Modeling Coastal Erosion Near Barrow, Alaska Scott D. Peckham, William Manley, Mark Dyurgerov and James Syvitski INSTAAR, University of Colorado, Boulder.

Modeling Coastal ErosionNear Barrow, Alaska

Scott D. Peckham, William Manley, Mark Dyurgerov and James Syvitski

INSTAAR, University of Colorado, Boulder

Arctic Coastal Dynamics 2nd WorkshopNovember 27, 2001, Potsdam, Germany

Preliminary Results

This coastal erosion modeling project is part of a larger NSFArctic System Science (ARCSS) Program project entitled:

An Integrated Assessment of the Impacts of ClimateVariability on the Alaskan North Slope Coastal Region

Principal Investigators:Amanda Lynch, Ronald Brunner, Judith Curry, JamesMaslanik, Linda Mearns, Anne Jensen, Glenn Sheehanand James Syvitski

It is also part of HARC: Human Dimensions of the Arctic

Preliminary DEM based on 1955 Barrow B-4 USGS topo map. (William Manley & Leanne Lestak)

Locations of key features near Barrow, Alaska.

storm wind

Delft3D is a fully-coupled suite of models:FLOW, WAVE, SED, MOR, WAQ & PART

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.

Preliminary DEM with Bathymetry for Barrow, AK and Vicinity.

Example of an Orthogonal Computational Gridfor the Flow and Sediment Transport Modeling

Other Examples of Computational Grids

Hong Kong North Sea

Summary of Big Storms Near Barrow

October 3-5, 1963Ice-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.)

August 10, 2000Ice-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.

NOTE:The prevailing winddirection for Barrowis from E to ENE,with typical speedsof 11 to 12 mph.Normal daily tideis 6 inches.

Observed Reduction in Sea-IceExtent from 1979 to 1995

A reduction in sea-ice extent is expected to increase thelikelihood of coastal erosion and damage from large storms.Even partial coverage inhibits the formation of large waves.

Base station (on top of the old theatre in the NARL complex) used for the differential GPS measurements.

(William Manley &Mark Dyurgerov, 2001)

Using differential GPS to measure coastline position.(Credit: William Manley & Mark Dyurgerov)

Annotated Aerial Photo of Barrow, Alaska

Coastal bluffs southwest of Barrow.

Differential GPS was alsoused to measure the currentposition of the bluffs andto collect data for highresolution DEMs of somebluff faces.

(Credit: William Manley &Mark Dyurgerov, INSTAAR)

Establishment of 63 Ground Control Points

Conclusions

Although we are still in the early stages of this work, itappears that Delft3D and associated modules will allow usto model sediment transport along the coast of Barrow, AKin response to large storms such as those observed inOctober of 1963 and August of 2000.

This will allow us to quantify the cumulative effect ofseveral such storms, and to explore various mitigationscenarios such as dredging and beach nourishment.

The Main Modules of Delft CHESS

UNIBEST: Longshore & cross-shore sediment transport model for predicting shoreline evolution.