27 results on '"Changkun Ma"'
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2. A study on compressibility and permeability of tailings with different particle sizes under high pressure
- Author
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Changkun Ma, Ruixin Li, Chao Zhang, Xiaogang Guo, and Xueting Li
- Subjects
Geology ,Geotechnical Engineering and Engineering Geology - Published
- 2023
3. Influence of particle size scale on mechanical properties of tailings under high pressure
- Author
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Shucheng Gan, Xiaogang Guo, Lei Ma, Chao Zhang, Zhenkai Pan, and Changkun Ma
- Subjects
Scale (ratio) ,High pressure ,Metallurgy ,Earth and Planetary Sciences (miscellaneous) ,Particle size ,Geotechnical Engineering and Engineering Geology ,Granular material ,Tailings - Abstract
Particle size has an effect on the mechanical properties of tailings materials. The mechanics and crushing characteristics of tailings at high pressure are a research focus for high tailings dams. Tailings with different particle sizes were tested under laboratory high-pressure triaxial compression. The effect of particle size on the compression characteristics of tailings was studied, along with the strength and deformation of tailings with different particle sizes. Based on particle size distribution, the crushing characteristics of the tailings were quantitatively analysed. A mathematical model for crushing index and tailings strength was established. Under high pressure, shearing contraction failure occurred in the tailings samples. The stress–strain relation of the tailings showed strain softening at low confining pressure and continuous hardening at high confining pressure. The confining pressure at which the stress–strain relation changed from strain softening to strain hardening increased with increased particle size. Due to the higher degree of particle crushing for coarse tailings during the shearing under high pressure, the volume deformation of the coarse samples decreases continuously further. It shows increase in the amount of particle breakage as the confining pressure, but the increase rate decreased with the confining pressure increased. The Box Lucas loading accumulation model was used to describe the change in particle breakage with confining pressure. The peak strength of tailings increased exponentially with the improved relative crushing rate.
- Published
- 2022
4. Modelling the artificial forest (Robinia pseudoacacia L.) root–soil water interactions in the Loess Plateau, China
- Author
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Hongyu Li, Yi Luo, Lin Sun, Xiangdong Li, Changkun Ma, Xiaolei Wang, Ting Jiang, and Haoyang Zhu
- Abstract
Plant root–soil water interactions are fundamental to vegetation–water relationships. Soil water availability and distribution impact the temporal–spatial dynamics of roots and vice versa. In the Loess Plateau (LP) of China, where semi-arid and arid climates prevail and deep loess soil dominates, drying soil layers (DSLs) have been extensively reported in artificial forestland. While the underlying mechanisms that cause DSLs remain unclear, they hypothetically involve root–soil water interactions. Although available root growth models are weak with respect to simulating the rooting depth, this study addresses the hypothesis of the involvement of root–soil water interactions in DSLs using a root growth model that simulates both the dynamic rooting depth and fine-root distribution, coupled with soil water, based on cost–benefit optimization. Evaluation of field data from an artificial black locust (Robinia pseudoacacia L.) forest site in the southern LP positively proves the model's performance. Further, a long-term simulation, forced by a 50-year climatic data series with varying precipitation, was performed to examine the DSLs. The results demonstrate that incorporating the dynamic rooting depth into the current root growth models is necessary to reproduce soil drying processes. The simulations revealed that the upper boundary of the DSLs fluctuates strongly with infiltration events, whereas the lower boundary extends successively with increasing rooting depth. Most infiltration was intercepted by the top 2.0 m layer, which was the most active zone of infiltration and root water uptake. Below this, the percentages of fine roots (5.0 %) and water uptake (6.2 %) were small but caused a persistently negative water balance and consequent DSLs. Therefore, the proposed root–water interaction approach succeeded in revealing the intrinsic properties of DSLs; their persistent extension and the lack of an opportunity for recovery from the drying state may adversely affect the implementation of artificial afforestation in this region as well as in other regions with similar climates and soils.
- Published
- 2022
5. High-stress permeability and consolidation characteristics of flocculanted fine tailings
- Author
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Hanmin Zhou, Chao Zhang, Shucheng Gan, Xiaogang Guo, and Changkun Ma
- Subjects
Flocculation ,Materials science ,Consolidation (soil) ,fungi ,food and beverages ,Geotechnical Engineering and Engineering Geology ,Microstructure ,Tailings ,High stress ,Permeability (earth sciences) ,Earth and Planetary Sciences (miscellaneous) ,Geotechnical engineering ,sense organs ,skin and connective tissue diseases - Abstract
Fine-grained tailings have poor permeability and a long consolidation time, but treatment with flocculants can improve their mechanical properties. Changes in the physical and engineering propertie...
- Published
- 2021
6. In Situ Rainwater Collection and Infiltration System Alleviates the Negative Effects of Drought on Plant-Available Water, Fine Root Distribution and Plant Hydraulic Conductivity
- Author
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Changkun Ma, Haobo Meng, Biao Xie, Qian Li, Xiangdong Li, Beibei Zhou, Quanjiu Wang, and Yi Luo
- Subjects
Forestry ,fine-root distribution ,plant-available water ,hydraulic characteristics ,Robinia pseudoacacia ,Loess Plateau - Abstract
Soil water status and fine-root characteristics are the foundation for implementing forest water-management strategies in semiarid forest plantations, where rainwater is always the sole source of water for plant growth. Rainwater management and utilization are effective strategies to alleviate water scarcity in semiarid areas as ground water is always inaccessible there. Through the implementation of an in situ rainwater collection and infiltration system (IRCIS), we investigated the effects of IRCIS on soil water and fine-root distributions in the 0–5 m soil profile in a wet (2015, 815 mm) and a dry year (2016, 468 mm) in rainfed Robinia pseudoacacia forests in the Loess Plateau region of China. The results showed drought significantly decreased plant water availability and hydraulic conductivity of roots and branches, but strongly increased soil moisture deficits and fine-root (1.5 m) soil water in dry years to maintain normal growth and resist drought stress. The results of this study will contribute to the formulation of appropriate strategies for planning and managing rainwater resources in forest plantations.
