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【Objective】 This study aims to reveal the long-term variation patterns, abrupt change characteristics, and driving factors of water and sediment fluxes of the five rivers into Poyang Lake, thereby providing scientific support for basin water resources management and water-sediment regulation strategies. 【Methods】 Based on runoff, sediment load, precipitation, and temperature data of the five rivers from 1960 to 2018, cumulative anomaly analysis, Mann-Kendall trend tests, Morlet wavelet analysis, and double mass curve methods were employed to systematically analyze the trends, abrupt change years, periodic features, and the contributions of climate change and human activities to water and sediment flux variations. 【Results】(1) The runoff from the five rivers into Poyang Lake remained generally stable throughout the study period, showing no significant long-term trend, whereas the sediment load declined markedly, with 1995 identified as the year of abrupt change and a reduction rate of 64.26%.(2) Runoff was dominated by short-term cycles of less than 10 years, associated with the regional monsoon climate, while sediment load showed long-term cycles exceeding 10 years, reflecting combined driving factors of climate change and human activities.(3) During the baseline period(1960-1995), the precipitation-sediment relationship remained stable. However, in the change period(1995-2018), the actual sediment load was much lower than the theoretical value, indicating that human activities significantly reduced sediment load per unit of precipitation.(4) Double mass curve analysis showed a stable precipitation-runoff relationship, whereas the slope of the precipitation-sediment relationship decreased significantly after 1995, indicating that sediment retention by reservoirs, soil and water conservation measures, and sand mining management were the dominant factors driving the sediment decline. 【Conclusion】 The sediment load processes of the five rivers into Poyang Lake have undergone significant changes after 1995, with human activities exerting a stronger regulatory effect than the direct impacts of climate change. Future basin management should integrate reservoir operation optimization, soil and water conservation projects, and sand mining control policies to enhance long-term sediment management and support ecological security in the Poyang Lake Basin.
【Objective】 This study aims to analyze the effects of steel fibers and rubber particles on the mechanical properties, impact energy dissipation, ductility ratio, and toughness coefficient of high-fluidity concrete. Additionally, it seeks to enhance the mechanical and impact resistance properties of high-fluidity concrete. 【Methods】 Steel fiber-reinforced rubber concrete(SFRRC) test blocks with different steel fiber contents(0.8%, 1.2%, and 1.6%) and rubber particle volume substitution rates(10%, 15%, and 20%) were designed. Drop hammer impact tests and basic mechanical property assessments were conducted. A two-parameter Weibull function model was employed to predict the impact resistance lifespan of high-fluidity SFRRC. 【Results】(1) Steel fibers enhanced the cube compressive strength and splitting tensile strength of high-fluidity concrete, whereas the incorporation of rubber particles led to a reduction in strength;(2) Steel fibers significantly improved the impact resistance of high-fluidity concrete. Notably, concrete with a rubber particle volume substitution rate of 20% and a steel fiber content of 1.6% exhibited the highest number of impact cycles before final fracture, demonstrating optimal impact resistance;(3) Under constant steel fiber content, the impact resistance ductility ratio and toughness coefficient of high-fluidity rubber concrete increased with a higher rubber particle substitution rate. 【Conclusion】 Steel fibers and rubber particles exert distinct influences on the mechanical properties of high-fluidity concrete. However, both significantly enhance its impact resistance. The impact resistance lifespan of high-fluidity SFRRC adheres to the Weibull distribution model. This study serves as a valuable reference for evaluating the impact resistance performance of high-fluidity SFRRC.
【Objective】 This study conducts a comprehensive evaluation of the hydraulic regulation of the South-to-North Water Diversion Middle Route Project(SNWD-MRP) to provide scientific support for precise scheduling decision-making. 【Methods】 Considering factors such as water level control objectives, water level decline constraints, gate regulation frequency, and response time, a hydraulic regulation evaluation system for the SNWD-MRP was established. A variable cloud comprehensive evaluation model based on a triangular distribution was developed through the integration of variable fuzzy set theory and cloud theory. Ten typical hydraulic regulation schemes for water transfer of the SNWD-MRP were evaluated and selected. 【Results】(1) Scheme 3 was relatively the best, with a comprehensive grade value of 2.76 and an evaluation grade of good. Scheme 6 was relatively the poorest, with a comprehensive grade value of 4.09 and an evaluation grade of relatively poor.(2) The evaluation grade of most scheduling schemes was average, and the comprehensive grade values were between 3.02 and 3.52, which reflected the conflict among different evaluation indicators.(3) The ranking results showed that safety-critical indicators, such as water level thresholds and fluctuation controls, had a significant influence on the evaluation of the schemes, which was consistent with the safety-first principle in the operation scheduling of the SNWD-MRP. 【Conclusion】 The variable cloud comprehensive evaluation model can effectively quantify and evaluate various scheduling schemes, and rank them accordingly. In the future, combined with the construction of digital twin technology, further research on the optimization and real-time control of regulation models can be conducted to provide technical support for intelligent scheduling of the SNWD-MRP.
