TopographyGlaciation affected Estonian landscapes in different ways depending both on the behavior of the glacier and on bedrock control. In the region around the Endla Mire Complex bedrock control and glacial deposits combine to produce a pattern of wetlands bounded by higher drier land. This pattern is reflected in the hydrology, vegetation, and landuse.The following links provide a visual overview of the landscape: (Twinning, Estonia; Kite Photography, Endla); Seasons, Endla).
Scope of the ProjectThis project focuses on the impact of topography on hydrology, vegetation, and landuse as seen in a Landsat ETM image acquired on 10 July 1999. Seven bands are used in the analysis, including visible and infrared bands, and a thermal band.MethodologyTo show topography a digital elevation model (DEM) would be desirable. However, a suitable DEM was not available. Instead a topographic map was used to produce an image showing land above and below the 80-meter (260-foot) contour. This is a reasonable approach since the highest and lowest elevations were about 70 meters and 95 meters, a relief of only 25 meters (80 feet).Four additional overlays were developed to show landuse: roads; railway; and the nature reserve boundary. These were all georeferenced to the same coordinate system as the Landsat image using the same techniques as described in GIS Methods . |
Almost Natural Composite Landsat ImageMany composite images used for scientific purposes do not look natural because the images used do not maintain natural color balance. This image is not a natural color image, but it is designed so that greens are green. In fact, an infrared band is responsible for the emphasis on vegetation.
Composite Landsat ImageComposite Landsat images can be designed to display specific features. Bands 3, 4, and 5 displayed as blue, green, and red contain almost all of the imformation in a dataset. Band 3 is the red chlorophyll absorption band, useful to show plants versus bare soil. Band 4 is the reflective infra-red band, discriminating between types of vegetation and between land and water. Band 5 is sensituve to the turgidity of plant tissues, indicating plant vigor. This image has overlays showing the relationship between vegetation and other features.
Cluster AnalysisAll bands of a Landsat dataset can be used to derive a classification of features in a scene. This image uses the composite shown above to derive a six-fold classification of features using the isocluster approach. This image has overlays showing the relationship between vegetation and other features.
Seasonal DifferencesSeasonal variations in a landscape are revealed in satellite images. Sometimes patterns of light reflected differently from snow and bare soil can be useful in interpretation. This scene is from early March when snow and ice remain in some parts of the scene and bare soil in others.
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