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- 2022
- Full Text
- View/download PDF
7. Rainfall Partitioning by Evergreen and Deciduous Broad-Leaved Xerophytic Tree Species: Influence of Rainfall, Canopy Characteristics, and Meteorology
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Changkun Ma, Qian Yao, Haobo Meng, Beibei Zhou, Quanjiu Wang, and Yi Luo
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rainfall partitioning ,semi-arid region ,throughfall ,stemflow ,interception loss ,xerophytic species ,Geography, Planning and Development ,Aquatic Science ,Biochemistry ,Water Science and Technology - Abstract
Understanding how rainfall is partitioned into throughfall, stemflow, and interception losses by xerophytic trees is important for evaluating afforestation projects and modeling hydrological budgets in semi-arid regions. However, information regarding rainfall partitioning by xerophytic trees and the controlling factors in semi-arid regions remains underrepresented in the literature. We examined whether plant functional groups have a significant impact on rainfall partitioning in two xerophytic trees (evergreen species: Pinus tabuliformis (Pinales:Pinaceae) hereafter called P. tabuliformis, deciduous species: Robinia pseudoacacia L. (Fabales:Fabaceae) hereafter called R. pseudoacacia) commonly used for afforestation on the semi-arid Loess Plateau of China, and evaluated the effects of rainfall, canopy characteristics and meteorological variables on rainfall partitioning. The event-based gross rainfall, throughfall and stemflow were measured during both growing (May–October) and dormant (January–April and November–December) seasons in 2015 and 2016 within an afforested watershed in semi-arid Loess Plateau of China. During our study period, the average rainfall depth for growing season and dormant season was 8.4 mm (varied from 0.2 to 57.6 mm) and 5.6 mm (varied from 0.2 to 41.6 mm), respectively. On average, the measured throughfall, stemflow and interception loss for R. pseudoacacia accounted for 81.8%, 1.4% and 16.8% of gross rainfall, respectively. Corresponding values for P. tabuliformis were 75.1%, 0.7% and 24.1%, respectively. Significant differences (p < 0.05) in stemflow were detected between R. pseudoacacia and P. tabuliformis during both the growing and dormant seasons. The rainfall partitioning components were significantly positively correlated with individual rainfall amounts. The minimum rainfall required to generate stemflow was 5.2 mm for R. pseudoacacia and 5.9 mm for P. tabuliformis during the growing season, and 3.1 mm for R. pseudoacacia and 6.0 mm for P. tabuliformis during the dormant season. Smaller rainfall events contributed to a lower percentage of rainfall amount, throughfall and stemflow but higher percentage of canopy interception loss. The percentage of throughfall and stemflow showed an increased tendency with increasing rain-fall characteristics, while the increasing rainfall characteristics resulted in a decrease in relative interception loss. During the growing season, leaf area index is significantly correlated with throughfall and interception loss of R. pseudoacacia, while there were no significant correlation between meteorological variables and rainfall partitioning. In general, the depth of rainfall partitioning can be predicted reasonably well by using the developed multiple regression models, but the proportions of rainfall partitioning had a relative lower accuracy using the developed models, especially for relative interception loss. To better predict canopy interception loss, other plant morphological and meteorological variables should be considered.
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- 2022
- Full Text
- View/download PDF
8. IAA Plays an Important Role in Alkaline Stress Tolerance by Modulating Root Development and ROS Detoxifying Systems in Rice Plants
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Changkun Ma, Shuai Yuan, Biao Xie, Qian Li, Quanjiu Wang, and Mingan Shao
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Inorganic Chemistry ,Organic Chemistry ,General Medicine ,alkaline stress ,auxin ,ROS detoxifying mechanism ,rice (Oryza sativa) ,Physical and Theoretical Chemistry ,Molecular Biology ,Spectroscopy ,Catalysis ,Computer Science Applications - Abstract
Auxin regulates plant growth and development, as well as helps plants to survive abiotic stresses, but the effects of auxin on the growth of alkaline-stressed rice and the underlying molecular and physiological mechanisms remain unknown. Through exogenous application of IAA/TIBA, this study explored the physiological and molecular mechanisms of alkaline stress tolerance enhancement using two rice genotypes. Alkaline stress was observed to damage the plant growth, while exogenous application of IAA mitigates the alkaline-stress-induce inhibition of plant growth. After application of exogenous IAA to alkaline-stressed rice, dry shoot biomass, foliar chlorophyll content, photosynthetic rate in the two rice genotypes increased by 12.6–15.6%, 11.7–40.3%, 51.4–106.6%, respectively. The adventitious root number, root surface area, total root length and dry root biomass in the two rice genotypes increased by 29.3–33.3%, 26.4–27.2%, 42.5–35.5% and 12.8–33.1%, respectively. The accumulation of H2O2, MAD were significantly decreased with the application of IAA. The activities of CAT, POD, and SOD in rice plants were significantly increased by exogenous application of IAA. The expression levels of genes controlling IAA biosynthesis and transport were significantly increased, while there were no significant effects on the gene expression that controlled IAA catabolism. These results showed that exogenous application of IAA could mitigate the alkaline-stress-induced inhibition of plant growth by regulating the reactive oxygen species scavenging system, root development and expression of gene involved in IAA biosynthesis, transport and catabolism. These results provide a new direction and empirical basis for improving crop alkaline tolerance with exogenous application of IAA.
