THE EFFECT OF ALLOCATION SCHEDULES ON THE PERFORMANCE OF IRRIGATION SYSTEMS WITH DIFFERENT LEVELS OF SPATIAL DIVERSITY AND TEMPORAL VARIABILITY

This paper quantitatively examines the effect of spatial diversity and temporal variability on the performance of an irrigation system. The Irrigation Land Management (ILM) computer model was used to simulate o ver a 20-year period the response of four test systems constructed wit h different levels of spatial diversity and temporal variability to th ree schedules representing different levels of management flexibility. From the simulation runs it is apparent that the need for more flexib le schedules becomes greater as the irrigation system becomes more spa tially diverse and its climate becomes more variable. Choosing the rig ht schedules depends not on maximizing production, but rather on optim izing production given the costs of management and the context within which the system operates.