A pragmatic analysis of water supply and demand,and adaptive capacity in rural areas: development of Rural Water Insecurity Index     

Mrittika Basu  Satoshi Hoshino  Shizuka Hashimoto 《Natural Hazards》2016,81(1):447-466

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Numerical analysis on seepage failures of dike due to water level-up and rainfall using a water–soil-coupled smoothed particle hydrodynamics model     

Weijie Zhang  Kenichi Maeda  Hiroshi Saito  Zhaoqing Li  Yu Huang 《Acta Geotechnica》2016,11(6):1401-1418

For seepage failures of dike due to water level-up and rainfall, surface infiltration and strength change induced by suction reduction are important factors; thus, numerical analysis should consider the coupling of water and soil, as well as the effect of saturation to obtain more precise failure mechanism. Based on the advanced smoothed particle hydrodynamics (SPH) method, this work proposed a two-phase-coupled SPH model in coordination with a novel constitutive model for unsaturated soils. Then, a triaxial compression test is simulated to check the applicability of the SPH method on the soil phase. After that, the failure test of a dike due to water level-up is discretized and simulated, from which the seepage process, the distribution of maximum shear strain, the slip surface, and pore water pressure are obtained. The two-phase-coupled SPH model is also applied to a slope failure test of heavy rainfall, and the results are compared to the model test. Finally, a dike failure test due to rainfall is analyzed using the proposed SPH model to reproduce the surface infiltration and suction reduction. The proposed SPH model provides several insights of seepage failures and can be a helpful tool for the analysis of dike failures induced by water level-up and rainfall.  相似文献   

Characteristic Features of REE and Pb–Zn–Ag Mineralizations in the Na Son Deposit,Northeastern Vietnam          下载免费PDF全文

Can Pham‐Ngoc  Daizo Ishiyama  Tuan Anh Tran  Mihoko Hoshino  Sachihiro Taguchi 《Resource Geology》2016,66(4):404-418

The Na Son deposit is a small‐scale Pb–ZnPb–Zn–Ag deposit in northeast Vietnam and consists of biotite–chlorite schist, reddish altered rocks, quartz veins and syenite. The biotite–chlorite schist is intruded by syenite. Reddish altered rocks occur as an alteration halo between the biotite–allanite‐bearing quartz veins and the biotite–chlorite schist. Allanite occurs in the biotite–allanite‐bearing quartz veins and in the proximal reddish altered rocks. Rare earth element (REE) fluorocarbonate minerals occur along fractures or at rim of allanite crystals. The later horizontal aggregates of sulfide veins and veinlets cut the earlier reddish altered rocks. The earlier Pb–Zn veins consist of a large amount of galena and lesser amounts of sphalerite, pyrite and molybdenite. The later Cu veins cutting the Pb–Zn veins include chalcopyrite and lesser amounts of tetrahedrite and pyrite. The occurrences of two‐phase H₂O–CO₂ fluid inclusions in quartz from biotite–allanite‐bearing quartz veins and REE‐bearing fluorocarbonate minerals in allanite suggest the presence of CO₂ and F in the hydrothermal fluid. The oxygen isotopic ratios of the reddish altered rocks, biotite–chlorite schist, and syenite range from +13.9 to +14.9 ‰, +11.5 to +13.3 ‰, and +10.1 to +11.6 ‰, respectively. Assuming an isotopic equilibrium between quartz (+14.6 to +15.8 ‰) and biotite (+8.6 ‰) in the biotite–allanite‐bearing quartz vein, formation temperature was estimated to be 400°C. At 400°C, δ¹⁸O values of the hydrothermal fluid in equilibrium with quartz and biotite range from +10.5 to +11.7 ‰. These δ¹⁸O values are consistent with fluid that is derived from metamorphism. Assuming an isotopic equilibrium between galena (+1.5 to +1.7 ‰) and chalcopyrite (+3.4 ‰), the formation temperature was estimated to be approximately 300°C. The formation temperature of the Na Son deposit decreased with the progress of mineralization. Based on the geological data, occurrence of REE‐bearing minerals and oxygen isotopic ratios, the REE mineralization is thought to result from interaction between biotite–chlorite schist and REE‐, CO₂‐ and F‐bearing metamorphic fluid at 400°C under a rock‐dominant condition.  相似文献   