- Published
- 2022
9. Irrigation with Magnetized Water Alleviates the Harmful Effect of Saline–Alkaline Stress on Rice Seedlings
- Author
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Changkun Ma, Qian Li, Zhaoxin Song, Lijun Su, Wanghai Tao, Beibei Zhou, and Quanjiu Wang
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Nitrogen ,Organic Chemistry ,Oryza ,General Medicine ,Salt Tolerance ,magnetized water ,saline–alkaline stress ,nitrogen absorption ,rice (Oryza sativa) ,Plant Roots ,Catalysis ,Computer Science Applications ,Inorganic Chemistry ,Seedlings ,Physical and Theoretical Chemistry ,Molecular Biology ,Spectroscopy - Abstract
Saline–alkaline stress suppresses rice growth and threatens crop production. Despite substantial research on rice’s tolerance to saline–alkaline stress, fewer studies have examined the impact of magnetic water treatments on saline–alkaline-stressed rice plants. We explored the physiological and molecular mechanisms involved in saline–alkaline stress tolerance enhancement via irrigation with magnetized water using Nipponbare. The growth of Nipponbare plants was inhibited by saline–alkaline stress, but this inhibition was alleviated by irrigating the plants with magnetized water, as evidenced by greater plant height, biomass, chlorophyll content, photosynthetic rates, and root system in plants irrigated with magnetized water compared to those irrigated with non-magnetized water. Plants that were irrigated with magnetized water were able to acquire more total nitrogen. In addition, we proved that rice seedlings irrigated with magnetized water had a greater root NO3−-nitrogen concentration and root NH4+-nitrogen concentration than plants irrigated with non-magnetized water. These findings suggest that treatment with magnetized water could increase nitrogen uptake. To test this hypothesis, we analyzed the expression levels of genes involved in nitrogen acquisition. The expression levels of OsNRT1;1, OsNRT1;2, OsNRT2;1, OsAMT1;2, OsAMT2;1, OsAMT2;2, OsAMT2;3, OsAMT3;1, OsAMT3;2, and OsAMT3;3 were higher in plants exposed to magnetized water medium compared to those exposed to non-magnetized water media. We further demonstrated that treatment with magnetized water increases available nitrogen, NO3−-nitrogen content, and NH4+-nitrogen content in soil under saline–alkaline stress. Our results revealed that the increased resistance of rice seedlings to saline–alkaline stress may be attributable to a very effective nitrogen acquisition system enhanced by magnetized water.
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- 2022
- Full Text
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10. Spatio-Temporal Study on Irrigation Guarantee Capacity in the Northwest Arid Region of China
- Author
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Xue Zhao, Wanghai Tao, Lijun Su, Yan Sun, Zhi Qu, Weiyi Mu, Changkun Ma, and Yuyang Shan
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irrigation water requirement ,effective irrigation water ,irrigation guarantee capacity index ,irrigated agriculture ,Geography, Planning and Development ,Aquatic Science ,Biochemistry ,Water Science and Technology - Abstract
Irrigation guarantee capacity is the critical factor in evaluating the development level of irrigated agriculture and is also a future development trend. It is necessary to carry out scientific planning and reasonable allocation of irrigation water resources to ensure the sustainable development of irrigated agriculture and improve the efficiency and effectiveness of water resource utilization. This study is based on remote sensing meteorological data and the principles of the Miami model and water balance. We calculated the annual irrigation water requirement and effective irrigation water, and used the ratio between the effective irrigation water and irrigation water requirement as the basis for evaluating an irrigation guarantee capability index. By using irrigation guarantee capability evaluation indicators from multiple years, we evaluated and assessed the irrigation guarantee capability in the arid region of northwest China. In addition, we analyzed three indicators (i.e., irrigation water requirement IWR, effective irrigation water EIW, and irrigation guarantee capacity index IGCI) to explore the rational allocation of water resources in the northwest arid area. IWR, EIW, and ICGI in northwest China from 2001 to 2020 were analyzed, and the average values were 379.32 mm, 171.29 mm, and 0.50, respectively. Simultaneously, an analysis was conducted on the temporal and spatial distribution of IWR, EIW, and IGCI in the northwest region of China from 2001 to 2020. The results indicated that the rainfall in the southwestern edge of the Yellow River Basin and the eastern part of the Qaidam Basin could meet the irrigation water demand. The northwest edge of the Yellow River Basin, the central Hexi Inland River Basin, most of Northeast Xinjiang, central and southeastern Xinjiang, and other regions mainly rely on irrigation to meet agricultural water requirements. The rest of the region needs to rely on irrigation for supplementary irrigation to increase crop yield. All districts in the ‘Three Water Lines’ area of northwest China should vigorously develop sprinkler irrigation, micro-irrigation, pipe irrigation, and other irrigation water-saving technologies and support engineering construction. Under the premise of ensuring national food security, they should reduce the planting area of rice, corn, and orchards, and increase the planting area of economic crops such as beans and tubers in the ’Three Water Lines’ area. That is conducive to further reducing the agricultural irrigation quota and improving the matching degree of irrigation water resources. It provides a scientific reference for optimizing water resource allocation and improving irrigation water-use efficiency in northwest arid areas.
- Published
- 2023
11. Approximate analytical solution to equation for two-dimensional soil-water movement in ponding infiltration based on numerical simulation
- Author
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Yuyang Shan, Lijun Su, Wanghai Tao, Yan Sun, Manli Duan, Changkun Ma, and Quanjiu Wang
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Soil Science ,Agronomy and Crop Science ,Earth-Surface Processes - Published
- 2023
12. Influence of rock percentage on strength and permeability of tailing-waste rock mixtures
- Author
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Chao Zhang, Wu Shangwei, Zhenkai Pan, Changkun Ma, Qinglin Chen, Lei Zhang, and Haiming Liu
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Pollution ,Materials science ,media_common.quotation_subject ,0211 other engineering and technologies ,Geology ,02 engineering and technology ,Permeability coefficient ,010502 geochemistry & geophysics ,Geotechnical Engineering and Engineering Geology ,01 natural sciences ,Tailings ,Permeability (earth sciences) ,Friction angle ,Nature Conservation ,Geotechnical engineering ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,media_common - Abstract
The strength and permeability of tailing-waste rock mixtures directly affect deposits’ stability for an alternative co-disposal technique. In the mixed co-disposal method, the void of the waste rock is filled with tailings, while the waste rock forms the particle skeleton. This method does not only improve deposits stability but also potentially reduces acid pollution. In this study, the rock percentage influence on the shear strength and permeability of tailing-waste rock mixtures was investigated by carrying out large triaxial tests and permeability tests. The shear strength, enhanced strength mechanism, and mixture permeability were analyzed. The results indicate that the shear strength and internal friction angle of the tailing-waste rock mixtures gently increased until the rock percentage reached 30% and then rapidly increased with the further increase of the rock percentage. The permeability coefficient of the mixtures slowly increased until the rock percentage reached 50% and then rapidly increased with the further increase of the rock percentage. The tailings washed out of the waste rock skeleton when the permeability was large. In this paper, 50% of waste rock is recommended for building mixture deposits.
