Characteristics of groundwater flow field after land creation engineering in the hilly and gully area of the Loess Plateau   总被引：1，自引：0，他引：1  

Xiaoxi Yin  Luwang Chen  Jiandong He  Xiaoqing Feng  Wen Zeng 《Arabian Journal of Geosciences》2016,9(14):646

In order to study the degree of influence and control mechanism to groundwater flow field caused by land creation engineering in the hilly and gully area of the Loess Plateau, based on the geological and engineering conditions of the first stage project of Yan’an new district in China, numerical simulation of groundwater flow is carried out by the Feflow and GIS technologies. From the simulation, punning measure relatively reduces infiltration recharge and artificial gravel drain increases groundwater seepage. The basic characteristics of groundwater flow field is controlled by the old and new topographies in the whole study area, and artificial gravel drain plays an auxiliary role in accelerating groundwater drawdown upstream and promotes groundwater rise downstream. According to differences of groundwater level and declining percentages of hydraulic gradient in the main and secondary gullies, dewatering of artificial gravel drain in the secondary gully is more effective than that in the main gully, which will yet play an important role in the future. The study results will make contributions to understand groundwater response to land creation engineering and will be beneficial to take necessary measures to prevent collapse of loess and failure of building foundation in the hilly and gully area of the Loess Plateau.  相似文献   

Numerical Analysis of Gravity Coring Using Coupled Eulerian-Lagrangian Method and a New Corer     

Huawei Qin  Zhen Cai  Jianjun Wang  Wei Ye  Ying Chen 《Marine Georesources & Geotechnology》2016,34(5):403-408

The shortcomings of gravity corers in sampling marine sediments have been observed extensively in various field tests. In order to optimize the coring, this article provides an alternative numerical way to model the gravity coring and analyze the sampling effect. Based on this analysis, a new hydraulic hammer corer is devised. A coupled Eulerian-Lagrangian method with capability of simulating the problem involving extreme deformation, penetration is used to simulate the coring process. The results show that the hydrostatic pressure and deviator stress increase and reach their peak when the pile tip is slightly above or at the level of the observation point and then drop rapidly when the pile tip slides below the observation point. In addition, the stress path indicates that the soil element sustains plastic compression before yielding and then expands until recovering to the original state. The obvious “under-sampling” phenomenon is also well-captured by the finite element model.  相似文献   

Evaluation of Effective Depth of PVD Improvement in Soft Clay Deposit: A Field Case Study     

Jun Chen  Zhen-Yu Yin  Ye-Shuang Xu  Suksun Horpibulsuk 《Marine Georesources & Geotechnology》2016,34(5):420-430

This article presents a case history of determination of effective depth of prefabricated vertical drains (PVDs) under embankment loading on a very soft clay deposit in central China, near Jiujiang, Jiangxi Province. The height of the embankment was 5.3 m and construction time was about one year. The PVDs were installed to a depth of 8.5 m at a spacing of 1.5 m in a triangular pattern. Field observations and the finite element method (FEM) were employed to analyze the performance of the soft deposit during embankment construction. The influential depth of the embankment loading was evaluated based on settlement, excess pore pressure, and stress increase in subsoil, both from the observed data and FEM analysis. The effective PVD depth was determined in the following ways: (1) the depth of 5% subsoil settlement of surface settlement; (2) vertical stress increase in subsoil of 25% in-situ stress; and (3) consolidation time/PVD depth relation by FEM. Based on the analysis, the effective depth of PVDs was determined to be between 10 and 12.8 m for this field case.  相似文献   

The Sediment Source and Transport Trends around the Abandoned Yellow River Delta,China     

Lin Zhang  Shenliang Chen  Liang Yi 《Marine Georesources & Geotechnology》2016,34(5):440-449

