Geomorphic Versus Climatic Drivers of Changing Coastal Flood Risk

PI Philip Orton, Stevens Institute of Technology

PI Thomas Wahl, University of Central Florida 

PI James Booth, City University of New York

PI Stefan Talke, Portland State University / California Polytechnic State University

Funding agency/program:  National Science Foundation, Prediction of and Resilience to Extreme Events (PREEVENTS)

Project Period:  June 2019 to May 2024 (completed)

Below are (a) a summary, (b) list of peer-reviewed publications and (c) datasets, codes and tools.

SUMMARY

In this collaborative research between four universities we investigated how and why changing flood risk in estuaries is influenced by direct, human activities but also natural variability and climate trends. The increased flood hazard caused by sea level rise and U.S. coastal population growth are well known. Less studied, however, is how flooding in estuaries is changing due to geomorphic changes such as dredging and both natural and climatic variability.  The characteristics of storm surge and coastal flooding depend on both far-field forcing (meteorological, oceanographic) and on local characteristics (estuary bathymetry, floodplain land cover).  As a result, changes to any of these factors may greatly influence flood hazard.  In many locations, the local changes are huge: since the 19th century, estuary channels have typically been deepened and widened by a factor of two or three, harbor entrances have been deepened and streamlined, and a large proportion of wetlands have been lost to landfill development.  Our research shows that such geomorphic changes, which can be referred to as estuary urbanization,  increase flood risk by reducing natural resistance to storm surge and tides.  Similarly, sea level rise, natural (astronomically-forced) variations in tides, and variable storm characteristics such as storm track, speed, or size also alter flood risk.  

Our results are helping to show that estuary urbanization can have a major impact on flood hazards, worsening both storm surge and high-tide flooding.  Increases in tidal amplitudes are exacerbating nuisance (“high tide”) flooding at nearly half of the long-term measurement sites evaluated (18 of 40 NOAA gauges).  The number of nuisance floods was 27% higher in 2019 at those 18 locations than it would have been without tidal amplitude increases.  Our evidence and computer modeling show that any hurricane storm surge affecting parts of New York City, Jacksonville, Wilmington, Philadelphia and South Florida, among other locations, will likely produce higher water levels due to estuary urbanization, potentially causing more damage in unprotected regions.  

Our research is also helping to reveal and contrast the mechanisms by which climate and weather variability and geomorphic changes alter flood risk. Increases in storm surge (for the same meteorological forcing) are often strongest in urbanized estuaries that previously had natural features that reduced surges (e.g., the Saint Johns Estuary).  Idealized modeling of storm surge shows that the amount of change due to channel deepening also depends on tide-surge non-linear frictional effects, the time scale of the surge (fast or slow), the frequency of the major tide forcing, and the magnitude or river flow.  Large increases in tides and storm surge water levels are also often observed at estuary boundaries, both due to long-wave reflection effects but also sometimes resonance.  Finally, our research shows that natural variations in tides, for example over the 18.6 year nodal cycle and the 8.85 year cycle of lunar perigee, influence the risk of major floods in about 70% of the 551 gauges evaluated. In Boston, the area of the 100 year floodplain varies by about 45% over a 18.6 year cycle (under current sea-level conditions).   

We also developed methods for attribution of flooding to climate change and geomorphic change.  The roles of geomorphic change and climate change on flooding were contrasted for New York City’s heavily urbanized Jamaica Bay, revealing that geomorphic change has had a similar influence as climate change driven sea level rise.  For most coastal sites, however, sea level rise has a larger impact than geomorphic change.  

This project also provides a new understanding of how weather variability can determine flood characteristics.  For example, research showed that the interaction of storms and blocking anticyclones can lead to persistent storm surge events for the Northeastern US.  For tropical cyclone events along the East Coast occurring over the last half century, the project provided a sensitivity analysis relating storm surge events to storm characteristics such as storm strength, forward speed and approach angle.  It also provided benchmarks on storm surge probabilities. Work examining the spatial footprints of storms showed regions in which flood risk is coherent.  In the future, all these efforts can help improve models, and provide avenues for using less spatially and temporally complete historical data to improve understanding of past climate change. 

The project leveraged interactions with several governmental entities to broaden the reach of our findings – The New York City Office of Restoration and Resilience (via the NYC Panel on Climate Change), the US Geological Survey and the US Army Corps of Engineers.  It also provided significant support for three early career principal investigators, 5 postdoctoral research associates, 5 PhD students, 6 MS students, and 3 undergraduates and 2 high school students, with several of these coming from groups that are underrepresented in academic science. 

