|Budget Amount *help
¥1,400,000 (Direct Cost : ¥1,400,000)
Fiscal Year 1992 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1991 : ¥700,000 (Direct Cost : ¥700,000)
Every high dam for water resources development in Japan has its own written operation rules, which conform to the standard operation rules prepared by the Ministry of Construction. However, these standard rules aren't perfect for dam operators who are requested to bring the highest security to both flood operation and water supply. This report focuses on the advance release to prepare the storage room in the reservoirs that serve irrigation.
Most of operators don't rely on the standard operation: releasing stored water just after the issue of storm warning. They instead limit the actual full water level far below the designed full water level, especially during the dangerous season of high flood. This operation result in the loss of water (5 to 10% of available capacity) which farmers complain of.
A case study of Habu Dam in Yahagi River, central Japan, is performed to develop a new operation procedure that gives high security to flood management and less damage to water supply Habu Dam, constructed in 1968, has the catchment area of 51 km^2 and its reservoir has the available storage capacity of 18.5 million m^3. The maximum high-water flow is 546.4 m^3/s. Through the analysis of the rainfall forecasts issued from the meteorological observatory and the record of water level in the reservoir, the criterion to perform advance release should be "80 mm or more" in the forecast. This would lead to the performance of 1.3 times a year in average. To lower the full water level by 10 cm (equivalent to 100,000 m^3) is preferable to meet sudden small floods and to increase the flood management security.