A physically based distributed subsurface–surface flow dynamics model for forested mountainous catchments     

Deogratias M. M. Mulungu  Yutaka Ichikawa  Michiharu Shiiba 《水文研究》2005,19(20):3999-4022

This study was designed to develop a physically based hydrological model to describe the hydrological processes within forested mountainous river basins. The model describes the relationships between hydrological fluxes and catchment characteristics that are influenced by topography and land cover. Hydrological processes representative of temperate basins in steep terrain that are incorporated in the model include intercepted rainfall, evaporation, transpiration, infiltration into macropores, partitioning between preferential flow and soil matrix flow, percolation, capillary rise, surface flow (saturation‐excess and return flow), subsurface flow (preferential subsurface flow and baseflow) and spatial water‐table dynamics. The soil–vegetation–atmosphere transfer scheme used was the single‐layer Penman–Monteith model, although a two‐layer model was also provided. The catchment characteristics include topography (elevation, topographic indices), slope and contributing area, where a digital elevation model provided flow direction on the steepest gradient flow path. The hydrological fluxes and catchment characteristics are modelled based on the variable source‐area concept, which defines the dynamics of the watershed response. Flow generated on land for each sub‐basin is routed to the river channel by a kinematic wave model. In the river channel, the combined flows from sub‐basins are routed by the Muskingum–Cunge model to the river outlet; these comprise inputs to the river downstream. The model was applied to the Hikimi river basin in Japan. Spatial decadal values of the normalized difference vegetation index and leaf area index were used for the yearly simulations. Results were satisfactory, as indicated by model efficiency criteria, and analysis showed that the rainfall input is not representative of the orographic lifting induced rainfall in the mountainous Hikimi river basin. Also, a simple representation of the effects of preferential flow within the soil matrix flow has a slight significance for soil moisture status, but is insignificant for river flow estimations. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Near-Infrared Photometric And Polarimetric Observations Of Comet Hale-Bopp     

Hitoshi Hasegawa  Takashi Ichikawa  Shinsuke Abe  Shiomo Hamamura  Koji Ohnishi  Jun-Ich Watanabe 《Earth, Moon, and Planets》1997,78(1-3):353-358

Near-infrared photometric and polarimetric observations of comet Hale-Bopp (1995 O1) using KONIC (Kiso Observatory Near-Infrared Camera) are reported. Observations were carried out on March 18 UT and April 26 UT 1997, when the heliocentric distances of the comet were 0.94 and 1.02 AU, and the phase angles were 48.5 deg and 32.9 deg, respectively. In the J, H, and K′ bands, we obtained linear polarization of the near-nucleus region of 16.4 ± 1.2, 18.8 ± 1.3, and 15.1 ± 0.9 percent on March 18UT and 7.1 ± 1.1, 8.9 ± 1.0, and 6.9 ± 0.6 percent on April 26, respectively. These values were higher than those observed for 1P/Halley. The maximum polarization was found at H band on both dates. Polarization maps showed higher polarization regions toward the anti-solar direction in the J and H bands. No distinct correlation was found between high polarization regions and bright regions. The projected expansion velocity of the arc structure of the dust jet was 375 ± 35.7 m/s on 17–19 March. The periodicity was found to be 11.1 ± 2.8 hours. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Deformation and fracturing behaviour of discontinuous rock mass and damage mechanics theory     

Toshikazu Kawamoto  Yasuaki Ichikawa  Takashi Kyoya 《国际地质力学数值与分析法杂志》1988,12(1):1-30

The mechanical behaviour of a rock mass is strongly affected by discontinuities such as faults and joints. In this paper, a damage mechanics theory is proposed which deals with some sets of discontinuities distributed in a rock mass, for example, joint systems. In this theory, the distributed discontinuities are characterized by a second-order symmetric tensor, called the damage tensor. By introducing the damage concept, the deformation and fracturing behaviour of the rock mass can be reated in a framework of continuum mechanics. A numerical procedure is developed in order to implement the damage mechanics model by using the finite element method. The theory and numerical analysis are applied to several laboratory tests and a practical underground opening problem. Numerical results are compared with measured data.  相似文献   

Adsorption Characteristics of Reactive Black 5 from Aqueous Solution onto Chitosan     

Tapan K. Saha  Nikhil C. Bhoumik  Subarna Karmaker  Mahmooda G. Ahmed  Hideki Ichikawa  Yoshinobu Fukumori 《洁净——土壤、空气、水》2011,39(10):984-993

