frequently following typhoons. As an attempt to solve the problem, in 1689 the Tenjin-gawa channel connected lakes Shinji and Nakaumi, and in 1787 the Sada-gawa channel was constructed and linked lake Shinji directly to the sea. However, their outflow was not enough for flood control. In 1832 Hii was linked to lake Shinji by the Shin River, which was constructed to the south of its former course, but accumulation of sediment led to its closure in 1939. In the 20th and 21st centuries devastating floods occurred in years 1943, 1945, 1972, 2003 and 2006. In 2003 the flood caused the death of 3, 1460 homes were flooded. The catastrophic 1972 flood resulted in death of 12 and damaged 24953 homes. Over 70 km2 was flooded and the area remained submerged for over a week. In the 1990s works commenced on a vast flood control system, including the construction of a discharge channel connecting Hii and Kando rivers. It diverts the excess water through Kando river into the Taisha Bay Since then the Kando river is regarded as a part of Hii river system. The channel, completed in 2013, received the 2014 Outstanding Civil Engineering Achievement Award. Additional elements of the flood control system are the Obara dam on Hii river and the Shitsumi dam on Kando river, as well as renovation of the Ohashi river. Economics In the Middle Ages the river comprised an important transport corridor, through which rice and iron were shipped downstream. Typically the goods were shipped using the takasebune boats up to Shoubara (on lake Shinji), where they could be loaded on larger sailing ships. An additional route was created in the late 17th century with the construction of a canal between Kurihara and Taisha Bay. It that case the goods were shipped to Uryu port at the west end of Shimane peninsula. 70% of rice paddies in Hii catchment are irrigated used its water. Most of the paddies are located in the east of Izumo plain. The river is used to supply drinking water to Matsue and Izumo cities. The Obara and Hinobori dams are located on the river. They are the main obstacles for fish migration on Hii. The Obara dam impounds the 60 million m3 large Sakura-Orochi lake that is used for drinking water supply, irrigation, flood control and recreation. In total there 14 hydropower plants on the Hii river, which together generate