01 July 2021, Volume 38 Issue 7

    

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SPECIAL CONTRIBUTION
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  Hydrologic Cycle in the Source Area of Yangtze River: Research Status and Existing Problems

  CHANG Fu-xuan, HONG Xiao-feng

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 1-6. https://doi.org/10.11988/ckyyb.20201035

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  Located in the hinterland of Qinghai-Tibet Plateau, the source region of the Yangtze River is featured with high altitude, low temperature, and harsh natural conditions. As a result, with the lack of hydrometeorological monitoring and basic data, study on the hydrological cycle in this region is inadequate. In this paper, the status of researches and observations of hydrologic cycle in the source region of Yangtze River is reviewed, and existing problems and challenges are expounded. First of all, the monitoring data could not meet research requirements due to insufficient monitoring stations and their unreasonable locations as well as difficulties in operating and maintaining equipment in such unfavorable circumstances. Research on the mechanism of hydrologic cycle needs to be deepened. Such mechanism involves the trend of water resources variation, runoff of underlying surface, groundwater transport, and etc. Moreover, the structure of hydrological simulation models should be enhanced, and the applicability and versatility await verification. Measures to tackle these problems are presented as follows: monitoring stations and platforms need to be upgraded by collaborative efforts from multi-departments and trans-disciplines; international corporation in scientific research can be intensified; information service and social benefits should be taken into consideration; prototype observation and fundamental theoretical research need to be improved. Innovations should also boost in terms of observation approach, atmospheric-solid-liquid water conversion, water balance, hydro-thermal coupling, hydrologic models for alpine area, as well as global climate change impact.
RIVERLAKE SEDIMENTATION AND REGULATION
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  Evolution of Water and Sediment Processes in the Mainstream of National Nature Reserve for Rare and Endemic Fishes in the Upper Reaches of the Yangtze River under Changing Environment

  WU Hua-li, JIN Zhong-wu, ZHOU Yin-jun, LI Zhi-jing

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 7-13. https://doi.org/10.11988/ckyyb.20200599

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  The impacts of environmental changes on hydrologic processes in the mainstream of national nature reserve for rare and endemic fishes in the upper reaches of the Yangtze River are analyzed based on long series of measured water and sediment data at Xiangjiaba and Zhutuo hydrologic stations by double cumulative curve method and mathematical statistics method. Results suggest that annual runoff of the mainstream in the protected area saw no obvious downcut, but annual sediment discharge slipped sharply. The correlation between runoff and sediment discharge changed abruptly in 1998 and 2012; in the three time periods divided by the abrupt changes, the correlation coefficient R² is 0.999, 0.996 and 0.989 5 for Xiangjiaba station respectively and 0.999 6, 0.995 6 and 0.983 6 for Zhutuo station respectively. In fish spawning period from March to July and from November to December, the mean value and peak value of flow in the study area changed significantly. Take March for example, the average daily flow in the aforementioned three time periods at Xiangjiaba station increased by 34.3% and 58.5% respectively, and 16.1% and 21.1% respectively at Zhutuo station. In addition, the changes average daily of flow in most months after impoundment are more extensive than those during reservoir construction. The research findings offer theoretical basis for river habitat restoration and ecological dispatch of cascade reservoirs.
WATER RESOURCES AND ENVIRONMENT
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  Research Progress on Sampling and Pretreatment Methods of Microplastics in Fresh Water Environment

  LI Dan-wen, LIN Li, PAN Xiong, WU Xiao-hui

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 14-23. https://doi.org/10.11988/ckyyb.20200586

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  As an emerging pollutant, microplastics are widely detected in oceans, rivers, land, air and soil. For a better understanding of the research situation of microplastics in fresh water, the sampling and pretreatment methods for microplastics in freshwater system are expounded, and the development direction is discussed. The sampling objects includes water, sediment and aquatic organisms. In the extraction of microplastics, the advantages and shortcomings of different extraction solutions and extraction methods are compared. In terms of sample digestion, the strengths and weaknesses of different digestion solutions and digestion methods are analyzed. Last but not the least, the development trend and work prospect in microplastics analysis methods in future are put forward which is expected to offer reference for the development of sampling and pretreatment technology of microplastics in freshwater environment.
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  Removal of Water Phosphorus by Iron-Carbon Micro- electrolysis Material

