The impact of accelerated sea level rise on coastal wetlands and its implications on storm surge - The story of lower Pascagoula River Basin in Jackson County, MS Wei Wu 1 , Maria Kalcic 2 , Jason Fleming 3 March 6, 2012 1. The University of Southern Mississippi 2. Computer Science Corp 3. Seahorse Coastal Consulting
Transcript
Slide 1
The impact of accelerated sea level rise on coastal wetlands
and its implications on storm surge - The story of lower Pascagoula
River Basin in Jackson County, MS Wei Wu 1, Maria Kalcic 2, Jason
Fleming 3 March 6, 2012 1.The University of Southern Mississippi
2.Computer Science Corp 3.Seahorse Coastal Consulting
Slide 2
GHGs are changing, but growing at a unprecedented accelerated
rate Atmospheric concentrations of CO 2, CH 4 and N 2 O over the
last 10,000 years (large panels) and since 1750 (inset panels).
Measurements are shown from ice cores and atmospheric samples (red
lines). The corresponding radiative forcing relative to 1750 are
shown on the right hand axes of the large panels. From IPCC Climate
Change 2007: Synthesis report
Slide 3
Surface temperature, seal level and snow cover are changing,
but at a unprecedented accelerated rate Observed changes in
a)Global average surface temperature; b)Global average sea level
from tide gauge (blue) and satellite (red); c)Northern hemisphere
snow cover for March-April. Smoothed curves represent decadal
averaged values while circles show yearly values. The shaded areas
are the uncertainty intervals. From IPCC Climate Change 2007:
Synthesis report
Slide 4
Consequences of climate change Alter ecosystem services and
affect the ability of biological systems to support human needs
(Vitousek et al. 1997) e.g. degradation in water quality,
productivity and extractable resources; Interact with other
environmental stressors: elevated acidic atmospheric deposition,
accelerated sea level rise, hurricanes etc.
Slide 5
Coastal wetland Coastal wetlands are ecologically, economically
and socially important to humans as they provide the benefits of
storm protection, flood control, habitat for commercially important
fisheries and wildlife, improved water quality through sediment,
nutrient and pollutant removal, recreation, and aesthetic value. In
particular, coastal wetlands can reduce storm surge potential by
acting as a physical barrier and creating frictional resistance for
the surge and waves. They may also reduce surge potential and
flooding risks by reducing surface winds due to higher sub-aerial
surface roughness and by slowing surge propagation due to bottom
friction in shallow flow at the inundation front.
Slide 6
Objectives Simulate the impact of different sea level rise
scenarios on coastal wetland; How the area and location changes of
coastal wetland affect storm surge predictions
Slide 7
Simulate the impact of SLR on coastal wetland
Slide 8
Method Sea Level Affecting Marshes Model (SLAMM 6.0.1 beta)
Simulates the dominant processes involved in wetland conversions
and shoreline modifications during long-term sea-level rise :
Inundation, Erosion, Overwash, Saturation, Accretion, Salinity
SLAMM integrates elevationsubmergence and wave action erosion.
SLAMM also incorporates a salinity algorithm, based on freshwater
discharge and cross-sectional area of the estuary, to model
saltwater intrusion in river-dominated estuaries of our study
domain. Model inputs included the USGS LiDAR-derived elevation data
(vertical accuracy: 12 cm) NOAA tidal data Accretion rates National
Wetlands Inventory (NWI) data
Slide 9
Study area lower Pascagoula River Estuarine 9 th American most
endangered rivers Latitude 3028N Longitude 8835W
Slide 10
Accretion rates Type of wetlandLocationSampling datesSediment
Accumulation (cm /y) Freshwater tidal marsh N 30 28 39.20 W 88 35
56.50 11/7/20090.45 0.20 Brackish marshN 30 26 5.46 W 88 35 19.14
4/25/20100.51 0.30 Salt marshN 30 2145.85 W 88 36 35.28
10/7/20100.30 0.19 From fallout radionuclides ( 7 Be, 137 Cs, and
210 Pb)
Slide 11
Sea level rise scenario Sea level rise rate is predicted to be
0.10 inch/year to 0.83 inch/year, on Mississippi Gulf Coast, which
will be translated to 0.26 m to 2.19 m increase in sea level from
1996 to 2100.
Slide 12
High sea level rise scenario
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Low sea level rise scenario
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Landscape metrics 19962100 under high SLR 2100 under low SLR
Edge density685.0268377.5212841.2947
Perimeter/Area14285.714310714.285711904.7619 Contiguity
index0.08330.1667 Aggregation index90.427394.728888.2405 Patch
richness density 0.03160.0380 Shannons diversity index
1.48080.96201.5657
Slide 27
High low From 1996 to 2100
Slide 28
Low vs. High sea level rise scenario in 2100
Slide 29
Simulate the impact of changes in coastal wetland on storm
surge
Slide 30
Method Advanced CIRCulation (ADCIRC model). Sea, Lake, and
Overland Surges from Hurricanes (SLOSH) model: domain is limited
and the spatial resolution is very coarse (0.5-7 Km) (International
Hurricane Research Center, online). It is difficult to simulate
convoluted shorelines and incorporate features that block or
accelerate storm surge flooding. In addition, tide and wave set ups
are not included, and the overland flooding model is not adequate,
thus SLOSH tends to produce large uncertainty and provides only a
very rough estimate in the predicted flooded area only. ADCIRCs
domain is flexible, its spatial resolution can reach finer than
5050 m, it can simulate convoluted shorelines and include features
like highways and canals, and it contains tide setup, so it
performs better (albeit more slowly) than SLOSH, especially at the
shoreline.
Slide 31
Mesh and bathymetry
Slide 32
Storm surge 1996
Slide 33
Water elevation in 1996
Slide 34
Water elevation in 2100 under high SLR scenario
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Water elevation in 2100 under low SLR scenario
Slide 36
1996
Slide 37
2100 under high SLR scenario
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2100 under low SLR scenario
Slide 39
Conclusion SLR is likely to affect area and distribution of
coastal wetlands and therefore alter landscape patterns. Wetland
change due to SLR is likely to change storm surge height (e.g. 1.8
-8.5% increase under different scenarios of SLR) and affect the
pattern of coastal floods (increase the flooded area).
Slide 40
Acknowledgements Mississippi-Alabama Sea Grant Consortium
Program Development Mississippi-Alabama Sea Grant Consortium
Coastal Storm Program