Abstract
To investigate the proper design of runoff control device adopted in Mitsuke city, Japan, where paddy field dam has been promoted, this study firstly, classified the existing runoff control devices into “function-integrated” and “function-independent” type to compare their advantages and disadvantages; secondly, introduced the basic design concept of a new runoff control device suitable for the conventional cylindrical drainage outlet; and finally, evaluated flood mitigation effect of the newly developed device. The following superiorities of the function-independent device in which the function of runoff control and water management are mutually independent became clear; (1) a sustainable runoff control performance under heavy rainfall events, (2) minimal disruption to the farmers' daily water management practices under small rainfall events, and (3) stable runoff control function due to little influence of paddy field water level changes. In response to these superiorities, authors fundamentally reexamined the structure of the runoff control device already adopted in Mitsuke city, and developed a new function-independent device suitable for the cylindrical drainage outlet. As a result of the evaluation by computer calculation, it became clear that the new device presented a better performance in functionality and sustainability than the conventional one.
