Shirakawa-Weir and Haguro-Weir are the water utility facilities to irrigate rice fields on Annogawa-River Basin of the Right Bank District of Aganogawa-River, and they also have the structures to overflow the water when the flood runoff is larger than the design flood discharge or when it is predicted that the flooding would collapse the downstream levee.
However the operation rules of these weirs have not been widely recognized to the residents in this basin, so that in emergency these weirs have not been operated as rules and their functions could not be fulfilled enough.
River Act was amended in 1997 in order to add a forest belt as a flood control facility.which allows the water to overflow, to reflect residents opinion and so on.
In this paper, we describe the relationship between the history of the flood control of the Right Bank District of Aganogwa-River and the construction of Annogawa-River, then evaluate the roles of these two weirs contemporarily.