Evaluation of Alaska’s Coastal Zone Total Water Level Modeling System Developed for the Next Generation Water Resources Modeling Framework (NextGen)

The Office of Water Prediction (OWP) is currently developing a Next Generation Water Resources Modeling Framework (NextGen) that will provide Total Water Level (TWL) forecasts for most US coastal zones. This NextGen capability will allow the execution of different coastal models within user-selected domains, coupled to a common channel network. The Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM) and the D-Flow Flexible Mesh (D-Flow FM) models were initially selected to simulate TWL. The OWP coastal team has developed SCHISM and D-Flow FM models coupled to a Tree-Based Channel Routing Model (T-Route) to calculate TWL in coastal regions of Alaska.
Accurate total water level prediction in coastal regions depends on the model’s capability to use all applicable forcings within the domain. Here, we’ve forced coastal models with tidal oceanic boundaries from a global tidal model, riverine inflows calculated from T-Route, and meteorological forcing data from the Analysis of Record and Calibration (AORC) retrospective dataset or the High-Resolution Rapid Refresh (HRRR) model. We compared NOAA-predicted and observed water levels to the SCHISM and D-Flow FM simulated water levels. Initial model results suggest that the current mesh resolution and bottom roughness values are adequate to accurately predict TWL during combined river flooding and extreme tide events at a large coastal spatial scale under the NextGen framework.