【Objective】 Nighttime light remote sensing is employed to analyze the correlation between nighttime light variations and activities such as illegal sand mining and migration in the Dongping Lake area, thereby providing decision-making references for the governance and planning of the lake. 【Methods】 NPP/VIIRS and Luojia 1-01 nighttime light remote sensing data were used, along with socioeconomic data and prior information of illegal activities in the river and lake basin. An improved hidden Markov model image optimization algorithm based on a time sliding window was applied to analyze illegal sand mining and migration activities in the Dongping Lake at a large spatial scale. The regional nighttime light intensity index and regional nighttime light gradient index were adopted as statistical indicators to characterize the overall nighttime light distribution in the Dongping Lake area. 【Results】 The results showed that from 2013 to 2020, nighttime light and illegal sand mining activities in the lake surface of Laohu Town showed a downward trend. From 2014 to 2015, the regional nighttime light intensity index decreased by 37.2%. Additionally, illegal sand mining activities in the southern part of the lake area decreased sharply, indicating effective control of such activities. In 2019, nighttime light in the lake area had nearly vanished, and illegal sand mining activities had ceased entirely. Migration activities were concentrated between 2013 and 2017. In 2017, nighttime light in the northern part of the lake area disappeared, indicating the completion of the relocation. In 2020, the return migration to Laohu Town proceeded smoothly, and faint nighttime light reemerged in the Huyuan community in the northern part of the lake area. With socioeconomic development, human activities became more active. Nighttime light in the flood detention area showed an increasing trend, with the weighted radiation intensity value rising at an average of 5.31% per year from 2015 to 2020. 【Conclusion】 Nighttime light remote sensing can effectively monitor the spatiotemporal changes in illegal sand mining and migration activities in Dongping Lake, with the results aligning closely with governance effectiveness. In the future, nighttime light remote sensing can be integrated into a dynamic monitoring system for rivers and lakes, providing technical support for evidence collection related to illegal activities and for population migration analysis.
【Objective】 This study aims to reveal the evolution patterns of the hydrological processes of Urumqi Glacier No.1 at the headwaters of Urumqi River in the Tianshan Mountains and their response mechanisms to meteorological factors, providing a scientific basis for regional water resources management and climate change adaptation. 【Methods】 The Mann-Kendall(M-K) test was applied to analyze the mass balance time series of Glacier No.1 from 1989 to 2019 to identify years with abrupt changes and variation trends. Glacier No.1 was divided into accumulation zone and the ablation zone according to the equilibrium line altitude(ELA). Wavelet analysis was employed to examine the periodicity, frequency, and phase characteristics of the glacier hydrological processes. 【Results】(1) Abrupt changes in the mass balance of Glacier No.1 occurred in 1993 and 1996, and the overall trend showed a continuous decline.(2) The mass balance in both the accumulation zone and the ablation zone exhibited multi-scale responses to precipitation and air temperature, dominated by a 1-year resonance period, with a lag response of approximately 6 months.(3) The mass balance in the ablation and the accumulation zone showed resonance at a short period of 6 months and a long period of 1 year. The hydrological transfer process between the two zones exhibited an immediate response effect.(4) The effects of precipitation, mass balance in the ablation zone, and evaporation on the total runoff in the glacier area all showed a 1-year resonance period. The response of total runoff lagged behind precipitation and evaporation by 1-2 months, and lagged behind glacial meltwater by approximately 6 months. 【Conclusion】 The mass balance of Glacier No.1 exhibits staged abrupt changes and a persistent deficit trend. Its hydrological processes display multi-scale resonance characteristics, with differentiated lagged responses among hydrological variables, revealing the buffering and regulating role of glaciers in runoff generation. Under the context of global warming, particular attention should be paid to the delayed contribution of glacial meltwater to runoff, and long-term in-situ monitoring of multiple glacial-hydrological elements should be strengthened.
