Kamigaura Bay

Kamigaura belongs to the upper inlet of Kasumigaura in Hitachi, in the lowland water system around Tsuchiura. Archaeological reporting identifies the inlet in relation to the Sakuragawa river plain. Its early modern setting was a changing lake and channel landscape, whose connections with the sea were altered by works far beyond a single shore settlement.

The Tokugawa diversion of the Tone River, completed in 1654, opened a water route linking Kasumigaura with Edo. It also increased the sediment reaching the lake's southeastern approaches. By the middle of the seventeenth century the connection with seawater was weakening and the waters were becoming fresher. Cargo from northeastern Japan could pass through this inland route towards Edo. The passage reduced exposure to dangerous seas, but required transshipment, and traffic gradually favoured other routes around the Boso Peninsula. Kamigaura's history therefore belongs to a regional system in which river engineering changed both navigation and the character of the water itself.