The performance framework of irrigation systems needs a clear definition for
boundaries of tlieir assessment. These boundaries include the fimctions which are performed by
the irrigation system, and the processes involved in creating and sustaining the irrigation system
during its lifetime. The geographical area corresponding to the physical or social elements of the
irrigation system is the third item of these boundaries which must be defined. This work
introduces a procedure of assessing the performance for irrigation systems. Case study was
conducted to clarify the procedure which depended on field data. The tail-end farmers are found
to be aware, from pervious seasons, that performance reliability and adequacy are poor, thus they
decided to reduce their irrigated area. A care must be talcen to choose between the performance
indicators because one indicator along is often not sufficient to describe the performance