- Published
- 2020
13. A power function model for simulating creep mechanical properties of salt rock
- Author
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Jun Zhou, Changkun Ma, Huan Li, Ngaha Tiedeu William, and Jaak J.K. Daemen
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Materials science ,0211 other engineering and technologies ,Metals and Alloys ,General Engineering ,Model fitting ,02 engineering and technology ,Mechanics ,Physics::Geophysics ,Corrosion ,Stress level ,Stress (mechanics) ,Creep ,Metallic materials ,Particle flow ,Power function ,021102 mining & metallurgy ,021101 geological & geomatics engineering - Abstract
In this paper, a new micro-creep model of salt rock is proposed based on a linear parallel bonded model (LPBM) using the two-dimensional particle flow code (PFC2D). The power function weakening form is assumed to describe the variation of the parallel bonded diameter (PBD) over time. By comparing with the parallel-bonded stress corrosion (PSC) model, a smaller stress fluctuation and smoother creep strain-time curves can be obtained by this power function model at the same stress level. The validity and adaptability of the model to simulate creep deformation of salt rock are verified through comparing the laboratory creep test curves and the Burgers model fitting result. The numerical results reveal that this model can be capable of capturing the creep deformation and damage behavior from the laboratory observations.
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- 2020
14. Influence of Clay Mineral Content on the Mechanical Properties and Microfabrics of Tailings
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Chao Zhang, Zhenkai Pan, Changkun Ma, Lei Ma, and Xueting Li
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inorganic chemicals ,Chemistry ,Metallurgy ,Clay minerals ,complex mixtures ,Tailings - Abstract
Clay mineral content has an important influence on the mechanical behavior of tailings, and the mechanical behavior of tailings directly affects the stability of tailings dams. XRF and XRD tests were carried out on tailings from three different regions. The chemical and mineral compositions of the tailings are analyzed. The strength and failure deformation of tailings were studied by carrying out laboratory triaxial compression tests. The effect of clay content on the stress path of tailings was investigated. The microfabric of tailings samples was examined with scanning electron microscopy (SEM) and nitrogen adsorption tests. The results show that the confining pressure corresponding to the samples exhibiting strain hardening increases with increasing clay mineral content in the tailings. The cohesion of tailings increases linearly, and the specific surface area decreases as the content of clay minerals increases. Nitrogen adsorption test results reveal from a microscopic point of view that changes in pore structure are associated with the content of clay minerals. The higher the content of clay minerals is, the higher the proportion of micropores (aggregated interior). Macroscopically, the overall porosity decreases and the fineness of the pores increases with clay content, which will directly affect the mechanical properties of tailings.
- Published
- 2021
15. Modelling the artificial forest (Robinia pseudoacacia L.) root-soil water interactions in the Loess Plateau, China
- Author
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Xiangdong Li, Xiaolei Wang, Lin Sun, Ting Jiang, Changkun Ma, Yi Luo, Hongyu Li, and Haoyang Zhu
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Water balance ,Infiltration (hydrology) ,Loess ,Soil water ,Environmental science ,Soil horizon ,Soil science ,Precipitation ,Interception ,Arid - Abstract
Plant root–soil water interactions are fundamental to vegetation–water relationships. Soil water availability and distribution impact the temporal–spatial dynamics of roots and vice versa. In the Loess Plateau (LP) of China, where semiarid and arid climates prevail and deep loess soil is dominant, drying soil layers (DSLs) have been extensively reported in artificial forest land; however, the underlying mechanism remains unclear. This study proposes a root growth model that simulates both the dynamic rooting depth and fine root distribution, coupled with soil water, based on cost–benefit optimisation. Evaluation of field data at an artificial forest site of black locust (Robinia pseudoacacia L.) in the southern LP positively proves its performance. Further, a long-term simulation was performed to address the DSL issues, which were forced by a 50-year climatic data series, under variations in precipitation. The results demonstrate that incorporating the dynamic rooting depth into the currently available root growth models is necessary for reproducing the drying soil processes. The top 2.0 m is the most active zone of infiltration and root water uptake, and below which the fractions of fine roots and uptake are small but cause a persistently negative water balance and consequent DSLs. The upper boundary of the DSLs fluctuates strongly with infiltration events, while the lower boundary extends successively owing to the interception of most infiltration by the top 2.0 m layer. Coupling the root–water interactions helps to reveal the intrinsic properties of DSLs, with the persistent extension of its thickness and rare opportunities for recovery from the drying state. This study may have negative implications for the implementation of artificial afforestation in this semiarid region, as well as in other regions of similar climate and soils.
