For the water management of the Yabe River, which runs in the southern part of Fukuoka Prefecture, Japan, characteristic condition of river dynamics and histories of flood control were surveyed from historical materials. Length of main stream is 58.3km and catchment area is 618km^2. The area of paddy irrigated in the basin is about 15,OOOha. The Yabe River is disadvantageous for use of water resources because of large coefficient of river regime, which denotes the stability of a flow. Alluvial fan, where a river runs irregularly, has spread in middle and lower basin. River course might change irregularly in ancient times. The form of river has been fixed to be suitable for human lives since agricultural fields were reclaimed and villages were developed in the alluvial fan. Two forks in the right bank of the river were dug or repaired to keep water for irrigation about 1200 years ago. Constructing of levees and working for bank protection fixed the shape of the river during the conflict between two clans, which lied on opposite bank, from 1621. The course of river has changed little although there have been floods occasionally since the Edo era. Floods have caused damage to the middle basin because of irregular flow that is characteristic in an alluvial fan. Repair such as changing of rapid and planting trees has been partially until the Meiji era, and modern construction with a national subsidy has been conducted after the Meiji era. A dam for multi purpose constructed in the upper stream has controlled flood.
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