Final.HCI.Report.HDR

• Title: Hydro-Climate Index Study
• Prepared For: CWCB & Colorado River WCD
• Prepared By: HDR Engineering Inc.
• Date: 12/28/2007
• County: Statewide
• State: CO
• Country: USA
• Weather Modification - Doc Type: Scientific Study

Table of Contents
Introduction......................................................................................... ..............................1
Background......................................................................................... ..............................1
Data..................................................................................................... ............................... 3
PreliminaryResults ........................................................................... ............................... 6
UserGuide .......................................................................................... ............................... 6
Division3 (Rio Grande Basin) ........................................................... ............................... 7
Division7 (San Juan /Dolores) ........................................................... .............................17
Multiyear Relationships: ................................................................................................ 34
(Upper Colorado - Division 41 Gunnison — Division 51Yampa -White Division 6) .......... 34
Figures
Figure 1. Generalized impacts of the ENSO phenomenon on North America for the
January -March time frame (courtesy of NOAA/Climate Prediction Center)....... 2
Figure 2. Map of the six HCI's and regions where they are measured ............................... 4
Figure 3. Map of Water Division 3 (Rio Grande River) and subsequent division
boundaries.............................................................................. ............................... 8
Figure 4. Relationship of the Sept. - Nov. NAO vs. District 20 Dec. -Mar. Basin Avg.
Precip.................................................................................... ............................... 10
Figure 5. Relationship of the Sept. - Nov.PDO vs. District 35 Dec. -Mar. Basin Avg.
Precip.................................................................................... ............................... 11
Figure 6. April - June Precipitation in District 26 vs. the preceding November - January
PDOvalue ............................................................................ ............................... 12
Figure 7. Comparison of April- September naturalized stream flow at Saguache Creek.. 14
with the preceding August- October AMO values ................ ............................... 14
Figure 8. Comparison of April- September naturalized stream flow at Saguache Creek. 15
with preceding August - October AMO values ...................... ............................... 15
Figure 9. Relationship between the NAO and a summation of naturalized stream flow in
Costilla County (District 35) ................................................ ............................... 16
Figure 10. Map of Colorado Water Division 7 and its administrative districts ............... 18
Figure 11. Relationship of the Jul -Nov. SOI vs. District 71 Dec. -Mar. basin avg.
precip.................................................................................... ............................... 19
Figure 12. Relationship of the Jan -Mar. SOI vs. District 34 Apr. -Jun. Basin Avg.
Precip.................................................................................... ............................... 20
Figure 13. Relationship of the Mar -May. PDO vs. District 32 Jun. -Sep. Basin Avg.
Precip.................................................................................... ............................... 21
Figure 14. Relationship between the March -May MEI and the number of days with 0.10"
of precipitation or greater in the May 1- Sept 15 period ...... ............................... 22
Figure 15. Relationship between the preceding July -Sept. MEI vs. the following Apr. -
Sept. naturalized stream flow for the San Juan River at Pagosa Springs............ 23
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