Building Foundations for Continental River Dynamics Modeling: Saint-Venant Simulations of Texas River Networks

Abstract:

Reduced physics (e.g., Muskingum) approaches are commonly used for one-dimensional (1D) network modeling in continental-scale river basins. Such methods are computationally efficient for large systems, require minimal geometric data, and have fewer numerical instability issues than Saint-Venant solvers. However, such models cannot represent all the important physics in a river network. Furthermore, they cannot correctly incorporate new sources of high-resolution data because they neglect processes driven by fine-scale physics. Fortunately, the latest generation of supercomputers are more than adequate for modeling continental-scale river basins with the full Saint-Venant equations. Unfortunately, there remain several practical challenges to raising the numerical complexity and physics represented in river network models.

Herein, we model the 10 regional river networks of Texas using a Saint-Venant solver. The model development and demonstration results are used to examine the challenges for high-resolution Continental River Dynamics modeling. These issues include:(i) bathymetry data availability and quality, (ii) numerical instabilities from multiple, overlapping sources, (iii) time-space ac- curacy of runoff and groundwater exchange, (iv) practical spin-up for initial and boundary conditions, and (v) roadblocks to model performance. This study outlines how the community can begin building the next generation dynamic capabilities to extend the National Water Model.

Acknowledgement: This work was developed under Cooperative Agreement No. 83595001 awarded by the U.S. Environmental Protection Agency to The University of Texas at Austin. It has not been formally reviewed by EPA. The views expressed in this document are solely those of the authors and do not necessarily reflect those of the Agency. EPA does not endorse any products or commercial services mentioned in this publication.