Next week, the most entertaining show in town, the deliberations of the Government Revitalization Unit, which holds hearings on government programs with the aim of cutting budegetary waste, will start again. According to various news reports, one of the main targets of the council this time will be the long-term public works project to improve flood control effectiveness in Tokyo and Osaka. Though Japanese rivers that pass through urban and suburban areas usually have extensive levee systems, some of which are centuries old, these embankments are thought to be no guarantee against the inundation of bordering communities in the event of a major storm. In 1986, a levee in Ibaraki Prefecture collapsed causing damage to surrounding neighborhoods, thus prompting the Liberal Democratic Party government at the time to initiate an ambitious public works project to shore up all the levees in the Tokyo and Osaka metropolitan areas, where many residences are actually situated below sea level. In the Kanto region, this project is being carried out for the Tone, Edo, Arakawa and Tama Rivers; while in Kansai construction is taking place on the Yodo and Yamate Rivers. Altogether, 872.4 km of waterways are targeted.
The method of reinforcement is to build “super teibo.” Teibo is the Japanese word for “levee” or “embankment.” Existing levees are essentially elevated banks that separate residences from the river. A super teibo would extend the elevation into the residential area, effectively raising the level of the area higher than the level of the river. In the event of a flood that rose above the level of the levee, not only would the levee hold, but the amount of water inundating inhabited areas would be greatly reduced.