Impacts of climate anomalies on water resources in the Carolinas

Dan Tufford, Greg Carbone, Jim Hussey, Kirstin DowUniversity of South Carolina

Climate Prediction Application Science WorkshopChapel Hill, NC06 March 2008

Evaluating ENSO Impacts in the Carolinas

Stakeholders’ perceptions

of ENSO impacts

Discerning and

communicating

variability of ENSO

expression

Regional assessment• North and South Carolina• COOP and USGS

– 1950 – 2004

• Monthly total precipitation and streamflow• Assign ENSO phase by month (CPC)

– Cool (La Niña), neutral, warm (El Niño)

• Assign AMO phase by year– Warm – 1950-1963, 1995-2004– Cool – 1964-1994

• Each month assigned to a season– Winter = DJF, Spring = MAM, etc.

• SAS Proc GENMOD– Gamma distribution– Significance at p ≤ .05

ENSO and AMO analysis

ENSO phase AMO both AMO cool AMO warm Coastal effectWinter W/C

W/NN/C

Spring W/CW/NN/C

Summer W/CW/NN/C

Autumn W/CW/NN/C

Winter – AMO n/a

Precipitation Stream flow

Winter – AMO cool

Precipitation Stream flow

Winter – AMO warm

Precipitation Stream flow

ENSO and AMO analysis• Winter – warm AMO, both precipitation

and streamflow– El Niño > Neutral > La Niña

ENSO and AMO analysis• Winter – warm AMO, both precipitation and

streamflow– El Niño > Neutral > La Niña

• Spring – similar relationships– Not as strong as winter

• Summer – significant precipitation only– Both El Niño, La Niña > Neutral when AMO cool– Both El Niño, La Niña < Neutral when AMO warm

• Autumn – both precipitation and streamflow– Greater regional differences – interior v coastal– Differences between precipitation and streamflow

Influence of tropical storms

Dams R Us

• Analysis of only unregulated stations does not significantly alter the interpretation of the results.

• Suggests actual inflow to reservoirs impacts their operations as much or more than weather.

Uses of these results/methods• Hydrologic modeling

– Effect of interannual and multidecadal phase – Both short- and long-term scenarios

• Value of subregional analysis for water management and planning– Climate driven interannual weather patterns do vary

over the study area

• Provides another perspective of the impacts of land use change

• Streamflow is more important than precipitation for some sectors– Analysis may provide a basis for seasonal

differentiation among these sources of water

Regional drought implications

• Prior knowledge that La Niña is associated with dry winter conditions in the southeast

• These results show this effect is associated with the warm phase AMO

• Providing AMO and ENSO phases with monitor reports and seasonal forecasts would make them more information rich

Drought implications example

• Telephone surveys of horticultural industry in NC/SC

• “If drought continues residential planting will be minimal due to watering restrictions”

• Planting decisions are made months in advance– Influenced by an indirect

effect

• Some do their own monitoring to stay abreast of local conditions

Additional acknowledgements

• Jinyoung Rhee, PhD – USC Geography• Graduate students

– Kirsten Lackstrom, Richard Murphy, Sara Yorty

• Undergraduate students– Lauren Felker, Grandon Wilson