Development of models for analysis of flow through structures made of coarse porous media such as rockfill dams, breakwaters, sand filters and gabions has always been a research topic of interest. In this study, the structure of an equivalent pipe network model (EPNM), for analysis of steady two-dimensional (2D) nonlinear free surface flow through a homogeneous isotropic coarse porous media was investigated. The proposed EPNM consists of orthogonal pipes where flow through the pipes simulates flow through porous media. Physical and geometrical characteristics of the EPNM such as diameter, length and friction factor of the pipes are identified according to the porous media characteristics e.g. porosity, mean particle size and friction factor in the turbulent region of flow. A set of available experimental data for two physical models including a rectangular rockfill structure and a rockfill structure with inclined upstream and downstream faces, was used to verify accuracy of the EPNM. Application of the proposed model in a rockfill structure with inbuilt spillway was also studied. In this case, the EPNM results were compared with those of a finite element computer code developed in this study for modeling nonlinear flow through dams with inbuilt spillways. The results showed that the EPNM was capable of accurately determining both water surface profile and discharge through rockfill structures. In general, the EPNM, as a new approach for 2D analysis of flow through coarse porous media, employs the methods developed for water distribution network analysis, and as a numerical tool, can model free surface flow through complex rockfill structures such as rockfill dams with inbuilt spillways.

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