Technical Oversight CommitteeSeptember 14, 2011

Briefing on the g2010 – 2011 Drought in South Florida

Wossenu Abtew Ph D P E D WREWossenu Abtew Ph D P E D WREWossenu Abtew, Ph.D., P.E., D.WREPrincipal Engineer, Water Quality BureauWossenu Abtew, Ph.D., P.E., D.WRE

Principal Engineer, Water Quality Bureau

Factors Determining the Severity of a Droughtof a Drought

Rainfall Amount

Rainfall Temporal Distribution

Rainfall Spatial Distribution

Antecedent Hydrologic Condition Antecedent Hydrologic Condition

Spatial Variation of Annual Rainfall with Temporal Extremes (100-year return periods)Temporal Extremes (100-year return periods)

Monthly Variation of WY2011 and Historical Average RainfallHistorical Average Rainfall

)

Most months had far below average rainfall

ly ra

infa

ll (in

)

8

10

WY2011historical average

October rainfall was a 1-in-100 yr drought

Upper KissimmeeL Ki i

erag

e m

onth

l

6

Lower KissimmeeLake OkeechobeeMartin/St. LuciePalm Beach

hist

oric

al a

ve

4

WY2

011

and

h

0

2

2010 - 2011

May June July Aug Sept Oct Nov Dec Jan Feb Mar Apr

W 0

Driest 3-month Rainfall since 1895(October through December 2010)(October through December, 2010)

WY2011 Rainfall Deficits and Return Periods by Rain AreaPeriods by Rain Area

Return Period is expectedfrequency or recurrence intervalfrequency or recurrence intervalReturn Period  in 

yearsProbability of being 

exceeded in any year (%)5 2010 1020 520 550 2100 1

Palmer Drought Severity Index (July 2011)Palmer Drought Severity Index (July 2011)

South Florida EvaporationDrought severity increases by increasing EvaporationDrought severity increases by increasing Evaporation

Water Conservation Area 1 Inflows

Water Conservation Area 3 and S333 Headwater StagesHeadwater Stages

10.0G

VD

29)

9.0

9.5

10.0ai

ly s

tage

(ft N

G

7 5

8.0

8.5

Ave

rage

da

6.5

7.0

7.5

WCA 3 average stageS333 headwater stage WCA3 floor

1/1/

2011

2/1/

2011

3/1/

2011

4/1/

2011

5/1/

2011

6/1/

2011

7/1/

2011

8/1/

2011

9/1/

2011

6.0

Date

S333 Headwater Stage (record low in the last 20 years)(record low in the last 20 years)

13N

GVD

29)

11

12

13ily

sta

ge (f

t N

8

9

10

Ave

rage

da

6

7

8

June 8th, 2011

01/0

1/90

01

/01/

91

01/0

1/92

01

/01/

93

01/0

1/94

01

/01/

95

01/0

1/96

01

/01/

97

01/0

1/98

01

/01/

99

01/0

1/00

01

/01/

01

01/0

1/02

01

/01/

03

01/0

1/04

01

/01/

05

01/0

1/06

01

/01/

07

01/0

1/08

01

/01/

09

01/0

1/10

01

/01/

11

01/0

1/12

5

Date

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

El Niño Southern Oscillation Prediction with Cumulative Sea Surface Temperature IndexCumulative Sea Surface Temperature Index

Cumulative SST Index (Abtew and Trimble 2010; Abtew et al 2009)

Abtew, W. and P. Trimble. 2010. El Niño Southern Oscillation Link to South Florida Hydrology and

(Abtew and Trimble, 2010; Abtew et al., 2009)o C

) 10

15

strong El Niño

Hydrology and Water Management Applications. Water Resources Management, 24(5):4255‐4271, DOI:10 1007/s1126 SS

T In

dex

(o

0

5El Niño 2009

DOI:10.1007/s11269‐010‐9656‐2.

Abtew, W., A. Melesse and T. Dessalegne. 2009. El Niño Southern 

Cum

mul

ativ

e

10

-5

t L Niñ

La Niña

2008

20112010

Oscillation link to the Blue Nile River Basin Hydrology. Hydrological Processes. Vol. 23:3653‐3660; 

M th

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

C

-15

-10 strong La Niña

DOI:10.1002/hyp.7367.

Month

What does La Niña Mean for the Everglades Protection Area?Everglades Protection Area?

Reduced inflowsL t l l Lower water levels

More wildfires Less water quality sampling events in

the EPA

Hydrology Impact on Number of Sites Sampled (Refuge Monitoring, 1994-2011)(Refuge Monitoring, 1994 2011)

• The 2011 number of sites in the Refuge that were not sampled due to low stagesthat were not sampled due to low stages is the highest since 1994

• In calendar year 2011 (through July), there were 59 events with no sampling

Droughts and Wildfire (Water Conservation Area 1 5/7/11)(Water Conservation Area 1, 5/7/11)

Dry Conditions in Water Conservation Area 2 (5/4/11)Area 2 (5/4/11)

Summaryy

WY2011 d ht d WY2011 was a severe drought year and WY2012 is likely to be another dry yearH d l i diti i t t lit Hydrologic conditions impact water quality sampling and parameter concentrationsI t ti R f d P k TP Interpreting Refuge and Park TP compliance must take antecedent and prevailing hydrology into accountprevailing hydrology into account