is a concrete

gravity dam A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by using only the weight of the material and its resistance against the foundation to oppose the horizontal pressure of water pushing against it. ...

in Nantan, Kyoto Prefecture,

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

. Constructed from 1992 to 1996, the dam has a height of 67.4 m and a length of 438 m. It creates the artificial lake , with an area of 2.74 km². Initial planning for its construction started in 1961, as a measure to protect downstream area from frequent floods by the Katsura river. Hiyoshi Dam is used for three main purposes:

flood control Flood control methods are used to reduce or prevent the detrimental effects of flood waters."Flood Control", MSN Encarta, 2008 (see below: Further reading). Flood relief methods are used to reduce the effects of flood waters or high water level ...

, river maintenance and

water supply Water supply is the provision of water by public utilities, commercial organisations, community endeavors or by individuals, usually via a system of pumps and pipes. Public water supply systems are crucial to properly functioning societies. Thes ...

. The dam temporarily stores surges in river water during

flood A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrol ...

s, regulating the flow and avoiding damage to downstream areas. The dam is designed for 100-year floods (floods estimated to occur once every 100 years). The maximum release of water during flood control operations in normal situations is 150 m³ per second. However, if not enough, the dam is able to discharge more water when the level in the reservoir surpass the surcharge water level. One such situations occurred in September 2013, when heavy rain from

Typhoon 18 The Typhoon 18 is a family of American trailerable sailboats that was designed by Carl Alberg as day sailers and cruisers, first built in 1967.Sherwood, Richard M.: ''A Field Guide to Sailboats of North America, Second Edition'', pages 98-99. ...

forced a maximum outflow of 504 m³ per second. In case of emergency, with floods bigger than the estimated 100-year flood for which the dam is designed, the emergency

spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...

s can discharge up to 3,100 m³ per second, ensuring the safety of the structure. These spillways have been used only during trials. The dam also helps to ensure that the river water flow downstream is above a certain minimum level during drought periods. Hiyoshi Dam also supplies 3.7 m³ per second of additional water supply, sufficient for about 1 million people, supplying domestic water to cities in Kyoto Prefecture,

Osaka Prefecture is a Prefectures of Japan, prefecture of Japan located in the Kansai region of Honshu. Osaka Prefecture has a population of 8,778,035 () and has a geographic area of . Osaka Prefecture borders Hyōgo Prefecture to the northwest, Kyoto Prefecture ...

and Hyogo Prefecture. Hiyoshi Dam includes a small hydroelectric power generator with a capacity of 850 kW. The energy is used to power the dam facilities, with the excess generation sold to the grid. 188 houses were submerged.

Gallery

File:Hiyoshi-1407-r1.jpg, Emergency spillways File:Hiyoshi dam.jpg, The park downstream of the dam File:Hiyoshi Dam top 1.jpg, On the top of the dam File:日吉ダム.jpg, Hiyoshi Dam visitor center

References

{{Dams in Kyoto Prefecture Dams in Kyoto Prefecture Dams completed in 1996 1996 establishments in Japan

Gallery

See also

References