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Lin Z.,Zhejiang University | Lin Z.,Geological Survey of Japan | Kaneda H.,Geological Survey of Japan | Kaneda H.,Chiba University | And 3 more authors.
Geomorphology | Year: 2013

Despite successes elsewhere in the world, 2m resolution DEMs from a standard airborne LiDAR survey failed to detect small tectonic-geomorphic features in densely-forested high-relief mountains of central Japan. Our new 0.5-m DEMs from an unprecedentedly high-resolution LiDAR survey along the Neodani Fault now reveal a number of previously unknown fault scarps as well as other hidden geomorphic features. The survey achieves a ground-return density of 6.2m-2 out of a total shot density of as much as ~12.7m-2. The main factor to gain sufficient ground returns in unfavorable conditions is a large side lap of ~70% between flight swaths, which means that any specific area in the target zone is scanned three or more times from different angles. Evaluation of DEMs with resolution from 0.25 to 10m assures that a 0.5m resolution LiDAR DEM is necessary for the detection of subtle tectonic breaks. Another key factor for complete detection of small tectonic-geomorphic features is the application of a recently developed DEM visualization "Red Relief Image Map (RRIM)", which allows mapping of all the small features with various sizes, orientations and morphology, overcoming major drawbacks of classic DEM visualizations. A very high-resolution LiDAR survey aided with RRIM visualization as used in this study provides a more reliable approach for the detailed mapping of slight active fault traces hidden under dense vegetation. © 2012 Elsevier B.V.

Suwa H.,Ritsumeikan University | Okano K.,Asia Air Survey Co. | Kanno T.,Matsumoto Sabo Office
International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction, and Assessment, Proceedings | Year: 2011

Kamikamihorizawa Creek on the slopes of Mount Yakedake, Nagano Prefecture, was selected as a monitoring site for debris flows considering a high frequency of debris flow and instrumented with monitoring equipments in 1970: eight years after the last phreatic explosion of this volcano. The monitoring system was improved by adding speedometers, stage meters, seismometers and so on, in addition to the off-line monitoring surveys on the interaction between debris flows, hillslope hydrology and slope morphology. During the last 40 years, data were obtained from 91 debris-flow events that contained more than 200 episodes of debris-flow surges. Studies from the data supplied a general concept of the debris-flows and their geomorphic effects at volcanic slopes as follows. Debris flows are triggered by a large intensity of rainfall in a short duration as much as 10 minute. Threshold of rainfall intensity for debris flows increases with time after the end of volcanic eruption, while it drastically decreases with the eruption. Three types of debris flows were found: Large flows with boulder dam without open-work structure (Type I), small flows with boulder dam with openwork structure (Type II), and small flows with boulder dam without openwork structure (Type III). Rainfall conditions were found to have controlled the difference between these types through water availability to debris flows at the source and growth reaches of debris flows. Mass and boulder focusing to the flow front are marked, and due to this focusing the flow radiates elastic waves whose energy is from the potential energy of the flow. The energy conversion efficiency from the potential energy to elasticwave energy is a magnitude of 10-3 much smaller than the efficiency for earthquake at 10-1 from the strain energy to the elastic-wave energy. Debris flows terminate in the fan leaving two types of debris-flow lobes: swollen lobes and flat lobes. Main source of the flat lobes is attributed to the Types I and III, while the swollen lobe to the Type II. It would be important to understand this concept for volcanic debris flows from its initiation to termination for the mitigation of debris-flow hazards. © 2011 Casa Editrice Université La Sapienza.

Okano K.,Asia Air Survey Co. | Suwa H.,Kyoto University | Kanno T.,Matsumoto Sabo Office
Geomorphology | Year: 2012

We analyzed rainstorm control on debris-flow magnitude and flow characteristics using the 14 sets of rainstorm and debris-flow data obtained from 1980 to 2005 at the Kamikamihorizawa Creek of Mount Yakedake. With the principal component analysis on five parameters of debris flows: frontal velocity, peak velocity, peak flow depth, peak discharge and total discharge, and with video-record of boulder-dams in motion, and the preceding rainfall intensities, we conclude that the 14 debris flows could be categorized into three groups. The flows in the first group have large hydraulic magnitude and massive and turbulent boulder-dams filled with slurry matrix. The flows in the second group have small hydraulic magnitude and boulder-dams scarcely filled with slurry matrix, and the dam is observed to alternate between stopping and starting. The flows in the third group have small hydraulic magnitude and boulder dams filled with slurry matrix. Analysis of hillslope hydrology and debris-flow data asserted that the antecedent rainfall conditions control not only the hydraulic magnitude of debris flows but also the boulder-dam features. Large rainstorms of high intensity and durations as short as 10 minutes induces fast and large storm runoff to the headwaters and the source reaches of debris flow, while rainstorms with durations as long as 24. h raises water content in the bottom deposits along the debris-flow growth reaches and generates substantial runoff from the tributaries. Classification of the three groups is done based on water availability to debris flows on the source and growth reaches at the occurrence of debris flow. © 2011 Elsevier B.V.

