Chang K.-HTSANG-JUNG CHANGGarcia M.H.2021-07-262021-07-262021221686https://www.scopus.com/inward/record.uri?eid=2-s2.0-85102940992&doi=10.1080%2f00221686.2020.1866689&partnerID=40&md5=f14f2c0c7165970443faaf9451f8afb9https://scholars.lib.ntu.edu.tw/handle/123456789/573030A well-balanced and positivity-preserving meshless method based on smoothed particle hydrodynamics (SPH) is developed to simulate one-dimensional (1D) and two-dimensional (2D) shallow water (SW) flows in open channels with irregular geometries. A new form of the characteristic equations that govern the water-surface level and water velocity is introduced to specify the numerical inflow/outflow boundary conditions. An additional condition, derived from temporal discretization to determine the time-step size, forces the water depth to be positive. A 1D finite volume shallow water (FVSW) model based on the first-order Godunov upwind method is built to conduct a comparison of the 1D meshless-based and mesh-based SW models. Six benchmark cases–still water, single trapezoidal and rectangular and prismatic and non-prismatic channels, and a dendritic channel network–are employed to validate the proposed models and compared with the exact and mesh-based numerical solutions. A real-world case of the Chicago Area Waterways System (CAWS) is investigated to highlight the performance of the proposed 1D model for a practical hydraulic system. ? 2021 International Association for Hydro-Environment Engineering and Research.Hydraulic equipment; Mesh generation; Open channel flow; Silicon compounds; Characteristic equation; Irregular geometries; Numerical solution; Positivity preserving; Shallow water flow; Smoothed particle hydrodynamics; Temporal discretization; Two Dimensional (2 D); Hydrodynamicsjournal article10.1080/00221686.2020.18666892-s2.0-85102940992