  HU Yan-ping, WANG Zhen-hua, LI Qing-yun, LONG Meng, LI Guan-ya

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 24-28. https://doi.org/10.11988/ckyyb.20200482

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  The filler compaction and channeling during the phosphorus removal by traditional iron-carbon micro-electrolysis fillers not only undermine the removal effect, but also increase the amount of mud produced by carbon particles from the filler and raise the subsequent processing cost. In view of this, a new type of iron-carbon micro-electrolysis material composed of iron-based materials and carbon fiber was employed to remove total phosphorus in a lake in Wuhan. The removal effect and the influence of treatment time on total iron concentration and turbidity of water were also examined with comparisons with those of carbon fiber and iron-based materials. Results demonstrated that treated for 10 hours with intermittent aeration, the phosphorus removal rate by the present iron-carbon micro-electrolysis material, iron-based material, and carbon fiber were 80.00%, 76.73%, and 2.86%, respectively. Treated for 72 hours with iron-carbon micro-electrolysis and placed static for 96 hours, the total phosphorus concentration in water dropped from 0.052 mg/L to 0.012 mg/L, reaching class II standard in Surface Water Environmental Quality Standard (GB 3838-2002). The turbidity and total iron concentration in water barely changed, stabilizing at 4.14 NTU and 0.089 mg/L, respectively. Moreover, no filler compaction or channeling was observed for the new iron-carbon micro- electrolysis material suspended in the water body. Only iron floc was produced in the water treatment process, which overcame the increase in mud production caused by the loss of carbon particles in traditional iron-carbon filler. Therefore, the new type iron-carbon micro-electrolysis material can overcome the problems of filler compaction, channeling and large mud production in traditional iron-carbon micro-electrolysis reaction process, and in the meantime enhance the phosphorus removal rate with no evident increase in turbidity and total iron concentration.
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  Characteristics of Regional Precipitation Events Using EEMD Method: A Case Study of Beijing-Tianjin-Hebei Region

  HAN Jia-hao, ZHANG Qi, SHEN Ling-ling

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 29-35. https://doi.org/10.11988/ckyyb.20200460

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  Regional precipitation affects the water cycle and thus has a profound impact on various sectors of the social economy. The Beijing-Tianjin-Hebei region, as the political, economic and cultural center of China, suffers from frequent flood and drought disasters. Complete understanding of the precipitation characteristics of the region is in urgent need. A total of 552 regional precipitation events was identified from the daily precipitation data from 1989 to 2018 at 173 meteorological stations in Beijing-Tianjin-Hebei region. The Ensemble Empirical Mode Decomposition (EEMD) method was employed to examine the characteristics and temporal and spatial distributions of regional precipitation events in the region from three aspects: duration, coverage and precipitation intensity. Results unveiled that: 1) the frequency of precipitation events in Beijing-Tianjin-Hebei region displayed a trend of declining along with the elongation of duration and the expansion of coverage area; but such declining trend gradually alleviated. The intensity of regional precipitation events reached the highest frequency around 10 mm. Duration, coverage, and precipitation intensity all had obvious positive effect on the comprehensive intensity index. 2) The interannual change of comprehensive intensity of regional precipitation events in the Beijing-Tianjin-Hebei region presented a cycle of about 10 years; but the long-term trend was not insignificant. 3) Precipitation events distributed more in the middle while less in the northwest in the Beijing-Tianjin-Hebei region. The research findings offer support for the water resources planning and disaster prevention and reduction for the region.
WATERSOIL CONSERVATION AND ECOLOGICAL RESTORATION
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  Sensitivity Analysis of VG Model Parameters under Rainfall Infiltration Using HYDRUS-1D Simulation

  BI Biao, QIAN Yun-kai, AI Xian-feng, ZHAO Ting-ning

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 36-41. https://doi.org/10.11988/ckyyb.20200446