Sediment source and transport trends are influenced by various hydrodynamic factors, and thus play important roles in sedimentary evolution and coastal stability. To examine sediment transport trends around the abandoned Yellow River delta promontory and its erosion mechanism, we employ empirical orthogonal function (EOF) analysis to study sedimentary characteristics and transport trends of the abandoned Yellow River delta in northern Jiangsu Province, China. The results showed that: (1) the main sediment source in the abandoned Yellow River delta is the submarine coastal slope and both sides of the abandoned Yellow River Delta; (2) the main hydrodynamics controlling sediment transport is the current that runs along the shore, coupled with waves, especially southward currents; (3) the sediment of the study area was redistributed under hydrodynamics; coarse sediments were eroded and broadly transported to the south. Therefore, it is concluded that the sediment sources and transport have important influence on coastal evolution: the sediment source area shows mass loss of deposits and erosion; deposits in the submarine coastal slope provide the source and were continuously eroded to provide materials to other places as a sediment source.  相似文献   

Soil phosphorus composition and phosphatase activities along altitudes of alpine tundra in Changbai Mountains,China   总被引：1，自引：0，他引：1  

Xiaozhu Yang  Kai Wei  Zhenhua Chen  Lijun Chen 《中国地理科学(英文版)》2016,26(1):90-98

Alpine tundra ecosystems have specific vegetation and environmental conditions that may affect soil phosphorus(P) composition and phosphatase activities. However, these effects are poorly understood. This study used Na OH-EDTA extraction and solution31 P nuclear magnetic resonance(NMR) spectroscopy to determine soil P composition and phosphatase activities, including acid phosphomonoesterase(Ac P), phosphodiesterase(PD) and inorganic pyrophosphatase(IPP), in the alpine tundra of the Changbai Mountains at seven different altitudinal gradients(i.e., 2000 m, 2100 m, 2200 m, 2300 m, 2400 m, 2500 m, and 2600 m). The results show that total P(TP), organic P(OP), OP/TP, Na OH-EDTA extracted P and AcP, PD, and IPP activities over the altitude range of 2500–2600 m are significantly lower than those below 2400 m. The dominant extracted form of P is OP(73%–83%) with a large proportion of monoesters(65%–72%), whereas inorganic P is present in lower proportions(17%–27%). The activity of Ac P is significantly positively correlated with the contents of soil OP, total carbon(TC), total nitrogen(TN), and TP(P 0.05), indicating that the Ac P is a more sensitive index for responding P nutrient storage than PD and IPP. Soil properties, P composition, and phosphatase activities decrease with increased altitude and soil p H. Our results indicate that the distribution of soil P composition and phosphatase activities along altitude and Ac P may play an important role in P hydrolysis as well as have the potential to be an indicator of soil quality.  相似文献   

Variation of Thornthwaite moisture index in Hengduan Mountains,China   总被引：2，自引：1，他引：1  

Guofeng Zhu  Dahe Qin  Huali Tong  Yuanfeng Liu  Jiafang Li  Dongdong Chen  Kai Wang  Pengfei Hu 《中国地理科学(英文版)》2016,26(5):687-702

The Thornthwaite moisture index, an index of the supply of water(precipitation) in an area relative to the climatic demand for water(potential evapotranspiration), was used to examine the spatial and temporal variation of drought and to verify the influence of environmental factors on the drought in the Hengduan Mountains, China. Results indicate that the Thornthwaite moisture index in the Hengduan Mountains had been increasing since 1960 with a rate of 0.1938/yr. Annual Thornthwaite moisture index in Hengduan Mountains was between –97.47 and 67.43 and the spatial heterogeneity was obvious in different seasons. Thornthwaite moisture index was high in the north and low in the south, and the monsoon rainfall had a significant impact on its spatial distribution. The tendency rate of Thornthwaite moisture index variation varied in different seasons, and the increasing trends in spring were greater than that in summer and autumn. However, the Thornthwaite moisture index decreased in winter. Thornthwaite moisture index increased greatly in the north and there was a small growth in the south of Hengduan Mountains. The increase of precipitation and decrease of evaporation lead to the increase of Thornthwaite moisture index. Thornthwaite moisture index has strong correlation with vegetation coverage. It can be seen that the correlation between Normalized Difference Vegetation Index(NDVI) and Thornthwaite moisture index was positive in spring and summer, but negative in autumn and winter. Correlation between Thornthwaite moisture index and relative soil relative moisture content was positive in spring, summer and autumn, but negative in winter. The typical mountainous terrain affect the distribution of temperature, precipitation, wind speed and other meteorological factors in this region, and then affect the spatial distribution of Thornthwaite moisture index. The unique ridge-gorge terrain caused the continuity of water-heat distribution from the north to south, and the water-heat was stronger than that from the east to west part, and thus determined the spatial distribution of Thornthwaite moisture index. The drought in the Hengduan Mountains area is mainly due to the unstable South Asian monsoon rainfall time.  相似文献   