- Published
- 2021
16. Regional spatial variability of root-zone soil moisture in arid regions and the driving factors — a case study of Xinjiang, China
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Tong Liu, Chunlei Zhao, Changkun Ma, Mingan Shao, Xiaoxu Jia, and Xiangdong Li
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Driving factors ,Hydrology ,010504 meteorology & atmospheric sciences ,0208 environmental biotechnology ,Soil Science ,02 engineering and technology ,01 natural sciences ,Arid ,020801 environmental engineering ,Root zone soil moisture ,Environmental science ,Spatial variability ,Water cycle ,China ,Water content ,Surface water ,0105 earth and related environmental sciences - Abstract
Soil moisture is a key element of the hydrological cycle, and it significantly impacts the surface water and energy fluxes. However, a knowledge gap exists on the spatial variability of root-zone soil moisture at the regional scale in arid and hyperarid regions. Thus, soil moisture measurements at 142 sites were taken in Xinjiang (northwest China), and the relationships between soil moisture and 19 environmental factors were analyzed. The results showed that both absolute gravitational soil water content (SWC) and relative extractable water (REW) increased with increasing soil depth in the 0–100 cm soil profile. It generally decreased in the order of cropland > forestland > grassland > shrubland > bare land. Semivariograms suggested that SWC had moderate spatial dependence over a large range of 473–558 km, and REW was more randomly distributed at the regional scale in Xinjiang. Redundancy analysis suggested that environmental factors could explain 47.5%–50.9% of the variability of soil moisture, which was more strongly driven by land surface factors (p 0.05). Soil properties and other local variables explained, respectively, 40.7% and 32.3% of the variability of soil moisture in the 0–100 cm soil profile. Soil properties independently accounted for 12.8% and 28.1% of the variability in soil moisture in the 0–50 and 50–100 cm soil layers, respectively. Soil texture, field capacity, wilting point, organic carbon, bulk density, land use, and normalized difference vegetation index were the dominant factors influencing soil moisture variations.
- Published
- 2019
17. Effect of fine-grained dipping interlayers on mechanical behavior of tailings using discrete element method
- Author
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Zhenkai Pan, Chao Zhang, Chunhe Yang, Changkun Ma, and Qinglin Chen
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Materials science ,Applied Mathematics ,General Engineering ,Magnetic dip ,02 engineering and technology ,Slip (materials science) ,01 natural sciences ,Tailings ,Discrete element method ,Contact force ,010101 applied mathematics ,Computational Mathematics ,020303 mechanical engineering & transports ,0203 mechanical engineering ,0101 mathematics ,Composite material ,Anisotropy ,Analysis - Abstract
Due to the presence of fine-grained interlayers (frequently called lenticles), the stability of tailings dams can deteriorate. In this study, a two-dimensional numerical model with flexible boundary was constructed, and biaxial tests were carried out for samples with interlayers at different dip angles. The influence of the interlayer inclination on the mechanical properties of tailings was analyzed. The simulation results revealed that the shear strength of tailings with interlayers decreases with the increase in the interlayer dip angle. Obvious anisotropy of shear strengths was observed due to the presence of interlayers. All the deformations of the samples with interlayers were well captured in the DEM simulations. Bulging deformations were found in the samples with interlayers at dip angles of 0°, 15° and 30°. Shear slip along the fine interlayer plane was generated in the samples with interlayers with dip angles of 45° and 60°. The principal orientation of the contact unit normal and the normal contact force aligns with the loading direction for the samples with interlayer at small dip angle (i.e., 0°). However, for the sample with interlayer at large dip angle (i.e., 60°), the principal orientation trends to the direction normal to the interlayer.
- Published
- 2019
18. Strength and deformation of tailings with fine-grained interlayers
- Author
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J.J.K. Daemen, Chunhe Yang, Chao Zhang, Qinglin Chen, Zhenkai Pan, and Changkun Ma
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Materials science ,Composite number ,0211 other engineering and technologies ,Magnetic dip ,Geology ,02 engineering and technology ,Slip (materials science) ,Strain hardening exponent ,010502 geochemistry & geophysics ,Geotechnical Engineering and Engineering Geology ,01 natural sciences ,Tailings ,Strain softening ,Friction angle ,Composite material ,Anisotropy ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences - Abstract
Due to the presence of fine-grained interlayer structures (usually called lenticles), the stabilities of tailings dams deteriorate. In this study, the strength and deformation of tailing samples containing fine-grained interlayers were studied by undrained tests. Based on the Coulomb theory, the slip mechanism of tailing samples was investigated. The results indicate that the stress-strain relationship of the samples that contain interlayers of large dip angles (i.e., 45° or 60°) is typical strain softening. The stress-strain relationship of the samples, with the interlayers dipping with small angles (i.e., 0° or 15°), is strain hardening. The mechanical parameters, e.g., shear strength, internal friction angle and cohesion, decrease with the increase in the dip angle of the interlayer. In tests, three different deformation patterns, i.e., bulging, slip and composite deformation, were observed from the samples with interlayers of small, large and medium dip angles, respectively (the medium dip angle is 30°). The slip occurred along the interlayer plane of the samples. When the angle of the interlayer is near 60°, the strength and deformation of the samples are controlled by the fine-grained interlayer. The findings of this study can provide reference for the stability evaluation of anisotropic tailing dams and other similar structures.
