DamDestoyer:
An ArcGIS Toolbox for Extracting Hydrology from LiDAR DEM's
To request a download of the DamDestroyer toolbox (.tbx), please email nbeningson@gmail.com
LiDAR digital elevation models (DEM's) offer an unprecedented view of terrain at high resolutions across large scales. A plane with a laser array coats the landscape with millions of laser shots, with each one returning a point of elevation. These data can be synthesized into models of the landscape with different uses– for a geologist, typically a "bare earth" model simulating what the world would look like as bare ground, with no vegetation. With each pixel representing a 1x1 meter (or less!) square on the ground, features instantly become recognizable: every little hill, river, drainage ditch, and roadway stands out in ways not seen in traditional satellite imagery. By using LiDAR digital elevation models to track where water is flowing, scientists can study more detailed questions examining river erosion, flood events, or agricultural runoff.
Traditional DEM's compared to a finer resolution LiDAR DEM
Modeling hydrology using LiDAR runs into issues where roadways cross rivers. LiDAR only maps the surface, so that elevated bridges stick out like artificial dams on the landscape. The tools calculating where rivers flow cannot tell where culverts actually are. This can dramatically reroute calculated stream pathways sideways, or even uphill, resulting in inaccurate stream networks. Previous hydrology products are no use, as they are derived from data with much coarser resolutions.
The modeled river flow, shown in light blue, is cut off by the roadway running horizontally across the image. Areas where flow is significantly affected are circled in red
DamDestroyer intelligently removes these artificial dams from LiDAR DEM's, enabling flow modeling on the scales from single agricultural fields up to entire watersheds. DamDestroyer is an ArcGIS toolbox using spatial analyst designed for the average user. In four steps, the tools identify areas artificially dammed by roadways, find paths to breach the dams, burn these paths into the DEM, and calculates a new flow network. For more information about how DamDestroyer works, please consult the Examples or User Manual.