WSPC126 - Laserfiche WebLink

Home Browse Search

. ~.. -f'": ~ '.... ,.... -) . . :':'~l'~--'-'; ~~l(J '.\..':,/ ;:',/ 00031.9 e e , 'ji I DRAFT WORKING LIST OF ASSUMPTIONS AND GROUND RULES (MARCH 31, 1999) 1. study Period. The Preliminary BO uses the 1972-91 water years for the study period. Is this acceptable or do we want to use another period of record? _/' _, (II. . . /~ I ~ c-c--,_c.....e P"'~ e... Most of the analysis in the Preliminary BO is done on a wet year (1986)~ dzy year(1989) and an a"-erage year (1982); the emire 1975-91 stady period was not generally used in the BO' s analysis. Is this what we want to do? Or~ do we want to use the entire study period? 2. BaseIiDe Hydrolo:,y. The Preliminary BO uses the C1 Sce:uario. The C 1 Scenario uses historic gage data with the excepti~t irrigation demands are calculated from a""erage irrigation efficieacies for the study period. 1975-19911' .lne Cl nm also includes backcasting of 1996 water year demands throughout the entire study period.. The a'\o'CI'3ge annual depletions for these existing d.C:mands are used for every )'ear. Depletions ftom demands that were in place for a potion oftbe 1975-91 period were included in the C 1 IUD. for the entire study period. Depletions from new demandc: such as Ruedi Round 1 and 2 are also included. This liSt of all the projects that were included in the backcasting at their 1996 demand levels is on page 3 of Appendix D. . , ~The Service has indicated (memo from Hemy Maddux to Randy Seaholm. February 2. 1999) that the baseline ~~olo~ sh~ be the CI run \'lith ~e existing flow re~ ~RAP ~ inClud, ed. The Senice also indicated m: this Memo that "'Category 1" Items should not be included m the baseline because they may be part of the solution. (Should this be Category 1 instead of Category 2?). ),..o.,Q \l.~'" vI \ ~-,=---- Do'We'waDt: to uSe the Cl Scenario,~ our base case for puzposes of estimating the quantitative effects of the various aItematives for ~-ieldiug water for the fish? Or, do we want to: (1) modif)' C 1 to make it more to our Iildn& or (2) use sorneti1mg entirely different? Ifwe are going to accept C 1 for use as our baseline hydrology, it will be important that everyone is satisfied with the depletion levels listed in R~ised Appendix A for existing projects with backcasted demands. 3. ' Model aDd Time Step. StareMod will probably be the model of choice for that modeling which can be accomplished with a momhIy time step. It is suspea.ed, however, that a daily time step model will be necessary durini certain. periods in order to meet the overall objectives. For example, it will not be possible with a monthly time step model to determine the contribution to increased. spring peak flows that can be expected from' implementing a specific alternative for providing more water to the fish. In order to determine the contribution to the spring peak, a daily time step will probably be'necessary. Furthennore. in order to detennine whether an alternati....-e will violate a channel flow capacity constraint (e.g. the 1100 cis on the Fryingpan below Ruedi) it will be necessary to have flow dara on a daily basis. In both these examples, we would only need daIl)' flow da1a for a relatively sholt period (a few weeks, perbaps one month) and not for an entire )OW. ' The Service (February ~ 1999 memo from Hemy Maddux to Randy Seahohn) indicates there may be the need forsome'daily modeling in Ma)' and June. We v.ill first have to determine if the additional cost and brain damage associated with a daily time step model is worth the effort and, if the answer to this question is yes, how do we go about achieving a successful and