Groundwater resources management under environmental constraints in Shiroishi of Saga plain, Japan     

Nguyen Cao Don  Nguyen Thi Minh Hang  Hiroyuki Araki  Hiroyuki Yamanishi  Kenichi Koga 《Environmental Geology》2006,49(4):601-609

A sinking of the land surface due to the pumping of groundwater has long been recognized as an environmental issue in the Shiroishi plain of Saga, Japan. Land subsidence can have several negative economic and social implications such as changes in groundwater and surface water flow patterns, restrictions on pumping in land subsidence prone areas, localized flooding, failure of well casings as well as shearing of structures. To minimize such an environmental effect, groundwater management should be considered in this area. In this study, a new integrated numerical model that integrates a three-dimensional numerical groundwater flow model coupled with a one-dimensional soil consolidation model and a groundwater optimization model was developed to simulate groundwater movement, to predict ground settlement and to search for optimal safe yield of groundwater without violating physical, environmental and socio-economic constraints. It is found that groundwater levels in the aquifers greatly vary from season to season in response to the varying climatic and pumping conditions. Consequently, land subsidence has occurred rapidly throughout the area with the Shiroishi plain being the most prone. The predicted optimal safe yield of the pumping amount is about 5 million m³. The study also suggests that pumping with this optimal amount will minimize the rate of land subsidence over the entire area. An erratum to this article can be found at  相似文献   

A Possible Role of Boiling in Ore Deposition: A Numerical Approach   总被引：2，自引：0，他引：2  

Kenichi Hoshino    Tom Itami    Ryouta Shiokawa  Makoto Watanabe 《Resource Geology》2006,56(1):49-54

Abstract. A possible role of boiling of the H₂O-NaCl-CO₂(-H₂S) fluid in ore deposition has been examined numerically by using the equations of state (EOS) of Duan et al. (1995, 1996), a modified EOS of Bowers and Helgeson (1983) and the water-rock interaction simulator MIX99 (Hoshino et al., 2000).
The following three models are examined to evaluate an efficiency of boiling on mineral precipitation: (1) hypothetical non-boiling process, (2) hypothetical boiling process with sulfur partitioned only in liquid phases and (3) boiling process in which partition ratios of H₂S between liquid and vapor phases are assumed to be the same as those of CO₂. The processes are simulated from 450C and 900 bar to 310C and 620 bar with an analytical step of 10C / 20 bar. Boiling occurs below 400C in the latter two processes when the initial composition (in mole fraction) of the fluid is: X_H2o = 0.84, X_NaC1 = 0.10 and X_Co2 = 0.06.
Ore deposition occurs abruptly at a boiling point when the partition ratios of total sulfur (X_s^vap/X_s^liq) are as high as those of total carbon during boiling. A decrease of concentration of sulfur in the liquid phase during boiling leads to an increase of pH of the solution, resulting in propelling mineral precipitation. It has been made clear that a possible role of boiling in ore formation mainly depends on the partition ratios of sulfur between the liquid and vapor phases, although they cannot be estimated accurately by the currently available EOS.  相似文献   

Phase transition of zircon at high P-T conditions     

Shigeaki?OnoEmail author  Kenichi?Funakoshi  Yoichi?Nakajima  Yoshinori?Tange  Tomoo?Katsura 《Contributions to Mineralogy and Petrology》2004,147(4):505-509

Abstract In situ observations of the zircon-reidite transition in ZrSiO₄ were carried out using a multianvil high-pressure apparatus and synchrotron radiation. The phase boundary between zircon and reidite was determined to be P (GPa) = 8.5+0.0017×(T-1200) (K) for temperatures between 1100–1900 K. When subducted slabs, including igneous rocks and sediments, descend into the upper mantle, the zircon in the subducted slab transforms into reidite at pressures of about 9 GPa, corresponding to a depth of 270 km. Reidite found in an upper Eocene impact ejecta layer in marine sediments is thought to have been transformed from zircon by a shock event. The peak pressure generated by the shock event in this occurrence is estimated to be higher than 8 GPa.Editorial responsibility: J. Hoefs  相似文献   

Simulation of groundwater flow and environmental effects resulting from pumping   总被引：1，自引：1，他引：1  

