Comment on "Global search algorithm for nondispersive flowpath extraction" by Kyungrock Paik

Paik [2008] presents a new algorithm for the extractionof surface flow paths from gridded elevation data,arguing that ‘‘significant improvement over the limitationof D8 and D8-LTD [methods] can be achieved using a new and simple idea without introducing any model parameter’’ [Paik, 2008, paragraph 9]. However, all Paik’s [2008] arguments against Orlandini et al.’s [2003] D8-LTD method can be shown to be unsubstantial merely on the basis of geometrical considerations. The purpose of the present comment is to point out that (1) an analytical background to support the decision to set the dampening factor equal to 1 in the D8-LTD method does exist and (2) results obtained from incorrect implementations of the D8-LTDmethod are used in the investigation of Paik [2008]. Further considerations on Paik’s [2008] analysis of the D8-LTD method are also provided.