CHANGING WATER CONTROL IN A TAIWANESE RICE-FIELD IRRIGATION SYSTEM.

In the early 1950's Taiwanese farmers using the Nan-hung Canal for irrigation learned that rice cultivation required less water than they had thought. After several features of their irrigation system were altered, they changed theft water control methods as practiced during periods of low water supply and so allowed significant changes in cropping patterns during the first rice crop season. Previously, farmers whose fields took water from the end portion of the canal or of long ditches spent much more time and effort in bringing water to theft fields and received less water than did farmers high in the system. The former thus could not allot as much land to wet rice as they wished. As a result of the changes, all users of the Nan-hung system now have enough water to raise rice on as much of their land as they desire. In addition, those who once expended considerable effort on water control activities now work only a little more than do farmers high in the system. Therefore, the location of a field with respect to the source of water of its ditch or the canal is no longer important in affecting its water availability. [ABSTRACT FROM AUTHOR]