Border Advance Using Improved Volume‐Balance Model

A simple cost‐efficient model is developed to predict advance phase in border irrigation. Assuming a power function for the water‐depth profile, a volume‐balance equation is applied using an adjusted surface shape factor. In addition, the zero‐inertia motion equation is evaluated at the upstream end of the border. A system of two equations containing two unknowns (the advance position and the water depth at the head of the border) is thus constructed and solved at each time step. Comparison of dimensionless advance trajectory and surface‐profile solutions indicate that predictions of the present method are in agreement with zero‐inertia solutions. The proposed model is also tested for four well‐documented field irrigations. It is shown that even for level or small slope borders for which the traditional volume‐balance models give poor results, the proposed method is accurate. Programming requirements and computation cost of the present method are significantly less than for sophisticated models.