Modeling Coastal Erosion

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Modeling Coastal Erosion Near Barrow, Alaska
Preliminary Results
Scott D. Peckham, William Manley, Mark Dyurgerov
and James Syvitski
INSTAAR, University of Colorado, Boulder
Arctic Coastal Dynamics 2nd Workshop November 27,
2001, Potsdam, Germany
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This coastal erosion modeling project is part of
a larger NSF Arctic System Science (ARCSS)
Program project entitled An Integrated
Assessment of the Impacts of Climate Variability
on the Alaskan North Slope Coastal
Region Principal Investigators Amanda Lynch,
Ronald Brunner, Judith Curry, James Maslanik,
Linda Mearns, Anne Jensen, Glenn Sheehan and
James Syvitski It is also part of HARC Human
Dimensions of the Arctic
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Preliminary DEM based on 1955 Barrow B-4 USGS
topo map. (William Manley Leanne Lestak)
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storm wind
Locations of key features near Barrow, Alaska.
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Delft3D is a fully-coupled suite of models FLOW,
WAVE, SED, MOR, WAQ PART
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The Main Modules of Delft3D
FLOW Module to solve for 3D hydrodynamic flow
field subject to prescribed
initial boundary conditions on a grid. SED
Module to model suspended sediment
transport. MOR Module to track changes to bed
morphology as a result of
flow-driven bed and suspended sediment
transport. WAVE Module to simulate nearshore
waves (SWAN) that result from
prescribed wind and bed roughness data. QUICKIN
Utility for importing manipulating
bathymetric data. RGFGRID Utility for creating
editing the orthogonal, curvilinear
grids that are used by the FLOW and WAVE
modules. GPP Utility for post-processing and
visualization.
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Preliminary DEM with Bathymetry for Barrow, AK
and Vicinity.
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Example of an Orthogonal Computational Grid for
the Flow and Sediment Transport Modeling
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Other Examples of Computational Grids
Hong Kong
North Sea
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Summary of Big Storms Near Barrow
October 3-5, 1963 Ice-free conditions near
Barrow. 3 million (1963 dollars) in reported
damage. Winds from due west. Average, Sustained
(1-min) and Peak wind speeds of 39, 55 and 75
mph. Estimated sediment transport of 200,000
cubic yards. Estimated wave heights of 10 ft
storm surge of 11 to 12 ft. Salt-water
contamination of Fresh Lake (NARL water
supply) (See Hume and Schalk (1967) for more
details.)
NOTE The prevailing wind direction for Barrow is
from E to ENE, with typical speeds of 11 to 12
mph. Normal daily tide is 6 inches.
August 10, 2000 Ice-free conditions near
Barrow. 7 million in reported damage. Winds from
due west. Average, Sustained (1-min) and Peak
wind speeds of 37, 55 and 64 mph. Estimated wave
heights of ???? Loss of dredge used for beach
nourishment.
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Observed Reduction in Sea-Ice Extent from 1979 to
1995
A reduction in sea-ice extent is expected to
increase the likelihood of coastal erosion and
damage from large storms. Even partial coverage
inhibits the formation of large waves.
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Base station (on top of the old theatre in the
NARL complex) used for the differential GPS
measurements. (William Manley Mark Dyurgerov,
2001)
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Using differential GPS to measure coastline
position. (Credit William Manley Mark
Dyurgerov)
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Annotated Aerial Photo of Barrow, Alaska
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Coastal bluffs southwest of Barrow.
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Differential GPS was also used to measure the
current position of the bluffs and to collect
data for high resolution DEMs of some bluff
faces. (Credit William Manley Mark Dyurgerov,
INSTAAR)
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Establishment of 63 Ground Control Points
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Conclusions
Although we are still in the early stages of this
work, it appears that Delft3D and associated
modules will allow us to model sediment transport
along the coast of Barrow, AK in response to
large storms such as those observed in October of
1963 and August of 2000. This will allow us to
quantify the cumulative effect of several such
storms, and to explore various mitigation scenario
s such as dredging and beach nourishment.
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The Main Modules of Delft CHESS
UNIBEST Longshore cross-shore sediment
transport model for predicting
shoreline evolution.
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