Effect of gate selection on the non-cohesive sedimentation in irrigation schemes

In order to cover the crop water requirements, flow control structures such as gates and weirs are used to transfer the desired amount of water from the canals to the field canals. This paper examines the impact of gate operation and the selection of gates on the deposition of non-cohesive sediment. The Delft3D model is used to simulate the effects of different scenarios regarding gate operation and the location of the gate that is opened. The model results showed that the gate selection affects not only hydraulic parameters but also morphological parameters. It was found that opening the gates closer to the offtake resulted in less sediment deposition at the entrance of the branch canal when compared to opening the gates further away. Gate selection can be used as a tool in sediment management. By alternating the opening of different gates sediments that are already deposited after opening one gate can be eroded when another gate is operated, thus minimizing the additional cost of sediment removal. The use of Delft3D proved beneficial as the selection of different gates leads to asymmetric sediment deposition patterns which would be missed when using a 1D model