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U"lity  Climate  Resiliency  Study  for  the  Metropolitan  North  Georgia  Water  Planning  District  

August  27,  2015  

Georgia  Environmental  Conference  

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Outline  

•  Acknowledgements  •  Goals  of  U"lity  Climate  Resiliency  Study  •  Poten"al  Future  Climate  Condi"ons  •  Methodology  and  Findings  for  Vulnerability  Analysis:  

 •  Infrastructure  and  Policy  Adapta"on      •  Summary    

Flooding Water Supply Water Quality Water Demand

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Acknowledgements  •  MNGWPD  

–  Andy  Cornwell  –  Chris  Faulkner  –  Danny  Johnson  –  Neela  Ram  –  BenneJ  Weinstein  –  Katherine  Zitsch  

•  Georgia  EPD  –  Liz  Booth  –  Lebone  Moe"  

•  GEFA  •  Cherokee  County  

•  Clayton  County  Water  Authority  •  Douglasville/Douglas  County  

Water  and  Sewer  Authority    •  Forsyth  County  •  GwinneJ  County  •  Henry  County  •  Rockdale  County  •  TCC  and  BAC  Members  •  CDM  Smith  Team  Members  •  UMass  Amherst  –  Dr.  Richard  

Palmer  

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Goals  of  U"lity  Climate  Resiliency  Study  

•  Produce  a  plan  for  the  District  that  can  be  used  to  guide  future  planning  efforts  

•  Assess  poten"al  vulnerability  of  water  resources  and  related  infrastructure  given  poten"al  climate  condi"ons  in  the  future:      –  Not  Predic>ve:  The  purpose  was  NOT  to  predict  future  climate  condi"ons  or  the  likelihood  that  certain  condi"ons  could  occur.      

–  Readiness:  The  purpose  WAS  to  iden"fy  poten"al  climate  condi"ons  that,  if  they  do  occur,  could  create  specific  risks.  

 

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Possible  Future  Climate  Condi"ons  

HOT/DRY HOT/WET

WARM/WET WARM/DRY

5  representa"ve  scenarios  of  possible  future  climate  condi"ons  based  on  GCMs    1  addi"onal  scenario  developed  by  extending  historic  records  through  2050.    Goal  was  to  bound  the  possibili"es  

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Future  Climate  Scenarios:  Annual  Temperature  

0

10

20

30

40

50

60

70

80

1950 1960 1970 1980 1990 2000

Annu

al  Average  Te

mpe

rature  ('F)

Year

2050  Central  Tendency

2050  Hot/Dry

2050  Hot/Wet

2050  Warm/Dry

2050  Warm/Wet

2050  Historical  Trend

Historical  Observed

Range of  Annual  Temperature  Change:1  to  7  ºF

Also have daily data to assist with looking at seasonal trends

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Future  Climate  Scenarios:  Annual  Precipita"on  

0

10

20

30

40

50

60

70

80

1950 1960 1970 1980 1990 2000

Annu

alPrecipita

tion  (in

)

Year

2050  Central  Tendency

2050  Hot/Dry

2050  Hot/Wet

2050  Warm/Dry

2050  Warm/Wet

2050  Historical  Trend

Historical  Observed

Range of  Annual  Precipitation  Change:-‐2  to  +11  in/yr  

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METHODS  AND  FINDINGS  

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Analysis  of  Water  Demands:  As  a  func"on  of  Policy,  Economics,  and  Climate  

200    

250    

300    

350    

400    

450    

500    

Economic  Recession  

Level  1  Drought  Restric>ons  

Level  4  Drought  Restric>ons  

GA  Water    Stewardship  Act  

Dry Periods Wet Periods

Wat

er D

eman

d (M

GD

)

Preliminary Results

DeKalb, Fulton and Gwinnett Counties as Proxy

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Water  Demand:    Sensi"vity  to  Climate  via  Mul"variate  Regression  

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Long  Term  Poten"al  Impacts  of  Climate  Variability:  Per  Capita  Water  Use  (by  2050)*  

* Average increase, with all other factors unchanged.

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Tendency  toward  increased  drought  condi"ons  

Extreme Drought

Severe Drought

Moderate Drought

Mild Drought

Incipient Drought

Near Normal

Incipient Wet

Wet Spell

Unusual Wet Spell

Very Wet Spell

Extreme Wet Spell

Palmer Index

- 3.5 0 3.5

Up to 2049

2050 to 2100

Hot/Dry Warm/Dry Central Tendency

Hot/Dry Warm/Dry

Central Tendency Hot/Wet

Key Observations: •  Drought severity is influenced more

by changes in temperature than by precipitation

•  Drought conditions and drought impacts are not necessarily the same: Storage can help.

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Water  Supply:    Evaluated  Firm  Yield  of  5  Small/Midsize  Reservoirs  

Reservoir   County  Storage  Volume  (BG)  

Drainage  Area  

(sq.mi.)  

