Appendix A In general, this section is well structured and well written, but contains certain grammatical errors that need to be corrected before the document is presented in final form (see below). Page 57, paragraph 1, 3rd sentence:   Avoid starting a sentence with "And" Page 57, paragraph 2:   Replace "Numerous articles" with "Several articles" Page 57, paragraph 2:   Replace "should also be consulted prior to the application" with "provide the bakground documentation for the application" Page 57, paragraph 2:   Replace "numerous operational alternatives" with "many operational alternatives" Page 57, paragraph 2:   Replace "any other model" with "other models" (Overstated). Page 57, paragraph 3:   Reword "One should be very careful..." Perhaps "Users should be very careful..." will do. Page 57, paragraph 4:   Replace "does not say anything" with "says little" (Overstated) Page 58, paragraph 1, number 4:   Replace "well-  posed" with "well-posed" Page 58, paragraph 1, number 8:   How was the value 10% maximum error in mass conservation determined? Page 58, paragraph 2:   Reword "One should consider..." Page 58, paragraph 3:   Replace "hydlorogic" with "hydrologic" (Typo) page 59, section A.2, number 1:   Replace "a variety of hydrologic models to understand the underlying" with "a variety of hydrologic models to describe the underlying" Page 59, section A.2, number 2:   Delete "in the model structure" (unnecessary) Page 59, section A.2, number 2:   Replace "without having to abandon the entire model" with "without becoming obsolecent" Page 60, number 6:   Replace "Even if a certain amount of this is inevitable" with "Even is a certain amount of this practice is inevitable" Page 60, number 6:   Replace "Anyone" with "Other parties" or "Third parties" Page 60, number 6:   Replace "should be allowed and even encouraged to do so" with "can do so" Page 60, number 8:   Replace "Non personal" with "Non-personal" Page 60, number 8:   Replace "the use of scientific method falling to the original authors" with "the credit for the development of a scientific method falling to the original authors" Page 60, number 8:   In this paragraph, you may want to use the word "open source." This is a commonly used term to denote the fact that the source code is open to anybody willing to participate.