Error Quantification for Hurricane Storm Surge Simulations along the Coasts of North Carolina, South Carolina, and Georgia

Abstract

This paper describes the development of a procedure to quantify errors in hurricane storm surge simulations using a decoupled wind-surge model. The state-of-the-art storm surge simulation program, advanced circulation (ADCIRC), and the Georgiou’s wind-field model were used to simulate the storm surge heights associated with 169 historical hurricanes from 1922 to 2011 along the coasts of North Carolina, South Carolina, and Georgia. The storm surge modeling errors were quantified by comparing the measured with the simulated annual maximum surge heights at nine water-level observation stations maintained by the Center for Operational Oceanographic Products and Services (CO-OPS). The simulated surge heights consisted of both systematic and random errors. A power equation was used to adjust the systematic errors in the simulated storm surge heights. The random errors, which are defined as the ratio of the measured to the systematic error-adjusted simulated annual maximum surge heights, were found to follow a lognormal distribution. To confirm the validity of the error quantification methodology, the simulated annual, 5-year, and 10-year maximum surge heights were adjusted using the modeling errors quantified for each of the nine CO-OPS water stations and compared with the actual storm surge observations. Good agreements were observed between the actual measurements and the error-adjusted surge elevations. The proposed methodology for quantifying modeling errors can be applied to adjust for storm surge predictions of longer return periods and can be used to develop design surge hazard maps.