Collisions of Traditional Commons with the Modernized Institution of Rice-Paddy Irrigation Systems in Japan

The traditional Commons in water management, which have been called 'irrigation Commons,' has operated rice-paddy irrigation systems in Japan. The systems (irrigation facilities and Water Users Organizations) are characterized by many farmers on a small scale. The feature leads farmers to the laborious task of collectively managing the long network of irrigation facilities through WUOs. In other words, the structure of irrigation facilities as a network of canals had an effect on the structure and functions of irrigation organizations. It is called the 'stratified' structure and function, which is build up at each division works of a canal network. The features of river water resources (fluctuation and gravity/natural-flow property) also had effects on the structure and function. The former (fluctuation) leads to privileged development of rice-paddy field as 'First in time, first in right' upon a prior appropriation principle, whereas the latter (gravity/natural-flow property) does to an advantageous position of an up-stream diverter. These features provide the setting for traditional Commons and irrigation-water practices on rice-paddy field in Japan. When the modernized river water management was introduced with 1896 River Act, the traditional rice-paddy irrigation systems were expected to totally shift from 'under the local agreement' to 'by legal permission for water rights'. However, since the river-administration authority regarded the prior-appropriation water rights as 'deemed' permitted water rights in a legal system and verified the entitlement of prior-appropriation water right holders, the potential collisions and confusions were obviated. It was after the World War II when the potential collisions between traditional Commons and the modernized institutions occurred in response to the increase of demand in city and manufacturing water. The river-administration authority took several measures to prevent or reduce the impact of collisions such as construction of multi-purpose dams.