Jul 13

Conference | 36th IAHR World Congress

StaticvsDynamicM.V. Bilskie, S.C. Hagen & J. Irish, “Development of future tropical cyclone 100-year floodplains in a changing climate” 36th IAHR World Congress, Delft-The Hague, The Netherlands, June 28 – July 3, 2015.

Permanent link to this article: http://www.mattbilskie.com/conference-36th-iahr-world-congress/

May 08

Publication | The dynamic effects of sea level rise on low gradient coastal landscapes: a review

SLR_EnchroachD.L. Passeri, S.C. Hagen, S.C. Medeiros, M.V. Bilskie, K. Alizad, D. Wang (2015). “The dynamic effects of sea level rise on low gradient coastal landscapes: a review.” AGU Earth’s Future, doi:10.1002/2015EF000298

Abstract: Coastal responses to sea level rise (SLR) include inundation of wetlands, increased shoreline erosion, and increased flooding during storm events. Hydrodynamic parameters such as tidal ranges, tidal prisms, tidal asymmetries, increased flooding depths and inundation extents during storm events respond non-additively to SLR. Coastal morphology continually adapts towards equilibrium as sea levels rise, inducing changes in the landscape. Marshes may struggle to keep pace with SLR and rely on sediment accumulation and the availability of suitable uplands for migration. Whether hydrodynamic, morphologic or ecologic, the impacts of SLR are interrelated. To plan for changes under future sea levels, coastal managers need information and data regarding the potential effects of SLR to make informed decisions for managing human and natural communities. This review examines previous studies that have accounted for the dynamic, nonlinear responses of hydrodynamics, coastal morphology and marsh ecology to SLR by implementing more complex approaches rather than the simplistic “bathtub” approach. These studies provide an improved understanding of the dynamic effects of SLR on coastal environments and contribute to an overall paradigm shift in how coastal scientists and engineers approach modeling the effects of SLR, transitioning away from implementing the “bathtub” approach. However, it is recommended that future studies implement a synergetic approach that integrates the dynamic interactions between physical and ecological environments to better predict the impacts of SLR on coastal systems.

Permanent link to this article: http://www.mattbilskie.com/publication-the-dynamic-effects-of-sea-level-rise-on-low-gradient-coastal-landscapes-a-review/

Apr 16

2015 LA ASCE Conference| Storm surge modeling in the northern Gulf of Mexico

M.V. Bilskie, S.C. Hagen, D.L. Passeri, K. Alizad, S.C. Medeiros, D. Coggin, J.L. Irish, N. Plant, A. Cox, C. Kaiser “Tide, wind-wave & hurricane storm surge modelling in the northern Gulf of Mexico under climate change.” 2015 ASCE Louisiana Section Spring Conference, Baton Rouge, LA, April 16-17, 2015.

Permanent link to this article: http://www.mattbilskie.com/2015-la-asce-conference-storm-surge-modeling-in-the-northern-gulf-of-mexico/

Apr 02

2015 ADCIRC User’s Group Meeting| Storm surge modeling in the northern Gulf of Mexico

M.V. Bilskie, S.C. Hagen, D.L. Passeri, K. Alizad, S.C. Medeiros, D. Coggin, J.L. Irish, N. Plant, A. Cox, “Tide, wind-wave & hurricane storm surge modelling in the northern Gulf of Mexico | climate change.” 2015 ADCIRC User’s Group Meeting, Silver Spring, MD, March 30-31, 2015.

Permanent link to this article: http://www.mattbilskie.com/2015-adcirc-users-group-meeting-storm-surge-modeling-in-the-northern-gulf-of-mexico/

Feb 23

Publication | Development and uncertainty quantification of hurricane surge response functions for hazard assessment in coastal bays

Taylor-2015-CoverPhoto

N.R. Taylor, J.L. Irish, I.E. Udoh, M.V. Bilskie, S.C. Hagen (2015). “Development and uncertainty quantification of hurricane storm surge response functions for hazard assessment in coastal bays.” Natural Hazards, doi:10.1007/s11069-015-1646-5

