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ransara

Correcting a DEM along a River or Channel

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Dear Friends,

 

I need help to correct a DEM along the streams. When I make a DEM with Contours, generally steps are creating along the streams. This is not correct for flood plain simulations. I tried with both Triangulation and raster options.  Unfortunately I can't paste a photo here. I think my point is clear.

 

Can someone advice me how to correct this ? My study area is big and so many streams.

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You can try TOPO TO RASTER Tool in the ArcToolbox, this tool enabling us to include some dataset as the interpolation control live river layer, height point layer, break lines layer, etc

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you can "burn in" your stream along the dem, 

I usually using HEC-GeoHMS extension to do that :D

for building dem dont forget using hidrologically corrected dem tools to make a dem valid for flood plain simulation

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other advice could be use your existing DEM to create height points and/or contours, then use the Topo to Raster tool to re-create a hydrologically correct DEM including your water network. I'm not 100% certain how different the resultant surface would be from your original DEM, though you can be sure it'll work for creating stream networks, if exact height measures aren't vital. The Topo to Raster tool also allows for other hydrologically significant features such as water bodies and known sinks (credit :http://gis.stackexchange.com/questions/18595/burning-stream-network-into-dem-layer-using-arcgis-desktop)

 

regards 

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Creating DEMs from contours commonly produces steps around the contour locations unless the contours are very closely spaced.  Try looking at the histogram of your DEM with small bins to see how bad the problem is.

 

One partial solution I have used along streams is as follows:

 

1. Extract the points along the individual stream segments then interpolate elevations between them.  For example, let's say your elevation points are 50 m apart (distance not elevation), then create a set of points 10 m apart.  I believe the ET Geowizards let's you create these "station points".  Hawth's Tools used to let you do this also for older versions of ARCMAP  - not sure about its successor.

 

2. Since you know the distance of the station points along the stream line, you can interpolate elevations for them from your known elevations along the stream line.  Do this outside ARCMAP using data from the dbf file.

 

3.  Convert your contours to points & add your station point elevations.

 

4. Recreate the DEM raster from the points.

 

This won't fix the step issue elsewhere but it will create stream lines that flow downhill, 

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Hi oz1....that is a good option. I am trying all the options and going to find the best method. Once i finished the experiments i will write here for benefit of others. 

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