Development of a Mathematical Model of Lopac Gates in Accordance with the ICSS Hydrodynamic Model.

A Lopac gate is one type of upstream control structures in irrigation canals. Advantages of a Lopac gate include performing as an overflow structure, letting sediments and floating bodies pass simultaneously, as well as easy automation. The structure has recently attracted the attention of researchers for detailed investigations. One effective tool to study control structures is a mathematical model. Due to the unsteady nature of flow in irrigation canals, incorporation of the mathematical model of control structures with hydrodynamic models is necessary. In this research, a mathematical model of Lopac gates is developed and linked with the ICSS (irrigation conveyance system simulation) hydrodynamic model. The Lopac gate model was developed as a boundary condition in four subroutines, including steady flow conditions, operation, unsteady flow conditions, and updating information. The developed model is validated using physical model data. The maximum error obtained was 6%, which is acceptable for practical purposes. The model was tested on a canal of DEZ irrigation network in Iran under many different conditions. The results showed that the model is performing well for tested applications and could be used in various studies of irrigation canals equipped with this structure. [ABSTRACT FROM AUTHOR]