Use of 1D Unsteady HEC-RAS in a Coupled System for Compound Flood Modeling: North Carolina Case Study

Abstract

The research presented herein develops and compares an ADCIRC and ADCIRC/HEC-RAS (1D) paired model for the purpose of compound flood modeling within the Tar River and Pamlico Sound basins of North Carolina. Both the ADCIRC and 1D HEC-RAS models are capable of simulating river systems but differ in their underlying numerical formulations. A case-study comparison of each model’s ability to simulate flooding accurately and quickly in a riverine/estuarine system is investigated herein; results may serve as a valuable reference to forecasters and model developers. Individual models of the Tar River and Pamlico Sound area in North Carolina were used, and pairings of these models were devised to determine the benefits and drawbacks of using ADCIRC alone, or ADCIRC + 1D HEC-RAS, to simulate the response of the Tar River and Pamlico Sound during three test events: Hurricane Irene, Hurricane Floyd, and an unnamed April 2003 event. With increased emphasis on predicting total water levels, the results of this study can provide information for the possible development of similarly paired models for coastal river systems across the US and improve the body of knowledge about each model’s relative performance in riverine and estuarine areas.