Over the two-day period of 19-20 July, 2003, the Kyushu area of Japan was hit with heavy rainfall, causing many kinds of disasters in various areas. A total of 1,352 houses were flooded in Fukuoka City when the Mikasa River overflowed its banks. For our research, the flooded area was estimated by a threedimensional (3D) Geographic Information Systems (GIS). A high-resolution Digital Elevation Model (DEM) (10 m meshed grid) has been integrated with GIS so as to construct a 3D GIS model in the

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... ion around the Mikasa River Basin. An area of 10 m DEM has been developed by a commercial company, which offers up to 0.1 m resolution in a vertical direction, and also covers the entire country of Japan. Resolution in the vertical direction is sufficient for construction of our model. The three-dimensional buildings database in Fukuoka City is used to construct the model, which includes 3D structure. The flooded area is estimated with great precision based on 10 m DEM according to water levels from 3.6 m to 5.0 m of the Mikasa River. Three-dimensional views of the flooded area were obtained from several view angles by this system. Recently, an airborne laser scanning system was used for generating DEM with high resolution. The sensor is able to measure distances between the sensor and Risk Analysis V: Simulation and Hazard Mitigation 265 www.witpress.com, ISSN 1743-3541 (on-line)