A BASIC INVESTIGATION ON INUNDATION CHARACTERISTICS AND FLOOD CONTROL MEASURES IN ROKKAKU RIVER BASIN

Abstract

Rokkaku River meanders through western Saga lowland with mild slope and flows into the Ariake Sea that has the largest tidal range in Japan. A 60% of the basin is flat area and a lot of inundations occurred so far. In this study, hydraulic and hydrological analyses were executed considering inundated water inside river dykes. Moreover, by using GIS, satellite images and aerial photographs effectively, a basic investigation is carried out to construct the system to manage water optimally in whole river basin. The satellite images are used to estimate a change of land use and those are compared with inundation maps in 1980’s and 1990’s on the GIS. The aerial photographs are used for aerial triangular surveying that can obtain orthoimages and DEMs of the river basin concerned.