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  The aim of this study is to quantify the influence of hydraulic parameters of soil on three output variables of HYDRUS-1D. The three parameters include:dynamic distribution of soil moisture in 10 cm layer, cumulative infiltration capacity, and migration distance of wetting front. By individually perturbing the five hydraulic parameters, namely, θ_r, θ_s, K_s, α, and n in the HYDRUS-1D VG model, we examined the sensitivities of these five parameters under rainfall infiltration by using the modified Morris screening method. Results manifested the importance of determining the intervals of parameter sensitivity to simplifying tests process. The sensitivities of model parameters changed with time depending on different output results. Boundary condition is also a crucial factor that affects the model parameter sensitivity. In addition, the sensitivity of each of the five parameters differs with various research objects. In conclusion, the accuracy of highly sensitive parameters and the authenticity of boundary conditions should be ensured.
FLOOD PREVENTION AND DISASTER REDUCTION
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  Optimizing Drainage Pattern in Jiangbei Urban District of Hangzhou

  JIANG Jian-ling

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 42-45. https://doi.org/10.11988/ckyyb.20200605

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  On the basis of analyzing the causes of waterlogging and the overall regional defense capacity of Jiangbei urban district of Hangzhou City, we present urban encirclement schemes to optimize the drainage pattern in the hope of offering reference for the decision-making of flood control planning and regulation. At present in Hangzhou we already have a series of flood control and drainage projects including the comprehensive water resources planning for Hangzhou, Jiaxing, and Huzhou region (hereafter referred to as Hang-Jia-Hu region), the urban flood control and disaster reduction planning for Hangzhou City, the special planning of west Hangzhou Kechuang corridor, and others. Under such background, we established the one-dimensional unsteady flow mathematical model of flood control for the eastern plain of Hang-Jia-Hu region, and calculated the implementation effect and impacts of three urban encirclement schemes involving different arrangements of canals and control gates. Results show that by constructing sluices and pumps along the north control line and together with optimizing operation, the Jiangbei urban district of Hangzhou City could meet drainage standards and actively prevent from waterlogging on one hand, and reduce the flood control pressure on downstream areas to the greatest extent and take into account the flood control of the river basin on the other. The research finding is of referential value for the flood control and drainage of cities in the middle and upper reaches of the eastern Hang-Jia-Hu plain.
ENGINEERING SAFETY AND DISASTER PREVENTION
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  Dam Deformation Prediction Model Based on Bayesian Optimization and LightGBM

  GAO Zhi-xin, BAO Teng-fei, LI Yang-tao, WANG Yi-bing

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 46-50. https://doi.org/10.11988/ckyyb.20200444

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  Deformation as an intuitive monitoring indicator reflects the operation state of a dam. Existing intelligent methods for dam deformation prediction are prone to local optimum and are inapplicable in the case of large-scale data. In this paper, we combine a fast and efficient gradient boosting framework Light Gradient Boosting Machine (LightGBM) based on the decision tree with the global optimization algorithm, Bayesian optimization, to predict dam deformation. Taking two concrete dams as case study, we compared the modelling result with those of multiple linear regression, support vector regression, and multi-layer perceptron to verify the applicability of the present model. The RMSE and MAE of the proposed model are both superior to those of other methods, which manifests the feasibility and superiority of the model. In addition, LightGBM can evaluate the importance of input parameters and select the features that affect dam deformation, so as to determine the factors that have more significant influence on dam deformation and offer reference for following safety assessment.
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  Spatiotemporal Distribution of Post-operation Deformation of Shuibuya Concrete-faced Rockfill Dam

  XU Kun, YANG Qi-gui

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 51-57. https://doi.org/10.11988/ckyyb.20200512

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  By analyzing long-term monitoring data, we examined the post-operation deformation (defined as the deformation in stable running stage) of the maximum-height section and the downstream surface of Shuibuya concrete-faced rockfill dam (CFRD), and hence revealed the spatiotemporal distributions of post-operation deformation of the dam. We found that settlement is the dominant form of deformation in the stable running stage of the dam. The increment of settlement in stable running stage increased with the rise of elevation, while the increment of horizontal displacement bore no correlation with elevation. The increment of tri-directional deformation of the downstream surface in stable running stage was similar to that of general deformation of CFRD. The deformation time of maximum-height section differed from that of downstream surface: the deformations of downstream surface mostly occurred in the later stage, while the settlement of the maximum-height section was observed mainly before the later stage. Moreover, the annual settlement increment of each monitoring point fluctuated. The distribution of the annual settlement increment of the downstream surface was obvious, and the annual settlement increment of almost all monitoring points at downstream surface showed a decreasing trend with time. According to the research results, we recommend to improve the compaction quality of dam materials in the middle-upper part of the dam, especially on the downstream side in order to control the post-operation deformation of the dam.
ROCKSOIL ENGINEERING
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  Simulation Test on Physical Clogging of Foam Plastic Filter Infiltrated with Storm-water

