Hi,
I have never used ArcHydro tools before and I am hoping someone can help me with some basic floodplain delineation. I have a LiDAR DEM and a derived stream layer with Z-values. I am hoping to map the floodplain extent from these stream centerlines based on a 3m rise in water levels. Nothing more complicated than that. From what I have read so far, I need to "Flood Out WSE along streams in incremental steps"... But I am not sure what ArcHydro tools to use to do that.
Can anyone help?
Thanks,
Steve
Solved! Go to Solution.
Steve,
Depending on the quality of your DEM and streams, this could be an "easy" exercise. If your DEM and the flow direction match the placement and elevation of your streams, then you can directly use the HAND (Height Above Nearest Drainage) approach. You will need the following rasters (I suggest that you use .tif format for your rasters):
The steps are then (these are all core Spatial Analyst functions - you do not need Arc Hydro):
That’s it. In the output raster, where you have values, area is flooded and where it is nodata, it is “dry”. If you want to calculate depth of flooding for each cell, just use the MINUS function and use fe3m.tif and HAND.tif as inputs (in that order).
Hope this works for you.
Steve,
Depending on the quality of your DEM and streams, this could be an "easy" exercise. If your DEM and the flow direction match the placement and elevation of your streams, then you can directly use the HAND (Height Above Nearest Drainage) approach. You will need the following rasters (I suggest that you use .tif format for your rasters):
The steps are then (these are all core Spatial Analyst functions - you do not need Arc Hydro):
That’s it. In the output raster, where you have values, area is flooded and where it is nodata, it is “dry”. If you want to calculate depth of flooding for each cell, just use the MINUS function and use fe3m.tif and HAND.tif as inputs (in that order).
Hope this works for you.
That was super easy! Thanks so much.
Steve