Generation of 1D channel networks for overland flow simulations on 2D complex domains

Authors: ZHANG, YAOXIN - University Of Mississippi; AL-HAMDAN, MOHAMMAD - University Of Mississippi; Bingner, Ronald - Ron; CHAO, XIAOBO - University Of Mississippi; Langendoen, Eddy; Vieira, Dalmo

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2023
Publication Date: 12/8/2023
Citation: Zhang, Y., Al-Hamdan, M., Bingner, R.L., Chao, X., Langendoen, E.J., Vieira, D.A. 2023. Generation of 1D channel networks for overland flow simulations on 2D complex domains. Journal of Hydrology. 628:1-15. https://doi.org/10.1016/j.jhydrol.2023.130560.
DOI: https://doi.org/10.1016/j.jhydrol.2023.130560

Interpretive Summary: Two-dimensional (2D) models are more time-consuming than one-dimensional (1D) models, although they can provide more accurate results. This study proposes a 1D model to work as a surrogate 2D model for rainfall-induced flow in order to improve computing efficiency. This 1D model can provide comparable results but with much higher efficiency. To enable a 1D model for flow simulation on 2D domains, the first step is to generate 1D channel networks for 1D models. The channel network consists of channel nodes, channel reaches, and channel links, which 1D models can then be used simulate flow simulations. This work describes the development of an algorithm for 1D channel network generation to cover the study domain. The proposed generation algorithm of 1D channel networks was applied to overland flow conditions typically utilized on a complex 2D domain. Comparable simulation results from the 2D model were obtained by the 1D model, demonstrating the capabilities of applying the 1D approach on complex hydrologic conditions.

Technical Abstract: Conventionally two-dimensional (2D) models are used to simulate 2D overland flow with a non-overlapping 2D computational mesh. However, 2D models are not computationally efficient when applied to large domains. Due to their computing efficiency, one-dimensional (1D) models can be used to simulate 2D overland flows by replacing 2D computational meshes with 1D computational channel networks with topography described by closely-spaced transverse cross sections that fully cover the whole domain. Channel networks must enforce the basic physical laws of gravity-driven flows ensuring water flow paths converge and connect from high to low elevations. This manuscript presents a novel algorithm to generate channel networks following two principles, a geometric principle and a hydrologic principle. The geometric principle requires that the generated channel network covers the whole study domain without overlaps or intersections, while the hydrologic principle requires that the generated channel network follows the local steepest slope. Correspondingly, the proposed generation algorithm includes two main processes: (1) the extraction of channel network using a terrain slope-calculation-based delineation algorithm; and, (2) the generation of cross sections with varying channel widths determined by considering topographic complexity, the hydrological correctness, and computational requirements. The proposed cross section generation algorithm is described using several 2D geometrically complex domains at the laboratory scale, and is also applied to a natural watershed. An overflow simulation on a 2D domain with obliques walls using a 1D model demonstrated the effectiveness of the proposed generation algorithm for 1D channel networks of 1D model.