PREDICTING CLIMATE CHANGE IMPACTS ON WETLAND BOUNDARIES IN BENCHMARK SOILS. M. J. Vepraskas and C.P. Niewoehner, NC State University

Transcription

1 PREDICTING CLIMATE CHANGE IMPACTS ON WETLAND BOUNDARIES IN BENCHMARK SOILS M. J. Vepraskas and C.P. Niewoehner, NC State University

2 Is Climate Changing?

3 Columbia Glacier (Alaska) Source: NASA

4 +20 cm IPCC, 2007

5 Years before Present (x1000) Depth Below Present Sea Level (m) Today Sea Levels have been rising since end of Ice Age 35 Modified from: D. Meishner and A. C. Neumann, unpublished

6 Rising Sea Levels cause erosion of the Outer Banks (1.5 m/yr)

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8 Will Climate Change Impacts be felt here?

9 Will Climate Change Affect this Subdivision?

10 Soils in 2013 Wetland soils Upland soils Edge of wetlands and soils suitable for septic

11 Soils in 2070-Wetter Wetland soils Expand into Upland Upland soils Septic system fails

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13 Jurisdictional Wetlands must have: Hydrophytic Plants Hydric Soils Wetland Hydrology (today s focus) Soils are saturated within 30 cm of the surface for 14 days or more during the growing season in 5 or more years out of 10.

14 Objectives Illustrate how to: 1. Identify a climate change model whose predictions match measured rainfall well. 2. Use the model to compute water table levels in a wetland soil and upland soil through Estimate impacts of climate change on wetland boundaries

15 Daniels et al, 1999 Wet Flat Landscapes in the Coastal Plain Wet Flats

16 Soils monitored include both Wetland (Hydric) and Upland soils Upland Soils Lynchburg Wetland (Hydric) Soils with: Rains Wells in plots

17 Soil Plot Measurements 30 soil plots monitored and soil colors described at 5 sites Water table levels measured daily for 2 to 3 years. Soil properties (Ksat, pore size distribution) determined for major horizons

18 DRAINMOD was used to compute daily water table levels Drainage rate Restrictive Layer

19 Hydrologic Modeling DRAINMOD was calibrated for each soil where a well was installed Calibrated models were used to compute daily water table levels from 1951 through 2070.

20 Which Climate Model Should You Use? Climate change models predict rainfall and temperature from 1951 to We assumed that the model whose predictions matched measured precipitation values best, was the better model to use.

21 Climate Change Models Predict Temperature and Rainfall into the Future Three models were obtained from the U.S. Forest Service. Measured rainfall amounts from 1951 through 2000 were correlated with model predictions to identify the climate model giving the best fit.

22 METHODS Overview: a 4-Step Approach Calibrate model to predict water table levels from rainfall Determine how long soils saturate each year from Identify appropriate climate change model Compute ~60 yr of daily water table levels using Predicted rainfall data

23 R 2 values for measured vs. predicted rainfall for three models during the period Climate Model Decadal Data By Month Hadley: UKMO-HadCM USDC/ NOAA/ GFDL-CM Canadian Centre for Climate Modeling & Analysis CGCM ALL 0.57 Data for Pitt County, NC

24 Measured precipitation (mm) Hadcm3_a1b total decade precipitation by month 1951 through 2000 R² = Predicted Precipitation (mm) y = 0.9x + 134

25 Climate Change Impact on Wetlands: Duration of saturation occurring within 30 cm of surface Avg. Consec. Days/yr Wetland Soils (Rains) Hadley weather data Upland Soils (Lynchburg) Measured weather data Decade

26 Avg. Consec. Days/yr Current Wetlands will Exceed Minimum Requirements for Wetland Hydrology Wetland Soils 40 Minimum for wetland hydrology (14 d) Decade

27 Rainfall and ET (cm) Predicted changes in Rainfall and Temperature with time Rainfall Et Decade

28 Wetland boundary should remain unchanged until 2070 Upland Wetland Boundary Wetland

29 Changes in Precipitation (2080) UKMO-HadCM3, Medium emissions Wilmington Charleston Climatewizard.com

30 Preliminary Conclusions The Hadley model predicted historic rainfall well for Pitt County, NC. By 2070, climate change will not affect existing wetland boundaries (based on hydrology) Wetlands will dry up earlier in the year due to increases in Et. Future research will examine larger area

31 The End

32 Funding for this work has come from: For which we are thankful