Assessing suitability of rural settlements using an improved technique for order preference by similarity to ideal solution   总被引：1，自引：1，他引：0  

Yanfang Liu  Jiaxing Cui  Xuesong Kong  Chen Zeng 《中国地理科学(英文版)》2016,26(5):638-655

Land suitability assessment is a prerequisite phase in land use planning; it guides toward optimal land use by providing information on the opportunities and constraints involved in the use of a given land area. A geographic information system-based procedure, known as rural settlement suitability evaluation (RSSE) using an improved technique for order preference by similarity to ideal solution (TOPSIS), was adopted to determine the most suitable area for constructing rural settlements in different geographical locations. Given the distribution and independence of rural settlements, a distinctive evaluation criteria system that differed from that of urban suitability was established by considering the level of rural infrastructure services as well as living and working conditions. The unpredictable mutual interference among evaluation factors has been found in practical works. An improved TOPSIS using Mahalanobis distance was applied to solve the unpredictable correlation among the criteria in a suitability evaluation. Uncertainty and sensitivity analyses obtained via Monte Carlo simulation were performed to examine the robustness of the model. Daye, a resource-based city with rapid economic development, unsatisfied rural development, and geological environmental problems caused by mining, was used as a case study. Results indicate the following findings: 1) The RSSE model using the improved TOPSIS can assess the suitability of rural settlements, and the suitability maps generated using the improved TOPSIS have higher information density than those generated using traditional TOPSIS. The robustness of the model is improved, and the uncertainty is reduced in the suitability results. 2) Highly suitable land is mainly distributed in the northeast of the study area, and the majority of which is cultivated land, thereby leading to tremendous pressure on the loss of cultivated land. 3) Lastly, 12.54% of the constructive expansion permitted zone and 8.36% of the constructive expansion conditionally permitted zone are situated in an unsuitable area, which indicates that the general planning of Daye lacks the necessary verification of suitability evaluation. Guidance is provided on the development strategy of rural settlement patches to support decision making in general land use planning.  相似文献   

Analysis of phenotypic and genetic parameters for growthrelated traits in the half smooth tongue sole, <Emphasis Type="Italic">Cynoglossus semilaevis</Emphasis>     

刘峰  李仰真  杜民  邵长伟  陈松林 《中国海洋湖沼学报》2016,34(1):163-169

Phenotypic and genetic parameters for growth-related traits in the half-smooth tongue sole, Cynoglossus semilaevis, were estimated in 22 full-sib families produced by normal and neo-male breeding stocks. As phenotypic males with female genotypes, neo-males are harmful in C. semilaevis aquaculture because they reduce overall production. The present study evaluated the difference in the growth-related traits: total length (TL), body weight (BW) and square root of body weight (SQ_BW) at the age of 570 days between normal and neo-male offspring (neo-males used as male parents). The difference in the proportion of females between normal and neo-male offspring was also assessed. Based on the linear mixed model, restricted maximum likelihood (REML) and best linear unbiased prediction (BLUP) were used to estimate various (co)variance components and estimated breeding values (EBVs) of growth-related traits. As a result, all the mean values of the three studied traits were significantly larger in normal offspring than in neo-male offspring. Additionally, the female proportion was significantly larger in normal offspring than in neo-male offspring. Heritability was 0.128±0.066 2 for TL, 0.128±0.065 5 for BW and 0.132±0.062 9 for SQ_BW, all of which were low level heritabilities. The correlation coefficients of EBVs and phenotypic values of the target traits were 0.516 for TL, 0.524 for BW and 0.506 for SQ_BW, all of which were highly significant (P <0.01). Genetic correlations among TL, BW and SQ_BW were positive high (0.921–0.969) and higher than those of phenotype (0.711–0.748), both of which had low standard errors (0.063–0.123 for genotype, and 0.010–0.018 for phenotype). Compared with normal offspring, neo-male offspring have lower breeding values for each studied trait through EBVs comparison. Therefore, neo-male offspring should not be used as broodstock in a C. semilaevis breeding programs.  相似文献   

