Rapid expansion of Salicaceous species in the Asahi River has caused serious problems on the ecology, the flood control and the river landscape etc. in the last 30 years. From this viewpoint, this paper aims to clarify the development process of the thick growth of trees in the river, and to propose appropriate measures how to control the forest of Salicaceous species to keep the Asahi River in its original shape. The relationship between the physical actions and landscape transition in the river was investigated on the basis of historical studies from the viewpoint of morphology, river engineering and ecology using the past physical events. Continuous expansion of Salicaceous species due to the decrease of the flood scale and bed-loads supply was recognized. At some area in the river, restoration of the river system is required to recover the flood flow impact. In applying the river restoration system, it is suggested that an appropriate method to manage the river landscape is to divide the river in two areas whether to keep its original landscape or not.