Comments to Final Report Version 2.1

Contribution by Victor M. Ponce, Panelist

September 5, 2005

Suggested changes follow, in order of appearance.

Page 2, Executive Summary, paragraph 1: Replace "currently-used" with "currently used" (no hyphen). "Currently" is an adverb; hyphens are not used following adverbs.

Page 2, Executive Summary, paragraph 1: Replace "comercially-available" with "comerciallly available" (no hyphen). "Commercially" is an adverb.

Page 2, paragraph 3: Replace "The improved documentation will greatly help highlighting the current features" with "The improved documentation will greatly help to highlight the current features"

Page 4, paragraph 3: Replace "This final report version" with "This final report"

Page 5, paragraph 2: Replace "making it difficult for the Panel to easily assess" with "making it difficult for the Panel to assess readily"

Page 6, paragraph 1: Replace "This equation applicable for describing" with "This equation is applicable for describing"

Page 6, paragraph 1: Replace "canal-seepage" with "canal seepage"

Page 7, paragraph 3: Replace "under dynamic conditions where the model is not applicable;" with "under dynamic conditions where the model is not applicable," (Replace semicolon with comma; should make it clearer).

Page 10, section 2.5, Hydrologic Process Modules: Add the following paragraph at the beginning of this section:

The Panel is satisfied that the runoff curve number method is being used in a continuous-simulation mode by adjusting the value of maximum potential retention (S) based on the available soil-moisture storage. While the method's developers did not intend it to be used outside of event modeling (see http://mockus.sdsu.edu), it is correct to state that the method has been extended, by default and by practice, to the continuous simulation arena. The key is to do it carefully and transparently.

Page 13, paragraph 13: Replace "de-composition" with "decomposition"

Page 20, paragraph 1: Replace "well-crafted" with "well crafted" ("well" is an adverb)

Page 20, paragraph 2: Replace "physically-based, spatially-distributed" with "physically based, spatially distributed" (adverbs)

Page 20, paragraph 3: Replace "physically-based, spatially-distributed" with "physically based, spatially distributed" (adverbs)

Page 21, section 7, add the following paragraph at the end of the page (21):

The Panel is reassured that the District will make every effort to distinguish between the three types of errors which arise in mathematical modeling. First, numerical errors should be minimized; second, physical errors should be investigated, identified, and corrected; and third, data-quality errors should be acknowledged and, to the extent possible, resolved. As the District has adroitly recognized, disregarding this triad results in bad modeling practice.

Page 22, paragraph 1: This page appears to have an unfortunate error in the Draft Report Version 1.3. As is, the point is not made correctly; for additional clarification on this issue, see the Ponce and Jones discussion on the webboard.

Make the following correction (capitalization only to highlight changes):

Replace

"Another group of experts would argue that physical parameter ranges should be constrained to enforce the conceptual basis of the model. In this case, extreme, but still realistic, values of the optimal parameters would serve as an indication that conceptual problems might exist in the model"

with

"Another group of experts would argue that physical parameter ranges should NOT be constrained, in order to enforce the conceptual basis of the model. In this case, extreme AND OFTEN UNREALISTIC values of the optimal parameters would serve as an indication that conceptual problems might exist in the model"

Page 23, paragraph 1: Add the following sentence at the end of the first paragraph:

The Panel is reassured that the District will implement a three-stage parameter calibration to better simulate the nonlinearities inherent in the physical process.
050905