Analysis of microirrigation systems using a lateral discharge equation

Our objective was to develop an accurate, simple and quick method for analyzing the hydraulics of microirrigation submain units using the finite element method. A lateral discharge equation was developed to express the relationship between the discharge and pressure head at the inlet of a lateral. The lateral discharge equation allows a lateral to be represented as a point sink and the submain as a lateral. The methodology we used provides a symmetrical tridiagonal stiffness matrix which is easy to solve and requires minimum computer memory. Initially all nodal pressures are set equal to the inlet pressure head of the submain. The pressure head distribution along the submain is then determined The pressure head distribution along each lateral is next obtained since the inlet pressure head is already known. By implementing this procedure, the hydraulics of any submain unit, even if it has many emitters (four millions emitters or more), can be analyzed using a personal computer.