From upstream to real time management: research for modeling in a surface irrigation system

Abstract

The Sorraia Irrigation Project is a well operated surface irrigation system but conceived decades ago. Modernization is needed to increase conveyance and distribution efficiencies, to improve flexibility of the system, to adequate it to modern exigences needs, to provide improved utilization of available water and other natural resources. This is not possible maintaining traditional upstream control but implementing an intelligent upstream control with real time management. To do so ,many research lines are being developed and this report concerns essentially the modeling approaches relative to the simulation of the canal system and the simulation of farm irrigation in the project area. The hydraulic simulation of the canal system presents particular aspects since the automatic gates of constant upstream level constitute a specific problem for the application of the Saint Venant equations to describe the unsteady flow. the paper concern some research approaches that are most interesting since they may provide the basis for the required adoption of remote control and the application of real time operation: i) field calibration of a model using a combination of the continuity equation and of a discharge equation to simulate the behavior of the automatic constant upstream level gates; ii) field calibration of a numeric model for the junctions of canals, transitions of size and form of canals, siphons and gates; iii) build-up of an aggregate hydraulic simulation model for the complete system. Concerning the simulation of farm irrigation to build-up a management model governing reservoir releases, control points and deliveries to the distributaries, studies cover several aspects: i) improvement of model AGREGA for simulation of water consumptions and needs; ii) a data bank with meteorological, soils and crops data and irrigation data relative to the command area; iii) the irrigation simulation model ISAREG; iv) the development of an irrigation decision model to be applied at each distributary, GESREG; v) the aggregated and iterative use of such models to simulate the spatial water requirements and, therefore, release and deliveries. this case study do not present ultimate solutions but specific research steps essential to achieve them. Therefore, this report can be of particular interest for those who want to introduce real time management and need to investigate the solutions to be adopted.