  XU Zhen-fei, WU Qing-hua, ZHANG Jia-fa

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 58-65. https://doi.org/10.11988/ckyyb.20200365

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  As a novel filter layer material, foam plastic has good application prospects in the sponge city infiltration system. Yet, the selection of filter layer specifications in the presence of different storm-water suspended solid characteristics and the maintenance of filter layer after clogging are still problems to be solved. In view of this, we acquired the particle size gradations and concentration ranges of storm-water suspended solids in the study area through sampling and analysis at a typical site, and then simulated the physical clogging process of foam plastic filter layer via indoor tests. We divided the storm-water particles into five groups according to their gradations and prepared suspension solutions respectively for the filter layer infiltration simulation test. We suggest that for fine particles of [0.1,0.25) mm and <0.1 mm, the pore size of the corresponding filter layer with the best retention effect is 80 ppi and 100 ppi, respectively. Moreover, we prepared solutions of various concentration with suspended solid particles of combined gradations to carry out infiltration simulation experiments for two types of filter layers, and obtained the change rules of the dropping rate of foam plastic filter layer's permeability coefficient with the suspension concentration as follows: in the presence of the same filter pore size, greater concentration of rainwater suspended solid led to larger clogging rate; at the same suspension concentration, smaller pore size of filter gave rise to faster clogging. The changes in permeability coefficient were also proven by turbidity analysis results of the filtrate.
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  Experimental Study on Deformation Failure and Crack Propagation of End Jointed Rock Bridge under Different Loading Rates

  CHEN Yong-feng, ZHANG Hai-dong, ZHAO Guang-chen

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 66-72. https://doi.org/10.11988/ckyyb.20200421

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  The rock bridge in rock mass controls the stability of slope. The failure of rock bridge generates loading rate effect due to the influence of excavation speed. It is of great significance to explore the deformation and failure characteristics and crack propagation mechanism of rock bridge in slope under the influence of loading rate. By prefabricating cracks at the end of rock-like material, we prepared test specimens with middle rock bridge and examined the failure characteristics, crack initiation, propagation and penetration laws of specimens with different rock bridge lengths under varying loading rates with the aid of digital imaging. The crack propagation mechanism was also revealed in line with the theory of fracture mechanics. Results manifested that: (1) The stress-strain curve displayed post-peak fluctuation and stress slump characteristics. With the rising of loading rate, peak strength swelled whereas peak displacement shrinks. (2) Five patterns of crack propagation were identified: the upper crack ran through the lower end face; the rock bridge penetrated through; the lower crack ran through the left end face; the lower crack ran through the lower end face; and the lower crack ran through the upper end face. (3) During the failure of specimen, the number of cracks declined with the rising of loading rate. Cracks started from the tip of the lower crack. (4) The expression of stress intensity factor at crack tip considering closure effect under uniaxial compression was derived, and the theoretical calculation and experimental results of crack initiation angle were both within the allowable range of error. (5) The change of surface strain field of specimen intensified with the rising of loading rate, and the failure of sample was caused by the accumulation of damage in the early stage.
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  Analysis of Grouting Effect of Water-rich Sandstone Based on Inversion of Permeability by Acoustic Logging

  CHEN Bin, ZHAO Li-quan, HU Hui-hua, YAO Sheng-dan, ZHAO Yan-lin, LIU Tong

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 73-79. https://doi.org/10.11988/ckyyb.20200392

