Considering tco, L, and qo as the three border irrigation
design and management variables, the border irrigation
design and management procedure can be simplified substantially. Given a parameter set and the condition Zmin = Zr,
tco is a function of qo and L. Consequently, tco cannot be
treated as an independent variable in itself. This leaves only
qo and L as the design variables. In addition, for a given field
length and parameter set combination, the set of all
practically realistic values of L is limited to a couple of
known alternatives. For each feasible value of L, Ea can
therefore be optimized with respect to qo. In which case, the
two-dimensional problem is reduced to a series of onedimensional optimization problems. The following optimal
design procedure is proposed