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

Figure 12. 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.
Jan -May MEI vs. Days with 0.10" of precipitation or greater for Cortez for the period of
May 1 to Sept 15 (Average —12 days)
♦
♦
♦
O ♦ ♦
.t f
3s
a
♦ N
-3.00 -2.50 -2.00 -1.50 -1.00 -0.50 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50
Jan -Mar MEI Value
E - Stream flow (April — September)
For this critical component of the hydrological cycle, the District boundaries were
not so much adhered to as there was a HCI- stream flow analysis of the three major
drainages in this District. The stream gage points that were analyzed were the San Juan
River at Pagosa Springs, the Animas at Durango and the Dolores River at Rico. All of
these rivers do not effectively `merge' in the Colorado River system until they have left
the state boundaries and were analyzed separately.
San Juan at Pnosa Sprints
An analysis of the leading mode HCI relationships do indicate that the ENSO
HCI's maintain a general El Nino — more runoff/ vice versa relationship. However, the
AMO was a statistically more robust relationship than the ENSO variable. The initial
thought is to this is that El Nino years still have a higher level of scatter in parts of the
relationship. Examples of this relationship are presented in Figures 15 and 16.
22
♦♦
E - Stream flow (April — September)
For this critical component of the hydrological cycle, the District boundaries were
not so much adhered to as there was a HCI- stream flow analysis of the three major
drainages in this District. The stream gage points that were analyzed were the San Juan
River at Pagosa Springs, the Animas at Durango and the Dolores River at Rico. All of
these rivers do not effectively `merge' in the Colorado River system until they have left
the state boundaries and were analyzed separately.
San Juan at Pnosa Sprints
An analysis of the leading mode HCI relationships do indicate that the ENSO
HCI's maintain a general El Nino — more runoff/ vice versa relationship. However, the
AMO was a statistically more robust relationship than the ENSO variable. The initial
thought is to this is that El Nino years still have a higher level of scatter in parts of the
relationship. Examples of this relationship are presented in Figures 15 and 16.
22