Authors: Fei Ye, Joseph Zhang – Virginia Institute of Marine Science, William & Mary, Eric Anderson – Colorado School of Mines, Saeed Moghimi, Zizang Yang – National Ocean Service, NOAA olvin – University of Utah
Title: From Watershed to Coast: Representing Flow Pathways in Coastal Transition Zones for Compound Flooding
Presentation Type: Lightening talk
Abstract: Recent advances in national-scale hydrologic forecasting have extended predictions into coastal regions through coupling between hydrodynamic and hydrologic models via unstructured grids. These developments enable high-resolution simulations of total water levels across broad coastal domains, representing an important step toward integrated watershed-to-coast forecasting.
While high-resolution meshes provide detailed spatial coverage, many small channels, distributaries, and low-gradient flow paths remain difficult to explicitly represent due to their scale and density. To explore this aspect, we present an integrated framework that combines hydrography-guided mesh refinement with a coupling strategy to the National Water Model (NWM), enabling distributed fluxes to be directly incorporated into the hydrodynamic model and conveyed through explicitly resolved channels.
Initial results indicate that representing both distributed runoff and the pathways through which it propagates leads to more coherent overland flow patterns and enhanced signal propagation in nearshore and low-gradient regions. These findings suggest that, in addition to resolution, the organization of flow pathways plays an important role in translating watershed-scale inputs into coastal responses.
This work contributes to ongoing efforts in integrated hydrologic–hydrodynamic modeling by emphasizing the role of connectivity in coastal transition zones, with implications for improving compound flood prediction and operational forecast systems.