Date of Award

7-2020

Document Type

Thesis - Open Access

Degree Name

Master of Science in Civil Engineering

Committee Chair

Stephen Medeiros, Ph.D., P.E.

First Committee Member

Jeff Brown, Ph.D.

Second Committee Member

Marwa El-Sayed, Ph.D.

Abstract

Current storm surge modeling typically uses local land use land cover (LULC) maps coupled with lookup tables to parameterize surface roughness because the process is defensible and easily automated at the regional scale. However, this is not a truly accurate method since LULC data is generalized for an area and often contains misclassifications. Intra-class variability is also a concern as variations in obstacle density within LULC classifications are prominent at typical storm surge model resolution scales ranging from 20-meters to 200-meters in the floodplain. Using lidar data, topography and the 3-dimensional structure of above-ground obstructions can be more accurately characterized, which we hypothesize will result in more realistic storm surge behavior in the floodplain. The analysis focused on the landfall area of Hurricane Michael (2018), specifically the coastal region of the Florida Panhandle and Gulf of Mexico in Bay and Gulf County. Lidar data collected in 2017 by the Northwest Florida Water Management District, were processed using ArcGIS, Python, LAStools, and a random forest model to calculate spatially variable Manning’s roughness coefficients (n). This is the first time the process has been applied at the multi-county scale. Using the numerical hydrodynamic modeling code ADCIRC, an unstructured finite element mesh (NGOM-RT) was used to simulate storm surge using both the lidar based Manning’s n and a comparative LULC-based Manning’s n. Once modeled, the values were compared and determined to be statistically different, with the floodplain velocities showing a larger degree of difference than maximum water surface elevations. The results indicate that realistic and descriptive bottom friction parameterization is an influential component of simulated storm surge behavior in the floodplain and should be investigated further. (This material is based upon work supported by the U.S. Department of Homeland Security under Grant Award Number 2015-ST-061-ND0001-01. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Department of Homeland Security.).

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