Jōtō

Jōtō lay east of the Asahi River in Bizen, across the water from the castle town of Okayama. Its low fields repeatedly suffered when the river's left bank failed. Protecting the castle town could also increase the burden on the district: a flood-diversion scheme directed excess water southeastward across Jōtō's farmland.

The destructive flood of 1654 prompted proposals associated with Kumazawa Banzan. Tsuda Nagatada advanced the plan in 1669, and an overflow embankment was constructed in 1670. Its relief of Okayama came at a heavy cost to the fields receiving the water. Later works sought to combine flood control with land reclamation. In 1686–1687 the Hyakken River channel was developed further, and in 1692 it was carried through to Kojima Bay alongside the Okinitta reclamation. A detention basin and sluices at the mouth helped discharge water and prevent the tide from flowing back. Jōtō's fields thus became central to the domain's hydraulic engineering.