Creating a visual representation of Haiti's using QGIS
Digital Terrain Model of Haiti
01 / 01
1
Contour lines
Contour lines in a Digital Terrain Model (DTM) represent the elevation or height of the terrain at various points on the Earth's surface. They provide a visual representation of the topography of the land, showing how the elevation changes across a particular area.
Location: Péligre Dam and Artibonite Valley Google Earth Pro
DTM of the Peligre Dam, Haiti 2014
What contour lines show in a DTM:
- Elevation: Contour lines indicate the elevation of the terrain above a reference point, such as sea level or a specified vertical datum. Each contour line represents a specific elevation value.
- Terrain Features: Contour lines can reveal various terrain features, including hills, valleys, ridges, depressions, and slopes. By examining the spacing and arrangement of contour lines, you can interpret the shape and characteristics of the land.
- Slope and Steepness: The spacing between contour lines indicates the steepness of the terrain. Closely spaced contour lines indicate steep slopes, while widely spaced lines suggest gentle slopes. In some cases, contour lines may form concentric circles, indicating the presence of a hill or summit.
- Depressions and Pits: Contour lines that form closed loops within a larger contour indicate depressions or pits in the terrain, such as ponds, sinkholes, or craters. The innermost contour line within a closed loop represents the lowest point of the depression.
- Stream Channels: Contour lines can help identify the path and gradient of stream channels or rivers. Streams often follow the path of steepest descent, which is perpendicular to contour lines.
- Contour Interval: The contour interval is the vertical distance between adjacent contour lines. For example, if the contour interval is 10 meters, each contour line represents a change in elevation of 10 meters. Smaller contour intervals provide more detailed information about the terrain, while larger intervals offer a broader overview.
- Absolute and Relative Heights: By comparing contour lines, you can determine the relative heights of different locations on the map. For example, if one contour line is higher than another, you can infer that the area between them is a slope or hill.
They help cartographers, geologists, environmental scientists, and various other professionals understand the characteristics of the terrain and make informed decisions related to land use, construction, and resource management.
