomposition algorithm was employed to extract the trend term of the reconstructed signal, which was then used to compensate for the errors in the reconstructed signal, achieving significant noise reduction. On-site experiments were conducted on the high-precision GNSS baseline of the Xianyang Yuan Tunnel in the second phase of the project to divert water from the Han River to the Wei River, where this method was applied to process and analyze multiple sets of rotor signals. The experimental results show that this method effectively suppresses continuous external environmental interference, reducing the average standard deviation of the compensated signals by 46.10% and the average measurement error of the north azimuth by 45.63%. Its noise reduction performance surpasses that of the other four algorithms. Full article

Increasing public health awareness has stressed the significance of the mental and physical benefits of outdoor activities. Government involvement and support for urban redevelopment projects in Korea, such as Seoul Dulle-gil, connected previously disconnected green spaces. Despite the ecological and cultural importance of urban spaces, their impact on residents and tourists and their role in exploring the city’s dynamic remains limited. This study aims to evaluate how green space activities engage in sustainable land management and offer insights into surrounding communities. A quantitative big data research method was employed, analyzing 3995 online blog post reviews using Python code, and sentiment analysis conducted with pandas and KoNLPy’s Okt library. The results indicated that sentiment scores were generally higher in sections located south of the Han River. Among the eight trail courses, courses 6, 3, 4, and 5, located south of the Han River, exhibited higher sentiment scores compared to courses 7, 8, 2, and 1, located north of the Han River, which showed lower satisfaction levels. Among the 16 characteristics influencing visitor satisfaction, the study emphasized the importance of potential space maintenance to enhance trail user safety and community well-being, contributing to sustainable land management. Full article

The Han River Estuary (HRE), Yellow Sea, forms part of the border between South Korea and North Korea, and these two countries are militarily hostile. Since the HRE has quite excellent ecological integrity, the task of preserving it well is emerging as important. Thus, the South Korean Government is attempting to preserve the ecological integrity of the HRE through interstate cooperation. By employing contingent valuation, this study delves into South Korean households’ willingness to pay (WTP) for this preservation. One thousand households nationwide were sampled and surveyed through face-to-face individual interviews. Annual household income tax was selected as the payment vehicle. Dichotomous choice questioning was chosen as the WTP induction method. A spike model was selected as a method for modelling a WTP of zero. The main results showed statistical significance. Annual WTP per household and national WTP were obtained as KRW 4487 (USD 3.92) and KRW 125.75 billion (USD 109.83 million), respectively. When a 10-year payment period and a 4.5% discount rate were adopted, the value was KRW 766.14 billion (USD 669.12 million). South Korean households placed considerable value on the preservation of the ecological integrity of the HRE through interstate cooperation. Full article

The flow routing process plays a crucial role in underpinning the execution of real-time operations within interbasin water transfer projects (IWTPs). However, the water transfer process within the supplying area is significantly affected by the time lag of water flow over extended distances, which results in a misalignment with the water demand process in the receiving area. Hence, there is an imperative need to investigate the flow routing patterns in long-distance water transfer processes. While MIKE11(2014 version) software and the Muskingum method are proficient in simulating flow routing within a water transfer network, they fall short in addressing issues arising from mixed free-surface-pressure flows in water transfer pipelines. This study enhanced the capabilities of the MIKE11(2014 version) software and the Muskingum method by introducing the Preissmann virtual narrow gap method to tackle the challenge of simulating mixed free-surface-pressure flows, a task unattainable by the model independently. This approach provides a clear elucidation of hydraulic characteristics within the water transfer network, encompassing flow rates and routing times. Furthermore, this is integrated with the Muskingum inverse method to compute the actual water demand process within the supplying area. This methodology is implemented in the context of the Han River to Wei River Diversion Project (HTWDP). The research findings reveal that the routing time for the Qinling water conveyance tunnel, under maximum design flow rate conditions, is 12.78 h, while for the south and north main lines, it stands at 15.85 and 20.15 h, respectively. These results underscore the significance of the time lag effect in long-distance water conveyance. It is noteworthy that the average errors between simulated and calculated values for the south and north main lines in the flow routing process are 0.45 m³/s and 0.51 m³/s, respectively. Compared to not using the Preissmann virtual narrow gap method, these errors are reduced by 59.82% and 70.35%, indicating a significant decrease in the discrepancy between simulated and calculated values through the adoption of the Preissmann virtual narrow gap method. This substantially improves the model’s fitting accuracy. Furthermore, the KGE indices for the flow routing model are all above 0.5, and the overall trend of the reverse flow routing process closely aligns with the simulated process. The relative errors for most time periods are constrained within a 5% range, demonstrating the reasonability and precision of the model. Full article

