There are 21 main, 29 secondary and 79 ordinary rivers in Taiwan. Most of their planning, regulation and management of the midstream and downstream reaches in the rivers have been implemented by the local authorities. In the past, the probable inundation areas were defined in advance as a reference for the planning of the levee’s layout and the management of the floodplain. The insufficient accuracy of the map and indefinite methodologies associated with hydrological and hydraulic analysis induce the planning seriously deviated from the practical situation.
In this study, the various methodologies for the hydrological and hydraulic analysis needed for study of floodplain management will be examined and assessed. On the basis of the thorough understanding about the methodologies and other non-technical conditions in which may affect the management of floodplain, a preliminary guidelines for floodplain management will be proposed.