Twelve municipalities hit hard by the tsunami after the Great East Japan Earthquake plan to elevate the ground level in once-submerged urban areas–one by up to 17 meters–to aid in the rebuilding of towns and cities in their prior locations, The Yomiuri Shimbun has learned.
The targeted areas together measure 740 hectares, nearly 15 times larger than Tokyo Disneyland, and the quantity of dirt required is calculated to be 17.5 million cubic meters–enough to fill the Tokyo Dome 14 times. Some municipalities are concerned about the delay in beginning work due to a shortage of dirt and other logistical factors.
The Yomiuri Shimbun surveyed 37 municipalities in coastal areas in Iwate, Miyagi and Fukushima prefectures. Twelve of them, including Miyako, Iwate Prefecture, and Iwaki, Fukushima Prefecture, plan to conduct land readjustment to rebuild their urban areas in 26 districts.
As of Friday, none of these districts had started work, and only six have officially determined the districts in which work is to proceed based on the City Planning Law.
While most of them plan to raise the ground level by one to six meters, the municipal government of Onagawa, Miyagi Prefecture, aims to raise it by up to 17 meters, which would make the area 18 meters above sea level. The mound will be as high as a five-story condominium.
So far, 11 municipalities have released cost estimates for the planned land elevation and readjustment, together totaling about 300 billion yen. If approved, the central government would pay for all of it. The work in 12 districts in eight municipalities is expected to be completed in fiscal 2017 or later. The project in the district around JR Ofunato Station in Ofunato, Iwate Prefecture, is slated to be finished in fiscal 2020.
The municipalities’ plan is to secure the necessary dirt by cutting away part of nearby hills or using dirt generated by projects to transfer groups of residents to higher ground. But districts in at least five municipalities are likely to have difficulty securing enough dirt because there are no such hills nearby, or because a large quantity of dirt is needed for other projects including dike construction. Though some are considering procuring dirt from the Tokyo metropolitan area, the transport cost could be immense.
Another concern is soft ground in some areas, which might cause land to sink after the mound work. Kesennuma, Miyagi Prefecture, and other municipalities therefore insist on the need for ground improvement. “The necessity for conducting land improvement will largely affect the cost and schedule of the work,” said an expert.
The municipalities plan to widen roads and build parks that could be used as evacuation centers in a disaster in the newly heightened areas. Because the plans involve sections of private land, municipalities will need to reach a consensus with local residents on the issue.