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Set value for interpolation barrier for IDW/Spline/etc?

Question asked by mtrueheart on Jun 18, 2018
Latest reply on Jun 19, 2018 by cdspatial

I am attempting to "burn in" a river channel into a terrain model from depth soundings. The DEM is from a Lidar scan, so the river channel bottom is the water surface at the time of the flight. I have sonar depth-soundings of the river channel (point data) that I would like to use to correct the DEM. 

So what I have done is add many points along the river banks at zero depth, and tried kriging, IDW, spline, etc., to create an interpolation of the channel bottom from the depth soundings. The idea is to then subtract the resulting raster from the original DEM, to incorporate approximate bathymetry into the terrain.

However, the interpolation "overshoots" the zero value at the banks. I have tried using the "barrier" option on the IDW and spline functions, but this still leaves some spurious artifacts and I am not sure how to proceed. 

Is it possible to delineate the river banks with polylines, assign them a 0-value, and enforce them as boundaries to the interpolation? Or any other thoughts or ideas?

Thanks for any advice!