Development of a 1D Model to Simulate Overland Flow on 2D Complex Domains

This paper presents the development of a one-dimensional (1D) model, CCHE1D channel network model developed by National Center for Computational Hydro-science and Engineering (NCCHE), for overland flow simulations on two-dimensional (2D) complex domains. This study is based on the hypothesis that 1D models could be a surrogate of 2D models for overland flow simulations on 2D complex domains by mimicking 2D models in computational mesh generation; and, with one dimension reduced, the surrogate model simulation would have comparable accuracy with much higher computing efficiency. The whole study is divided into two parts: (1) the generation algorithm of 1D channel networks for 2D complex domains; and (2) the numerical simulations for verifying and validating the above hypothesis. The generation algorithm for 1D channel network follows two principles: geometrically cover the whole domain without overlapping and interception; and hydrologically follow the steepest slopes. Several benchmark cases based on laboratory and field-scale studies with complex topography were selected to demonstrate the generation algorithm and compare the CCHE1D model simulation with the CCHE2D-Hybrid model simulation. These numerical simulations demonstrated that CCHE1D model is capable of efficiently simulating overland flow on 2D complex domains with comparable accuracy using 1D channel networks generated by mimicking 2D computational meshes for 2D models, despite the limitations of 1D models in simulating complex flow structures.
This 1D surrogate modeling study of 2D overland flow simulations can be considered a pilot study for rainfall-induced flooding and soil erosion problems, where 2D hydrodynamic models may have computing efficiency concerns and 1D models could be alternative modeling choices for fast solutions with comparable accuracy. The developed CCHE1D model can be used by USDA and other governmental agencies to evaluate soil erosion control practices for agricultural land management.