WMOD00274 ‎(2)‎

• Title: Hydro-Climate Index Study - Final Report
• Prepared By: HDR Engineering
• Date: 2/14/2008
• County: Statewide
• State: CO
• Weather Modification - Doc Type: Report

Lower Arkansas:
In the lower reaches of the Upper Arkansas River the PDO and the AMO were the
most notable factors that held some value in multi-seasonal wintertime precipitation.
Positive PDO years tend for wetter weather as does positive AMO values (note: that is
opposite of many of the basins described in this report.).
April to September Precipitation:
Upper Arkansas:
In the far upper reaches of the Arkansas the PDO and the AMO were the most
notable factors that held some value in multi-seasonal wintertime precipitation. Negative
PDO years tend for wetter weather as does positive AMO values (note: that is opposite of
many of the basins described in this report.).
Middle Arkansas:
In the middle reach of the Upper Arkansas the PDO and the MEI were the most
notable factors that held some value in multi-seasonal wintertime precipitation. Negative
PDO years tend for wetter weather as does positive MEI values (i.e. La Nina leans
towards wet weather).
Lower Arkansas:
In the lower reaches of the Upper Arkansas River the PDO and the AMO were the
most notable factors that held some value in multi-seasonal wintertime precipitation.
Positive PDO years tend for wetter weather as does positive AMO values (note: that is
opposite of many of the basins described in this report.).
Naturalized April-July Stream flow:
Upper Arkansas:
The one factor that held some consistent influence on the upper stretch of the
Arkansas River was the PDO. However, the statistics are mixed when one examines the
exact correlations. ENSO exhibited a minor trend however, this may be insufficient for
planning purposes.
Middle Arkansas:
For the stretch of the river that includes Chafee County, the relationships with
two-year peak stream flow and HCI was similar to the upper section. Unlike the upper
section, the PDO relationship however, this appears to be potentially skewed by a handful
of years of high flow with negative PDO values. ENSO also exhibited a minor trend
however, this may be insufficient for planning purposes.
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