• Title/Summary/Keyword: Topographic

Search Result 1,530, Processing Time 0.024 seconds

PROBABILISTIC LANDSLIDE SUSCEPTIBILITY AND FACTOR EFFECT ANALYSIS

  • LEE SARO;AB TALIB JASMI
    • Proceedings of the KSRS Conference
    • /
    • 2004.10a
    • /
    • pp.306-309
    • /
    • 2004
  • The susceptibility of landslides and the effect of landslide-related factors at Penang in Malaysia using the Geographic Information System (GIS) and remote sensing data have been evaluated. Landslide locations were identified in the study area from interpretation of aerial photographs and from field surveys. Topographical and geological data and satellite images were collected, processed, and constructed into a spatial database using GIS and image processing. The factors chosen that influence landslide occurrence were: topographic slope, topographic aspect, topographic curvature and distance from drainage, all from the topographic database; lithology and distance from lineament, taken from the geologic database; land use from Landsat TM (Thermatic Mapper) satellite images; and the vegetation index value from SPOT HRV (High Resolution Visible) satellite images. Landslide hazardous areas were analysed and mapped using the landslide-occurrence factors employing the probability-frequency ratio method. To assess the effect of these factors, each factor was excluded from the analysis, and its effect verified using the landslide location data. As a result, land 'cover had relatively positive effects, and lithology had relatively negative effects on the landslide susceptibility maps in the study area. In addition, the landslide susceptibility maps using the all factors showed the relatively good results.

  • PDF

INFLUNCE OF THE TOPOGRAPHIC INTERPOLATION METHODS ON HIGH-RESOLUTION WIND FIELD SIMULATION WITH SRTM ELEVATION DATA OVER THE COASTAL AREA

  • Kim, Yoo-Keun;Lo, So-Young;Jeong, Ju-Hee
    • Proceedings of the KSRS Conference
    • /
    • 2008.10a
    • /
    • pp.297-300
    • /
    • 2008
  • High-resolution mesoscale meteorological modeling requires more accurate and higher resolution digital elevation model (DEM) data. Shuttle Radar Topographic Mission (SRTM) has created 90 m DEM for entire globe and that is freely available for meteorological modeling and environmental applications. In this research, the effects of the topographic interpolation methods on high-resolution wind field simulation in the coastal regions were quantitatively analyzed using Weather Research and Forecasting (WRF) model with SRTM data. Sensitivity experiments with three different interpolation schemes (four-point bilinear, sixteen-point overlapping parabolic and nearest neighbor interpolation methods) were preformed using SRTM. In WRF modeling with sixteen-point overlapping parabolic interpolation, the coastal line and some small islands show more clearly than other cases. The maximum height of inland is around 140 meters higher, while the minimum of sea height is about 80 meter lower. As it concerns the results of each scheme it seems that the sixteen-point overlapping parabolic scheme indicates the well agreement with observed surface wind data. Consequently, topographic changes due to interpolation methods can lead to the significant influence on mesoscale wind field simulation of WRF modeling.

  • PDF

A Study on the Data Model of Topographic-Cadastral Map (지형.지번도의 데이터모델에 관한 연구)

  • 최윤수;고준환;서용운;이석용
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
    • /
    • v.19 no.1
    • /
    • pp.85-93
    • /
    • 2001
  • Digital mapping project of topographic map was conducted according to the master plan for the development of the National Geographic Information System, to manage national geo-spatial information efficiently in rapidly changing information technology society. It needed to correct and supplement digital map because of time pressure, sudden urbanization and users'need. In this study, after the framework data of thematic map was given a definition based on data model of National Base Map, data model of topographic-cadastral map was presented. Also data format and meta data suited to presented data model of topographic-cadastral map were presented so that they could be used in various fields.

