Application efficiency is the primary criterion in border
irrigation system design and management. The application
efficiency function of border irrigation systems is unimodal
with respect to length and unit inlet flow rate. Optimality
conditions are derived for the Ea(L) and Ea(qo) functions.
Differences between the solutions obtained using the approximate optimality conditions derived here and the actual
optimal solutions are less than three percentage points. Given
the imprecision involved in the determination of the system
parameters and numerical errors, the results are satisfactory
for practical purposes. The advantages and limitations of
advance-phase and post-advance-phase inflow cutoff options
and their effects on design and management are discussed.
Based on the optimality conditions derived here, simple
design and management rules are developed