Adsorption of reactive black 5 (RB5) from aqueous solution onto chitosan was investigated in a batch system. The effects of solution pH, initial dye concentration, and temperature were studied. Adsorption data obtained from different batch experiments were modeled using both pseudo first‐ and second‐order kinetic equations. The equilibrium adsorption data were fitted to the Freundlich, Tempkin, and Langmuir isotherms over a dye concentration range of 45–100 µmol/L. The best results were achieved with the pseudo second‐order kinetic and Langmuir isotherm equilibrium models, respectively. The equilibrium adsorption capacity (q_e) was increased with increasing the initial dye concentration and solution temperature, and decreasing solution pH. The chitosan flakes for the adsorption of the dye was regenerated efficiently through the alkaline solution and was then reused for dye removal. The activation energy (E_a) of sorption kinetics was estimated to be 13.88 kJ/mol. Thermodynamic parameters such as changes in free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) were evaluated by applying the van't Hoff equation. The thermodynamics of reactive dye adsorption by chitosan indicates its spontaneous and endothermic nature.  相似文献   

Origin of near-surface high-salinity water observed in the Kuroshio Extension region     

Akira Nagano  Kazuyuki Uehara  Toshio Suga  Yoshimi Kawai  Hiroshi Ichikawa  Meghan F. Cronin 《Journal of Oceanography》2014,70(4):389-403

Hydrographic data in the Kuroshio Extension (KE) region from 2008 to 2010 show large year-to-year variability in near-surface salinity, including a very large anomalous event in February 2010. During this event, the deep winter mixed layer in the southern KE region had higher salinity than had existed during the previous summer in September 2009. Our analysis shows that advection from the Philippine Sea along the western branch of the North Pacific subtropical gyre, taking approximately 9 months, resulted in this large salinity anomaly in February 2010 and contributes to the interannual salinity variability in the southern KE region.  相似文献   

Multiple temporal scale variability during the twentieth century in global carbon dynamics simulated by a coupled climate–terrestrial carbon cycle model     

Tomomichi Kato  Akihiko Ito  Michio Kawamiya 《Climate Dynamics》2009,32(7-8):901-923

A coupled climate–carbon cycle model composed of a process-based terrestrial carbon cycle model, Sim-CYCLE, and the CCSR/NIES/FRCGC atmospheric general circulation model was developed. We examined the multiple temporal scale functions of terrestrial ecosystem carbon dynamics induced by human activities and natural processes and evaluated their contribution to fluctuations in the global carbon budget during the twentieth century. Global annual net primary production (NPP) and heterotrophic respiration (HR) increased gradually by 6.7 and 4.7%, respectively, from the 1900s to the 1990s. The difference between NPP and HR was the net carbon uptake by natural ecosystems, which was 0.6 Pg C year^?1 in the 1980s, whereas the carbon emission induced by human land-use changes was 0.5 Pg C year^?1, largely offsetting the natural terrestrial carbon sequestration. Our results indicate that monthly to interannual variation in atmospheric CO₂ growth rate anomalies show 2- and 6-month time lags behind anomalies in temperature and the NiNO₃ index, respectively. The simulated anomaly amplitude in monthly net carbon flux from terrestrial ecosystems to the atmosphere was much larger than in the prescribed air-to-sea carbon flux. Fluctuations in the global atmospheric CO₂ time series were dominated by the activity of terrestrial vegetation. These results suggest that terrestrial ecosystems have acted as a net neutral reservoir for atmospheric CO₂ concentrations during the twentieth century on an interdecadal timescale, but as the dominant driver for atmospheric CO₂ fluctuations on a monthly to interannual timescale.  相似文献   

Preliminary results of the Japan-Taiwan joint survey on combining ocean radar data in the Kuroshio upstream region     

Kaoru Ichikawa  Wen Chang Yang  Akihiko Morimoto  Yutaka Yoshikawa  Shigeo Sugitani  Wen-Shan Chiang  Jian-Wu Lai  En Yu Liang  Cho-Teng Liu  Chang-Wei Lee  Kei Yufu  Moeto Kyushima  Satoshi Fujii  Tomoharu Senju  Yoshihiko Ide 《Ocean Science Journal》2013,48(1):141-148

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An analysis method for elastic waves propagation in material involving cracks     

Sixiong Han  Yasuaki Ichikawa  Toshikazu Kawamoto 《Soil Dynamics and Earthquake Engineering》1991,10(6)