Nguyen Cao Don  Hiroyuki Araki  Hiroyuki Yamanishi  Kenichi Koga 《Environmental Geology》2005,47(3):361-374

In coastal lowland plains, increased water demand on a limited water resource has resulted in declining groundwater levels, land subsidence and saltwater encroachment. In southwestern Kyushu, Japan, a sinking of the land surface due to over pumping of groundwater has long been recognized as a problem in the Shiroishi lowland plain. In this paper, an integrated model was established for the Shiroishi site using the modular finite difference groundwater flow model, MODFLOW, by McDonald and Harbaugh (1988) and the modular three-dimensional finite difference groundwater solute transport model, MT3D, by Zheng (1990) to simulate groundwater flow hydraulics, land subsidence, and solute transport in the alluvial lowland plain. Firstly, problems associated with these groundwater resources were discussed and then the established model was applied. The simulated results show that subsidence rapidly occurs throughout the area with the central prone in the center part of the plain. Moreover, seawater intrusion would be expected along the coast if the current rates of groundwater exploitation continue. Sensitivity analysis indicates that certain hydrogeologic parameters such as an inelastic storage coefficient of soil layers significantly contribute effects to both the rate and magnitude of consolidation. Monitoring the present salinization process is useful in determining possible threats to fresh groundwater supplies in the near future. In addition, the integrated numerical model is capable of simulating the regional trend of potentiometric levels, land subsidence and salt concentration. The study also suggests that during years of reduced surface-water availability, reduction of demand, increase in irrigation efficiency and the utilization of water exported from nearby basins are thought to be necessary for future development of the region to alleviate the effects due to pumping.  相似文献   

Optimum delay interval design in delay blasting   总被引：2，自引：0，他引：2  

Tatsuya Hoshino  Gento Mogi  Kou Shaoquan 《Fragblast: International Journal for Blasting and Fragmentation》2000,4(2):139-148

The major concern of this research is the reduction of blast vibrations at certain points of foremost importance. A procedure for optimum delay interval design, considering detonation time errors of the electric detonators, was proposed. Using the relationship between the peak particle velocity (PPV) and the delay at certain points of interest which was calculated by means of a computer program by simulating the superposition of the vibration waves emitted from each borehole, one can usually select the optimal delay interval in order to minimize the PPV. But due to the variations in the actual delay caused by the detonation time errors, the expected PPV usually not only depends on the nominal delay but also on the sensitivity of the PPV. Therefore, the selection of the optimum time interval for a delay blast should be based on both the optimum as well as several sub-optimal time intervals as candidates. In addition, the detonation time errors should be taken into consideration. Also, a new design concept, called 'combined delay blasting', which uses electronic detonators, is proposed to further reduce the PPV at the points of interest. Estimated vibration time histories based on this concept and their PPVs indicated considerably favorable results.  相似文献   

Towards a diagnostic approach to climate adaptation for fisheries     

P. Leith  E. Ogier  G. Pecl  E. Hoshino  J. Davidson  M. Haward 《Climatic change》2014,122(1-2):55-66

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Impacts of different diffusion scenarios for mitigation technology options and of model representations regarding renewables intermittency on evaluations of CO2 emissions reductions     

Fuminori Sano  Keigo Akimoto  Kenichi Wada 《Climatic change》2014,123(3-4):665-676

This paper evaluated the impacts of climate change mitigation technology options on CO₂ emission reductions and the effects of model representations regarding renewable intermittency on the assessment of reduction by using a world energy systems model. First, different diffusion scenarios for carbon dioxide capture and storage (CCS), nuclear power, and wind power and solar PV are selected from EMF27 scenarios to analyze their impacts on CO₂ emission reductions. These technologies are important for reducing CO₂ intensity of electricity, and the impacts of their diffusion levels on mitigation costs are significant, according to the analyses. Availability of CCS in particular, among the three kinds of technologies, has a large impact on the marginal CO₂ abatement cost. In order to analyze effects of model representations regarding renewables intermittency, four different representations are assumed within the model. A simplistic model representation that does not take into consideration the intermittency of wind power and solar PV evaluates larger contributions of the energy sources than those evaluated by a model representation that takes intermittency into consideration. Appropriate consideration of renewables intermittency within global energy systems models will be important for realistic evaluations of climate change mitigation scenarios.  相似文献