Two new species of the genus <Emphasis Type="Italic">Cobitis</Emphasis> Linnaeus (Teleostei: Cobitidae) from southern China     

陈咏霞  隋晓云  梁娜  陈毅峰 《中国海洋湖沼学报》2016,34(3):517-525

Two new species of the genus Cobitis from southern China, C. hereromacula from the Luohe River in Guangdong Province and C. baishagensis from the Nandujiang River in Hainan Province, are described and illustrated here. C. hereromacula can be distinguished from its congeners by possessing the following combination of characteristics: absence of the second and third pigmentary zones of Gambetta; 13–16 oval blotches on the dorsum and 10–13 vertical, elongated triangular blotches below the midlateral line with more than 20 vertical dark brown bars between them; 6–7 narrow rows of dark spots on the caudal fin; a vertical oval spot smaller than the eye diameter on the upper part of the caudal peduncle; pointed mental lobes of the lower lip pointed with a slightly filiform tip; one slender and long needle-shaped lamina circularis at the base of the first branched ray of the male pectoral fins. C. baishagensis can be distinguished from its congeners by the fourth Gambetta zone being covered by 10–12 transverse elongated blotches; 4–5 narrow rows of dark spots on the caudal fin; a vertical blotch smaller than the eye diameter on the upper part of the caudal peduncle; males with a slender and long needle-shaped lamina circularis at the second branched pectoral fin ray in males; large scales with a slightly large focal zone; undeveloped mental lobes with a lower lip that does not end posteriorly in a filiform tip.  相似文献   

Enrichment characteristics and risk assessment of Hg in bird feathers from Caohai wetland in Guizhou Province,China     

Fengcheng Peng  Tianrong He  Zhenji Li  Mengyu Chen  Xiaoli Qian  Lingxia Zeng  Yiyuan Xu 《中国地球化学学报》2018,37(4):526-536

Based on the analysis of the enrichment characteristics of Hg and MeHg in bird feathers from Caohai National Nature Reserve in Guizhou, the risks of Hg pollution to the birds from Caohai wetland have been evaluated. The total Hg content of bird feathers ranges from 40 to 5058 ng/g with an average of 924 ng/g. The content of MeHg is significantly correlated with total Hg (r = 0.68, p < 0.01), and the content are among 0.75 and 113 ng/g. The total Hg content in the birds feathers is significantly dependent on their feeding habits, which is mainly in accordance with the following rule: carnivorous birds > omnivorous birds that are mainly carnivorous > omnivorous birds that are mainly herbivorous. There are also differences in the Hg enrichment ability in the different parts of bird feathers, and the total Hg and MeHg content in the wing feathers are significantly higher than that in the other parts of feathers. The bioaccumulation coefficients of aqueous Hg and MeHg by bird feathers are 0.9 × 10⁴–112.13 × 10⁴ (mean value is 20.47 × 10⁴) and 0.47 × 10⁴–70.4 × 10⁴ (mean value is 9.52 × 10⁴), respectively. Although the whole Hg level in Caohai bird feathers is not too high, the Hg content in some carnivorous birds exceeds over or approaches the abnormal threshold when birds are breeding (5 μg/g), which indicates that the birds in Caohai wetland are faced with some risks of ecological Hg pollution.  相似文献