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Journal Articles

Numeral simulation of longitudinal river profile considering fluvial sediment transportation

Tanikawa, Shinichi; Sanga, Tomoji*; Yasue, Kenichi

Chikei, 37(2), p.189 - 207, 2016/04

JP, 2009-239446   Patent publication (In Japanese)

Existing simulation methods of long-term fluvial processes, represented as conventional difference scheme of diffusion equation, cannot control about the expression of sediment transportation satisfactorily, particularly around confluences in middle and lower reach of the river. To address this, we newly developed a numeral model and simulation program of fluvial processes, in which sediment outflux is distributed to multiple grids with the formula that enlarges the fluvial transport efficiency downstream as a function of grain-size and drainage area (named "transport distance increment curve"). This formula can control the concavity of longitudinal profile. With this model, analyses about expressions of geomorphic development in longitudinal river profile were carried out. As a result, it was confirmed that, with accurate settings of parameters, this model can yield features of river profiles, considering sediment transportation around confluences. It is believed from the above that this model enables the expression of fluvial topography as seen in nature, by translating the concept of long-term fluvial process into parameters.

Journal Articles

Modeling geomorphic changes in sedimentary rock areas; A Case study in the Boso peninsula area, Central Japan

Hanatani, Ikuo; Munakata, Masahiro; Kimura, Hideo; Sanga, Tomoji*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 18(1), p.3 - 23, 2011/06

Evaluation of the radionuclide migration toward the human environment associated with groundwater flow is an issue of importance in safety assessment of geological disposal. We constructed models depicting the influences of geomorphological evolution on long-term groundwater flow. This was done by reconstructing the processes of river deepening with historical simulation of the profiles of four rivers in the Boso Peninsula. The study resulted in the sum of erosion during the past 125,000 years which is the equivalent of one glacial to interglacial cycle. The profiles of four rivers during the last glacial age to the present were successfully reconstructed using similar parameters. It was found that the profiles were sculpted in accordance with the uplifting rates with very little influence of initial topography owing to the relatively soft and easily dissected characteristics of the geological units.

Journal Articles

An Analytic investigation of periglacial topography in Horonobe region, Hokkaido

Hanatani, Ikuo; Munakata, Masahiro; Kimura, Hideo; Sanga, Tomoji*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 17(2), p.55 - 70, 2010/12

We conducted a study on key factors regarding changes of groundwater flow from the last glacial to the postglacial stages in the Horonobe. Specifically, geomorphological analysis was carried out using aerial photographs and a high resolution (10 m) DEM to obtain the distribution of the slopes that had been formed after the last glacial stage, and the erosion depth of those slopes was analyzed. The results are summarized as follows: (1) Although periglacial smooth slopes which expanded widely in Horonobe region over the last glacial stage were eroded by rainfall increase and steeper slopes had been formed in the postglacial stage, this postglacial erosion is not uniform and is strongly influenced by the geology. (2) The drainage density is low and less than 40% of periglacial smooth slopes have been eroded to the present in the Koetoi and Wakkanai Formations while it is high and 60% or more of those slopes have already been eroded in the Yuchi and Sarabetsu Formations.

Journal Articles

Simulation of the longitudinal river profile

Sanga, Tomoji*; Yasue, Kenichi

Chikei, 29(1), p.27 - 49, 2008/01

We will first show in this paper that the longitudinal river profile can be estimated by model simulation. Then the results of application of similar algorithm to an actual river profile will be laid out. Also the results of application to a number of river profiles will be reported. Also it will be shown that the erosion process varies with rivers, particularly the location of the erosional front varied considerably. This difference of erosional process can be explained by the distribution of geologic units, and thus the past changes of topographic features can be reproduced by this simulation.

JAEA Reports

Estimation of the crustal deformation by using Differential Interferometric SAR (Synthetic Aperture Radar) data

Sanga, Tomoji*

JNC TJ5400 2004-005, 130 Pages, 2005/03

JNC-TJ5400-2004-005.pdf:18.55MB

The Teshio Plain is considered as a subsidence area during the Quaternary period. This work is estimation of the amounts of crustal deformation in the plain by using Differential Interferometric SAR (Synthetic Aperture Radar) data and is assessing the capability of the technique for estimation of crustal deformation by using SAR data.

