|
<br />- 4,
<br />
<br />region, such as the Cherry Creek Drainage Basin, This approach uses actual observed rainfall data and takes into
<br />consideration those factors such as orographic and moisture inflow barriers, whereas the NWS approach uses
<br />generalized regional data,
<br />
<br />Mr, Lou Schreiner asked if this site-specific approach could then be even more specific in a region smaller than the Cherry
<br />Creek Basin, He added that the NWS would have a hard time agreeing with this method at this time, Dr. Tomlinson replied
<br />that the A W A approach would apply specific restraints where it is necessary, Mr, Schreiner asked if A W A was using the
<br />implicit storm transpositioning method as is COmmon with studies done by the NWS, He mentioned that the NWS has been
<br />using this implicit method in all of their HMR generalized reports and that the US Bureau of Reclamation adopted this
<br />method in the 1970s, He went on to say that A W A would end up "butting heads" with the NWS over this implicit
<br />transpositioning issue, Dr. Tomlinson explained to the attendees that implicit transpositioning means that the largest storms
<br />in a particular region are analyzed and those PMP values can have an adjusting effect on storms that occur outside of the
<br />transposition limits of the largest storm,
<br />
<br />Dr, Tomlinson went on to point out some differences between the NWS method of analyzing storms, such as those found
<br />between the 1935 Cherry Creek / Hale and 1965 Phun Creek Storms, He said that in 1935, there occurred numerous storm
<br />centers and each center was analyzed separately from the rest, so therefore, each center was identified as a different storm,
<br />But, he added, in 1965, there were also numerous storm centers, but unlike 1935, the entire storm, which ranged from Denv(
<br />to northern New Mexico and Western Kansas, was analyzed as a single storm, therefore creating misleading depth,area
<br />calculations, Mr, Schreiner replied that the 1965 Holly center was the original storm event that was studied by the USACE,
<br />and that the centers around the Palmer Divide were not analyzed at that time, He added that if a depth,area,duration is
<br />calculated for the Plum Creek center (near the Pahner Divide), one will get the controlling PMP values for storms ofvery
<br />short durations - measured in hours and not days, He then asked if A W A had the ,NWS Part I & II reports for the original
<br />1965 storm event. Dr, Tomlinson and Mr, Williams replied that they did not believe that these reports were part of the
<br />Freedom ofInformation Act request delivery from the NWS, Dr. Tomlinson went on to mention that the 1965 storm actuall:
<br />involves numerous centers in Colorado, New Mexico and Kansas, and that each center needs to be analyzed separately as nc
<br />to cause any misrepresentation of number in the storm analysis,
<br />
<br />Mr, William Miller asked if the NWS is going to review Interim Reports #1 and #2 based upon the original HMR PMP
<br />parameters, or if they are going to address questions that open up issues that involve basic HMR philosophy, Mr, Lang
<br />replied that the CWCB is looking at the parameters that were utilized in the originaLPMP determination, and then will decid,
<br />whether or not the contractor (AW A) has applied these parameters to their PMP study, He added that if the NWS was not
<br />impressed with the new PMP study, the CWCB will ask the USACE if they are, and if the USACE is not impressed, then th(
<br />PMP study would be passed on the congress to see that they think, He also stated that the new PMP study is not going to be
<br />solely based on the HMR PMP philosophy, but it will be addressing some of the same storm events, Mr, Miller then asked i
<br />the NWS had submitted their comments on Interim Report #1, and how will those comments be addressed, Mr, Lang said
<br />that the NWS would be sending their comments on that report very soon and they would be addressed accordingly at that
<br />time, Dr. Tomlinson stated that A W A is documenting all processes of the new PMP study so that the NWS knows exactly
<br />what is going on in the new study,
<br />
<br />Mr, Schreiner mentioned that a lot of historic storms have come very close to the PMP values, such as the one that occurred
<br />in Yankeetown, Florida, This, he added, was the reason why the US Bureau of Reclamation adopted the NWS method of
<br />implicit storm transpositioning, At this time, Mr, Lang interjected that the NWS has been contracted under a specific scope
<br />of work, and that the NWS is going to act as a professional agency, like the rest of the TRC. He added that the NWS is goin
<br />to give a professional opinion, but it is not known at this time if they are going to relate that professional opinion to their ow
<br />in,house PMP procedures, He stated that the NWS originally wanted to have veto power over this new study, but that
<br />request was denied by the CW CB.
<br />
<br />Mr, Schreiner stated that the USBR did not have the luxury of being able to analyze the newest and biggest storm events at
<br />the time of the Gibson Dam incident, for example, Mr, Lang said that A W A is analyzing these new big storm events and wiJ
<br />apply them directly to the Cherry Creek Drainage Basin in a manner that is "regional verses generaL" Dr, Tomlinson stated
<br />that the NWS is reviewing the new PMP study as a site,specific study and not as a piece or variation of an existing HMR, H
<br />
<br />Flood Protection. Water Project Planning and Financing. Stream and Lake Protection
<br />Water Supply Protection. Conservation Planning
<br />
|