Abstract
Fukuoka Metropolitan Area, a fast growing economic and cultural center in Kyushu, was struck by severe droughts in 1978 and 1994. This area has a geographical disadvantage to supply sufficient water. Although there are many rivers in the area, they are all small with insufficient and unstable discharge due to the small catchment areas. The water taken from the Chikugo River, which is located outside of the area, supplies about one third of the total water demand through the Fukuoka District Waterworks Agency.
The 3rd severest drought struck the Chikugo River basin in 2002. However, water supply for the Fukuoka Metropolitan Area was not seriously affected by the drought.
In this study, the reservoir operations by the authorities during the drought were investigated. Besides, the variation of the water storage of Egawa and Terauchi reservoirs in the Chikugo River basin without Yamaguchi Reservoir was simulated. The amount of water deficit was calculated through the simulations, and the effect of the reservoir on the drought was evaluated. It was found out that the Yamaguchi Reservoir played a significant role for drought operation. If it had not been for the Yamaguchi Reservoir, the stored water that this agency owned at Egawa and Terauchi reservoirs would have been vacant. As a result, the Yamaguchi Reservoir has a great effect on avoiding water rationing in Fukuoka Metropolitan Area.
