(2000) assessed the effects of different large-scale DEMs on hydrologic runoff predictions and highlighted that different DEMs can lead to a difference of almost 10% in runoff predictions. However, whilst such derived versions are widely used, they still typically exhibit errors in the vertical much larger than those acceptable for many applications.įor instance, current global DEMs cannot resolve the detail of terrain features that control flooding ( Schumann et al., 2014).
Over the years, several processing algorithms and approaches for merging with other elevation datasets have been proposed to increase accuracy and remove vegetation biases ( Baugh et al., 2013 Robinson et al., 2014 O'Loughlin et al., 2016 Yamazaki et al., 2017 Yue et al., 2017). Schumann et al., 2008 Patel et al., 2016), the inherent errors in the SRTM-DEM are still notably unacceptable. Even though several studies have found actual errors to be considerably smaller than the requirements (see e.g. For instance, SRTM mission requirements defined absolute and relative elevation errors of 16 and 6 m, respectively ( Rabus et al., 2003). Freely available and global scale DEMs, such as that from the Shuttle Radar Topography Mission (SRTM) or from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) mission exhibit large vertical errors which are exacerbated over complex topography and they cannot resolve microtopographic variations in relatively flat terrain ( Gallien et al., 2011 Chu and Lindenschmidt, 2017).
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However, the availability of comprehensive DEMs for water resources studies is rather limited and limitations of current, free or open-access DEMs are well-known. Then go to the Filters menu (three dots together), in the Additional Filters > Filter type section select Hi-Res Terrain Corrected, then click on the Search button.įinally select the DEM that corresponds to your study area within the results panel, on the right hand side (or bottom) the DEM preview is shown, and you can also see the file size and download button.Digital elevation models (DEM) are recognized as a core spatial dataset required for many environmental applications. Then in the Dataset field select ALOS PALSAR – 2006 to 2011. The next step is to draw a polygon of the area of interest.
To download a free DEM you first need to register at (if you already have an EarthData account, you can log in directly).
#DIGITAL TERRAIN MODEL DOWNLOAD FREE HOW TO#
In this post we are going to see how to download a 12.5 meter resolution DEM from ALOS PALSAR, which from 2006 to 2011, PALSAR’s L-band Synthetic Aperture Radar (SAR) allowed detailed, all-weather, day and night observation and repeat-pass interferometry ( more information can be found here). A fairly common problem is usually the access to spatial information, in this case Digital Elevation Models (DEM) are not always available to everyone, either by cost, availability, or lack of knowledge to obtain them.
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