Abstract
Step-pool morphology, which is one of the most important environmental elements in mountain rivers, has been recently incorporated into channel works. From an ecological point of view, it is desirable that the materials are not covered with cement and the structure is allowed to be changeable. When we design the step-pool structure in such a sense, we should know the deformation process of the structure in floods and the critical discharge for the disappearance of the step-pool bed form. Therefore, we surveyed the changes in the step-pool structure due to the floods in the Gamata River. The structure was changed with the combination and division of the steps, but not completely destroyed by the floods. The formation and deformation process of the step-pool structure have been explained theoretically using the hydrological data.