JAEA Reports

None

Sanga, Tomoji*

JNC TJ5410 2005-006, 159 Pages, 2005/02

JNC-TJ5410-2005-006.pdf:31.06MB

Crustal deformation until the present in the Northern Hokkaido including Horonobe Town, concomitant changes of geological environments and arising earthquake have been nvestigated as the Horonobe underground research laboratory project. As a part of this project, two surveys were performed to elucidate fracture systems in an area including the Horonobe Town:(1)}Interpretation of lineament, Filed survey for fault and fracture(2)}Investigation for eruption history by the RIPL method (This survey is intended for the terrace deposit distributing around the Omagari Fault.)The lineaments, which was recognized by the interpretation and automatically extracted, have common characteristics on the point of direction and density. In the Koetoi and Wakkanai Formation, the peculiar characteristic of fracture is similar. But, the density of lineament in the latter was almost twice as much as that in the former. In the drill hole near the Omagari Fault, there is a group of fractures crossing the bedding plane. By the comparison with the data of this group, lineaments show similar characteristics on the point of direction, density and dip. So, it is considered that the lineaments reflect this group of actures. When the changes on the peculiar characteristic of lineaments and fractures in drill hole are examined, the density of fractures in the hanging side is higher than that in the footwall. In the west side of the fault, the direction of lineament greatly changes on the border almost 400m away from the fault. So, it is estimated that the range of fluence of the fault is up to this border.The investigation of eruption history was performed at the seven points. As a result of this investigation, it became clear that MIS5c and MIS5e in the Atras of Quaternary Marine Terraces (2001) correspond MIS7 and MIS9 respectively and the velocity of uplift decreases to 1/3 compared with that onsidered so far.

JAEA Reports

None

Sanga, Tomoji*

JNC TJ7420 2005-096, 262 Pages, 2004/03

JNC-TJ7420-2005-096.pdf:83.18MB

The simulation programs were executed between 120,000 yaers at the Hashikami and Tono region.

JAEA Reports

Automatical Extraction of Lineaments from Hi-Resolution DEM

Sanga, Tomoji*

JNC TJ7420 2005-091, 159 Pages, 2004/03

JNC-TJ7420-2005-091.pdf:38.76MB

In this study, we developed a method to detect lineaments automatically through statistic features calculated from DEM with reference to topographical features observed around lineaments extracted by photo interpretation.

JAEA Reports

A Study of Lineaments in the Tono Area

Sanga, Tomoji*

JNC TJ7420 2005-053, 176 Pages, 2004/03

Various parameters are examined as liniaments detected by this method coincide with ones extracted by photo interpretation.

JAEA Reports

A Study of Lineaments in the Horonobe Area

Sanga, Tomoji*

JNC TJ5420 2004-001, 160 Pages, 2004/03

JNC-TJ5420-2004-001.pdf:43.1MB

Crustal deformation until the present in the Northern Hokkaido including Horonobe Town, concomitant change of geological environments and arising earthquake have been investigated as the Horonobe underground research laboratory project. This lineament study was performed to elucidate fracture systems in an area including Horonobe Town as a part of these projects.

JAEA Reports

None

Sanga, Tomoji*

JNC TJ7420 2005-084, 321 Pages, 2003/03

JNC-TJ7420-2005-084.pdf:80.69MB

The simulation programs were executed between 120,000 years at Hashikami region, catchments area of the Hiyoshi river and the Toki river.

JAEA Reports

None

Sanga, Tomoji*

JNC TJ7420 2005-082, 271 Pages, 2002/03

JNC-TJ7420-2005-082.pdf:54.18MB

Erosion and transportation of the substance which forms geographical feature are expressed with a diffusion equation as the thoretical foundation of a simulation.