- Published
- 2019
19. Contrasting streamflow regimes induced by melting glaciers across the Tien Shan – Pamir – North Karakoram
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Lin Sun, Rong Gan, Philippe Ciais, Xiaolei Wang, Yi Luo, Chansheng He, Shilong Piao, Changkun Ma, Yiqing Zhang, Institute of Geographic Sciences and Natural Resources Research (IGSNRR), Chinese Academy of Sciences [Changchun Branch] (CAS), Institute of Tibetan Plateau Research, Chinese Academy of Sciences [Beijing] (CAS), Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University [Beijing], Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-ATC (ICOS-ATC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), University of Chinese Academy of Sciences [Beijing] (UCAS), Northwest A and F University, Western Michigan University [Kalamazoo], Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
- Subjects
China ,Asia ,010504 meteorology & atmospheric sciences ,0208 environmental biotechnology ,Climate change ,lcsh:Medicine ,02 engineering and technology ,01 natural sciences ,Article ,Water Supply ,Streamflow ,Freezing ,Ice Cover ,Precipitation ,Glacial period ,[SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology ,[SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology ,lcsh:Science ,Ecosystem ,0105 earth and related environmental sciences ,geography ,Multidisciplinary ,geography.geographical_feature_category ,Geography ,lcsh:R ,Glacier ,15. Life on land ,6. Clean water ,020801 environmental engineering ,13. Climate action ,Snowmelt ,Environmental science ,Climate model ,lcsh:Q ,Physical geography ,Surface runoff - Abstract
International audience; The glacierized Tien Shan-Pamir-Karakoram mountain complex supplies water to about 42 million people. Yet, the knowledge about future glacial runoff in response to future climate is limited. Here, we address this issue using a hydrological model, that includes the three components of glacial runoff: ice melt, snowmelt and the runoff of rainfall over ice. The model is forced by climate projections of the CMIP5 models. We find that the three components exhibit different long-term trajectories, sometimes opposite in sign to the long-term trend in glacier impacts. For the eastern slope basins, streamflow is projected to increase by 28% (ranging from 9 to 44%, from climate model variation (CMV)) by the late 21 st century, under the representative concentration pathway, RCP8.5. Ice melt contributes 39% (25 to 65%, CMV) of the total streamflow increase. However, streamflow from the western slopes is projected to decrease by 5% (−24 to 16%, CMV), due to the smaller contribution of ice melt, less precipitation and higher evapotranspiration. Increasing water supply from the eastern slopes suggests more water availability for currently degraded downstream ecosystems in the Xinjiang province of China, while the likely decreasing streamflow in Central Asian rivers on the western slopes indicates new regulations will be needed. The Tien Shan-Pamir-Karakoram (TPK) mountain complex is the "water tower" of the Central Asian countries east of the Aral Sea (
- Published
- 2018
20. Approximate analytical solutions for one-dimensional soil water movement equation with arbitrary initial conditions
- Author
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Lijun Su, Fangliang Liu, BeiBei Zhou, Wanghai Tao, Yan Sun, Yuyang Shan, Changkun Ma, and Quanjiu Wang
- Subjects
Soil Science ,Agronomy and Crop Science ,Earth-Surface Processes - Published
- 2022
21. Comparative transcriptome analysis of two rice genotypes differing in their tolerance to saline-alkaline stress
- Author
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Huanhuan Tai, Huan Qiu, Changkun Ma, An Yang, and Qian Li
- Subjects
Physiology ,Molecular biology ,Plant Science ,Biochemistry ,Salt Stress ,Transcriptome ,chemistry.chemical_compound ,Sequencing techniques ,Plant Growth Regulators ,Gene Expression Regulation, Plant ,Plant Resistance to Abiotic Stress ,Homeostasis ,RNA-Seq ,Nicotianamine biosynthetic process ,Multidisciplinary ,Ecology ,Phenylpropionates ,Phenylpropanoid ,Gene Ontologies ,Jasmonic acid ,Eukaryota ,RNA sequencing ,Genomics ,Salt Tolerance ,Plants ,Up-Regulation ,Experimental Organism Systems ,Plant Physiology ,Medicine ,Research Article ,Genotype ,Iron ,Science ,Down-Regulation ,Biology ,Research and Analysis Methods ,Biosynthesis ,Genes, Plant ,Plant and Algal Models ,Stress, Physiological ,Plant-Environment Interactions ,Osmotic Shock ,Genetics ,Plant Defenses ,Grasses ,KEGG ,Abiotic stress ,Plant Ecology ,Gene Expression Profiling ,Ecology and Environmental Sciences ,Organisms ,Biology and Life Sciences ,Computational Biology ,Oryza ,Cell Biology ,Plant Pathology ,Genome Analysis ,Gibberellins ,Organic acid metabolic process ,Gene expression profiling ,Molecular biology techniques ,Gene Ontology ,chemistry ,Seedlings ,Animal Studies ,Rice ,Physiological Processes - Abstract
Saline-alkaline stress is an abiotic stress that suppresses rice plant growth and reduces yield. However, few studies have investigated the mechanism by which rice plants respond to saline-alkaline stress at a global transcriptional level. Dongdao-4 and Jigeng-88, which differ in their tolerance to saline-alkaline stress, were used to explore gene expression differences under saline-alkaline stress by RNA-seq technology. In seedlings of Dongdao-4 and Jigeng-88, 3523 and 4066 genes with differential levels of expression were detected, respectively. A total of 799 genes were upregulated in the shoots of both Dongdao-4 and Jigeng-88, while 411 genes were upregulated in the roots of both genotypes. Among the downregulated genes in Dongdao-4 and Jigeng-88, a total of 453 and 372 genes were found in shoots and roots, respectively. Gene ontology (GO) analysis showed that upregulated genes were enriched in several GO terms such as response to stress, response to jasmonic acid, organic acid metabolic process, nicotianamine biosynthetic process, and iron homeostasis. The downregulated genes were enriched in several GO terms, such as photosynthesis and response to reactive oxygen species. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that Dongdao-4 seedlings were specifically enriched in the biosynthesis of secondary metabolites such as diterpenoids and phenylpropanoids. The upregulated genes that were involved in secondary metabolite biosynthesis, amino acid biosynthesis, betalain biosynthesis, organic acid metabolic process, and iron homeostasis pathways may be central to saline-alkaline tolerance in both rice genotypes. In contrast, the genes involved in the diterpenoid and phenylpropanoid biosynthesis pathways may contribute to the greater tolerance to saline-alkaline stress in Dongdao-4 seedlings than in Jigeng-88. These results suggest that Dongdao-4 was equipped with a more efficient mechanism involved in multiple biological processes to adapt to saline-alkaline stress.
