Do your images have the same resolution? If so, you should be able to use the Append Attributes filter to combine the elevation and drainage images into a single mesh with two fields. From there you can use one to warp and the other to color.
If the images have a different resolution, you should be able to use Resample with DataSet.
This solution is similar to what is discussed on this topic: https://discourse.paraview.org/t/difference-between-2-datasets/