Improving Accuracy of Real-Time Storm Surge Inundation Predictions

Emergency managers rely on fast and accurate storm surge predictions from numerical models to make decisions and estimate damages during storm events. One of the challenges for such models is providing a high level of resolution along the coast without significantly increasing the computational time. Models with large domains, such as the ADvanced CIRCulation (ADCIRC) model used in this study, are accurate in predicting water levels and their variation in complex coastal regions, however their spatial resolution may limit their predictions of flooding at the scale of buildings, roadways, and critical infrastructure.

A new tool has been developed that uses Geographic Information System (GIS) scripts to enhance the resolution of maximum water level predictions at the boundary of predicted flooding using a high-resolution Digital Elevation Model (DEM). The water levels predicted by the lower resolution model are extrapolated outward to where the water would intersect with the higher resolution elevation dataset. The result is a highly-refined flooding boundary that represents inundation on scales smaller than the typical ADCIRC mesh resolution. This tool can process a 15-m DEM for all 32 coastal counties of the state of North Carolina in less than 15 minutes during a storm event.

Comparison of results using spatial building datasets showed that for a simulation of Hurricane Matthew, 2,353 buildings were predicted to be flooded in Carteret County, NC, prior to enhancing resolution and 3,298 post-enhancement, an increase of 40 percent. In Dare County, the increase was 22 percent. This dramatic increase in flooded buildings shows the importance of achieving high accuracy in floodplains, as a relatively small change in predicted flooding extent can have a substantial impact on the predicted number of flooded buildings. The validity of these results was tested via comparisons to results of an ADCIRC model with the same 15-m resolution as the DEM in Dare County. Dare County is a coastal region with widely-varying topography and land cover, and preliminary comparisons have shown that the GIS method is accurate in coastal regions with steeper slopes and less accurate in flatter, low-lying areas.

N Tull (2018). “Improving Accuracy of Real-Time Storm Surge Inundation Predictions,North Carolina State University.

News: Improving Coastal Flooding Predictions

2018/05/14 – NC Sea Grant Coastwatch Currents
Hurricane Hindsight: Researchers Work to Improve Coastal Flooding Predictions

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Computer models can make surge predictions based on limited information about storm characteristics such as track, size, maximum wind speed and central pressure. Those parameters are used to predict the surface pressures and wind speeds throughout a coastal region. Those atmospheric conditions are then used to predict how the ocean will respond by generating large waves and surge, and by flooding into low-lying areas.

Given all the variables involved, there’s a lot of room for error in storm wind and surge prediction modeling.

For our study, we wanted to know how forecasting errors affect subsequent coastal flooding predictions. To that end, we needed to answer a couple of questions: First, as a storm moves closer to the coast, how accurate are forecasts of certain storm parameters like track, size, and maximum wind speed? Second, how do those forecasts affect predictions of wind speeds and storm surge?

News: Outstanding Teacher Award

2018/05/14 – NCSU Civil, Construction, and Environmental Engineering
Two CCEE Professors inducted into the Academy of Outstanding Teachers

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Teaching students from a wide range of experiences and interests, Dietrich has incorporated dynamic, team-based methods in his courses. He believes that students learn best by doing, and encourages students to become active participants in the classroom. Using required reading to introduce students to course material, Dietrich uses class time to move toward incorporating the material into an activity or problem, which is addressed in teams. He prefers his class sessions to be more discussion oriented, and for students to experience the material in a supportive atmosphere.

2018/05/03 – NCSU College of Engineering
Bryant, de los Reyes, and Dietrich receive Outstanding Teaching Awards

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[Dr. Dietrich] has contributed to the teaching mission of the department with his teaching of required courses, restarting the department’s teaching and research program in coastal engineering and improving the teaching of fluid mechanics at all levels. A former student wrote: “Dr. Dietrich is a fantastic professor and organizes his class in a refreshing way. Everything is posted online and all one needs to do is fill in the work for the examples. He is clear and concise when presenting the material and values the opinions of all the students. He emphasizes group work, which is realistic in the real world.”

2018/04/11 – NCSU Executive Vice Chancellor and Provost
2017-2018 University Teaching Awards Presented

NC State recognized more than 30 faculty for their dedication to teaching, mentoring and innovation at the 2017-2018 University Teaching Awards Ceremony on April 4. The Outstanding Teacher Award was presented to the following faculty members:

  • Casey Dietrich, Department of Civil, Construction, and Environmental Engineering

The award recognizes excellence in teaching at all levels. Faculty must receive the Outstanding Teacher Award in order to be eligible for the Board of Governors Award for Excellence in Teaching and the Alumni Distinguished Undergraduate Professor Award. Recipients of the Outstanding Teacher Award become members of the Academy of Outstanding Teachers for as long as they remain NC State faculty. Recipients’ names are published in the commencement program.

Conference: ADCIRC 2018

R Cyriac, JC Dietrich, A Fathi, CN Dawson, KM Dresback, CA Blain, M Bilskie, SC Hagen, H Graber. “Wind Effects on the Choctawhatchee River Plume at Destin Inlet, Florida.” ADCIRC Users Group Meeting, NOAA Center for Weather and Climate Prediction, College Park, Maryland, 13 April 2018.

A Thomas, JC Dietrich, JG Fleming, BO Blanton, T Asher, RA Luettich. “High-Resolution Modeling of Surge during Hurricane Matthew.” ADCIRC Users Group Meeting, NOAA Center for Weather and Climate Prediction, College Park, Maryland, 13 April 2018.

N Tull, JC Dietrich, TE Langan, H Mitasova, BO Blanton, JG Fleming, RA Luettich. “Improving Accuracy of Real-Time Storm Surge Inundation Predictions.” ADCIRC Users Group Meeting, NOAA Center for Weather and Climate Prediction, College Park, Maryland, 13 April 2018.

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CCHT Joins COPRI Field Trip to Wilmington-Area Beaches

CCHT members led the annual field trip by the Coasts, Oceans, Ports, and Rivers Institute (COPRI) student chapter at NC State University. The chapter traveled to Wilmington, NC, over two days to visit beaches from Ocean Isle to Kure through Wrightsville. The students learned about beach management practices from Greg Williams and his team at the Wilmington District of the US Army Corps of Engineers, as well as from NC Sea Grant extension specialist Spencer Rogers.

During the first day of the visit, the students visited an active dredge as it finished a beach nourishment project on Ocean Isle. The tour included a visit onto the dredge to learn how it operates, and also to the beach to see how the pumping is controlled and how the sand is worked to meet the design specifications. During the second day, the students visited several beaches closer to Wilmington to learn about terminal groins, nourishment projects, inlet stabilization, and construction practices.

This was the second annual field trip for the COPRI student chapter. During the 2017-2018 academic year, CCHT members served as President (Nelson Tull), Vice President (Rosemary Cyriac), and Treasurer (Alireza Gharagozlou).

Students preparing to board the dredge near Ocean Isle, during the 2018 COPRI field trip.

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