【Objective】 To enhance the bonding performance of near-surface-mounted carbon fiber reinforced polymer(CFRP) plates in concrete, a novel embedded anchorage reinforcement method is proposed. 【Methods】 Mechanical anchorage of CFRP plates was achieved by utilizing the clamping force generated by bolt-tightened steel anchorages. Tests were conducted to evaluate the clamping force and anchorage force of three types of anchorages with varying diameters under different bolt torque levels. Based on these results, single-lap shear tests were performed on nine bonding specimens with near-surface-mounted CFRP plates and twenty-four anchorage specimens with CFRP plates clamped by embedded anchorages. The failure modes of both types of specimens, the strain distribution in the CFRP plates, and the anchorage force were analyzed. 【Results】 The anchorage specimens exhibited two failure modes: relative slip between anchorages and plates, and tensile rupture of the CFRP plates. The anchorage force of CFRP plate specimens clamped by the three types of anchorages with different diameters was independent of concrete strength and anchorage spacing. Furthermore, specimens with larger diameter anchorages demonstrated higher anchoring capacity, and increasing the number of anchors effectively improved the anchorage force. 【Conclusion】 The load transfer mechanism between the embedded anchor-clamped CFRP plates and concrete is revealed, and the calculation formulas for the anchorage force of various anchors are derived, which provide theoretical support for the design and performance evaluation of members strengthened with CFRP plates clamped by embedded anchors.
【Objective】 This study aims to analyze the key factors affecting the regional water supply-demand balance and develop evidence-based management strategies, thereby providing theoretical support and practical pathways for promoting sustainable water use and high-quality regional development. 【Methods】 Based on water footprint and blue-green water frameworks, this study innovatively explored the mechanisms of water resources stress in the river basin from a holistic view of water resources. Taking the Yanhe River Basin as an example, the Soil and Water Assessment Tool(SWAT) model was employed to calculate basin-scale blue and green water volume, which was then coupled with a system dynamics model. Four future scenarios-natural development, water-resource-focused regulation, economic-growth-driven development, and ecological-priority management-were designed to quantitatively analyze their impacts on water resources carrying capacity, thereby proposing regulation strategies to enhance water resources carrying capacity. 【Results】 The SWAT model achieved R2 and Nash-Sutcliffe Efficiency(NSE) values of 0.69 and 0.61 during the calibration period, and 0.88 and 0.78 during validation, indicating good simulation accuracy. The multi-year average blue water volume was 1.408 billion m3, and the multi-year average green water volume was 3.193 billion m3, highlighting green water as the dominant component of the river basin′s water resources. By 2035, agricultural, industrial, domestic, and ecological water demands in the river basin were projected to increase, with the projected blue water supply reaching only 93 million m3. Under the water-resource-focused regulation scenario, the supply-demand gap was minimized, averaging 5.9 million m3. However, apple and vegetable yields deviated from the planned targets by 361 300 t and 352 700 t, respectively, and industrial output was 2.213 billion yuan lower, indicating constraints on industrial and agricultural development. Under the economic-growth-driven development scenario, the supply-demand gap was the largest, averaging-52.2 million m3, further intensifying supply-demand pressure. In contrast, the results under the ecological-priority management scenario aligned closely with the planned targets, yielding an average supply-demand gap of-12.9 million m3. 【Conclusion】 The ecological-priority management scenario achieves a water supply-demand ratio of 1.33, and the simulated values of subsystems are generally consistent with the long-term development goals. This scenario effectively achieves a dynamic balance among ecological protection, economic development, and water resources utilization, serving as a strategic reference for high-quality development in the Yanhe River Basin in the future.
