Abstract
This study clarified the conditions for continuation or abolishment of Irrigation Water Wheels (IWWs) over the past 30 years in JAPAN. The research approach involved interviews and measurements of the IWW components. Results of interviews revealed the reasons for abolishment were ‘upgrade to a pump’, ‘abolition of paddy use’ and ‘absence of a millwright’, whereas reasons for continuation were ‘reduction in expense and labor load are good’, and ‘good water sharing method without backwater’. Results of measurements of the IWW components showed most cases of continuation used IWWs with a diameter between 1.5 m and 2.5 m and average beneficial paddy field area of large, whereas most cases of abolishment used IWWs with a diameter more than 2.0 m and beneficial paddy field area of small. In fact, the continuation or abolishment of IWWs differs depending on their diameter and beneficial paddy field area. User of IWW judge expense of IWW on diameter of IWW and beneficial paddy field area. If diameter is more than 2.0 m, IWWs introduced from outside funds are continuously used for irrigation. In this way, over the past 30 years, the components of IWWs that are utilized have converged with expense advantage. Other conditions (i.e., absence of millwright and use for sightseeing) for continuation or abolishment were clarified as not related to expense.
