Abstract
One of purposes of this study is to show a mechanism of flood damages which can be expressed by the combinations of factors with natural circumstances, social circumstances and both contactual circumstances.
Further more the position of flood damages is established with three axises which are the time, the space and the subject axis.
Another purpose is to build up the System Dynamics Model evaluting the interaction between the investment for flood control and the flood damages reduced by the investment. By using this model the dynamic effectiveness of the flood control projects and the influences of the expanding land use can be measured.
Now there is two types of the flooding as follows:
1) The overflow caused by abnormal precipitation or snowmelt and in result blinging on abnormal stream of the river.
2) The storm drainage caused by runoff from small urban areas.
In order to reduce the damages with the overflow some structural measures, for example, reservoirs, channel inprovements, levees, bypasses and so on, is constructed with the investment.
And pumping plants and gates are considered to reduse the damages with the storm drainage.
In this analysis we use levees and pumping plants which are most ordinary in all the methods.
