HR: 1340h
AN: H43A-0970    [Abstracts]
TI: Drought on the Colorado River: Is the most recent decade of low flows unusual?
AU: * Webb, R S
EM: Robert.S.Webb@noaa.gov
AF: NOAA ESRL Physical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AU: Pulwarty, R S
EM: Roger.Pulwarty@noaa.gov
AF: NOAA Climate Program Office, 1315 East West Highway, 12th Floor, Silver Spring, MD 20910, United States
AU: Dole, R M
EM: Randall.M.Dole@noaa.gov
AF: NOAA ESRL Physical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AB: Stakeholder and users, from water resource managers to governors, have begun to ask if the past decade of runoff patterns and streamflows levels in the upper Colorado River Basin are harbingers of the future climate changes. Over the last 10 years, the streamflow has been 83 percent of the average (1971-2000). Increasingly, users are posing questions about projected future changes in the context of past changes. Some of these questions include: Is this recent decade of flows a departure from long-term averages? And are similar conditions likely to persist into the future? To address these questions, we examine the 1998-2007 decade of Colorado River flows in context of several records: the 1964 to present unregulated inflow into Lake Powell, the 1896 to present natural flow at Lees Ferry estimates, and the 500+ year tree ring reconstructions of streamflow at Lees Ferry extrapolated to present. We test whether the means of various segments of the records are different than the means of the full records. We also test whether dry periods persist longer than would be expected from randomly derived sequences. Results are compared to similar analyses of drought risk in 500+ year tree ring reconstructions of streamflow. Our study underscores the importance determining the changing baselines that decision makers confront in planning for the future based on limited instrumental records and hydroclimatic systems in transition
DE: 1807 Climate impacts
DE: 1812 Drought
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 4920 Dendrochronology
SC: Hydrology [H]
MN: 2007 Fall Meeting