Iwata Y.,Asia Air Survey Co. | Fukamachi K.,Kyoto University | Morimoto Y.,Kyoto University
Landscape and Ecological Engineering | Year: 2011

Using the public survey "The Top 100 Japanese Rural Landscapes" conducted by Asahi Shimbun Newspaper Company in 2008, this study attempted to analyze public perception of rural landscapes and their cultural value. A total of 3,024 nominated sites were given coordinates and combined with land use and topographic datasets using a GIS, and classified into several landscape types using cluster analysis. Keywords that appeared frequently in the nominations were extracted using a text-mining tool and used to interpret the cultural value of each type. As a result, the nominated sites were divided into six types. The majority of nominated sites were classified as Forest Type (forest 88%) and associated with the keywords traditional rural lifestyle, and sites to visit. Mixed Type (forest 50%, paddy field 20%, and other agricultural fields 10%) were associated with biodiversity and conservation activities, and Paddy Field Type (paddy field 60%) was significantly associated with Furusato (Home). Urban and Suburban Type sites (built-up land 50%) were concentrated in the Kanto Region and nominated mainly by local citizens for their nature activities. There was also the Other Agricultural Type, which made up 10% each of the nominations, and the Coastal Type, which was mostly nominated by ocean-related organizations and rarely nominated by the general public. Additionally, the concept of biodiversity seemed to be difficult for the public to understand. The results indicated that future studies should consider public perception of the variety of Satoyama landscapes and how it should be incorporated into future Satoyama management strategy. © 2010 International Consortium of Landscape and Ecological Engineering and Springer.

Kato H.,University of Tsukuba | Onda Y.,University of Tsukuba | Hisadome K.,Asia Air Survey Co. | Loffredo N.,University of Tsukuba | Kawamori A.,University of Tsukuba
Journal of Environmental Radioactivity | Year: 2015

In this study, we investigated the transfer of canopy-intercepted radiocesium to the forest floor following the Fukushima Dai-ichi Nuclear Power Plant accident. The 137Cs content of throughfall, stemflow, and litterfall were monitored in two coniferous stands (plantations of Japanese cedar) and a deciduous mixed broad-leaved forest stand (oak with red pine) from July 2011 to December 2012. The forest floor of cedar stands had received higher levels of additional 137Cs deposition compared with the mixed broad-leaved stand during the sampling period. The cumulative 137Cs deposition during the study period was 119kBq m-2 for the mature cedar stand, 105kBq m-2 for the young cedar stand, and 41.5kBq m-2 for the broad-leaved stand. The deposition of 137Cs to the forest floor occurred mainly in throughfall during the first rainy season, from July to September 2011 (<200d after the initial fallout); thereafter, the transfer of 137Cs from the canopy to forest floor occurred mainly through litterfall. A double exponential field-loss model, which was used to simulate the removal of 137Cs from canopies, was the best fit for the temporal changes in the canopy 137Cs inventory. © 2015 Elsevier Ltd.

Every year, earthquakes cause economic and human losses around the globe. In Japan, a great deal of attention has focused on improving the safety of structures and individuals in the last decade. The introduction here of several new related policies, together with continuous discussion of such policies, has raised the level of environmental security nationwide. Despite this significant effort, individual preparedness and awareness are still lacking, especially in rural areas, where technological advancements and policy applications often arrive late. In this paper, Kawaguchi in Niigata Prefecture, Japan was chosen as study area because of both the major damage experienced during the 2004 Chuetsu earthquake and the particularly dynamic socio-cultural activities of the community. Using interviews and questionnaires to collect information, this study aims to investigate the causes of local variations in community behaviour after the earthquake. Geographic location as well as everyday social relationships, social interactions and organization are considered the main causes of the differences in community organisation during the recovery process. This study highlights the necessity for more localised emergency education in order to promote longer-lasting awareness and preparation in rural areas. © Author(s) 2012.

Chiba T.,Asia Air Survey Co. | Hasi B.,Asia Air Survey Co.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2016

There are many methods to express topographical features of ground surface. In which, contour map has been the traditional method and along with development of digital data, surface model such as shaded relief map has been using for ground surface expression. Recently, data acquisition has been developed very much quick, demanding more advanced visualization method to express ground surface so as to effectively use the high quality data. In this study, the authors using the Red Relief Image Map (RRIM, Chiba et al., 2008) to express ground surface visualization for a variety of map scales. The authors used 30 m mesh data of SRTM to show the topographical features of western Mongolian and micro-topographical features of ground surface in tectonically active regions of Japan. The results show that, compared to traditional and other similar methods, the RRIM can express ground surface more precisely and 3-dimensionally, suggested its advanced usage for many fields of topographical visualization.

Oda K.,Asia Air Survey Co.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2014

Five-point algorithm is a powerful tool for relative orientation, because it requires no initial assumption of camera position. This algorithm determines an essential matrix from five point correspondences between two calibrated cameras, but results multiple solutions and some selecting process is required. This paper proposes Quasi-Five-Point Algorithm which is non-linear solver with seed solution of 8 point algorithm. The method tries to calculate the appropriate essential matrix without selecting process among multiple solutions. It is one of non-linear approach, but tries to find an appropriate seed before non-linear calculation. Using correspondences of 3 or more additional points, seed values of the solution is calculated. In this paper relationship between traditional parametric relative orientation and essential matrix is discussed, and after that quasi-five-point algorithm is introduced.

The computer main body includes a mesh size matching unit, a shading map generator, a red three-dimensional image generator, a raster image reader, a gradient reader, a floating-sinking degree reader, a first HSV converter, a mesh designator, a shading data reader, a second HSV converter, a hue reader, a first synthesis unit, a second synthesis unit, a third synthesis unit, an image output unit, a register, a color adjuster and the like, and causes the raster image RSGi having an elevation value to be viewed three-dimensionally.

A vector field, including its local three-dimensional attribute, is substantially visualized on a two-dimensional field of view in an intuitionally visible way. The vector field is mapped onto a three-dimensional coordinate space to produce corresponding coordinate point sequences, the degree of elevation in a local area of a plane in which the coordinate point sequences are connected is determined, the degree of depression in the local area is determined, the degree of elevation/depression in the local area is determined by weight-combining the degree of elevation and the degree of depression, the coordinate space is mapped onto a two-dimensional plane and gray-scale display corresponding to the degree of elevation/depression is conducted on the area of the two-dimensional plane corresponding to the local area.

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