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  To address the difficulty in point-by-point detection of the grouting effect of water-rich broken sand strata, we propose to evaluate the detailed water-sealing effect of grouting via inversion of permeability using acoustic logging. On the basis of Wyllie-Clemenceau's formula and Kozeny-Carman's formula, we established an acoustic velocity-permeability model for water-rich sandstone. With a foundation grouting project in Hunan as research object, we obtained the acoustic velocity and permeability of rock core and rock strata before and after grouting through core test, acoustic logging, and hydraulic fracturing test. By fitting the core test results with the model, we found a nonlinear negative correlation between acoustic velocity and permeability with an obvious cut-off point of change rate in the curve. Grouting affects the rock matrix acoustic velocity and the exponent to the matrix nature. By comparing the permeability calculated by logging acoustic velocity with the hydraulic fracturing test results, we verified the reliability of the model. In addition, we built a quantitative evaluation system for the grouting effect of water-rich sandstone on the basis of calculated permeability, and evaluated the case using this system.
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  Optimization and Micro-characteristics of Compound Preparation for Remediation of Chromium-contaminated Soil

  LI Xi-lin, YU Xiao-wan, LIU Ling, MA Zheng, FAN Ming

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 80-87. https://doi.org/10.11988/ckyyb.20200703

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  Single reduction method and solidification/stabilization technology are inefficient in dealing with chromium polluted soil. A method combining pollution reduction and soil solidification/stabilization is presented in this paper. The optimum mix proportion of the compound treating agent composing reducing agent, adsorbent and curing agent was determined through single-doping test and L₉(3⁴) orthogonal test. The solidified/stabilized chromium contaminated soil was microscopically characterized by scanning electron microscopy. Results show that the optimum mix proportion of the compound is: the dosage of calcium polysulfide is three times the theoretical reducing dosage required to reduce Cr(VI) in the contaminated soil to Cr(Ⅲ) , synthetic zeolite content is 15%, and cement content is 20%. SEM analysis demonstrates that the compound alleviates the blocking effect of Cr(VI) and Cr(Ⅲ) on hydration reaction and coagulation reaction through the combined actions of reduction, adsorption, and solidification, and strengthens the curing/stabilizing effect. It also has evident effect of reducing the leaching concentration of the cured body, with the toxic leaching result meeting standard requirements.
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  Model Tests on Bearing Behavior of Composite Foundation Reinforced with Geosynthetic-encased Stone Columns Based on Artificial Soft Clay Technique

  LI Liang-yong, CHEN Jian-feng, PENG Ming

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 88-95. https://doi.org/10.11988/ckyyb.20200489

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  A new type of artificial soft clay composed of sodium bentonite and glycerol was made to study the mechanical feature of composite foundation reinforced with geosynthetic-encased stone columns (GECs) in soft clay foundation under undrained or poorly drained conditions. Four groups of model tests of GECs composite foundation with varied reinforcement stiffness and length under embankment load were carried out for this purpose. The test results were compared with those in well drained condition. Results showed that: the settlement of the GECs composite foundation obviously decreases with an increase of reinforcement stiffness. The stress concentration ratio is much larger than that in well drained condition. The columns with high reinforcement stiffness are likely to tilt outward the embankment. The columns with low reinforcement stiffness, however, bend inward the embankment. For the partially encased stone columns, the settlement is significantly greater than the fully encased stone columns. The stress concentration ratio of the partially encased stone columns is smaller than that of the fully encased stone columns, but larger than that of stone columns. The GECs bend inward the embankment in the encased parts and bulge in the non-encased parts. Drainage condition significantly affects the displacement and stability of GECs. Generally, the bending deformation is smaller in the columns with well drained conditions and vice versa. It is found from the study that fully encased stone columns with high reinforcement stiffness and well drained conditions are of great importance to improve the stability of road embankment.
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  Analytical Method for Flexural Toppling-Shear Sliding Failure of Counter-tilted Rock Slopes

  AN Ming-xu, ZHANG Hu

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 96-101. https://doi.org/10.11988/ckyyb.20200471

