Recently species depended on floodplain have been greatly decreasing and restoration of floodplain is recognized important and urgent issue in Japan. Backwaters and ponds in the Kikuchi River, which have a part of function of flood plain, have been decreased and living things depended on them have been also reduced.

The purposes of this research are the following.

1. Evaluation of status of temporary water area in the Kikuchi River channel, which have a function of floodplain, backwaters, ponds, second flow and so on.

2.  Clarify the relationships between physical environment of them and fish fauna.

In the former, we comprehend each changes for the distribution of floodplain ponds, transverse shape, river width/depth ratio, the area of the dead water region and low velocity area by using aerial photograph (1959, 2009) and cross-sectional surveying results (1963, 2012). 

In the latter, we investigated the 10 place of floodplain ponds of lining segment 2-1. As a result, it shows that the area is more than 300m² of floodplain ponds to function as floodplain depend species habitat.