Riverbed is consisted of various habitat types, e.g., riffles, pools, side pools, back waters, etc. These habitats are changing in time and space by deposition and erosion processes caused by floods. These processes should be appropriately considered in the ecological evaluation. This article discusses riverbed characteristics of spawning redds for Ayu (Plecoglossus altivelis altivelis), in relation to changing patterns of habitats in the Tenryu River, Japan. Habitat surveys were conducted to understand the riverbed characteristic by comparing physical parameters of spawning redds with other habitat types, e.g., water quality, riverbed softness, grain size distributions, photo data via interval-recording-cameras, aerial photo data, etc. It also examines effectiveness of sediment replenishment options, applying a 2D riverbed variation model. Two options of renewing an existing riffle at main channel and creating a new riffle and spring water at a secondary channel are discussed.