PROJECT PUBLICATIONS

Baranes, H. E. and Woodruff, J. D. and Talke, S. A. and Kopp, R. E. and Ray, R. D. and DeConto, R. M. “Tidally Driven Interannual Variation in Extreme Sea Level Frequencies in the Gulf of Maine” Journal of Geophysical Research: Oceans , v.125 , 2020 https://doi.org/10.1029/2020JC016291 

Booth, James F. and Narinesingh, Veeshan and Towey, Katherine L. and Jeyaratnam, Jeyavinoth “Storm Surge, Blocking, and Cyclones: A Compound Hazards Analysis for the Northeast United States” Journal of Applied Meteorology and Climatology , 2021 https://doi.org/10.1175/JAMC-D-21-0062.1

Chen, Ziyu and Orton, Philip and Wahl, Thomas “Storm Surge Barrier Protection in an Era of Accelerating Sea-Level Rise: Quantifying Closure Frequency, Duration and Trapped River Flooding” Journal of Marine Science and Engineering , v.8 , 2020 https://doi.org/10.3390/jmse8090725

Calafat, Francisco M. and Wahl, Thomas and Tadesse, Michael Getachew and Sparrow, Sarah N. “Trends in Europe storm surge extremes match the rate of sea-level rise” Nature , v.603 , 2022 https://doi.org/10.1038/s41586-022-04426-5 

De Leo, F. and Talke, S. A. and Orton, P. M. and Wahl, T. “The Effect of Harbor Developments on Future High-Tide Flooding in Miami, Florida” Journal of Geophysical Research: Oceans , v.127 , 2022 https://doi.org/10.1029/2022JC018496

Devlin, Adam T. and Jay, David A. and Talke, Stefan A. and Pan, Jiayi “Global water level variability observed after the Hunga Tonga-Hunga Ha’apai volcanic tsunami of 2022” Ocean Science , v.19 , 2023 https://doi.org/10.5194/os-19-517-2023 

Enriquez, Alejandra R and Wahl, Thomas and Talke, Stefan A and Orton, Philip M and Booth, James F and Agulles, Miguel and Santamaria-Aguilar, Sara “MatFlood: An efficient algorithm for mapping flood extent and depth” Environmental Modelling & Software , v.169, 2023 https://doi.org/10.1016/j.envsoft.2023.105829 

Enríquez, Alejandra R. and Wahl, Thomas and Baranes, Hannah E. and Talke, Stefan A. and Orton, Philip M. and Booth, James F. and Haigh, Ivan D. “Predictable Changes in Extreme Sea Levels and Coastal Flood Risk Due To Long?Term Tidal Cycles” Journal of Geophysical Research: Oceans , v.127 , 2022 https://doi.org/10.1029/2021JC018157

Enríquez, Alejandra R. and Wahl, Thomas and Marcos, Marta and Haigh, Ivan D. “Spatial Footprints of Storm Surges Along the Global Coastlines” Journal of Geophysical Research: Oceans , v.125 , 2020 https://doi.org/10.1029/2020JC016367

Fang, Jiayi and Wahl, Thomas and Zhang, Qiang and Muis, Sanne and Hu, Pan and Fang, Jian and Du, Shiqiang and Dou, Tingfeng and Shi, Peijun “Extreme sea levels along coastal China: uncertainties and implications” Stochastic Environmental Research and Risk Assessment , v.35 , 2021 https://doi.org/10.1007/s00477-020-01964-0

Familkhalili, Ramin and Talke, Stefan A. and Jay, David A. “Compound flooding in convergent estuaries: insights from an analytical model” Ocean Science , v.18 , 2022 https://doi.org/10.5194/os-18-1203-2022

Familkhalili, R. and Talke, S. A. and Jay, D. A. “Tide-Storm Surge Interactions in Highly Altered Estuaries: How Channel Deepening Increases Surge Vulnerability” Journal of Geophysical Research: Oceans , v.125 , 2020 https://doi.org/10.1029/2019JC015286 

Hague, Ben S. and Grayson, Rodger B. and Talke, Stefan A. and Black, Mitchell T. and Jakob, Dörte “The effect of tidal range and mean sea-level changes on coastal flood hazards at Lakes Entrance, south-east Australia” Journal of Southern Hemisphere Earth Systems Science , 2023 https://doi.org/10.1071/ES22036 

