Digital Elevation Models (DEMs) play a critical role in hydrological analysis, enabling the identification of streams, mapping of watershed boundaries, and much more. However, acquiring a suitable DEM for your study area can often be a complex and time-consuming process. This typically involves searching through numerous federal, state, and local repositories, downloading multiple 1km x 1km tiles, assembling them, reprojecting the data, and clipping it to the area of interest. For many analysts, this process is both tedious and resource-intensive.
To simplify this workflow, Arc Hydro, the free add-in for ArcGIS Pro now offers a powerful new tool called “Download DEM” in build 3.2.52 or higher. This tool automates many of the most time-consuming steps in DEM preparation, providing a streamlined approach to acquiring and preparing elevation data. With this tool, users can:
This tool eliminates the need for manual data wrangling and allows users to focus on analysis and decision-making. By automating the most labor-intensive tasks, the tool not only saves time but also ensures consistency and accuracy in DEM preparation. The Download DEM tool can be found in the Flood Simulation toolset within the Arc Hydro Tools Pro toolbox:
Figure 1 Tool Location
Figure 2 Tool User Interface
To learn more about Arc Hydro and download the toolset visit the download page here.
The Elevation Source parameter allows users to specify where their DEM data should be sourced. Currently, the tool supports USGS 3DEP elevation data, with plans to expand its options in future updates. If you have suggestions for additional publicly available elevation sources, we encourage you to comment on this blog post. The Arc Hydro team values user feedback and will consider your recommendations in the next development cycle.
The U.S. Geological Survey’s 3D Elevation Program (3DEP) provides high-quality, 1 meter elevation data across most the United States. 3DEP data offers detailed terrain information suitable for a wide range of applications, including hydrology, infrastructure planning, and natural resource management. The program’s nationwide coverage ensures that users can access consistent elevation data for virtually any location within the U.S.
What makes 3DEP particularly advantageous for terrain analysis is its combination of accuracy, coverage, and accessibility. The data is derived from advanced lidar and interferometric synthetic aperture radar (IfSAR) technologies, ensuring precision and reliability.
Figure 3 3DEP Images from USGS website
Here is an example of how the “Download DEM” tool can simplify terrain analysis. Imagine you have identified a watershed for which you would like to create a stream network. To get started, bring a polygon feature class with a polygon defining your area of interest into an ArcGIS Pro project, ensuring that it is projected in the desired coordinate system for the DEM you want to download.
Figure 4 Study area defined by a watershed
Figure 5 Study area projection
Next, open the “Download DEM” tool and add your polygon to the Input Study Area Feature Class parameter.
Figure 6 Tool interface with parameters populated
Leave all other parameters as default and run the tool. The runtime of the tool will vary depending on the size of your input study area. Once the process is complete, a DEM will be added to your map. This DEM will already be clipped to the extent of your study area and projected to the desired coordinate system.
Figure 7 Download DEM output results
For better visualization, consider applying a shaded relief raster function to the DEM. This will provide a clearer understanding of the high-resolution elevation data you have downloaded.
Figure 8 Shaded relief applied to the DEM
With the DEM prepared, you can proceed with further analyses, such as deriving a stream network.
Figure 9 Streams derived from the DEM
The new Arc Hydro “Download DEM” tool offers a quick and efficient way to obtain high-resolution elevation data that is clipped and projected to a user-defined study area. By automating these time-consuming steps, the tool allows analysts to spend less time on data preparation and more time on meaningful analysis.
Next time you are asked, “Where did you get that DEM from?” you can confidently respond, “I used Arc Hydro.”
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