Abstract: Reliable and robust methods of extreme value-based hurricane surge prediction,
such as the joint probability method (JPM), are critical in the coastal engineering
profession. The JPM has become the preferred surge hazard assessment method in the
USA; however, it has a high computational cost: One location can require hundreds of
simulated storms and more than ten thousand computational hours to complete. Optimal
sampling methods that use physics-based surge response functions (SRFs) can reduce the
required number of simulations. This study extends the development of SRFs to bay
interior locations at Panama City, Florida. Mean SRF root-mean-square errors for open
coast and bay interior locations were 0.34 and 0.37 m, respectively, comparable with
ADCIRC errors. Average uncertainty increases from open coast, and bay SRFs were 10
and 12 %, respectively. Long-term climate trends, such as rising sea levels, introduce
nonstationarity into the simulated and historical surge datasets. A common approach to
estimating total flood elevations is to take the sum of projected sea-level rise (SLR) and
present day surge (static approach); however, this does not account for dynamic SLR
effects on surge generation. This study demonstrates that SLR has a significant dynamic
effect on surge in the Panama City area, and that total flood elevations, with respect to
changes in SLR, are poorly characterized as static increases. A simple adjustment relating
total flood elevation to present day conditions is proposed. Uncertainty contributions from
these SLR adjustments are shown to be reasonable for surge hazard assessments.

Permanent link to this article: http://www.mattbilskie.com/development-and-uncertainty-quantification-of-hurricane-surge-response-functions-for-hazard-assessment-in-coastal-bays/

Dec 20

2014 AGU Fall Meeting | Assessment of coastal flood risk in a changing climate along the northern Gulf of Mexico

FWJ_159stormsM.V. Bilskie, S.C. Hagen, D.L. Passeri, K. Alizad, “Assessment of coastal flood risk in a changing climate along the northern Gulf of Mexico.” 2014 AGU Fall Meeting. San Fransisco, CA, December 15-19, 2014.

Abstract: Coastal regions around the world are susceptible to a variety of natural disasters causing extreme inundation. It is anticipated that the vulnerability of coastal cities will increase due to the effects of climate change, and in particular sea level rise (SLR). We have developed a novel framework to construct a physics-based storm surge model that includes projections of coastal floodplain dynamics under climate change scenarios. Numerous experiments were conducted and it was concluded that a number of influencing factors, other than SLR, should be included in future assessments of coastal flooding under climate change; e.g., shoreline changes, barrier island morphology, salt marsh migration, and population dynamics. These factors can significantly affect the path, pattern, and magnitude of flooding depths and inundation along the coastline (Bilskie et al., 2014; Passeri et al., 2014).

Using these factors, a storm surge model of the northern Gulf of Mexico (NGOM) representing present day conditions is modified to characterize the future outlook of the landscape. This adapted model is then used to assess flood risk in terms of the 100-year floodplain surface under SLR scenarios. A suite of hundreds of synthetic storms, derived by JPM-OS (Joint Probability Method – Optimum Sampling), are filtered to obtain the storms necessary to represent the statistically determined 100-year floodplain. The NGOM storm surge model is applied to simulate the synthetic storms and determine, for each storm, the flooding surface and depth, for four SLR scenarios for the year 2100 as prescribed by Parris et al. (2012). The collection of results facilitate the estimation of water surface elevation vs. frequency curves across the floodplain and the statistically defined 100-year floodplain is extracted. This novel method to assess coastal flooding under climate change can be performed across any coastal region worldwide, and results provide awareness of regions vulnerable to extreme flooding in the future.

Permanent link to this article: http://www.mattbilskie.com/agu14-assessment-of-coastal-flood-risk/

Dec 10

Multiple-thread gzip

I was recently backing up some very large datasets and became impatient with the typical time it takes from creating *.tar.gz archives. During one backup session I started searching for a possible method to utilize multiple threads. I came across pigz, which is basically a parallel implementation of gzip. I came across an interesting thread on linuxquestions.org discussing how to implement pigz with tar, instead of gzip with tar (http://bit.ly/1zPFbHS).

Here was one of the recommended solutions by user dru8274.
To compress:
tar -I pigz -cf out.tgz in/

To extract:
tar -I pigz -xf out.tgz in/

I performed a non-scientific benchmark test on a 5.0 GB directory with an 4-core (8-thread) Intel Xeon 3.70 3.7 Ghz. The directory contains a good mix of MS documents, ASCII text files and images. The typical tar -xzf command took 6 minutes, while using pigz instead of gzip resulted in a wall time of 3 minutes. This is a significant time saver!

Permanent link to this article: http://www.mattbilskie.com/multiple-thread-gzip/

Oct 29

High performance computing of oceanic and nearshore hydrodynamic processes

NGOM_512DecompInvited Presentation

M.V. Bilskie, S.C. Hagen, D.L. Passeri, K. Alizad, S.C. Medeiros, “High performance computing of oceanic and nearshore hydrodynamic processes.” HPC User Group of Orlando Meeting, October 28, 2014.

