Many coastal cities around the world are at risk of increased flooding due to sea level rise (SLR), so here a simple flood prediction method is demonstrated for one city at risk, Norfolk, VA, on the U.S. East Coast. The probability of future flooding is estimated by extending observed hourly water level for 1927–2021 into hourly estimates until 2100. Unlike most other flood prediction methods, the approach here does not use any predetermined probability distribution function of extreme events, and instead a random sampling of past data represents tides and storm surges. The probability of flooding for 3 different flood levels and 3 different SLR projections are calculated, and the results are consistent with more sophisticated methods. Under intermediate-low SLR projection an empirical formula is found to estimate the lower bound of flooding time, showing that water level that exceeds the high tide (Mean Higher High Water, MHHW) occurred ∼0.3% of the time in the 1960s, increased to ∼6% in 2021, and projected to occur 100% of the time by ∼2080. Under intermediate SLR projection, 1000 simulations of the probability of maximum annual water level were conducted, showing that storm surges may reach ∼2 m over MHHW by 2050 and ∼3 m over MHHW by 2100; in comparison, storm surges in Norfolk over the past 90 years reached 1.6 m only once. The method derived here could be adopted to other locations and help planning mitigations and adaptation strategies for cities at risk.
© 2022 The Authors. Earth's Future published by Wiley Periodicals LLC on behalf of American Geophysical Union. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Article states: "The hourly tide gauge sea level record for Norfolk is available from NOAA (https://tidesandcurrents.noaa.gov/waterlevels.html?id=8638610) and the sea level rise projections are available from USACE (https://cwbi-app.sec.usace.army.mil/rccslc/slcc_calc.html). Analysis and graphic tools are based on standard Matlab codes (https://www.mathworks.com/products/matlab.html)."
Original Publication Citation
Ezer, T. (2022). A demonstration of a simple methodology of flood prediction for a coastal city under threat of sea level rise: The case of Norfolk, VA, USA. Earth's Future, 10(9), Article e2022EF002786. https://doi.org/10.1029/2022EF002786
Ezer, Tal, "A Demonstration of a Simple Methodology of Flood Prediction for a Coastal City Under Threat of Sea Level Rise: The Case of Norfolk, VA, USA" (2022). CCPO Publications. 372.