Integrated Coastal Urban Flood Modeling, Applications, Lessons Learned, Future Directions

The mission of the U.S. Army Corps of Engineers’ (USACE) Coastal & Hydraulics Laboratory, a part of the Engineer Research and Development Center (ERDC), is to deliver solutions to our nation’s most challenging water resources problems through research, development and application of cutting-edge science, engineering and technology. One such challenging area is coastal urban flooding. Coastal urban flood modeling has historically been approached from two separate sides, the coastal side and the inland hydrology side with very limited interaction between the two modeling domains.

This myopic approach leaves unresolved significant complex flooding risks due to the interaction between storm surge and waves from the coastal regime and rainfall, runoff, streamflow, drainage systems from the inland side. In many cases, storm surge is considered the largest risk for coastal flooding, however recent events, such as Hurricane Harvey, have demonstrated that other factors may play a large role in flooding risks. Emphasizing that the true risk can only be assessed by analyzing the combined effects of many sources of flooding, and the nonlinear interactions between them.

The ERDC has performed soft linkage of coastal and overland flow models, namely ADCIRC (Advanced Circulation) and GSSHA (Gridded Surface Subsurface Hydrologic Analysis) in an effort to provide information during coastal events such as Hurricane Sandy and Hurricane Harvey, as well as other applications both CONUS and OCONUS. These applications provided useful and timely information for planning and operational needs to USACE districts.

In this presentation, we will utilize some of these previous efforts at coupled storm surge and hydrology modeling to discuss the methods, difficulties, and results from these efforts. We will discuss ongoing and planned research, which includes efforts to improve the individual models for such simulation scenarios, as well as efforts to implement two-way exchanges of data through dynamic model coupling systems such as the Coastal Storm Modeling System (CSTORM-MS), which will allow for real time information exchange between the two sides to coastal urban flood modeling.