I have read over the referee reports and the authors' response. all referees supported the work and had mainly technical comments and helpful suggestions. I am happy that the author has taken suggestions and comments on board.

I would like to make one more editorial suggestion before publication, regarding step 7 of section 2.2 and the corresponding subfigure in Fig 1. (I had hoped a referee would make mention, but either all referees were OK with this, or I am missing something, but it is a very minor change i suggest.)

Ostensibly a given elevation contour is meant to be just that, i.e. an isoline of elevation. if i understand the algorithm correctly, if you begin with an elevation contour and advance to the next, barring any "exceptions" (all other cases in Fig 1) the next contour would be an isoline of elevation as well. So what can lead to a contour having variable elevation, as implied by Fig 1(a) and step 7? Does this only occur when the starting contour is at the margin, and a constant thickness (1m) and variable elevation necessarily leads to this contour not being an isoline of elevation? I think just a sentence could be included for verification.