Reply to comment by M. Bayani Cardenas and John L. Wilson on “Flow resistance and bed form geometry in a wide alluvial channel”

[1] The authors would like to thank Cardenas and Wilson [2006] for their valuable comments and interesting discussions. The main points raised by the commenters are summarized as follows. [2] 1. Cardenas and Wilson’s main interest lies in the estimation of the characteristic length (L00) of the separation zone behind the bed form. [3] 2. Equation (28a) of Yang et al. [2005] suggests that a may vary from 12 to 45, while Engel [1981] and Karahan and Peterson [1980] suggested that a has a value in the range of 4–6; thus it appears that equation (28a) overestimates the value of a by as much as 300% or more. The commenters concluded that the errors in a propagates into the analysis for the energy slope. [4] 3. The commenters were not clear on the values of a used for the calculation of Sc, and how Figure 4 of the Yang et al. was derived. The commenters assumed that the authors had used a value of a = 16 in the computation of energy slope S and found that the value of a was not constant. [5] The authors would like to stress that the objective of the paper is to develop a method to estimate the energy slope using easily obtainable data from the field or laboratory, such as the discharge, channel width, flow depth and sediment size. We will show that the different conclusions drawn by the commenters and the writers are attributable to the different research objectives. [6] First, the authors’ purpose is to evaluate the energy slope S which is expressed as follows (equation (6) of Yang et al.)