The coastal lowlands in East China are very sensitive to climate change and marine disasters, and much large-scale hydraulic engineering was recorded in the historical documents of the Late Holocene. In this study, AMS ¹⁴C and OSL were used to date three sedimentary profiles from the north and south coasts of inner Hangzhou Bay, and grain size and geochemical analyses including organic carbon, macro-elements, and alkaline earth metals were performed, while hydraulic engineering records in historical documents were compiled, in an attempt to reveal the sedimentary records of extreme climatic and hydrological events over the past 3000 years and to probe into the correlation between them and hydraulic engineering. The results show that the intensified chemical weathering during ca. 200 BCE to 900 CE in East China corresponded to the warm and humid climate during the Qin-Han and Sui-Tang dynasties. Salinity intrusion with rising local water levels occurred in the lowland plains along the south coast of Hangzhou Bay from 120 to 895 CE. Low-salinity water intrusion from 32 to 488 CE was also recorded in the stratigraphy of lowland plains along the north coast of Hangzhou Bay. The sedimentary records of the East Tiaoxi River basin show river floods about 2000 years ago. The above sedimentary records indicate that the relative sea level rose in the Hangzhou Bay area during the Qin-Han and Sui-Tang Warm Periods, resulting in frequent salinity intrusion and river floods, which coincided with the historical records of hydraulic engineering such as the construction of seawalls, river levees, and the enclosure of lakes for restoration of river floods during the Han and Tang dynasties. Such coincidence reflects that climate change profoundly affected the hydrological environment of the coastal areas in East China as well as the response of the human societies. Full article

High concentrations of 2-methylisoborneol (2-MIB) were reported during winter in the Paldang reservoir and North Han River, South Korea. The causes of the unusual taste and odor problems in the regulated river-reservoir system were not understood; however, a short-term solution is to flush out 2-MIB-rich water to secure water sources for over 20 million people. Approximately 150 million tons of water was released from upstream dams for 12 days (late November to early December 2018) to reduce the elevated levels of 2-MIB. Simultaneously, the spatio-temporal variations of the measured concentration of sample 2-MIB from five sites were simulated using a multi-dimensional hydrodynamics-based solute transport model to monitor the flushing effect. A modified environmental fluid dynamics code (EFDC) was adopted as the primary model framework. Five scenarios on the kinetic constants related to the characteristics of 2-MIB transport and behavior, such as conservative, net decay, and net production, were applied, and the results were compared. We found that the simulation errors on the elapsed times to satisfy the Korean drinking water monitoring standard (≤20 ngL⁻¹) were smallest with the conservative dye transport option, indicating that the physical and biochemical characteristics of 2-MIB may not play an essential role. Full article

Wuhan has a dense network of rivers and lakes. Due to the city’s development, the water system has been fragmented, the degradation of lakes is becoming increasingly severe, and the eco-environment has been significantly damaged. By collecting samples of the central surface water bodies in Wuhan, including Yangtze River water, Han River water, lake water, and precipitation, and by utilizing hydrogen and oxygen isotopes and multivariate statistical methods, the hydraulic connectivity and ecological environmental effects between the Yangtze River, the Han River, and the lakes were revealed. The results indicated the following: (1) The local meteoric water Line (LMWL) in the Wuhan area was δD = 7.47δ¹⁸O + 1.77. The river water line equation was approximately parallel to the atmospheric precipitation line in the Wuhan area. The intercept and slope of the lake waterline equation were significantly smaller. The enrichment degree of δ¹⁸O and δD was Yangtze River < Hanjiang River < lake water. (2) The cluster analysis showed that the lakes could be divided into two types, i.e., inner-flow degraded (IFD) lakes and outer-flow ecological (OFE) lakes. Urban expansion has resulted in fragmentation of the IFD lakes, changing the connectivity between rivers and lakes and weakening the exchange of water bodies between the Yangtze River and lakes. Simultaneously, evaporation has caused hydrogen and oxygen isotope fractionation, resulting in the relative enrichment of isotopes. The IFD lakes included the Taizi Lake, Yehu Lake, and the Shenshan Lake. The OFE lakes and the Yangtze River were active, evaporation was weak, and the hydrogen and oxygen isotopes were relatively depleted, mainly including the Huangjia Lake, the East Lake, the Tangxun Lake, etc. (3) The excessive deuterium (d-excess) parameter values in the Yangtze River and the Han River water were positive. In contrast, the d values in the lakes were mainly negative. In the case of a weakened water cycle, the effect of evaporation enrichment on lake water δ¹⁸O and δD had a significant impact. It is suggested that the water system connection project of “North Taizi Lake-South Taizi Lake-Yangtze River” and the small lakes connecting to large lakes project of “Wild Lake-Shenshan Lake-Tangxun Lake” should be implemented in time to restore the water eco-environment. Full article

