Irrigation lateral hydraulics with the gradient method

D. Zerihun, C. A. Sanchez

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Laterals constitute the basic element of a field-scale pressurized irrigation hydraulic network. The availability of accurate and robust computational methods applicable to lateral hydraulics is, therefore, essential for the development of pressurized-irrigation system management models. Existing water-distribution network analysis models with provisions for computing pressure-dependent outflows along pipelines can be used to simulate flows in irrigation laterals. However, such models cannot be readily customized into an efficient hydraulic module of a coupled field-scale pressurized-irrigation system management model, because of their level of complexity and other practical difficulties related to program development and maintenance. This suggests that hydraulic simulation modules, specifically designed for irrigation laterals, need to be developed for applications in pressurized-irrigation system modeling. Simulation models were developed for irrigation laterals based on computational methods used in hydraulic manifolds. Alternatively, a lateral can be conceived as a branched hydraulic network and the hydraulic simulation problem of an irrigation lateral can then be formulated based on standard network analysis techniques. There is some ground to presume that, among applicable pipe network analysis techniques, the gradient method produces a more general and robust formulation of the hydraulic simulation problem. Thus, the objective of the study, presented here, is to develop a hydraulic simulation model for irrigation laterals, based on a standard network analysis technique (specifically the gradient method), and to evaluate the model. Accordingly, for computational purposes an irrigation lateral is described as a branched hydraulic network with links and nodes. Lateral pipe segments and emitters or riser-emitter assemblies, as the case may be, are treated as links. The network nodes are comprised of junction nodes with unknown heads and fixed-head nodes with given heads. The link energy balance and the nodal continuity equations describing flow over the entire lateral are coupled to form a nonlinear system, which is solved iteratively for the variables: link discharges and nodal heads. The hydraulic simulation model is evaluated through comparisons of model outputs with field data and outputs of an existing model.

Original languageEnglish (US)
Article number04017023
JournalJournal of Irrigation and Drainage Engineering
Volume143
Issue number8
DOIs
StatePublished - Aug 1 2017
Externally publishedYes

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Water Science and Technology
  • Agricultural and Biological Sciences (miscellaneous)

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