Acceso usuarios
Manoj Khanna, Hector M. Malano
Basin irrigation layouts are used extensively for irrigation of various types of crops worldwide. Basin irrigation is characterised by ground levelled to zero slope in both directions and each unit enclosed by dykes. Single closed level basins and sequential multiple basin layouts offer potentially high uniformity of application, reduced runoff and low labour requirements. Several simulation models have been developed to study the flow processes involved during an irrigation event in basin irrigation to improve the design and operation of these basin layouts. These simulation models are based on governing equations in the form of the full hydrodynamic Saint�Venant equations or the simplified zero-inertia approximation (neglecting inertial terms). This paper reviews various simulation models that have been developed and discusses various issues involved in modelling of basin irrigation layouts. Application of these models for use in the design and management of basin irrigation layouts is also discussed. It is concluded that two-dimensional rather than one-dimensional models are required to simulate all the flow processes involved in irrigation events in basin systems due to the non-linear nature of flow over the basin. Inclusion of basin topography through soil surface elevation even in laser levelled basins improves the quality of simulation and prediction of performance parameters. The availability of accurate values of surface irrigation parameters such as Manning's roughness coefficient and infiltration coefficients for the empirical equations is often a problem in the application of these models.
