Hydroclimatology of the PNW and the Columbia River Basin

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Hydroclimatology of the PNW and the Columbia
River Basin JISAO Climate Impacts Group Nate
Mantua Alan F. Hamlet Dennis P. Lettenmaier
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Climate
Hydrology
Water Resources
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Wind
Rl
Precip
Temp
Rs
Climate
SST
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Snowmelt
Hydrology
Evapotranspiration
Orography
Vegetation
Runoff
Groundwater
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Water Resources
Recreation
Water Supply
Irrigation
Hydropower
Flood Control
Navigation
Fisheries
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Hydrologic Sensitivities of PNW
Snowmelt-Dominated River Basins to
Meteorological Changes
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No Change
No Change
Sm. change
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No Change
Sm. change
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Observed Variability of Columbia Basin Streamflow
Associated with PDO and ENSO
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Effects on Columbia Basin Hydrology Associated
with Interactions Between the PDO and ENSO
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Climate Patterns Associated with Extended
Low-Flow Sequences in the Columbia River
Basin Kristyn Gray Alan F. Hamlet
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• Definition of Extended Drought
• For each calendar month the virgin flow at The
  Dalles must be 0.9 std deviations or more below
  the long-term mean, and not exceed that threshold
  for longer than 3 sequential months at any time
  during the sequence.
• The sequence of low-flow must be more than 12
  months long
• Extended Drought Sequences 1900-1997
• Feb 1905--Jun 1906
• Dec 1928--Feb1932
• Oct1935--Aug1937
• Jan1944--Aug1945
• Jun1987--Sep1988
• May1992--Oct1995

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1944-1945
1905-1906
1987-1988
1928-1932
1936-1937
1992-1995
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• Climate Statistics for Extended Droughts
• 5 out of 6 are in PDO Positive Epochs
• 4 out of 6 contain multiple El Nino events
• 3 out of 6 contain back-to-back El Nino events