원격탐사와 GIS 기법는 시공간 측면에서 매우 귀중한 정보를 제공할 수 있으며, 홍수와 같은 재해 발생시 홍수발생 지역에 대한 매핑, 모니터링 빚 재해지역 관리 등에 있어 매우 유용한 정보를 제공할 수 있다. 지난 2000년 메콩강 유역의 Tonle Sap호에서 발생한 홍수에 의해 많은 피해가 발생하였으며, 특히 7월과 10월 사이에 두 차례의 홍수 피크가 기록되었다. 본 연구에서는 홍수피해에 대한 정량적인 분석을 위해 ISODATA와 세크멘테이션 기법을 이용하여 Landsat ETM+와 RADARSAT 영상을 분석하였다. 그러나, 영상으로부터 분석된 범람면적이 구름과 복잡한 지표피복물 등으로 인해 실제 홍수피해 상황을 정확히 반영하지 못했다. 따라서, 이러한 문제점을 해결하고자 GIS 기능 중 비용-거리 (cost-distance) 기법을 이용하여 홍수범람 면적을 분석하였으며, 분석결과는 수치표고자료(DEM)와 중첩하여 홍수량을 계산하였다. 계산된 홍수량은 수리모형인 MIKE 11의 모델링 결과와 비교하였다. 계산결과 영상 내에 많은 구름이 존재하는 Landsat ETM+ 영상의 경우와 복잡한 지표피복이나 시스템 변수 등의 영향으로 홍수피해 지역을 정확히 분류하기 어려운 RADARSAT 영상에서도 좋은 결과를 얻을 수 있었다.
원격탐사와 GIS 기법는 시공간 측면에서 매우 귀중한 정보를 제공할 수 있으며, 홍수와 같은 재해 발생시 홍수발생 지역에 대한 매핑, 모니터링 빚 재해지역 관리 등에 있어 매우 유용한 정보를 제공할 수 있다. 지난 2000년 메콩강 유역의 Tonle Sap호에서 발생한 홍수에 의해 많은 피해가 발생하였으며, 특히 7월과 10월 사이에 두 차례의 홍수 피크가 기록되었다. 본 연구에서는 홍수피해에 대한 정량적인 분석을 위해 ISODATA와 세크멘테이션 기법을 이용하여 Landsat ETM+와 RADARSAT 영상을 분석하였다. 그러나, 영상으로부터 분석된 범람면적이 구름과 복잡한 지표피복물 등으로 인해 실제 홍수피해 상황을 정확히 반영하지 못했다. 따라서, 이러한 문제점을 해결하고자 GIS 기능 중 비용-거리 (cost-distance) 기법을 이용하여 홍수범람 면적을 분석하였으며, 분석결과는 수치표고자료(DEM)와 중첩하여 홍수량을 계산하였다. 계산된 홍수량은 수리모형인 MIKE 11의 모델링 결과와 비교하였다. 계산결과 영상 내에 많은 구름이 존재하는 Landsat ETM+ 영상의 경우와 복잡한 지표피복이나 시스템 변수 등의 영향으로 홍수피해 지역을 정확히 분류하기 어려운 RADARSAT 영상에서도 좋은 결과를 얻을 수 있었다.
The ability of remote sensing and GIS technique, which used to provide valuable informations in the time and space domain, has been known to be very useful in providing permanent records by mapping and monitoring flooded area. In 2000, floods were at the worst stage of devastation in Tonle Sap Lake,...
The ability of remote sensing and GIS technique, which used to provide valuable informations in the time and space domain, has been known to be very useful in providing permanent records by mapping and monitoring flooded area. In 2000, floods were at the worst stage of devastation in Tonle Sap Lake, Mekong River Basin, for the second time in records during July and October. In this study, Landsat ETM+ and RADARSAT imagery were used to obtain the basic information on computation of the inundation area and volume using ISODATA classifier and segmentation technique. However, the extracted inundatton area showed only a small fraction than the actually inundated area because of clouds in the imagery and complex ground conditions. To overcome these limitations, the cost-distance method of GIS was used to estimate the inundated area at the peak level by integrating the inundated area from satellite imagery in corporation with digital elevation model (DEM). The estimated inundation area was simply converted with the inundation volume using GIS. The inundation volume was compared with the volume based on hydraulic modeling with MIKE 11. which is the most poppular among the dynamic river modeling system. The method is suitable for estimating inundation volume even when Landsat ETM+ has many clouds in the imagery.
The ability of remote sensing and GIS technique, which used to provide valuable informations in the time and space domain, has been known to be very useful in providing permanent records by mapping and monitoring flooded area. In 2000, floods were at the worst stage of devastation in Tonle Sap Lake, Mekong River Basin, for the second time in records during July and October. In this study, Landsat ETM+ and RADARSAT imagery were used to obtain the basic information on computation of the inundation area and volume using ISODATA classifier and segmentation technique. However, the extracted inundatton area showed only a small fraction than the actually inundated area because of clouds in the imagery and complex ground conditions. To overcome these limitations, the cost-distance method of GIS was used to estimate the inundated area at the peak level by integrating the inundated area from satellite imagery in corporation with digital elevation model (DEM). The estimated inundation area was simply converted with the inundation volume using GIS. The inundation volume was compared with the volume based on hydraulic modeling with MIKE 11. which is the most poppular among the dynamic river modeling system. The method is suitable for estimating inundation volume even when Landsat ETM+ has many clouds in the imagery.
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제안 방법
The main steps of the overall methodology are presented in Figure 1. Also, the sensitivity analysis was carried out find the adequate spatial resolution to map the inundation area.
In this study, the inundation area and the inundation volume were estimated using Landsat ETM+ and RADARSAT imagery acquired in 2000 for Tonle Sap Lake, Mekong River Basin by integrating DEM and GIS. The results based on remote sensing data were compared with that of hydraulic modeling using MIKE 11.
The sensitivity analysis was conducted to investigate the applicability of the satellite imagery of the lower resolution such as MODIS and NOAA/AVHRR. The grid size of the satellite imagery and DEM for the sensitivity analysis was 250m, 500m, and 1,000m.
대상 데이터
Spatial data used in this study consist of satellite imagery and DEM. The satellite imagery employed is Landsat ETM+ and RADARSAT imagery (Table 1).
Spatial data used in this study consist of satellite imagery and DEM. The satellite imagery employed is Landsat ETM+ and RADARSAT imagery (Table 1). The SAR mounted onboard RADARSAT is a C-band system (5.
The study area is the floodplain of Tonle Sap Lake in the Mekong River basin, Cambodia. The most popular land use of this area is the paddy field and the shrub.
이론/모형
In the process of upgrading the DEM, MRC used SOGREAHs contour map and Philippine surveys results. The polyline was then converted to point using ArcView and the interpolation process was performed using IDW interpolation method with 100m×100m as the output grid (MRC, 2003).
To overcome these limitations, the cost-distance method of GIS was used to extract the accurate inundated area at the peak level in Kampong Loung (ESRI, 2000). The basic assumption to apply this method is that water has to flow out from the main river channel up to reach at least the areas recognized as inundated in the satellite imagery.
To overcome these limitations, the cost-distance method of GIS was used to extract the inundated area at the peak level in Kampoung Luong. The extracted inundation area was converted with the inundation volume by integrating DEM using GIS and it was compared with the result of hydraulic modeling using MIKE11 which is the most widely used dynamic river modeling system.
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