Akinete is a survival structure in cyanobacteria that has overcome unfavorable environmental conditions and influences their perennial blooms in the freshwater system. However, the akinete cellular and biochemical properties are insufficiently explored. We analyzed the akinete structure, as well as akinete-specific proteins and their amino acid sequence. Akinetes of Dolichospermum circinale were produced from their vegetative cells isolated from the North Han River, Korea. The akinete protein was obtained using electrophoresis, and utilizing its amino acid sequences, its antibody-binding reaction potential (ig-score) was quantified. Akinete protein masses were 17 kDa–180 kDa, and the akinete protein mass was 110 kDa. The ig score was high (average 5.0121 points) in the first half of the amino acid sequence, indicating a β-turn form. The amino acid sequence, having over 50% homology with the D. circinale akinete protein, was not present in GenBank. The homology of the D. circinale akinete-specific protein was very low (9.8%) compared to that of Anabaena variabilis, indicating that its composition was substantially different, even among phylogenetically close taxa. To the best of our knowledge, this is the first report on the D. circinale akinete protein and its amino acid sequence, with preliminary information for their practical application for detecting akinetes in freshwater systems. Full article

The Hanjiang River Basin (HJRB) is an important water conservation and ecological barrier area for the South–North Water Transfer Central Project. The quantitative analysis of regional differences in vegetation changes and their main drivers is important for the monitoring of the ecological environment of the basin and formulation of ecological protection measures. Based on MODIS13Q1 data from 2000 to 2020, spatiotemporal variation characteristics of vegetation in the HJRB were analyzed using Theil–Sen + Mann–Kendall, the Hurst index, and correlation analysis. Then, we detected the drivers using an optimal parameter geographic detector. The results showed that from 2000 to 2020, the average NDVI value increased from 0.651 to 0.737, with a spatial distribution pattern of “high in the northwest and low in the southeast”, and 88.68% of the study area showed an increase in vegetation cover, while 5.80% showed a significant degradation. The positive persistence of future vegetation changes is stronger than the negative. It may show a slowdown or degradation trend, among which the vegetation restoration along the Han River and urbanized areas need to be strengthened. The factor detector indicated that the main factors influencing vegetation change were topography and climate, for which the most influential variables, respectively, were elevation (0.1979), landform (0.1720), slope (0.1647), and soil type (0.1094), with weaker influence from human activity factors. The interaction test results showed that the interaction of various geographic factors enhanced the explanatory power of vegetation changes and showed mainly nonlinear and two-factor enhancements. The dominant factor varies between sub-basins; for example, the interaction between wind speed and land use conversion was the dominant factor in the middle reaches of the HJRB; the dominant factor in the lower reaches of the HJRB was expressed as the interaction between land use conversion and temperature. Finally, the effects of the range or category of different drivers on vegetation growth were systematically analyzed. The results of the study contribute to the understanding of the dynamic changes of vegetation based on a comprehensive consideration of the interaction of topography, climate, and human activities, taking into account the totality and variability of the geographical environment, and provide a reference for the ecological restoration and rational use of vegetation resources in the HJRB. Full article

Chinese chestnut (Castanea mollissima Bl.) is one of the earliest domesticated and cultivated fruit trees, and it is widely distributed in China. Because of the high quality of its nuts and its high resistance to abiotic and biotic stresses, Chinese chestnut could be used to improve edible chestnut varieties worldwide. However, the unclear domestication history and highly complex genetic background of Chinese chestnut have prevented the efficiency of breeding efforts. To explore the genetic diversity and structure of Chinese chestnut populations and generate new insights that could aid chestnut breeding, heterozygosity statistics, molecular variance analysis, ADMIXTURE analysis, principal component analysis, and phylogenetic analysis were conducted to analyze single nucleotide polymorphism data from 185 Chinese chestnut landraces from five geographical regions in China via genotyping by sequencing. Results showed that the genetic diversity level of the five populations from different regions was relatively high, with an observed heterozygosity of 0.2796–0.3427. The genetic diversity level of the population in the mid-western regions was the highest, while the population north of the Yellow River was the lowest. Molecular variance analysis showed that the variation among different populations was only 2.07%, while the intra-group variation reached 97.93%. The Chinese chestnut samples could be divided into two groups: a northern and southern population, separated by the Yellow River; however, some samples from the southern population were genetically closer to samples from the northern population. We speculate that this might be related to the migration of humans during the Han dynasty due to the frequent wars that took place during this period, which might have led to the introduction of chestnut to southern regions. Some samples from Shandong Province and Beijing City were outliers that did not cluster with their respective groups, and this might be caused by the special geographical, political, and economic significance of these two regions. The findings of our study showed the complex genetic relationships among Chinese chestnut landraces and the high genetic diversity of these resources. Full article