- Published
- 2020
22. Unfolding Non-structural Carbohydrates from Sapling to Dying Black Locust on China’s Loess Plateau
- Author
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Changkun Ma, Xiaoxu Jia, Qingyin Zhang, and Mingan Shao
- Subjects
0106 biological sciences ,Biomass (ecology) ,biology ,Plant physiology ,Growing season ,Plant Science ,Loess plateau ,biology.organism_classification ,Temperate deciduous forest ,010603 evolutionary biology ,01 natural sciences ,nervous system ,Agronomy ,Dry weight ,Agronomy and Crop Science ,Tree species ,Locust ,010606 plant biology & botany - Abstract
Non-structural carbohydrates (NSC) play important roles in metabolic processes of plants and represent important functional traits in plant adaptation to the external environment. However, there are few reports concerning intra-annual NSC distribution in temperate deciduous forests, especially for the purpose of comparison among different stand ages on China’s Loess Plateau. Here, NSC allocation dynamics with age ring-porous black locust tree was determined for the growing (May) and dormant (November) seasons over the period from sapling to dying trees—defined as a completely defoliated tree with dried branches in the growing season. It was noted that regardless of tree age, NSC concentration was highest in coarse roots [16.4 g per 100 g of dry mass (16.4% DM)] and stems (15.1% DM). At the tree level, NSC concentration was highest (14.3% DM) in a 30-year-old stand in November and lowest (4.1% DM) in dying stands in May. The pool of NSC at tree level was highest (25.2 kg DM per tree) in 30-year-old stands in November and lowest (0.13 kg DM per tree) in sapling stands in May. The concentration of NSC was significantly lower in May than in November for all tree ages, organs, and biochemical components. The results underscored the importance of NSC in plant growth on China’s Loess Plateau. It also provided a useful insight into the dynamics of NSC from sapling to dying broadleaved tree species.
- Published
- 2017
23. Comparative modeling of the effect of thinning on canopy interception loss in a semiarid black locust (Robinia pseudoacacia) plantation in Northwest China
- Author
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Changkun Ma, Yi Luo, and Mingan Shao
- Subjects
Forest floor ,Canopy ,Hydrology ,Stemflow ,010504 meteorology & atmospheric sciences ,Thinning ,0207 environmental engineering ,02 engineering and technology ,Throughfall ,01 natural sciences ,Basal area ,Environmental science ,Canopy interception ,Interception ,020701 environmental engineering ,0105 earth and related environmental sciences ,Water Science and Technology - Abstract
Canopy interception loss is a key component of forest hydrological cycle that determine the amount of net rainfall reaching forest floor together with drought/climate stressors affecting dryland forest plantations. A good understanding of the relationship between canopy interception loss and forest management such as thinning is important for improved watershed management and ecological services. In this study, we measured event-based rainfall partitioning for a thinned (TH, with 38% basal area removed) and a control (CT) Robinia pseudoacacia forest plantation during leafed and leafless seasons in 2015 in the semiarid Loess Plateau region in China. Interception loss from both forest plots were simulated using the Revised Gash Analytical Model (RGAM) and the WiMo model. The results showed that observed annual throughfall, stemflow and interception loss were respectively 80.8%, 1.7% and 17.5% of the gross rainfall under CT. The corresponding values under TH were 87.9%, 0.8% and 11.3%, respectively. The RGAM and WiMo models were well calibrated and validated using filed data collected in leafed and leafless seasons. The analyses suggested that models accurately predicated interception loss under both CT and TH conditions and captured seasonal variations in canopy and meteorological parameters. The RGAM model was most sensitive to the ratio of mean evaporation rate to mean rainfall intensity, and canopy storage capacity in leafed season, and to the ratio of mean evaporation rate to mean rainfall intensity in leafless season. Moreover, 37.2% and 42.1% of the interception in leafed season evaporated from the canopy respectively during rainfall event and after rainfall. The corresponding values for leafless season were respectively 49.3% and 22.4%. Overall, the performance of the optimized RGAM and WiMo models were satisfactory with respect to modeling error (−6.9 − −2.9%) and Nash-Sutcliffe model efficiency (0.80–0.94), although that of the optimized RGAM model was slightly superior to WiMo model. The models would facilitate the implementation of water-oriented management in semiarid forest plantations through a more accurate simulation of the impact of thinning on interception loss.
- Published
- 2020
24. Mechanical behavior and particle breakage of tailings under high confining pressure
- Author
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Chao Zhang, Qinglin Chen, Zhenkai Pan, and Changkun Ma
- Subjects
Calcite ,Materials science ,Constitutive equation ,Geology ,Geotechnical Engineering and Engineering Geology ,Overburden pressure ,Tailings ,chemistry.chemical_compound ,chemistry ,Breakage ,Axial strain ,Particle ,Composite material ,Deformation (engineering) - Abstract
The mechanical behavior and particle breakage of tailings under high confining pressure are the theoretical reference to analyze the stability of high tailings dams. Consolidated drained (CD) triaxial compression tests were carried out using a high-pressure triaxial apparatus. The strength and deformation characteristics of tailings were studied. The constitutive relation of tailings was deduced under high confining pressure. The particle breakage of tailings was analyzed qualitatively and quantitatively. The tailings exhibit strain-softening under low confining pressure and strain-hardening under high confining pressure. A modified hyperbolic model was deduced to describe the stress-strain behavior under high confining pressure. Under high confining pressure the volumetric strain always decreases with an increase in axial strain. Under low confining pressure, only a few indentations are observed on the surface of marked calcite particles. By contrast, a lot of indentations are observed on the surface of marked calcite particles under the high confining pressure. The number of broken particles increases with an increase in the confining pressure, but the increasing tendency gradually decreases.
