Deterministic, Dynamic Model Forecasts of Storm‑Driven Coastal Erosion

The U.S. Atlantic and Gulf of Mexico coasts are vulnerable to storms, which can cause significant erosion of beaches and dunes that protect coastal communities. Real-time forecasts of storm-driven erosion are useful for decision support, but they are limited due to demands for computational resources and uncertainties in dynamic coastal systems and storm forcings. Current methods for coastal change forecasts are based on empirical calculations for wave run-up and conceptual models for erosion, which do not represent sediment transport and morphological change during the storm. However, with continued advancements in high-resolution geospatial data and computational efficiencies, there is an opportunity to apply morphodynamic models for forecasts of beach and dune erosion as a storm approaches the coast. In this study, we implement a forecast system based on a deterministic, dynamic model. The morphodynamic model is initialized with digital elevation models of the most up-to-date conditions and forced with hydrodynamics from wave and circulation model forecasts, and its predictions are categorized based on impact to the primary dune, defined in this study as the first ridge of sand landward of the beach. Results are compared spatially to the observed post-storm topography using changes to dune crest elevations and volumes, and temporally to the predicted total water level at the forecasted moment of dune impact.

JF Gorski, JC Dietrich, DL Passeri, RC Mickey, RA Luettich Jr (2025). “Deterministic, Dynamic Model Forecasts of Storm‑Driven Coastal Erosion.” Natural Hazards, 121(5), 6257-6283, DOI: 10.1007/s11069-024-07012-2.

Casey is Alumni Distinguished Undergraduate Professor

Casey Dietrich was selected as an Alumni Distinguished Undergraduate Professor. It is one of the most prestigious undergraduate teaching awards at NC State, and winners retain the title for as long as they remain a member of the NC State faculty. Finalists are nominated by their colleges, and then winners are selected at the university level. During 2024-2025, the award was given to 6 instructors, or less than 1 per 400 faculty members.

Casey received the award from Dr. Helen Chen, Senior Vice Provost for Instructional Programs, at the University Teaching Awards Luncheon and Ceremony.

Posters: EWC Symposium 2025

NK Arrigo, JC Dietrich, TC Massey. “Spatial controls and efficiency gains within a spectral wave model.Environmental, Water Resources, and Coastal Engineering Graduate Research Symposium, North Carolina State University, 21 Mar 2025.

Spatial controls and efficiency gains within a spectral wave model.

JT Voight, JS Knowles, JC Dietrich. “Analyzing Dune Maintenance effects on Storm Surge at Tyndall Air Force Base.Environmental, Water Resources, and Coastal Engineering Graduate Research Symposium, North Carolina State University, 21 Mar 2025.

Analyzing Dune Maintenance effects on Storm Surge at Tyndall Air Force Base.

NM Pieu, JC Dietrich. “Prediction of Dune Erosion and Inlet Formation during Hurricanes Helene and Milton.Environmental, Water Resources, and Coastal Engineering Graduate Research Symposium, North Carolina State University, 21 Mar 2025.

Prediction of Dune Erosion and Inlet Formation during Hurricanes Helene and Milton.

ME McKenna, JC Dietrich, TA Cuevas López. “Neural Network Predictions of Flood Maps.Environmental, Water Resources, and Coastal Engineering Graduate Research Symposium, North Carolina State University, 21 Mar 2025.

Neural Network Predictions of Flood Maps

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Sensitivity of Water Level and Flood Area Prediction to Hurricane Characteristics and Climate Change Impacts

The combined impact of hurricanes and climate change can affect the total water level leading to severe impacts on coastal zones such as flooding. Accurate prediction and evaluation of water levels are essential for predicting the impact on military readiness and resilience for coastal facilities. This study uses D-Flow Flexible Mesh to evaluate the sensitivity of water level and flood area prediction to the impact of climate change and hurricane activity with application to the Naval Station Norfolk, Virginia, USA.

The water level (tide and surge) was simulated and the potential flooding resulting from historical hurricanes (Irene and Isabel) in Norfolk, VA was evaluated. The model was forced using the parametric Holland Model and various perturbations in the hurricane characteristics were evaluated. In addition, projected relative sea level rise up to the year 2150 was investigated.

D-Flow can accurately simulate the water level with an average correlation coefficient and root-mean-square-error of 0.974 and 0.17 m, respectively. Water level prediction showed high sensitivity to climate change impacts and inaccuracies in hurricane track and lower sensitivity to changes in hurricane central pressure and radius of maximum wind. A mesh resolution that reflects accurate topographical depiction is required to estimate the flood area accurately. Willoughby Spit (a narrow peninsula north of the naval base extending into Chesapeake Bay) was the most susceptible area to flooding. Significant parts of the base were found to be vulnerable to flooding under the considered scenarios, with flood areas ranging from 0.28 km2 to 5.94 km2 (1.3%–43% of the base area), with the largest predicted flooding for the sea level rise and wind speed scenarios. The insights of the sensitivity of flood predictions to various factors could enable targeted adaptation measures and resource allocation, for enhanced resilience and sustainable development in vulnerable coastal areas.

A Elkut, F Shi, JS Knowles, JC Dietrich, JA Puleo (2025). “Sensitivity of Water Level and Flood Area Prediction to Hurricane Characteristics and Climate Change Impacts.” Ocean and Coastal Management, 262, 107573, DOI: 10.1016/j.ocecoaman.2025.107573.

News: Erosion Forecast Framework

2025/01/22 – NCSU Civil, Construction, and Environmental Engineering
New technology forecasts beach and dune erosion before hurricanes strike

ncsu-engr

“Physics-based models can predict how the dune may be lowered, and how much water may flood behind it,” said Jess Gorski (MS 2023), who worked with Professor Casey Dietrich on the project. “Our forecasts can provide information about coastal change to decision makers during a storm.”

In collaboration with the USGS, CCEE researchers developed a framework for running the eXtreme Beach (XBeach) model in real time. The U.S. Gulf and Atlantic coasts are described with thousands of transects, which quantify the offshore depths and the shape of the beach and dune at intervals of 500 m to 2 km along the coast. When a storm approaches, the framework can select the transects that may be affected, and then run a few hundred simulations of the coastal erosion.