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  At present, the cantilever beam model based on the limit equilibrium theory is still the main method to analyze the flexural toppling failure of counter-tilted rock slopes, but most do not consider the shear failure of the rock layer at the toe of the slope. According to the deformation and failure characteristics of rock layer, we divided the slope into three zones: stable zone in the back edge, flexural toppling zone in the middle, and shear zone in the front edge. In subsequence, we established the analytical method for flexural toppling-shear sliding failure mode and verified the analytical method through application in an engineering example and analyzed the model parameters. Results manifest that the result obtained by the proposed analytical method is in good agreement with actual engineering. The slope stability is at the worst in the presence of large dip angle of rock layer and slope angle. The influence of slope angle on slope stability is greater than that of dip angle of rock layer. The increment in the thickness and internal friction angle of rock layer is conducive to slope stability and will widen the scope of the shear zone at slope toe.
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  Elastic-plastic Solution to Surrounding Rock of Circular Tunnel Based on Power Hardening-Ideal Plastic Model in Consideration of Seepage

  YU Xu-guang, ZHENG Hong

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 102-108. https://doi.org/10.11988/ckyyb.20200399

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  Reasonable strength criterion is of vital importance in the elastic-plastic analysis of surrounding rock of circular tunnel using power hardening-ideal plastic model. In the aim of obtaining a strength criterion suitable for the power hardening-ideal plastic model, first of all the four commonly used strength criteria for geotechnical materials were summarized; the unified linear equation of plane strain was acquired; then the unified solutions of stress, displacement and plastic zone radius of circular tunnel's surrounding rock in plastic zone and power hardening zone in the presence of seepage were deduced; and finally the theoretical strength effect, power hardening parameters, and pore water pressure on the elastic-plastic analysis of circular tunnel's surrounding rock were discussed. Research results revealed outstanding theoretical strength effect. Comparison with finite element analysis results suggest that Mogi-Coulomb criterion, unified strength theory with parameters b=1/2 and c=0, unified strength theory with parameters b=1 and c=0 are favorable; inscribed circle DP2 criterion and equivalent area circle DP4 criterion could follow in sequence; DP3 criterion and Mohr-Coulomb criterion are not recommended; circumscribed circle DP1 criterion and unified strength theory with parameters b=1 and c=1 should be used with caution. Among the power hardening parameters, the power hardening coefficient m had no impact on the radius of plastic zone, but the plastic zone displacement increased with the reduction of m; the plastic zone radius and displacement of surrounding rock both swelled with the growth of power hardening index n. The plastic zone radius, radial stress and tangential stress augmented with the climbing of pore water pressure. The research results offer an important theoretical basis for the support design of circular tunnel's surrounding rock with strong strain hardening effect.
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  A Precise Calculation Method for Earthwork Volume Based on BIM Techniques

  PENG Hui-qiong

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 109-114. https://doi.org/10.11988/ckyyb.20210288

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  In large-scale civil engineering, the quantity of earthwork is an important parameter that affects the construction schedule and the technical and economic indexes of the project. In this paper, a precise calculation method for earthwork volume is presented based on BIM(Building Information Model) techniques to improve the calculation efficiency and accuracy. Firstly, the terrain surface is divided into several rectangular subdomains, each of which is simulated with an independent thin plate spline interpolation function. Furthermore, the terrain surface is discretized with regular right-angled triangular meshes, and the meshes are refined automatically to improve and control the simulation accuracy. In subsequence, through the topological and geometrical calculation of the terrain surface and the designed slope, the accurate excavation line is obtained and the BIM model is generated automatically. Finally, the 3D excavated body is generated by the Boolean operation between the original terrain body and the excavated slope, and the precise quantity of earthwork can be acquired. Engineering practice has proved that the quantity of earthwork in large-scale civil engineering can be obtained precisely with the present method, and the design efficiency and quality are also improved.
HYDRAULIC STRUCTURE AND MATERIAL
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  Mechanical Strength, Durability and Evaluation of Ecological Efficiency of Mortar with High Volume of Slag

  CHEN Pei-yuan, HE Shi-cheng, WANG Peng-ju, HU Xiu-ping, XU Hai-jun

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 115-119. https://doi.org/10.11988/ckyyb.20200385

