Comments on: Google Earth Ground Overlays With GIF Transparency http://freegeographytools.com/2008/google-earth-ground-overlays-with-gif-transparency Exploring the world of free tools for GIS, GPS, Google Earth, neogeography, and more. Fri, 20 Apr 2012 04:10:35 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: Leszek Pawlowicz http://freegeographytools.com/2008/google-earth-ground-overlays-with-gif-transparency/comment-page-1#comment-1025 Leszek Pawlowicz Tue, 19 Feb 2008 20:10:45 +0000 http://freegeographytools.com/2008/google-earth-ground-overlays-with-gif-transparency#comment-1025 You're right, of course, and the post I reference describes how to create a basin flooding map using MicroDEM; you could use that basin flooding map instead of a flood fill as a Google Earth overlay. With this DEM, though, there's an additional problem doing a basin flood calculation. Because this DEM covers a limited geographic extent, if I start a basin flood calculation on one point, and if there's a land mass that blocks it completely, the area behind that blocking mass won't be flooded in the simulation, even though in real life there would be likely be other routes around that block to allow flooding to take place. The solution for that would be to use a DEM that covers a wider geographic extent. You’re right, of course, and the post I reference describes how to create a basin flooding map using MicroDEM; you could use that basin flooding map instead of a flood fill as a Google Earth overlay.

With this DEM, though, there’s an additional problem doing a basin flood calculation. Because this DEM covers a limited geographic extent, if I start a basin flood calculation on one point, and if there’s a land mass that blocks it completely, the area behind that blocking mass won’t be flooded in the simulation, even though in real life there would be likely be other routes around that block to allow flooding to take place. The solution for that would be to use a DEM that covers a wider geographic extent.

]]> By: SEWilco http://freegeographytools.com/2008/google-earth-ground-overlays-with-gif-transparency/comment-page-1#comment-1026 SEWilco Tue, 19 Feb 2008 19:28:00 +0000 http://freegeographytools.com/2008/google-earth-ground-overlays-with-gif-transparency#comment-1026 Basin flooding is only valid for a storm surge, where a range of hills may indeed block a temporary flood. If the water table is raised, a range of hills is only a temporary barrier and how quickly water goes through the hills depends upon the geology of those hills. Basin flooding is only valid for a storm surge, where a range of hills may indeed block a temporary flood. If the water table is raised, a range of hills is only a temporary barrier and how quickly water goes through the hills depends upon the geology of those hills.

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