Eriocheir sinensis is an euryhaline crab found from East Asia to Europe and North America. This species can live in freshwater and seawater due to the unique physiological characteristics of their life cycle, which allows them to adapt and inhabit different habitats in a wide range of environments. Despite the wealth of studies focusing on adaptation mechanism of E. sinensis to specific environmental factors, the adaptation mechanisms to wild habitats with coexisting environmental factors are not well understood. In this study, we conducted a transcriptome analysis to investigate gene expression differences related to habitat adaptation of E. sinensis from two wild habitats with different environmental factors in the Han River, Korea. A total of 138,261 unigenes were analyzed, of which 228 were analyzed as differentially expressed genes (DEGs) between the two wild habitats. Among 228 DEGs, 110 DEGs were annotated against databases; most DEGs were involved in energy metabolism, immunity, and osmoregulation. Moreover, DEG enrichment analysis showed that upregulated genes were related to biosynthesis, metabolism, and immunity in an habitat representing relatively high salinity whereas downregulated genes were related to ion transport and hypoxia response in habitats with relatively low salinity and dissolved oxygen. The present findings can serve as foundation for future E. sinensis culture or conservation approaches in natural conditions. Full article

Danjiangkou Reservoir is the water source of the mid-route of the South-to-North Water Transfer Project. The source, distribution and potential risk of antimony in its water and sediments are rarely reported. In this study, symmetrical investigation results demonstrated that the concentration of antimony in the Han sub-reservoir and water in front of the dam fluctuated at about 0.9 mg L⁻¹, while it was relatively higher and increased with the distance from the dam in Dan sub-reservoir water, with an annual average of 0.93~3.15 mg L⁻¹. In recent years, the concentration of antimony in the Danjiangkou Reservoir showed a downward trend, and the difference between the Han and Dan sub-reservoirs decreased significantly. The antimony in the sediments in the reservoir was primarily derived from the inflowing rivers, and it was higher in the Dan sub-reservoir than in the Han sub-reservoir. The concentration of antimony in the water in the reservoir was considerably higher than the background value in the watersheds, indicating that there is an external input with decreasing input intensity. The content of antimony in the sediments in the reservoir and its inflow rivers was substantially higher than the background value of watersheds, indicating that there is a certain degree of enrichment. In addition, the antimony mining industry in the water source area poses a risk to the water safety of the reservoir. Antimony is not a conventional pollutant. Consequently, the collection of antimony monitoring results is a challenging task. Additionally, this study fills the gap in regional antimony research. Furthermore, the ecological risk assessment of antimony in China is still in its infancy. Unquestionably, the study of the temporal and spatial distribution of antimony concentration will be beneficial for the protection of water sources in relevant regions. Full article

Understanding water quality events in a multiple-impoundment series is important but seldom presented comprehensively. Therefore, this study was conducted to systematically understand the explosion event of geosmin (GSM) in the North Han River (Chuncheon, Soyang, Euiam, and Cheongpyeong Reservoirs) and Han River (Paldang Reservoir), which consists of a cascade reservoir series, the largest drinking water source system in South Korea. We investigated the spatiotemporal relationship of harmful cyanobacterial blooms in the upstream reservoir (Euiam) with the water quality incident event caused by the GSM in the downstream reservoir (Paldang) from January to December 2011. The harmful cyanobacterial bloom occurred during August–September under a high water temperature (>20 °C) after a heavy-rainfall-based flood runoff event. The high chlorophyll-a (Chl-a) concentration in the upper Euiam Reservoir was prolonged for two months with a maximum concentration of 1150.5 mg m⁻³, in which the filamentous Dolichospermum circinale Kütz dominated the algal community at a rate of >99%. These parameters remarkably decreased (17.3 mg Chl-a m⁻³) in October 2011 when the water temperature decreased (5 °C) and soluble reactive phosphorus was depleted. However, high and unprecedented GSM concentrations, with a maximum value of 1640 ng L⁻¹, were detected in the downstream reservoirs (Cheongpyeong and Paldang); the level was 11 times higher than the value (10 ng L⁻¹) recommended by the World Health Organization. The concentrations of GSM gradually decreased and had an adverse effect on the drinking water quality until the end of December 2011. Our study indicated that the time lag between the summer–fall cyanobacterial outbreak in the upstream reservoir and winter GSM explosion events in the downstream reservoirs could be attributed to the transport and release of GSM through the effluent from hydroelectric power generation in this multiple-reservoir system. Therefore, we suggest that a structural understanding of the reservoir cascade be considered during water quality management of drinking water sources to avoid such incidents in the future. Full article