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  To make full use of the prominent green feature of slag concrete and accelerate its practical application, we adopted silica fume as the strength adjustor to investigate its effect on the mechanical strength and durability of mortars with 80% slag. We also evaluated the ecological efficiency of slag mortars. Experimental results demonstrate that silica fume is such an effective material to mitigate the retarded setting of mortars with high amount of slag due to dilutive effect. When 10% silica fume was added, the setting time of slag mortar was close to that of the control group. Moreover, silica fume has exerted prominent effects on the mechanical strength and durability of mortars. With 5% silica fume added, both the 28-day compressive strength and the flexural strength of mortar were much higher than those of mortar without silica fume. Consequently, the durability of mortar was also greatly improved by incorporating slag and silica fume into mortars, i.e., the capillary water absorption and electric flux of mortar reduced 8.83%-26.81% and 5.28%-36.87%, respectively. In summary, through the combined use of slag and silica fume as the alternative to 80% cement to prepare mortars, we significantly ameliorated the performance of slag mortars as well as its ecological efficiency, hence providing theoretical basis for the application and development of concrete with high volume of slag.
INFORMATION TECHNOLOGY APPLICATION
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  An Eco-environmental Management, Analysis and Evaluation System for the Lower Reaches of Jinsha River

  YANG Kun, LI Xiao-fei, GONG Liu-liu

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 120-124. https://doi.org/10.11988/ckyyb.20200436

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  This paper is presented to design and develop an eco-environmental management and analysis and evaluation system for solving the problem of insufficient information utilization and information service capacity in the eco-environmental management for the lower reaches of the Jinsha River. By incorporating the technologies of Internet of things, geographic information system, distributed file storage, system integration, and the SSM (Spring+SpringMVC+Mybatis) in the system, we can store, manage, analyze and evaluate the eco-environmental management information and monitoring data in a unified manner for the lower reaches of the Jinsha River. The system uses a semi-tight integration method to integrate the powerful EFDC model with open source code so as to connect the water quality and water temperature core computing model and information system to accomplish online operation of water quality and water temperature models. The system will assist in the eco-environmental management for the lower reaches of the Jinsha River.
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  Design and Case Study of Water Resources Management System Based on Cluster Architecture

  FENG Kuai-le, ZHOU Jian-zhong, LIU Yi, TANG Zheng-yang, ZHOU Chao

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 125-131. https://doi.org/10.11988/ckyyb.20200416

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  With the development and utilization of modern water conservancy information resources, the traditional integration method of centralized water resource management system has been unable to meet the high performance and the service orientation demands of professional models. Microservice system architecture encapsulates the model into service resources and provides modularized low-level functions for high-level intelligent applications. It is a fine-grained, low-coupling, and scalable approach to integrating water resource management models. In the servitization of professional model, the operational efficiency of a single service is the key factor for the overall system performance. In this paper, an effective service clustering development method of water resource management system is proposed based on the micro-service system architecture in consideration of the servitization demand of professional models. On the one hand, the horizontal performance of professional model services is expanded through mainstream container technology; and on the other hand, the load balancing of network and services is achieved via gateway technology. The related technologies were applied in the decision support system of water resources management for the lower reaches of the Jinsha River-Three Gorges cascade hydropower plants. The research findings offer reference for the design and development of water resources information system.
SPECIAL COLUMN OF SCITECH INNOVATION FOR THE REGULATION AND PROTECTION OFCHANGJIANG RIVER: PROCEEDINGS OF THE 2020 ANNUAL MEETING OF CHANGJIANGTECHNOLOGY AND ECONOMY SOCIETY
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  General Strategy of Exploiting and Protecting Yangtze River Water Resources in Response to the Green Development of Yangtze River Economic Zone

  WU Zhi-guang, YUAN Zhe

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 132-136. https://doi.org/10.11988/ckyyb.20210324

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  Undergone five years of eco-environmental governance and green transformation in social-economic development, remarkable achievements have been made in the exploitation and protection of water resources of the Yangtze River. Nevertheless, the negative impact of extensive economic growth in the past four decades could not be eradicated in a short term. The ecological environment in the Yangtze River is still facing daunting tasks in complicated circumstances, which have restricted the sustainable development of the Yangtze River Economic Belt. To promote green development and realize a win-win situation between economic development and eco-environmental improvement are new requirements and challenges for the green development of the Yangtze River Economic Belt. In this paper, we identified the deficiencies in exploiting and protecting water resources in the Yangtze River from the perspective of green development. With ecology as priority and green development as guiding principle, we put forward the major tasks and priorities of a systematic protection accommodating green development. The objectives of protection work are being efficient, moderate, balanced, and harmonious. The paper is expected to offer reference for exploring the new path of green development in the Yangtze River Economic Zone with ecology as priority.
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  Analysis of Monthly Precipitation Characteristics of Ankang Station in Upper Hanjiang River from 1950 to 2014 Based on Chaos Theory

