Digital Elevation Model, DEM:

The digital elevation model since its creation in the 50's has been a means for the knowledge and representation of the terrain and to achieve analysis of the elements present in it. At present, the models constitute a means to achieve the representation of the relief since from it, it is possible to know the conformation or morphology of the terrain (MOT) as well as the elements of anthropic origin and the vegetation present in it (MDS) [ 1]

The methods currently used to generate Digital Elevation Models are:

• From the photogrammetric cross-correlation method:: The image cross-correlation technique is based on the comparison of digital images from stereoscopic pairs of digitized aerial photographs.


• LiDAR technology (acronym for Light Detection and Ranging”, that is, “Detection and Measurement through Light”): LiDAR is the combination of technologies designed to obtain three-dimensional coordinates (X, Y, Z ), from ground points using laser rangefinders.

In digital elevation models, there are two essential qualities: accuracy and horizontal resolution or degree of digital detail of representation in digital format, which vary depending on the method used to generate them.

For WaterProof, the DEM provided by HydroSHEDS has appropriate features, given the 1 km resolution it provides, which are obtained from the Radar Shuttle Topography Mission (SRTM) at a resolution of 3 arc seconds. The interesting thing is that HydroSHEDS provides a DEM -STRM retrofitted with the Digital Chart of the World (also known as VMAP0) river network; the Global Lakes and Wetlands Database (GLWD); and several other global and regional digital river maps, ensuring globally consistent topological connectivity of the river network.

It is worth mentioning that WaterProof completed the information with data from the TAMDEM-X90m database since the SRTM mission does not cover the entire North Pole.

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