河床変動の影響を考慮した氾濫水の排水対策

抄録

Drainage problem of inundated water on the lower Chao Phraya River in Thailand is introduced. Furthermore, drainage methods of inundated water on low flat land areas have been discussed by use of horizontal two dimensional bed deformation analysis. Construction of shortcut channel in the fully developed meandering channel can decrease the water surface elevation in the upstream area of the shortcut channel. However, water surface level increases in the downstream area and risk of inundation increases in the downstream area of the shortcut channel. Most of the connection points between the Chao Phraya River and irrigation channels are located along the outer bank. However, water surface level along the outer bank is higher than that along the inner bank during floods. As a result, drainage of inundated water from the irrigation channel to main channel will increase, if the connection points between the main flow and irrigation channels are located along the inner bank. Furthermore, a groin at the upstream of the connection points between the main channel and irrigation channels can decrease the water surface level at the connection points between the main and irrigation channels. As a result, drainage discharge of inundated water from the irrigation channel to the main channel increases.