- Published
- 2020
25. Environmental controls on sap flow in black locust forest in Loess Plateau, China
- Author
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Lin Sun, Xiaoxu Jia, Yi Luo, Mingan Shao, Xiangdong Li, and Changkun Ma
- Subjects
0106 biological sciences ,Multidisciplinary ,010504 meteorology & atmospheric sciences ,biology ,Ecology ,Vapour Pressure Deficit ,lcsh:R ,Flow (psychology) ,lcsh:Medicine ,Loess plateau ,biology.organism_classification ,Atmospheric sciences ,01 natural sciences ,Article ,Thermal dissipation ,Environmental science ,lcsh:Q ,lcsh:Science ,Water use ,Locust ,010606 plant biology & botany ,0105 earth and related environmental sciences ,Transpiration - Abstract
Black locust accounts for over 90% of artificial forests in China’s Loess Plateau region. However, water use of black locust is an uphill challenge for this semi-arid region. To accurately quantify tree water use and to explain the related hydrological processes, it is important to collect reliable data for application in the estimation of sap flow and its response to environmental factors. This study measured sap flow in black locust in the 2015 and 2016 growth seasons using the thermal dissipation probes technique and laboratory-calibrated Granier’s equation. The study showed that the laboratory calibrated coefficient α was much larger than the original value presented by Granier, while the coefficient β was similar to the original one. The average daily transpiration was 2.1 mm day−1 for 2015 and 1.6 mm day−1 for 2016. Net solar radiation (Rn) was the key meteorological factor controlling sap flow, followed by vapor pressure deficit (VPD) and then temperature (T). VPD had a threshold control on sap flow at threshold values of 1.9 kPa for 2015 and 1.6 kPa for 2016. The effects of diurnal hysteresis of Rn, VPD and T on sap flow were evident, indicating that black locust water use was conservative.
- Published
- 2017
26. The modelling of rainfall interception in growing and dormant seasons for a pine plantation and a black locust plantation in semi-arid Northwest China
- Author
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Yi Luo, Xiaoxu Jia, Changkun Ma, Xiangdong Li, and Mingan Shao
- Subjects
Hydrology ,Canopy ,Stemflow ,010504 meteorology & atmospheric sciences ,0207 environmental engineering ,02 engineering and technology ,Throughfall ,01 natural sciences ,Arid ,Deciduous ,Environmental science ,Afforestation ,Leaf area index ,Interception ,020701 environmental engineering ,0105 earth and related environmental sciences ,Water Science and Technology - Abstract
Interception loss can remove a significant portion of rainwater from forested ecosystems. Therefore, the quantification and modelling of interception loss are of significant importance if human and ecosystem water demands are to be balanced under a future changing climate. This is particularly true for semi-arid/arid regions, where afforestation has become an important ecological restoration measure to tackle desertification, poverty and climate change. However, quantification and modelling of interception loss of plantations in these regions have rarely been reported. In the present study, rainfall interception loss was quantified and modelled over a one-year period (January-December 2016) for a deciduous broad-leafed R. pseudoacacia plantation and an evergreen needle-leaf P. tabuliformis plantation (common afforestation tree species) situated in the semi-arid Loess Plateau of China. The stand age, density, canopy cover and leaf area index of R. pseudoacacia during the study period were 15 years, 2000 tree ha−1, 0.48 and 1.41 m2 m−2, respectively. The corresponding values for Pinus tabuliformis were 17 years, 1200 tree ha−1, 0.62 and 2.53 m2 m−2. The measured throughfall, stemflow and derived estimates of interception loss for R. pseudoacacia were 81.1%, 1.3% and 17.6%, respectively. The corresponding values for P. tabuliformis were 75.4%, 0.7% and 23.9%. Given that the weather conditions experienced by the two forest stands were similar, the observed higher interception loss for P. tabuliformis can be explained by the higher canopy storage capacity and wet canopy evaporation rate of this species. The revised Gash analytical model of rainfall interception was well calibrated and validated against field measurements and was able to simulate the cumulative interception loss at two forest stands accurately, and it also effectively captured the seasonal variation (leafed growing and leafless dormant seasons), provided that the optimized wet-canopy evaporation rates were used. The revised model was highly sensitive to the canopy storage capacity and changes in the ratio of mean wet canopy evaporation to mean rainfall intensity and less sensitive to canopy cover, but it was found to be fairly insensitive to the trunk storage capacity.
- Published
- 2019
27. Analysis of the plugging process of the leaking interlayer in a thin interbedded salt cavern gas storage of Jintan (China) by high-pressure grouting and potential applications
- Author
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Nan Zhang, Yinping Li, Changkun Ma, Xiangsheng Chen, Xilin Shi, and Chunhe Yang
- Subjects
Petroleum engineering ,business.industry ,020209 energy ,Grout ,Energy Engineering and Power Technology ,02 engineering and technology ,engineering.material ,Geotechnical Engineering and Engineering Geology ,law.invention ,Viscosity ,Fuel Technology ,020401 chemical engineering ,Rheology ,law ,Natural gas ,0202 electrical engineering, electronic engineering, information engineering ,engineering ,Coupling (piping) ,0204 chemical engineering ,Diffusion (business) ,Spark plug ,business ,Geology ,Leakage (electronics) - Abstract
The open hole of wellbore may pass through one or several mudstone interlayers during the construction of the salt cavern gas storage in thin interbedded salt mines. Once an interlayer is formed, leakage occurs that will cause the sealing failure of the wellbore. Based on the treatment project executed to ameliorate the wellbore sealing failure in Jintan's (China) salt cavern gas storage, a feasible grouting scheme and plugging evaluation criteria are proposed for similar, leaking interlayers. Combined with geological conditions and leaking types used to establish a radial grouting model, theoretical and numerical solutions for the plugging range are implemented. According to the grouting and plugging parameters used for analyses, the engineering practice indicates that the squeeze ultra-fine grouting can successfully plug this leaking interlayer and the depleted wellbore meets the requirements of storing natural gas that can be used for secondary utilization. The sealing effect mainly depends on the plugging range, which is affected by the grouting parameters, physicochemical properties of grout, and by the fluid–solid coupling. The results show that the viscosity rheology can inhibit grout diffusion, while the grout–rock coupling can promote grout diffusion. Their effects are completely opposite. Finally, the established plugging evaluation criteria can be used to analyze the plugging effect in the short and long-terms, and will have a good theoretical and practical guiding significance for the formation of sealing and gas leakage analysis of underground gas storage (UGS) in the future.
- Published
- 2019
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