  • PDF

Variation in Vegetation Area caused by Topographical Change at Jinudo in the Nakdong Estuary (낙동강 하구역 진우도내 지형변동에 따른 식생면적의 변화)

  • Ryu, Sung-Hoon;Lee, In-Cheol;Park, So-Young
    • Journal of Ocean Engineering and Technology
    • /
    • v.23 no.4
    • /
    • pp.19-24
    • /
    • 2009
  • In order to analysis the variation in vegetation area caused by topographical change at Jinudo in the Nakdong estuary, we used aerial photographs of Jinudo from 1998 to 2006. To extract an accuracy shoreline from these aerial photographs, a tide calibration was performed. We also estimated the annual variation in topographic area and vegetation area, and then analyzed the relationship between them by a correlation analysis. The following results were obtained: 1) The calibrated shoreline distance of Jinudo from 1998 to 2006 was estimated to have a range of (-)1,927 cm to (+)4,671 cm. 2) Annual changes in the topographic area and vegetation area in Jinudo have been increasing gradually from 1998, and the correlation coefficient between topographic area and vegetation area is 0.97. 3) The estimated topographic areas were with following order: southern (III), eastern (IV), northern (II) and western (I), while for the vegetation area, the order was southern (III), northern (II), eastern (IV) and western (I). 4) The vegetation area of the southern region (III) of Jinudo had the largest size among the regions, and was calculated to be $4.3{\sim}5.4$ times larger than the eastern region (IV).

Calculation of Watershed Topographic Index with Geographic Information System (지리정보시스템을 이용한 유역에서의 지형지수 산정)

  • 김상현;한건연
    • Water for future
    • /
    • v.29 no.4
    • /
    • pp.199-208
    • /
    • 1996
  • The multiple flow direction algorithm to calculate the spatial variation of the saturation tendency, i.e. topographic index, is integrated into the Geogrphic Information System, GRASS. A procedure is suggested to consider the effect of a tile system on calculating the topographic index. A small agricultural subwatershed (3.4$\textrm{km}^2$) is used for this study. The impact of a tile system on the groundwater table can be effectively considered by the Laplace's equation to the DEM. The analysis shows that a tile system has a high degree of saturation compared to the case without tile drainage, and the predicted riparian area is well fitted to the actual watershed condition. A procedure is suggested to consider the effect of tile system on calculating the topographic index.

  • PDF

Accuracy Evaluation of ASTER DEM, SRTM DEM using Digital Topographic Map (1:5000 수치지형도를 이용한 ASTER DEM과 SRTM DEM의 구축정확도 평가)

  • Kang, Kyung-Ho;Kim, Chang-Jae;Sohn, Hong-Gyoo;Lee, Won-Hee
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
    • /
    • v.28 no.1
    • /
    • pp.169-178
    • /
    • 2010
  • The main purpose of this study is to evaluate the feasibility and the accuracy of ASTER DEM and SRTM DEM covering 99% of the earth surface using large-scale Digital Topographic Map in mountainous area(Sokcho), mixed area(Jinan, mountainous area and even land area) and even land area(Anyang). We made DEM using contour lines of 1:5,000 Digital Topographic Map of study area and also acquired ASTER DEM and SRTM DEM of their corresponding area. In order to verify accuracy of DEM, this study compared ASTER DEM and SRTM DEM data using 15m resolution DEM generated from contour lines of Digital Topographic Map as basis for each study area. To evaluate the accuracy of ASTER and SRTM DEM data, statistical such as RMSE and correlation were calculated and histogram and scatter plot were drawn. The analysis result shows that, both ASTER DEM and SRTM DEM have high accuracy but in aspects of future availability, ASTER DEM covering larger areas bas relatively more potential than SRTM data.

Accuracy Analysis of Ortho Imagery with Different Topographic Characteristic (지역적 특성에 따른 정사영상의 정확도 분석)

  • Jo, Hyun-Wook;Park, Joon-Kyu
    • Journal of the Korean Association of Geographic Information Studies
    • /
    • v.11 no.1
    • /
    • pp.80-89
    • /
    • 2008
  • Mapping applications using satellite imagery have been possible to quantitative analysis since SPOT satellite with stereo image was launched. Especially, high resolution satellite imagery was efficiently used in the field of digital mapping for the areas which are difficult to produce large-scale maps by aerial photogrammetry or carry out ground control point surveying due to unaccessibility. This study extracted the geospatial information out of consideration for topographic characteristic from ortho imagery of the National Geospatial-intelligence Agency(NGA) in the United States of America and analyzed the accuracy of plane coordinate for ortho imagery. For this purpose, the accuracy according to topographic character by comparison between both extraction data from ortho imagery and the digital topographic maps of 1:5000 scale which were produced by Korea National Geographic Information Institute(NGI) was evaluated. It is expected that the results of this study will be fully used as basic information for ground control point acquisition or digital mapping in unaccessible area.