Percent  watershed  developed  

Es>mated  Average  Flow  (cfs)  

Dog  River  Reservoir   Douglas   1.9     78.3   15.4   117  

Randy  Poynter  Reservoir   Rockdale   5.4     47.0   38.5   78  

Long  Branch  Reservoir   Henry   1.5   4.3   8.3   5  

Gardner  Reservoir   Henry   0.7   16.9   35.9   21  

Upper  Towiliga  Reservoir   Henry   6.0   29.4   13.1   40  

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Firm  Yield  In  Case  Study  Reservoirs  

0

5

10

15

20

25

30

35

Dog  River Randy  Poynter Gardner Long  Branch Cole/TawiligaFIR

M  YIELD  (M

GD)

Potential  Impacts  of  Climate  Trends  on  Firm  Yield

Central  Tendancy Hot  Dry Hot  Wet Warm  Dry Warm  Wet Trend  Projection Historic

•  Climate  trends  could  change  reservoir  yield  by  -‐10%  to  +  30%.  •  Drought  severity  does  not  always  equal  the  impact:  

–  Large  reservoirs  are  more  sensi"ve  to  long-‐term  droughts.  –  Small  reservoirs  can  be  more  sensi"ve  to  short  severe  droughts.  

•  No  clear  physical  predictors  of  risk  level  •  Changes  in  yield  would  be  coupled  with  increased  demand.  •  Important  to  understand  the  risks  for  each  individual  supply,  

and  manage  supply  and  demand  together    

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Water  Quality:    Evaluated  4  Case  Study  Rivers  for  Dissolved  Oxygen  

Select  Watersheds  

                               

Simulate  DO:  Exis>ng  GA  DOSAG  Models  

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•  All  climate  trends  suggest  water  temperature  is  likely  to  increase.  –  From  <  0.5oF  to  almost  3oF.  

•  Changes  in  dissolved  oxygen  were  es"mated  as  a  func"on  of  changing  temperatures  and  changing  low  flows  –  D.O.  reduc"ons  could  range  from  ~0  to  -‐1.4  mg/l  during  low  flow  (Ref:  State  standards:  4  –  5  mg/l)  

•  Could  impair  aqua"c  habitat  •  Could  affect  effluent  standards      

Water  Quality  Modeling  Results:    Water  Temperature  and  Dissolved  Oxygen  

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Flooding:  Evaluated  2  Case  Study  Watersheds  

 

Land  Use  Flint  River  Watershed  268  sq.  mi.  

Yellow  River  Watershed  127  sq.  mi.  

Residen>al   35%   60%  

Agriculture   14%   1%  

Commercial/  Industrial   8%   18%  

Forest   24%   8%  

Other   18%   13%  

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Projected  Percent  Changes  in  ARI  Depths  

•  Floods  that  occur  every  5,  10,  and  25  years  will  likely  intensify  •  This  is  true  for  wet  and  dry  scenarios  (rainfall  can  be  

redistributed):  

•  Important  to  consider  this  in  bridge,  culvert,  channel  design.  •  Green  infrastructure  could  help  aJenuate  some  peak  flows.      

Hot/Dry   Warm/Wet  

Rainfall  Depth   +  4%  to  +  12%   +  1%  to  +7%  

Peak  Streamflow   +  6%  to  +  11%   +  2%  to  +7%  

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INFRASTRUCTURE  AND  ADAPTATION  

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Water  Facili"es  Risk  Scorecard  Example:    Wastewater  Treatment  Plants    

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Example  of  Adapta"on  Recommenda"ons:  Wastewater  Treatment  Plants  

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Example  of  Adapta"on  Recommenda"ons:  Water  Treatment  Plants  

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CONCLUSIONS  AND  RECOMMENDATIONS  

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Review  of  Findings  

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Key  Findings  

•  Water  Supply:      –  Drought  severity  will  likely  increase.  –  Test  case  reservoir  yield  could  decrease  by  10%  or  increase  by  up  to  30%.  –  Climate-‐Influenced  Demands  will  likely  increase.  –  Each  u"lity  should  manage  supply  and  demand  together,  based  on  their  own  

unique  risks.  •  Low  Flows,  Water  Quality,  and  Drought  Severity:    

–  More  sensi"ve  to  temperature  than  to  precipita"on  –  Most  scenarios  indicate  a  worsening  of  these  condi"ons  

•  Flood  Intensity  will  likely  increase,  and  infrastructure  designs  should  consider  this  likelihood  

 

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Near  Term  Recommenda"ons  

•  Establish  climate  tracking  protocols  and  iden"fy  trigger  levels  for  adap"ve  measures.  

•  Incorporate  preemp"ve  adapta"on  measures  –  Drought  Management:  Understand  water  supply  risk  at  each  source,  and  manage  supply  and  demand  conjunc"vely  

–  Green  infrastructure:  •  Help  aJenuate  high  flows  •  Help  aJenuate  pollutant  loads  •  Poten"ally  help  regulate  baseflow  

•  Consider  recommenda"ons  from  study  when  upda"ng  local  master  plans  

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QUESTIONS?