ABSTRACT
Paddy irrigation is different in at least two basic physical parameters that substantially affect the design and operation of irrigation management systems. The theory to be advanced here is that because of these two physical parameters, paddy irrigation systems have a self-regulating property that leads to a reasonably optimal allocation of water supply between farmers. Thus, in complete contrast to other crops, it is doubtful if management improvements in the form of rationing and rotation of water supply to farmers would result in cost-effective improvements over the allocation achieved by naturally functioning, laissez-faire systems. A commonly perceived problem in paddy irrigation is high water depth in paddy fields at the heads of the system, while tail enders are subject to water stress. The economic constraint on over-irrigation is the labor and land cost of building and maintaining dikes for water storage.
