Climate Change Considerations forSurface Water and Groundwater

Flows in the Everglades

Robert JohnsonNational Park Service/ENP

Hydrology of the Everglades in the Context of Climate Change

March 30, 2012

Climate Change Considerations forSurface Water and Groundwater

Flows in the Everglades

Robert JohnsonNational Park Service/ENP

Hydrology of the Everglades in the Context of Climate Change

March 30, 2012

Climate Variability and Water Management • South Florida rainfall patterns create alternating wet and dry

periods, which are difficult to manage.

• Stationary assumptions are no longer valid, making it harder to evaluate water resource demands and risks.

• Climate change predictions suggest increased rainfall variability, slightly drier wet seasons with increased tropical cyclone intensity.

• Knowledge Gap: Managing extreme rainfall events.

1,50

0

530

150

Current Water Budget (LORS/T3)

550

1,400

740

770

170

550230

470

550

800

950

Avg. Annual Flows in 1,000 ac-ft/yr

The Current Water Management System • The Central and Southern Florida

(C&SF) Project features are rather poor at retaining excess water following high rainfall periods.

• More than 3.5 million acre-feet of water is lost to tide in an average year, with 25% coming from Everglades seepage losses.

• The most viable options retaining this water are adjusting Lake Okeechobee operations, increasing flows into the Water Conservation Areas, and reducing groundwater seepage into the Lower East Coast.

• Each of these options create tradeoffs between flood control, water supply, and water quality.

The Impacts of Urban/Agricultural DevelopmentIn the Lower East Coast

• Total water use in Miami-Dade, Broward, and Palm Beach Counties increased from 875 to 2,147 MGD between 1965 and 2000.

• Average wet season groundwater levels declined by 1-3 feet (orange colors) from the 1940’s to the 1990’s.

Source: Impact of Anthropogenic Development in SE Florida, USGS, 2005.

Water Management in Lake Okeechobee• Lake Okeechobee inflows routinely exceed outflows, and high

Lake levels impact levee safety and damage the littoral zone.

• Lowering Lake levels creates harmful discharges to the northern estuaries, and significantly impacts regional water availability.

• Knowledge Gaps: Greater outflow flexibility, development of optimal long-term operations for sustainability.

Hurricanes Charley, Frances, Jeanne, Aug –Sept 2004

Hurricane Wilma, Oct 2005

Tropical Storm Fay, Aug 2008

RegulationSchedule Change

0

50

100

150

200

250

300

350

400

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

Mean

Mon

thly F

low (th

ousa

nd ac

-ft)

.

Average Everglades Protection Area Monthly Inflow Distribution

Current (~1400 kaf/yr)

CERP (~1700 kaf/yr)

NSRSM (~2100 kaf/yr)

20% Increase50% Increase

Water Flow Improvements in the Everglades• Improved wetland health and resilience is linked to increasing

water depths/flooding durations and soil accretion.

• Flow increases support Everglades restoration and water supply availability by redirecting excess flows currently going to tide.

• Knowledge Gap: Improved conveyance to allow sheetflow and rainfall-driven operations.

Increased Everglades Inflows via ReducedNorthern Estuary Regulatory Releases

Enhanced Everglades Inflows = Reduced Estuarine Harm

Current

Enhanced 40% Reduction

80% Reduction

Reducing Seepage Losses from the Everglades

Lox.NWR

WCA-2A

WCA-3A

Everglades Agricultural

Area

Strazzulla Wetlands

Modified WD, C-111 SD,C-111 SC

• Water Preserve Areas: Capture and store excess runoff from the Lower East Coast currently going to tide.

• ENP Seepage Mgmt.: Install a barrier to block groundwater seepage.

• Knowledge Gap: Determine the most cost effective method.

ENP Seepage Mgmt.

Seepage Barrier

Hard Layer (Q4)

Hard Layer (Q3)

1,410

190

75

Future Water Budget (CERPA)

720

1,700

1080

205

50

500

240

490

280

620

850

Avg. Annual Flows in 1,000 ac-ft/yr

The Post-CERP Water Management System

• Proposed CERP features would retain on average 950,000 acre-feet/year currently lost to tide.

• This would increase resilience of the water management system to climate variability, climate change, and sea level rise.

• The concern is that many of the original CERP water storage features (regional ASR, Lakebelt, Water Preserve Areas) are no longer considered viable.

• Knowledge Gaps: New storage approaches (Lake O./EAA/WCAs), and new optimization tools that maximize restoration benefits while enhancing long-term water sustainability for the built system.

50

240