  • PDF

An Analysis of DEM and Gravity Effect for Precision Geoid Determination in Korea (우리나라 정밀지오이드 구축을 위한 지형자료 및 중력자료 영향 분석)

  • Lee, Bo-Mi;Lee, Ji-Sun;Kwon, Jay-Hyoun;Lee, Yong-Wook
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
    • /
    • v.26 no.5
    • /
    • pp.519-527
    • /
    • 2008
  • The basic elements in precise geoid determination are the gravity and topographic data with reliable quality and distribution. In this study, the effect of the gravity and topographic data on the precision of the geoid are analyzed through simulations in which the quality and distribution of the data are artificially controlled. It was found that the distribution of the topographic data has more effect on the precision of geoid than the quality of the it. This leads to the conclusion that the SRTM (Shuttle Radar Topography Mission) DTM (Digital Terrain Model) with resolution of 90m is qualified as a topographic data in geoid determination. In the experiments with gravity data, on the other hand, the aliasing effect caused by the low data density caused large errors in geoid. It was found that the more gravity data especially in north-eastern mountainous area is needed for precise geoid determination in Korea.

Long-Term Investigation of Regional Topographic Effects on Soil Chemical Properties and Heavy Metal Concentrations in Paddy Fields

  • Ahn, Byung-Koo;Kang, Seong-Soo;Shin, Jae-Yeon;Lee, Jin-Ho
    • Korean Journal of Soil Science and Fertilizer
    • /
    • v.45 no.5
    • /
    • pp.738-743
    • /
    • 2012
  • Topographic conditions of agricultural fields work as a important factor to identify different soil properties. This study was conducted to investigate the selected soil chemical properties and the concentrations of heavy metals, Cd, Cr, Pb, Cu, Ni, and Zn, in the paddy fields of different topographic areas at four year intervals from 1999 to 2011. Three-hundred soil sampling sites in the paddy fields were selected from the different topographic areas that were local valley and fans, fluvio-marine deposits, alluvial plains, and diluvial terraces. The mean values of soil pH ranged 5.7~5.8 that were within optimal range for rice cultivation. The mean values of other properties such as soil organic matter (SOM) content, the concentrations of exchangeable cations, $K^+$, $Ca^{2+}$, and $Mg^{2+}$, and available silicate concentration were lower or close to the optimal values, but the mean concentrations of available phosphorus were exceeded the range of optimal value, $80{\sim}120mg\;kg^{-1}$, in many paddy fields. In particular, The concentrations of available phosphorus in the paddy fields of local valley and fans, alluvial plains, and fluvio-marine plains were mostly declined. However, in diluvial terrace areas, the phosphorus concentrations unexpectedly increased; furthermore, they were significantly higher than those in other topographic areas. The mean concentrations of 0.1 M HCl-extractable heavy metals, Cd, Cr, Pb, Cu, Ni, and Zn, in the paddy fields were slightly and gradually declined during the study years, but the Pb concentrations were not statistically changed. In addition, the concentrations of heavy metals were widely ranged depending on the different sampling sites. Nevertheless, the concentrations of heavy metals were significantly lower than the levels of Soil Contamination Warning Standard (SCWS) for agricultural lands (1-region) presented in Soil Environment Conservation Law (SECL).

Rainfall Adjustment on Duration and Topographic Elevation (지속시간 및 표고에 따른 강우량 보정에 관한 연구)

  • Um, Myoung-Jin;Cho, Won-Cheol;Rim, Hae-Wook
    • Journal of Korea Water Resources Association
    • /
    • v.40 no.7
    • /
    • pp.511-521
    • /
    • 2007
  • The objective of this study is to develop a method of rainfall adjustment on duration and topographic elevation for rainfall data in Jejudo. The method of rainfall adjustment is based on the polynomial regression analysis for the hourly rainfall data and the distribution of observatories of korea meteorological administration. As the results of modeling have shown, duration and rainfall are more correlated than topographic elevation and rainfall, and the model which considers only an elevation exaggerates the amount of rainfall adjustment. Hence the model of duration-elevation-rainfall is more competitive to the natural rainfall event than the model of topographic elevation-rainfall. However this model require to supplement a small number of rainfall observatories and short observed period.