The is a river on the island of Kyushu, flowing through the Saga Prefecture.
The river rises on the slopes of Mount Jinroku (ç¥Âå Âå±±, ), located in the Takeo city. In the mountains it joins Takeo River, then flows through the Shiroishi plain. After the confluence with Ushizu River it discharges into Ariake Sea, a part of East China Sea.
The Rokkaku river is long and the catchment area is ; the population of the catchment is about 120,000. It is designated as a Class A river by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT).
About 37% of the catchment is covered by natural vegetation, about 50% agricultural lands, and about 13% is built up.
The bottom gradient is about 1/60 in the upper reaches, 1/1501/1000 in the middle, and 1/15001/45000 in the lower part.
In the 20th century devastating floods occurred in years 1953, 1967, and 1990. The 1953 flood caused the death of 3 and submersion of 14,000 homes.