  ZHAO Zi-yang, WANG Hong-rui, ZHAO Yan, HU Li-tang, LIU Hai-jun

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 137-142. https://doi.org/10.11988/ckyyb.20210007

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  By analyzing the monthly precipitation trend of Ankang Station from 1950 to 2014, we found that the precipitation at Ankang changes periodically. Having determined the delay time and embedded dimension of the nonlinear system of precipitation at Ankang using autocorrelation function method and C-C correlation integral method, we reconstructed the phase space of the precipitation series, and identified the chaotic characteristics of precipitation by using the G-P correlation dimension method and the maximum Lyapunov exponent method. Results reveal that the G-P correlation dimension algorithm indicates no chaos, while the maximum Lyapunov exponent method suggests chaos. With the existing 780 monthly precipitation data, we can forecast up to seven months of precipitation. The research finding offers scientific support for the runoff forecast in Hanjiang River and its downstream areas.
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  Distribution Characteristics and Sources of Heavy Metals in Surface Sediments and Bank Soils of Major Rivers in Source Region of Yangtze River

  LIU Min, DENG Wei, ZHAO Liang-yuan, HU Yuan, HUANG Hua-wei, GAO Fei

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 143-149. https://doi.org/10.11988/ckyyb.20201371

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  The concentrations of 14 heavy metals in sediments and surrounding soils of major rivers in the source region of the Yangtze River were detected by using inductively coupled plasma mass spectrometry and atomic fluorescence spectrophotometer. The accumulation of heavy metals was evaluated by enrichment factor method, and the distribution characteristics and sources of heavy metals were also analyzed. Results unraveled that except for Ni, Pb, Cd, and Hg, all other heavy metals in river sediments were lower than the background values of sediments in China; however, Hg, Ni, and Cd were enriched in sediments. Compared with other rivers in the source region, Tuotuo River suffered from a relatively high concentration of Cd, Tongtian River was subjected to high concentrations of Hg and Fe, while Chumar River boasted a low concentration of all heavy metals. The heavy metals in sediments were mainly affected by natural factors. In terms of bank soils, the concentrations of Ni, Pb, Cd, and Ti were slightly higher than the background values of soils in Qinghai Province, yet with light enrichment.Compared with the soils along other rivers in the source region, the bank soil along Dangqu River had high concentrations of Cr, Ni, and Cu, and Tuotuo River Pb, Cd, Sb, and Tl, whereas Tongtian River saw a high concentration of V. The heavy metals in bank soils along rivers were mainly affected by natural factors, and also some affected by traffic factors. The research achievements offer fundamental support for the eco-environmental protection in the source region of the Yangtze River.
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  Estimation and Analysis of Agricultural Water-saving Potential in Central Yunnan Water Receiving Area

  GU Shi-xiang, ZHU Yun, LI Ya-long, LIU Feng-li, XIONG Yu-jiang

  Journal of Changjiang River Scientific Research Institute. 2021, 38(7): 150-154. https://doi.org/10.11988/ckyyb.20210017

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  To maximize the agricultural water saving potential and achieve a sustainable growth, we estimated and analyzed the water saving potential in the water receiving area of central Yunnan Province. Based on meteorological and field survey data, we designed five scenarios of water saving and calculated the water saving potentials in each scenario using the calculation method recommended by the Ministry of Water Resources with 2017 as the current benchmark year and 2030 as the planning level year. We also analyzed the regional food security and the benefits of water saving investment. Results demonstrate that in the planning level year 2030, the average irrigation water use coefficient in the study area will reach 0.69, water saving irrigation rate will amount to 80%, and highly-efficient water saving irrigation rate 30%. By adjusting the rice planting area within the range of -10%-3% according to the actual planting structure based on the current benchmark year, we can save 187.82 million m³ of agricultural water on the prerequisite of ensuring regional good security.