Performance assessment is an essential component of effective irrigation management.
Regular feedback of information from the field into water management decision making
can substantially improve the performance of water delivery services. However, obtaining
repeated objective evaluations about actual field conditions is difficult. Remote sensing
may now provide viable solutions in some situations, allowing repeated sampling of field
conditions in units as small as 100 ha. By regularly monitoring field wetness indicators,
system managers can modify decisions throughout an irrigation season based on field
moisture depletion and evaporation deficit. In systems with little flexibility in operations
(for example, the extensive supply-based systems of the Indus and Ganges basins), such
monitoring would assist managers to identify persistent deviations from scheduled
deliveries enabling more rapid diagnosis of causes of deviations from target.
In addition, regular performance assessments are necessary to maintain accountability,
that is making sure that service specifications are met. Information from remote sensing
can play an important role in determining whether the actual service provided meets the
targeted specification, with the important advantage that remotely sensed data is objective
and unbiased