JAEA Reports

None

Sanga, Tomoji*

JNC TJ7420 2005-081, 80 Pages, 2002/03

JNC-TJ7420-2005-081.pdf:19.9MB

We discuss characteristics of geographical features and a basin besides rivers at Tono using DEM.

JAEA Reports

Regional distribution of erosion rates over the Japanese Islands

Fujiwara, Osamu; Sanga, Tomoji*; Omori, Hiroo*

JNC TN7410 2001-015, 29 Pages, 2001/08

JNC-TN7410-2001-015.pdf:1.49MB
JNC-TN7410-2001-015-appendix(CD-ROM).zip:2.07MB

Regional distribution of erosion rates has been studied to clarify the long-term stability of the geological environment in Japan. The regional distribution of erosion rates should be estimated to predict long-term geomorphological changes. This research is to estimate the distribution of erosion rates over the Japanese Islands based on the relationship between the sediment delivery rates to reservoirs and the dispersion of altitude of the drainage basins. The relationship between erosion rate E(mm/y) and dispersion of altitude D(m) of drainage basins is expressed by E=0.000044 D$$^{2.2}$$ with a correlation coefficient of 0.94. This equation was used to calculate the denudation rate for each 6 km $$times$$ 6 ㎞ area of the Japanese Islands using a "digital map 50 m grid". The denudation rates are, highest in the central Japanese mountains ($$leqq$$ 3-5 mm/y), moderate in the outer belt of Southwest Japan, the inner belt of Northeast Japan and Hokkaido ($$leqq$$ 2-3 mm/y), and lowest in the inner belt of Southwest Japan, outer belt of Northeast Japan and central Hokkaido ($$leqq$$ 1 mm/y). These regional characteristics are closely related to the distribution of Quaternary uplift rates, which caused the regional differences in surface topography.

JAEA Reports

None

Sanga, Tomoji*

JNC TJ7420 2005-083, 186 Pages, 2001/03

JNC-TJ7420-2005-083.pdf:29.95MB

None

Journal Articles

Regional distribution of erosion rates over the Japanese Islands

Fujiwara, Osamu; Sanga, Tomoji*; Omori, Hiroo*

Saikuru Kiko Giho, (5), p.85 - 93, 1999/12

None

JAEA Reports

None

Sanga, Tomoji*

JNC TJ7420 2005-005, 63 Pages, 1999/03

JNC-TJ7420-2005-005.pdf:10.35MB

no abstracts in English

JAEA Reports

None

Sanga, Tomoji*

JNC TJ7420 2005-093, 361 Pages, 1999/02

JNC-TJ7420-2005-093.pdf:65.12MB

no abstracts in English

Oral presentation

Simulation of longitudinal river profile in consideration of bedrock

Yasue, Kenichi; Sanga, Tomoji*; Nogami, Michio*; Tajikara, Masayoshi; Niizato, Tadafumi

no journal, , 

This paper presents the results of simulation of longitudinal river profile. Fast, we show that the longitudinal river profile is simulated in simplified model. Next, we simulated actual rivers by the same algorithm as the simplified model. This simulation shows that erosion rate and position of erosional front are different in each river. We think that Lithology influence the difference of erosional process in the river profile.

Oral presentation

Hydrological estimation of fractures in the crystalline terrain by utilizing lineament extraction and natural $$gamma$$-ray detection

Hanatani, Ikuo; Munakata, Masahiro; Kimura, Hideo; Sanga, Tomoji*

no journal, , 

In Japan Atomic Energy Agency, surveillance studies are currently underway with the aims of establishing the evaluation system of a groundwater flow for a regional scale over long periods and verifying a hydrologic groundwater flow model with survey data etc. As part of these studies, the lineament extraction and natural $$gamma$$-ray detection were conducted in two granite distribution regions in order to estimate the distribution of fractures and the hydrogeological structure at the crystalline terrain in a mountain area deficient in the existing information such as a drilling investigation. This report describes the result of combinatorial utilization of lineament extraction and natural $$gamma$$-ray detection.

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