Dear authors,

thank you very much for providing a revised version of your manuscript. After reading it carefully and taking the recommendations of the two reviewers into account, I would kindly ask you for some final round of minor revisions to the text addressing the comments listed below. After this last step, your paper should be ready for publication in NPG.

1. Abstract, ll.1-2 (and later: ll.36-37): You write that you consider five H-G variables but then list six properties (Q, W, D, U, S, n').
2. l.363: "Bryandywine" should probably read "Brandywine"
3. ll.458-461: I don't see how you can achieve the given factorization of f1(Q1+Q2) by considering f1=Q^m - I think this can only apply to f1(Q1*Q2). Please check.
4. The use of field data at different parts of the manuscript should be reorganized. Specifically, in ll.538-543 (Sec. 6) you make use of one of the data sets without explaining it before. In turn, the data are introduced in Sec. 7.3. It would be better to include a brief description of all data sets before their first use, eventually even as a separate section (e.g., before Sec. 6).
5. From the considerations in Sec. 7.1, can you provide a brief discussion on the relationship between SS-2 and fractality?
6. l.626: "As mentioned in Sect. 7.1" - I don't find this mentioned in the given subsection.
7. Results of field studies (from l.636 on): Could you provide upper/lower bounds on \alpha and \beta (i.e., when using D_T=1.7 or 1.8)? In general, for the empirical data, it would be good to give confidence bounds for all parameters. Can the deviations of some of the empirical results from theoretical predictions be (at least partly) explained by error propagation during the estimation?
8. Fig. 6 is referenced in the text before Figs. 3-5 (i.e., in l.674). Changing the order of figures is recommended.
9. ll.749-750: "probability distributions that are called generalized Horton laws" - this statement might benefit from some reformulation
10. ll.755-767: Some information on the Whitewater basin would be helpful, probably in relation with the above comment 4.
11. Fig. 1, caption: The sentence "Numbers beside points..." probably relates to Fig. 2, not Fig. 1.

As you realize, the requested changes are mostly of minor nature. The only somewhat more substantial change I recommend is bundling information on the empirical data at a somewhat more prominent position, leading to some minor restructuring of the text. I believe, however, that this is an important modification fostering the reading of your very interesting contribution.