In this paper, a new model to treat the problem of elastic wave travelling in rock mass that embeds cracks is proposed, in which, instead of modelling the crack directly the mechanical effects of discontinuities are translated into the equivalent nodal forces on a numerical procedure. Thus the response is physically obtained as the superposition of the incident wave field and the scattering wave field produced by the radiation of the reflected waves from the crack surfaces. Finally, a numerical example is carried out and it shows that the results by the proposed method have a very good agreement with those of the exact ones.  相似文献   

青海海北高寒草甸五种植被生物量及环境条件比较   总被引：11，自引：4，他引：11  

李英年  赵新全  王勤学  古松  杜明远  加藤知道  王启兰  赵亮 《山地学报》2003,21(3):257-264

分析了高寒草甸不同植被类型植物种类组成、生物量变化规律及其差异。研究表明不同植被类型的分布与土壤湿度和温度有很大的关系。藏篙草草甸、金露梅灌丛草甸、矮篙草草甸、正恢复的矮篙草草甸、小嵩草草甸这5种不同植被类型所对应的土壤湿度依次降低，而所对应的土壤温度依次升高；植物种类数量表现为矮嵩草草甸＞金露梅灌丛草甸＞小篙草草甸＞正恢复的矮篙草草甸＞藏篙草草甸。地上生物量高低依次为小嵩草革甸＞矮嵩草草甸＞金露梅灌丛草甸＞正恢复的矮篙草草甸＞藏篙草草甸；地下生物量则表现出金露梅灌丛革甸＞矮嵩草甸＞小篙草草甸＞正恢复的矮篙草草甸的特征，而其在年内的周转值表现出金露梅灌丛草甸＞正承复的矮嵩草草甸＞小篙草草甸＞矮篙草草甸;土壤有机质的季节变化表现为0—40cn整层土壤有机质含量小嵩草草甸＞金露梅灌丛草甸＞矮嵩草草甸＞正恢复的矮篙草草甸，0—10cm的表层土壤有机质金露梅灌丛草甸＞矮嵩草草甸＞小嵩草草甸＞正恢复的矮篙草草甸。  相似文献   

A 100 m laser strainmeter system installed in a 1 km deep tunnel at Kamioka, Gifu, Japan   总被引：1，自引：0，他引：1  

Shuzo Takemoto  Akito Araya  Junpei Akamatsu  Wataru Morii  Hideo Momose  Masatake Ohashi  Ichiro Kawasaki  Toshihiro Higashi  Yoichi Fukuda  Shinji Miyoki  Takashi Uchiyama  Daisuke Tatsumi  Hideo Hanada  Isao Naito  Souichi Telada  Nobuo Ichikawa  Kensuke Onoue  Yasuo Wada 《Journal of Geodynamics》2004,38(3-5):477

We have installed a laser strainmeter system in a deep tunnel about 1,000 m below the ground surface at Kamioka, Gifu, Japan. The system consists of three types of independent interferometers: (1) an EW linear strainmeter of the Michelson type with unequal arms, (2) an NS-EW differential strainmeter of the Michelson type with equal arms and (3) a NS absolute strainmeter of the Fabry–Perot type. These are configured in L-shaped vacuum pipes, each of which has a length of 100 m. (1) and (2) are highly sensitive (order of 10⁻¹³ strain) and have wide dynamical range (10⁻¹³–10⁻⁶). Observations with strainmeters (1) and (2) started on June 11, 2003. (3) is a new device for absolute-length measurements of the order of 10⁻⁹ of a long-baseline (100 m) Fabry–Perot cavity by the use of phase-modulated light. This third strainmeter will be ready for operation before the end of 2004. The laser source of strainmeters (1) and (2) is a frequency-doubled YAG laser with a wavelength of 532 nm. The laser frequency is locked onto an iodine absorption line and a stability of 2 × 10⁻¹³ is attained. The light paths of the laser strainmeter system are enclosed in SUS304 stainless steel pipes. The inside pressure is kept to be 10⁻⁴ Pa. Consequently, quantitative measurement of crustal strains of the order of 10⁻¹³ can be attained by employing the laser strainmeter system of (1) and (2) at Kamioka. This resolving power corresponds to that of a superconducting gravimeter. Using the laser strainmeter system, we expect to determine parameters related to fluid core resonance, core modes and core undertone as well as other geodynamic signals such as slow strain changes caused by silent earthquakes or slow earthquakes.  相似文献