A university professor said Monday that restoring tideland at Isahaya Bay in Nagasaki Prefecture by letting seawater back in will make the controversial and now scaled-back land reclamation project far more cost-effective.
Koichi Miyairi of Aichi University estimated that if the national government restores the tideland, which functions as a water purifier, by permanently letting in seawater through the floodgates of a dike traversing the bay, the investment efficiency ratio of the project would exceed 1.0.
The government reclamation project was originally intended to create 1,400 hectares of farmland by filling in the 3,550-hectare reservoir created in the bay by the dike, but the planned area was slashed by half in December after local fishermen said the project is the cause of poor seaweed harvests.
Consequently, the investment efficiency ratio for the revised project fell to 0.83 from 1.01, Miyairi said. He also said it would result in 40 billion yen in overinvestment.