In this study, we focused on the river natural regeneration in the subtropical island region with poor water resources, and evaluated the priority of nature restoration considering water shortage risk management. Eight rivers were decided with high priority for natural regeneration from the viewpoint of the habitat potential of Ryukyu Ayu, in the rivers of Okinawa island. In these rivers, where the river crossing structures such as dams and water intake weirs are considered to be inhibitory factors for Ryukyu Ayu habitat, we examined the possibility of removing weirs from the viewpoint of stable water use. As a result, it was shown that stable water supply is possible even in the scenario where the number of tourists is increased, indicating that the withdrawal of the intake weir is sufficiently possible.

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