Haigh, Ivan D. and Marcos, Marta and Talke, Stefan A. and Woodworth, Philip L. and Hunter, John R. and Hague, Ben S. and Arns, Arne and Bradshaw, Elizabeth and Thompson, Philip “GESLA Version 3: A major update to the global higher?frequency sea?level dataset” Geoscience Data Journal , 2022 https://doi.org/10.1002/gdj3.174 

Hudson, Austin and Jay, David and Talke, Stefan “The Bed Stress Minimum in Tidal Rivers” Estuaries and Coasts , v.46 , 2023 https://doi.org/10.1007/s12237-022-01156-9

Latapy, Alexa and Ferret, Yann and Testut, Laurent and Talke, Stefan and Aarup, Thorkild and Pons, Frederic and Jan, Gwenaele and Bradshaw, Elizabeth and Pouvreau, Nicolas “Data rescue process in the context of sea level reconstructions: An overview of the methodology, lessons learned, up?to?date best practices and recommendations” Geoscience Data Journal , 2022 https://doi.org/10.1002/gdj3.179

Li, Linjiang and Zhu, Jianrong and Pareja-Roman, L. Fernando “Calculating salinity variance fluxes using isohaline coordinates” Estuarine, Coastal and Shelf Science , v.254 , 2021 https://doi.org/10.1016/j.ecss.2021.107311

Li, Sida and Wahl, Thomas and Talke, Stefan A. and Jay, David A. and Orton, Philip M. and Liang, Xinghui and Wang, Guocheng and Liu, Lintao “Evolving tides aggravate nuisance flooding along the U.S. coastline” Science Advances , v.7 , 2021 https://doi.org/10.1126/sciadv.abe2412 

Li, S. and Wahl, T. and Fang, J. and Liu, L. and Jiang, T. “High-Tide Flooding Along the China Coastline: Past and Future” Earth’s Future , v.11 , 2023 https://doi.org/10.1029/2022EF003225

Li, Linjiang and Zhu, Jianrong and Chant, Robert J. and Wang, Chuning and Pareja?Roman, L. Fernando “Effect of Dikes on Saltwater Intrusion Under Various Wind Conditions in the Changjiang Estuary” Journal of Geophysical Research: Oceans , v.125 , 2020 10.1029/2019JC015685 

Nicholls, Robert J. and Beaven, Richard P. and Stringfellow, Anne and Monfort, Daniel and Le Cozannet, Gonéri and Wahl, Thomas and Gebert, Julia and Wadey, Matthew and Arns, Arne and Spencer, Kate L. and Reinhart, Debra and Heimovaara, Timo and Santos, Ví “Coastal Landfills and Rising Sea Levels: A Challenge for the 21st Century” Frontiers in Marine Science , v.8 , 2021 https://doi.org/10.3389/fmars.2021.710342

Nicholls, Robert J. and Hanson, Susan E. and Lowe, Jason A. and Slangen, Aimée B. A. and Wahl, Thomas and Hinkel, Jochen and Long, Antony J. “Integrating new sea?level scenarios into coastal risk and adaptation assessments: An ongoing process” WIREs Climate Change , v.12 , 2021 https://doi.org/10.1002/wcc.706

Orton, Philip M. and Sanderson, Eric W. and Talke, Stefan A. and Giampieri, Mario and MacManus, Kytt “Storm tide amplification and habitat changes due to urbanization of a lagoonal estuary” Natural Hazards and Earth System Sciences , v.20 , 2020 https://doi.org/10.1029/2022JC018777

Pareja-Roman, L. Fernando and Orton, P. M. and Talke, S. A. “Effect of Estuary Urbanization on Tidal Dynamics and High Tide Flooding in a Coastal Lagoon” Journal of Geophysical Research: Oceans , v.128 , 2023 https://doi.org/10.1029/2022JC018777

Strauss, Benjamin H. and Orton, Philip M. and Bittermann, Klaus and Buchanan, Maya K. and Gilford, Daniel M. and Kopp, Robert E. and Kulp, Scott and Massey, Chris and Moel, Hans de and Vinogradov, Sergey “Economic damages from Hurricane Sandy attributable to sea level rise caused by anthropogenic climate change” Nature Communications , v.12 , 2021 https://doi.org/10.1038/s41467-021-22838-1

Tadesse, Michael Getachew and Wahl, Thomas and Rashid, Md Mamunur and Dangendorf, Sönke and Rodríguez-Enríquez, Alejandra and Talke, Stefan Andreas “Long-term trends in storm surge climate derived from an ensemble of global surge reconstructions” Scientific Reports , v.12 , 2022 https://doi.org/10.1038/s41598-022-17099-x 

