Topobathymetric Estimation for 2D Hydraulic Models

Follum Hydrologic Solutions (FHS) completed a two-year research and development project for the U.S. Army Engineer Research and Development Center (ERDC) to advance methods for generating topobathymetric datasets suitable for advanced two-dimensional (2D) hydraulic models. The project addressed a persistent challenge in hydraulic modeling: the lack of reliable river bathymetry within commonly available elevation datasets. Building on prior work with the SPT–AutoRoute–FloodSpreader framework, FHS developed preprocessing tools and workflows that transform digital elevation models into hydraulically consistent topobathymetric surfaces using readily available baseflow streamflow data. Central to this effort was the development of the DEM_Cleaner tool and enhancements to the Automated Rating Curve (ARC) framework, which together correct non-physical water surface artifacts and estimate realistic channel bathymetry.

FHS rigorously tested the resulting topobathymetric surfaces within advanced 2D hydraulic models, including HEC-RAS 2D and Adaptive Hydraulics (AdH), across multiple sites in both the continental United States and international basins. Testing demonstrated how different bathymetric assumptions influence predicted water depths, velocities, and flood extents across a range of flow conditions. The project delivered fully documented preprocessing scripts, example model implementations, updated user documentation, and a peer-reviewed journal article published in Environmental Modelling & Software. Together, these outcomes provide water managers, engineers, and military planners with a scalable, defensible approach for initializing advanced hydraulic models in data-sparse environments, significantly expanding the practical deployment of 2D flood modeling capabilities worldwide.

https://doi.org/10.1016/j.envsoft.2025.106487