Validation of the effect of landside water drainage in Ushizu River basin and future flood control measures

Hisanobu Terao

Tuesday 30 june 2015

12:54 - 12:57h at South America (level 0)

Themes: (T) Flood risk management and adaptation, (ST) Flood risk assessment, Poster pitches

Parallel session: Poster pitches: 5J. FloodRisk - Assessment

In recent years, flood caused by unpredictable heavy rain becomes frequent. Lowlands greatly influenced by the tide. The difference between the ebb and flow of the Ariake Sea also extends to 6 meters. Therefore, inland water remains long time without being discharged to rivers. As a result, flood damage will increase. Flood control measures are difficult. Therefore, tremendous damages caused by flood water and inland water have occurred in lowland. In Ushizu River, pumping stations and retarding basins were built as countermeasures to reduce the damage. However the damage still occurs. Study of the effect of reducing the riverine water level by the retarding basins has been performed. There is few research about reduction of water level considering both the riverine water level and inland water level. In this study, we examined the flood control measures in the future by reproducing the flow condition of Ushizu River in Northern Kyushu heavy rains in July 2012. The effective verification of Mutabe retarding basins, and drainage pump station are executed. After evaluation of the effect of reducing the water level by seven drainage pump stations in order to solve the current problems. Water level had exceeded the estimated high-water level in the medium scale flood. Mutabe retarding basin can not cover the revealed flood. As a result of analysis, the drainage from pumping station does not affect the river water level so much. Therefore it is the first priority to keep the capacity for the pumping by the embankment construction, instead of the new retarding basin.

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