Permanent link to this article: http://www.mattbilskie.com/high-performance-computing-of-oceanic-and-nearshore-hydrodynamic-processes/

Oct 13

Modeling hurricane waves and storm surge under climate change in the northern Gulf of Mexico

 

Hurricane Dennis water surface elevation at landfall.

Hurricane Dennis water surface elevation at landfall.

Invited Presentation

M.V. Bilskie, S.C. Hagen, D.L. Passeri, K. Alizad, S.C. Medeiros,“Modeling hurricane waves and storm surge
under climate change in the northern Gulf of Mexico.” Louisiana State University, October 10, 2014.

The vulnerability of the built and natural environment in coastal regions will increase due to the effects of global climate change in general, and sea level rise (SLR) in particular. Climate change perturbs the natural state of the environment and can create short- or long-term changes in sea level, shoreline position and profile, barrier islands, intertidal salt marsh productivity, and human-induced change such as population dynamics. The goal is to examine the vulnerability of coastal flooding in the northern Gulf of Mexico from hurricane waves and storm surge under various climate change scenarios. A large-domain, high-resolution, wave and storm surge model that spans the Florida panhandle to the western Mississippi coast was developed and applied to recreate historical events such as Hurricane Dennis, Ivan, Katrina, and Isaac. The storm surge model is modified to include projected changes to shoreline positions and profiles, coastal dune elevations, salt marsh migration, and changes in land use / land cover. Numerous simulations are carried out and are driven by a comprehensive set of synthetic wind fields that result in a large population of flooding surfaces and are statistically analyzed to project a representation of the 100-year floodplain for each SLR scenario. Comparisons between 100-year floodplain maps under present and future SLR scenarios will be used to assess the vulnerability of the northern Gulf of Mexico to coastal storm surge flooding.

Permanent link to this article: http://www.mattbilskie.com/invited-presentation-modeling-hurricane-waves-and-storm-surge-under-climate-change-in-the-northern-gulf-of-mexico/

Sep 09

Publication | On the significance of incorporating shoreline changes for evaluating coastal hydrodynamics under sea level rise scenarios

Passeri-Fig1

D.L. Passeri, S.C. Hagen, M.V. Bilskie, S.C. Medeiros,  (2014). “On the significance of incorporating shoreline changes for evaluating coastal hydrodynamics under sea level rise scenarios.” Natural Hazards, doi:10.1007/s11069-014-1386-y.

Abstract: The influence of including the dynamic effects of future shoreline changes associated with sea level rise into hydrodynamic modeling is evaluated for the coast of the Northern Gulf of Mexico from Mobile Bay, AL to St. Andrew Bay, FL. A two-dimensional, depth-integrated hydrodynamic model forced by astronomic tides and hurricane winds and pressures representative of Hurricanes Ivan (2004), Dennis (2005) and Katrina (2005) is used to simulate present conditions, 2050 projected sea level (0.46 m rise) with present-day shorelines, and 2050 sea level with projected 2050 shorelines. The 2050 shoreline and nearshore morphology are projected using Coastal Vulnerability Index shoreline change rates to determine the position of the new Gulf and bay shorelines, while the active beach profile is shifted horizontally according to the amount of erosion or accretion, and vertically to keep pace with rising seas. Hydrodynamic model results show that taking a dynamic approach to modeling sea level rise (as opposed to a static, or ‘‘bathtub’’ approach) increases tidal ranges and tidal prisms within the bay systems. Incorporating the projected shoreline changes does not alter tidal ranges, but some bays experience changes in tidal prisms depending on whether the planform area of the bay increases or decreases with the projected erosion or accretion. Barrier islands with projected erosion are vulnerable to increased overtopping from storm surge inundation, which impels more water into the back-bays and increases the inland inundation extent and magnitude. Inundation along barrier islands with projected accretion remains relatively the same as inundation under present-day shorelines, which prevents additional overtopping and limits more water from entering back-bays. Results demonstrate that although modeling sea level rise as a dynamic process is necessary, the incorporation of shoreline changes has variable impacts when evaluating future hydrodynamics and the response of the coastal system to sea level rise.

Permanent link to this article: http://www.mattbilskie.com/on-the-significance-of-incorporating-shoreline-changes-for-evaluating-coastal-hydrodynamics-under-sea-level-rise-scenario/

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