Fill Burn filling complete DEM

[Jean-François Bourdon]

Is the complete DEM filling of the Fill Burn tool the expected behavior? When I used it the first time, I was expecting to only see the cells under the provided vector lines to be burned and filled, not also all other depressions. My intention was to use Fill Burn to burn known culverts and then send the output to Breach Depressions Least Cost to finish the job. Unfortunately, it's not (directly) possible if the DEM is filled. My workaround is to extract the output cells under the vector lines and burn them on the original DEM using a mask.

[Brian Kielstra]

Yes, it looks like this is the expected behavior. There is a priority flood operation in the FillBurn code. 

From Lindsay (2006):

"Saunders (1999) described an algorithm, referred to as FillBurn, which used this
combination of line thinning after rasterization, a constant elevation offset, and depression filling."

and then from Saunders (1999) : 

"Three of the four hydrography integration algorithms can be referred to as "stream burning" algorithms. The fourth, Agree.aml, is more accurately described as a surface reconditioning algorithm. The three stream burning programs have a common structure: (1) convert the pre-processed hydrography layer to a grid representation of the stream network, (2) perform a thinning process on the grid to reduce the flow paths to a single cell width, (3) implement a method of burning the stream grid cells into the landscape, (4) execute a fill command to ensure that no elevation depressions occur, and (5) execute the flowdirection and flowaccumulation commands. What follows is a brief description of the hydrography integration technique employed in each of the AML programs:

Fillburn.aml - This stream burning algorithm assigns all stream grid cells with the elevation values from the original DEM while assigning all off-stream cells with the DEM values plus an offset value of 1000 meters. After the fill command is executed, the stream-burned grid is algebraically subtracted from the filled grid and the largest value in the resulting difference grid is recorded. Once that value is retrieved, the 1000 meter offset is subtracted from the off-stream values, while the stream grid cells are reduced by the maximum value from the difference grid, incremented by one. This process ensures that the stream burning offset value is only one unit deeper than the amount of the maximum fill height."

[Jean-François Bourdon]

Thanks, I should have took the time to read the references. So the tool is really meant to produce a complete hydro-enforced DEM and not only burning and then filling streams. I'll suggest a precision for tool description then.

[Anthony Francioni]

We are working on re-implementing the TopologicalBreachBurn tool in WBT from that Lindsay (2016) paper that Brian alluded to. Hopefully it will be available soon. It will be a more precise tool for burning in streams than other options. In fact, I believe that algorithm is likely the most precise such stream burning method, in light of the fact that it tries to minimize topological error in the rasterization of the stream vector during the burning operation.

Cheers,

John

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[Jean-François Bourdon]

A new TopologicalBreachBurn tool is excellent news as I had on my TODO list working on a tool to breach streams/culverts from vectors that would have used part of BreachDepressions tools. I will be more than willing to beta-test this tool if necessary.