【Objective】 To reveal the relationship between population growth, impervious surface expansion, and changes in water consumption, and to provide a scientific basis for the coordinated development of population, land, and water resources in Henan Province. 【Methods】 Based on panel data and remote sensing data from 2000 to 2022, the intensity difference index, decoupling index, and CCR model of data envelopment analysis were used to measure the intensity of population growth and impervious surface expansion in various cities of Henan Province, and the change trends were analyzed to reveal their influence on water consumption. 【Results】(1) The intensity of population growth and impervious surface changes in various cities of Henan Province increased. In 2010, the intensity of population growth changed from being higher than impervious surface expansion to being lower than impervious surface expansion. There was a spatial misalignment in the allocation of population and impervious surface.(2) At the provincial scale, the relationship between population and impervious surface was consistently characterized by weak decoupling, but the gap between population growth rate and impervious surface expansion rate gradually increased. At the municipal scale, the decoupling relationship between population and impervious surface underwent a process from being dominated by ″weak decoupling″ to being dominated by ″weak decoupling and strong decoupling″.(3) At the provincial scale, the effect efficiency of population was higher than that of impervious surface, and population growth was the dominant factor driving the increase in water consumption. At the municipal scale, there were regional differences in the effect efficiency of population and impervious surface on water consumption, and the dominance between population growth and impervious surface expansion alternated, demonstrating regional differentiation characteristics. 【Conclusion】 Population growth and impervious surface expansion both promote an increase in water consumption, but the correlation between population and water consumption is stronger. Henan Province should coordinate the scale and growth rate of population and impervious surface in various cities, adjust water use plans and industrial structures, and achieve the goal of coordinated development of population, land, and water resources.
【Objective】 To overcome the difficulties in constructing high earth-rockfill dams on deep overburden layers, field tests and laboratory tests on deep overburden layers are carried out to provide a scientific basis for the design of dam foundations and dam bodies. 【Methods】 Field in-situ pressuremeter tests were conducted on the deep overburden layers of the riverbed at the proposed Zhongbo hydropower station site to obtain the foundation bearing capacity parameters of different strata. Finite element numerical analysis was employed to simulate the pressuremeter test process and analyze its deformation mechanism. Based on a genetic optimization algorithm, back-analysis of the pressuremeter tests was performed to obtain the Duncan-Chang E-B model parameters of each stratum required for dam foundation settlement and deformation analysis. Large-scale laboratory triaxial tests on the dam foundation soils were also carried out to obtain the Duncan-Chang E-B model parameters. A reduction formula relating laboratory test parameters and back-analysis parameters was proposed. An engineering case study was applied to compare and validate the reduction formula. 【Results】(1) The pressuremeter test results indicated that the in-situ structure of the overburden layer and the compaction properties of the horizontal soil in the test section were the primary reasons why the back-analysis parameters were larger than those obtained from triaxial tests.(2) The slopes of the back-analysis curves from the finite element numerical analysis aligned with the measured curves from field tests, confirming the accuracy of the numerical back-analysis in capturing the pressuremeter test behavior.(3) The proposed reduction formula for laboratory test parameters and back-analysis parameters was applied to the engineering case study, and the validation results were satisfactory, indicating that the reduction formula had good predictive capability and enabled conversion between parameters obtained from laboratory tests and those from back-analysis. 【Conclusion】 The deformation calculation parameters of soil materials can be accurately obtained by back-analyzing constitutive model parameters through field pressuremeter tests and applying a reasonable reduction formula, thereby providing valuable references for similar earth-rockfill dam projects.
【Objective】 This study aims to investigate the variation in compressive strength of nano-SiO2 and hybrid fiber-reinforced epoxy resin cementitious repair materials(NF-ECRM), and to reveal the influence mechanism of epoxy resin emulsion, nano-SiO2 and polyvinyl alcohol(PVA)-steel hybrid fiber on the compressive strength. 【Methods】 Cube compressive strength tests were conducted to analyze the effects of the contents of epoxy resin, nano-SiO2, and PVA-steel hybrid fibers on the compressive strength of NF-ECRM. Scanning electron microscope tests were performed to reveal the strengthening mechanism of the compressive strength of NF-ECRM. 【Results】 With the increase in epoxy resin content, the compressive strength of epoxy resin cementitious repair materials(ECRM) and NF-ECRM both showed a decreasing trend. Meanwhile, the compressive strength of NF-ECRM gradually increased with the increase in nano-SiO2 content, while it first increased and then decreased with the increase in PVA fiber content, reaching the peak when the PVA fiber content was 0.9%. 【Conclusion】 Epoxy resin can effectively relieve internal stress in the cementitious repair material matrix and inhibit the formation and expansion of micro-cracks. Nano-SiO2 can reduce pore defects of the cementitious repair material matrix and improve the compactness of the interfacial transition zone. Moreover, PVA-steel hybrid fiber can significantly enhance the integrity and crack resistance of the cementitious repair material matrix.