Talke, S. A. and Familkhalili, R. and Jay, D. A. “The Influence of Channel Deepening on Tides, River Discharge Effects, and Storm Surge” Journal of Geophysical Research: Oceans , v.126 , 2021 https://doi.org/10.1029/2020JC016328 

Towey, Katherine L. and Booth, James F. and Rodriguez Enriquez, Alejandra and Wahl, Thomas “Tropical cyclone storm surge probabilities for the east coast of the United States: a cyclone-based perspective” Natural Hazards and Earth System Sciences , v.22 , 2022 https://doi.org/10.5194/nhess-22-1287-2022 

Treu, Simon and Muis, Sanne and Dangendorf, Sönke and Wahl, Thomas and Oelsmann, Julius and Heinicke, Stefanie and Frieler, Katja and Mengel, Matthias “Reconstruction of hourly coastal water levels and counterfactuals without sea level rise for impact attribution” Earth System Science Data , v.16 , 2024 https://doi.org/10.5194/essd-16-1121-2024

Zhang, Fanglin and Orton, Philip M. “Importance of Neighborhood Aspect Ratio and Storm Climate to Adaptation Efforts to Reduce Coastal Flood Mortality” Frontiers in Built Environment , v.7 , 2022 https://doi.org/10.3389/fbuil.2021.769161

PROJECT DATASETS, CODES and TOOLS

• The MatFlood package developed in Enriquez et al. (2023) is available via Zenodo: https://doi.org/10.5281/zenodo.7682917 
• The BAYEX Model used in Calafat et al. (2022) is available via Zenodo: https://zenodo.org/records/5035438 
• The qn-SSJPM code from Baranes et al. (2020) that was used in Enriquez et al. (2022) is available via Zenodo: https://zenodo.org/records/3898657 
• Codes used in Treu et al. (2024) are available via Zenodo: https://zenodo.org/records/10354898 
• Code that was used to develop the GSSR database that was analyzed in Tadesse et al. (2022) is available via GitHub: https://github.com/CoRE-Lab-UCF/GSSR The GSSR database itself is available via: https://gssr.info/ 
• Code used in Li et al. (2023) is available via GitHub: https://github.com/CoRE-Lab-UCF/Sea-level-components-and-contribution 
• Archival hourly water level data developed for and used in Talke et al. (2020), Talke et al. (2021) and de Leo et al. (2022) is available in the GESLA-3 data set described in Haigh et al., (2023) and available here: https://gesla787883612.wordpress.com/
• Additional archival water level, bathymetry, numerical modeling, and water temperature data developed for Talke et al. (2020), Helaire et al., (2020), Talke et al. (2021) and Talke et al. (2023) is available at Portland State University data repositories:  https://pdxscholar.library.pdx.edu/cengin_data/3/ and https://pdxscholar.library.pdx.edu/cengin_data/4/ and https://pdxscholar.library.pdx.edu/cengin_data/5/ and https://pdxscholar.library.pdx.edu/cengin_data/6/  
• Future projections of flooding and historical Biscayne Bay bathymetry from De Leo et al. (2022) are available at https://doi.org/10.5281/zenodo.6551549.
• The regression model and quality assurance methodology used in Baranes et al. (2023) is available at: https://www.hydroshare.org/resource/60a77d2b6df446d8bb4390cd94712459/ and https://www.hydroshare.org/resource/47505deb95cc4df08a9de4d1e1641f71
• Archival water level data from the 1980s-2007 were acquired as part of the PREEVENTS project from the US Geological Survey for Dykstra et al. (2024).  These data have now been made available at https://waterdata.usgs.gov/ 
• Data on Jamaica Bay’s historical landscape change (1870s versus present-day), tides and high-tide flooding are published and available at https://doi.org/10.5281/zenodo.4776403.
• The atmospheric blocks used in Booth et al. (2021) are available on the Harvard Dataverse: https://doi.org/10.7910/DVN/Z0SYUG
• The detrended storm surge data used in Booth et al. (2021) Towey et al. (2022) are available on the Harvard Dataverse: https://doi.org/10.7910/DVN/NGTGXY
• The extratropical cyclone tracks detected and used in Booth et al. (2021) are available on the Harvard Dataverse: https://doi.org/10.7910/DVN/YC3STT
• The code for tracking extratropical cyclones that was used in Booth et al. (2021) is available via GitHub: https://github.com/jfbooth/MIKE_BAUERS_MCMSV4

References and links to open-source and other data sets used in the project can be found in data availability statements in the linked publications, and in manuscript supplements.