Recent hydrologic change in a rainfalldriven. Everglades swamp. Shawn E. Clem. Michael J. Duever Natural Ecosystems

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1 Recent hydrologic change in a rainfalldriven Western Everglades swamp Shawn E. Clem Western Everglades Research Center Corkscrew Swamp Sanctuary sclem@audubon.org Shawn E. Clem Michael J. Duever Natural Ecosystems mikeduever@naples.net RJ Wiley

2 Fort Myers Naples Corkscrew Swamp Sanctuary

3 Rainfall driven (near top of watershed) Mosaic of hardwood hammock, pine flatwoods, marsh, wet prairie, pond & bald cypress habitats Largest remaining intact bald cypress forest Site of historically largest Wood Stork colony in N. America

4 RAINFALL SURFACE WATER Staff Gauges GROUNDWATER Well (C-492) km

5 Median daily surface water elevation (m NGVD29) s Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Date

6 Median daily surface water elevation (m NGVD29) s Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Date

7 Median daily surface water elevation (m NGVD29) s Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Date

8 Median daily surface water elevation (m NGVD29) s Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Date

9 Median daily surface water elevation (m NGVD29) s Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Date

10 Median daily surface water elevation (m NGVD29) s Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Date

11 CHANGE IN RAINFALL & PEAK WATER LEVELS No decadal variation in annual, wet season, dry season or monthly rainfall totals No change in magnitude (5.62 m NGVD29) or date (September 18) of annual wet season peak water level Average Rainfall (cm) s 1970s 1980s 1990s 2000s 2010s

12 (cm NGVD29) Hydroperiod: Maximum number of contiguous days habitat was inundated each hydrologic year (max=365) Hammock Forest Pine Forest Wet Prairie/Scrub/Dwarf Cypress Freshwater Marsh/Pond Cypress Mixed Swamp/Bald Cypress Pond 450 cm 420 cm

13 (cm NGVD29) Hammock Forest Pine Forest Wet Prairie/Scrub/Dwarf Cypress Freshwater Marsh/Pond Cypress Mixed Swamp/Bald Cypress Pond 450 cm 420 cm No decadal change in hydroperiod HP=10 d HP=61 d HP=133 d

14 (cm NGVD29) Hammock Forest Pine Forest Wet Prairie/Scrub/Dwarf Cypress Freshwater Marsh/Pond Cypress Mixed Swamp/Bald Cypress Pond 450 cm 420 cm

15 Hydroperiod (days inundated) Freshwater marsh Bald cypress Pond 1960s 1970s 1980s 1990s 2000s 2010s Decade 1960s to 2010s: 47.1% (4.2 mo.) 33.7% (3.5 mo.) 22.8% (2.5 mo.)

16 (cm NGVD29) Hammock Forest Pine Forest Wet Prairie/Scrub/Dwarf Cypress Freshwater Marsh/Pond Cypress Mixed Swamp/Bald Cypress Pond cm No decadal change in hydroperiod, but cm Pre- vs Post-2000 is significant

17 11/30-12/13 12/14-12/27 12/28-01/10 01/11-01/24 01/25-02/07 02/8-02/21 02/22-03/07 03/08-03/21 Average water level recession rate (mm/d) CHANGE IN DRY SEASON RECESSION RATES WY1960-WY1999 WY2000-WY > 2X Bi-weekly period

18 Cumulative days dry in bald cypress (water level 5.05 m NGVD29) TIMING OF CHANGES 4000 m = R 2 = Baseline Slightly shorter hp ( rainfall): m = R 2 = m = R 2 = m = R 2 = m = 43.6 R 2 = m = 150 R 2 = Reduced hydroperiod years ( rainfall): Hydrologic Year Dry 4.5x longer despite typical rainfall: 2006-present

19 Cumulative days dry in bald cypress (water level 5.05 m NGVD29) TIMING OF CHANGES Hydrologic Year

20 Cumulative days dry in bald cypress (water level 5.05 m NGVD29) TIMING OF CHANGES No nesting 13% of years No nesting 78% of years No Wood Stork nesting at Corkscrew Hydrologic Year

21 Landscape Changes Potentially Impacting Hydrology Increase in agriculture (esp. citrus) and associated water management activities

22 Landscape Changes Potentially Impacting Hydrology Increase in agriculture (esp. citrus) and associated water management activities Increased efficiency of canals

23 Population Increase in agriculture (esp. citrus) and associated water management activities Landscape Changes Potentially Impacting Hydrology Increased efficiency of canals Increased residential & municipal water use (well fields) 700, , , ,000 Lee 11X 300, ,000 Collier 20X 100, Year

24 Landscape Changes Potentially Impacting Hydrology Increase in agriculture (esp. citrus) and associated water management activities Increased efficiency of canals Increased residential & municipal water use (well fields) All of the above

25 Conclusions Hydrology has markedly changed at Corkscrew Swamp Sanctuary Recent wet season hydrology is similar to what has been seen throughout our POR Dry season water levels are falling faster than they did historically, resulting in significantly shorter hydroperiods Changes are most apparent beginning in 2006, but more subtle changes may be apparent beginning in the late 1980s Additional work is needed to determine geographic extent, to pinpoint cause/effect, and to determine effects on native vegetation and wildlife Long-term monitoring of natural areas should not be overlooked/underfunded

26 Special Thanks-- 60 years of Corkscrew Swamp Sanctuary staff & volunteers Corkscrew Science Advisory Committee (JJ Lorenz, WF Loftus, B Cornell, J Lauritsen) Various family foundations and other donors